Low‐Temperature Growth of Carbon Nanotubes Catalyzed by Sodium‐Based Ingredients

Synthesis of low‐dimensional carbon nanomaterials such as carbon nanotubes (CNTs) is a key driver for achieving advances in energy storage, computing, and multifunctional composites, among other applications. Here, we report high‐yield thermal chemical vapor deposition (CVD) synthesis of CNTs catalyzed by reagent‐grade common sodium‐containing compounds, including NaCl, NaHCO₃, Na₂CO₃, and NaOH, found in table salt, baking soda, and detergents, respectively. Coupled with an oxidative dehydrogenation reaction to crack acetylene at reduced temperatures, Na‐based nanoparticles have been observed to catalyze CNT growth at temperatures below 400 °C. Ex situ and in situ transmission electron microscopy (TEM) reveal unique CNT morphologies and growth characteristics, including a vaporizing Na catalyst phenomenon that we leverage to create CNTs without residual catalyst particles for applications that require metal‐free CNTs. Na is shown to synthesize CNTs on numerous substrates, and as the first alkali group metal catalyst demonstrated for CNT growth, holds great promise for expanding the understanding of nanocarbon synthesis.     

Chaotic behavior of logistic map in superior orbit and an improved chaos-based traffic control model

With a vital role of discrete chaos, standard logistic map has found a celebrated place in the dynamics of chaos theory and in various applications of science, such as a discrete traffic flow model, image encryption in cryptography, secure communication, and weather forecasting. Traditionally, this discrete chaos is controlled by one parameter \(\lambda \) using Picard orbit, a one-step feedback procedure. This article presents a one-step forward, applying Mann orbit (superior orbit) the chaotic properties such as period-doubling, period-3 window, and Lyapunov exponent of the standard logistic map is investigated. The results are illustrated analytically and experimentally followed by concluding remarks and a few counter examples. Due to the extra degree of freedom in parameter \(\lambda \), the map provides improved chaotic properties that increases the performance of dynamical phenomena. Moreover, this study describes an improved chaos-based discrete traffic control model. Surprisingly, added new parameter \(\alpha \) in Mann orbit works as control variable that increases the stability performance of the traffic model.     

Label-free and rapid spectroscopic evaluation of ripening of Syzygium cumini fruit

In the present investigation, attempts have been made to obtain the spectral signature of the fruit jamun and to estimate the changes in biochemical composition that take place in the process of ripening of the fruits. The changes in exocarp, mesocarp, and seed of the fruit in raw and ripe stages have been investigated with the help of label-free, nondestructive, and rapid techniques: laser-induced fluorescence and attenuated total reflectance Fourier transform infrared spectroscopy. For this, the fluorescence spectra of the different parts (exocarp, mesocarp, and seed) of the raw and ripe fruits of jamun excited by 405?nm violet diode laser have been recorded in the spectral region 400–900?nm. The spectrum shows the spectral signature of anthocyanin, flavonoids, carotenoid, and chlorophyll. The observed decrease in the intensity of chlorophyll bands and simultaneous increase in the intensity of anthocyanin and carotenoid bands is regarded as indicator of the ripening of the fruit of jamun. Also, attenuated total reflectance Fourier transform infrared spectra have been recorded in the spectral region 4000–485?cm^?1 for the identification of functional groups associated with different biochemical altered during ripening process of the fruits of jamun. The analyses of the recorded infrared spectra show the presence of carbohydrates, cell wall components, phenolic compounds, nucleic acid, and amide. The quantitative estimation of the biochemical content in the different parts of jamun fruit during the ripening process has been done through calculating the area of the band by curve fitting. The determined spectral signatures can be utilized for the effective monitoring of jamun fruit.     

Structural and optical properties of AlN/Si system

Aluminum nitride (AlN) is a wide band gap III–V semiconductor material which is often used for optical applications. Thin films of aluminum nitride were deposited by ion beam sputtering in an Ar–N₂ atmosphere on Si (1 0 0). For film preparation, the N₂ flow was kept at 5 sccm and the ratio of N₂ and Ar was 4:1. The films have been characterized by Grazing Incidence X-ray Diffraction (GIXRD), X-ray Reflectometry (XRR), Atomic Force Microscopy (AFM) and optical spectroscopy. GIXRD shows that the structure of the as-deposited sample of AlN is hexagonal. It is observed that neither the ion-beam-induced dissociation of the nitride film nor the enhanced nitrogen diffusion across the interface takes place after Au ion irradiation. XRR was used to determine the thickness of the films. The reflectance of the irradiated films increases in the range 200–280 nm. UV–vis spectra were taken in Kubelka Munk (KM) units for as-deposited and irradiated samples. The band gap was calculated for both types of samples, which shows that the band gap of irradiated films of aluminum nitride decreases due to the increase in metal content at the surface. AFM confirms that the roughness of aluminum nitride increases by irradiation.     

Total Synthesis of an Experimental Antitubercular Drug CDRI-830

The triarylmethane antituberculosis drug CDRI-830 is synthesized. The triarylmethane derivative 4 is prepared from ether 6 by a rearrangement process. The total synthesis of the drug CDRI-830 is achieved in a good overall yield of 35% from a simple thiophene derivative 8.     

Finite nets of dimension d

This paper introduces the concept of a finite net of dimension d. This is a generalization of the finite net of dimension three, due to Laskar and the finite net (of dimension two) due to Bruck. An association scheme is defined on this system which is then shown to form a partially balanced incomplete block design on an association scheme with d associate classes.     

On powers and centers of chordal graphs

A graph is chordal if every cycle of length strictly greater than three has a chord. A necessary and sufficient condition is given for all powers of a chordal graph to be chordal. In addition, it is shown that for connected chordal graphs the center (the set of all vertices with minimum eccentricity) always induces a connected subgraph. A relationship between the radius and diameter of chordal graphs is also established.     

A simple method for optimal redundancy allocation for complex networks

In this paper a simple method for optimum redundancy allocation for complex networks is presented. A new heuristic criterion is introduced for solving the problem by decomposing the same in two phases. After finding all minimal path sets of the system in phase I, we choose a minimal path set having the highest value of the ‘sensitivity factor’. In phase II we add one component to the stage having the largest value of the selection factor amongst the stages of the selected minimal path set. This procedure is continued until no more redundant component can be added within the available resources. The proposed method is simple, easily computerizable, fast and capable of handling problems subject to any number of constraints. The method has been illustrated by examples and results are compared with the existing methods.