Evaluation of a modified spray-applied interfacial polymerization method for preparation of nanofiltration membranes

Nanofiltration (NF) membranes were fabricated by using piperazine (PIP) and trimesoyl chloride (TMC) by conventional and spray-applied interfacial polymerization methods, studying the effect of the application method for both phases, the number of applied layers, and the displacement speed for the spray application. A polysulfone ultrafiltration membrane was used as support. NF membranes were characterized by different spectroscopic, microscopic, and physicochemical techniques. Rejection capacity was evaluated for sodium chloride (NaCl), sodium sulfate (Na₂SO₄), and magnesium sulfate (MgSO₄) salts; the decreasing rejection order was Na₂SO₄ > MgSO₄ > NaCl for each NF membrane. NF membrane prepared with one layer of the sprayed out TMC solution and conventional application of PIP solution exhibited the highest salt rejection (99% for 1000 ppm Na₂SO₄) and a permeated flux of 10.28 L m⁻² h⁻¹ at 0.55 MPa. The modified method is a facile-reproducible preparation methodology that reduces the consumption of time, effort, and reagents leading to a scalable manufacturing process for separation technology. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48129.     

Effect of morphology on the permeability,mechanical and thermal properties of polypropylene/SiO2 nanocomposites

Spherical silica nanoparticles with 20 and 100 nm diameters and organic‐template layered silica nanoparticles synthesized by the sol‐gel method were melt blended with a polypropylene (PP) matrix in order to study and quantify their effect on the oxygen and water vapor permeability and mechanical and thermal behavior. With regard to barrier properties, the spherical nanoparticles barely increased the oxygen permeability at low loads (≤10 wt%); meanwhile the layered nanoparticles dramatically increased it even at low loading (<5 wt%) probably due to the percolation effect. The changes in water vapor permeability were similar to those in oxygen permeability. The repulsive interaction between nanoparticles and PP forms interconnecting voids where the gas permeates. Tensile stress–strain tests showed that the composites present up to a 56% increase in the elastic modulus with spherical nanoparticles at 20 wt%, while layered nanoparticles show a decrease probably due to agglomerations and voids. Thermogravimetric analysis under inert conditions showed that the nanoparticles improved the PP thermal degradation process through the adsorption of volatile compounds on their surface, where the smaller spherical nanoparticles show the greatest stabilization. © 2015 Society of Chemical Industry     

Characterization of Ceramic‐Based Construction and Demolition Waste: Use as Pozzolan in Cements

Depending on its composition and properties, construction and demolition waste (C&DW) may be used today as recycled aggregate to manufacture more eco‐efficient concrete, for drainage or as a sub‐base in roads and on occasion as a decorative or esthetic element in pedestrian pathways in parks and landscaped grounds. In Spain, 54% of C&DW is ceramic‐based (CB‐C&DW). Since the use of such waste as recycled aggregate is not envisaged in Spanish legislation, it is presently stockpiled in landfills, an environmentally, technically, and economically detrimental procedure. The CB‐C&DW recycled at 12 Spanish waste management plants was assessed to determine the feasibility of its use as an alternative to pozzolans such as silica fume and fly ash presently added to cement during manufacture. The proportion of ceramic‐based material contained in this recycled waste varied from plant to plant. The effect of the ceramic‐based material content on the chemical and mineralogical composition, morphology, and pozzolanic activity of CB‐C&DW was explored in a more exhaustive study of two types of waste, one with 20 and the other with 100% ceramic‐based material content. In light of its chemical and mineralogical composition, morphology and lime fixation capacity, this type of C&DW was found to be apt for use as a pozzolan, and hence as a valid alternative for manufacturing more eco‐efficient cements.     

An evaluation of chondrocyte morphology and gene expression on superhydrophilic vertically-aligned multi-walled carbon nanotube films

Cartilage serves as a low-friction and wear-resistant articulating surface in diarthrodial joints and is also important during early stages of bone remodeling. Recently, regenerative cartilage research has focused on combinations of cells paired with scaffolds. Superhydrophilic vertically aligned carbon nanotubes (VACNTs) are of particular interest in regenerative medicine. The aim of this study is to evaluate cell expansion of human articular chondrocytes on superhydrophilic VACNTs, as well as their morphology and gene expression. VACNT films were produced using a microwave plasma chamber on Ti substrates and submitted to an O₂ plasma treatment to make them superhydrophilic. Human chondrocytes were cultivated on superhydrophilic VACNTs up to five days. Quantitative RT-PCR was performed to measure type I and type II Collagen, Sox9, and Aggrecan mRNA expression levels. The morphology was analyzed by scanning electron microscopy (SEM) and confocal microscopy. SEM images demonstrated that superhydrophilic VACNTs permit cell growth and adhesion of human chondrocytes. The chondrocytes had an elongated morphology with some prolongations. Chondrocytes cultivated on superhydrophilic VACNTs maintain the level expression of Aggrecan, Sox9, and Collagen II determined by qPCR. This study was the first to indicate that superhydrophilic VACNTs may be used as an efficient scaffold for cartilage or bone repair.     

Supporting different process views through a Shared Process Model

Different stakeholders in the business process management (BPM) life cycle benefit from having different views onto a particular process model. Each view can show, and offer to change, the details relevant to the particular stakeholder, leaving out the irrelevant ones. However, introducing different views on a process model entails the problem to synchronize changes in case that one view evolves. This problem is especially relevant and challenging for views at different abstraction levels. In this paper, we propose a Shared Process Model that provides different stakeholder views at different abstraction levels and synchronizes changes made to any view. We present detailed requirements and a solution design for the Shared Process Model. We also present an overview of our prototypical implementation to demonstrate the feasibility of the approach. Finally, we report on a comprehensive evaluation of the approach on real Business–IT modeling scenarios.     

Plasmonic Retrofitting of Membrane Materials: Shifting from Self‐Regulation to On‐Command Control of Fluid Flow

This work calls for a paradigm shift in order to change the operational patterns of self‐regulated membranes in response to chemical signals. To this end, the fabrication of a retrofitting material is introduced aimed at developing an innovative generation of porous substrates endowed with symbiotic but fully independent sensing and actuating capabilities. This is accomplished by transferring carefully engineered plasmonic architectures onto commercial microfiltration membranes lacking of such features. The integration of these materials leads to the formation of a coating surface proficient for ultrasensitive detection and “on‐command” gating. Both functionalities can be synergistically modulated by the spatial and temporal distribution of an impinging light beam offering an unprecedented control over the membrane performance in terms of permeability. The implementation of these hybrid nanocomposites in conventional polymeric porous materials holds great potential in applications ranging from intelligent fluid management to advanced filtration technologies and controlled release.     

Mechanisms of Solid–Gas Reactions: Reduction of Air Pollutants on Carbons

Topics in Catalysis - Ozone is a strong oxidizer and sulfur dioxide is a precursor to acid rain, both are air pollutants that can damage the respiratory tissues of animals and plants making them...     

Development and implementation of an FPGA based fractional order controller for a DC motor

Fractional calculus has been gaining more and more popularity in control engineering in numerous fields, including mechatronic applications. One of the most common applications in all mechatronic domains is the control of DC motors. Several control algorithms have been proposed for such motors, ranging from traditional PID algorithms, to the more sophisticated advanced methods, including fractional order controllers. Nevertheless, very little information regarding the implementation problems of such fractional algorithms exists today. The paper proposes a simple approach for designing a fractional order PI controller for controlling the speed of a DC motor. The resulting controller is implemented on an FPGA target and its performance is compared to other possible benchmarks. The experimental results show the efficiency of the designed fractional order PI controller. Beside the initial DC motor, two other different DC motors are also used in the experiments to demonstrate the robustness of the controller.     

The influence of SiMn slag on chemical resistance of blended cement pastes

During the last decades, industrial by-products and wastes recycling as complementary building materials is focusing a large number of researching studies, most of them dedicated to the cement and concrete production, studying technical, economical and environmental aspects.This paper presents an original contribution to this tendency, which consists on the possibility of recycling a SiMn slag from ferroalloys industry as a complementary construction material and its influence on the resistance of cement paste in different aggressive solutions. Different parameters, such as waste nature, additions, mechanical resistance, different aggressive solutions or morphological and microporosity changes were investigated. The results have showed that blended cement pastes elaborated with SiMn slag (5% and 15% additions) after 56 days of curing have a good resistance in some aggressive solutions, no losing weight and presenting an excellent resistance index compared to the reference matrix. Aggressive solutions presence do not alter elaborated pastes microporosity not minding if they are prepared with and without SiMn slag additions in the working conditions studied in this study.     

Use of clay-based construction and demolition waste as additions in the design of new low and very low heat of hydration cements

In light of the large amounts of cement used in plain concrete and given the exothermal reactions involved in its hydration, the control and assessment of heat of hydration are instrumental to prevent future shortcomings in structural durability. This article describes the design of new eco-efficient cements containing different percentages of fired clay-based construction and demolition waste (CC&DW). The new cements (CCDWC) were characterised for pozzolanicity and their heat of hydration was assessed based on a semi-adiabatic method described in European standards. The inclusion of CC&DW retarded the heating of mortar and lowered its maximum temperatures, more significantly with the increase of replacement ratios. The design of such CC&DW-bearing low and very low heat of hydration cements may well prompt the introduction of new applications of bulk cement or cement-high mixes, in which heat may have adverse effects on durability.