Sharif Digital Repository

Veronica genus (Plantaginaceae) is broadly distributed in different habitats. In this study, the inhibitory activity of free soluble and conjugated phenolic extracts of Veronica persica on key enzymes associated to type 2 diabetes (α-glucosidase and α-amylase) and hypertension (angiotensin I converting enzyme, ACE) was assessed, as well as their antioxidant power. Our results showed that both the extracts inhibited α-amylase, α-glucosidase and ACE in a dose-dependent manner. In particular, free phenolic extract significantly (P < 0.05) inhibited α-glucosidase (IC50 532.97 μg/mL), whereas conjugated phenolic extract significantly (P < 0.05) inhibited a-amylase (IC50 489.73 μg/mL) and ACE... 

Interaction between rock-fluid and fluid-fluid can have a significant effect on oil recovery. Changing the wettability of reservoir rock toward more water-wet or less oil-wet state is one of the expected mechanisms during low salinity water injection (LSWI). pH and salinity are of the most eminent factors of injection water controlling the wettability state of a crude oil/brine/rock system during any waterflooding operation. A small change in pH can affect the surface charges at the rock/water and oil/water interfaces leading to wettability alteration in a porous medium. In this study, the synergic effect of salinity and pH on the wettability state of carbonate rocks is evaluated through... 

Optimal trajectory and muscle forces of a human-like musculoskeletal arm are predicted for planar point-to-point movements using optimal control theory. The central nervous system (CNS) is modeled as an optimal controller that performs a reaching motion to final states via minimization of an objective function. For the CNS strategy, a cubic function of muscles stresses is considered as an appropriate objective function that minimizes muscles fatigue. A two-DOF nonlinear musculoskeletal planar arm model with four states and six muscle actuators is used for the evaluation of the proposed optimal strategy. The nonlinear variational formulation of the corresponding optimal control problem is... 

In this work, cycling-induced aging occurring in 18650-type LiFePO4/graphite full cells at different C-rates is studied extensively. The mechanism of performance degradation is investigated using a combination of electrochemical and microstructural analyses. Half-cell studies are carried out after dismantling the full cells, using fresh and cycled LiFePO4 cathode and graphite anode to independently study them. The results show that the capacity of LiFePO4 electrodes is significantly recovered. The rate of capacity fading in the discharge state considered as irreversible capacity in the graphite is higher than LiFePO4 half cells, indicating a greater degradation in the performance of this... 

In this work, cycling-induced aging occurring in 18650-type LiFePO4/graphite full cells at different C-rates is studied extensively. The mechanism of performance degradation is investigated using a combination of electrochemical and microstructural analyses. Half-cell studies are carried out after dismantling the full cells, using fresh and cycled LiFePO4 cathode and graphite anode to independently study them. The results show that the capacity of LiFePO4 electrodes is significantly recovered. The rate of capacity fading in the discharge state considered as irreversible capacity in the graphite is higher than LiFePO4 half cells, indicating a greater degradation in the performance of this... 

In recent years, controlling the salinity and composition of the injected water has become an emerging enhanced oil recovery (EOR) technique, often described as low salinity (LS) waterflooding. This work is done with the intention to contribute to the ongoing discussions about LS waterflooding mechanism(s). For this purpose, a series of different experiments were conducted. At first, the effect of salinity on the interfacial tension (IFT) and the contact angle was evaluated with a crude oil sample. Then to achieve more accurate results in observing oil/water interface, similar IFT experiments were also carried out on a synthetic oil containing asphaltenes. Thereafter, microscopic... 

A new nonlinear adaptive impedance-based trilateral controller is proposed to ensure the absolute stability of multi-degrees-of-freedom (DOFs) dual-user haptic teleoperation systems subjected to communication delays. Using this strategy, reference impedance models are realized for the trilateral teleoperation system represented by a three-port network to facilitate cooperation of two human operators in order to perform a remote physical task. For this purpose, an impedance model defines the desired haptic interaction between the two human operators, while another impedance model specifies the desired behavior of the slave robot in terms of tracking the mater robots' trajectories during... 

In this paper, an approach to physical collaboration between a patient and a therapist is proposed using a bilateral impedance control strategy developed for delayed tele-robotic systems. The patient performs a tele-rehabilitation task in a resistive virtual environment with the help of online assistive forces from the therapist being provided through teleoperation. Using this strategy, the patient's involuntary hand tremors can be filtered out and the effort of severely impaired patients can be amplified in order to facilitate their early engagement in physical tasks. The response of the first desired impedance model is tracked by the master robot (interacting with the patient), and the... 

A nonlinear model reference adaptive bilateral impedance controller is proposed that can accommodate various cooperative tele-rehabilitation modes for patient–therapist interaction using a multi-DOF tele-robotic system. In this controller, two reference impedance models are implemented for the master and slave robots using new model reference adaptive control laws for the nonlinear bilateral teleoperation system. “Hand-over-hand” and “adjustable-flexibility” are two modes of patient–therapist cooperation that are realized using the proposed strategy. The Lyapunov-based stability proof guarantees the patient's and the therapist's safety during the cooperation and interaction with robots, even... 

A non-linear robust adaptive bilateral impedance controller is proposed to provide the absolute stability of multi-DOF teleoperation systems with communication delays, in addition to the force and position tracking performance. The proposed controller realises two desired (or reference) impedance models for the master and slave robots using a new non-linear robust version of the model reference adaptive control scheme. Using the absolute stability criterion, the robustness condition of the teleoperation system against communication delays is obtained, resulting in suitable adjustments of parameter values in the desired impedance models. In addition, using the Lyapunov stability theorem, the... 

A bilateral impedance controller is presented to enable robot-assisted surgery of a beating heart. For this purpose, two desired impedance models are designed and realized for the master and slave robots interacting with the operator (surgeon) and the environment (heart tissue), respectively. The impedance models are designed such that (a) the slave robot complies with the oscillatory motion of the beating heart and (b) the surgeon perceives the non-oscillatory portion of the slave/heart contact force at the master robot implying arrested-heart surgery. These performance goals are achieved via appropriate adjustment of the impedance model parameters without any measurement or estimation of... 

A novel impedance-controlled teleoperation system is developed for robot-assisted tele-echography of moving organs such as heart, chest and breast during their natural motions (beating and/or breathing). The procedure of devising the two impedance models for the master and slave robots is developed such that (a) the slave robot holding the ultrasound (US) probe follows the master trajectory but complies with the oscillatory interaction force of the moving organ, and (b) the sonographer receives feedback from the non-oscillatory portion of the slave-organ interaction force via the master robot similar to the haptic feedback received in echography of a stationary organ. These goals are... 

In this paper, a new impedance-based teleoperation strategy is proposed for assist-as-needed tele-rehabilitation via a multi-DOF telerobotic system having patient–master and therapist–slave interactions. Unlike a regular teleoperation system and as the main contribution of this work to minimize the therapist's movements, the therapist's hand only follows the patient's deviation from the target trajectory. Also it provides a better perception of the patient's problems in motor control to the therapist The admissible deviation of the patient's limb from a reference target trajectory is governed by an impedance model responding to both patient's and therapist's interaction forces. As the other... 

In this paper, a method for fast processing of data stream tuples in parallel execution of continuous queries over a multiprocessing environment is proposed. A copy of the query plan is assigned to each of processing units in the multiprocessing environment. Dynamic and continuous routing of input data stream tuples among the graph constructed by these copies (called the QueryMega Graph) for each input tuple determines that, after getting processed by each processing unit (e.g., processor), to which next processor it should be forwarded. Selection of the proper next processor is performed such that the destination processor imposes the minimum tuple latency to the corresponding tuple, among... 

Aside from the many services that soil provides, it also stores water and makes it available to crops, which is critical for food security. However, the necessity of further studies for overcoming the existing gap in relation to the role of soil in the water, energy, and food nexus system has been preoccupying the experts and specialists around the world for some time. In this sense, the balance between many key ecosystem components based on the Soil, water, energy, and food (SWEF) nexus framework is one of the key characteristics of holistic and accommodative watershed management systems. To the best of our knowledge, the watershed scale is used as a planning unit for the first time in the... 

Needle insertion simulation and planning systems (SPSs) will play an important role in diminishing inappropriate insertions into soft tissues and resultant complications. Difficulties in SPS development are due in large part to the computational requirements of the extensive calculations in finite element (FE) models of tissue. For clinical feasibility, the computational speed of SPSs must be improved. At the same time, a realistic model of tissue properties that reflects large and velocity-dependent deformations must be employed. The purpose of this study is to address the aforementioned difficulties by presenting a cost-effective SPS platform for needle insertions into the liver. The study... 

Ammonia detoxification is one of the main functions of the liver results in production of urea. In this study ammonia elimination and urea production was simulated in a microchannel mimicking the hepatic porto central axis. Navier- Stockes equations along with convection equations were solved for the related species in the entire domain. Since the Reynolds number was small (~1) the fluid flow regime was laminar. Urea cycle was modeled regarding its four main enzymes. Twelve rate equations were also solved in order to obtain the concentration of each metabolites participating in urea cycle. Concentration of the urea reached its maximum ca. 1.2e-5 M at the end of the channel which is in good... 

One important functionality of liver cells is ammonia detoxification and urea production. In this study, a numerical model of the urea cycle in hepatocytes was developed. Navier Stokes and convection equations were employed to study the process of ammonia elimination and urea production using a microfluidic channel. The concentration of urea and ammonia throughout the channel was obtained. Furthermore, the urea cycle was modelled with respect to its four main enzymes. This resulted in twelve rate equations that were solved to determine the concentration of each metabolite participating in the urea cycle. Application of results implied common disorders such as hyperammonemia types I and II... 

One important functionality of liver cells is ammonia detoxification and urea production. In this study, a numerical model of the urea cycle in hepatocytes was developed. Navier Stokes and convection equations were employed to study the process of ammonia elimination and urea production using a microfluidic channel. The concentration of urea and ammonia throughout the channel was obtained. Furthermore, the urea cycle was modelled with respect to its four main enzymes. This resulted in twelve rate equations that were solved to determine the concentration of each metabolite participating in the urea cycle. Application of results implied common disorders such as hyperammonemia types I and II... 

Waterflooding has been regarded as an efficient method for pressure maintenance of oil reservoirs. x Improved techniques such as Smart Water flooding as a new EOR/IOR process has gained more momentum based on the recent research activities in this field and the reduction of oil price. Despite many efforts on achieving the governing mechanisms of Smart Water flooding in many individual fields, most of data are sparse and more possible mechanisms which explains all the interactions yet to be introduced. This experimental study used a systematic laboratory framework which is based on seawater treatments at fixed ionic strength to eliminate the ionic strength effects, NaCl considered as the...