Studies on the antibacterial potentiality of isoflavones Dastidar, Sujata G; Manna, A; Kumar, K.Asok ...
International journal of antimicrobial agents,
2004, 2004-Jan, 2004-01-00, 20040101, Volume:
23, Issue:
1
Journal Article
Peer reviewed
The isoflavonoid compounds ‘YS11–YS21’ were screened for possible antimicrobial property against 12 known Gram-positive and Gram-negative sensitive bacteria. YS11 and YS16 failed to show ...antimicrobial activity and YS12, 13, 14, 15, 17, 18 and 20 had moderate antimicrobial action. Compounds YS19 and YS21 showed pronounced antimicrobial property. YS19 and YS21 were then tested in vitro against 214 strains of bacteria from one Gram-positive and six Gram-negative genera. The minimum inhibitory concentration (MIC) of YS19 and YS21 was determined by agar dilution method and ranged from 25 to 200
mg/l in most strains. At concentrations of 30 and 60
μg/mouse these compounds offered significant protection to mice challenged with 50 median lethal dose (MLD) of a virulent strain of
Salmonella Typhimurium.
Purpose - This paper aims to perform numerical simulations through different shaped double stenoses in a vascular tube for a better understanding of arterial blood flow patterns, and their possible ...role during the progression of atherosclerosis. The dynamics of flow features have been studied by wall pressure, streamline contour and wall shear stress distributions for all models.Design methodology approach - A finite volume method has been employed to solve the governing equations for the two-dimensional, steady, laminar flow of an incompressible and Newtonian fluid.Findings - The paper finds that impact of pressure drop, reattachment length and peak wall shear stress at each restriction primarily depends upon percentage of restriction, if restriction spacing is sufficient. The quantum of impact of pressure drop, reattachment length and peak wall shear stress is much effected for smaller restriction spacing. If recirculating bubble of first restriction merges with the recirculating bubble formed behind the second restriction in this smaller restriction spacing. The similar effect of smaller restriction spacing is observed, if Reynolds number increases also.Originality value - The effect of different shaped stenoses, restriction spacing and Reynolds number on the flow characteristics has been investigated and the role of all the flow characteristics on the progression of the disease, atherosclerosis, is discussed.
► We examined long-term effect of manure and fertilizers application on soil organic carbon pools ► We studied temperature sensitivity of C pools and alterations in microbial composition ► ...Established the relationship between productivity and climatic parameters ► Physico-chemical degradation and changes in microbial composition may decline in crop yields.
Global climate change is anticipated to have a tremendous influence on crop productivity and nutrient cycling in legume-based cropping systems. The effect of long-term application of manure and fertilizers on the dynamics of soil organic carbon (SOC) pools and soil physical properties was studied in a soybean (Glycine max Merr. L)–wheat (Triticum aestivum L.) system. The temperature sensitivity of C pools and the alterations in microbial composition were determined at 25, 35, and 45°C. Higher levels of microbial biomass C (MBC) and nitrogen (MBN), water soluble carbon (WSC), acid hydrolysable carbohydrates (AHC), particulate organic matter carbon (POMC) and nitrogen (POMN) were observed in the NPK+FYM at a depth of 0–15cm. Irrespective of the treatment, micro aggregates (53–250μm) were a major aggregate size class, comprising 45–57% of the total soil aggregates, followed by macro aggregates (250–2000μm at 37.8–45%). Microbial respiration rate increased by 13.9% in most recalcitrant pools (<53μm) at 45°C than at 25°C. Furthermore, data on labile C (A0) revealed a 4.9–55.4% increase in the substrate pools and a 10.5–32.5% increase in mineralization rate (k) with these treatments at 25–45°C in 250–2000μm aggregates. AHC and POMC content decreased by 23–37% and 12–23% of SOC, respectively, when the temperature was raised from 25 to 45°C. It is concluded the gradual depletion of nutrients, structural degradation and changes in microbial composition might have collectively contributed to the decline in crop yields. It was suggested that temperature has a strong effect on C mineralization, depending on the types and extents of substrate utilization. Seasonal rainfall, maximum and minimum temperature and SOC had jointly explained 12–41% of variation in soybean production in NP, NPK and NPK+FYM treatments. However, balanced use of NPK plus FYM is an important management option to arrest the decline of crop yield.
Commercial purity aluminum was deformed by equal channel angular pressing (ECAP) using steel dies producing two different shear strains of either 1.15 or 0.60 in each pass. Two sets of samples were ...selected for study, of which the first set consists of aluminum billets repeatedly deformed without changing orientation (process A) up to three passes using first die. The second set of samples was equal channel angular pressed (ECAPed) using the second die up to 10 passes adopting process B
c
, where samples were rotated by 90 deg between successive passes. The flow patterns were revealed by optical metallography. Tensile strength and hardness were measured. The ECAPed samples were isochronally-annealed and recrystallization behavior was studied by microscopy and Vickers hardness measurements. Refinement of grain size, substructure, and texture was studied by transmission electron microscopy (TEM) and orientation imaging microscopy (OIM). The results show that flow patterns are complex and distinct from simple shear. Strain is higher at the outer surfaces, highest at the bottom surface, and intermediate in the middle of the billet. The work piece strain hardens significantly in first pass with an attendant drop in ductility. The degree of strengthening reduces in subsequent passes. The high defect density introduced during the initial passes leads to grain refinement to an ultrafine level and advantageously the material regains ductility. The refinement in microstructure obtained after two to three passes is stable up to 250 °C. The flow patterns are very similar to those obtained by physical modeling in our earlier studies using plasticine. Equiaxed ultrafine-grained structure (average grain size = 0.53
μ
m) was obtained after ECAP at an equivalent shear strain of 6.0.
We report here the results of our physical modeling study of the equal channel angular pressing process using two-colour constituent plasticine workpieces in a metallic die. The workpieces, usually ...called billets, are made up of discs as well as spherical balls. They are deformed repeatedly with and without changing the orientation between successive passes. Both square and round dies with inner channel intersection angle of 90° are used. The flow patterns are revealed by sectioning the billet after a requisite number of passes. Thorough mixing of the two constituents with a drastic reduction in the section size of each constituent of the plasticine workpiece was observed after 15 passes. The initial shape of the constituents of the billet does not affect the final flow pattern of the microstructure. Material accumulation of the two colour constituents of plasticine was observed in some regions of the billet along the central region at a low and intermediate number of passes.
Developments of microstructures and texture are investigated for a low-carbon steel deformed by equal-channel angular pressing (ECAP) at room temperature for equivalent strain (
ε
vm
) of 16.8. ECAP ...at
ε
vm
= 0.6 reduces grain size by two orders of magnitude. With increasing strain, grain size reduces further and high-angle grain boundary (HAGB) fraction improves by grain subdivision and its change in orientation. ECAP of low-carbon steel up to
ε
vm
= 16.8 can produce ultrafine grains of 0.2 µm size with HAGB fraction of 82%. The as-received steel has low texture index. Microstructural changes strongly influence texture development. It increases with equivalent strain as grain subdivision continues. Texture index fluctuates at intermediate strain range due to randomization of initial texture. Texture index reaches saturation at the high equivalent strain. On ECAP at low to intermediate strain
ε
vm
= 0.6-6, components of both
α
(
F
θ
,
J
θ
, and
J
¯
θ
) and
γ
(
D
1
θ
,
D
2
θ
, and
E
θ
) fibers are developed though all of them deviate from their ideal positions. At higher strain (
ε
vm
= 9-16.8), the
γ
fiber components (
D
1
θ
,
D
2
θ
,
E
θ
) are strengthened, and the
E
θ
component reaches the highest intensity of ≈ 17 at
ε
vm
= 12. There is no texture symmetry at low to high strain level. The presence of pearlite in low-carbon steel enhances strongly the deviation of texture components from their ideal positions in Euler’s space as well as it increases the intensities of the components more than that of IF steel for a similar equivalent strain.
In the present paper, the comparison of steady, simple pulsatile flow and physiological pulsatile flow on flow reversal zone and hemodynamic wall parameters wall shear stress (WSS) and oscillatory ...shear index (OSI) for the progression of the disease, atherosclerosis has been investigated numerically. The governing equations have been solved by finite volume method. For the numerical analysis, Womersley number, Reynolds number and percentage of restriction are taken as 10, 100 and 50 % respectively. From this study it is revealed that the separated flow from the stenosis strongly depends on inlet flow situations, the maximum chance of deposition of plaque material due to streamline contour is higher at time step t* = 0.75 for simple pulsatile flow and at time step t* = 0 for physiological pulsatile flow and this chance is lower in case of steady flow. The effect of WSS on the disease is higher in physiological pulsatile flow compared to steady as well as simple pulsatile flow. The maximum possibility of initiation as well as progression for atherosclerosis in arterial wall due to high WSS takes place at t* = 0.25 for physiological pulsatile flow. OSI indicates same length of separation for two cases of transient flow, but the rate of cyclic departure of WSS is higher in case of physiological pulsatile flow.
Numerical solutions of the steady viscous flow in the neighborhood of different double stenoses are obtained under laminar flow conditions with the motivation for modeling blood flow through stenosed ...artery formed due to arterial disease. The flowing blood is considered to be incompressible and Newtonian. A finite volume method has been employed to solve the governing equations. The dynamics of flow features have been studied by wall pressure, streamline contour, and wall shear stress distributions for all models. The results have demonstrated that when the shapes of stenosis change at primary stenosis keeping no change in the shape of secondary stenosis, the impact of changes in primary stenosis on secondary one is noted to be more, whereas, no impact of primary stenosis on secondary stenosis and vice versa is observed in case of changes in the shapes of secondary stenosis keeping no change in the shape of primary stenosis. When Reynolds number changes, the impact of changes in primary stenosis on secondary one is also noted to be higher.
•Ultra high strength bulk nanostructured LCS is produced by ECAP followed by cryorolling.•Flash annealing can produce bimodal microstructures in single phase LCS.•600 °C is found to be optimum ...temperature for flash annealing.•Novel microstructure of single phase bimodal grains distribution.•Recovery, recrystallization and secondary recrystallization.
The low carbon steel (LCS) rods were plastically deformed at room temperature up to a very high strain level by equal channel angular pressing (ECAP). ECAPed samples were further cryo-rolled at subzero temperature up to 94% area reduction. After plastic deformation, samples were annealed for short period at 475–675 °C temperature range. Optical microscopy and transmission electron microscopy are used to characterize primary microstructure and fine microstructural details respectively. Hardness of the deformed and annealed samples is measured by Vickers hardness testing. Results show that the grains are refined from 65 µm to 200 nm by ECAP at equivalent strain of 16.8, further grains are refined to <78 nm by cryo-rolling at −50 °C with increase in dislocation density. The cryo-rolling of ultrafine grained (UFG) LCS increases the hardness due to further grain refinement and the increased dislocation density. Hardness of the UFG LCS produced by ECAP is more than three times of coarse grained LCS. Flash annealing (at a range of temperature) of cryo-rolled UFG LCS is produced the single phase bimodal microstructure. Bimodal microstructure is the consequence of secondary recrystallization during flash annealing. Even after flash annealing of ECAP-16.8-CRR-94 deformed sample, hardness is more than 200% of as-received LCS and it decreases with increase in flash annealing temperature.In this study recrystallization, secondary recrystallization and hierarchy in grain growth with increasing annealing temperature is presented. Microstructure and mechanical properties correlation is demonstrated.
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