Muhammad Nabeel Anwar

Preparation of antibacterial cotton fabric using chitosan-silver nanoparticles

The aim of this study was to prepare antibacterial cotton fabric using chitosan-silver nanoparticles (CS-AgNPs). CS-AgNPs were used as finishing agent for 100 % pure cotton fabric. AgNPs were prepared by Turkevich method. CSAgNPs were synthesized by mixing chitosan solution with silver nanoparticles. Fourier transform infrared (FTIR) spectrometer technique supported the formulation of CS-AgNPs. Cs-AgNPs crystalline peaks were in perfect agreement with JCPDS card no. 89-3722. Two gram negative bacteria Escherichia coli, Pseudomonas aeruginosa and two gram positive bacteria Bacillus cereus, Staphylococcus aureus were used to test the bacterial efficacy of synthesized AgNPs and CSAgNPs. Scanning electron micrograph of cotton fabric revealed the presence of CS-AgNPs on the surface of cotton fabric. The presence of small amount of silver nanoparticles in the composite was enough to enhance antibacterial activity significantly compared to pure chitosan.

Neural dynamics in motor preparation: From phase-mediated global computation to amplitude-mediated local computation

Oscillatory activity plays a critical role in the brain. Here, we illustrate the dynamics of neural oscillations in the motor system of the brain. We used a non-directional cue to instruct participants to prepare a motor response with either the left or the right hand and recorded electroencephalography during the preparation of the response. Consistent with previous findings, the amplitude of alpha-band (8-14Hz) oscillations significantly decreased over the motor region contralateral to the hand prepared for the response. Prior to this decrease, there were a number of inter-regional phase synchronies at lower frequencies (2-4Hz; delta band). Cross-frequency coupling was quantified to further explore the direct link between alpha amplitudes and delta synchrony. The cross-frequency coupling of showed response-specific modulation, whereby the motor region contralateral to the preparation hand exhibited an increase in coupling relative to the baseline. The amplitude of alpha oscillations had an unpreferred and a preferred delta phase, in which the amplitude was modulated negatively and positively, respectively. Given the amplitude of alpha-band oscillations decreased over the analyzed period, the alpha amplitude might be down-regulated by the phase-amplitude coupling, although we do not have direct evidence for that. Taken together, these results show global-to-local computation in the motor system, which started from inter-regional delta phase synchrony and ended at an effector-specific decrease in the amplitude of alpha-band oscillations, with phase-amplitude coupling connecting both computations.

Motor imagery facilitates force field learning.

Humans have the ability to produce an internal reproduction of a specific motor action without any overt motor output. Recent findings show that the processes underlying motor imagery are similar to those active during motor execution and both share common neural substrates. This suggests that the imagery of motor movements might play an important role in acquiring new motor skills. In this study we used haptic robot in conjunction with motor imagery technique to improve learning in a robot-based adaptation task. Two groups of subjects performed reaching movements with or without motor imagery in a velocity-dependent and position-dependent mixed force field. The groups performed movements with motor imagery produced higher after effects and decreased muscle co-contraction with respect to no-motor imagery group. These results showed a positive influence of motor imagery on acquiring new motor skill and suggest that motor learning can be facilitated by mental practice and could be used to increase the rate of adaptation.

A review of techniques for detection of movement intention using movement-related cortical potentials

The movement-related cortical potential (MRCP) is a low-frequency negative shift in the electroencephalography (EEG) recording that takes place about 2 seconds prior to voluntary movement production. MRCP replicates the cortical processes employed in planning and preparation of movement. In this study, we recapitulate the features such as signals acquisition, processing, and enhancement and different electrode montages used for EEG data recoding from different studies that used MRCPs to predict the upcoming real or imaginary movement. An authentic identification of human movement intention, accompanying the knowledge of the limb engaged in the performance and its direction of movement, has a potential implication in the control of external devices. This information could be helpful in development of a proficient patient-driven rehabilitation tool based on brain-computer interfaces (BCIs). Such a BCI paradigm with shorter response time appears more natural to the amputees and can also induce plasticity in brain. Along with different training schedules, this can lead to restoration of motor control in stroke patients.

Synergistic effect of Chitosan-Zinc Oxide Hybrid Nanoparticles on antibiofouling and water disinfection of mixed matrix polyethersulfone nanocomposite membranes

Antifouling polyethersulfone (PES) membranes for water disinfection were fabricated by incorporating varying concentrations of carbohydrate polymer chitosan and Zinc oxide hybrid nanoparticles (CS-ZnO HNPS). The CS-ZnO HNPS were prepared using chemical precipitation method and were characterized using SEM, XRD and FTIR. The membranes were then fabricated by incorporating nanoparticles of CS-ZnO HNPS with three different concentrations of 5%, 10% and 15% w/w in the casting solution of PES through phase inversion method. The influence of nano-sized CS-ZnO HNPS on the properties of PES was characterized to study morphology, contact angle, water retention, surface roughness and permeability flux. The membranes with the maximum concentrations of 15% HNPS resulted in larger mean pore sizes and lowest contact angle value as compare to the pristine PES membrane. The prepared membranes exhibited significant water permeability, hydrophilicity and prevention against microbial fouling. The prepared membranes were observed to have significant antibacterial as well as antifungal properties due to the synergistic effect of chitosan and ZnO against both bacteria of the type of S. Aureus, B. Cereus, E. coli, and fungi such as S. typhi, A. fumigatus and F. solani.

Motor imagery in robot-assistive rehabilitation: A study with healthy subjects

Robots have been extensively used to study the adaptive properties of the human motor system. If robots are used in conjunction with techniques for functional brain imaging, in principle the motor learning can be facilitated for rehabilitation purposes. A technique that speeds up the learning process would find immediate application in fields like motor skill acquisition in normal subjects and maximization of motor recovery in stroke patients. In this study, we use motor imagery based real-time EEG recording as a bio-feedback technique to improve the learning rate in a robot-based adaptation task. The results suggest that, the motor learning can be influenced by mental practice and could be used to increase the rate of adaptation.

Trial-by-Trial Adaptation of Movements during Mental Practice under Force Field

Human nervous system tries to minimize the effect of any external perturbing force by bringing modifications in the internal model. These modifications affect the subsequent motor commands generated by the nervous system. Adaptive compensation along with the appropriate modifications of internal model helps in reducing human movement errors. In the current study, we studied how motor imagery influences trial-to-trial learning in a robot-based adaptation task. Two groups of subjects performed reaching movements with or without motor imagery in a velocity-dependent force field. The results show that reaching movements performed with motor imagery have relatively a more focused generalization pattern and a higher learning rate in training direction.

Online detection and classification of movement kinetics

Over the past years brain-computer interface (BCI) technology has been proposed as a means for neurorehabilitation. To induce Hebbian-associated-like plasticity, the movement-related cortical potential (MRCP) can be detected from the continuous brain activity to trigger timely appropriate inflow of somatosensory feedback from electrical stimulation. The aim of this study was to detect the MRCP online from the continuous brain activity and decode two types of movements that were performed with different levels of force and speed (2x50 movements). 5 healthy subjects and 1 stroke patient performed/attempted to perform the movements. The system correctly detected and classified 65±3 % and 51 % of the movements for the healthy subjects and patient, respectively. The findings suggest that it is possible to detect movements and decode kinetic information online. This may have implications for stroke rehabilitation where task variability may be introduced to optimize the retention of relearned movements.

Influence of motor imagery on learning under complex external dynamics

Humans are remarkable in their ability to adapt to changes in the dynamics of a movement. The mechanisms by which the brain controls body movements are important in the fields of robotics and neurosciences. Robots are largely used to study the adaptive properties of human motor system. If rehabilitation robots are used in conjunction with techniques for functional brain imaging, in principle the motor learning can be facilitated for rehabilitation purposes. In this study, we use motor imagery technique to improve the learning rate in a robot-based adaptation task. We tried to determine whether humans can learn an internal model of a complex mixed force field (V+P) that was the sum of a velocity-dependent force field (V) and a position-dependent force field (P). The results suggest that the motor learning can be influenced by mental practice and could be used to increase the rate of adaptation.

Performance feedback assists practice driven plasticity

Motor skills are generally acquired by means of practice. This procedure comprised of acquiring particular task requirements by overruling intrinsic tendencies. The objectives of the present study were; to induce plasticity through bimanual finger tapping task; and to determine the influence of presence or absence of performance feedback on training. Behavioural data from 16 healthy subjects was recorded. They were randomly divided into two equal groups. First group performed bimanual finger tapping task according to 2∶1 mode with feedback (TF). Second group performed bimanual finger tapping task according to 2∶1 mode without feedback (TNF). All subjects performing Tapping task either with or without feedback improved their performance at the end of practice. However, TF performed better than TNF, F (1,14) = 22.378, p<0.01. The results illustrate that practice of 2∶1 task with feedback leads to augmented motor experience reflecting better practice driven plasticity.