Synthesis and characterization of insulin/zirconium phosphate@TiO2 hybrid composites for enhanced oral insulin delivery applications

Abstract

In this work, a series of composites of insulin (Ins)/zirconium phosphate (ZrP) were synthesized by intercalation method, then, these composites were coated with TiO₂ by sol-gel method to prepare Ins/ZrP@TiO₂ hybrid composites and the drug release of the composites was investigated by using UV-Vis spectroscopy. Ins/ZrP (10, 30, 60?wt%) composites were prepared by intercalation of insulin into the ZrP layers in water. Then Ins/ZrP composites were coated with different amounts of TiO₂ (30, 50, 100?wt %) by using titanium tetra n-butoxide, as precursor. Formation of intercalated Ins/ZrP and Ins/ZrP@TiO₂ hybrid composites was characterized by FT-IR, FE-SEM, BET and XRD analysis. Zeta potential of the optimized Ins/ZrP@TiO₂ hybrid composite was determined ?27.2?mV. Cytotoxic effects of the optimized Ins/ZrP@TiO₂ hybrid composite against HeLa and Hek293T cell lines were evaluated using MTT assay and the results showed that designed drug delivery system was not toxic in biological environment. Compared to the Ins/ZrP composites, incorporation of TiO₂ coating enhanced the drug entrapment considerably, and reduced the drug release. The Ins/ZrP composites without TiO₂ coating released the whole drug after 30?min in pH 7.4 (phosphate buffer solution) while the TiO₂-coated composites released the entrapped drug after 20?h. In addition to increasing the shelf life of hormone, this nanoencapsulation and nanocoating method can convert the insulin utilization from injection to oral and present a painless and more comfortable treatment for diabetics.     

Detection of cracks in refractory materials by an enhanced digital image correlation technique

This paper is devoted to the study of the fracture behaviour of two industrial refractory materials thanks to the development of a new technique of digital image correlation (DIC). DIC, already known as a helpful and effective tool for the measurement of displacement and deformation fields in materials, has been adapted to take into account displacement discontinuities as cracks. The material transformation, usually assumed homogeneous inside each DIC subset, is thus more complex, while each subset can be cut in two parts with different kinematics. By this way, it is possible to automatically find the fracture paths and follow the crack geometries (length, opening) during the loading with a higher spatial resolution than the one obtained by standard DIC. After having presented the principle of the new technique, its metrological performances are assessed from synthetic images and the choice of crack detection criterion is discussed. The capacity of this new technique is shown through a comparative study with standard DIC. Its application is led on magnesia-spinel refractory materials, specifically to highlight and to characterize the evolution of kinematic fields (displacement and strain) observed at the surface of sample during a wedge splitting test typically used to quantify the work of fracture. We show that refractories with aggregates of iron aluminate spinel present a fracture mechanism with crack branching and can dissipate more energy thanks to a longer crack network.     

Template free synthesis of natural carbohydrates functionalised fluorescent silver nanoclusters

Template‐assisted synthesis is one of the most recognised techniques for fabrication of silver nanoclusters (AgNCs). However, this process is time consuming, toxic and expensive. In this study, the authors report a completely novel approach for the green and facile synthesis of AgNCs using Matricaria chamomilla, without any additional template. Fluorescent and colloidally stable AgNCs with average particle size of 2.4 nm were successfully produced. They found that carbohydrates from Matricaria chamomilla act as an ideal template to generate fluorescent AgNCs. Moreover, oxygen‐bearing functional groups were validated to be the active groups for anchoring and reducing of Ag⁺ ions. The novel carbohydrate coating method makes the prepared nanoclusters completely hydrophilic and stable in aqueous matrices.Inspec keywords: silver, nanofabrication, toxicology, particle size, nanomedicineOther keywords: template free synthesis, natural carbohydrates functionalised fluorescent silver nanoclusters, template‐assisted synthesis, silver nanocluster fabrication, AgNC facile synthesis, Matricaria chamomilla, fluorescent AgNC, oxygen‐bearing functional groups, Ag⁺ ions, hydrophilic nanoclusters, aqueous matrices, size 2.4 nm, Ag     

Quarter car active suspension system: Minimum time controller design using singular perturbation method

Suspension systems have been widely applied to vehicles. Every vehicle moving on the randomly profiled road is exposed to vibration and shocks which is harmful both for the passengers in terms of comfort and for the durability of the vehicle itself. From this point of view, it is important to reset to zero displacement, velocity and acceleration of car in minimum time. So, this paper proposes a new minimum time controller based on bang-bang control for the quarter car active suspension systems. First by using singular perturbation method the original suspension system is decomposed into two fast and slow singular subsystems in theory, and then by Pontryagain’s Minimum Principle (PMP) and switching functions, the controller is designed for each subsystem and finally the optimal final time is obtained as maximum optimal time concluded of two subsystems. By using a degree of stability technique with two parameters (instead of four parameters), the optimal time is more reduced and leads to great simplifications in practical implementation. The performance of the controller is compared with the Sub optimal Linear Quadratic Regulator (SLQR) controller using two types of road profiles (step and bump) implemented in MATLAB/Simulink. Test results demonstrate the proposed controller is very more effective and simpler in eliminating fluctuations in suspension systems that finally provide the passengers comfort.     

Visual tracking based on adaptive interacting multiple model particle filter by fusing multiples cues

In visual tracking topic, developing a robust tracking method is very challenging, seen that there are many issues to look at, particularly, fast motion, target appearance changing, background clutter and camera motion. To override these problems, we present a new object tracking method with the fusion of interacting multiple models (IMM) and the particle filter (PF). First, the IMM is applied with a bank of parallel H∞ filter to estimate the global motion, the target motion is efficiently represented using only two parametric single models, and an adaptive strategy is preformed to adjust automatically the parameters of the two sub models at each recursive time step. Second, the particle filter is performed to estimate the local motion, we fuse the color and texture features to describe the appearance of the tracked object, we use the alpha Gaussian mixture model (α-GMM) to model the color feature distribution, the parameter α allows the probability function to possesses a flatter distribution, and the texture feature is represented by the distinctive uniform local binary pattern histogram (DULBP) based on the uniform local binary pattern (ULBP) operator; we fuse then the two features to represent the target’s appearance under the particle filter framework. We conduct quantitative and qualitative experiments on a variety of challenging public sequences; the results show that our method performs robustly and demonstrates strong accuracy.     

Robust Model-Free Control Applied to a Quadrotor UAV

The objective of this paper is to deal with a new technique based on Model-Free Control (MFC). The concept of this controller is to use a basic controller along with an ultra-local model to compensate for system’s uncertainties and disturbances. In this paper, a proposed algorithm is introduced based on an integrated structure between the Nonlinear Integral-Backstepping technique (NIB) and the MFC. The LQR, NIB, LQR-MFC, and NIB-MFC are implemented on a real quadrotor UAV. Various real-time flight tests are conducted to validate the importance of using the MFC side by side with NIB. The proposed combination shows robust performance compared to the other algorithms under fault-free and actuator fault conditions.     

Patch-based offline signature verification using one-class hierarchical deep learning

International Journal on Document Analysis and Recognition (IJDAR) - Automatic processing of offline signature verification (in general) can be considered as a low-cost solution to problems in...     

Predictive direct torque control with reduced ripples for induction motor drive based on T‐S fuzzy speed controller

Finite‐state model predictive control (FS‐MPC) has been widely used for controlling power converters and electric drives. Predictive torque control strategy (PTC) evaluates flux and torque in a cost function to generate an optimal inverter switching state in a sampling period. However, the existing PTC method relies on a traditional proportional‐integral (PI) controller in the external loop for speed regulation. Consequently, the torque reference may not be generated properly, especially when a sudden variation of load or inertia takes place. This paper proposes an enhanced predictive torque control scheme. A Takagi‐Sugeno fuzzy logic controller replaces PI in the external loop for speed regulation. Besides, the proposed controller generates a proper torque reference since it plays an important role in cost function design. This improvement ensures accurate tracking and robust control against different uncertainties. The effectiveness of the presented algorithms is investigated by simulation and experimental validation using MATLAB/Simulink with dSpace 1104 real‐time interface.     

Exploring ligand recognition and ion flow in comparative models of the human GABA type A receptor

We present two comparative models of the GABA(A) receptor. Model 1 is based on the 4-A resolution structure of the nicotinic acetylcholine receptor from Torpedo marmorata and represents the unliganded receptor. Two agonists, GABA and muscimol, two benzodiazepines, flunitrazepam and alprazolam, together with the general anaesthetic halothane, have been docked to this model. The ion flow is also explored in model 1 by evaluating the interaction energy of a chloride ion as it traverses the extracellular, transmembrane and intracellular domains of the protein. Model 2 differs from model 1 only in the extracellular domain and represents the liganded receptor. Comparison between the two models not only allows us to explore commonalities and differences with comparative models of the nicotinic acetylcholine receptor, but also suggests possible protein sub-domain interactions with the GABA(A) receptor not previously addressed.     

Inhibition of Steel Corrosion in Nitric Acid by Sulfur Containing Compounds

The inhibitive mechanism, thermodynamics, and adsorptive properties of thiobarbituric acid (TBA) and thiourea (TU) on the corrosion of mild steel in 0.5 M HNO₃ solution have been investigated using potentiodynamic, electrochemical impedance spectroscopy techniques, and quantum chemical calculations. Both inhibitors showed good inhibition efficiency in nitric acid solution. TU was the most effective inhibitor and its inhibition efficiency increases with increasing concentration to attain 99% at 6 × 10^?3 mol · L^?1 at 30°C. Theoretical fitting of different isotherms, Langmuir, Flory–Huggins, Temkin, and the kinetic-thermodynamic models were tested to clarify the nature of inhibitors adsorption on mild steel surface. The obtained experimental data fitted all the applied adsorption isotherms except Langmuir. The thermodynamic activation parameters were determined to provide evidence of the inhibitory effect of TBA and TU. To determine the surface charge at the steel surface in nitric acid solution the potential of zero charge was measured using AC measurements at different potentials. Quantum chemical parameters were calculated and explained. The data clarified that the inhibition of steel in nitric acid by TU or TBA takes place through physicochemical adsorption mechanism.