Krishnan Balasubramanian

Bio: Krishnan Balasubramanian is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Propellant & Graphene. The author has an hindex of 3, co-authored 11 publications receiving 41 citations.

Closed-cage tungsten oxide clusters in the gas phase.

Abstract: During the course of a study on the clustering of W−Se and W−S mixtures in the gas phase using laser desorption ionization (LDI) mass spectrometry, we observed several anionic W−O clusters. Three distinct species, W6O19−, W13O29−, and W14O32−, stand out as intense peaks in the regular mass spectral pattern of tungsten oxide clusters suggesting unusual stabilities for them. Moreover, these clusters do not fragment in the postsource decay analysis. While trying to understand the precursor material, which produced these clusters, we found the presence of nanoscale forms of tungsten oxide. The structure and thermodynamic parameters of tungsten clusters have been explored using relativistic quantum chemical methods. Our computed results of atomization energy are consistent with the observed LDI mass spectra. The computational results suggest that the clusters observed have closed-cage structure. These distinct W13 and W14 clusters were observed for the first time in the gas phase.

Graphene functionalized carbon nanotube polymer composites and methods for their preparation and use

Abstract: Methods of forming graphene functionalized carbon nanotube polymer composites are provided. The methods can include functionalizing a plurality of carbon nanotubes using conducting functional molecules to form a composite nanofiller and embedding the composite nanofiller within a polymer material to form the graphene functionalized carbon nanotube polymer composite.

Investigation of the Directional Response of Fibre Bragg Grating-Based Acoustic Emission Sensor

Abstract: We investigate the directional response of fiber Bragg gratings to acoustic emissions using a home built dynamic interrogator capable of sensing acoustic emissions from few kHz to 1 MHz.

Piezoresistive type graphene nano platelet sensor for SHM application in structural components

Abstract: With the advancement of science and technology, SHM application through smart materials from graphene are becoming more popular than ever before. The physics behind graphene sensor has become an area of suitable interest owing to its Non-destructive application in structural components. Smart material sensors being allotrope form of carbon has been basically used for piezoresistive application purposes in composites, environmental monitoring and also in health applications. Here Gnp (graphene nano platelet) sensor has been used for SHM monitoring in structural components. We employed various Non-destructive methods such as SEM spectroscopy, Raman spectroscopy to find out sensor’s characterization in straining action associated with structural components with the help of GNP sensor.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Bifunctional H2WO4/TS-1 catalysts for direct conversion of cyclohexane to adipic acid: Active sites and reaction steps

Abstract: Adipic acid production may account for 10% of the annual increase in atmospheric nitrous oxide level. Here we developed a hollow H 2 WO 4 /TS-1 bifunctional catalyst with excellent catalytic activity for the direct transformation of cyclohexane to adipic acid with 30% hydrogen peroxide by a non-HNO 3 route. XRD diffraction, N 2 physisorption, TEM, NH 3 -TPD and Raman, XPS, Infrared, and UV–visible spectroscopies were used to characterize catalysts to increase understanding of the structure of active species on the hollow TS-1 support. The enhanced catalytic activity in comparison of reference catalysts (H 2 WO 4 , H 2 WO 4 /Silicate-1 and TS-1) was explained in terms of their bifunctional catalytic sites and perfect hollow morphology with large intraparticle voids. Experimental results on the product distribution indicated that the tetrahedral Ti and surface W sites played important roles in the synergistic effect: tetrahedral Ti worked in oxidation of cyclohexane to intermediates (cyclohexanone and cyclohexanol) and surface W worked in further oxidation of late intermediates to adipic acid. Theoretical calculation results on catalytic activity of the Ti O O H and W O O H active sites in the H 2 WO 4 /TS-1 for different reaction steps validate the experimental results. The catalytic activity was also correlated to the strong interaction between W sites and HTS-1 surface induced increase in acidity of the materials. Increasing calcination temperature led to structural evolution of supported active species and subsequent activity change. A cyclohexane conversion of 31% with 78% adipic acid selectivity was achieved over this catalyst calcinated at 500 ∘C. Based on the catalytic and characterization results, possible reaction pathways were thus proposed to explain high adipic acid yield over hollow H 2 WO 4 /TS-1 catalysts.

Density Functional Calculation of the Structure and Electronic Properties of CunOn (n = 1−8) Clusters

Abstract: Ab initio simulations and calculations were used to study the structures and stabilities of copper oxide clusters, Cu n O n (n = 1―8). The lowest energy structures of neutral and charged copper oxide clusters were determined using primarily the B3LYP/ LANL2DZ model chemistry. For n ≥ 4, the clusters are nonplanar. Selected electronic properties including atomization energies, ionization energies, electron affinities, and Bader charges were calculated and examined as a function of n.

Effect of aluminum nanoparticles on rheological behavior of HTPB-based composite rocket propellant

Abstract: The aim of this article was to understand the rheology of composite propellant containing aluminum nanoparticles, as it is a highly filled mixture of solids and is difficult to process. Aluminum na...