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Stimuli‐responsive, optically‐active colloidal systems are convenient signal transducers capable of monitoring environmental changes at the nanoscale. We report on the coupling of chemo‐thermal cycloaddition reaction with temperature‐sensitive, DNA‐coated gold nanoparticles. We found that the concentration of chemical fuel, dictating the temperature of the mixture, is a primary ingredient in controlling the extent of the reversible clustering of gold nanoparticles. Our results show that rational coupling of chemical and colloidal systems can open up new possibilities in tracking the change of local temperature using aggregation/redispersion of nanoparticles. [ABSTRACT FROM AUTHOR]

It was shown that a catalyst obtained by depositing palladium nanoparticles from a colloidal solution onto a carbon support stabilized with polyvinylpyrrolidone exhibits higher activity in liquid-phase hydrogenation of o-nitrotoluene than a commercial sample of Pd/C with the same palladium content. From analysis of data from TEM, XRD, and XPS it was concluded that the increase of activity is due to the increased content of Pd0 in the synthesized catalyst. [ABSTRACT FROM AUTHOR]

Highlights • Exothermic of pulverized coal on various oxygen concentrations was researched. • Revealing three oxidation stages of low-temperature oxidation of pulverized coal. • Apparent activation energies on various oxygen concentrations were investigated. • Low oxygen concentration had inhibitive effect on exothermic of pulverized coal. Abstract Low-temperature exothermic oxidation characteristics of pulverized sub-bituminous coal was investigated using differential scanning calorimetry system in atmospheres where the oxygen concentrations were 21, 17, 13, 9, and 5 vol. %, respectively. The results indicate that the heat flow gradually decreases after it reaches the maximum value. A decreased oxygen concentration had a delaying effect on the heat flow and derivative of heat flow curves. A low oxygen concentration has typical stage characteristics for inhibiting the exothermic oxidation of pulverized coal. The oxygen concentration has a significant influence on the kinetics characteristics and kinetics parameters. The apparent activation energy increased under different oxygen concentrations with an increase in the conversion rate. The apparent activation energy was less than that in the low oxygen concentration under a high oxygen concentration. When the oxygen concentration less than 9%, the activation energy increases significantly. [ABSTRACT FROM AUTHOR]

Saturated, aromatic, resin, and asphaltene (SARA) group and fractional composition of 14 samples of marine residual fuel oils and components suitable for their production is studied. Analysis of the results of laser Fourier-difractometric study of solutions of these samples in isooctane made it possible to develop a quantitative method of assessment of their colloidal stability. Correlative relationships of the composition and colloidal stability of the studied asphaltene-containing and asphaltene-free petroleum products are derived. The inapplicability of the term “straight-run” for assessment of colloidal stability of residual fuels is shown experimentally. [ABSTRACT FROM AUTHOR]

A novel nuclear reactor concept is presented in this paper which can sustain the controlled fission reaction and has an innovative mechanism of reactivity control. The concept of this reactor is based on the stability of colloidal suspensions. These suspensions consist of colloidal fuel particles suspended in a moderator with a controllable separation distance. The packing factor of the colloidal suspension can be controlled by slightly modifying the ionic concentration of the suspension medium, effectively controlling the criticality of the reactor. Based on local average separation distance between particles, thermalization of neutrons can be varied and can be used to manipulate neutron multiplication factor k ∞ . Numerical calculations are performed with the help of MCNP software to obtain optimal configuration of critical assemblies. For the numerical case studies presented in this paper, uranium dioxide ( UO 2 ) fuel particles with size ⩾10 μ m in different liquid solvents are considered. The fuel particles are simulated as hard spheres packed in Bravais lattice structures within the solvent medium. Simulations involve neutron interactions of a uniform colloidal suspension of spherical fuel elements of diameters 5 cm–0.001 cm. The homogeneous fuel equivalence was found to occur for particles sized below 0.010 cm diameter. Criticality curves are generated for fuel particle configurations with varying particle density, confirming fuel configurations can be controlled by only modifying particle packing factor. Additional criticality curves are generated for various cylindrical geometries of fuel suspension vessels with modular form factors. Triethylene glycol is substituted as a moderator and suspension fluid with higher boiling point as compared to water. The type of moderator or solvent does not have any significant impact on criticality performance. [ABSTRACT FROM AUTHOR]

Janus particles are of great research interest because of their reduced symmetry, which provides them with unique physical and chemical properties. Such particles can be prepared from spherical structures through colloidal assembly. Whilst colloidal assembly has the potential to be a low cost and scalable process, it typically lacks selectivity. As a consequence, it results in a complex mixture of particles of different architectures, which is tedious to purify. Very recently, we reported the colloidal synthesis of Au semishells, making use of polystyrene-polyphenylsiloxane Janus particles as an intermediate product (Chem. Commun. 2017, 53, 3898-3901). Here, we demonstrate that these Janus particles are realized through colloidal assembly of spherical glucose-functionalized polystyrene particles and an emulsion of phenyltrimethoxysilane in aqueous ammonia, followed by interfacial polycondensation to form the polyphenylsiloxane patch. Both the polystyrene spheres and the emulsion of Ph-TMS in aqueous ammonia are stabilized by a surfmer-a reactive surfactant. The colloidal assembly reported in this manuscript proceeds with an unexpected high selectivity, which makes this process exceptionally interesting for the synthesis of Janus particles. Furthermore, we report insights into the details of the mechanism of formation of these Janus particles, and apply those to adapt the synthesis conditions to produce polystyrene particles selectively decorated with multiple polyphenylsiloxane patches, e.g., raspberry particles. [ABSTRACT FROM AUTHOR]

Calcium phosphate buildup is important for biological processes (e.g., bones and teeth growth) and negatively affects the efficiency and functioning of water systems (e.g., cooling water systems and boilers) as a result of scale buildup by salts precipitation. Thus, stable aqueous dispersions of calcium phosphate particles can effectively prevent the formation and buildup of scale in water systems. In this study, the stabilization of calcium phosphate nanocrystals (NCs) was studied by forming a supersaturated solution in the presence of poly acrylic acid/2-acrylamide-2-methylpropane sulfonic acid p(AA/AMPS) containing carboxy and sulfo group functionalities. Calcium phosphate NCs were formed and subsequently aggregated in a supersaturated aqueous solution containing 2-phosphonobutane-1,2,4-tricarboxylic acid without any copolymers. Aggregation of calcium phosphate NCs was suppressed in the presence of polymeric molecules containing carboxy groups, whereas molecules bearing sulfo groups were ineffective in dispersing calcium phosphate NCs. However, copolymers bearing both functional groups enhanced the dispersibility of calcium phosphate NCs. Using a combination of light scattering and surface charge measurements along with electron imaging, we found that the inhibition of calcium phosphate precipitation originates from hydroxyapatite nanocrystals (HANCs) with a size smaller than 100 nm in solution. While the carboxy groups in the copolymer adsorbed on the surface of the HANCs, the sulfo groups provided these species with an overall negative surface charge, thereby increasing their colloidal stability via electrostatic repulsion. These results indicated that the aggregation of the HANCs can be effectively hindered using sulfo/carboxy bifunctional copolymers. [ABSTRACT FROM AUTHOR]

A method using multi-fluid Eulerian computational fluid dynamics (CFD) model to study the migration of pulverized coal in coal-bed methane (CBM) wellbore is presented in this paper. The study aims to predict the condition of discharging pulverized coal out of CBM wellbore and decrease downhole failures such as low efficiency, pump leakage and stuck pump caused by the deposition of pulverized coal. On basis of production conditions of CBM wells in Ordos Basin of China, the transient model of pulverized coal-liquid two-phase flow in the annulus between sucker rod and tubing is established by CFD software, and the effects of pulverized coal size and well liquid inflow velocity on the output of pulverized coal are investigated. On the process of simulation, the distribution and volume fraction changes over time of pulverized coal in the annulus are analyzed, the critical drainage volume of CBM well for discharging pulverized coal is determined, and the output of pulverized coal in every case is predicted. Based on simulation results, the recycle water supplement technology to cleanout pulverized coal in the wellbore is put forward and tested in CBM field. The satisfactory performances of tests show the validity of the CFD study results and the practicability of the recycle water supplement technology. [ABSTRACT FROM AUTHOR]

The synthesis and spontaneous, reversible supracolloidal hydrogen bond-driven self-assembly of cobalt nanoparticles (CoNPs) into hollow shell-like capsids and their directed assembly to higher order superstructures is presented. CoNPs and capsids form in one step upon mixing dicobalt octacarbonyl (Co2CO8) and p-aminobenzoic acid ( pABA) in 1,2-dichlorobenzene using heating-up synthesis without additional catalysts or stabilizers. This leads to pABA capped CoNPs (core ca. 5 nm) with a narrow size distribution. They spontaneously assemble into tunable spherical capsids ( d≈50-200 nm) with a few-layered shells, as driven by inter-nanoparticle hydrogen bonds thus warranting supracolloidal self-assembly. The capsids can be reversibly disassembled and reassembled by controlling the hydrogen bonds upon heating or solvent exchanges. The superparamagnetic nature of CoNPs allows magnetic-field-directed self-assembly of capsids to capsid chains due to an interplay of induced dipoles and inter-capsid hydrogen bonds. Finally, self-assembly on air-water interface furnishes lightweight colloidal framework films. [ABSTRACT FROM AUTHOR]

The impact of feed ionic concentration in the presence of organic and colloidal foulant on osmotically driven membrane processes (ODMPs) was demonstrated. The normalized flux of ODMPs was significantly decresed in both DI and 10 mM NaCl feed solution when the feed solution contained colloidal particles as foulants due to the deposition of colloidal particles on the membrane surface. The deposited colloidal particles strongly promoted cake-enhanced osmotic pressure near the surface of the membrane. In contrast, the normalized flux of ODMPs was slightly increased when humic acids (HA) were added as the organic foulant into the feed solution. The attachment of HA molecules changed the membrane surface conducting it more hydrophilic, and induced a stronger diffusion of water molecules into the membrane active layer. As a result, both the increased feed ionic strength and deposited colloidal fouling did not significantly alter the reversal salt selectivity of the ODMPs, while the reversal salt selectivity was significantly incresed after the addition of HA molecules to the feed solution because the HA molecules changed the properties of the membrane surface. [ABSTRACT FROM PUBLISHER]

Diffusion with transient binding occurs in a variety of biophysical processes, including movement of transmembrane proteins, T cell adhesion, and caging in colloidal fluids. We model diffusion with transient binding as a Brownian particle undergoing Markovian switching between free diffusion when unbound and diffusion in a quadratic potential centered around a binding site when bound. Assuming the binding site is the last position of the particle in the unbound state and Gaussian observational error obscures the true position of the particle, we use particle filtering to predict when the particle is bound and to locate the binding sites. Maximum likelihood estimators of diffusion coefficients, state transition probabilities, and the spring constant in the bound state are computed with a stochastic Expectation–Maximization (EM) algorithm. [ABSTRACT FROM AUTHOR]

This paper analyses the applicability of well-known risk management methodologies in energy efficiency projects in the industry. The possibilities of application of the selected risk management methodology are demonstrated within the project of the plants for injecting pulverized coal into blast furnaces no. one and two, implemented by the company US Steel Serbia d.o.o. in Smederevo. The aim of the project was to increase energy efficiency through the reduction of the quantity of coke, whose production requires large amounts of energy, reduction of harmful exhaust emission, and increase productivity of blast furnaces through the reduction of production costs. The project was complex and had high costs, so that it was necessary to predict risk events and plan responses to identified risks at an early stage of implementation, in the course of the project design, in order to minimise losses and implement the project in accordance with the defined time and cost limitations. [ABSTRACT FROM AUTHOR]

Fan/impact mills are commonly applied in the grinding and dilute–pneumatic transportation of lignite or brown coals with high moisture contents to the furnaces in large steam boilers. Each of the two to eight mills feeds pulverized coal into two or more burner nozzles. An online detection of the pulverized-coal mass flow distribution among the burners is vital for the control of the combustion process. Knowing the distribution, measures for the redistribution of the coal or, alternatively, for the adjustment of the combustion air flow according to the actual distribution can be employed. Determining the characteristics of a gas–solid two-phase flow using an electrostatic principle is a promising online method of measurement because it is robust and inexpensive. Furthermore, due to their better spatial sensitivity, rod sensors are more suitable for large rectangular ducts related to fan/impact mills than ring-, pin-, or arc-shaped sensors. Sets of 1-D and 2-D electrostatic sensor arrays with a corresponding data acquisition system were employed to determine the mass flow distribution in the cross section of the duct that feeds the pulverized lignite to the four burner nozzles. Various operating regimes for the fan/impact mill were tested. The time series of the signals from the electrostatic sensors were analyzed statistically. It was shown that the skewness, kurtosis, and autocorrelation time delay at the characteristic value can indicate different grinding qualities of the coal. [ABSTRACT FROM PUBLISHER]

Abstract: In the presented work we investigate the influence of the Pt to carbon ratio on the degradation behavior of Pt based proton exchange membrane fuel cell (PEMFC) catalysts. In order to enable a systematic investigation, we utilized a recently developed colloidal synthesis approach for preparing catalysts with identical Pt nanoparticles (NPs), but varying Pt loadings. Two different commercially available, standard carbon supports were used, Vulcan XC72 and Ketjenblack EC-300. We evaluated the influence of the platinum loading on the electrochemical surface area (ECSA) loss by applying accelerated stress tests simulating a load-cycle in a PEMFC and start-up/shutdown conditions. Simulating load cycles, no clear influence of the Pt loading on the ECSA loss is observed, whereas the ECSA loss significantly increases with increasing Pt loading when simulating start-up/shutdown conditions. [Copyright &y& Elsevier]

Highlights: [•] Optimized performance of an MBR depends on biomass viability and membrane fouling. [•] Accumulation of SMP and colloidal compounds within MBR may affect biomass viability. [•] Proposed conceptual models correlate biomass viability with membrane fouling. [•] Easily measurable parameters are introduced in the models to represent SMP. [ABSTRACT FROM AUTHOR]

Pulverized coal is one of the main controlling factors restraining the production capacity of coal-bed methane wells during CBM extraction. In order to identify the sources of pulverized coal particles and reveal the mechanism of pulverized coal generation, with Hancheng coal field as an experimental area, using light transmission microscopy, laser particle size testing, X-ray diffraction, and reflection polarized optical microscopy, the characteristics of pulverized coal collected during CBM extraction were analyzed for its concentration, particle size, and composition. Combining with the coal seam characteristics, authors finds that the main controlling factors of pulverized coal generation include well type, well completion technology, extraction system, coal petrography characteristics, coal body structure and coal seam structure. In particularly, the coal body structure is the principal control factors of pulverized coal generation. [ABSTRACT FROM AUTHOR]

Abstract: Pulverized coal combustion in mixture of oxygen and recycled flue gasses, known as oxy-fuel combustion, is considered as one of the several possible alternatives to conventional pulverized coal combustion. Switching from conventional pulverized-coal combustion to oxy-fuel combustion brings significant changes in flame properties among which the most important are ignition properties and flame stability. This paper presents the results of experimental and numerical analysis of ignition phenomena under O2/CO2 mixtures with different oxygen content. The main focus of the presented paper is to suggest novel ignition sub-model which can describe all possible ignition mechanisms. Proposed ignition sub-model together with Large Eddy Simulation (LES) turbulence modeling enables accurate prediction of main flame characteristics: ignition point position, ignition temperature, and flame stability. [Copyright &y& Elsevier]

The study of heavy organics such as asphaltene and their thermodynamic behavior is of great importance while occurrence of their precipitation and deposition in production and processing. In this work, the asphaltene precipitation of a sample oil is investigated through simulation and the results are compared with experimental data. The results revealed that each grouping (splitting–lumping) indicates a discrete outcome. Some results had a great deviation compared to the experimental data and some were in good agreement. [ABSTRACT FROM AUTHOR]

Abstract: The energy distribution coefficient (X c), the fraction of the total heat of reaction released at the char surface during combustion of char particles, was studied using the improved moving flame front (MFF) model. The energy distribution coefficient (X c), considering homogeneous oxidation of CO in the boundary layer of the particle and reduction of CO2 at the surface, was derived explicitly. Under conditions in practical pulverized coal flames, the energy distribution coefficient (X c) and the effective energy distribution coefficient (X e), based on the heat-release calculated using the traditional single film model with CO as the only reaction product (SF-CO), were calculated and compared with the value commonly used in the SF-CO model. The results obtained show that the smaller the particle diameter, the greater the energy distribution coefficient. For the same particle diameter, the higher the particle temperature, the lower the energy distribution coefficient. Under the conditions of the calculation, the average value of the energy distribution coefficient X c is approximately 0.7, and the average value of the effective SF-CO energy distribution coefficient is greater than 0.5, significantly larger than the value of 0.3 obtained by the traditional single film model. [Copyright &y& Elsevier]

Polycyclic aromatic hydrocarbons (PAH) are known to be specific inducers of CYP1A1 expression in vertebrates. CYP1A1 induction has been widely studied in mammal cell cultures or in vivo, in conditions of exposure to single PAH chemicals. Here, we studied the possible transfer of PAH to rats via the food chain in environmentally-relevant conditions. Rats were fed for 2 days with PAH-contaminated mussels sampled on coasts polluted by the Erika oil-tanker wreck. CYP1A1 expression was investigated by measuring mRNA levels and EROD enzymatic activity over the 84 h following the last ingestion. CYP1A1 expression in treated rats was compared to controls fed with mussels free from PAH contamination. The results showed that ingestion of PAH-contaminated mussels induced CYP1A1 mRNA and EROD activity. Increase of transcriptional level and of EROD activity was transient with a peak within 12 h and a return to basal levels within 36 h. [ABSTRACT FROM AUTHOR]

The performance properties of the initial components and finished product were evaluated during fabrication of models of commercial lube oils by scattered light correlation spectroscopy. This method allows determining the size and average radius of colloidal formations and the stability of colloidal solutions against separation. Using the data obtained, changes can be made in the manufacturing technology and formula of the oils by changing the mixing temperature and parameters of the initial components: the indexes of the base, the sequence of incorporating the additives, and the concentration and composition of the additives. [ABSTRACT FROM AUTHOR]

The basic physicochemical characteristics of fabrication of three-phase colloidal fuels were analyzed. The effect of the nature and content of solid and liquid phases, type of chemical additives (plasticizers, emulsifiers, and stabilizers), and the basic methods of obtaining three-phase systems from bituminous coals and brown coals were examined. [ABSTRACT FROM AUTHOR]

In the present paper the potential application of colloidal gas aphrons (CGA) to the recovery of antioxidants from wine-making waste extracts is investigated. CGA were generated by stirring a buffered solution (400 ml) of a cationic surfactant(cetyltrimethylammonium bromide, CTAB) at 8000 rpm for 10 minutes. Trials were carried out on standard solutions (2 ml) of gallic acid (GA) 200 mg/l with varying volumes of colloidal gas aphrons (20-60 ml) generated with varying concentrations of CTAB (2 and 4 mM). Influence of pH, solvent (buffered aqueous solution and ethanol), CTAB to GA molar ratio on recovery were studied. Best recovery (63%) was achieved from an aqueous solution of GA and at a CTAB to GA molar ratio of 16. Separation is mainly driven by electrostatic interactions but pH conditions are to be optimised to preserve the GA antioxidant power. [ABSTRACT FROM AUTHOR]

Optimization of cracking process parameters, which determine the efficiency of the reaction volume, is the most important problem in creating industrial stages of thermal destruction of “native” petroleum residues – atmospheric and vacuum resids. A simplified approach to design of the reaction apparatus for refining such residues will result in large differences in these parameters during use and is due to insufficient information on the colloidal state of the feedstock mixture, kinetic characteristics of its conversion, and hydrodynamics of the material streams in the reaction volume. [ABSTRACT FROM AUTHOR]

The rheological properties of crude oils from Yuzhno-Inzyreisk and Vostochno-Khar’yaginsk fields in Arkhangel’sk Oblast were investigated at different temperatures and shear rates. The anomalies of these properties are due to the high concentration of waxes capable of phase transitions in the crudes. The activation energy of viscous flow, which increased with the wax content in the crudes, was determined with the dependence of the logarithm of the viscosity on the reciprocal of the temperature. Treatment with a high-frequency electromagnetic field significantly decreases the viscosity of the crudes. [ABSTRACT FROM AUTHOR]

Experimental studies showed that colloidal subsystems of resins and asphaltenes in metastable state are most probably the basic carriers of the “thermal memory” effect of petroleum fluids. The structural transformations of the colloidal system of asphaltenes revealed probably are universal in character and are characteristic of petroleum residues of different geographic origin. It was found that not only thermodynamic but also kinetic control should be conducted in processes of transformation of the disperse phase of petroleum residues. [ABSTRACT FROM AUTHOR]

The handling and properties of heavy oils are becoming an increasingly important problem. Even though petroleum is the widest used source of fuels and it has been studied for decades, its complex nature is still an enigma in several ways. A reasonable approach to a definition of a crude oil is a colloidal fluid formed by several dispersed phases from gases (light hydrocarbons) to solids (heavy paraffins and asphaltenes). Through all these years of research, applications have been found for almost all classes of components in crude oil except for some of the solid phases such as asphaltenes. Very heavy petroleum is a non-newtonian liquid with a viscosity of ≈106 Poise, and an average molecular weight of 600 amu. The solids that are toluene soluble but heptane insoluble are called asphaltenes and are the most aromatic fraction with the highest molecular weight of unconverted petroleum. In the present work, we applied high resolution transmission electron microscopy (HREM) and energy dispersive spectrometry (EDS) in the study of asphaltenes. It was found that when the asphaltenes are well separated from the resins the sample consists of a carbon structure containing S, V, Si, related to fullerenic carbon. During observation in the microscope it was possible to see the formation of fullerenes such as onions and C240 @ C60 structures. The fact that they decomposed under further irradiation suggests that they are metastable structures. Since the heteroatoms are still present they are likely to cause instability to the structure. Not only does our result indicate the possibility of obtaining fullerenes from crude oil but it also suggests the asphaltene molecule, when it is resin free, might be a precursor of fullerenic structures. [Copyright &y& Elsevier]

Examines the heterocoagulation behavior of oxide-mixture/ethanol suspension systems. Dispersions consisting of large, monodispersed, spherical silica and small alumina of particles; Achievement of the design of heterocoagulates of controlled architecture; Control of the colloidal stability of the constituent particles.

For fluctuating currents in nonequilibrium steady states, the recently discovered thermodynamic uncertainty relation expresses a fundamental relation between their variance and the overall entropic cost associated with the driving. We show that this relation holds not only for the long-time limit of fluctuations, as described by large deviation theory, but also for fluctuations on arbitrary finite time scales. This generalization facilitates applying the thermodynamic uncertainty relation to single molecule experiments, for which infinite time scales are not accessible. Importantly, often this finite-time variant of the relation allows inferring a bound on the entropy production that is even stronger than the one obtained from the long-time limit. We illustrate the relation for the fluctuating work that is performed by a stochastically switching laser tweezer on a trapped colloidal particle. [ABSTRACT FROM AUTHOR]

Review: 293 refs. [ABSTRACT FROM AUTHOR]

We present in detail the fluorescence properties of single thick-shell CdSe/CdS colloidal nanocrystals coupled to a linear one-dimensional gold grating. In addition to the photoluminescence decay rate increase, we point out that the polarization ratio of the emission is dramatically enhanced. It overcomes 80% and can reach values close to unity. Experimental results are successfully compared to theoretical predictions. Blinking suppression is also reported. [ABSTRACT FROM AUTHOR]

Passive site stabilization is a new technology proposed for nondisruptive mitigation of liquefaction risk at developed sites susceptible to liquefaction. This technology is based on the concept of slow injection of stabilizing materials at the edge of a site and delivery of the stabilizer to the target location by using the natural or augmented groundwater flow. In this research, a box model was used to investigate the ability to uniformly deliver colloidal silica stabilizer to loose sands using low-head injection and extraction wells. Five injection wells and two extraction wells were used to deliver stabilizer in a generally uniform pattern to the loose sand formation. Numerical modeling was used to identify the key parameters affecting stabilizer migration and to determine their effective values for the box experiment. In our modeling approach, the stabilizer is treated as a miscible fluid, the viscosity of which is a function of time and the concentration of stabilizer in the pore water. Inverse modeling techniques are employed to reproduce data from the laboratory experiment for the determination of soil and stabilizer properties. While the details of the stabilizer distribution were difficult to reproduce with the simplified conceptual model we used, the overall system behavior was well captured, providing confidence that numerical simulation is a useful tool for designing centrifuge model tests, pilot tests, and eventually field stabilizer-injection projects. [ABSTRACT FROM AUTHOR]