Designing biocompatible Ti-based metallic glasses for implant applications

Ti-based metallic glasses show high potential for implant applications; they overcome in several crucial respects their well-established biocompatible crystalline counterparts, e.g. improved corrosion properties, higher fracture strength and wear resistance, increased elastic strain range and lower Young's modulus. However, some of the elements required for glass formation (e.g. Cu, Ni) are harmful for the human body. We critically reviewed the biological safety and glass forming tendency in Ti of 27 elements. This can be used as a basis for the future designing of novel amorphous Ti-based implant alloys entirely free of harmful additions. In this paper, two first alloys were developed: Ti₇₅Zr₁₀Si₁₅ and Ti₆₀Nb₁₅Zr₁₀Si₁₅. The overheating temperature of the melt before casting can be used as the controlling parameter to produce fully amorphous materials or bcc-Ti-phase reinforced metallic glass nano-composites. The beneficial effect of Nb addition on the glass-formation and amorphous phase stability was assessed by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. Crystallization and mechanical behavior of ribbons are influenced by the amount and distribution of the nano-scaled bcc phase existing in the as-cast state. Their electrochemical stability in Ringer's solution at 310 K was found to be significantly better than that of commercial Ti-based biomaterials; no indication for pitting corrosion was recorded.     

Effects of Pb-Doping on Phase Structural and Optical Properties of CdZnS Nano-Powders

Cadmium zinc lead sulfide[Cd0.8(Zn1-x,Pbx)0.2S] nano-powders were prepared by an improved coprecipitation method. The effect of Pb2+ concentration at 500℃ on the phase and crystalline structure of the Cd0.8(Zn1-x,Pbx)0.2S powders were investigated by X-ray diffraction (XRD). According to the transmission electron microscopy (TEM) images, the particles size are in the range of 58 nm to 72 nm. In addition, optical band gap energy and optical constants of nano-powders were determined using the ultraviolet (UV) spectrum, Fournier transform infrared spectroscopy (FTIR), and Kramers-Kronig analysis, respectively. We calculate the refractive index n, extinction coefficient k, and dielectric function as a function of the wavenumber. The experiment results demonstrate that the amount of Pb+2 has been playing an increasingly important role on optical properties of CZPS nanocrystals.     

Application of graphite screen printed electrode modified with dysprosium tungstate nanoparticles in voltammetric determination of epinephrine in the presence of acetylcholine

The current work focuses on the development of a sensitive and selective electrochemical device based on a graphite screen printed electrode modified with Dy_2(WO_4)_3 nanoparticles(DWO/SPE) for the analysis of epinephrine in samples also containing acetylcholine. The study proves that the sensor has excellent electron-mediating behavior in the oxidation of epinephrine in a 0.1 mol/L phosphate buffer solution(PBS)(pH 7.0). The application of the DWO/SPE in differential pulse voltammetry(DPV) is found to lead to distinct response for the oxidation of epinephrine and acetylcholine, with the potentials of the epinephrine and acetylcholine peaks(△E_p) to be 550 mV apart. The detection limits of the method for epinephrine and acetylcholine are 0.5 and 0.7 μmol/L(S/N = 3) and the responses are found to be linear in the concentration ranges of 1.0-900.0 μmol/L and 1.0-1200.0 μmol/L in a PBS buffer(pH = 7.0)respectively. The modified electrode was used for the detection of epinephrine and acetylcholine in real samples and found to produce satisfactory results. These results can be a proof that Dy_2(WO_4)_3 nanoparticles can find promising applications in electrochemical sensors to be used for the analysis of(bio)chemical species.     

Nigella sativa L. improves lipid profile and prevents atherosclerosis: Evidence from an experimental study on hypercholesterolemic rabbits

The effects of Nigella sativa (NS) on lipid profile, C-reactive protein, oxidized LDL, antioxidant capacity, Apo A and Apo B and fatty streak formation in hypercholesterolemic male rabbits were examined. Fifteen rabbits were distributed into three groups of five each [normal diet, hypercholesterolemic diet (1% cholesterol) and hypercholesterolemic diet (1% cholesterol) supplemented with 5% NS]. They received rabbit laboratory chow diet for a period of 8 weeks. At the start and end of the study, fasting blood was taken from all animals. NS significantly decreased fatty streak formation as well as total cholesterol (TC) and low-density lipoprotein (LDL) in hypercholesterolemic male rabbits. NS showed positive effects on other factors (triacylglycerol, high-density lipoprotein, C-reactive protein, oxidized LDL, antioxidant capacity, Apo A and Apo B), but these were insignificant. Based on favorable efficiency of NS on TC and LDL reduction and its anti-atherogenic cardioprotective properties, it is suggested using this plant with fat-rich diets simultaneously may reduce their adverse health effects.     

Robust controllability and observability degrees of polynomially uncertain systems

This paper deals with the class of polynomially uncertain continuous-time linear time-invariant (LTI) systems whose uncertainties belong to a semi-algebraic set. The objective is to determine the minimum of the smallest singular value of the controllability or observability Gramian over the uncertainty region. This provides a quantitative measure for the robust controllability or observability degree of the system. To this end, it is shown that the problem can be recast as a sum-of-squares (SOS) problem. In the special case when the uncertainty region is polytopic, the corresponding SOS formulation can be simplified significantly. One can apply the proposed method to any large-scale interconnected system in order to identify those inputs and outputs that are more effective in controlling the system, in a robust manner. This enables the designer to simplify the control structure by ignoring those inputs and outputs whose contribution to the overall control operation is relatively weak. A numerical example is presented to demonstrate the efficacy of the results.     

Transactive energy management for optimal scheduling of interconnected microgrids with hydrogen energy storage

In recent years, renewable energy sources (RESs) have attracted substantial attention due to carbon-free and cost-effective advantages that have made them one of the main sources of energy generation in the modern structure of the power grid. This paper proposes the stochastic day-ahead scheduling model for optimal energy management of renewable-based microgrids. In this paper, each microgrid is equipped with 100% RESs including the PV system and wind turbine for full pollutant-free energy generation while the hydrogen energy storage (HES) system is used for alleviating the intermittences of the RESs aiming to dynamically balance the energy during a day. To model the fluctuations such as day-ahead market price in the microgrids, the autoregressive integrated moving average and fast forward selection methods are exerted for scenario production and reduction, respectively. Transactive energy as a sustainable and reliable technique is considered for controlling and coordinating energy sharing among the microgrids and the energy network for dynamic energy balancing in the deregulated environment. For energy management in the demand-side, the price and load response schemes are presented, aiming to revise the consumers' patterns in energy consumption in line with balancing energy and minimizing the microgrids’ energy cost. The effectiveness of the suggested model is validated using the modified IEEE 24-bus case study. The realistic modeling of the system based on the proposed model has led to an 8.51% increment in energy cost.     

Bioassay Development for Bispecific Antibodies—Challenges and Opportunities

Antibody therapeutics are expanding with promising clinical outcomes, and diverse formats of antibodies are further developed and available for patients of the most challenging disease areas. Bispecific antibodies (BsAbs) have several significant advantages over monospecific antibodies by engaging two antigen targets. Due to the complicated mechanism of action, diverse structural variations, and dual-target binding, developing bioassays and other types of assays to characterize BsAbs is challenging. Developing bioassays for BsAbs requires a good understanding of the mechanism of action of the molecule, principles and applications of different bioanalytical methods, and phase-appropriate considerations per regulatory guidelines. Here, we review recent advances and case studies to provide strategies and insights for bioassay development for different types of bispecific molecules.     

Multi-Objective Hydraulic Optimization of Diversion Dam’s Cut-Off

The seepage flow beneath a hydraulic structure is formed by the hydraulic head difference between the upstream and downstream sides. Cut-off walls are often applied, as an expedience, to reduce the seepage flow through the foundation of diversion dams and to enhance the efficiency of these dams. In this research, perhaps for the first time, a novel methodology is propounded to assess the optimum characteristics of cut-off walls in diversion dams in order to ameliorate hydraulic interactions between the diversion dam foundation and the cut-off walls behavior, also their construction cost is minimized. The results are used to train and validate the Multi-Layer Perceptron (MLP) simulation model. Then MLP, as a meta-model for simulation of the hydraulic behavior of cut-off walls, is coupled with a robust multi-objective optimization algorithm, Non-dominated Sorting Genetic Algorithm-ΙΙ (NSGA-ΙΙ), to create a trade-off between the intended goals. Finally, Preference Ranking Organization METHod for Enrichment Evaluation (PROMETHEE) decision making model and Nash-Harsanyi bargaining model are utilized to find the compromise design optimal solution on the trade-off curve. Results demonstrate that the best agreed-upon design optimal solution using PROMETHEE and Nash-Harsanyi bargaining models can be considered as (10, 3.84, 32) meters and (2.47, 10, 29.22) meters for optimum depth of the upstream and downstream cut-off walls and the optimum distance between them, respectively.