Filling Single Wall Carbon Nanotubes with Metal Chloride and Metal Nanowires and Imaging with Scanning Transmission Electron Microscopy

Nanowires of magnetic metals (Ho, Gd) have been synthesized inside the hollow interior of single wall carbon nanotubes by the sealed-tube reaction. Amongst the d- and f-series metal chlorides investigated in this study, HoCl3 and GdCl3 fill the SWNTs to a significantly higher extent than FeCl2 and CoCl2. HoCl3 and GdCl3 nanowires have been transformed into the respective metal nanowires via the reduction of the chloride nanowires. The nanowires have been imaged using high-resolution transmission electron microscopy and scanning transmission electron microscopy (STEM). X-ray energy dispersive spectroscopy carried out in conjunction with STEM confirmed the presence of metal chloride and metal nanowires

Structure and properties of C\u3csub\u3e60\u3c/sub\u3e@SWNT

Our recent achievement of high-yield C60@SWNT synthesis facilitates characterization by various techniques, including selected area electron diffraction (SAD) and Raman spectroscopy. The obtained SAD patterns show that interior C60 molecules sit on a simple 1-D lattice having a parameter of 1.00 nm. Simulated SAD patterns and real-space measurements both support this determination and do not indicate a lattice with a more complex basis, e.g. a dimer basis. Empty and bulk-filled SWNTs (22%, 56%, and 90% yields), each subjected to identical processing steps, were examined by room temperature Raman spectroscopy. Systematic differences are seen between the spectra of filled and unfilled SWNTs, particularly with respect to the G- and RBM-bands of the nanotubes. We present a possible explanation for this behavior

Reproducible synthesis of C\u3csub\u3e60\u3c/sub\u3e@SWNT in 90% yields

In previous works, we have shown our discovery of C60@SWNT and first described the general mechanism of filling, which involves the vapor phase transport of C60 molecules to openings in the SWNTs\u27 walls. Here, we discuss the high-yield synthesis of C60@SWNT by refinements to our method. Yields are measured by a calibrated weight uptake technique, a methodology that is not subject to many of the potential pitfalls inherent to other techniques that have been applied. At certain processing conditions, yields exceeding 90% were obtained and corroborated by transmission electron microscopy. From our data, we determine the parameters most important for creating endohedral SWNT supramolecular assemblies by the vapor phase method. Our results pave the way for successful single-tube measurements and for high-yield filling with non-fullerenes

Processing of single wall carbon nanotubes and implications for filling experiments

Single wall carbon nanotubes (SWNTs) have been processed in different schemes to get clean material for use in various filling experiments. The SWNTs synthesized by different methods require different processing schemes, and this is presumably due to heterogeneous nature of the various contaminants present along with the carbon nanotubes. For the pulsed laser synthesized SWNTs, a combination of nitric acid, hydrogen peroxide and hydrochloric acid treatment gives best results and the purified SWNTs give best ever filling fraction for fullerene, C60 of ~90%. The processing improves the surface cleanliness of SWNTs, in turn giving greater access for the target molecules, and hence the higher filling fraction. For the carbon arc produced SWNTs, air oxidation followed by treatment with nitric acid has been found to work best and the processed SWNTs have been used for filling experiments with metal chlorides. Both these processing schemes still leave a small fraction of catalyst impurities in the final material, thus the material quality of filled material and hence its properties depend on the processed material used for the filling experiments

Graphene-Based Nanocomposites for Energy Storage

Since the first report of using micromechanical cleavage method to produce graphene sheets in 2004, graphene/graphene-based nanocomposites have attracted wide attention both for fundamental aspects as well as applications in advanced energy storage and conversion systems. In comparison to other materials, graphene-based nanostructured materials have unique 2D structure, high electronic mobility, exceptional electronic and thermal conductivities, excellent optical transmittance, good mechanical strength, and ultrahigh surface area. Therefore, they are considered as attractive materials for hydrogen (H2) storage and high-performance electrochemical energy storage devices, such as supercapacitors, rechargeable lithium (Li)-ion batteries, Li–sulfur batteries, Li–air batteries, sodium (Na)-ion batteries, Na–air batteries, zinc (Zn)–air batteries, and vanadium redox flow batteries (VRFB), etc., as they can improve the efficiency, capacity, gravimetric energy/power densities, and cycle life of these energy storage devices. In this article, recent progress reported on the synthesis and fabrication of graphene nanocomposite materials for applications in these aforementioned various energy storage systems is reviewed. Importantly, the prospects and future challenges in both scalable manufacturing and more energy storage-related applications are discussed

A study of lipid profile in patients with subclinical hypothyroidism: A tertiary care hospital study

Background: Dyslipidemia is thought to confer risk of cardiovascular disease development. Overt hypothyroidism is associated with lipid abnormalities. However, the relationship between subclinical hypothyroidism (SCH) and pattern of lipid abnormalities is unclear. The aim of this study was to assess lipid abnormalities in patients of subclinical hypothyroidism (SCH) and investigate relationship between lipid level and TSH. Methods: Serum lipid levels of 100 patients with subclinical hypothyroidism (SCH) and 100 age and sex matched euthyroid controls were evaluated in this cross sectional case control study. Results: In this study total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) were significantly elevated (p value<0.05) in patients with subclinical hypothyroidism (SCH) as compared to control group. Triglycerides (TG) and very low density lipoprotein cholesterol (VLDL-C) were also high in these patients as compared to control but the difference was not statistically significant. High density lipoprotein cholesterol (HDL-C) was marginally lower in these patients than control. Conclusion: Total cholesterol (TC) and low density lipoprotein (LDL-C) are higher in patients with subclinical hypothyroidism (SCH) as compared to euthyroid individuals. Other lipid like Triglycerides (TG) and very low density lipoprotein cholesterol (VLDL-C) may be marginally elevated whereas high density lipoprotein cholesterol (HDL-C) may be slightly reduced in these patients as compared to euthyroid individuals. There is also a positive correlation of LDL-C and TC with TSH level. As abnormal lipids are associated with development of cardiovascular diseases, lipid profile in these patients needs careful monitoring

Study of Epidemiological Characteristics of the SARS-CoV-2 Pandemic in Hassan District, Karnataka,India

Background and Objective: In late December 2019, a novel corona virus (SARS-CoV-2) emerged in China and rapidly spread globally including India. Data on epidemiology of COVID 19 was limited during initial periods of outbreak in India. This study describes the epidemiological characteristics of COVID-19 patients in a District of South India.Methods: This prospective ,observational study included patients fulfillingWHO case definition of COVID-19 and confirmed to have SARS-CoV-2 infection by reverse transcription- polymerase chain reaction(RT-PCR) admitted between May, 2020 and July 2020.The demographic and epidemiological data was collected and analyzed.Results: Out of 1376 patients were admitted, the age group most affected was 31-40 years and 62% were male,73.69% were asymptomatic. Fever( 46.4%) ,cough (38.95%) and dyspnea (22.92% ) the most common presentation. 88.51% of the patients didn’t have any comorbidities. Diabetes Mellitus was the most common comorbidity.21.72% had history of travel with a positive case.Conclusion: This study revealed ,COVID 19 affecting younger age, males ,majority being asymptomatic and Diabetes Mellitus to be the major comorbidity

Nanomechanical resonance studies of carbon nanotube peapod bundles

Filled carbon nanotubes represent a class of tunable nanoscale materials that could provide both high-quality resonance and sensing specificity for nanoresonator-based devices. We have studied the mechanical properties of C60-filled single-walled carbon nanotube bundles through observation of their mechanical resonances in a transmission electron microscope. X-ray diffraction was used to qualitatively study the filling of C60 in the bulk material. Electron diffraction was used to confirm the filling of each bundle prior to the measurement of individual mechanical resonance frequencies. The electron-diffraction pattern revealed a C60 spacing periodicity of 9.97 \uc5 within the lumen of the nanotubes, which is close to the theoretical equilibrium spacing of R0 = 10.05\u2004\uc5 in bulk C60. An average ratio of (Eb/\u3c1)1/2 = 13\u2009230\ub13187\u2004m/s was observed for the unfilled bundles, compared with a ratio of (Eb/\u3c1)1/2 = 19\u2009002\ub12307\u2004m/s for C60-filled bundles. Such values indicate an increase of the average bending modulus by as much as 170% in C60-filled bundles. A dependence of this ratio on the diameter of the structures was also observed. This dependence is explained by the increased importance of intertube slipping in bundles of larger diameter.Peer reviewed: YesNRC publication: N