Structures and properties of promising marine anti-cancer, anti-inflammation and anti-infectious (HIV, HSV, malaria, leishmania) compounds reported during 2008–2011 are discussed. Wherever possible, ...attempts have also been made to highlight their possible biogenesis or structure–activity relationships (SAR). Since the stress is on identifying and short-listing potential drug molecules, this review is restricted to only those compounds exhibiting promising in vitro activity, the arbitrary cut off being IC50<15μM, reported during the above period.
•Closed loop analytical modeling of the smart system incorporating the dynamics exhibited by the system and the sensor/actuators is achieved.•Simulations involve testing the effectiveness of the ...designed active controller to real world system inputs at the dominant resonant frequencies.•Multi-mode system excitations are implemented and the effectiveness of the designed state space active controller is proved.•Experimental validation of the developed active controller in controlling the system vibrations at the individual dominant resonant frequencies.
Major physical systems/structures suffer from unwanted vibrations. For efficient working of such systems, these vibrations have to be controlled. In this paper, mathematical modeling of an aluminum cantilever beam with bonded multiple piezoelectric patches which act as the disturbance generator, sensor as well as control actuator has been presented. This piezoelectric laminate cantilever beam is assumed to be vibrating in a single degree of freedom i.e. in the flexural mode only and the corresponding state space models have been derived analytically using the finite element technique. Dominant modes of flexural vibration are identified from the frequency response of the developed model of the system and finally a state feedback controller based on pole placement technique is designed to actively suppress the vibrations. Through numerous simulations as well as experimental validation, the effectiveness of the active controller in damping the vibrations at various excitation frequencies as well as frequency ranges along the flexural mode is established.
► Methane production under the specific conditions in Mexico City was demonstrated. ► Enhanced performance was achieved with pH control and nitrogen addition. ► Co-digestion of FVW with meat residues ...allows high and stable performance (30L). ► The microbial population in the AD system during optimal performance was determined. ► Bacterial and Archaea populations were correlated with its function in the AD system.
This study evaluated the feasibility of methane production from fruit and vegetable waste (FVW) obtained from the central food distribution market in Mexico City using an anaerobic digestion (AD) process. Batch systems showed that pH control and nitrogen addition had significant effects on biogas production, methane yield, and volatile solids (VS) removal from the FVW (0.42mbiogas3/kgVS, 50%, and 80%, respectively). Co-digestion of the FVW with meat residues (MR) enhanced the process performance and was also evaluated in a 30L AD system. When the system reached stable operation, its methane yield was 0.25 (m3/kgTS), and the removal of the organic matter measured as the total chemical demand (tCOD) was 65%. The microbial population (general Bacteria and Archaea) in the 30L system was also determined and characterized and was closely correlated with its potential function in the AD system.
Creep rupture behavior of 9Cr–1.8W–0.5Mo–VNb (ASME grade 92) ferritic steel weld joint fabricated by activated TIG (A-TIG) welding process have been investigated at 923K over a stress range of ...80–150MPa. The weld joint was comprise of fusion zone, heat affected zone (HAZ) and base metal. The HAZ consisted of coarse prior-austenite grain (CGHAZ), fine prior-austenite grain (FGHAZ) and intercritical (ICHAZ) regions in an order away from the fusion zone to base metal. A hardness trough was observed at the outer edge of HAZ of the weld joint. TEM investigation revealed the presence of coarse M23C6 precipitates and recovery of martensite lath structure into subgrain in the ICHAZ of the weld joint, leading to the hardness trough. The weld joint exhibited lower creep rupture lives than the base metal at relatively lower stresses. Creep rupture failure location of the weld joint was found to shift with applied stress. At high stresses fracture occurred in the base metal, whereas failure location shifted to FGHAZ at lower stresses with significant decrease in rupture ductility. SEM investigation of the creep ruptured specimens revealed precipitation of Laves phase across the joint, more extensively in the FGHAZ. On creep exposure, the hardness trough was found to shift from the ICHAZ to FGHAZ. Extensive creep cavitation was observed in the FGHAZ and was accompanied with the Laves phase, leading to the premature type IV failure of the steel weld joint at the FGHAZ.
Effect of thermo-mechanical processing on tensile behaviour of reduced activation ferritic martensitic (RAFM) steel has been assessed and compared with those of the normalized and tempered steel. The ...thermo-mechanical treatment (TMT) was carried out by performing hot rolling and ageing in the austenite phase field, air cooled followed by tempering. TMT of the steel increased its hardness compared to the normalized and tempered condition. Tensile strength of the steel increased on TMT over the investigated temperature range of 300–923 K and more importantly was accompanied with increase in ductility. The strength increase on TMT was accomplished with the refinement of microstructure of the steel having finer martensite lath size and intra-granular precipitates. The tensile flow behaviour of steel has been assessed in the frame work of Voce's constitutive equation. The strength related parameters of the constitutive equation i.e. initial stress and saturation stress increased on TMT, while the recovery related parameter (nv) decreased marginally. The enhancement of tensile strength and ductility of the steel on TMT is considered due to microstructural refinement and its enhanced stability as reflected in appreciable lower relaxation and creep rates and the delayed in onset of tertiary stage of creep deformation.
•Cyclic life (Nb) decrease with increase in the temperature and block size (Bs).•Dynamic strain aging (DSA) supressed ratcheting strain accumulation.•Significant strain accumulation took place at ...923K through ratcheting and creep.•Fracture mode in CCF is through LCF (striations), creep (intergranular facets) or ratcheting (dimples).•HCF damage acts as an catalyst by linking up intergranular creep cracks and transgranular LCF cracks.
The present study investigates the effect of different damage modes like low cycle fatigue (LCF), high cycle fatigue (HCF), creep and ratcheting during combined cycling at various temperatures ranging from ambient to 923K, in a type 316LN austenitic stainless steel. The experiments were designed with multi-step load sequences where specific number of small amplitude HCF cycles (referred to as blocks) were introduced at the stabilized cyclic load under LCF for a given strain amplitude and repeated until failure. Cyclic life was found to decrease with increase in temperature as well as block-size. The decrease in cyclic life with block-size is more significant at 923K where multiple damage modes like creep and ratcheting are activated. Dynamic strain aging (DSA) was found to operate in the temperature range, 823–873K where the decrease in cyclic life with block-size gets saturated. Typically, transgranular fatigue fracture, intergranular creep fracture or dimpled rupture was identified when failure was dictated by LCF, creep and ratcheting respectively. However, synergistic interaction between the above damage modes leading to a mixed mode fracture carrying signatures of fatigue striations, intergranular facets and dimples occurred at specific combinations of block size and temperature. HCF damage played an important role for some specific loading conditions by acting as a link between intergranular (creep) cracks, thus facilitating the crack propagation and final failure. The regimes of dominant failure modes and interactions among them were suitably mapped as a function of temperature and block size.
Nano titanium dioxide (TiO2) synthesized by sol-gel route was calcined at different temperatures, the powder calcined at 673 K indicates biphasic mixture of brookite and anatase. On the other hand ...the powder calcined at 773 K exhibited three phase mixture of anatase, brookite and rutile phases. The microstrain present in the multiphasic powder was studied by the X-ray diffraction Williamson - Hall method. Detailed Rietveld analysis with line profile analysis combined with spherical harmonics indicated the anisotropic microstrain in the calcined powders. The strain was found to reduce with calcination temperature. The anisotropic microstrain is correlated to oxygen vacancies, which influence the crystal structure parameters of the phases in terms of their TiO6 octahederal bond length/bond angle values. The bond valence sum analysis of the powders confirms for the oxygen vacancy in the titania powders.
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•Nano-titania powders were synthesized via Sol-gel route.•The calcined powders have anisotropic crystallite size and anisotropic microstrain.•Structural analysis of nano-titania through Rietveld analysis, Bond Valence Sum.•The Bond Valence studies suggest the presence of oxygen vacancy in the lattice.•Oxygen vacancy, microstrain may be the driving force of phase transformation.
The present study investigates the effect of different damage modes like low cycle fatigue (LCF), high cycle fatigue (HCF), creep and their interactions during combined cycling at high temperature ...(923K) in a 316LN stainless steel. The experiments were designed with multi-step load sequences where specific number of small amplitude HCF cycles (block) were introduced at the stabilized cyclic load under LCF for a given strain amplitude and repeated until failure. Cyclic life was found to decrease with the increase in HCF block size. However, the extent of decrease in cyclic life also depends on the LCF strain amplitude, which is attributed to the additional damage incurred by creep and ratcheting. Creep damage was found to be opposed by a strong compressive ratcheting originating from Bauschinger effect, resulting in net strain accumulation in tensile or compressive direction depending on whichever damage process of the two is dominant. Typically, fatigue fracture, intergranular creep fracture or creep rupture can be identified when failure was dictated by LCF or creep. However, failure life was actually found to be governed by multiple damage interactions between LCF, HCF and creep for specific loading conditions, as emphasized through detailed fracture surface investigations. HCF damage was found to act as a catalyst by joining small transgranular (LCF) or intergranular (creep) cracks, thus facilitating the crack propagation and final failure by the respective modes. This leads to strong synergistic LCF-HCF-creep or HCF-creep interaction, the regimes of which were suitably mapped as a function of LCF strain amplitude and block size.
•10 mm thick RAFM steel is welded by A-TIG welding process with two passes.•Post Weld Heat Treatment (PWHT) conditions are optimized for A-TIG weld joint.•Harder martensite forms in the A-TIG weld ...metal.•Strength properties are better for A-TIG weld joint.
Reduced Activation Ferritic-Martensitic steels (RAFM) are chosen as the candidate material for structural components in fusion reactors. Gas Tungsten Arc (GTA) welding is one of the candidate process for fabricating the structural components made of RAFM steel. A variant of GTA welding process called as Activated Tungsten Inert Gas (A-TIG) welding has been reported to overcome the limitations of GTA welding and enhance creep rupture life in F–M steels. In the present work, 10 mm thick RAFM steel is welded by conventional TIG and A-TIG welding processes and the effect of welding techniques on the microstructure and mechanical properties are compared. Post Weld Heat Treatment (PWHT) conditions are optimized in A-TIG weld joint to get improvement in impact toughness values. TEM investigation on weld metals revealed that the martensite lath and prior austenitic grain boundaries are decorated with M23C6 precipitates and the lath size was in the range of 0.3 -0.4 μm. Very fine MX precipitates are seen in intra martensite laths and very fine sub grain formation was observed after tempering treatment. Hardness and strength properties are higher for A-TIG weld joint while ductility is similar for both the weld joints. An impact toughness of 155 J was obtained in the A-TIG weld joint on full size sample.
The electrooxidation of high strength leachate from an industrial solid waste landfill site was carried out in a three-dimensional carbon bed electrode reactor (TDR). This paper discusses the ...kinetics and mechanism of electrooxidation on the basis of time course variation of COD, TOC and TKN (total Kjeldahl nitrogen) from the raw leachate. The batch experiments were run at different applied currents (1–3 A) for a period of 6
h. A two-stage pseudo-first order reaction kinetics model was developed based on the initial rapid removal of pollutants (Phase I) followed by slow oxidation kinetics (Phase II). About 60–64% COD was removed within 1
h with a rate constant 5.83
×
10
−3 min
−1 in Phase I, which was near 5–7 times greater than that of Phase II (0.81–1.03
×
10
−3
min
−1). The mineralization efficiency was found to be significant in the range 0.83–0.84. The apparent faradic efficiency and specific energy consumption for COD removal were also estimated. The mechanism of electrooxidation was discussed with the help of adsorption, kinetic and SEM results.
