Evaluations of Thermal and Antibacterial Properties of Nanocomposites of Functionalized Poly(methyl methacrylate) with Different Amino Containing Groups

Hari Madhav,Paramjit Singh,Neetika Singh,Gautam Jaiswar 한국고분자학회 2017 Macromolecular Research Vol.25 No.7

The main object of this study is to analyse the effects of different functional groups on the thermal and microbial properties of nanocomposites of poly(methyl methacrylate) (PMMA). For this, amino functionalized PMMA were synthesized by using post polymer functionalization method. In this method, PMMA was treated with four different amino compounds to obtain functionalized PMMA. To determine the structural features, functionalized PMMA was characterized with Fourier transform infrared (FTIR) spectroscopy. These functionalized PMMA were used to prepare functionalized polymer nanocomposites with addition of nanoclay and Ag nanoparticles into the polymer matrix. These nanocomposites were further studied against thermal and antibacterial properties. Sophisticated analytical techniques i.e., thermal gravimetric analysis (TGA), differential thermal analysis (DTA), and derivative thermogravimetric curve (DTG) were used to characterize the thermal properties of nanocomposites. Antibacterial study was performed by using disc diffusion method against bacteria E. coli. The thermal results showed that, the maximum degradation temperature (Td) increases up to 85.5oC in air atmosphere in case of sample HM2. Antibacterial study showed that, the bacteria have least effect on the silver containing functionalized polymer nanocomposites.

Hydrogen-Atom Abstraction Reaction of CF₃CH₂OCF₃ by Hydroxyl Radical

Singh, Hari Ji,Mishra, Bhupesh Kumar,Rao, Pradeep Kumar Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.12

Theoretical investigations are carried out on the title reaction by means of ab-initio and DFT methods. The optimized geometries, frequencies and minimum energy path are obtained at UB3LYP/6-311G(d,p) level. Single point energy calculations are performed at MP2 and MP4 levels of theory. Energetics are further refined by calculating the energy of the species with a modified Gaussian-2 method, G2M(CC,MP2). The rate constant of the reaction is calculated using Canonical Transition State Theory (CTST) utilizing the ab-initio data obtained during the present study and is found to be $5.47{\times}10^{-12}\;cm^3\;molecule^{-1}s^{-1}$ at 298 K and 1 atm.

Ab Initio Study on the Thermal Decomposition of CH3CF2O Radical

Hari Ji Singh,Bhupesh Kumar Mishra,Nand Kishor Gour 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.12

The decomposition reaction mechanism of CH3CF2O radical formed from hydroflurocarbon, CH3CHF2 (HFC- 152a) in the atmosphere has been investigated using ab-initio quantum mechanical methods. The geometries of the reactant, products and transition states involved in the decomposition pathways have been optimized and characterized at DFT-B3LYP and MP2 levels of theories using 6-311++G(d,p) basis set. Calculations have been carried out to observe the effect of basis sets on the optimized geometries of species involved. Single point energy calculations have been performed at QCISD(T) and CCSD(T) level of theories. Out of the two prominent decomposition channels considered viz., C-C bond scission and F-elimination, C-C bond scission is found to be the dominant path involving a barrier height of 12.3 kcal/mol whereas the F-elimination path involves that of a 28.0 kcal/mol. Using transition-state theory, rate constant for the most dominant decomposition pathway viz., C-C bond scission is calculated at 298 K and found to be 1.3 × 104 s-1. Transition states are searched on the potential energy surfaces involving both decomposition channels and each of the transition states are characterized. The existence of transition states on the corresponding potential energy surface are ascertained by performing Intrinsic Reaction Coordinate (IRC) calculation.

Computational Study on OH and Cl Initiated Oxidation of 2,2,2-Trifluoroethyl Trifluoroacetate (CF3C(O)OCH2CF3)

Hari Ji Singh,Laxmi Tiwari,Pradeep Kumar Rao 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.5

Hydrofluoroethers (HFEs) are developed as a suitable for the replacement of environmentally hazardous CFCs and are termed as third generation refrigerants. One of the major products of decomposition of HFEs in the atmosphere is a fluoroester. The present study relates to the OH and Cl initiated oxidation of CF3C(O)OCH2CF3 formed from the oxidation of HFE-356mff. The latter is used as a solvent in the industry and reaches the atmosphere without any degradation. Kinetics of the titled molecule has been studied at MPWB1K/6- 31+G(d,p) level of theory. Single point energy calculations have been made at G2(MP2) level of theory and barrier heights are determined. The rate constants are calculated using canonical transition state theory. Tunnelling correction are made using one-dimensional Eckart potential barrier. The rate constant calculated during the present study are compared with the experimental values determined using relative rate method and FTIR detection technique.

Ab Initio Study on the Thermal Decomposition of CH₃CF₂O Radical

Singh, Hari Ji,Mishra, Bhupesh Kumar,Gour, Nand Kishor Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.12

The decomposition reaction mechanism of $CH_3CF_2O$ radical formed from hydroflurocarbon, $CH_3CHF_2$ (HFC-152a) in the atmosphere has been investigated using ab-initio quantum mechanical methods. The geometries of the reactant, products and transition states involved in the decomposition pathways have been optimized and characterized at DFT-B3LYP and MP2 levels of theories using 6-311++G(d,p) basis set. Calculations have been carried out to observe the effect of basis sets on the optimized geometries of species involved. Single point energy calculations have been performed at QCISD(T) and CCSD(T) level of theories. Out of the two prominent decomposition channels considered viz., C-C bond scission and F-elimination, C-C bond scission is found to be the dominant path involving a barrier height of 12.3 kcal/mol whereas the F-elimination path involves that of a 28.0 kcal/mol. Using transition-state theory, rate constant for the most dominant decomposition pathway viz., C-C bond scission is calculated at 298 K and found to be 1.3 ${\times}$ 10$^4s{-1}$. Transition states are searched on the potential energy surfaces involving both decomposition channels and each of the transition states are characterized. The existence of transition states on the corresponding potential energy surface are ascertained by performing Intrinsic Reaction Coordinate (IRC) calculation.

Computational Study on OH and Cl Initiated Oxidation of 2,2,2-Trifluoroethyl Trifluoroacetate (CF₃C(O)OCH₂CF₃)

Singh, Hari Ji,Tiwari, Laxmi,Rao, Pradeep Kumar Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.5

Hydrofluoroethers (HFEs) are developed as a suitable for the replacement of environmentally hazardous CFCs and are termed as third generation refrigerants. One of the major products of decomposition of HFEs in the atmosphere is a fluoroester. The present study relates to the OH and Cl initiated oxidation of $CF_3C(O)OCH_2CF_3$ formed from the oxidation of HFE-356mff. The latter is used as a solvent in the industry and reaches the atmosphere without any degradation. Kinetics of the titled molecule has been studied at MPWB1K/6-31+G(d,p) level of theory. Single point energy calculations have been made at G2(MP2) level of theory and barrier heights are determined. The rate constants are calculated using canonical transition state theory. Tunnelling correction are made using one-dimensional Eckart potential barrier. The rate constant calculated during the present study are compared with the experimental values determined using relative rate method and FTIR detection technique.

Atlanto-occipital assimilation: embryological basis and its clinical significance

Hari Hara Hanusun N,Akanksha Singh,Pooja Poddar,Jessy J P,Neerja Rani,Hitesh Gurjar,Seema Singh 대한해부학회 2024 Anatomy & Cell Biology Vol.57 No.1

Atlanto-occipital assimilation is an osseous embryological anomaly of the craniovertebral junction in which the atlas (C1) is fused to the occiput of skull. Embryologically, this assimilation may happen due to failure of the segmentation and separation of the caudal occipital and the cranial cervical sclerotome. The segmentation clock is maintained by NOTCH and WNT signalling pathways along with Hox genes and retinoic acid. This condition is likely to be a consequence of mutation in above mentioned genes. The knowledge of this assimilation may be crucial for the clinicians as it may lead to various neurovascular symptoms. The present case report involves the analysis of atlanto-occipital assimilation with its clinical significance and embryological basis.

Hydrogen-Atom Abstraction Reaction of CF3CH2OCF3 by Hydroxyl Radical

Hari Ji Singh,Bhupesh Kumar Mishra,Pradeep Kumar Rao 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.12

Theoretical investigations are carried out on the title reaction by means of ab-initio and DFT methods. The optimized geometries, frequencies and minimum energy path are obtained at UB3LYP/6-311G(d,p) level. Single point energy calculations are performed at MP2 and MP4 levels of theory. Energetics are further refined by calculating the energy of the species with a modified Gaussian-2 method, G2M(CC,MP2). The rate constant of the reaction is calculated using Canonical Transition State Theory (CTST) utilizing the ab-initio data obtained during the present study and is found to be 5.47 × 10‒12 cm3 molecule‒1s‒1 at 298 K and 1 atm.

Atomically Thin-Layered Molybdenum Disulfide (MoS₂) for Bulk-Heterojunction Solar Cells

Singh, Eric,Kim, Ki Seok,Yeom, Geun Young,Nalwa, Hari Singh American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.4

<P>Transition metal dichalcogenides (TMDs) are becoming significant because of their interesting semiconducting and photonic properties. In particular, TMDs such as molybdenum disulfide (MoS2), molybdenum diselenide (MoSe2), tungsten disulfide (WS2), tungsten diselenide (WSe2), titanium disulfide (TiS2), tantalum sulfide (TaS2), and niobium selenide (NbSe2) are increasingly attracting attention for their applications in solar cell devices. In this review, we give a brief introduction to TMDs with a focus on MoS2; and thereafter, emphasize the role of atomically thin MoS2 layers in fabricating solar cell devices, including bulk-heterojunction, organic, and perovskites-based solar cells. Layered MoS2 has been used as the hole-transport layer (HTL), electron-transport layer (ETL), interfacial layer, and protective layer in fabricating heterojunction solar cells. The trilayer graphene/MoS2/n-Si solar cell devices exhibit a power-conversion efficiency of 11.1%. The effects of plasma and chemical doping on the photovoltaic performance of MoS2 solar cells have been analyzed. After doping and electrical gating, a power-conversion efficiency (PCE) of 9.03% has been observed for the MoS2/h-BN/GaAs heterostructure solar cells. The MoSrcontaining perovskites-based solar cells show a PCE as high as 13.3%. The PCE of MoS2-based organic solar cells exceeds 8.40%. The stability of MoS2 solar cells measured under ambient conditions and light illumination has been discussed. The MoS2-based materials show a great potential for solar cell devices along with high PCE; however, in this connection, their long-term environmental stability is also of equal importance for commercial applications.</P>

Cyber Threat Intelligence Traffic Through Black Widow Optimisation by Applying RNN-BiLSTM Recognition Model

Kanti Singh Sangher,Archana Singh,Hari Mohan Pandey International Journal of Computer ScienceNetwork S 2023 International journal of computer science and netw Vol.23 No.11

The darknet is frequently referred to as the hub of illicit online activity. In order to keep track of real-time applications and activities taking place on Darknet, traffic on that network must be analysed. It is without a doubt important to recognise network traffic tied to an unused Internet address in order to spot and investigate malicious online activity. Any observed network traffic is the result of mis-configuration from faked source addresses and another methods that monitor the unused space address because there are no genuine devices or hosts in an unused address block. Digital systems can now detect and identify darknet activity on their own thanks to recent advances in artificial intelligence. In this paper, offer a generalised method for deep learning-based detection and classification of darknet traffic. Furthermore, analyse a cutting-edge complicated dataset that contains a lot of information about darknet traffic. Next, examine various feature selection strategies to choose a best attribute for detecting and classifying darknet traffic. For the purpose of identifying threats using network properties acquired from darknet traffic, devised a hybrid deep learning (DL) approach that combines Recurrent Neural Network (RNN) and Bidirectional LSTM (BiLSTM). This probing technique can tell malicious traffic from legitimate traffic. The results show that the suggested strategy works better than the existing ways by producing the highest level of accuracy for categorising darknet traffic using the Black widow optimization algorithm as a feature selection approach and RNN-BiLSTM as a recognition model.