[Show abstract][Hide abstract] ABSTRACT: Two methods have been attempted to intercalate an anionic anticancerous drug methotrexate (MTX) into Mg-Al layered double hydroxide (LDH): a) anion exchange method (sample A′) and b) in situ coprecipitation method followed by a soft hydrothermal treatment (sample A″) to form a biohybrid material. Both the materials obtained were characterized by powdered sample X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), thermogravimetric-differential thermal analysis (TG-DTA), particle size distribution (PSD) analysis and field emission scanning electron microscopy (FE-SEM). High performance liquid chromatography (HPLC) was used to determine the integrity of the MTX and to quantify the drug loading in the materials. HPLC data of sample A′ confirms the integrity of the MTX moiety in the interlayer space of Mg-Al-LDH which has been further verified by XRD and FTIR spectroscopy and drug loading in the hybrid system was found to be 20.22 mg.g−1. However, the HPLC data of sample A″ supports that under soft hydrothermal condition decomposition of MTX is operating and the major decomposition product was identified as N10-methyl folic acid that remains adsorbed on Mg-Al-LDH surface, primarily, as indicated by the TG-DTA study.
Transactions - Indian Ceramic Society 01/2015; 69(4):229-234. DOI:10.1080/0371750X.2010.11090840 · 0.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Microwave and conventional heat treatment processes were utilized to achieve adequate crystallization in MgO-Al2O3-TiO2 based glass coatings with identical compositions. The processed coatings were evaluated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and image analysis. XRD analysis showed that the misfit strain in the lattice of conventionally heat treated coating was higher than that in the corresponding microwave processed coating. SEM investigation along with image analysis confirmed that microwave heating generated finer crystallites in the glass coating than those obtained in the coating processed by conventional heating.
Transactions - Indian Ceramic Society 01/2015; 67(3):139-146. DOI:10.1080/0371750X.2008.11078650 · 0.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper, the hydrogen and hydrogen-methane mixed plasma have been generated inside a 33 cm diameter quartz bell jar with a low power (9 KW) and lower frequency 915 MHz microwave plasma chemical vapor deposition system. The reactor is being used for growing polycrystalline diamond (PCD) over large area (100 mm). The generated plasma is diagnosed by in situ optical emission spectroscopy method with wave length ranging from 200 to 900 nm. The effects of microwave power, chamber pressure and gas concentration on plasma characteristics have been studied in this work. Within the optical range, Balmer Hα
, C2swan band and CH lines have been detected at the wavelengths of 655.95, 485.7, 515.82 and 430.17 nm, respectively. It has been observed that for hydrogen plasma, the amount of transition from hydrogen atom inner shell 3 to 2 (Hα
) is almost constant with increasing microwave (MW) power (from 2000 to 2800 W) and pressure (from 15 to 30 Torr) initially, after that it increases with further increase of MW power and pressure, whereas, the transition from 4 to 2 (Hβ
) is slowly increased with increasing MW power and pressure. For hydrogen-methane plasma, intensities of C2 swan band, i.e., the transitions from D3πg
energy levels, are also increased with the increasing microwave power and reactor pressure. It has been observed that the radicals present in the plasma are affected by variation of different reactor parameters like pressure, MW power, CH4 concentration, etc.
[Show abstract][Hide abstract] ABSTRACT: The effect of incorporating yttria stabilized zirconia on fracture toughness and other related mechanical properties of high alumina ceramics was studied. The experiments were so designed as to allow study of the effect of sintering at various temperatures with different periods of soaking on some of the properties. It was shown that the transverse rupture strength and fracture toughness were largely dependent on the percentage and crystalline phases of ZrO2 present and also on the sintering temperature.
Transactions - Indian Ceramic Society 05/2014; 48(4):68-75. DOI:10.1080/0371750X.1989.10822949 · 0.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The effect of method of powder preparation on the mechanical properties of partially stabilized zirconia has been studied. Zirconia powder doped with 3 mol% of yttria was prepared by three different methods, viz. mechanical method, modified mechanical method and co-precipitation method. It has been observed that fracture toughness, transverse rupture strength, microhardness etc improved with the improvement in the powder preparation method.
Transactions - Indian Ceramic Society 05/2014; 48(6):111-114. DOI:10.1080/0371750X.1989.10822960 · 0.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The effect of incorporating ZrO2 and TiC on different mechanical properties as well as the performance of alumina based ceramic cutting tools has been studied. Along with the mechanical properties of the tool materials, the importance of tool geometry and the effect of different cutting parameters, viz. cutting speed, feed and depth of cut, on the tool life have also been discussed. It was observed that these tools were useable successfully even at a cutting speed of 350 m/min and up to that limit, the increase in cutting speed had a slightly negative effect on their performances while the wear rate was found to be more sensitive to the variation of depth of cut. Addition of TiC and ZrO2 improved their performances for the applications requiring very high speed and high depth of cut respectively.
Transactions - Indian Ceramic Society 05/2014; 49(3):60-66. DOI:10.1080/0371750X.1990.10822993 · 0.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In recent years polycrystalline alumina ceramics have been widely used as bioceramic implants in various orthopaedic applications in western countries. Alumina ceramics have been proved to be more biocompatible, resistant to corrosion and abrasion over conventional metals and, therefore, higher durability of the implants is envisaged. The present paper deals with the development of ceramic heads for hemi-hip prosthesis implants which have been implanted to 18 different human patients. Physical and mechanical characteristics and biocompatibility of these ceramic heads have been examined in short term clinical studies. The study revealed no abnormal clinical effect on the patients after 2 years of implantation.
Transactions - Indian Ceramic Society 03/2014; 53(5):123-126. DOI:10.1080/0371750X.1994.10804655 · 0.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Yttria—partially stabilized zirconia (Y—PSZ) ceramics containing 3.5, 4.0 and 5.0 mol% Y2O3 were fabricated from commercial grade zirconia powder by dry pressing and normal sintering at 1600°C. The mechanical properties and microstructures of such materials were examined. Mechanical properties, both strength and fracture toughness, deteriorated with increasing yttria content. XRD revealed the presence of both tetragonal and monoclinic phases in the sintered materials and with decreasing yttria content, the tetragonal phase increased. Vickers' microhardness values differed slightly among the three compositions.
Transactions - Indian Ceramic Society 03/2014; 51(3):60-62. DOI:10.1080/0371750X.1992.10804536 · 0.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Polycrystalline diamond (PCD) films have been grown over 100 mm diameter silicon (100) substrate, using microwave plasma chemical vapour deposition (MPCVD) technique. The deposition was carried out inside a 15 cm diameter quartz chamber with microwave power of 15 kW at 915 MHz frequency. Uniform substrate surface temperature of 1050°C with plasma heating was maintained with simultaneous cooling arrangement. The pressure was 110 Torr and the microwave incident power was 8.5 kW. Temperature uniformity and plasma geometry over the substrate are the key parameters for producing uniformly thick MPCVD diamond films of high quality. Thickness uniformity of as-deposited films is ±10% across 100 mm diameters with a growth rate of 1 µm.h–1. The grown PCD was characterized by X-ray diffractometry (XRD), Raman spectrometry, field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and bright field imaging technique. Experimental results indicate columnar growth of a very densely crystalline PCD with (111) facets of high quality morphology.
Transactions - Indian Ceramic Society 12/2013; 72(4):225-232. DOI:10.1080/0371750X.2013.870768 · 0.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Freestanding polycrystalline diamond (PCD) coatings are of immense technological importance. PCD has been grown over silicon substrates by microwave plasma assisted chemical vapor deposition (MWPACVD) process. The coatings are grown by suitable optimisation of the growth parameters of a 915 MHz microwave reactor. Thereafter, 1:1:1 solution of hydrofluoric acid (HF), nitric acid (HNO3) and acetic acid (CH3COOH) is used to etch out the silicon wafer from the backside of the coating. Hereby, freshly generated nucleation surface, could be characterised by scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy and stylus profilometer and could be compared with the growth side. It is found that both the nucleation side and growth side are of very high quality (full width at half maxima, i.e., FWHM < 8 cm-1). The growth side is (111) textured, whereas, the nucleation side is very smooth with embedded detonation-nano-diamond (DND) agglomerates. These freestanding coatings are successfully laser cut into different geometrical shapes. They are found to be optically translucent having high refractive index. Cross-sectional microscopy of the laser cut edge reveals novel melting features of the CVD grown diamond columns.
Indian Journal of Engineering and Materials Sciences 12/2013; 20(6). · 0.41 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related death worldwide, and satisfactory treatment is unavailable. Doxorubicin (DOX) is commonly used for HCC treatment with very limited success and serious side-effects such as cardiotoxicity and non-cancer cell cytotoxicity. Methods: In the present investigation, a new nano-sized hydroxyapatite (HAp)-based drug-delivery system was successfully developed with nano-sized hydroxyapatite (HAp) (sizes 5-30 nm) and synthesised with a Ca/P molar ratio of 1.67. After thorough in vitro characterisation, these nano-HAP particles were loaded/intercalated with DOX (50-60% encapsulation efficiency), and thorough characterisation of the size, shape and morphology of the particles was performed. Results: The average drug-loaded nanoparticles had a spherical morphology with a size range of 40-60 am. The in vitro drug-elution kinetics were examined under different pH conditions to account for the actual pH conditions found in the body environment. The kinetics were observed to be ideal for IV therapy to treat HCC. In vivo experiments using animal models demonstrated very promising results in terms of relative liver weight changes and histopathology Ultimately, 'high-dose' HAp-DOX produced maximum suppression of hyperplastic nodules and a minimum number of preneoplastic lesions. In summary, our results indicate that this new formulation is an efficient, safe and reliable treatment method for HCC. 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Ceramics International 12/2013; 39(8):9557-9566. DOI:10.1016/j.ceramint.2013.05.074 · 2.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Chronic osteomyelitis is a challenging setback to the orthopedic surgeons in deciding an optimal therapeutic strategy. Conversely, patients feel frustrated of the therapeutic outcomes and development of adverse drug effects, if any. Present investigation deals with extensive approach incorporating in vivo animal experimentation and human application to treat chronic osteomyelitis, using antibiotic loaded porous hydroxyapatite scaffolds. Micro- to macro-porous hydroxyapatite scaffolds impregnated with antibiotic ceftriaxone-sulbactam sodium (CFS) were fabricated and subsequently evaluated by in vivo animal model after developing osteomyelitis in rabbit tibia. Finally 10 nos. of human osteomyelitis patients involving long bone and mandible were studied for histopathology, radiology, pus culture, 3D CT etc. up to 8-18months post-operatively. It was established up to animal trial stage that 50N50H samples [with 50-55% porosity, average pore size 110μm, higher interconnectivity (10-100μm), and moderately high drug adsorption efficiency (50%)] showed efficient drug release up to 42days than parenteral group based on infection eradication and new bone formation. In vivo human bone showed gradual evidence of new bone formation and fracture union with organized callus without recurrence of infection even after 8months. This may be a new, alternative, cost effective and ideal therapeutic strategy for chronic osteomyelitis treatment in human patients.
[Show abstract][Hide abstract] ABSTRACT: Hydroxyapatite (HAp)-based highly porous integrated orbital implants with a property of mimicking the movements of fellow eye have been developed recently. Before designing this kind of scaffolds, vascularization and angiogenesis in the constructs need to be considered. Moreover, eye cells expressed with time on these highly porous implants may exert some compressive load whose effect both mechanically and physiologically may indicate its long-term life in vivo. In the present investigation the effect of expression of eye cell lines [rabbit corneal epithelial cell line (SIRC)] on highly porous HAp scaffolds were compared with the normal fibroblastic cells on HAp in general, in terms of in vitro dissolution studies, cell culture cytotoxicity and cell adhesion properties. Elastic properties of macro-porous HAp with a wide range of porosities have also been estimated by ultrasonic non-destructive test methods and the results were compared with its compressive properties for potential application as integrated ocular implants. Cell viability of HAp in contact with SIRC is far better than the L-929 during the initial periods (48 h) but cell adhesion behavior however showed better results in L-929 than the SIRC during the same initial time period. SIRC cells however eventually formed better adhesion properties on the surface of HAp as the days goes by than L-929. High concentration of both Ca and P in culture media might be another factor in cell growth modification. Both the ions had a counter effect on the L-929 and SIRC cells.
Ceramics International 04/2013; 39(3):2651–2664. DOI:10.1016/j.ceramint.2012.09.031 · 2.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Present study aimed to investigate and compare effectiveness of porous chitosan alone and in combination with insulin like growth factor-1 (IGF-1) and bone morphogenetic protein-2 (BMP-2) in bone healing. Highly porous (85±2%) with wide distribution of macroporous (70-900μm) chitosan scaffolds were fabricated as bone substitutes by employing a simple liquid hardening method using 2% (w/v) chitosan suspension. IGF-1 and BMP-2 were infiltrated using vacuum infiltration with freeze drying method. Adsorption efficiency was found to be 87±2 and 90±2% for BMP-2 and IGF-1 respectively. After thorough material characterization (pore details, FTIR and SEM), samples were used for subsequent in vivo animal trial. Eighteen rabbit models were used to evaluate and compare control (chitosan) (group A), chitosan with IGF-1 (group B) and chitosan with BMP-2 (group C) in the repair of critical size bone defect in tibia. Radiologically, there was evidence of radiodensity in defect area from 60th day (initiated on 30th day) in groups B and C as compared to group A and attaining nearly bony density in most of the part at day 90. Histological results depicted well developed osteoblastic proliferation around haversian canal along with proliferating fibroblast, vascularization and reticular network which was more pronounced in group B followed by groups C and A. Fluorochrome labeling and SEM studies in all groups showed similar outcome. Hence, porous chitosan alone and in combination with growth factors (GFs) can be successfully used for bone defect healing with slight advantage of IGF-1 in chitosan samples.
[Show abstract][Hide abstract] ABSTRACT: Microwave heating technique has attracted considerable attention for theprocessing of various materials such as ceramics, glasses, polymers, composites andeven metals. Researchers are trying to apply this technology to new areas. The presentreview presents a short overview of some recent applications of conventional and/ ormicrowave processing for the synthesis of novel ceramics and glass-ceramics.
[Show abstract][Hide abstract] ABSTRACT: The tuning (optimization) of the reactor parameters is very important in order to achieve spatial temperature uniformity across the large area substrate for growing high quality and uniformly thick diamond coatings. It is also important to minimize the thermal stress, arising from temperature non-uniformity, for producing crack free large area diamond coatings. So by varying different process parameters, such as chamber pressure, microwave power, gas flow rate and cavity lengths (by changing the probe, short and stage positions), the resultant variation of substrate surface temperature can be measured. By tuning these parameters the geometry as well as the density of the plasma discharge which directly influences substrate surface temperature may be controlled. It has been shown that by suitable manipulation of the reactor parameters one could achieve at best 80 °C variation in temperature uniformity over 100 mm diameter, which indeed has resulted in a very uniformly thick (± 12.8%) high quality polycrystalline diamond (PCD) coating.
Diamond and Related Materials 11/2012; 30:53–61. DOI:10.1016/j.diamond.2012.10.001 · 1.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The presence of trace level (<1 ppm) carbonate ion in the interlayer space of MgAl-LDH has been
estimated by ion chromatography technique using a novel inverse chemical suppression method using
0.5 mM H2SO4 as mobile phase and 25 mM LiCl as regenerating solution. The presence of carbonate ion in
the LDH structure was found to affect the anion exchange capacity of MgAl-LDH. This has been illustrated
by carrying out anion exchange of nitrate ion in the MgAl-LDH structure with chloride ion. The
importance of this simple but accurate technique for the carbonate ion estimation is demonstrated and
reported in this communication.
[Show abstract][Hide abstract] ABSTRACT: Two different varieties of Si3N4 powders were used to prepare SiAlON ceramics. 100% β-Si3N4 was used from refractory grade powders (B1) and another purer 98% α-Si3N4 (50A) powder was used to prepare the SiAlON samples. Since SiC + SiAlON composites reportedly perform better, batches were prepared with 15% SiC addition to the refractory powders (B1) and 17.5% SiC was added to the other SiAlON composition (50A). The samples were gas pressure sintered at 1840 °C and at 22 bar with 1 h dwelling time. Thereby, we could achieve 97–98% theoretical density. The hardness was recorded 14–17 GPa while fracture toughness varied from 4.3 to 5 MPa m1/2. Fretting experiments showed initial running-in period of 300 cycles for all the tribo-couples. After which, the steady state coefficient of frictions (COF) were achieved. Steel ball of 10 mm diameter, fretting against 50A composition, showed 0.6 average steady state COF while the same composition while fretting against alumina ball of the same diameter, showed 0.57 average steady state COF. Results have been compared with SiAlON composition derived from refractory powder (B1) and found that the 50A composition performs better under identical test conditions. Moreover, cytocompatibility study also suggests that the investigated 50A composition can be used as substrate to support cell adhesion and proliferation of L929 mouse fibroblast cell lines whereas B1 composition derived from refractory powders are toxic in nature.
Ceramics International 09/2012; 38(7):5757–5767. DOI:10.1016/j.ceramint.2012.04.022 · 2.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An alumina ceramic material (purity-96%) was metallized by the conventional molybdenum-manganese (Mo-Mn) process in which an alumina substrate was coated with Mo-Mn paste and subsequently heat treated at 1400 °C for 10 min. During the entire process a moist H2 and N2 gas mixture (dew point-20 °C) with 3:1 ratio was passed continuously through the furnace. X-ray diffraction analysis of the metallized alumina substrate identified only molybdenum phase at the surface of the metallizing layer. The microstructural observations of the metallized alumina substrate were made by scanning electron microscopy. Energy dispersive X-ray analysis showed the elemental compositions along the cross-sectional region of the metallized alumina substrate. The adhesion of the metallic coatings on the alumina substrates was evaluated qualitatively by a scratch testing technique and quantitatively by an adhesion tester. Nanohardness measurements showed gradual change in the nanohardness values across the metallized alumina substrate.
Metals and Materials International 08/2012; 18(4). DOI:10.1007/s12540-012-4010-2 · 1.58 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although the oxide ceramics have widely been investigated for their biocompatibility, non-oxide ceramics, such as SiAlON and SiC are yet to be explored in detail. Lack of understanding of the biocompatibility restricts the use of these ceramics in clinical trials. It is hence, essential to carry out proper and thorough study to assess cell adhesion, cytocompatibility and cell viability on the non-oxide ceramics for the potential applications. In this perspective, the present research work reports the cytocompatibility of gas pressure sintered SiAlON monolith and SiAlON–SiC composites with varying amount of SiC, using connective tissue cells (L929) and bone cells (Saos-2). The quantification of cell viability using MTT assay reveals the non-cytotoxic response. The cell viability has been found to be cell type dependent. An attempt has been made to discuss the cytocompatibility of the developed composites in the light of SiC content and type of sinter additives.
Materials Science and Engineering C 04/2012; 32(3):464-469. DOI:10.1016/j.msec.2011.11.019 · 3.09 Impact Factor