Surface analysis of Detonation Nanodiamond thin films fabricated using automated spray coating technique

In recent years, Detonation Nanodiamond (DND) has gained importance as a biomaterial. DND can be made into thin film coating on substrates, which is a requirement for many bioanalytical sensing devices. In this work, the distribution and thickness of DND coated as thin film on silicon substrate were studied. The coating was performed using an automated spray coating device designed for thin film deposition. The spray coated samples were compared with samples fabricated by spin coating. Scanning Electron Microscopy (SEM) was used as the analysis tool to analyse the distribution and thickness of the thin film samples. DNDs were observed as densely packed agglomerates on the surface of the thin film coatings. Agglomeration causes the DND particles to form clusters resulting in unevenness of coating surface. To prevent agglomeration and improve evenness of coating, deagglomeration is carried out using ultrasonication. The core aggregates were left intact, and the smallest observable aggregates were no less than 10nm. The thickness of DND coated thin films was measured using SEM. Thickness measurements show the coating to be uneven, which is expected to occur due to agglomeration. The average thickness of spray coating samples lies between 450 – 550 nm and that of spin coated samples lie between 200-300 nm for the same amount of solution consumption per unit area. Delamination of DND coating from Silicon substrate occurred due to the intense grinding and polishing processes during sample preparation for SEM analysis, which decreases the evenness of coating and accuracy of measurements. Improved sample preparation methods are required to obtain accurate thickness measurement using SEM. Further improvements on deagglomeration techniques might improve the distribution of DND particles, and consistency of coating thickness in DND thin film coatings. SEM has resolution power in the nanometre scale making it a good analysis tool to measure the distribution of the thin film coatings. Nevertheless, it was not possible to observe primary DND particles with good resolution below 100 nm scale using SEM. SEM along with improved sample preparation methods could possibly be a good analysis tool for thickness measurements, as it is required to fabricate measurable and repeatable thin film coatings in industrial scale

The Tradition of Akam in the Film Songs of Pa. Vijay

Tamil literature is a delight that gives immeasurable pleasure. It is a time chest that embodies the emotions of poets. Tamil literature is a never-failingly beautiful horse. From time to time, there is a new fragrance. No matter what kind of description one gives, she is a beauty that does not fall within the word. The film industry is also a part of such Tamil literature. The film industry has helped traditional poetry and new poetry to reach out to the masses not only in written form but also as a powerful weapon. This article is intended to examine how the rules and explanations laid down in the internal tradition in this field have been put in place. Although grammar is written for those who do not know the language, it is also used to recite to those who do not know the significance of our language. Thus, the purpose of this article is to study the grammar of the poems of Pa Vijay

Latent Meat (Grammar) Techniques in Nedunalvaadai

Sangam literature is the literature that can bring before our eyes the life stories of the Sangam people. The poets of the Sangam period used love genre literary techniques such as similes and metaphors to convey the love feeling as a cover-up in their poems. An implicit strategy is to make another object visible along with the apparent object. People who were in love expressed love and affection indirectly rather than directly expressing it. As far as Agam (Love Genre) literature is concerned, the techniques used to express love in the ethics of the Agam people are highly specialized. Agam People statements abound in Sangam literature. Sangam poets have created a separate space for Agam songs by respecting the love and feelings of the people. The people of Ancient Tamil transformed from an immoral life to a life of chastity. The morals of the Agam people are still the norm in people's lives today. Although the environment has changed from time to time, people still remember the messages of culture and tradition. Love and affection can be supportive of love genre literature. This research greatly supports exploring it through literary techniques such as symbolism, metaphor, and meat (grammar)

Global MPPT Control of Photovoltaic Array Using SEPIC Converter under Partial Shading Condition

The factors affecting the performance characteristics of a photovoltaic (PV) array are temperature, solar insolation, shading and array configuration. The PV system exhibits a non-linear I-V characteristic and its unique maximum power point on the P-V curve varies with insolation and temperature. The passing clouds, neighbouring buildings and trees are shadowing the PV arrays completely or partially as a result, it becomes more complex P-V characteristics with multiple peaks in case of partially shaded conditions. Conventional Maximum Power Point Tracking (MPPT) techniques fail to reach global peak power point and tend to stay in local peak power point which significantly reduces the efficiency of the PV system. This paper mainly focuses on extracting the maximum power from PV array under partially shaded conditions by executing improved hill climbing algorithm to identify the global maximum power point (GMPP) and SEPIC is used as a dc-dc interface. Simulation results have been presented to verify the performance of the proposed GMPPT techniqu

Tapering photonic crystal fibers for generating self-similar ultrashort pulses at 1550 nm

K.S.N. wishes to thank the Council of Scientific and Industrial Research [No. 03(1264)/12/EMR-11] Government of India for the financial support.Peer reviewedPublisher PD

Nearly chirp- and pedestal-free pulse compression in nonlinear fiber Bragg gratings

Peer reviewedPublisher PD

Fission-fusion dynamics and group-size dependent composition in heterogeneous populations

Many animal groups are heterogeneous and may even consist of individuals of different species, called mixed-species flocks. Mathematical and computational models of collective animal movement behaviour, however, typically assume that groups and populations consist of identical individuals. In this paper, using the mathematical framework of the coagulation-fragmentation process, we develop and analyse a model of merge and split group dynamics, also called fission-fusion dynamics, for heterogeneous populations that contain two types (or species) of individuals. We assume that more heterogeneous groups experience higher split rates than homogeneous groups, forming two daughter groups whose compositions are drawn uniformly from all possible partitions. We analytically derive a master equation for group size and compositions and find mean-field steady-state solutions. We predict that there is a critical group size below which groups are more likely to be homogeneous and contain the abundant type/species. Despite the propensity of heterogeneous groups to split at higher rates, we find that groups are more likely to be heterogeneous but only above the critical group size. Monte-Carlo simulation of the model show excellent agreement with these analytical model results. Thus, our model makes a testable prediction that composition of flocks are group-size dependent and do not merely reflect the population level heterogeneity. We discuss the implications of our results to empirical studies on flocking systems.Comment: 19 pages, 8 figure

A large deformation theory for coupled swelling and growth with application to growing tumors and bacterial biofilms

There is significant interest in modelling the mechanics and physics of growth of soft biological systems such as tumors and bacterial biofilms. Solid tumors account for more than 85% of cancer mortality and bacterial biofilms account for a significant part of all human microbial infections.These growing biological systems are a mixture of fluid and solid components and increase their mass by intake of diffusing species such as fluids and nutrients (swelling) and subsequent conversion of some of the diffusing species into solid material (growth). Experiments indicate that these systems swell by large amounts and that the swelling and growth are intrinsically coupled. However, existing theories for swelling coupled growth employ linear poroelasticity, which is limited to small swelling deformations, and employ phenomenological prescriptions for the dependence of growth rate on concentration of diffusing species and the stress-state in the system. In particular, the termination of growth is enforced through the prescription of a critical concentration of diffusing species and a homeostatic stress. In contrast, by developing a fully coupled swelling-growth theory that accounts for large swelling through nonlinear poroelasticity, we show that the emergent driving stress for growth automatically captures all the above phenomena. Further, we show that for the soft growing systems considered here, the effects of the homeostatic stress and critical concentration can be encapsulated under a single notion of a critical swelling ratio. The applicability of the theory is shown by its ability to capture experimental observations of growing tumors and biofilms under various mechanical and diffusion-consumption constraints. Additionally, compared to generalized mixture theories, our theory is amenable to relatively easy numerical implementation with a minimal physically motivated parameter space

Generation of Bragg solitons through modulation instability in a Bragg grating structure

In this article, we consider the continuous wave (cw) propagation through the nonlinear periodic structure that consists of alternating layers of both positive and negative Kerr coefficients along the propagation direction. We investigate the modulational instability (MI) conditions required for the generation of ultrashort pulses for the nonlinearity management system. We study the occurrence of MI at the top and bottom edges of the photonic band gap (PBG) where the forward and backward propagating waves are strongly coupled because of the presence of the grating structure. We also study the MI when cw is detuned from the edges of the PBG into the anomalous and normal dispersion regimes. In addition, we discuss the existence of gap solitons for the nonlinearity management system in the upper and lower branches of the dispersion curve through the MI gain spectra. We observe the generation of higher order solitons in the nonlinear periodic structure when the input power is increased beyond a certain critical level. Finally, we discuss the generation of higher order Bragg grating solitons through the intensity evolution of the forward and backward propagating fields