There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Antimicrobial activity of the metals and metal oxide nanoparticles

19세기말 애국적 담론과 新小說의 정체성

Infectious diseases remain one of the leading causes of morbidity and mortality worldwide. The WHO and CDC have expressed serious concern regarding the continued increase in the development of multidrug resistance among bacteria. Therefore, the antibiotic resistance crisis is one of the most pressing issues in global public health. Associated with the rise in antibiotic resistance is the lack of new antimicrobials. This has triggered initiatives worldwide to develop novel and more effective antimicrobial compounds as well as to develop novel delivery and targeting strategies. Bacteria have developed many ways by which they become resistant to antimicrobials. Among those are enzyme inactivation, decreased cell permeability, target protection, target overproduction, altered target site/enzyme, increased efflux due to over-expression of efflux pumps, among others. Other more complex phenotypes, such as biofilm formation and quorum sensing do not appear as a result of the exposure of bacteria to antibiotics although, it is known that biofilm formation can be induced by antibiotics. These phenotypes are related to tolerance to antibiotics in bacteria. Different strategies, such as the use of nanostructured materials, are being developed to overcome these and other types of resistance. Nanostructured materials can be used to convey antimicrobials, to assist in the delivery of novel drugs or ultimately, possess antimicrobial activity by themselves. Additionally, nanoparticles (e.g., metallic, organic, carbon nanotubes, etc.) may circumvent drug resistance mechanisms in bacteria and, associated with their antimicrobial potential, inhibit biofilm formation or other important processes. Other strategies, including the combined use of plant-based antimicrobials and nanoparticles to overcome toxicity issues, are also being investigated. Coupling nanoparticles and natural-based antimicrobials (or other repurposed compounds) to inhibit the activity of bacterial efflux pumps; formation of biofilms; interference of quorum sensing; and possibly plasmid curing, are just some of the strategies to combat multidrug resistant bacteria. However, the use of nanoparticles still presents a challenge to therapy and much more research is needed in order to overcome this. In this review, we will summarize the current research on nanoparticles and other nanomaterials and how these are or can be applied in the future to fight multidrug resistant bacteria.

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Nano-Strategies to Fight Multidrug Resistant Bacteria-"A Battle of the Titans".

Conventional polyolefins new polyolefins stereoregular polar thermoplastics syndiotactic polystyrene unplasticized polyvinyl chloride (uPVC) - fracture and fatigue properties acrylonitrile-butadiene-styrene (ABS) polymers styrene copolymers polyacrylonitrile polyacrylates polyacrylamides vinyl acetate polymers vinyl alcohol polymers synthetic water-soluble polymers cellulose plastics thermoplastic elastomers thermplastic polyurethanes polyester-based thermplastic elastomers polybutylene terephthalate compatibilized thermoplastic blends toughening of thermoplastics polyacetal polyether polyarylates polycarbonates polyamides polyimides polybenzimidazoles aromatic polyhydrazides and their corresponding polyoxadiazoles polyphenylquinoxalines polyphenylene sulfide polyphenylene vinylene conducting thermoplastics conducting thermoplastics composites poly(aryl ether sulfone)s poly(aryl ether ketone)s poly(aryl ether ketones-co-sulfones) poly(aryl ether ketone amide)s polytetrafluoroethylene liquid crystalline polymers advanced thermoplastics composites.

Handbook of Thermoplastics

In this study, the dielectric properties of PVA/ZnO nanocomposites films were evaluated. The composites were prepared by a solution casting technique. The dispersion and functionalization of the ZnO nanoparticles in the composite films were characterized by spectroscopic technique. The surface morphology of the PVA/ZnO nanocomposites films were elucidated using AFM. The charge transport properties were evaluated based on the dielectric and impedance spectroscopy techniques. Low ZnO loading composite shows low dielectric value at higher frequency and behaves as a lossless material. The complex impedance spectra suggest the change in conductivity, due to the change in bulk resistance of the materials and less relaxation time. Thus, all PVA/ZnO nanocomposites behave as lossless materials above 10(6) Hz indicating the composites are useful in microwave application. (c) 2012 Elsevier Ltd. All rights reserved.

Dielectric properties of novel PVA/ZnO hybrid nanocomposite films

The different investigation has been carried out on the biological activities of titanium dioxide nanoparticle but the effect of this nano product on the antibacterial activity of different antibiotics has not been yet demonstrated. In this study the nano size TiO2 is synthesized using citric acid and alpha dextrose and the enhancement effect of TiO2 nanoparticle on the antibacterial activity of different antibiotics was evaluated against Methicillin-resistant Staphylococcus aureus (MRSA). During the present study, different concentrations of nano-scale TiO2 were tested to find out the best concentration that can have the most effective antibacterial property against the MRSA culture. Disk diffusion method was used to determine the antibacterial activity of these antibiotics in the absence and presence of sub inhibitory concentration of TiO2 nano particle. A clinical isolate of MRSA, isolated from Intensive Care Unit (ICU) was used as test strain. In the presence of sub-inhibitory concentration of TiO2 nanoparticle (20 µg/disc) the antibacterial activities of all antibiotics have been increased against test strain with minimum 2 mm to maximum 10mm. The highest increase in inhibitory zone for MRSA was observed against pencillin G and amikacin (each 10 mm). Conversely, in case of nalidixic acid, TiO2 nanoparticle showed a Synergic effect on the antibacterial activity of this antibiotic against test strain. These results signify that the TiO2 nanoparticle potentate the antimicrobial action of beta lactums, cephalosporins, aminoglycosides, glycopeptides, macrolids and lincosamides, tetracycline a possible utilization of nano compound in combination effect against MRSA.

/pdf/effect-of-nano-titanium-dioxide-with-different-antibiotics-4t85h6k8up.pdf

Effect of Nano - Titanium Dioxide with Different Antibiotics against Methicillin-Resistant Staphylococcus Aureus

Preparation and characterization chemistry of nano-crystalline Ni–Cu–Zn ferrite

The Cadmium oxide doped in nanocrystalline polyaniline (CdO/PANI) composite were prepared with various weight percentages by in situ polymerization method using aniline, ammonium per sulfate, and CdO as starting materials. The frequency dependent conductivity and dielectric behavior of PANI/CdO composites have been studied. The formation of nano PANI and PANI/CdO composites with regards to the structural and microstructural properties of the materials were investigated by XRD, FTIR, and SEM techniques. The variation of σac with frequency obeys Jonscher power law except a small deviation in the low frequency region and is due to dipole polarization effect. The σac increases with increase in CdO concentration. Studies of dielectric properties at lower frequencies show that the relaxation behavior is superimposed by dipole polarization effect. The appearance of peak for each concentration in the loss tangent suggests the presence of relaxing dipoles in the PANI/CdO composite. On addition of CdO, the peak shifts toward higher frequency side indicating the speed up of the relaxation time. Analysis of frequency dependent dielectric suggests that the electronic and polymer segmental motions are strongly coupled. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Studies of AC conductivity and dielectric relaxation behavior of CdO-doped nanometric polyaniline

Poly(3,4-ethylenedioxythiophene); poly(styrenesulphonate) (PEDOT-PSS) is one of the most successful polymer for many of the electronic applications. It can be easily dispersed in water and few polar organic solvents. It is well known that the PEDOT-PSS dispersed in aqueous solution has very low conductivity which hinders its application as a transparent electronic material. In this paper we report the conductivity enhancement and dielectric parameters of PEDOT-PSS transparent films prepared using DMSO as an organic solvent. The structural properties of prepared films were investigated by SEM, UV–visible spectroscopy and FTIR spectroscopy. The SEM studies on these films indicate the formation of granular islands in the composite films. The FTIR spectra of DMSO in PEDOT-PSS indicate the shifting of characteristics peaks at higher wave number with the decrease in peak intensity in comparison to the pristine PEDOT-PSS. The UV–visible studies show the sharp absorptions around 500–700 nm at NIR range for the PEDOT-PSS doped with DMSO. It is observed that the addition of DMSO does the conformational change in the PEDOT-PSS from coil structure to linear structure. The change in morphology due to addition of DMSO brings feasibility in charge transportation through PEDOT backbone of polymer chain resulting in conductivity enhancement and low dielectric permeability and tangent loss in the composite thin films. It is observed that, the addition of DMSO increases the conductivity of pristine PEDOT-PSS by three orders of magnitude. Therefore, these DMSO doped PEDOT-PSS can be used in many optoelectronic applications as a transparent and flexible conducting polymer.

Aashis S. Roy

Papers

Dielectric properties of novel PVA/ZnO hybrid nanocomposite films

Effect of Nano - Titanium Dioxide with Different Antibiotics against Methicillin-Resistant Staphylococcus Aureus

Preparation and characterization chemistry of nano-crystalline Ni–Cu–Zn ferrite

Studies of AC conductivity and dielectric relaxation behavior of CdO-doped nanometric polyaniline

Conductivity and dielectric properties of PEDOT-PSS doped DMSO nano composite thin films