Association of Small Dense LDL with Coronary Artery Disease and Diabetes in Urban Asian Indians - The Chennai Urban Rural Epidemiology Study (CURES-8)

Objective: Earlier studies in Europeans have identified small dense LDL to be associated with coronary artery disease and diabetes. In this study we assessed the association of small dense LDL with diabetes and CAD in Asian Indians. Methods: Study subjects were selected from the Chennai Urban Rural Epidemiology Study (CURES), a population based study on representative sample of Chennai city in southern India. Group 1:non-diabetic subjects (n=30); Group 2: diabetic subjects without CAD (n=30); Group 3:diabetic subjects with CAD (n=30). LDL subfractions were estimated using LipoPrint LDL system. LDL subfractions 3 and above, defined as small dense LDL was summed up to determine the overall small LDL. 75th percentile of the overall small dense LDL in non-diabetic subjects was used as a cut-off for defining elevated levels of small dense LDL. Results: The mean age of the study subjects was not significantly different among groups. Overall small dense LDL was significantly higher in diabetic subjects with CAD (16.7 ± 11.1 mg/dl, p<0.05) and without CAD (11.1 ± 8.0 mg/dl, p<0.05) compared to non-diabetic subjects without CAD (7.2 ± 6.8 mg/dl). Small dense LDL showed a positive correlation with fasting plasma glucose (r=0.252, p=0.023), HbA1c (r=0.281, p=0.012), total cholesterol (r=0.443, p<0.001), triglycerides(r=0.685, p<0.001), LDL(r=0.342, p=0.002), total cholesterol/HDL ratio (r=0.660, p=<0.001) and triglycerides/HDL ratio(r=0.728, p<0.001) and a negative correlation with HDL cholesterol (r= -0.341, p=0.002) and QUICKI values (r= -0.260, p=0.019). ROC curves constructed to predict elevated small dense LDL ((9.0 mg/dl) revealed that triglycerides/HDL ratio and total cholesterol/HDL ratio had higher AUC values compared to other parameters. A triglycerides/HDL ratio of 3.0 had the optimum sensitivity (80.0%) and specificity (78.0%) for detecting elevated small dense LDL. Conclusion: This data suggests that in Asian Indians, small dense LDL is associated with both diabetes and CAD and that a triglycerides/HDL ratio (3.0 could serve a surrogate marker of small dense LDL

Strain Rate Dependent Behavior of Glass/Nano Clay Filled Epoxy Resin Composite

It is believed that addition of small amount of nanoclays in the neat epoxy and fiber reinforced epoxy composite system can improve the mechanical properties. The mechanical properties of most of polymer matrix composites are sensitive to testing rate. However, most of the researches were concentrated on the behavior of the polymermatrix composites at high strain rates. The present research work is to investigate the role of clay on neat epoxy and glass–fiber reinforced epoxy composites, at low strain rates. The clay in terms of 1.5 wt%, 3 wt%, and 5 wt% are dispersed in the epoxy resin using mechanical stirring followed by sonication process. The corresponding glass/epoxy nanocomposites are prepared by impregnating the clay epoxy mixture by hand lay-up process. Characterization of the nanoclay is done by X-ray diffraction and Scanning Electron Microscopy. Tensile stress-strain curves are obtained at strain rates of 10-4 s-1, 10-3 s-1, 10-2 s-1, and 10-1 s-1 by a hydraulic  machine reporting that, even at low strain rates, the longitudinal strength and stiffness increase as strain rate increases for all clay loadings. It is observed that the tensile modulus increases as the clay loading increases for both epoxy and glass/epoxy nanocomposites. It is also noticed that the longitudinal tensile strength decreases as the clay loading increases. The failed specimens show marked changes in the fracture surface with increased strain rate. Scanning electron microscopy is used to study the fiber/matrix/clay adhesion in fracture surfaces.Defence Science Journal, Vol. 64, No. 3, May 2014, pp. 295-302, DOI:http://dx.doi.org/10.14429/dsj.64.733

Optimal Design of Filament Wound Grid-stiffened Composite Cylindrical Structures

An integral account of design and analysis of grid-stiffened cylindrical structures is presented. For convenience, a two-phase approach is adopted. In the initial phase, with a view to arriving at a few initial possible optimal configurations, parametric analysis through smeared stiffeners approach is utilised. The ribs, in a filament wound grid-stiffened structure, introduce several additional design elements that result in many possible design configurations; in the initial phase, these design options are efficiently reduced to a few numbers. Finite element modelling is used in the final design and analysis. Rib material is distinct from normal unidirectional composites and this aspect is inherently accounted for in the modelling approaches considered here.Defence Science Journal, 2011, 61(1), pp.88-94, DOI:http://dx.doi.org/10.14429/dsj.61.48

Buckling Analysis of Composite Hexagonal Lattice Cylindrical Shell using Smeared Stiffener Model

Hexagonal lattice pattern formed by helical and circumferential ribs is the most common among different possible lattice patterns. An energy-based smeared stiffener model (SSM) is developed to obtain equivalent stiffness coefficients of a composite lattice cylindrical shell with such hexagonal lattice patterns. Using the equivalent stiffness coefficients, Ritz buckling analysis was carried out. Extensive finite element modelling covering different representative sizes have been carried out. SSM is validated by comparing the estimated buckling loads. Variation of material properties of rib unidirectional composites from those of normal unidirectional composites is accounted for in the energy  formulations.Defence Science Journal, 2009, 59(3), pp.230-238, DOI:http://dx.doi.org/10.14429/dsj.59.151

Perforation of Layered Composite Plates byImpactors of Different Nose Shapes

Conical and hemispherical nose-shaped cylindrical impactors have been used in drop weightimpact experiments on 3.1 mm CSM-polyester laminated plates. Based on experimental results,various failure mechanisms and energy absorbed in different failure modes are identified and calculated.It is found that the damage area beyond a certain value of impact energy does not increase. Theperforation geometry is the same as that of the impactor irrespective of increased crack length, andcomplete rotation of petals takes place at impactors radius. It is also observed that the crack lengthincreases with decrease in contact area. But, when the nose is sharp (5 mm hemispherical nose), thereis no extended crack beyond perforated region. Blunt nosed (truncated conical impactor with 10 mmnose dia) impactors cause more number of petals/cracks than 10 mm hemispherical nosed impactorand less than 5 mm hemispherical nosed impactor. The petals formed by a cylindrical impactor with40 mm hemispherical nose are unequal in size, whereas in the case of conical impactors, these areequal. At lower energies, blunt nosed impactors cause more delamination than the hemisphericalones, and at higher energy, it is the reverse. It is found that there exist many visible concentriccircular ring hinge mechanisms at the top surface of plates

Energy Absorption Characteristics of Metallic and Composite Shells

Metallic and composite shells of different sizes and tubes were subjected to axial compression in an Instron Machine. Their progressive failure modes and energy absorption capacities have been studied. In the case of metallic shells, analytical expressions are derived to find the mean collapse load and the fold length based on the formation of plastic hinges. Theoretical results have been compared with experimental results wherever possible. The effect of internal folding on the post-collapse behaviour of round tubes has been discussed and expressions for fold length and post-collapse load compression curves are derived as a function of internal folding. Based on the experimental observations, analysis has been carried out to find the progressive crushing load and crush length in a cycle of round and conical shells. The shells are infilled with polyurethane foam and subjected to axial compression. The effect of foam on the crushing behaviour is also studied. Conical shells of different cone angles varied from 8.5" to 45" and the effect of cone angle on the crushing mode of the conical shells has been studied. Also, a comparative study of metallic and composite shells has been carried out based on the deformation and energy absorption characteristics. The different parameters considered for analysis include effective crushing length and total energy absorbed during the crushing process and the Euler buckling length in metallic shells

Sociobiological Control of Plasmid copy number

Background:&#xd;&#xa;All known mechanisms and genes responsible for the regulation of plasmid replication lie with the plasmid rather than the chromosome. It is possible therefore that there can be copy-up mutants. Copy-up mutants will have within host selective advantage. This would eventually result into instability of bacteria-plasmid association. In spite of this possibility low copy number plasmids appear to exist stably in host populations. We examined this paradox using a computer simulation model.&#xd;&#xa;&#xd;&#xa;Model:&#xd;&#xa;Our multilevel selection model assumes a wild type with tightly regulated replication to ensure low copy number. A mutant with slightly relaxed replication regulation can act as a &#x201c;cheater&#x201d; or &#x201c;selfish&#x201d; plasmid and can enjoy a greater within-host-fitness. However the host of a cheater plasmid has to pay a greater cost. As a result, in host level competition, host cell with low copy number plasmid has a greater fitness. Furthermore, another mutant that has lost the genes required for conjugation was introduced in the model. The non-conjugal mutant was assumed to undergo conjugal transfer in the presence of another conjugal plasmid in the host cell.&#xd;&#xa;&#xd;&#xa;Results:&#xd;&#xa;The simulatons showed that if the cost of carrying a plasmid was low, the copy-up mutant could drive the wild type to extinction or very low frequencies. Consequently, another mutant with a higher copy number could invade the first invader. This process could result into an increasing copy number. However above a certain copy number within-host selection was overcompensated by host level selection leading to a rock-paper-scissor (RPS) like situation. The RPS situation allowed the coexistence of high and low copy number plasmids. The non-conjugal &#x201c;hypercheaters&#x201d; could further arrest the copy numbers to a substantially lower level.&#xd;&#xa;&#xd;&#xa;Conclusions:&#xd;&#xa;These sociobiological interactions might explain the stability of copy numbers better than molecular mechanisms of replication regulation alone

Electrochemistry at nanoscale electrodes : individual single-walled carbon nanotubes (SWNTs) and SWNT-templated metal nanowires

Individual nanowires (NWs) and native single-walled carbon nanotubes (SWNTs) can be readily used as well-defined nanoscale electrodes (NSEs) for voltammetric analysis. Here, the simple photolithography-free fabrication of submillimeter long Au, Pt, and Pd NWs, with sub-100 nm heights, by templated electrodeposition onto ultralong flow-aligned SWNTs is demonstrated. Both individual Au NWs and SWNTs are employed as NSEs for electron-transfer (ET) kinetic quantification, using cyclic voltammetry (CV), in conjunction with a microcapillary-based electrochemical method. A small capillary with internal diameter in the range 30–70 μm, filled with solution containing a redox-active mediator (FcTMA+ ((trimethylammonium)methylferrocene), Fe(CN)64–, or hydrazine) is positioned above the NSE, so that the solution meniscus completes an electrochemical cell. A 3D finite-element model, faithfully reproducing the experimental geometry, is used to both analyze the experimental CVs and derive the rate of heterogeneous ET, using Butler–Volmer kinetics. For a 70 nm height Au NW, intrinsic rate constants, k0, up to ca. 1 cm s–1 can be resolved. Using the same experimental configuration the electrochemistry of individual SWNTs can also be accessed. For FcTMA+/2+ electrolysis the simulated ET kinetic parameters yield very fast ET kinetics (k0 > 2 ± 1 cm s–1). Some deviation between the experimental voltammetry and the idealized model is noted, suggesting that double-layer effects may influence ET at the nanoscale

Ballistic Impact on Glass/Epoxy Composite Laminates

Glass/epoxy composite laminates are subjected to impact loading and the energy absorbing capacity of the laminates is studied. In the present study, laminates with four different orientations and thickness values are considered. Analytical study is carried out based on energy method and results are compared with FE results obtained from Abaqus/Explicit software. Results obtained from the analytical methods are showing good agreement with the FE results. It is found that cross-ply laminates are most efficient in ballistic resistance when compared with the laminates of other orientations. It is also noticed that the energy absorbing capacity is decreasing with increase in velocity of the projectile for a given lay-up and thickness value.Defence Science Journal, Vol. 64, No. 4, July 2014, pp. 393-399, DOI:http://dx.doi.org/10.14429/dsj.64.3882