Gold nanoparticles from magnetite for the detection of amyloid proteins in neurodegenerative diseases

Introduction. Currently, neurodegenerative diseases (ND) are the fourth leading cause of death worldwide that pose a great challenge in the development of tools for early diagnosis. Thus, advances in science seek sensitive and selective detection systems and this manuscript will highlight the importance of nanotechnology. Material and methods. A literature review was conducted on the representative findings of NPs technologies in neurodegenerative diseases. Articles written in both English and Spanish were included. References between 2015-2021 were also taken into account. Results. One of the most representative techniques, AuNP was specifically implemented, together with a magnetic center composed of magnetite, which has as a specific ligand with a C-terminal cysteine domain present in the B-amyloid protein, which adhere directly to the surface of the NPs, characterizing the anomalous protein. Subsequently, by means of nanosensors capable of detecting and measuring different concentrations, these pathologies are identified at an early stage. Conclusions. Today, along with the advent of biotechnology, it has been possible to design techniques with NPs that allow the identification of specific mutations and provide diagnosis in individuals. In the investigative models of AuNP, it is possible to infer that the capabilities that make them representative focus on their magnetism and biofunctionality, by specifically binding to amyloid peptides and other ligands present in the protein, which are the major components of amyloid plaques used in these studies.

Preparation of Fe3O4@SiO2–ZnO catalyst and its catalytic synthesis of rosin glycol ester

In order to solve the problems of low recovery, low availability, and high cost in the synthesis of rosin glycol ester, a series of supported ZnO magnetic catalysts were prepared with Fe3O4 as the magnetic center, and their structures and compositions were characterized by TEM, XRD, and XPS. Through screening, the results show that Fe3O4@SiO2–ZnO has the best catalytic effect, far better than other catalysts, and has good stability. At the same time, the effects of zinc source and its load and different reaction conditions on the synthesis of rosin glycol ester were also investigated. The results showed that: When zinc chloride was used as zinc source, theoretical loading of zinc source was 0.45 g, reaction temperature was 270°C, reaction time was 5 h, and catalyst dosage was 0.2 g, the esterification rate of rosin-glyceryl ester was 87.2% and acid value was 26.5 mg KOH g−1.

Stiffness Measurement of Permanent Magnet Biased Radial Magnetic Bearing in MSFW

To measure current stiffness and displacement stiffness of permanent magnet biased radial magnetic bearing, a new stiffness measurement method is proposed for magnetically suspended flywheel (MSFW). The detailed stiffness measurement method is proposed in this paper. At first, the suspension force and stiffness characteristics of the permanent magnet biased radial magnetic bearing are studied using magnetic circuit method and finite element method (FEM). Second, the detailed stiffness measurement method of permanent magnet biased radial magnetic bearing is proposed. It has two procedures, one is the determination of the magnetic center in radial magnetic bearing when the gravity of rotor is in the +x(+y) direction and −x(−y) direction, respectively, then the current stiffness can be obtained, and the other is the calculation of the displacement stiffness according to the relationship between rotor displacement and current. A prototyped MSFW with angular moments of 50 Nms is manufactured, and the proposed stiffness measurement method of permanent magnet biased radial magnetic bearing is verified by prototyped experiments.

Reducing Energy Consumption in Active Magnetic Bearings by a Nonlinear Variable Bias Controller

This paper presents a nonlinear variable bias controller for an active magnetic bearing (AMB). The nonlinear bearing force is analyzed theoretically and the control current for various bias current settings is derived from the nonlinear bearing equation. Then the power consumption is minimized to obtain the optimum bias current expression analytically. Results show that the optimum bias current can be calculated from the demand bearing force and the instantaneous rotor displacement. Moreover, the influences of magnetic bearing parameter errors are investigated and correction methods are introduced. Results of experimental rotational tests show that the rotor dynamics are not altered under variable bias currents if the proposed correction for parameter errors is implemented. The magnetic center of misalignment is also detected and compensated for. The proposed variable bias current controller provides not only significant energy savings, but also it is simple to implement and applicable to wide range of magnetic bearing systems without deterioration of the bearing dynamics.

A Study on Mathematical Modeling Technology for Magnetic-Fluid Grinding

The paper introduces the precision processing technology of grinding using magnetic fluid and presents the working mechanism of magnetic-fluid grinding. Based on Preston Equation, it also establishes a mathematical modeling for magnetic-fluid grinding, which is used to study the relationships between the effects of grinding and the variation of such technological parameters as the revolving speed of work-piece, the intensity of magnetic field, the distance between work-piece surface and magnetic center, the size of the magnetic fluid and grinding time, etc. Analysis on the grinding of Si3N4 ceramic-balls proves that the model has been well established.