Chandigarh University

About: Chandigarh University is a education organization based out in Mohali, India. It is known for research contribution in the topics: Materials science & Computer science. The organization has 1358 authors who have published 2104 publications receiving 10050 citations.

Effects of meso-M(PPh3)2Cl (M = Pd, Ni) substituents on the linear and third-order nonlinear optical properties of chalcogenopyrylium-terminated heptamethines in solution and solid states

Abstract: Aggregation of cyanine-like dyes can significantly affect their optical properties. Here we report the effects of bulky meso-M(PPh3)2Cl (M = Pd, Ni) substitution on the molecular and solid-state optical characteristics of chalcogenopyrylium-terminated heptamethines. Metallated dyes were synthesised by reaction of the meso-chloro dyes with Pd(PPh3)4 or Ni(PPh3)4 at room temperature. The two PPh3 ligands are trans and the plane formed by the metal atom and its ligands is approximately orthogonal to that of the polymethine π-system. Replacement of Cl by M(PPh3)2Cl leads to a large blue shift of the solution absorption maximum and a decrease in the associated transition dipole moment, these effects being slightly more pronounced for Ni than for Pd. DFT calculations and electrochemical data suggest the blue shifts can largely be attributed to destabilisation of the LUMO by the more strongly π-donating M(PPh3)2Cl groups. The magnitude of the real part of the molecular third-order polarisability, Re(γ), decreases in the order Cl > Pd(PPh3)2Cl ≫ Ni(PPh3)2Cl. Within the framework of the sum-over-states expression for Re(γ), the difference between Cl and Pd(PPh3)2Cl examples can be rationalised considering the effects of the S0 → S1 transition energy and transition dipole moment on the two-state term associated with S0 → S1. On the other hand, the magnitude of Re(γ) for a Ni(PPh3)2Cl dye is anomalously low; SAC-CI/HF/cc-pVDZ excited-state calculations reveal this is due to a two-photon-allowed S2 state at unusually low energy for a cyanine-like dye, leading to a large positive three-state contribution to γ opposing the negative two-state S1 term. Thus, despite a cyanine-like molecular structure and linear absorption spectrum, this compound does not exhibit cyanine-like nonlinear optical behavior. Turning to the effects on aggregation, molecular dynamics simulations suggest that Pd(PPh3)2Cl substitution largely suppresses H- and J-aggregate formation; indeed experimental absorption spectra for neat films of Pd(PPh3)2Cl-substituted dyes are fairly similar to corresponding solution spectra. A 50 wt% blend of a Pd(PPh3)2Cl-substituted telluropyrylium-terminated dye with amorphous polycarbonate exhibits a third-order susceptibility of −3 × 10−11 esu, a two-photon figure-of-merit in excess of 10, and linear loss of 6.3 dB cm−1, which are close to the requirements for all-optical switching applications.

Experimental investigations into machining performance of Hastelloy C-276 in different cooling environments

Abstract: Machining of difficult to cut materials at advanced range of machining variable is the requirement of industry 4.0 for achieving sustainable machining goals taking into consideration energy, ecolog...

In Situ Copolymerized Polyacrylamide Cellulose Supported Fe3O4 Magnetic Nanocomposites for Adsorptive Removal of Pb(II): Artificial Neural Network Modeling and Experimental Studies.

Abstract: The inimical effects associated with heavy metals are serious concerns, particularly with respect to global health-related issues, because of their non-ecological characteristics and high toxicity. Current research in this area is focused on the synthesis of poly(acrylamide) grafted Cell@Fe3O4 nanocomposites via oxidative free radical copolymerization of the acrylamide monomer and its application for the removal of Pb(II). The hybrid material was analyzed using different analytical techniques, including thermogravimetric analysis (TGA), Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) analysis. The efficacious impact of variable parameters, including contact time, pH, material dose, initial Pb(II) concentration, and the temperature, was investigated and optimized using both batch and artificial neural networks (ANN). Surface digestion of metal ions is exceedingly pH-dependent, and higher adsorption efficiencies and adsorption capacities of Pb(II) were acquired at a pH value of 5. The acquired equilibrium data were analyzed using different isotherm models, including Langmuir, Freundlich, Temkin, and Redlich-Peterson models. In this investigation, the best performance was obtained using the Langmuir model. The maximum adsorption capacity of the material investigated via monolayer formation was determined to be 314.47 mg g-1 at 323 K, 239.74 mg g-1 at 313 K, and 100.79 mg g-1 at 303 K.

An Adaptive Grid Frequency Support Mechanism for Energy Management in Cloud Data Centers

Abstract: Grid frequency support is one of the most challenging problems, since minor variations in it may lead to huge financial losses. This problem becomes even more challenging with the horizontal and vertical expansion of modern cloud data centers (DCs). In the past, several efforts have been made to manage frequency deviations using flywheels, commercial buildings, electric vehicles, and renewable energy resources. However, these are not adequate due to their complex operations. To fill these gaps, in this paper, we propose the usage of cloud DCs and uninterruptible power supply (UPS) units for the effective frequency regulation. This is achieved by designing a 2-layer hierarchical control scheme for optimal segregation of the regulation signals amongst the DCs and UPS batteries. The proposed scheme determines the scheduling policy for jobs at DCs; along with the charging and discharging cycles of the UPS batteries. The job scheduling is carried out with respect to MapReduce tasks in accordance with the regulation signals with minimal service level adherence violations. Additionally, the sustainability of DCs is also supported through active participation of UPSes during peak hours. The overall frequency support problem in the considered setup involves multiple objectives under multiconstraint environment. Thus, it has been divided in two subproblems, which are addressed individually using either integer linear programming or mixed integer linear programming. In a nutshell, the proposed scheme serves dual purposes, i.e., manages frequency fluctuations and sustains DCs during peak hours. It has been validated using data traces taken from OpenCloud Hadoop cluster and Pennsylvania New Jersey Maryland. The results obtained prove the effectiveness of the proposed scheme for frequency support and DC's sustainability.