Dynamic Response of Polyindole Coated Zinc Ferrite Particle Suspension under an Electric Field

ZnFe2O4 particles initially synthesized through a simple solvothermal method were coated using polyindole (PIn) to prepare an actively controllable core-shell typed hybrid material under both electric and magnetic fields. An advantage of this process is not needing to add the stabilizers or surfactants commonly used for uniform coating when synthesizing core or shell-structured particles. The synthesized ZnFe2O4/PIn particles have a lower density than conventional magnetic particles and have suitable properties as electrorheological (ER) particles. The expected spherical shape of the particles was proven using both scanning electron microscopy and transmission electron microscopy. The chemical characterization was performed using Fourier-transform infrared spectroscopy and X-ray diffraction analysis. To analyze the rheological properties, a ZnFe2O4/PIn based suspension was prepared, and dynamic rheological measurements were performed for different electric field strengths using a rotary rheometer. Both dynamic and elastic yield stresses of the ER fluid had a slope of 1.5, corresponding to the conductivity model. Excellent ER effect was confirmed through rheological analysis, and the prepared ER fluid had a reversible and immediate response to repeated electric fields.

Strong Electrorheological Performance of Smart Fluids Based on TiO2 Particles at Relatively Low Electric Field

Electrorheological (ER) fluids are a type of smart material with adjustable rheological properties. Generally, the high yield stress (>100 kPa) requires high electric field strength (>4 kV/mm). Herein, the TiO2 nanoparticles were synthesized via the sol–gel method. Interestingly, the ER fluid-based TiO2 nanoparticles give superior high yield stress of 144.0 kPa at only 2.5 kV/mm. By exploring the characteristic structure and dielectric property of TiO2 nanoparticles and ER fluid, the surface polar molecules on samples were assumed to play a crucial role for their giant electrorheological effect, while interfacial polarization was assumed to be dominated and induces large yield stress at the low electric field, which gives the advantage in low power consumption, sufficient shear stress, low leaking current, and security.

Magnetite/Poly(ortho-anisidine) Composite Particles and Their Electrorheological Response

Magnetic and semiconducting Fe3O4/poly(o-anisidine) (POA) core/shell composite particles were fabricated by an oxidation process using Fe3O4 synthesized separately. The dispersion stability in a liquid medium and the electrical conductivity of synthesized particles were improved because of the conductive POA polymeric shell. The morphological, microstructural, compositional/elemental, and thermal behaviors of the particles were characterized using SEM with energy dispersive X-ray spectroscopy, TEM, XRD, and thermogravimetric analysis, respectively. A smart electro-magneto-rheological suspension containing Fe3O4/POA particles with two functionalities, magnetism and conductivity, was prepared. Its electrorheological properties were investigated at different electric field strengths using a rotational rheometer. Without an electric field, the sample demonstrated typical Newtonian fluid behavior, as expected. However, while under the electric field, it exhibited a solid-like behavior, and the dynamic (or elastic) yield stress of the ER fluid increased linearly as a function of the electric field strength in a power-law function with an index of 2.0, following the polarization mechanism.

Synthesis and Electrorheological Response of Graphene Oxide/Polydiphenylamine Microsheet Composite Particles

Conducting graphene oxide/polydiphenylamine (GO/PDPA) microsheet nanocomposite particles were fabricated via in-situ oxidative polymerization using diphenylamine in the presence of GO. The morphological structures and dimensions of the fabricated GO/PDPA composites were evaluated using transmission electron microscopy and scanning electron microscopy. Electrorheological (ER) responses and creep behaviors of an ER fluid consisting of the GO/PDPA composites when suspended in silicone oil were evaluated using a rotational rheometer under input electric field. Three different types of yield stresses were examined along with dielectric analysis, demonstrating their actively tunable ER behaviors.

PROFILE OF DECREASED CONSCIOUSNESS IN GERIATRIC PATIENTS AT H. ADAM MALIK HOSPITAL MEDAN IN 2018

Introduction: The decline in consciousness, disruption of either the level or content of consciousness, is a significant problem in the ER (Emergency Room). The incidence varies from 4% to 10%. It is an emergency medical condition that requires proper evaluation and initial management in the ER. Fluid and electrolyte imbalance disorders leading to loss of consciousness among hospitalized geriatric patients and the infection and effects of the drug. Delirium is closely related to dehydration, a multifactorial problem associated with some physiological changes in old age. Aim: This research aims to know about the decline profile of consciousness in geriatric patients in RSUP H. Adam Malik Medan in the year 2018. Methods: This descriptive-analytic study used retrospective design by collecting the medical record data of the patients who had been consul to the geriatric division in 2018. There are 1391 research subjects taken in total sampling. Data analysis is presented in the form of the frequency distribution of respondents characteristics including age, gender, primary diagnosis of loss of consciousness, electrolyte examination, and head of CT-scans and analysis by using the Kruskall-Wallis test to determine the relationship age with the incidence of loss of consciousness due to electrolyte imbalance. Data analysis using SPSS 20th. Result: Obtained by the most five diseases that cause a loss of consciousness in geriatric patients, i.e., electrolyte imbalance (imbalance) 876 people (63.0%), ischemic stroke 155 people (11.1%), sepsis as many as 141 (10.1%), hemorrhagic stroke 89 people (6.4%), and hypoglycemia 69 (5.0%). Geriatric patients with electrolytes imbalance due to hyponatremia (89.3%) and hypokalemia(28.53%). There is no association between the age and the electrolyte levels of geriatric patients, p>0.05. Conclusion: Decreased consciousness in geriatric patients is most due to electrolyte imbalance.

Microfibrillated Cellulose Suspension and Its Electrorheology

Microfibrillated cellulose (MFC) particles were synthesized by a low-pressure alkaline delignification process, and their shape and chemical structure were investigated by SEM and Fourier transformation infrared spectroscopy, respectively. As a novel electrorheological (ER) material, the MFC particulate sample was suspended in insulating oil to fabricate an ER fluid. Its rheological properties—steady shear stress, shear viscosity, yield stress, and dynamic moduli—under electric field strength were characterized by a rotational rheometer. The MFC-based ER fluid demonstrated typical ER characteristics, in which the shear stresses followed the Cho–Choi–Jhon model well under electric field strength. In addition, the solid-like behavior of the ER fluid was investigated with the Schwarzl equation. The elevated value of both dynamic and elastic yield stresses at applied electric field strengths was well described using a power law model (~E1.5). The reversible and quick response of the ER fluid was also illustrated through the on–off test.

Significant enhancement of the electrorheological effect by non-straight electrode geometry

In contrast to the commonly used straight electrodes with electrorheological (ER) fluid, here we studied the effect of non-straight electrodes where more than one order of magnitude enhancement of the apparent viscosity was observed.