Rapid self-healing and triple stimuli responsiveness of a supramolecular polymer gel based on boron-catechol interactions in a novel water-soluble mussel-inspired copolymer

Vatankhah-Varnoosfaderani, M.,Hashmi, S.,GhavamiNejad, A.,Stadler, F. Royal Society of Chemistry 2014 Polymer chemistry Vol.5 No.2

Marine and freshwater mussels secrete proteinaceous adhesive materials for adherence to the substrates upon which they reside. It is well known that 3,4-dihydroxyphenylalanine (DOPA) is the key to understanding these mussel adhesive proteins (MAPs). In order to gain a better understanding of their complex formation and quick recovery upon rupturing, novel water soluble copolymers of N-isopropylacrylamide and dopamine methacrylate were synthesized in such a way that they have 1, 2.5, and 5 mole percent dopamine monomer with respect to the NIPAM monomer on average. The statistical distribution of DOPA-functionalities along the chain makes the material a close synthetic equivalent of the byssal thread proteins of mytili. At acidic pH, the aqueous copolymer solution behaves like an unentangled copolymer solution, but at basic pH, these catechol functionalities form a dicomplex with H3BO3, thereby crosslinking two chains, proven by B-11-NMR and gelation. The polymer solution is thermosensitive with a pH-dependent lower critical solution temperature (LCST) between 21 and 33 degrees C, depending on the DOPA-content. If 2 or more functionalities per chain are present, a gel is formed that is self-healing with very quick recovery from sustained damage. The moduli of the gels depend on the concentration of functionalities. Hence, triple stimuli responsive copolymers were obtained.

Mussel-inspired pH-triggered reversible foamed multi-responsive gel – the surprising effect of water

Vatankhah-Varnoosfaderani, Mohammad,GhavamiNejad, Amin,Hashmi, Saud,Stadler, Florian J. The Royal Society of Chemistry 2013 Chemical communications Vol.49 No.41

<P>Novel covalent gels were prepared by complexation of polymer-bound catechols with NaBH<SUB>4</SUB> at pH ≈ 9. These gels can absorb humidity, which changes the catechol–borate covalent bonds from irreversible to reversible. Furthermore, humidity induces self-healing, proven by rheological data.</P> <P>Graphic Abstract</P><P>Humidity induced sol–gel reversibility and improved self-healing behavior of a novel supramolecular organogel produced by complexation of catechol with NaBH<SUB>4</SUB>. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3cc41332b'> </P>

Genetic and Non-genetic Factors Affecting Mortality in Lori-Bakhtiari Lambs

Vatankhah, M.,Talebi, M.A. Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.4

Data and pedigree information for Lori-Bakhtiari sheep used in this study were 6,239 records of lamb mortality from 246 sires and 1,721 dams, collected from 1989 through 2007 from a Lori-Bakhtiari flock at Shooli station in Shahrekord. The traits investigated were cumulative lamb mortality from birth up to 7 days, up to 14 days, up to 21 days, and up to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12 months of age. The models included fixed factors that had significant effects and random direct genetic, maternal genetic and maternal permanent environmental effects. Variance components were estimated using the restricted maximum likelihood procedure applying three animal models with and without maternal and common environmental effects. The overall mean of cumulative lamb mortality rate was 22.95% from birth to 1 year of age, while the overall mortality rate up to 3 and from 3 to 6 months of age was 6.14% and 12.76%, respectively. The mortality rate after 6 months of age declined as the lambs grew older. The age of dam had no important effect on lamb mortality. The type of birth was more important during the preweaning period than at later ages, and lamb mortality rate was higher in twins. The year of birth, month of birth and sex of lamb significantly (p${\leq}$0.01) affected the cumulative lamb mortality rate at all ages. The least square mean of mortality during the final one-third of the lambing period was higher than the first and middle onethird of the lambing period. Male lambs were found to be at a higher risk of mortality than females. Birth weight of the lamb had a highly significant (p${\leq}$0.01) effect on lamb mortality at all ages as a quadratic regression. Direct and maternal heritability estimates of lamb mortality ranged from 0.01 to 0.13 and 0.01 to 0.05, respectively. Direct heritability increased with age of lamb, while maternal effects (genetic and common environmental) were important in the preweaning period. These results indicate that lamb mortality can be reduced first through farm management practices and secondly by genetic selection. Both animal and maternal effects should be considered in breeding programmes for reducing lamb mortality at preweaning.

Real-time Velocity Optimization of a Group of Autonomous Members via Ant Colony Optimization (ACO)

Ramin Vatankhah,Shahram Etemadi,Aria Alasty,Mehrdad Boroushaki,Gholamreza Vossoughi 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8

In this paper, the agent velocity in robotic swarm was determined by using Ant Colony optimization (ACO) algorithm to maximize the swarm center velocity. First briefly we present an analytical study of swarm motion in a quasi static environment, in which, motion of each member is being affected by interactive forces and an agent. Interactive effects on each member could be attractive or repulsive due to being far from or close to other members respectively. It is also considered that field of view of all members is limited, i.e. even the agent accesses its local information. Ant colony algorithm is a mathematical model of ants" behaviour in finding the shortest path between nest and food. The agent velocity in robotic swarm was determined by using ACO to maximize the swarm center velocity. The results show the high ability of this evolutionary algorithm in solving complicated dynamic optimization problems.

Asymptotic decay rate of non-classical strain gradient timoshenko micro-cantilevers by boundary feedback

Ramin Vatankhah,Ali Najafi,Hassan Salarieh,Aria Alasty 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.2

In non-classical micro-beams, the strain energy of the system is obtained based on the non-classical continuum mechanics. This paperpresents the problem of boundary control of a vibrating non-classical micro-cantilever Timoshenko beam to achieve the asymptotic decayrate of the closed loop system. For this aim, we need to establish the well- posedness of the governing partial differential equations(PDEs) of motion in presence of boundary feedbacks. A linear control law is constructed to suppress the system vibration. The controlforces and moments consist of feedbacks of the velocities and spatial derivatives of them at tip of the micro-beam. To verify the effectivenessof the proposed boundary controllers, numerical simulations of the open loop and closed loop PDE models of the system areworked out using finite element method (FEM). New Timoshenko beam element stiffness and mass matrices are derived based on thestrain gradient theory and verification of this new beam element is accomplished.

Usability Measurement of Malaysian Online Tourism Websites

Najmeh Vatankhah,Koh Tieng Wei,Sukumar Letchmunan 보안공학연구지원센터 2014 International Journal of Software Engineering and Vol.8 No.12

Tourism in Malaysia has huge potential as the country is rich with different kinds of attractions such as historical places, different kinds of festival to enjoy and beautiful scenery to embrace. With the advances of the Internet, many investors have begun to produce different websites to promote their product; however, the quality is still valued expeditiously. The purpose of this paper is to analyze and evaluate the quality of Malaysian tourism websites in terms of usability. With this aim, five different Malaysian tourism websites were selected and evaluated based on their effectiveness, efficiency and user satisfaction. This was done using a questionnaire based evaluation.

Discussion of “Application of Excel Solver for Parameter Estimation of the Nonlinear Muskingum Models” by Reza Barati

Ali R. Vatankhah 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.1

An accurate solution method is essential to the calibration of the nonlinear Muskingum model. Most of the earlier researchers haveused inaccurate Euler’s solution method which is manipulated to get a better fit for observed Wilson’s data (1974). Euler’s methodwhich is adopted by most previous researchers is not very accurate and results in unsuitable simulation based on the nonlinearMuskingum model as shown in this discussion. This study proposes fourth-order Runge-Kutta method as a suitable and accuratesolution method for simulation stage. When more accuracy is needed, the structure of the Muskingum model can be modified toproduce more degree of freedom in model calibration procedure. For this purpose, a new five-parameter nonlinear Muskingummodel is proposed. The proposed model is easy to formulate and use. The results show that the improvement in the fit of the proposednonlinear Muskingum model is substantial.

Limiting Dimensions for Trapezoidal Channels and Control Notches (Design Aid)

Ali R. Vatankhah 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.4

Determining the channel dimensions leading to critical flow conditions for given values of specific energy or specific force plays an important role in channel transition design. A closed-form analytical solution for the problem can only be derived for triangular,rectangular and parabolic channels. This is not possible, however, for other practical geometries, such as trapezoidal channels. The dimensions of the trapezoidal control notch are determined by simultaneously satisfying the critical state of flow and specific energy equation. At present, graphical solutions are used for design discharges less than 2.83 m3/s. In current study, direct solutions to compute the limiting dimensions of the trapezoidal channel and direct solutions to design of the trapezoidal control notch are derived. The proposed solutions are nearly exact and will be useful in the design and analysis of the trapezoidal channels and notches.

Fuzzy sliding‐mode control of a human arm in the sagittal plane with optimal trajectory

Fateme Fotouhi Ardakani,Ramin Vatankhah,Mojtaba Sharifi 한국전자통신연구원 2018 ETRI Journal Vol.40 No.5

Patients with spinal cord injuries cannot move their limbs using their intact muscles. A suitable controller can be used to move their arms by employing the functional electrical stimulation method. In this article, a fuzzy exponential sliding‐mode controller is designed to move a musculoskeletal human arm model to track an optimal trajectory in the sagittal plane. This optimal arm trajectory is obtained by developing a policy for the central nervous system. In order to specify the optimal trajectory between two points, two dynamic and static optimal criteria are applied simultaneously. The first dynamic objective function is defined to minimize the joint torques, and the second static optimization is offered to minimize the muscle forces at each moment. In addition, fuzzy logic is used to tune the sliding‐surface parameter to enable an appropriate tracking performance. Simulation results are evaluated and compared with experimental data for upward and downward movements of the human arm.

Supramolecular Interaction Controlled Diffusion Mechanism and Improved Mechanical Behavior of Hybrid Hydrogel Systems of Zwitterions and CNT

Hashmi, Saud,GhavamiNejad, Amin,Obiweluozor, Francis O.,Vatankhah-Varnoosfaderani, Mohammad,Stadler, Florian J. American Chemical Society 2012 Macromolecules Vol.45 No.24

<P>Hybrid hydrogels of poly(<I>N</I>-isopropylacrylamide) (pNIPAM) containing carboxylate carbon nanotubes (CNTs) and/or zwitterions are synthesized by free radical polymerization. The supramolecular interactions among zwitterionic monomers and CNTs influence the mechanical properties and diffusion mechanism in hybrid hydrogel systems. These supramolecular interactions and response behavior of hybrid hydrogels were tested mechanically and with respect to their swelling characteristics. Hybrid hydrogels of pNIPAM and CNT or pNIPAM, zwitterions, and CNT follow a Fickian diffusion behavior, while adding zwitterions leads to an anomalous triple-stage swelling behavior and stiffening of the gel due to the interactions of the zwitterions with each other, which significantly increase the viscous dissipation and change the microscopic structure. While CNT itself stiffens the gel and slightly increases the diffusion speed, it complexes zwitterions, which leads to a novel property profile that is both potentially antibiotic and electrically conductive. CNT affords a relaxation process at long relaxation times, while zwitterion attachment and detachment lead to dissipation predominantly at high frequencies. Dynamic rheological measurements were performed during swelling of these complex materials.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/mamobx/2012/mamobx.2012.45.issue-24/ma301366h/production/images/medium/ma-2012-01366h_0014.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ma301366h'>ACS Electronic Supporting Info</A></P>