Chemical solvents are commonly used to prevent microbial growth; dangerous to human health and have limited antibacterial properties. On the other hand, Nanoparticles made of metallic elements (such as copper, silver, and gold) have several uses in the field of biotechnology. Silver nanoparticles are more efficient in their antimicrobial, antibacterial, anti-inflammatory and anti-cancer properties. The current study aimed to determine the green synthesis of silver nanoparticles and their antibacterial activity from the aqueous extracts of leaves of Couroupita guianensis, Punica granatum, Vitex negundo, Cirtrus maxima. AgNPs of plant extracts were prepared using silver nitrate with the respective plant extract. Then they were characterized by FTIR analysis. The respective functional groups in the synthesized silver nanoparticles were confirmed with FTIR Spectra. The antibacterial activities of the synthesized nanoparticle extract were observed by zone of inhibition. From the results, the nanoparticles synthesized from the plants extract could pave a way to formulate a drug to treat microbial infection.

Cellulose nanofiber is an eco-friendly nanomaterial used for fabricating various functional materials. It is an alternative for synthetic plastic and other petroleum derived materials. Due to demand of CNF film, fast and rapid method for fabrication of CNF film is required. A new method on spray coating to prepare smooth cellulose nanofiber (CNF) films was developed. In this method, spraying CNF suspension onto a smooth and polished metal surface was carried out and then allowed the spray coated wet film to dry in air under standard laboratory conditions. Spraying has notable advantages such as contour coating and contactless coating with the base substrate. The basis weight and thickness of the CNF film is tailorable by adjusting CNF suspension in spraying process. CNF film prepared via spray coating has unique two-sided surface roughness with the surface in contact with the base substrate or metal side much smoother than the air-contact side. The surface roughness is one of the controlling parameter in the application of the CNF film as a substrate for flexible and printed electronics. The RMS roughness of the two surfaces investigated by Optical Profilometry [OP] was found to be 2087 nm on the rough side and 389 nm on the spray coated side, respectively. The spray coated CNF film has ultra-high smoothness on the side exposed to the polished stainless steel surface. The factors including the size of cellulose fibrils and surface smoothness of base surface that control the roughness of the film are currently being investigated and will be discussed in this chapter. The surface smoothness requirements for substrate applications in flexible and printed electronics will be discussed.

Paper is widely used in packaging applications and is biodegradable and therefore perfectly safe as green packaging wrap for the environment. The hydrophilic nature of cellulose fibrils limits the water vapour and oxygen barrier properties of paper. To mitigate these limitations, paper is often associated with other materials, such as plastics, wax and aluminum, for achieving their good barrier properties. However, these materials suffer from serious environmental issues, as difficult and inefficient to recycle. Recently, cellulose nanofibre (CNF) based materials has been considered as an alternative to produce eco-friendly barrier materials. Existing techniques to prepare cellulose nanofibre films/sheets/composites/ laminates on the paper substrates are commercially not feasible and expensive. Therefore, other cost effective and readily implementable methodologies are required to achieve cellulose nanofibre barrier layers. In the present report, a novel approach is developed using spray coating technique to produce CNF materials with excellent barrier properties. Among many coating techniques, the spray coating has many advantages such as the production of even coating surface on the base sheet and contactless coating with the substrate. A laboratory scale spray coating of cellulose nanofibre suspension on a paper substrate was developed. When the cellulose nanofibre suspension concentration was varied from 0.5 to 1.5 wt. %, coat weight is increased from 2.9±0.7 to 29.3±6.9 g/m². As a result, the air permeability of composite was decreased 0.78±0.17 to <0.0030 µm/Pa.s. Scanning electron microscopy studies of spray coated CNF laminates on the paper confirms that the surface pores in the paper substrates are filled with sprayed cellulose nanofibre and forms a continuous film on the surface of the substrate. These are the probable reasons for the reduction of air permeability of composites. A rapid preparation technique to prepare free standing cellulose nanofibre films/sheets was also developed using a bench scale spray coating system. Cellulose nanofibre suspension with concentration ranging from 1 to 2 wt% was sprayed onto a stainless steel plate, which is moving on a conveyor at a velocity of 0.32 cm/sec and then air dried. The basis weight of produced cellulose nanofibre films is varied from 52.8±7.4 to 193.1±3.4 g/m². Processing time taken to prepare films was approximately 1.0 min, which is much less than processing times reported in the previous literature. Thus, the significant reduction in preparation time for producing the cellulose nanofibre sheet recommends that this spray coating technique can be utilized for the development of a scalable process for the fabrication of various cellulose based nanocomposite. Therefore, the laboratory scale spray coating confirms that the spraying could provide a platform for development of films/sheets/nanocomposite and also a CNF barrier layer on the base sheet. The future work is the development of a continuous spray coating of cellulose nanofibre on the base sheet and evaluation of mechanical and barrier properties spray coated barrier layers on the base sheet.

In this study, the system identification of a multiple input multiple-output (MIMO) water tank has been investigated. The given experimental system is a first-order system. Its transfer function was evaluated and the time constant was predicted. Once the parameters of the transfer functions (delay, gain, and time constant) were determined for each step input. This model each of the step responses using MatLab’s Simulink. These simulated responses were then compared to the observed experimental responses.