A study of nerve agent model organophosphonate binding with manganese-A₂B-corrole and -A₂B₂-porphyrin systems

Kim, K.,Kim, I.,Maiti, N.,Kwon, S.J.,Bucella, D.,Egorova, O.A.,Lee, Y.S.,Kwak, J.,Churchill, D.G. Pergamon Press 2009 Polyhedron Vol.28 No.12

Herein the synthesis and binding studies of novel trans-A<SUB>2</SUB>B-corrole and trans-A<SUB>2</SUB>B<SUB>2</SUB>-porphyrin derivatives are presented in comparing manganese(III)-organophosphonate (OP) binding (e.g., M<SUP>n+</SUP>←O?PR(OR)<SUB>2</SUB>) capabilities. H<SUB>3</SUB>(PFP-VC) [PFP-VC=5,15-di(pentafluorophenyl)-10-(3-vinylphenyl)corrolate] was synthesized by way of literature procedures and was characterized by a variety of 2-D NMR spectroscopic techniques and single-crystal X-ray diffraction. These compounds represent the first example of 3-vinyl-phenyl-containing meso-substituted corroles or porphyrins. Mn(PFP-VC) (3) was treated separately with (CH<SUB>3</SUB>CH<SUB>2</SUB>O)<SUB>2</SUB>P?O(C<SUB>3</SUB>H<SUB>6</SUB>NMe<SUB>2</SUB>), (C<SUB>4</SUB>H<SUB>9</SUB>O)<SUB>2</SUB>P?O(Me), (C<SUB>2</SUB>H<SUB>5</SUB>O)<SUB>2</SUB>P?O(CH<SUB>2</SUB>COCH<SUB>3</SUB>), (CH<SUB>3</SUB>CH<SUB>2</SUB>O)<SUB>2</SUB>P?O(Me), to give 1:1 adducts, as determined by UV-Vis spectroscopy (Job Plot), giving a red shift; Ph<SUB>3</SUB>P?O, was also found to bind, but very weakly. The trans-A<SUB>2</SUB>B<SUB>2</SUB>-porphyrin analogue Mn(PFP-VP) (4) was also prepared by way of a literature procedure; related binding studies gave 1:1 organophosphonate-Mn(PFP-VP) adducts (Job Plot). A clean blue shift occurred for the Mn-porphyrins at higher organophosphonate loadings (K<SUB>a</SUB> values: 6.7 (0.9)-11.9 (0.4)M<SUP>-1</SUP>). DFT geometry optimizations of O?P(OMe)<SUB>2</SUB>Me binding and formal Mn-O or P-O cleavage products in the unsubstituted neutral Mn-corrolato and -porphyrinato systems with a range of metal-based spin states revealed greatest stability in formal phosphoryl oxygen binding (energies: 11-13kcal/mol) for the Mn-corrole (singlet); the Mn-porphyrin (sextet) was also quite stable.

Differential Effects of Gonadotropin-Releasing Hormone (GnRH)-I and GnRH-II on Prostate Cancer Cell Signaling and Death

Maiti, K.,Oh, D. Y.,Moon, J. S.,Acharjee, S.,Li, J. H.,Bai, D. G.,Park, H.-S.,Lee, K.,Lee, Y. C.,Jung, N. C. ENDOCRINE SOCIETY 2005 The Journal of clinical endocrinology & metabolism Vol.90 No.7

Active vibration control of smart composite structures in hygrothermal environment

P.K. Mahato,D.K. Maiti 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.2

The composite materials may be exposed to environmental (thermal or hygral or both) condition during their service life. The effect of environmental condition is usually adverse from the point of view of design of composite structures. In the present research study the effect of hygrothermal condition on the design of laminated composite structures is investigated. The active fiber composite (AFC) which may be utilized as actuator or sensor is considered in the present analysis. The sensor layer is used to sense the level of response of the composite structures. The sensed voltage is fed back to the actuator through the controller. In this study both displacement and velocity feedback controllers are employed to reduce the response of the composite laminate within acceptable limit. The Newmark direct time integration scheme is employed along with modal superposition method to improve the computational efficiency. It is observed from the numerical study that the laminated composite structures become weak in the presence of hygrothermal load. The response of the structure can be brought to the acceptable level once the AFC layer is activated through the feedback loop.

Active vibration control of smart composite structures in hygrothermal environment

Mahato, P.K.,Maiti, D.K. Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.2

The composite materials may be exposed to environmental (thermal or hygral or both) condition during their service life. The effect of environmental condition is usually adverse from the point of view of design of composite structures. In the present research study the effect of hygrothermal condition on the design of laminated composite structures is investigated. The active fiber composite (AFC) which may be utilized as actuator or sensor is considered in the present analysis. The sensor layer is used to sense the level of response of the composite structures. The sensed voltage is fed back to the actuator through the controller. In this study both displacement and velocity feedback controllers are employed to reduce the response of the composite laminate within acceptable limit. The Newmark direct time integration scheme is employed along with modal superposition method to improve the computational efficiency. It is observed from the numerical study that the laminated composite structures become weak in the presence of hygrothermal load. The response of the structure can be brought to the acceptable level once the AFC layer is activated through the feedback loop.

Damage assessment of composite structures using Particle Swarm Optimization

Jebieshia, T.R.,Maiti, D.K.,Maity, D. The Society for Aerospace System Engineering 2015 International Journal of Aerospace System Engineer Vol.2 No.2

Composite materials are highly sensitive to the presence of manufacturing and service-related defects that can reach a critical size during service condition and thereby may affect the safety of the structure. When the structure undergoes some kind of damage, its stiffness reduces, in turn the dynamic responses change. In order to avoid safety issues early detection of damage is necessary. The knowledge of the vibration behavior of a structure is necessary and can be used to determine the existence as well as the location and the extent of damage.

Frequency-Based Damage Assessment of Composite Members Using Unified Particle Swarm Optimization

T. R. Jebieshia,D. K. Maiti,D. Maity 한국항공우주학회 2020 International Journal of Aeronautical and Space Sc Vol.21 No.1

A numerical procedure is presented to detect and quantify damages in laminated composite beam and plate-like structures using unified particle swarm optimization (UPSO) technique. The presence of damage in any structure alters its integrity and performance (causes reduction in stiffness and strength) and thus changes the vibration response parameters such as frequency, mode shapes, damping ratio, and frequency response functions (FRFs). These changes in structural response parameters can be used for the identification of flaws in composite structures with the help of an optimization technique. For the present study, natural frequency is used as the diagnostic parameter and UPSO has been used as the optimization technique. An in-house Matlab code has been developed using finite element analysis (FEA) and has been used to extract the vibration responses of undamaged and damaged composite structures. Since composite materials are anisotropic in nature, effect of anisotropic damage on vibration characteristics of damaged composite structures is also presented. It is observed that the anisotropic damage exhibits strong orthogonality and in general, the occurrence of damage changes the vibration characteristics of the structure. It is also observed that as the damage intensity and damage area increase, there is considerable reduction occurring in the natural frequencies. The efficacy of the proposed methodology to identify damages is demonstrated using some numerically simulated composite beam and plate structures with single and multiple damages.

Forces and flow around three side-by-side square cylinders

Qinmin Zheng,Md. Mahbub Alam,S. Rehman,D.K. Maiti 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.1

A numerical investigation on forces and flow around three square cylinders in side-by-side arrangement is conducted at a Reynolds number Re = 150 with the cylinder center-to-center spacing ratio L/W = 1.1 ~ 9.0, where W is the cylinder side width. The flow at this Re is assumed to be two-dimensional, incompressible, and Newtonian. The flow simulation is conducted by using ANSYS-Fluent. The flow around the three side-by-side cylinders entails some novel flow physics, involving the interaction between the gap and free-stream side flows as well as that between the two gap flows. An increase in L/W from 1.1 to 9.0 leads to five distinct flow regimes, viz., base-bleed flow (L/W < 1.4), flip-flopping flow (1.4 < L/W < 2.1), symmetrically biased beat flow (2.1 < L/W < 2.6), non-biased beat flow (2.6 < L/W < 7.25) and weak interaction flow (7.25 < L/W < 9.0). The gap flow behaviors, time-averaged and fluctuating fluid forces, time-averaged pressure, recirculation bubble, formation length, and wake width in each flow regime are discussed in detail.