Solitons, Breathers and Rogue Waves in Nonlinear Media

In this thesis, the solutions of the Nonlinear Schrödinger equation (NLSE) and its hierarchy are studied extensively. In nonlinear optics, as the duration of optical pulses get shorter, in highly nonlinear media, their dynamics become more complex, and, as a modelling equation, the basic NLSE fails to explain their behaviour. Using the NLSE and its hierarchy, this thesis explains the ultra-short pulse dynamics in highly nonlinear media. To pursue this purpose, the next higher-order equations beyond the basic NLSE are considered; namely, they are the third order Hirota equation and the fifth order quintic NLSE. Solitons, breathers and rogue wave solutions of these two equations have been derived explicitly. It is revealed that higher order terms offer additional features in the solutions, namely, ‘Soliton Superposition’, ‘Breather Superposition’ and ‘Breather-to-Soliton’ conversion. How robust are the rogue wave solutions against perturbations? To answer this question, two types of perturbative cases have been considered; one is odd-asymmetric and the other type is even-symmetric. For the odd-asymmetric perturbative case, combined Hirota and Sasa-Satsuma equations are considered, and for the latter case, fourth order dispersion and a quintic nonlinear term combined with the NLSE are considered. Indeed, this thesis shows that rogue waves survive these perturbations for specific ranges of parameter values. The integrable Ablowitz-Ladik (AL) equation is the discrete counterpart of the NLSE. If the lattice spacing parameter goes to zero, the discrete AL becomes the continuous NLSE. Similar rules apply to their solutions. A list of corresponding solutions of the discrete Ablowitz-Ladik and the NLSE has been derived. Using associate Legendre polynomial functions, sets of solutions have been derived for the coupled Manakov equations, for both focusing and defocusing cases. They mainly explain partially coherent soliton (PCS) dynamics in Kerr-like media. Additionally, corresponding approximate solutions for two coupled NLSE and AL equations have been derived. For the shallow water case, closed form breathers, rational and degenerate solutions of the modified Kortweg-de Vries equation are also presented

Expression of thaumatin, a new type of alternative sweetener in rice

  Sweet proteins are the natural alternative to the artificial sweeteners as well as flavor enhancers. Among other sweet protein, thaumatin protein was isolated from Thaumatococcus daniellii Benth plant fruit. In this study, pinII Ti plasmid vector was constructed with thaumatin gene, where thaumatin was placed under the control of the duel cauliflower mosaic virus 35S promoter into rice (Oryza sativa L. var. japonica cv. ‘Dongjinbyeo’) by Agrobacterium-mediated transformation to generate transgenic plants. Thirteen plant lines were regenerated and the transgenic rice lines were confirmed by different molecular analysis. The genomic PCR result revealed that all of the plant lines were transgenic. The single copy and intergenic plant lines were selected by Taqman PCR analysis and FST analysis, respectively. Expression of thaumatin gene in transgenic rice resulted in the accumulation of thaumatin protein in the leave. Thaumatin protein was also accumulated in leave of T1 generation. Sensory analysis result suggested that the thaumatin protein expressing transgenic lines exerted sweet tasting activity. These results demonstrated that thaumatin was expressed in transgenic rice plants

A comprehensive and systemic review of ginseng-based nanomaterials: Synthesis, targeted delivery, and biomedical applications

Among 17 Panax species identified across the world, Panax ginseng (Korean ginseng), Panax quinquefolius (American ginseng), and Panax notoginseng (Chinese ginseng) are highly recognized for the presence of bioactive compound, ginsenosides and their pharmacological effects. P. ginseng is widely used for synthesis of different types of nanoparticles compared to P. quinquefolius and P. notoginseng. The use of nano-ginseng could increase the oral bioavailability, membrane permeability, and thus provide effective delivery of ginsenosides to the target sites through transport system. In this review, we explore the synthesis of ginseng nanoparticles using plant extracts from various organs, microbes, and polymers, as well as their biomedical applications. Furthermore, we highlight transporters involved in transport of ginsenoside nanoparticles to the target sites. Size, zeta potential, temperature, and pH are also discussed as the critical parameters affecting the quality of ginseng nanoparticles synthesis

Burkholderia ginsengiterrae sp. nov. and Burkholderia panaciterrae sp. nov., antagonistic bacteria against root rot pathogen Cylindrocarpon destructans, isolated from ginseng soil

Strain DCY85T and DCY85-1T, isolated from rhizosphere of ginseng, were rod-shaped, Gram-reaction-negative, strictly aerobic, catalase positive and oxidase negative. 16S rRNA gene sequence analysis revealed that strain DCY85T as well as DCY85-1T belonged to the genus Burkholderia and were closely related to Burkholderia fungorum KACC 12023T (98.1 and 98.0 % similarity, respectively). The major polar lipids of strain DCY85T and DCY85-1T were phosphatidylethanolamine, one unidentified aminolipid and two unidentified phospholipids. The major fatty acids of both strains are C16:0, C18:1ω7c and summed feature 3 (C16:1ω6c and/or C16:1ω7c). The predominant isoprenoid quinone of each strain DCY85T and DCY85-1T was ubiquinone (Q-8) and the G+C content of their genomic DNA was 66.0 and 59.4 mol%, respectively, which fulfill the characteristic range of the genus Burkholderia. The polyamine content of both DCY85T and DCY85-1T was putrescine. Although both DCY85T and DCY85-1T have highly similar 16S rRNA and identical RecA and gyrB sequences, they show differences in phenotypic and chemotaxonomic characteristics. DNA–DNA hybridization results proved the consideration of both strains as two different species. Based on the results from our polyphasic characterization, strain DCY85T and DCY85-1T are considered novel Burkholderia species for which the name Burkholderia ginsengiterrae sp. nov and Burkholderiapanaciterrae sp. nov are, respectively, proposed. An emended description of those strains is also proposed. DCY85T and DCY85-1T showed antagonistic activity against the common root rot pathogen of ginseng, Cylindrocarpon destructans. The proposed type strains are DCY85T (KCTC 42054T = JCM 19888T) and DCY85-1T (KCTC 42055T = JCM 19889T)

Characterization and Genome Analysis of Arthrobacter bangladeshi sp. nov., Applied for the Green Synthesis of Silver Nanoparticles and Their Antibacterial Efficacy against Drug-Resistant Human Pathogens

The present study describes the isolation and characterization of novel bacterial species Arthrobacter bangladeshi sp. nov., applied for the green synthesis of AgNPs, and investigates its antibacterial efficacy against drug-resistant pathogenic Salmonella Typhimurium and Yersinia enterocolitica. Novel strain MAHUQ-56T is Gram-positive, aerobic, non-motile, and rod-shaped. Colonies were spherical and milky white. The strain showed positive activity for catalase and nitrate reductase, and the hydrolysis of starch, L-tyrosine, casein, and Tween 20. On the basis of the 16S rRNA gene sequence, strain MAHUQ-56T belongs to the Arthrobacter genus and is most closely related to Arthrobacter pokkalii P3B162T (98.6%). Arthrobacter bangladeshi MAHUQ-56T has a genome 4,566,112 bp long (26 contigs) with 4125 protein-coding genes, 51 tRNA and 6 rRNA genes. The culture supernatant of Arthrobacter bangladeshi MAHUQ-56T was used for the easy and green synthesis of AgNPs. Synthesized AgNPs were characterized by UV–vis spectroscopy, FE-TEM, XRD, DLS, and FT-IR. Synthesized AgNPs were spherical and 12–50 nm in size. FT-IR analysis revealed various biomolecules that may be involved in the synthesis process. Synthesized AgNPs showed strong antibacterial activity against multidrug-resistant pathogenic S. typhimurium and Y. enterocolitica. MIC values of the synthesized AgNPs against S. typhimurium and Y. enterocolitica were 6.2 and 3.1 ug/mL, respectively. The MBC of synthesized AgNPs for both pathogens was 12.5 ug/mL. FE-SEM analysis revealed the morphological and structural alterations, and damage of pathogens treated by AgNPs. These changes might disturb normal cellular functions, which ultimately leads to the death of cells

Biologically rapid synthesis of silver nanoparticles by Sphingobium sp. MAH-11T and their antibacterial activity and mechanisms investigation against drug-resistant pathogenic microbes

AbstractThe present study highlights the biological synthesis of silver nanoparticles (AgNPs) using Sphingobium sp. MAH-11 and also their antibacterial mechanisms against drug-resistant pathogenic microorganisms. The nanoparticle synthesis method used in this study was reliable, facile, rapid, cost-effective and ecofriendly. The AgNPs exhibited the highest absorbance at 423 nm. The TEM image expressed spherical shape of AgNPs and the size of synthesized AgNPs was 7–22 nm. The selected area diffraction (SAED) pattern and XRD spectrum revealed the crystalline structure of AgNPs. The results of FTIR analysis disclosed the functional groups responsible for the reduction of silver ion to metal nanoparticles. The biosynthesized AgNPs showed strong anti-microbial activity against drug-resistant pathogenic microorganisms. Moreover, Escherichia coli and Staphylococcus aureus were used to explore the antibacterial mechanisms of biosynthesized AgNPs. Minimal inhibitory concentrations (MICs) of E. coli and S. aureus were 6.25 μg/mL and 50 μg/mL, respectively and minimum bactericidal concentrations (MBCs) of E. coli and S. aureus were 25 μg/mL and 100 μg/mL, respectively. Results exhibited that biosynthesized AgNPs caused morphological changes and injured the membrane integrity of strains E. coli and S. aureus. The AgNPs synthesized by Sphingobium sp. MAH-11 may serve as a potent antimicrobial agent for many therapeutic applications

Biosynthesis, Characterization and Antibacterial Application of Novel Silver Nanoparticles against Drug Resistant Pathogenic Klebsiella pneumoniae and Salmonella Enteritidis

The present study highlights the biosynthesis of silver nanoparticles (AgNPs) using culture supernatant of Massilia sp. MAHUQ-52 as well as the antimicrobial application of synthesized AgNPs against multi-drug resistant pathogenic Klebsiella pneumoniae and Salmonella Enteritidis. Well-defined AgNPs formation occurred from the reaction mixture of cell-free supernatant and silver nitrate (AgNO3) solution within 48 h of incubation. UV-visible spectroscopy analysis showed a strong peak at 435 nm, which corresponds to the surface plasmon resonance of AgNPs. The synthesized AgNPs were characterized by FE-TEM, EDX, XRD, DLS and FT-IR. From FE-TEM analysis, it was found that most of the particles were spherical shape, and the size of synthesized nanoparticles (NPs) was 15–55 nm. EDX spectrum revealed a strong silver signal at 3 keV. XRD analysis determined the crystalline, pure, face-centered cubic AgNPs. FT-IR analysis identified various functional molecules that may be involved with the synthesis and stabilization of AgNPs. The antimicrobial activity of Massilia sp. MAHUQ-52 mediated synthesized AgNPs was determined using the disk diffusion method against K. pneumoniae and S. Enteritidis. Biosynthesized AgNPs showed strong antimicrobial activity against both K. pneumoniae and S. Enteritidis. The MICs of synthesized AgNPs against K. pneumoniae and S. Enteritidis were 12.5 and 25.0 μg/mL, respectively. The MBC of biosynthesized AgNPs against both pathogens was 50.0 μg/mL. From FE-SEM analysis, it was found that the AgNPs-treated cells showed morphological changes with irregular and damaged cell walls that culminated in cell death

Probiotic-Mediated Biosynthesis of Silver Nanoparticles and Their Antibacterial Applications against Pathogenic Strains of <i>Escherichia coli</i> O157:H7

The present study aimed to suggest a simple and environmentally friendly biosynthesis method of silver nanoparticles (AgNPs) using the strain Bacillus sonorensis MAHUQ-74 isolated from kimchi. Antibacterial activity and mechanisms of AgNPs against antibiotic-resistant pathogenic strains of Escherichia coli O157:H7 were investigated. The strain MAHUQ-74 had 99.93% relatedness to the B. sonorensis NBRC 101234T strain. The biosynthesized AgNPs had a strong surface plasmon resonance (SPR) peak at 430 nm. The transmission electron microscope (TEM) image shows the spherical shape and size of the synthesized AgNPs is 13 to 50 nm. XRD analysis and SAED pattern revealed the crystal structure of biosynthesized AgNPs. Fourier transform infrared spectroscopy (FTIR) data showed various functional groups associated with the reduction of silver ions to AgNPs. The resultant AgNPs showed strong antibacterial activity against nine E. coli O157:H7 pathogens. Minimum inhibitory concentration (MIC) values of the AgNPs synthesized by strain MAHUQ-74 were 3.12 μg/mL for eight E. coli O157:H7 strains and 12.5 μg/mL for strain E. coli ATCC 25922. Minimum bactericidal concentrations (MBCs) were 25 μg/mL for E. coli O157:H7 ATCC 35150, E. coli O157:H7 ATCC 43895, E. coli O157:H7 ATCC 43890, E. coli O157:H7 ATCC 43889, and E. coli ATCC 25922; and 50 μg/mL for E. coli O157:H7 2257, E. coli O157: NM 3204-92, E. coli O157:H7 8624 and E. coli O157:H7 ATCC 43894. FE-SEM analysis demonstrated that the probiotic-mediated synthesized AgNPs produced structural and morphological changes and destroyed the membrane integrity of pathogenic E. coli O157:H7. Therefore, AgNPs synthesized by strain MAHUQ-74 may be potential antibacterial agents for the control of antibiotic-resistant pathogenic strains of E. coli O157:H7

Green Synthesis and Potential Antibacterial Applications of Bioactive Silver Nanoparticles: A Review

Green synthesis of silver nanoparticles (AgNPs) using biological resources is the most facile, economical, rapid, and environmentally friendly method that mitigates the drawbacks of chemical and physical methods. Various biological resources such as plants and their different parts, bacteria, fungi, algae, etc. could be utilized for the green synthesis of bioactive AgNPs. In recent years, several green approaches for non-toxic, rapid, and facile synthesis of AgNPs using biological resources have been reported. Plant extract contains various biomolecules, including flavonoids, terpenoids, alkaloids, phenolic compounds, and vitamins that act as reducing and capping agents during the biosynthesis process. Similarly, microorganisms produce different primary and secondary metabolites that play a crucial role as reducing and capping agents during synthesis. Biosynthesized AgNPs have gained significant attention from the researchers because of their potential applications in different fields of biomedical science. The widest application of AgNPs is their bactericidal activity. Due to the emergence of multidrug-resistant microorganisms, researchers are exploring the therapeutic abilities of AgNPs as potential antibacterial agents. Already, various reports have suggested that biosynthesized AgNPs have exhibited significant antibacterial action against numerous human pathogens. Because of their small size and large surface area, AgNPs have the ability to easily penetrate bacterial cell walls, damage cell membranes, produce reactive oxygen species, and interfere with DNA replication as well as protein synthesis, and result in cell death. This paper provides an overview of the green, facile, and rapid synthesis of AgNPs using biological resources and antibacterial use of biosynthesized AgNPs, highlighting their antibacterial mechanisms