Gas‐phase flow resistance of metal foams: Experiments and modeling

Based on experimental results of gas flow resistance through two metal foams, NC 2733 and Ni 2733, a modeling is performed to adjudicate governing flow mechanism. Two essential models are considered: developing laminar flow within short capillary channel (i.e., foam pore) and flow around solid body (foam strut modeled as cylinder or sphere), each of them of some variants. Foam geometry was studied using computer microtomography. The model of flow around a sphere (diameter equal to strut thickness) gives the best conformity with experiments. © 2017 American Institute of Chemical Engineers AIChE J, 63: 1799–1803, 2017     

Purification of flowback fluids after hydraulic fracturing of Polish gas shales by hybrid methods

ABSTRACT

Hydraulic fracturing is a process that is used for the stimulation of impermeable rocks in order to release the trapped natural gas. Flowback fluid contains many different chemical ingredients used in the fracturing process; it also holds compounds leached from the bedrock. The production of a large amount of toxic fluids leads to the necessity of purification for recycling to reduce environmental impact. In this paper, the results of studies on the purification of flowback fluids by the combination of various processes such as filtration, advanced oxidation, and ion exchange are presented. The technological scheme of the treatment is proposed.     

Silica functionalized by pyridinecarboximidamides as a novel sorbent of heavy metals ions

ABSTRACT

Two novel sorbents, obtained as a result of surface modification of silica gel for the Cu(II), Co(II) and Ni(II) removal from aqueous solutions were proposed. For the modification, 3-chloropropyltrimethoxysilane, N’-hydroxy-N,N-dioctylpyridine-3-carboximidamide and N’-hydroxy-N,N-dioctylpyridine-4-carboximidamides were used. A series of basic tests on the sorption of Cu(II), Co(II) and Ni(II) were carried out and the presented results indicated that the novel sorbents were able to remove all tested metals ions from the aqueous solutions, and the removal efficiency was dependent on the functionalised agent structure, dosage, metal ions concentration and pH. The Langmuir model also assumed that a monolayer sorption occurred.     

Pasta Fortified with Potato Juice: Structure,Quality, and Consumer Acceptance

The potential of potato juice in relieving gastrointestinal disorders has already been proven. Work continues on implementation of this active component into products that are widely consumed. In this article, results of an attempt to fortify pasta with potato juice are presented and discussed. Fortification is performed using fresh and dried juice. The influence of the addition on culinary properties of the final product, such as cooking weight and cooking loss, as well as microstructure, color, texture, and consumer acceptance were evaluated. It was found that potato juice can be used for fortification of pasta both in its fresh and dried forms, however the effects on different responses depend on the potato juice form used. The addition of potato juice influenced the color of the product reducing its lightness and shifting color balances from green to red, yellow color saturation was decreased as well. Changes in color were more significant in the case of fresh juice addition. The firmness and microstructure of pasta was also influenced. The surface microstructure of pasta containing fresh potato juice was different from that of the other 2 products being a likely explanation of the lower cooking loss observed in its case. In contrast, the consistency of dough was strengthened by addition of dried potato juice. Principal components analysis indicated that the color change had the most pronounced effect on consumer acceptance. Other physicochemical changes were slightly less significant. Nevertheless, sensory evaluation proved that functional pasta produced with fresh potato juice finds consumer acceptance comparable with that of classic pasta.     

The mathematical models of the stripping voltammetry metal deposition/dissolution process

Three mathematical models of electrochemical two-electron deposition/dissolution process have been presented and discussed. The advanced two-plate model with BET adsorption formula equation has been presented and verified by the use of the experimental Cu²⁺/Cu⁺/Cu⁰ system in 0.5 M HCl solution at different scan rates. A change of electrode properties during electrode process was included into applied model and discussed.     

Modified set-point controller for underwater vehicles

A modified PD (proportional-derivative) controller for autonomous underwater vehicles (AUVs) is presented in this paper. The controller is expressed in terms of first-order equations of motion with a unit inertia matrix. The main difference between the proposed controller and the classical one relies on that the dynamics of the system is taken into account. This property ensures fast error and force convergence to the end-value. The PD controller can be applied for fully actuated AUVs. It is worth noting that the regulator gain matrices are selected based on parameters of the tested vehicle. The stability of the presented control law is proved in the sense of Lyapunov. Moreover, some advantages and observations resulting from the use of the controller are given. The performance of the controller is shown via simulations on a 6-DOF underwater vehicle.     

Crowd dynamics – being stuck

We consider a crowd of N persons trying to leave some area trough a small exit. The probability is calculated that an individual is able to withdraw from the crowd under one?s own steam. The problem is simulated within the generalized force model (D. Helbing, et al., Nature 407 (2000) 487), and all model parameters are taken from this paper. The results indicate, that in a crowd of 150 persons, this probability is not greater than ten percent. We also evaluate the number of helpers necessary to get the above probability of fifty percent.     

Development of microfibers for bone regeneration based on alkali-free bioactive glasses doped with boron oxide

In this paper, we present a new series of alkali-free bioactive glasses (BG) based on FastOs^® composition (38.49 SiO₂ – 36.07 CaO – 19.24 MgO – 5.61 P₂O₅ – 0.59 CaF₂, expressed in mol %), which was modified by partially replacing silicon dioxide network-former with boron trioxide network-former, utilizing calcium oxide as a charge compensator. The main objective of this study was to obtain a new family of bioactive glasses suitable for the fabrication of glass fibers. The BGs were prepared by melt quenching technique and their structural and thermal properties were determined. Glass rods were used to obtain fibers by the classic drawing technique. The bioactivity of the fibers was subsequently assessed through immersion tests in simulated body fluid (SBF) to establish their ability to form hydroxyl carbonated (HCA) apatite onto their surfaces. Glasses with moderate substitution of SiO₂ with B₂O₃ exhibited enhanced thermal properties, allowing to significantly suppress the crystallization trend, and favoring to draw the fibers. The structure of the studied glasses was obtained by NMR spectroscopy. The structure-property correlations were established by their relationship to the configurational entropy. Smaller amounts of substitution resulted in larger entropy of the glasses. Moreover the SBF tests revealed an extensive formation of HCA, comparable to the parent FastOs^®BG composition, which assures fast bonding to the bone. Thus, presented glass fibers may be considered as promising materials for wool-like bone implants or as reinforcing constituent of biopolymer matrix composites.