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Replacing aromatic π-system with cycloalkyl in triphenylamine dyes to impact intramolecular charge transfer in dyes pertaining to dye-sensitized solar cells application
No full textAbstract
In this study, five dyes comprising different donor moieties were proposed with a new
design approach. In the triphenylamine (TPA) moiety, the lone pair electrons on N takes part in resonance with three phenyl rings. As a result, the donating ability of TPA decreases in TPA-based dyes and hence the intramolecular charge transfer (ICT). We have proposed cycloalkyl moieties in place of phenyl moieties to stop the participation in the resonance of the lone pair with the other two phenyl rings so that the available
lone pair on N will be pumped towards acceptor to achieve efficient ICT. All dyes were subjected to density functional theory (DFT) and time-dependent DFT to evaluate their ground and excited-state properties. The projected density of state and natural bond orbital analyses were carried out to confirm the ICT from the donor to the acceptor moiety and also to comprehend the donating ability of the newly proposed donor
moieties. The reorganization energy of the dyes was calculated to find out the conformational changes that occurred during photoexcitation. The dyes were attached to (1 0 1) anatase surface of TiO2 to understand the electron transfer from the excited�Manuscript File Click here to view linked References
2state of the dye to the conduction band of TiO2. The adsorption energy of the dyes onto the (1 0 1) anatase surface of TiO2 was also evaluated. The absence of defect states in the density of states spectrum indicated the smooth electron transfer between dye/TiO2 interface
Multiobjective optimization of friction stir weldments of AA2014-T651 by teaching–learning-based optimization
No full textThis study focuses on optimization of process parameters, which may result in improved mechanical properties of the friction stir weldments of AA2014-T651. Plain taper and threaded taper cylindrical tool pin profiles were used for the study. A set of experiments was conducted at different levels of tool rotational and weld speeds using two tool pin profiles. Mechanical properties such as tensile strength, yield strength, impact strength, percentage of elongation, and hardness were measured. Objective functions are developed for the five mechanical properties in terms of input parameters. The input parameters were optimized using teaching–learning-based optimization algorithm technique to improve mechanical properties. The teaching–learning-based optimization algorithm suggested three best combinations such as combination-I (940 r/min and 32 mm/min), combination-II (1100 r/min and 40 mm/min), and combination-III (1205 r/min and 45 mm/min). The optimization is also validated with experimental result
Investigation of the effect of micro-fillers on Viscoelastic and Erosion wear Characteristics of PTFE composites
No full textPolytetrafluorethylene (PTFE)is one type of the most prominent semi�crystalline engineering thermo-plastics. The functional properties of PTFE are enhanced with the addition of micro-fillers in order to increase the utility of the composites. In the current work, three types of industrial Teflon composites with
micro-fillers viz. 25% by weight of glass fibers, 25% by weight of carbon fibers, and 25% by weight of graphite along with neat PTFE were used to investigate the viscoelastic and erosion wear characteristics. From the Dynamic Mechanical Analysis (DMA) graphs, it was observed that PTFE with 25% by weight of GF has
shown peak viscoelastic characteristics in three - point bending mode. The viscoelastic properties such as storage modulus of 1 GPa, loss modulus of 84 MPa and a tan of 0.137 respectively at 1400 C were observed from the DMA plots for the sample (PTFE+25%GF).Also, the erosion wear behavior of the same sample has shown good resistance at 1.5 bar and 90o impingement angle respectively due to the addition of glass fiber micro-filler
Critical Speed Analysis of Rotor Shafts Using Campbell Diagrams
No full textThe main aim of this paper is to avoid the critical speed at low rotational velocities for three different cases, i.e. shaft without rotor, single rotor system and two rotor system. The critical speeds of these rotor systems are analyzed with two boundary
conditions, viz. one end supported, both ends supported. Moreover, the rotors are mounted at two different positions: single rotor is placed at middle of the shaft and the
same rotor is split into two halves and kept at equal distance from the either end of shaft. This critical speed analysis is carried out on both solid and hollow shafts. The range of rotational speed for the analyses considered in between 0 to 5000 rpm. The critical speeds of various rotor systems are studied using Campbell diagram and it is observed that, the critical speeds are altered by changing the boundary conditions and replacing the solid shaft with hollow shaft of same torsional stiffness as well
Simulation Of Shank-Foot 2-Dof Manipulator With Computed Torque Control For Trajectory Generation
No full textExoskeletons and external assistive devices for human locomotion plays an predominant role in now a days. To assist elderly people and injured content, a shank foot manipulator is modelled and analysed. This shank foot manipulator is a 2 degree of freedom link which is represented by dynamic equation of non linear differential equation. Numerical solution is employed to obtain the closed form solutions. The trajectory generated by the manipulator is discussed with the control strategies like computed torque control with the use of MATLAB. Due to the uncertainties and non linearity nature, it becomes complex to attain the motion control in a accurate position. With the ease of computed torque control, the manipulator is made to be in a desired position
Rational design of SnO2 nanoflakes as a stable and high rate anode for lithium-ion batteries
No full textThe SnO2 nanofakes were prepared by simple one-step facile microwave-assisted solvothermal synthesis. The as-prepared
SnO2 nanofakes were systematically studied using X-ray difraction (XRD), feld emission scanning electron microscopy
(FE-SEM) and high-resolution transmission electron microscopy (HR-TEM). From FE-SEM images seen that SnO2 nanoparticles are stocked between the SnO2 nanofakes and also, pores are existed between the SnO2 fakes. TEM results reveal
that the SnO2 nanofakes were formed due to the self-assembly of very thin SnO2 nanosheets and also pores coexist between
the sheets. The prepared SnO2 nanofakes are used as an anode material for the fabrication of lithium-ion battery (LIB). The
SnO2 nanofakes electrode was found to show a stable reversible lithium storage capacity of 567 mA h g−1 even at a current
density of 500 mA g−1 after 50 cycles. The enhanced properties in terms of reversible capacity and cycle ability of the SnO2
nanofakes as an anode material are owing to its porous nature, which facilitates more lithium storage and interconnection
between the fakes and particles enhance the kinetic properties of the electrode material. Hence, the developed SnO2 nanofakes by simple one-step facile microwave-assisted solvothermal synthesis can be a stable and high rate anode material for
lithium-ion batterie
Critical Speed Analysis of Rotor Shafts Using Campbell Diagrams
Get PDFThe main aim of this paper is to avoid the critical speed at low rotational velocities for three different cases, i.e. shaft without rotor, single rotor system and two rotor system. The critical speeds of these rotor systems are analyzed with two boundary conditions, viz. one end supported, both ends supported. Moreover, the rotors are mounted at two different positions: single rotor is placed at middle of the shaft and the same rotor is split into two halves and kept at equal distance from the either end of shaft. This critical speed analysis is carried out on both solid and hollow shafts. The
range of rotational speed for the analyses considered in between 0 to 5000 rpm. The critical speeds of various rotor systems are studied using Campbell diagram and it is observed that, the critical speeds are altered by changing the boundary conditions and replacing the solid shaft with hollow shaft of same torsional stiffness as well
Synthesis, Characterization & Antimicrobial Activities of New Isoxazole Substituted Mannich and Schiff Bases of 5-Nitroisatin Analogs
Get PDFA sequence of new isoxazole substituted Schiff base and Mannich base of 5-nitroisatin are synthesized by a multi-step synthesis from 5-nitroisatin. Whole synthesized analogs were characterized using IR, NMR, Mass spectroscopy and microanalyses. All the Schiff and Mannich bases were tested for their antimicrobial potencies against some human pathogenic microorganism using agar well diffusion technique. The relationship between the biological activity and the functional group variation of the Schiff and Mannich bases were analyzed. Standard ciprofloxacin and ketoconazole were used to compare the antimicrobial activities of novel isatin coupled isoxazole derivatives
Environmentally sustainable rice husk ash reinforced cardanol based polybenzoxazine bio-composites for insulation applications
No full textAbstract
Tri-substituted cardanol based benzoxazine with functionalized rice husk ash (CBz/ FRHA) bio-composites were developed using renewable resource materials, and their thermal, electrical, and biological properties were studied by diferent analyti�cal methods. The molecular structure of CBz was confrmed by nuclear magnetic
resonance (1 H NMR) and Fourier transform infrared spectroscopy (FT-IR) tech�niques. Data resulted from thermal studies indicated that the incorporation of bio�based silica reinforcement efectively improved the thermal properties including Tg, thermal stability and char yield. Dielectric studies indicate that the bio-based com�posites possess the lower value of dielectric constant (low k—2.15) than that of neat matrix (low k—4.04). Further, the antimicrobial studies were carried out against Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae and Streptococcus bacte�ria using disk difusion method and the results obtained confrm that the CBz/FRHA bio-composites possess an improved antibacterial behavior. Data resulted from dif�ferent studies, and it is suggested that CBz/FRHA based bio-composites can be used
as cost competitive materials in the form of adhesives, sealants, encapsulants and matrices for low-k insulation application in the feld of microelectronics for high�performance application
Polypropylene/phosphazene nanotube nanocomposites: Thermal, mechanical, and flame retardation studies
No full textAbstract
In this study, flame retardant polypropylene (PP) nanocomposites with supe�rior mechanical performance have been developed using amine-functionalized phosphazene nanotubes (APZS, 1–10 wt%) through melt-blending method.
Polypropylene-graft-maleic anhydride was used as the compatibilizer to attain effective interaction between the nanofiller and the PP matrix. The characteri�zation of amine-functionalized phosphazene nanotubes (APZS) using solid�state nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy, X-ray diffraction, fourier-transform infrared (FTIR), and transmission electron microscopy indicated successful amine functionalization, though structural changes were observed as compared to the unfunctionalized nanotubes. Owing to the covalent polymer-filler interfacial interactions and resulting in uniform filler dispersion, the nanocomposites exhibited significant enhancement in the tensile modulus up to 5 wt% APZS content (98% increment at 5 wt% content as
compared to pure polymer). The addition of a small fraction of APZS (1 wt%) improved the impact strength of the nanocomposite by more than 180%. APZS acted as a weak nucleating agent for PP, thereby leading to enhanced degree of
crystallinity (up to 5 wt% APZS content). The thermal stability of the nanocomposites was also enhanced with APZS content. The nanocomposites with 5 and 10 wt% APZS loading exhibited a V0 rating in UL-94 test, indicating that APZS introduced a robust flame retardancy behavior in the PP nanocomposites. The limiting oxygen index values also confirmed the findings
from the UL-94 analysis. The developed nanocomposites exhibit high potential of use in a wide range of high temperature application