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Pooja Maharjan,Minki Jin,Daseul Kim,JaeWook Yang,Anjila Maharjan,Meong Cheol Shin,Kwan Hyung Cho,김만수,Kyoung Ah Min 대한약학회 2019 Archives of Pharmacal Research Vol.42 No.10
Ocular drug delivery has been a well-knownroute for the drug administration for the treatment of oculardiseases. However, numerous anatomical and physiologicalbarriers prevailing in the eye itself create considerablechallenges for achieving the necessitated therapeutic efficacyalong with ocular bioavailability. However, recentadvances in nanoengineered strategies hold definite promisesin terms of devising improved ophthalmic medicinesfor the effective drug delivery to target the sites withenhanced ocular bioavailability. Curcumin, a hydrophobicpolyphenol yellow colored compound, and its metabolicreduced product, tetrahydrocurcumin (THC), have beenknown for their beneficial pharmacological functions, suchas anti-inflammatory or anti-oxidant activities at varioustissue sites. However, the low aqueous solubility of thesecompounds results in their poor bioavailability, therebylimiting their widespread application. Therefore, in thepresent study, we investigated the changes in drug solubilityby forming inclusion complexes with differentderivatives of hydroxypropyl (HP)-cyclodextrins (CD). To this end, the spray drying technique was used for nanoengineeringcurcumin or THC-loaded formulations toimprove the stability of formulations during the storage. The formulations were characterized in terms of physicochemicalproperties and cellular permeability. The resultsdemonstrated that the encapsulation of curcumin (or THC)into the HP-CDs significantly increased the drug solubilityand enhanced the corneal and retinal epithelial permeability. Curcumin or THC complexes in HP-CDs withimproved bioavailability also induced anti-oxidant activity(SOD1, CAT1, and HMOX1) in higher levels in the ocularepithelial cells and showed oxidative protection effects inrabbit cornea tissues that will boost up their application inocular medicine.
Metabolic engineering of Nocardia sp. CS682 for enhanced production of nargenicin A1.
Maharjan, Sushila,Koju, Dinesh,Lee, Hei Chan,Yoo, Jin Cheol,Sohng, Jae Kyung Humana Press 2012 Applied biochemistry and biotechnology Vol.166 No.3
<P>A number of secondary metabolites having therapeutic importance have been reported from the genus Nocardia. One of the polyketide antibiotic compounds isolated from Nocardia is nargenicin A(1). Recently, nargenicin A(1) has been isolated from Nocardia sp. CS682, a new Nocardia strain isolated from soil in Jeonnam, South Korea. It possesses strong antibacterial activity against methicillin-resistant Staphylococcus aureus. In this study, we applied a metabolic engineering approach based on recombinant DNA technology in order to boost the production of nargenicin A(1) from Nocardia sp. CS682. Initially, we optimized the transformation of this new strain by electroporation method. Heterologous expression of S-adenosylmethionine synthetase (MetK1-sp) in Nocardia sp. CS682 enhanced the production of nargenicin A(1) by about 2.8 times due to transcriptional activation of biosynthetic genes as revealed by reverse transcription polymerase chain reaction analysis. Similarly, expression of acetyl-CoA carboxylase genes improved nargenicin A(1) production by about 3.8 times in Nocardia sp. ACC18 compared to that in Nocardia sp. CS682 and Nocardia sp. NV18 by increasing precursor pool. Thus, enhanced production of nargenicin A(1) from Nocardia sp. CS682 can be achieved by expression of transcriptional activator genes and precursor genes from Streptomyces strains.</P>
Microstrip Bandpass Filters Using Window Hairpin Resonator and T-Feeder Coupling Lines
Maharjan, R. K.,Kim, N. Y. KING FAHD UNIVERSITY OF PETROLEUM MINERALS 2014 Arabian journal for science and engineering: AJSE Vol.39 No.5
A new structure of planar window hairpin-based bandpass filters with symmetrical T-shaped feeder coupling line resonators is introduced. With varying different width in X axis and length in Y axis of the window of the hairpin resonator configuration, correspondingly the changes can be observed in the resonant frequency and useable bandwidth. By these methods, frequency tuning can be easily achieved by adjusting hairpin window dimension of the structure. Both filters were designed for 5.205 GHz resonant frequency. The geometrical window hairpin structure areas of both type filters are quite similar and both filters are resonated at almost the same frequency. The measurement results show that return loss (S-11) for both filters is higher than 23.0 dB and insertion loss (S-21) is measured less than -1.4 dB at resonant frequency of 5.13 GHz. The S-parameter responses of the fabricated filter nearly match with the electromagnetic simulated results; therefore, the feasibility of practical application of the proposed filters can be expected.
Maharjan, P.,Toyabur, R.M.,Park, J.Y. Elsevier 2018 Nano energy Vol.46 No.-
<P><B>Abstract</B></P> <P>The availability of realistic, wearable efficient energy harvesters for powering body-worn IoT devices and health monitoring sensors is essential, in order to reduce the dependence of these wearable electronic devices, on batteries. Herein, we demonstrate a novel curve-shaped wearable hybridized electromagnetic-triboelectric nanogenerator (WHEM-TENG), operating as a fully-enclosed light-weight low-frequency energy harvester, driven by human motion. The WHEM-TENG incorporates the swinging behavior of a human arm during locomotion, and the freestanding rolling mode of a magnetic ball. Simulations of the magnetic flux density and the triboelectric surface potential assisted in improving the design and performance of the nanogenerator. The harvester device was manufactured using a 3D-printing method, which makes the fabrication process faster, easier, and more cost-effective than traditional methods. The 3D-printing material was used as triboelectric material for the nanogenerator. Experiments illustrate that at the low input frequencies characteristic of walking and running, the electromagnetic generator (EMG) and triboelectric nanogenerator (TENG) deliver peak power densities of 5.14 mW/cm<SUP>3</SUP> and 0.22 µW/cm<SUP>3</SUP>, across load resistances of 49.2 Ω and 13.9 MΩ, respectively. Moreover, we also demonstrate that the WHEM-TENG can drive a commercially available electric wrist-watch continuously for 410 s from the power generated by just 5 s of running activity. Also, we demonstrate a self-powered heart-rate sensor driven by the nanogenerator. The electrical output of this distinctively structured device is promising for optimization of similar hybrid wearable energy harvesters, and for practical applications, towards the development of self-powered wearable smart bands/watches and fitness/health monitoring sensors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Human locomotion inspired novel curve-shape design is introduced as nanogenerator. </LI> <LI> Low frequency driven, light weight, fully enclosed and wrist-wearable generator. </LI> <LI> The 3d-printing method and material were used for fabrication of the nanogenerator. </LI> <LI> Converting human arm-motion energy into electrical energy to power wearable devices. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Maharjan, Pukar,Cho, Hyunok,Rasel, M. Salauddin,Salauddin, Md.,Park, Jae Yeong Elsevier 2018 Nano energy Vol.53 No.-
<P><B>Abstract</B></P> <P>Human body motion is highly regarded as a promising source of energy for powering body-worn electronic devices and health monitoring sensors. Transforming the human biomechanical energy into an electrical energy provides a sustainable energy to drive those devices and sensors, reducing their battery dependency. This work presents a fully-enclosed wrist-wearable hybridized electromagnetic-triboelectric nanogenerator (FEHN) for effectively scavenging energy from the low-frequency natural human wrist-motion (≤ 5 Hz). The FEHN incorporates the rolling electrostatic induction and electromagnetic induction using a freely moving magnetic ball inside a hollow circular tube. The materials used in 3D printing technology are used as energy harvesting material for easy, quick and worthwhile fabrication of the FEHN. A thin flexible flux concentrating material is introduced to increase the emf and enhances the electromagnetic output performance. The FEHN can harvest energy under the diverse circumstances and irregular wrist-motions, such as swinging, waving, shaking, etc. Following the experiments, the FEHN achieves an average power density of 0.118 mW cm<SUP>−3</SUP> and can drive a commercial wrist-watch continuously for more than 23 min from just 5 s of wrist motion. This successful demonstration renders an effective approach for scavenging wasted biomechanical energy and provides a promising solution towards the development of sustainable power supply for wearable electronic devices and self-powered healthcare monitoring sensors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A fully enclosed, 3D printed and hybridized nanogenerator, isolated from external environment is newly developed </LI> <LI> Sustainable nanogenerator for powering body-worn wearable electronic devices and healthcare monitoring sensors. </LI> <LI> Highly capable of harvesting energy from diverse wrist motions such as swinging, waving, shaking, twisting, etc. </LI> <LI> A flexible FeSiCr/PDMS composite based flux concentrator around the copper coil is applied to increase the induced emf. </LI> <LI> 5 s of wrist motion is enough to power a commercial electronic wrist-watch for more than 23 min continuously. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>