Dielectric properties and potential applications of alizarin yellow GG-Cu(II) complex film blended with polyvinyl alcohol

Bismuth ferrite (BFO), one of very few multiferroics with simultaneous coexistence of ferroelectric and magnetic ordering, has attracted much attention due to its potential applications for new memory devices. In this work, 30~90 nm BFO powders with single rhombohedral phase were prepared by chemical coprecipitation method and after calcining of 500oC. Photocatalytic properties of the powders and dielectric properties of BFO ceramic were characterized, respectively. Cut-off wavelength of the powders at 590 nm exhibited efficient ultraviolet photocatalytic activity, which has been demonstrated by a photocatalytic result. 0.3g BFO powders can make 10 ppm RhB aqueous solution (100 ml) to decolorize and RhB decomposition rate reached to 95% during 3 hr UV irradiation. BFO ceramic can be obtained by sintering the green disc compacted with BFO powders at 800oC for 1h. Its dielectric constant is t about 250, and its dielectric loss is 0.03 at below 100 oC in the frequency range of 102 ~ 104 Hz and up to 1200 at 200 oC under 1 kHz, respectively. Reduced polarization is found due to higher loss and lower dielectric constant of the ceramic when the measuing frequency is more than 104 Hz. Magnetic hysteresis loop of BFO ceramic also shows weaker magnetic property, which may be attributed to size confinement effect of the nanostructures.

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Polyvinyl alcohol/silica hybrid microspheres: synthesis, characterization and potential applications as adsorbents

Materials Research Express ◽

10.1088/2053-1591/aaffa7 ◽

2019 ◽

Vol 6 (5) ◽

pp. 055201

Author(s):

Shu-Hua Teng ◽

Niu Niu ◽

Feng-Wu Chen ◽

Peng Wang

Keyword(s):

Polyvinyl Alcohol ◽

Potential Applications ◽

Silica Hybrid

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Dynamic dielectric properties characterization of tapered dielectrophoresis microelectrodes for selective detection and rapid manipulation of cells

Microelectronics International ◽

10.1108/mi-03-2020-0015 ◽

2020 ◽

Vol 37 (4) ◽

pp. 189-198

Author(s):

Muhamad Ramdzan Buyong ◽

Farhad Larki ◽

Celine Elie Caille ◽

Norazreen Abd Aziz ◽

Ahamad Ghadafi Ismail ◽

...

Keyword(s):

Dielectric Properties ◽

Clear Correlation ◽

Selective Detection ◽

Blood Components ◽

Label Free ◽

Content Type ◽

Protein Toxin ◽

Polarization Factor ◽

Potential Applications

Purpose This paper aims to present the dielectrophoresis (DEP) force (FDEP), defined as microelectrofluidics mechanism capabilities in performing selective detection and rapid manipulation of blood components such as red blood cells (RBC) and platelets. The purpose of this investigation is to understand FDEP correlation to the variation of dynamic dielectric properties of cells under an applied voltage bias. Design/methodology/approach In this paper, tapered design DEP microelectrodes are used and explained. To perform the characterization and optimization by analysing the DEP polarization factor, the change in dynamic dielectric properties of blood components are observed according to the crossover frequency (fxo) and adjustment frequency (fadj) variation for selective detection and rapid manipulation. Findings Experimental observation of dynamic dielectric properties change shows clear correlation to DEP polarization factor when performing selective detection and rapid manipulation. These tapered DEP microelectrodes demonstrate an in situ DEP patterning efficiency more than 95%. Research limitations/implications The capabilities of tapered DEP microelectrode devices are introduced in this paper. However, they are not yet mature in medical research studies for various purposes such as identifying cells and bio-molecules for detection, isolation and manipulation application. This is because of biological property variations that require further DEP characterization and optimization. Practical implications The introduction of microelectrofluidics using DEP microelectrodes operate by selective detecting and rapid manipulating via lateral and vertical forces. This can be implemented on precision health-care development for lab-on-a-chip application in microfluidic diagnostic and prognostic devices. Originality/value This study introduces a new concept to understand the dynamic dielectric properties change. This is useful for rapid, label free and precise methods to conduct selective detection and rapid manipulation of mixtures of RBC and platelets. Further, potential applications that can be considered are for protein, toxin, cancer cell and bacteria detections and manipulation. Implementation of tapered DEP microelectrodes can be used based on the understanding of dynamic dielectric properties of polarization factor analysis.

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Evaluation of Polyvinyl Alcohol/Cobalt Substituted Hydroxyapatite Nanocomposite as a Potential Wound Dressing for Diabetic Foot Ulcers

International Journal of Molecular Sciences ◽

10.3390/ijms21228831 ◽

2020 ◽

Vol 21 (22) ◽

pp. 8831

Author(s):

Wei-Chun Lin ◽

Cheng-Ming Tang

Keyword(s):

Polyvinyl Alcohol ◽

Diabetic Foot ◽

Wound Dressing ◽

Foot Ulcers ◽

Diabetic Foot Ulcers ◽

E Coli ◽

Accelerate Wound Healing ◽

Persistent Infections ◽

Electrochemically Deposited ◽

Potential Applications

Diabetic foot ulcers (DFUs) caused by diabetes are prone to serious and persistent infections. If not treated properly, it will cause tissue necrosis or septicemia due to peripheral blood vessel embolism. Therefore, it is an urgent challenge to accelerate wound healing and reduce the risk of bacterial infection in patients. In clinical practice, DFUs mostly use hydrogel dressing to cover the surface of the affected area as an auxiliary treatment. Polyvinyl alcohol (PVA) is a hydrophilic hydrogel polymer widely used in dressings, drug delivery, and medical applications. However, due to its weak bioactivity and antibacterial ability, leads to limited application. Filler adding is a useful way to enhance the biocompatibility of PVA. In our study, cobalt-substituted hydroxyapatite (CoHA) powder was prepared by the electrochemically-deposited method. PVA and PVA-CoHA nanocomposite were prepared by the solvent casting method. The bioactivity of the PVA and composite was evaluated by immersed in simulated body fluid for 7 days. In addition, L929 cells and E. coli were used to evaluate the cytotoxicity and antibacterial tests of PVA and PVA-CoHA nanocomposite. The results show that the addition of CoHA increases the mechanical properties and biological activity of PVA. Biocompatibility evaluation showed no significant cytotoxicity of PVA-CoHA composite. In addition, a small amount of cobalt ion was released to the culture medium from the nanocomposite in the cell culture period and enhanced cell growth. The addition of CoHA also confirmed that it could inhibit the growth of E. coli. PVA-CoHA composite may have potential applications in diabetic trauma healing and wound dressing.

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