Sharif Digital Repository

Two-dimensional MXenes are the newly emerging family of nanomaterials with competitive performance for nano-device development. Surface functional groups and abundant binding sites make these materials ideal candidates for sensor applications. Herein, we report the successful fabrication of a MXene-based nano-bio device for capturing, sensing, and filtering the Escherichia coli (E. coli) bacteria. Mannose carbohydrate, which binds strongly to E.coli's fimH protein via glucan multivalent interactions, is used as the bio-receptor element. MXene's structure was engineered to guarantee efficient E. coli capturing without mannose detachment. Electrochemical impedance spectroscopy (EIS) and cyclic... 

BACKGROUND: The clay treatment widely utilized to reduce unsaturated components in aromatic stream has a detrimental effect on catalyst lifetime. Due to the short lifetime of commercial clay, a huge number of studies have been carried out to address this problem over the last decade. This study aims to optimize the temperature for longer serviceability of clay by removal of unsaturated aliphatic components from aromatic streams through the adsorption and catalytic properties of clay. A novel process arrangement is introduced by scheduling the reuse of deactivated clay that is discarded after deactivation. RESULTS: Results showed that the suitable range of temperature for olefin removal is... 

A new distributed observer-based output feedback control design with an arbitrary control structure is proposed. Assuming that the linear time-invariant (LTI) system does not have any fixed-modes with respect to the control structure, the pole placement at the desired locations becomes theoretically feasible. In this paper, the structural output feedback controller design is transformed into equivalent problems based on a graph-theoretic approach. Two augmented structures are established and formulated as the solution of a set of binary linear programs (BLP). The first one facilitates the incorporation of the maximum number of edges in the principal bipartite graph and the second one results... 

Injectable hydrogels which mimic the physicochemical and electromechanical properties of cardiac tissue is advantageous for cardiac tissue engineering. Here, a newly-developed in situ forming double-network hydrogel derived from biological macromolecules (oxidized alginate (OA) and myocardial extracellular matrix (ECM)) with improved mechanical properties and electrical conductivity was optimized. 3-(2-aminoethyl amino) propyltrimethoxysilane (APTMS)-functionalized reduced graphene oxide (Amine-rGO) was added to this system with varied concentrations to promote electromechanical properties of the hydrogel. Alginate was partially oxidized with an oxidation degree of 5% and the resulting OA... 

This article investigates the robustness of strong structural controllability for linear time-invariant and linear time-varying directed networks with respect to structural perturbations, including edge deletions and additions. In this direction, we introduce a new construct referred to as a perfect graph associated with a network with a given set of control nodes. The tight upper bounds on the number of edges that can be added to, or removed from a network, while ensuring strong structural controllability, are then derived. Moreover, we obtain a characterization of critical edge sets, the maximal sets of edges whose any subset can be respectively added to or removed from a network while... 

Three-dimensional porous nanocomposites consisting of gelatin-carboxymethylcellulose (CMC) cross-linked by carboxylic acids biopolymers and monophasic hydroxyapatite (HA) nanostructures were fabricated by lyophilization, for soft-bone-tissue engineering. The bioactive ceramic nanostructures were prepared by a novel wet-chemical and low-temperature procedure from marine wastes containing calcium carbonates. The effect of surface-active molecules, including sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (CTAB), on the morphology of HA nanostructures is shown. It is demonstrated that highly bioactive and monophasic HA nanorods with an aspect ratio > 10 can be synthesized in... 

Herein, some (modified) paper–based substrates were prepared and utilized as extractive phases in a microfluidic device and their extraction performances examined for analytes with different polarities. Reagents including hexadecyltrimethoxysilane (HDTMS), phenyltrimethoxysilane (PTES), (3-aminopropyl) triethoxysilane (APTES) and 3–(2,3–epoxypropoxy) propyltrimethoxysilane (EPPTMOS) were implemented for the modification process. Due to the induction of different silane functional groups, it was anticipated to have various interactions for the tested analytes. Eventually, the prepared paper sheets were used as extractive phases for solid–phase extraction within a microfluidic system. The... 

Wind and ocean waves highly influence the performance and functionality of structures, requiring an efficient control element. The structural behavior of one of the most recent structural control elements, namely shape memory alloys (SMA)-based control element, under cyclic loadings of oceans waves, has been investigated. Shape memory alloys are one of the attractive smart materials with the ability to return to the initial shape after experiencing large deformation. Experimental tests have been conducted to study the effects of cyclic loads on several specimens of the SMA wires. The SMA wires are being used in the SMA-based structural control system to dissipate the energy of external... 

The stability and integrity of structures under indeterminant external loadings, particularly earthquakes, is a vital issue for the design and safe operation of marine and offshore structures. Over the past decades, many structural control systems, such as viscous-based systems, have been developed and embedded in marine and offshore structures, particularly oil platforms to maintain the stability and mitigate the seismic hazards. Rapid improvement in intelligent materials, including shape memory alloys (SMAs) and Magnetorheological fluid (MRF), have led to the design and development of efficient structural control elements. The present work aims to establish a framework for the structural... 

Structural integrity and ensuring the stability of steel frame structures, including marine and coastal structures, are the main challenges for designers in civil infrastructures, particularly in oil platforms, subjected to tough periodic and non-periodic environmental loading conditions. Variable loadings with different amplitudes and frequencies may lead to the stability of steel structures loss. In order to keep the stability of the steel structures and prevent possible damages, reliable yet efficient structural control systems are in demand. Conventional structural control systems need significant activation energy and/or in-depth users knowledge to be effective. Most recently, smart... 

Dynamic environmental loads, such as winds and waves, make the stability of offshore structures at high risk, requiring reliable yet efficient control elements to ensure the stability of such structures under lateral loads. Among the variety of control elements that have been developed to enhance the stability of a structure, shape memory alloy (SMA)-based control elements are promising as they are low-cost, easy to embed into the main control element, and do not need an external power supply. However, cyclic loads may highly influence the performance and functionality of SMA-based elements. The present work investigates the effects of pre-straining SMA components in energy dissipation... 

Lysozyme loaded niosomes containing various molar ratios of two kinds of surfactants were prepared and the properties of these niosomal formulations were studied. The results revealed that the size of niosomes varied between 240.06 ± 32.41 and 895.2 ± 20.84 nm. Formulations with the lowest size and no precipitation had entrapment efficiencies ranging from 60.644 ± 3.310 to 66.333 ± 1.98%. Their controlled release profiles after 48 h were 15.67, 20.67 and 31.50%. After 2 months, the most stable formulation in terms of size, PDI, zeta potential, and entrapment efficiency was used to study the secondary structures of lysozyme in niosomal and free forms. Lysozyme loaded niosome and lysozyme... 

In this paper, we discuss the controllability of a family of linear time-invariant (LTI) networks defined on a signed graph. In this direction, we introduce the notion of positive and negative signed zero forcing sets for the controllability analysis of positive and negative eigenvalues of system matrices with the same sign pattern. A sufficient combinatorial condition that ensures the strong structural controllability of signed networks is then proposed. Moreover, an upper bound on the maximum multiplicity of positive and negative eigenvalues associated with a signed graph is provided. © 2019 IEEE  

Marine structures, as key elements in the global energy network, constantly are subjected to harsh environmental loading conditions. Therefore, reliable yet efficient structural control mechanisms are required to ensure their safe functionality and structural stability. In the present work, a novel hybrid structural control element for marine structures has been designed in which the superelasticity effect of shape memory alloy (SMA) and damping controllability of magnetorheological fluid (MRF), as smart materials, have been combined. The novel system does not require huge external energy for activation and in addition, the system has the ability to be tuned for variable loading conditions.... 

CuFeO2/CeO2 as a novel synergistic catalyst for EF removal of organic pollutants was synthesized. © 2019 Elsevier Ltd  

To enhance physicomechanical properties and bioactivity of fibrous membranes for wound dressing and tissue engineering applications, novel composite scaffolds consisting of fibrous mats and thermosensitive hydrogel particles were prepared by concurrent electrospinning and electrospraying technique. The composite scaffolds were composed of keratin/bacterial cellulose fibers (150 ± 43 nm) which are hybridized with hydrogel particles (500 nm to 2 μm) based on nonionic triblock copolymers conjugated with Tragacanth gum (TG). FTIR and H-NMR studies indicated ester reactions between carboxylated copolymers and TG through carbodiimide crosslinker chemistry. The hydrogel particles were uniformly... 

The planned design of nanocomposites combined with manageable production processes, which can offer controllability over the nanomaterial structure, promises the practical applications of functional nanomaterials. Hollow core-shell nanostructure architectures represent an emerging category of advanced functional nanomaterials, whose benefits derived from their notable properties may be hampered by complicated construction processes, especially in the sensing domain. In this regard, we designed a highly porous three-dimensional array of hierarchical hetero Cu(OH)2@CoNi-LDH core-shell nanotubes via a quick, very simple, green, and highly controllable three-step in situ method; they were... 

ABSTARCT: A practical procedure is developed for the design of passive control systems using viscous fluid dampers for nonlinear structures. The design methodology takes advantage of the modification of the damping, strength, and stiffness properties of the structure to achieve the desired relative displacement and absolute acceleration response. For this purpose, a study of poles in the complex plane is used to determine the required changes in the dynamic properties of nonlinear structures. Furthermore, a relatively simple relation between the ductility demands of highly damped single- and multiple-degree-of-freedom (SDF and MDF respectively) systems is established to reduce the... 

This paper presents a new robust control strategy for islanded operation of a microgrid consisting of several distributed generation (DG) units with arbitrary topology. Each DG unit is connected to its local load through a voltage-source converter, a series RL filter and a step-up transformer. The multi-DG microgrid with arbitrary connectivity graph is modeled as a linear time-invariant system subject to a parametric, norm-bounded uncertain block. By utilizing the developed model for multi-DG microgrids, a systematic approach for the design of structured dynamic output feedback control is proposed. A convex optimization problem is developed which yields a low-order dynamic controller of... 

Highly dynamic nature of the applied loads on flexible and lightly damped offshore wind turbine (OWT) foundations affects the lifetime and serviceability of the system. In this study, the excessive vibration responses of OWTs are minimized using tuned mass dampers (TMD) and tuned liquid column dampers (TLCD). Due to high efficiency of TLCDs and TMDs for certain loading conditions, a combined TLCD-TMD is also utilized to improve the overall performance in a wide range of loading conditions. First, a parametric study was performed that highlights the sensitivity of these structural control devices. The effect of two devices on fixed offshore wind turbine foundations for the benchmark 5 MW NREL...