Indian Institute of Technology Ropar

About: Indian Institute of Technology Ropar is a education organization based out in Ropar, India. It is known for research contribution in the topics: Catalysis & Computer science. The organization has 1014 authors who have published 2878 publications receiving 35715 citations.

Slurry Erosive Wear Evaluation of HVOF-Spray Cr 2 O 3 Coating on Some Turbine Steels

Abstract: In this study, Cr2O3 coatings were deposited on CF8M and CA6NM turbine steels by high-velocity oxy-fuel (HVOF)-spray process and analyzed with regard to their performance under slurry erosion conditions. High Speed Erosion Test Rig was used for slurry erosion tests, and the effects of three parameters, namely, average particle size, speed (rpm), and slurry concentration on slurry erosion of these materials were investigated. SEM micrographs on the surface of samples, before and after slurry erosion tests, were taken to study the erosion mechanism. For the uncoated steels, CA6NM steel showed better erosion resistance in comparison with CF8M steel. The HVOF-sprayed Cr2O3-coated CF8M and CA6NM steels showed better slurry erosion resistance in comparison with their uncoated counterparts. It may be due to the higher hardness as a result of HVOF-sprayed Cr2O3 coating in comparison with the uncoated CF8M and CA6NM steels.

ZnO-Based Imine-Linked Coupled Biocompatible Chemosensor for Nanomolar Detection of Co2+

Abstract: A sol–gel process is developed for the synthesis of ZnO crystals at room temperature using organic receptors (bearing imine linkages) as the capping agents to control the size and shape of ZnO. The size and morphology of ZnO are characterized with X-ray diffraction, TEM, SEM, and DLS studies. The decoration of imine-linked receptors on the surface of ZnO is characterized with IR and NMR spectroscopy and confirmed with EDX analysis. The XRD results show that the average crystallite size of ZnO is 13.8 nm with a hexagonal wurtzite structure. Fluorescence spectroscopy revealed that surface-coated ZnO possesses fewer surface defects than the usual bulk ZnO. The imine-linked receptor-coated ZnO (sensor) was tested for recognition of various metal ions; however, the sensor was found to be selective for Co2+ in the DMSO/H2O (8:2; v/v) solvent system. The successive addition of Co2+ to the solution of the sensor quenches the fluorescence intensity at 445 nm with enhancement at 353 nm. This leads to the developmen...

Stochasticity and bistability in insect outbreak dynamics

Abstract: There is a long history in ecology of using mathematical models to identify deterministic processes that may lead to dramatic population dynamic patterns like boom-and-bust outbreaks. Stochasticity is also well-known to have a significant influence on the dynamics of many ecological systems, but this aspect has received far less attention. Here, we study a stochastic version of a classic bistable insect outbreak model to reveal the role of stochasticity in generating outbreak dynamics. We find that stochasticity has strong effects on the dynamics and that the stochastic system can behave in ways that are not easily anticipated by its deterministic counterpart. Both the intensity and autocorrelation of the stochastic environment are important. Stochasticity with higher intensity (variability) generally weakens bistability, causing the dynamics to spend more time at a single state rather than jumping between alternative stable states. Which state the population tends toward depends on the noise color. High-intensity white noise causes the insect population to spend more time at low density, potentially reducing the severity or frequency of outbreaks. However, red (positively autocorrelated) noise can make the population spend more time near the high density state, intensifying outbreaks. Under neither type of noise do early warning signals reliably predict impending outbreaks or population crashes.