Deposition of Polymer Particles with Fibrinogen Corona at Abiotic Surfaces under Flow Conditions

The deposition kinetics of polymer particles with fibrinogen molecule coronas at bare and poly-L-lysine (PLL) modified mica was studied using the microfluid impinging-jet cell. Basic physicochemical characteristics of fibrinogen and the particles were acquired using dynamic light scattering and the electrophoretic mobility methods, whereas the zeta potential of the substrates was determined using streaming potential measurements. Subsequently, an efficient method for the preparation of the particles with coronas, characterized by a controlled fibrinogen coverage, was developed. This enabled us to carry out measurements, which confirmed that the deposition kinetics of the particles at mica vanished at pH above 5. In contrast, the particle deposition of PLL modified mica was at maximum for pH above 5. It was shown that the deposition kinetics could be adequately analyzed in terms of the mean-field approach, analogously to the ordinary colloid particle behavior. This contrasts the fibrinogen molecule behavior, which efficiently adsorbs at negatively charged substrates for the entire range pHs up to 9.7. These results have practical significance for conducting label-free immunoassays governed by the specific antigen/antibody interactions.

Formation of the Kaolin Structure Treated by Pressure

To form the technological properties of clays, various methods of their activation have been developed, the essence of which is that when processing clays, their structure (defectiveness) changes, which forms the energy potential of clay particles, and the latter is realized in the form of "specified" physicochemical properties of clays. In this regard, the effect of stress pressure on the change in the defectiveness of structural elements of kaolin was studied. Experimental studies showed that the pressure value P = 150 MPa was the boundary value at which different conditions for the formation of defectiveness of structural elements of kaolin were observed. High pressure has a multidirectional effect on the defectiveness formation of the kaolin structural elements: a package, a mineral, a colloid and an aggregate. In a package of kaolinite mineral, the defectiveness increases with increasing pressure. Defects are formed due to the removal of Al, Fe, Mg, Si ions from the octahedral and tetrahedral sheets. Al ions are the most sensitive to pressure. The removal of ions entails deformation of the packet and the formation of "hole" energy centers. Pressure up to 0–150 MPa has a greater effect on the formation of defectiveness (calculated correlation coefficient rс = 0.86) than in the range 150–800 MPa (rс = 0.82). In the kaolinite mineral at pressures up to 150 MPa, a decrease in defectiveness is observed due to the ordering of the structure under pressure (rс = 0.67). At pressures above 150 MPa, an increase in the defectiveness of the kaolinite mineral (rс = –0.72) is observed due to the destruction of hydrogen bonds between the packets, which entails the sliding and rotation of the structural packets among themselves. In a colloid (particle), with an increase in pressure to 150 MPa, the structural defect decreases due to an increase in the colloid density (rс = 0.67). In the pressure range of 150–800 MPa, it is rather difficult to reveal the effect of pressure on the formation of defectiveness (rс = 0.37). In the aggregate, with an increase in pressure to 150 MPa, the defectiveness of the structure increases due to crushing of particles, sliding and displacement of particles among themselves (rс = 0.95). In the pressure range of 150–800 MPa, it is rather difficult to reveal the influence of pressure on the formation of defectiveness (rс = 0.58), although the tendency increases with increasing pressure, the defectiveness of the aggregate remains.

Model For Mixing Process Improvement at Water Treatment Plant by Integrating Lean Manufacturing and Parameter Design

The aim of integrating lean manufacturing and parameter design is to minimize seven non-value wastes in addition to the traditional waste in clean water production. These additional wastes to be considered are overproduction, waiting, motion, transportation, inventory, overprocessing, and defects. Information obtained from each waste is the input for the parameter design of the mixing process. The result of interaction between these seven types of waste in the lean production of clean water reveals that overprocessing waste is the most influential input in the parameter design of the Taguchi method. In the process of adding the level of concentration of poly aluminium chloride coagulant in the mixing process, a turbidity level below 5 nephelometric turbidity units is obtained, which in fact is in accordance with the health standard for clean water. An observation was also made on the behavior of flocs as the effect of Brownian motion due to the attractive force of poly aluminium chloride coagulant and colloid particle. The particle was then examined using a scanning electron microscope to find out the dimension of grain-sized flocs as the result of sedimentation in the mixing process. By properly integrating lean manufacturing and parameter design to minimize waste, a quality water meeting the set standard would be produced.

Formation of the Kaolin Structure Treated by Pressure

To form the technological properties of clays, various methods of their activation have been developed, the essence of which is that when processing clays, their structure (defectiveness) changes, which forms the energy potential of clay particles, and the latter is realized in the form of "specified" physicochemical properties of clays. In this regard, the effect of stress pressure on the change in the defectiveness of structural elements of kaolin was studied. Experimental studies showed that the pressure value P = 150 MPa was the boundary value at which different conditions for the formation of defectiveness of structural elements of kaolin were observed. High pressure has a multidirectional effect on the defectiveness formation of the kaolin structural elements: a package, a mineral, a colloid and an aggregate. In a package of kaolinite mineral, the defectiveness increases with increasing pressure. Defects are formed due to the removal of Al, Fe, Mg, Si ions from the octahedral and tetrahedral sheets. Al ions are the most sensitive to pressure. The removal of ions entails deformation of the packet and the formation of "hole" energy centers. Pressure up to 0–150 MPa has a greater effect on the formation of defectiveness (calculated correlation coefficient rс = 0.86) than in the range 150–800 MPa (rс = 0.82). In the kaolinite mineral at pressures up to 150 MPa, a decrease in defectiveness is observed due to the ordering of the structure under pressure (rс = 0.67). At pressures above 150 MPa, an increase in the defectiveness of the kaolinite mineral (rс = –0.72) is observed due to the destruction of hydrogen bonds between the packets, which entails the sliding and rotation of the structural packets among themselves. In a colloid (particle), with an increase in pressure to 150 MPa, the structural defect decreases due to an increase in the colloid density (rс = 0.67). In the pressure range of 150–800 MPa, it is rather difficult to reveal the effect of pressure on the formation of defectiveness (rс = 0.37). In the aggregate, with an increase in pressure to 150 MPa, the defectiveness of the structure increases due to crushing of particles, sliding and displacement of particles among themselves (rс = 0.95). In the pressure range of 150–800 MPa, it is rather difficult to reveal the influence of pressure on the formation of defectiveness (rс = 0.58), although the tendency increases with increasing pressure, the defectiveness of the aggregate remains.

Preliminary results for natural groundwater colloids in sedimentary rocks of the Horonobe Underground Research Laboratory, Hokkaido, Japan

Colloid concentration is an important parameter in models of colloid-facilitated transport. The purpose of the present study is to characterize colloid concentrations and colloid stability in natural groundwater from the Horonobe Underground Research Laboratory (URL) in Hokkaido, Japan. The particle sizes of colloids in groundwaters from the Horonobe URL range from several nanometres to c. 500 nm, with a mode particle size of c. 120 nm. Evaluation of colloid stability by DLVO theory suggests that larger colloids (i.e. >100 nm in diameter) would be more stable than smaller colloids in some groundwaters. The estimated colloid particle concentrations when considering the results of DLVO calculations ranged from 2.33 × 106 to 1.12 × 108 particles/ml, and mass concentrations were estimated to range from 45 to 1540 µg l−1 for diameters greater than 100 nm. Colloids in Horonobe groundwaters appear to be less stable, with a moderate potential for transport, than colloids investigated in similar international studies. This reduced stability may be due to relatively higher ionic strengths and moderate dissolved organic concentrations in Horonobe groundwaters compared to their international counterparts.

On the effects from the simultaneous occurrence of the critical Casimir and dispersion forces between conical colloid particle and a thick plate immersed in nonpolar critical fluid

Here we study the interplay between the van der Waals (vdWF) and critical Casimir forces (CCF), as well as the total force (TF) between a conical colloid particle and a thick planar slab. We do that using general scaling arguments and mean-field type calculations utilizing the so-called “surface integration approach”, a generalization of the well known Derjaguin approximation. Its usage in the present research, requires knowledge on the forces between two parallel slabs, confining in between some fluctuating fluid medium characterized by its temperature T and chemical potential μ. The surfaces of the colloid particle and the slab are assumed coated by thin layers exerting strong preference to the liquid phase of a simple fluid, or one of the components of a binary mixture, modeled by strong adsorbing local surface potentials, ensuring the so-called (+,+) boundary conditions. On the other hand, the core region of the slab and the particle, influence the fluid by long-ranged competing dispersion potentials. We demonstrate that for a suitable set of colloid-fluid, slab-fluid, and fluid-fluid coupling parameters the competition between the effects due to the coatings and the core regions of the objects, result, when one changes T or μ, in sign change of the Casimir force (CF) and the TF acting between the colloid and the slab. Such an effect can provide a strategy for solving problems with handling, feeding, trapping and fixing of microparts in nanotechnology.

Nitrobenzene Hydrogenation to N-phenylhydroxylamine: a New Approach to the Selectivity

A new approach to resolve the problem of selectivity with respect to N-phenylhydroxylamine in nitrobenzene hydrogenation is proposed. N-phenylhydroxylamine only is the final product of nitrobenzene electroreduction in aprotic media. In this case nitrobenzene reduction carries out by alternation of electrochemical (electron transfer) and chemical (species formed protonation) stages i.e. by so-called EC mechanism. Such mechanism realization in nitrobenzene hydrogenation is possible if i) a catalyst activates hydrogen as “hydrogen electrode” i.e. serves electrons source; ii) a reaction media contains limiting proton concentration. These limitations are discharged in the media of aprotic dipolar solvent, which solvated both positive and negative species. Really, in aprotic dipolar solvents over reduced platinum complexes or lowpercentage (≤1 wt.%) platinum, iridium or osmium catalyst nitrobenzene is hydrogenated with process discontinuance after nitrobenzene total consumption. Nitrobenzene hydrogenation yields N-phenylhydroxylamine as the main (the yield is 98%) product. As these low-percentage catalysts, complex catalyst in situ is heterogeneous i.e. it represents a platinum colloid (particle size ~ 40 nm) stabilized by aprotic dipolar solvent. So, process of nitrobenzene hydrogenation, which is similar to nitrobenzene electoreduction, can is created. A kinetic scheme proposed is analyzed and kinetic equation for initial reaction rate, which is conformed to kinetic data, is obtained.