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Development of continuously cooled low-carbon, low-alloy, high strength carbide-free bainitic rail steels
No full textIn the present work, attempts have been made to design and develop low-carbon, low-alloy, high strength
carbide-free bainitic steels for application in heavy-haul rail tracks. The study starts with an analytical approach for understanding the effects of different alloying elements on the thermodynamic and kinetic aspects of bainite transformation and the resultant microstructure and mechanical properties. Based on the analysis, two steel compositions were designed for further investigation. The alloys were prepared by melting and casting and processed by hot-rolling and air cooling, which is the usual route for the industrial production of rail sections. Microstructures of the developed steels primarily consisted of plates of carbide-free bainitic ferrite, interspersed with fine films of retained austenite. These continuously cooled steels offer ultra-high strength levels with very good ductility which are far superior to existing pearlitic grade rail steels. Detailed characterization and quantification of microstructural constituents have been carried out and they are correlated with the tensile proprieties using semi-empirical formulations available in literature
Mechanical properties and age hardening response of Al6061 alloy based composites reinforced with fly ash
No full textStir casting method was adapted to develop Al6061 alloy composite using plasma treated fly ash. Properties of this material were compared with the virgin Al6061 alloy and A16061 alloy-fly ash composite. Differential scanning calorimetric study revealed precipitation of GP zone, beta '' and beta' phases for all systems. Characterization of different phases in the system was carried out using transmission electron microscopy. It has been revealed that plasma treated fly ash-Al6061 alloy composite exhibited maximum matrix strain and defect density and thus, yields faster response to age hardening when compared with parent Al alloy and Al alloy-fly ash composites. Mechanical properties of in-situ synthesized fly ash-Al alloy composite unveiled superiority in comparison to other two systems in cast condition
Structural and Mechanical Behavior of Mechanochemically Synthesized Nanocrystalline Hydroxyapatite from Mercenaria Clam Shells
No full textThe aim of the present investigation is to develop mechanochemically synthesized nano-crystalline hydroxyapatite (nHAp) bioceramics using clam seashells and phosphoric acid by varying the CaO:H3PO4 acid at different wt% ratios, i.e. 1:0.75, 1:1.0, 1:1.25, 1:1.5 and 1:1.75. The synthesized powders were characterized using X- ray diffraction ( XRD), scanning electron microscope and high resolution transmission electron microscopy. XRD results showed that the average crystallite size of the powder varies from 54 to 69 nm with enhancement in its crystallinity from 85 to 96%. An attempt was laid to access the mechanical behavior of nHAp through indentation at the micron scale. Microindentation derived properties, viz. microhardness, fracture toughness, brittleness index and fracture energy showed significant variation with CaO:H3PO4 mixing ratio due to the evolution of HAp and other calcium phosphate based phase(s). The fracture behavior illustrated a considerable improvement with the variation in CaO:H3PO4 mixing ratio
Techniques for investigation: Semiconductor/electrolyte interface processes in photo electrochemical cell for solar water splitting
No full textPhoto-electrochemical water splitting process for solar hydrogen production has attained great consideration due to acceptance of hydrogen as a sustainable and environmentally friendly energy carrier. The key functional components of a PEC cell are the semiconductor electrode and semiconductor-electrolyte interfacial junction. The semiconductor-electrolyte interface, the other crucial functional unit of PEC cell is rarely investigated. The nature of the charge carrier’s movement at the semiconductor/electrolyte interface is fundamental for the optimization of semiconductor electrode performance for efficient hydrogen generation. To understand the above processes at the interface, various techniques are being used to investigate the electrochemical reactions and photocatalytic response of a stable photoelectrode. In this review, the charge transfer kinetics and various methods used to investigate the e-
/h+ transfer processes at the semiconductor/electrolyte interface are reviewed and discussed
The role of nanomedicine in the treatment of osteosarcoma and in the prevention of infections
No full textOsteosarcoma is the most common bone cancer in children and the third most common cancer in adolescence. The current survival rate for osteosarcoma is 60-70% which has not improved over the past two decades. The treatment of osteosarcoma is complicated by cytotoxicity and side effects of various therapeutic drugs and osteosarcoma can also be accompanied with infection which can happen post-surgical resection or can be associated with implants causing graft rejection. The goal of utilizing nano-medicine in the treatment of osteosarcoma is to take advantage of nanocarriers for specific targeted drug delivery to cancer cells and to lower the negative impact of drugs on normal cells. Further, nanoparticles can prevent infections in patients. In this paper, we review specific nanomaterials, various micelleplexes, and their role in targeted drug delivery to osteosarcoma cells. We will also review the anti-cancer effect of nanoparticles that should replace chemotherapy in the future. This paper also reviews the role of nanoparticles in passive and active targeting of osteosarcoma cells and the role of nanocomposites in cancer treatment and infection prevention in the osteosarcoma
Limiting platelet adhesion in stainless steel bio-implants through microstructural modification
No full textThrombosis, resulting from platelet adhesion and attachment is one of the major issues with blood contacting implants. Limiting platelet adhesion is highly desirable to ensure the usefulness of implants in blood
contacting applications. In this work, we report on simplistic low-temperature high strain-rate processing to
minimize the platelet adhesion on biomedical grade stainless steel. In addition, processing was also done at low rotational speed to study the effect of strain rate during processing. At high rotational speed, the processed steel resulted in single-phase ultra-fine grain structure along with significantly lower metal ion-release and better hemocompatibility. In addition, increased cellular viability with no significant morphological aberrations were observed in processed specimen in Human Wharton's jelly derived mesenchymal stem cells (HW-MSCs). Higher
resistance for platelet adhesion for the processed steel is explained by favorable electronic characteristics of the metal-oxide and short-range polar interactions at the cell-substrate interface. Higher stability of the metal-oxide on processed steel contributed towards reducing the metal-ion release and ensure better hemocompatibility
Some notable experiments of graphene
No full textGraphene is an allotrope of carbon where carbon atoms are attached through sp2 hybridization in a two-dimensional (2D) plane. Based on the structure, graphene can be visualized as a single sheet of graphite. A. Geim and K. Novoselov successfully isolated free standing monolayer graphene from graphite by scotch tape method for the first time in 2004. This discovery won them the Nobel Prize in physics 2010. However, several inception experiments had been carried out much before its birth by other eminent scientists. In fact, several extended experiments have been performed to understand the properties of graphene after its discovery. This article is a collection of some of the notable pre and post-discovery experiments. In addition, it includes some of the experiments those have been carried out at CSIR-NML
Improved Reactivity of Volcanic Ash using Municipal Solid Incinerator Fly Ash for Alkali-Activated Cement Synthesis
No full textIn this work, municipal solid waste incinerator fly ash (MSWI-FA) was used as precursor to alter the reactivity of low reactive volcanic ash (VA) for alkali-activated cement synthesised. The effects of various proportions of MSWI-FA (0, 5, 10, 15 and 20%) on the final properties of the inorganic polymer are reported. The increase in MSWI-FA content increases the heat of reaction in MSWI-FA as the result of the reaction between the amorphous alumina-silica and the Ca-rich precursor. Isothermal conduction calorimetry, FTIR, XRD SEM/EDS, and physico-mechanical analyses were used to follow up the different formulations. New crystalline phases, namely Margarite (CaAl2 (Al2Si2)O10(OH)2, PDF#04-013-3004), Mordernite-(Ca) ((Ca, Na2, K2)(Al2 Si10 O24)·7H2O, PDF#00-011-0155) and Thernadite (Na2SO4, PDF#01-074-2036) confirm the good reactivity. The SEM/EDS exhibited the coexistence of C–S(-N-A)–H and N-A-S-H gels in binary system alkali-activated. The compressive strength and bulk density ranged from 9.38 to 21.07 MPa and from 1.56 to 1.77 g/cm3, respectively. These results indicated the possibility to use VA and MSWI-FA to synthesize room temperature alkali-activated matrices applicable in the manufacture of structural and functional materials. MSWI-FA appears energy-efficient and sustainable solution for the improvement of the volcanic ash based alkaline activated materials
Ratcheting Fatigue Behavior of Modified 9Cr-1Mo Steel at Room Temperature
No full textFusion reactor components undergo asymmetric cyclic loading,that leads to a progressive increase in plastic strain and causes deterioration in life of engineering components. This investigation deals with fatigue behavior of modified 9Cr-1Mo steel at room temperature and presents the effect of mean stress (sigma(m)), stress amplitude (sigma(a)) and stress rate ((sigma) over dot) on fatigue life, deformation and fracture behavior under asymmetric cyclic loading. A series of fatigue tests were conducted under asymmetric stress-controlled loading with different combinations of sigma(m) (190-210 MPa), sigma(a) (400-420 MPa) and (sigma) over dot (50-450 MPa/s). The plastic strain increased with increase in sigma(m) and sigma(a) and the fatigue life was reduced, whereas increase in (sigma) over dot reduced the accumulated plastic strain and the cyclic life was increased. The deformation behavior and microstructural changes under the influence of the three parameters (sigma(m), sigma(a) and (sigma) over dot) were examined by tranmission electron microscope (TEM). With increase in the three parameters (sigma(m), sigma(a), (sigma) over dot), the lath martensitic structure changed to subgrain structure along with dislocation cells and forest dislocations. Scanning electron microscopy revealed unique features of fractured specimens, with progressive reduction in diameter towards the fracture-end, fatigue striations on the tapered circumferential surface and dimples on the fracture surface
Study on interaction of p-sulfonato calix[6]arene with arsanilic acid
No full textThe interaction of p-sulfonatocalix[6]arene (PSC6) with o-arsanilic acid (OASA) and p-arsanilic acid (PASA) was studied by UV-Visible spectroscopy, high-performance liquid chromatography (HPLC) analysis, photoluminescence (PL) spectra, and nuclear magnetic resonance (NMR) studies. The studies confirm the inclusion of PASA in PSC6 cavity