Manish Kumar Singh
@uconn.edu
Department of Materials Science and Engineering
University of Connecticut
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Manish Kumar Singh, Chanchal Ghosh, Benjamin Miller, and C. Barry Carter
Cambridge University Press (CUP)
Abstract Investigating the earliest stages of crystallization requires the transmission electron microscope (TEM) and is particularly challenging for materials which can be affected by the electron beam. Typically, when imaging at magnifications high enough to observe local crystallinity, the electron beam's current density must be high to produce adequate image contrast. Yet, minimizing the electron dose is necessary to reduce the changes caused by the beam. With the advent of a sensitive, high-speed, direct-detection camera for a TEM that is corrected for spherical aberration, it is possible to probe the early stages of crystallization at the atomic scale. High-quality images with low contrast can now be analyzed using new computing methods. In the present paper, this approach is illustrated for crystallization in a Ge2Sb2Te5 (GST-225) phase-change material which can undergo particularly rapid phase transformations and is sensitive to the electron beam. A thin (20 nm) film of GST-225 has been directly imaged in the TEM and the low-dose images processed using Python scripting to extract details of the nanoscale nuclei. Quantitative analysis of the processed images in a video sequence also allows the growth of such nuclei to be followed.
Chanchal Ghosh, Manish Kumar Singh, Shayani Parida, Matthew T. Janish, Arthur Dobley, Avinash M. Dongare, and C. Barry Carter
Springer Science and Business Media LLC
AbstractLi-ion batteries function by Li intercalating into and through the layered electrode materials. Intercalation is a solid-state interaction resulting in the formation of new phases. The new observations presented here reveal that at the nanoscale the intercalation mechanism is fundamentally different from the existing models and is actually driven by nonuniform phase distributions rather than the localized Li concentration: the lithiation process is a ‘distribution-dependent’ phenomena. Direct structure imaging of 2H and 1T dual-phase microstructures in lithiated MoS2 and WS2 along with the localized chemical segregation has been demonstrated in the current study. Li, a perennial challenge for the TEM, is detected and imaged using a low-dose, direct-electron detection camera on an aberration-corrected TEM and confirmed by image simulation. This study shows the presence of fully lithiated nanoscale domains of 2D host matrix in the vicinity of Li-lean regions. This confirms the nanoscale phase formation followed by Oswald ripening, where the less-stable smaller domains dissolves at the expense of the larger and more stable phases.
Vaibhav Pandey, Manish Kumar Singh, Joysurya Basu, K. Chattopadhyay, N.C. Santhi Srinivas, and Vakil Singh
Elsevier BV
Abstract Low cycle fatigue (LCF) behavior of the AA7075 was studied in the solution treated-ultrasonic shot peened and the peak aged (ST-USSP-PA) condition and was compared with that of the peak aged and ultrasonic shot peened (PA-USSP) as well the peak aged-ultrasonic shot peened and stress relieved (PA-USSP-SR) condition, studied earlier. LCF tests were carried out under fully reversed axial strain control at different total strain amplitudes (Δet/2) from ±0.38% to ±0.60%. LCF life was highest in the ST-USSP-PA followed by the PA-USSP and PA-USSP-SR conditions. It was found that nanostructure of comparable size (~22 nm) was developed up to a depth of ~50 μm in all the three conditions, however, there was much variation in the type, size, distribution and number density of the metastable of η precipitates in the three conditions. While the size of the strengthening precipitates η′ was ~20 nm in the ST-USSP-PA, it was much smaller (~10 nm) in the other two conditions. High resolution TEM examination revealed high density of dislocations in the matrix and also within the equilibrium η precipitates in the PA-USSP condition whereas dislocations were not observed in η precipitates of the PA-USSP-SR and ST-USSP-PA conditions. Highest fatigue life in the ST-USSP-PA condition is attributed to more homogeneous distribution, larger size and higher volume fraction of the strengthening precipitates η′ and consequent increase in the resistance against fatigue crack initiation.
Manish Kumar Singh, Chanchal Ghosh, Benjamin Miller, Paul G. Kotula, Shalini Tripathi, John Watt, Gokhan Bakan, Helena Silva, and C. Barry Carter
AIP Publishing
Ge2Sb2Te5 (GST-225) has been the most used active material in nonvolatile phase-change memory devices. Understanding the kinetics and dynamics involved in crystallization is critical for the optimization of materials and devices. A GST-225 thin film of 20 nm thickness was prepared by sputtering directly onto a Protochip and left uncapped and exposed to atmosphere for approximately 1 year. Early stages of crystallization and growth of the film have been studied inside the TEM from room temperature to 140 °C. The morphological and structural transformations have been studied by a Cs-corrected environmental TEM, and images have been recorded using a high-speed low electron dose camera (Gatan K3 IS). The amorphous to crystalline transformation has been observed at ∼35 °C. From the large field, high-resolution images obtained using the Gatan K3 IS camera early crystallization can be detected and nucleation rates and growth velocities can be obtained.
Laden Sherpa, Ajay Tripathi, Manish Singh, Rajiv Mandal, and Archana Tiwari
Springer Science and Business Media LLC
Nano-arsenic are synthesized using Bergenia ciliata root extracts in water from arsenic trioxide. The synthesized As nanoparticles, with an average diameter of 13(1) nm, self-assemble into nanotubules with average Feret diameter of 530(20) nm. These As nanotubules/nanoparticles have direct bandgap of 2.737 eV and incorporate multiple defect-related states within the gap. The presence of weak ferromagnetism in these nanotubules/nanoparticles are attributed to the dipolar interactions amongst the charges on the defect sites. Owing to van der Waals interactions between nanotubules and smaller nanoparticles, nanotubules present surface roughness and are utilized as surface-enhanced Raman spectroscopy substrate for probing methylene blue dye with an enhancement factor $$>10^3$$ > 10 3 .
Manish Kumar Singh, Shailendra Dwivedi, Suraj Singh Yadav, Rajesh Singh Yadav, and Sanjay Khattri
Springer Science and Business Media LLC
Chronic exposure to arsenic through drinking water and occupational exposure has been found to be associated with the diabetic symptoms. Earlier, we reported that arsenic induced enhanced oxidative stress, inflammation, dislipidemia and hepatotoxicity in mice have been protected by treatment with Emblica officinalis (amla). The present study has therefore been focused to investigate the efficacy of amla in mitigation of arsenic induced hyperglycemia in mice. Arsenic exposure (3 mg/kg b.w./day for 30 days) in mice altered glucose homeostasis and significantly decreases hepatic glucose regulatory enzyme, glucokinase (43%), glucose-6 phosphate dehydrogenase (38%), malic enzyme (60%) and significantly increases the level of glucose-6 phosphates (65%), phosphoenolpyruvate carboxykinase (43%), lactate, (59%) Na+ (6.8%) Cl− (10.4%), anion gap (13.9%) and pancreatic (IL-1β, TNF-α) inflammation markers (52%, 53%) as compared to controls. Arsenic exposure also significantly decreased serum insulin (44%) and c-peptide protein (38%) in mice as compared to controls. Co-administration of arsenic and amla (500 mg/kg b.w./day for 30 days) balanced blood sugar level, hepatic glucose regulatory enzyme (glucokinase, glucose-6 phosphate dehydrogenase, malic enzyme (68%, 37%, 45%) and significantly decreases glucose-6 phosphatase (25%), phosphoenolpyruvate carboxykinase (22%), blood ion concentration and also lactate, Na+, Cl− and anion gap (20%, 4.6%, 6.7%, 5.2%), pancreatic (IL-1β, TNF-α) inflammation marker (21%, 24%) and significantly increased the serum insulin (57%) and c-peptide protein (31%) as compared to those treated with arsenic alone. Results of the present study suggests that the hypoglycemic and antioxidant property of amla could be responsible for its protective efficacy in arsenic induced hyperglycemia.
Rajesh Rawat, Archana Tiwari, Manish Kumar Singh, R. K. Mandal, A. P. Pathak, and Ajay Tripathi
Informa UK Limited
In this work, we report the synthesis of Cu nanoparticles (NPs) by laser ablation technique using 532 nm and 1064 nm wavelength in ethylene glycol. The optical and morphological studies of as-prepared NP colloids were characterized using UV–Visible absorption , photoluminescence spectrometers and transmission electron microscope (TEM) techniques. Cu NPs synthesized at 532 nm and 1064 nm were spherical with an average size of nm and nm respectively. Furthermore, surface-enhanced Raman scattering (SERS) studies were performed on methylene blue (MB) using Cu NPs as SERS platform. In addition, the effects of size, shape and localized surface plasmon resonance (LSPR) of Cu NPs as well as the Raman excitation wavelength used for SERS measurement were investigated and discussed to give insight into the factors affecting their SERS enhancement factor.
Suresh Bandi, Devthade Vidyasagar, Shaik Adil, Manish Kumar Singh, Joysurya Basu, and Ajeet K. Srivastav
Elsevier BV
Abstract In this work, nanocrystalline tungsten oxide (WO3) powder was obtained by high energy ball milling (HEBM) followed by heat treatment of tungsten (W) powder. HEBM significantly influenced the oxidation behavior by reducing the crystallite size and inducing lattice strain in W powder. The resultant nanocrystalline WO3 shows variation in the optical bandgap with respect to the bulk counterparts. The alteration in the bandgap of WO3 is ascribed to the changes in crystallite size and the unit cell volume. In the end, a thorough correlation between fundamental interactions of these changes was succinctly highlighted.
Shalini Tripathi, Paul Kotula, Manish Kumar Singh, Chanchal Ghosh, Gokhan Bakan, Helena Silva, and C. Barry Carter
The Electrochemical Society
Manish Kumar Singh, Prajwal Chettri, Joysurya Basu, Ajay Tripathi, Bratindranath Mukherjee, Archana Tiwari, and R K Mandal
IOP Publishing
Vani Pawar, Manish Kumar, P. K. Dubey, Manish K. Singh, A. S. K. Sinha, and Prabhakar Singh
Springer Science and Business Media LLC
TiO2 samples with two different morphology were synthesized via sol–gel and hydrothermal techniques. The effect of synthesis procedure on structural, morphological, optical, and electrical properties was studied. Rietveld analysis revealed that anatase phase having tetragonal structure dominates at room temperature. The presence of anatse phase of TiO2 was further confirmed by the analysis of various peaks obtained from the Raman spectra. The field-emission scanning electron microscopy (FESEM) and transmission electron microscopy micrographs depicted the formation of two different kinds of morphologies with average particle size ranging from 9.87 to 11.35 nm. The FESEM micrographs showed homogeneous particle distribution for sol–gel synthesized sample, whereas it depicted rod-like structure in the sample synthesized via hydrothermal technique. The X-ray photoelectron spectroscopy analysis clearly indicated the presence of appropriate chemical composition and valency states of Ti and O element in TiO2 samples. The optical bandgap was estimated from the UV–visible spectra and found to be in corroboration with the reported values. The conductivity spectra were analyzed using Jonscher power law. The values of activation energy suggested that the conduction mechanism is thermally activated. The conductivity isotherms were scaled through Ghosh scaling model. In the sol–gel synthesized sample, the conduction mechanism was found to be independent of temperature in the entire measured temperature range; however, the hydrothermally synthesized sample depicted that the conduction mechanism is temperature-dependent in the measured temperature range. This discrepancy was understood in terms of structural changes and charge trapping within the structure.
Yagnesh Shadangi, Vikas Shivam, Manish Kumar Singh, Kausik Chattopadhyay, Joysurya Basu, and N.K. Mukhopadhyay
Elsevier BV
Abstract The influence of mechanical milling (MM), primarily on microstructure and phase evolution in Al62.5Cu25Fe12.5 (at%) quasicrystalline (IQC) matrix reinforced with varying volume fraction of Sn has been investigated by means of X-ray diffraction (XRD), scanning & transmission electron microscopy (SEM and TEM) and differential scanning calorimetry (DSC) methods. It was observed that with increasing the milling duration, the IQC phase transforms to crystalline B2 phase [Al (Cu, Fe) and Pm3 m, a = 0.29 nm]. In SEM and TEM analysis, it was found that both IQC and Sn particles are refined during MM. The XRD and TEM results confirm the formation nanostructured matrix consisting of nanocrystalline B2 phase along with minor IQC phase reinforced with ultrafine grained Sn particles after 40 h of MM. The STEM-EDS results show a homogenous distribution of elements (Al, Cu, Fe). The Sn particles were immiscible in a matrix consisting of B2 and IQC phase as indicated by XRD and TEM investigations.
Manish Kumar Singh, Prajwal Chettri, Joysurya Basu, Ajay Tripathi, Bratindranath Mukherjee, Archana Tiwari, and R.K. Mandal
Elsevier BV
Abstract Intermetallic phases in Au-Cu nanoparticles has been synthesized chemically in liquid phase. The heat-treatment of these nanoparticles at 180 °C for 1 h in solution phase led to the formation of Au-Cu alloy nanoparticles with nearly spherical shapes and monodispersed size of ∼10 nm. Subsequent heat-treatment at 300 °C for 30 min of these Au-Cu alloy nanoparticles not only revealed structural transformation to intermetallic phases (tetragonal AuCu (tP4) and cubic Cu3Au (cP4)) but also shape change occurs from spherical to rods having average aspect ratio ∼3.0. The structural determination at the particle has been carried out through nano-beam electron diffraction coupled with simulation of electron diffraction patterns and high resolution phase contrast images. These Au–Cu intermetallic nanoparticles exhibit an excellent surface enhanced Raman spectroscopic activity with methylene blue compared to that of Au-Cu alloy nanoparticles.
Manish Kumar Singh, Joysurya Basu, Bratindranath Mukherjee, and R.K. Mandal
Elsevier BV
Abstract Alloyed nanostructures of Au Cu in varying compositions were synthesized by wet chemistry routes. Synthetic products in all the compositions are FCC solid solutions of Au Cu with slightly varying lattice parameter. Variation in shape, size, and nature of attachment has been studied through electron microscopy and localized surface plasmon resonance measurements. FCC solid solutions upon heat-treatment at ~400 °C for 1 h under N2 atmosphere, transform to orthorhombic AuCu (oP8) and many superlattice structures based on it. Nano-beam electron diffraction reveals multiplication of periodicities along [3 1 ¯ 0], [210] and [201] directions, mostly originating due to the chemical or vacancy ordering. Symmetry breaking transitions of orthorhombic AuCu (oP8) from Pbam to P21212 has been observed. The phase with P21212 space group also shows polymorphic transition to P21221. All these transitions have been confirmed through nano-beam electron diffraction coupled with computed diffraction patterns based on Wyckoff positions. Commonly observed orthorhombic (oI40) AuCu upon heat-treatment has not been found. The multiplication of lattice periodicity along certain crystallographic directions, symmetry breaking transition and polymorphism in the same sub-group are important findings of this work. These might have far-reaching implications in electron transport properties of such nanostructures.
Pramod Kumar Singh, Manish Kumar Singh, Rajesh Singh Yadav, Rajendra Nath, Anju Mehrotra, Akash Rawat, and Rakesh Kumar Dixit
Informa UK Limited
Objectives: In view of the increasing risk of lead on human health, the present study has been carried out to investigate the neuroprotective effect of omega-3 fatty acid on chronic lead-induced neurotoxicity and behavioral impairment in rats. Methods: Different neurobehavioral parameters, biochemical assays, and histopathological analyses in brain regions of rats were conducted. Results: Rats exposed to different doses of lead (lead acetate 2.5, 5.0, 7.5 mg/kg body weight p.o. for 90 days) caused a significant decrease in body weight, brain weight, and behavioral changes as compared to controls. Abnormal histopathological and increased levels of lead in blood and brain regions increased the levels of ROS, LPO, PCC and decreased the levels of GSH with concomitant reduction in SOD, CAT, and GPx activities in the brain region of rats treated with different doses of lead as compared to controls. Co-treatment of lead with omega-3 fatty acid (500 mg/kg body weight p.o. for 90 days) decreased the levels of ROS, LPO, PCC, and increased the level of GSH, also increased SOD, CAT, and GPx activity and showed improvements in behavioral as well as histopathological changes as compared to lead-treated groups. Discussion: Our results proved that omega-3 fatty acid improved behavioral deficits, altered histopathological and oxidative stress in lead-intoxicated rats. Among three different doses, 2.5 mg/kg b.wt. of lead along with omega-3 fatty acid was the most preventive dose for the neurotoxicity. This work reveals the potential of omega-fatty acid as a protective drug for lead neurotoxicity.
Ajay S. Bangwal, Pardeep K. Jha, Pawan K. Dubey, Manish K. Singh, A. S. K. Sinha, Vasant Sathe, Priyanka A. Jha, and Prabhakar Singh
Royal Society of Chemistry (RSC)
The paradigm that chemical synthesis reduces the sintering temperature as compared to solid state synthesis seems to be violated in the case of the PrBaCo2O6−δ double perovskite.
Rajesh Kumar Kori, Manish Kumar Singh, Abhishek Kumar Jain, and Rajesh Singh Yadav
Springer Science and Business Media LLC
The problem of pesticides is not new and its exposure to human due to indiscriminate use is largely associated with the health related problems including neurotoxicological alterations. High levels of pesticide residues and their metabolites in the dietary constituents, food materials, maternal blood, cord blood, placenta breast milk have been reported and linked to alterations in birth weight, crown heel length, head circumference, mid-arm circumference and ponderal index of the neonates. Epidemiological studies have suggested that exposure of pesticide to human could be a significant risk factor for neurological disorders, including Parkinson’s disease, Alzheimer’s disease and multiple sclerosis. Cholinergic and non-cholinergic dysfunctions in pesticide exposed population, especially in children have also been frequently reported in recent years. Developmental neurotoxicity is another concern in the area where pregnant are more prone towards its exposure and which results in the abnormalities in the fetus. In view of the increasing risk of human health through pesticide exposure, the present review has been focused on the studies pertaining to pesticide induced neurochemical alterations and associated behavioral abnormalities in farm workers which could establish a possible link between the its exposure and associated health hazards.
Vikas Shivam, Joysurya Basu, Yagnesh Shadangi, Manish Kumar Singh, and N.K. Mukhopadhyay
Elsevier BV
Abstract An equiatomic AlCoCrFeNiMn hexanary high entropy alloy (HEA) was successfully synthesized by mechanical alloying. The 40 h milled powder exhibits chemical homogeneity with an average particle size of less than 3 μm. This alloy, after 40 h of milling produces a solid solution BCC phase (a = 2.89 ± 0.03 A), the lattice parameter of which is very close to the lattice parameter of Fe and Cr. Similar BCC solid solution phase is also obtained by following a two different milling schedule containing 3 elements i.e., AlCoCr & FeMnNi separately. Dynamic DSC thermogram of the hexanary alloy powder shows two exothermic peaks. The peak temperatures and heat evolution corresponding to each peak are sensitive to heating rates, indicating that the transformations are diffusional in nature. Phase evolution at these heat events was confirmed through high-temperature XRD and TEM study. It has been found that this alloy is stable upto 500 °C (773 K). Heat treatment at higher temperatures leads to the formation of a FCC phase closely related to Ni3Al type and Mn3Co7 type intermetallic phase. Microwave sintered samples show the similar kind of behaviour as in heat-treated powder. The BCC phase along with ordered Ni3Al type (L12) phase was observed in the bulk consolidated high entropy alloy. Thermo-physical properties of this alloy have been studied in order to elucidate its classification as high entropy alloy and to understand the essential differences with multicomponent glass forming alloys.
Manish Kumar Singh, Bratindranath Mukherjee, Joysurya Basu, and R. K. Mandal
Informa UK Limited
ABSTRACT We report the formation of new phases in bimetallic Au–Cu nanoparticles. These phases were observed in nanoparticle synthesised by adopting a three-step protocol in a single pot. Nanoparticles at 180°C for 1 h led to the formation of single-phase solid solution of Cu in Au. Subsequent heat treatment at 290°C for 2 h of these Au–Cu nanoparticles revealed three new phases. One of them relates to the modification of occupancy of Cu in an ordered AuCu tetragonal phase (tP4). This cell although retains tetragonal symmetry but displays metrical properties akin to that of a cube. The other two relates to vacancy ordering along <111> directions in the {111} planes of an ordered AuCu3 cubic phase (cP4). On the one hand, statistical occupancy of vacancy on Cu site in this cell leads to the reduction of cell size from ∼3.75 Å to ∼3.5 Å whereas ordering of vacant layer on the other hand gives rise to symmetry breaking. Former continues to display cubic symmetry whereas latter transforms to a trigonal cell.
Manish Kumar Singh, Ashish Kumar, and Rajiv Prakash
Elsevier BV
Abstract Present work has focused on the development of bio-organic hybrid materials based on hydrophobic DNA-complex incorporated in polymer and the study of charge transport properties across the junction formed by sandwiching it between conducting electrodes (called hetero-structured vertical diode). The inclusion of hydrophilic DNAs, both natural DNA and synthetic DNA (single strand DNA, ss-DNA and double strand DNA, ds-DNA), in organic semiconducting polymer specially regioregular poly (3, 3‴-didodecylquarterthiophene) (rr-PQT-12), have done in chloroform. Prior to DNAs inclusion, hydrophobic DNA-DDAB complexes have formed by reaction of hydrophilic DNA and didodecyldimethylammonium bromide, DDAB in aqueous solvent. Thereafter, as-mixed solution has been aged for 45 min to obtain fibrils' growth and used for the fabrication of devices. Various parameters including rectification ratio, ideality factor, saturation current, barrier height and device stability have been measured to study the nature of charge transport and effect of DNAs on the performance of devices. The device performance has been observed better with the incorporation of G-C rich DNAs. ds-DNA based devices exhibit improved rectification ratio i.e. two times higher than that of ss-DNA and three times higher than that of rr-PQT-12 with least turn-on voltage (0.56 V) or even low ideality factor (3.02), due to hot carrier injection phenomenon by assembled rr-PQT-12 to nearby nucleotide bases.
Nikhil Nikhil, Rajiv K. Pandey, Praveen Kumar Sahu, Manish Kumar Singh, and Rajiv Prakash
Royal Society of Chemistry (RSC)
Successful practical application of a polymer or its nanocomposite depends on the ability to produce a high performance electronic device at a significantly lesser cost and time than those needed to manufacture conventional devices.
Manish Kumar Singh, Prajwal Chettri, Ajay Tripathi, Archana Tiwari, Bratindranath Mukherjee, and R. K. Mandal
Royal Society of Chemistry (RSC)
We report single-phase syntheses of undoped 2H-MoS2 as well as Mn and Fe doped MoS2 by a facile hydrothermal route.
Manish Kumar Singh, Rajiv K. Pandey, and Rajiv Prakash
Elsevier BV
Abstract Solely inorganic semiconductors or their nanostructure based ultra violet photo detectors are still not up to the mark and remain unsatisfactory due to their inferior electrical performances. Therefore, the hybridization of inorganic semiconducting materials with organic semiconducting materials is emerging as one of the strategic methodology that has been recently implemented to augment the electrical performance like photocurrent, conductivity etc. Herein, we present a facile and efficient method for the hybridization of SnO2 nano wire with reduced grapheme oxide (rGO) nano sheet and subsequent investigation of enhancement in photocurrent of the hybrid material. Prior to the hybridization of SnO2 nanowire with rGO, SnO2 nanowire is synthesized via hydrothermal route, and contemporarily, rGO is synthesized via improved Hummers method followed by reduction using microwave. Further, as obtained hybrid material of SnO2/rGO is deposited over the Si/SiO2, glass and p-doped Si substrates via spray method by placing the mixture solution of SnO2/rGO hybrid, inside the medicine chamber of baby's spray nebulizer. The morphological properties have been discussed taking into account of atomic force microscopy (AFM), and scanning electron microscopy (SEM). The formation of nano-hybrid materials and structural properties of SnO2, rGO, and SnO2/rGO hybrid have been discussed based on X-ray diffraction (XRD), FTIR and UV–Vis spectroscopy. Further, the current-voltage (I-V) characteristics of as grown thin film of hybrid is conducted using cyclic voltammetry (CV) and AFM conducting tip. The metal-semiconductor- metal (MSM) structure is characterized in dark and in presence of light and found wavelength dependent photo detector property with drastic enhancement in photocurrent (102) at ±3 V for shorter wavelength as compare to longer wavelength. Thus, our material is selective for light source and can be used further for selective as well as short wavelength photo detector.
Manish Kumar Singh, Ashish Kumar, and Rajiv Prakash
Elsevier BV
Abstract The molecular ordering in organic polymer chains through π-π interactions is emerged to improve semiconductor performance. In the present work, long-range ordering of poly [2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2- b ]thiophene], pBTTT-C14 fiber is optimized in mixture of good and poor solvent (chloroform+toluene) blend using the concept of solvent driven self-assembly. Here, self-assembly is introduced by ageing followed by complete dissolution at elevated temperature in solvent-mixture. UV–visible spectroscopy demonstrated that the evidence of long range pBTTT-C14 fiber when experimentation is carried out in mixture of chloroform and toluene (9:1 v/v). However, in chloroform only, aggregation is slow while in toluene, aggregation is very fast under similar conditions. The fiber growth and its size are further verified by atomic force microscopy and HRTEM exemplified that the resultant aggregation of polymer chain in nanometric (diameter∼11 nm) range. Thereafter, the change in surface potential of fiber is studied by KPFM. This fibrous polymer is further sandwiched between ITO and Al-metal in order to study its junction behaviour. Fibrous pBTTT-C14 exhibits unsymmetrical charge transport properties over its isolated analogue with ∼9 times enhancement in mobility and ∼6.5 times enhancement in forward current density under the applied potential (−1.0 V to +1.0 V). This is owing to existence of a new charge transition path along the aggregation that consists of trapped charge between π-π stacking.
Suraj Singh Yadav, Manish Kumar Singh, Pawan Kumar Singh, and Vipin Kumar
Elsevier BV
Plants are the integral part of the traditional indigenous healthcare system and are becoming concrete source of new drug discovery, evident by the increasing numbers of modern drugs derived from the phytochemicals. Emblica officinalis Gaertn. or Phyllanthus emblica Linn (family Phyllanthaceae) has been explained extensively and well documented for its therapeutic efficacies in indigenous system of medicine, in India. Every part of this plant possesses high medicinal value but fruits are the most valuable part in folklore and therapeutic uses. The polyphenols found in E.officinalis, especially tannins and flavonoids are key responsible elements for major bioactivities. E.officinalis is one of the major component in various health tonics, also exerts synergistic effects in enhancing the medicinal efficacy. E.officinalis exhibits broad spectrum of pharmacological activities through various mode of actions including antioxidant, anticancer, immunomodulator, anti-inflammatory, cyto-protective properties etc. Medical practitioners across the globe also advocated its application in managing diabetes, dyslipidemia, obesity, several types of cancer, liver disorders, arthritis, gingivitis, wound healing etc. The present review analysed and summarized the pharmacological actions, experimental studies and clinical trials of E. officinalis with emphasis on its immuno-enhancer, antiinflammatory and anticancer activities and possible mechanism of actions to provide future directions in translating these findings clinically.