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Graphene oxide (GO) is a carbon-based material, which is one atom thick sheet of graphite. The nanofillers have exceptional stiffness and strength owing to the presence of two-dimensional graphene backbone. Especially owing to this reason, nanocomposites have been developed using GO for several applications. This review article explores the synthesis of GO from flake graphite. Main emphasis has been afforded on the preparation and characterization of GO nanocomposites, utilizing various industrial polymers for wide application in aerospace, biomedical, military, supercapacitors, electrical, sensor, and so on. Morphological characterization exploring the interaction and extent of dispersion of GO nanosheets in the polymer matrices is extensively accounted. From the reports, it is clear that exfoliation and strong interaction of GO tremendously improved the physical, mechanical, thermal, electrochemical, biocompatibility, and tribological properties of the added polymer. POLYM. COMPOS., 35:2297–2310, 2014. © 2014 Society of Plastics Engineers

Cyclin-dependent kinase-5 (CDK5), a unique CDK family member, is active primarily in the central nervous system (CNS). Previous studies suggest that CDK5 is proapoptotic and contributes to tau hyperphosphorylation and neurodegeneration in Alzheimer's disease. The objective of this study was to examine CDK5 effects on apoptotic progression and tau phosphorylation. Immortalized embryonic mouse brain cortical cells were used to establish a stable cell line that overexpressed wild-type human tau. In these studies, thapsigargin, which induces endoplasmic reticulum stress and can cause accumulation of misfolded proteins, was used to induce apoptosis. Caspase-3 activity and poly-(ADP-ribose)-polymerase (PARP) cleavage, as measures of apoptosis, were significantly increased 24 and 48 hr after thapsigargin treatment, and these events were unaffected by tau expression. Although transient coexpression of CDK5 and its activator, p25, increased CDK5 activity greater than tenfold, increases in caspase-3 activity in response to thapsigargin treatment were unaffected by the presence of CDK5/p25. Tau phosphorylation at the PHF-1 epitope, but not the Tau-1 epitope, was increased significantly in CDK5/p25-transfected cells compared to cells transfected with dominant negative CDK5 (DNCDK5). The PHF-1 epitope remained phosphorylated until 48 hr after thapsigargin treatment in the CDK5/p25-transfected cells. Over the course of apoptosis in this model, phosphorylation of the Tau-1 epitope was unaffected in cells transfected with DNCDK5, vector, or CDK5/p25. In summary, these results demonstrate that CDK5 does not have a significant impact on tau phosphorylation and thapsigargin-induced apoptosis in this neuronal cell model.

Cyclin dependent kinase 5 (Cdk5) is a proline-direct protein kinase that is most active in the CNS, and has been implicated as a contributing factor in certain neurodegenerative diseases. Further, there is evidence to suggest that Cdk5 may facilitate the progression of apoptosis. However, the mechanisms involved have not been elucidated. The tumor suppressor protein p53, a transcription factor that is regulated by phosphorylation, increases the expression of genes that control growth arrest or cell death. To understand how Cdk5 could facilitate apoptosis, the effects of Cdk5 on p53 activity were examined. In the present study it is shown that in apoptotic PC12 cells the levels of p53 and Cdk5 increase concomitantly. Further, Cdk5/p25 effectively phosphorylates recombinant p53 in vitro. Transient transfection of Cdk5/p25 into cells results in an increase in p53 levels, as well as the expression of the p53-responsive genes p21 and Bax. Furthermore, evidence is provided that increased Cdk5 activity increases p53 transcriptional activity significantly, suggesting that p53 is modulated in situ by Cdk5. This is the first demonstration that p53 is a substrate of Cdk5, and that Cdk5 can modulate p53 levels and activity.

Aortopathy is a subclinical disease characterized by aortic dilation, which can result in aortic dissection and/or aortic aneurysm. Hallmarks of aortopathy include vascular smooth muscle cell (VSMC...

The effects of an oxidative insult on cell survival and tau metabolism were investigated in human neuroblastoma SH-SY5Y cells. In this treatment paradigm cells were exposed to the membrane permeant oxidant tert-butylhydroperoxide (tBHP) for 40 min, returned to fresh media and cell survival/death was monitored during the post-treatment period. Cell viability decreased significantly by 6 hr after tBHP exposure, and by 24 hr lactate dehydrogenase (LDH) release was 40.1 +/- 8.8% in tBHP treated cells compared to 8.1 +/- 4.7% in control cells. This oxidative stress paradigm also resulted in significant activation of caspase-3 by 2 hr post-treatment and nuclear apoptotic morphology. Furthermore, tBHP treatment also resulted in delayed tau proteolysis that was first evident 2 hr post-treatment. Treatment of the cells with the general caspase inhibitor Boc-Asp(OMe)-Fluoromethylketone (BAF) completely inhibited caspase-3 activation in response to tBHP, and delayed, but did not prevent cell death. BAF treatment also decreased tau proteolysis. In vitro, recombinant tau was readily proteolyzed by active recombinant caspase-3 into a stable breakdown product. Further tau in the cell lysates was cleaved by active recombinant caspase-3 at a rate, and to an extent similar to that observed for the well-established caspase-3 substrate poly(ADP-ribose)polymerase (PARP). These results suggest that oxidative stress-induced cell death occurs through both caspase-dependent and-independent pathways, and that tau is likely an in situ substrate of caspase-3.

Polynomial and polynomial exponential models of order one to four were tried to describe crop growth in two maize cultivars viz., Deccan hybrid and Deccan 101 of an agronomic trial conducted at the University of Agricultural Sciences, Bangalore, on alfisols. Relative growth rate (RGR) of classical and functional methods was compared. Models performance was assessed based on r2, χ2 residuals sum of squares (RSS), root mean standard deviation (RMSD) and presence or absence of heteroscedasticity in models' predictions. In the cultivars, polynomials of order three and four in Deccan hybrid and cubic polynomial in Deccan 101 simulated dry matter production (DMP) by 99.5 % and showed good distribution of error variance over the observed DMP. The RGR from the third and fourth degree polynomials in both the cultivars was comparable to the classical method and explained better during post-silking period. Polynomial exponentials predicted very low RGR. Between cultivars, Deccan 101 showed higher RGR during 45–80 days after sowing and contributed significantly more to final DMP.

Various mathematical models were fitted to describe total dry matter production (DMP) and cob weight in two maize cultivars viz., Deccan hybrid and Deccan 101. The data on periodical crop growth from an agronomic trial conducted at the University of Agricultural Sciences, Bangalore, were used to predict crop and cob growth empirically. In cv. Deccan hybrid, Gompertz followed by Richards models predicted DMP by 99 % nearer to the actual values. Whereas in cv. Deccan 101, Richards-cum-logistic for vegetative-cum-reproductive stage simulated DMP with R2 of 92 to 99 %. Further, cob growth was estimated realistically with high R2 of 97 to 98 % using empirical models of logistic followed by Richards in cv. Deccan 101 and Richards followed by Gompertz in cv. Deccan hybrid. Comparing the empirical models in describing DMP and cob growth, the models showing higher predictions in DMP also estimated cob growth meaningfully in both the cultivars, indicating similarity in growth functions.

Allometric relationship (W1=αW2β, where α and β are the parameters) was fitted among growth components in two maize cultivars viz., Decani hybrid and Deccan 101 in order to obtain estimates of other components of the plant system which are time consuming measurements. The results of the agronomic field trial conducted at the University of Agricultural Sciences, Bangalore were used. This model's predictability was compared with linear regression model. In both the cultivars, allometric model using leaf area (LA - W2.) and leaf dry matter (LDM - W2) simulated total dry matter production (DMP - W2) by 79 to 98 % of actual values. Further allometric model fitted well to predict stem dry matter by 91 to 93 % using LDM and LA 89 to 92 % using LDW. Whereas linear regression model estimated total DMP by 95 to 96 % using cob dry matter. In case of LDM - LA association, linear regression model was found to be the best than other model. The leaf area decreased after silking in both the cultivars and the ratio of growth rates of DMP – LA (β2) was negative. Between cultivars, cv. Deccan 101 had higher R2 values in most of the relationships than cv. Deccan hybrid indicating the varietal difference.

Presented in this paper is a finite element method for the analysis of nonlinear oscillations which exhibit periodic response. The basic idea of the method is to recast the initial value problem as a boundary value problem in which the domain (that is, period) may be unknown. We apply the method to study the free response of the conservative oscillator u + mu + ϵf(u)=0, where m is either − 1, 0 or 1, f(u) is an odd nonlinear function, and ϵ need not be small. The harmonically forced case, u + mu + ϵf(u) = Psin Ωt, is also considered, and it is shown that the superharmonic response can be efficiently calculated using this technique.

Knowledge of plankton biogeography for the Indian and adjacent seas is necessary for an understanding of the regional characteristics and changes in the plankton composition. Some of the plankters will serve as good biogeographical indicator species. Some phytoplankters and tintinnids among zooplankton are promising for use as such labels for the presence of different waters in the Porto Novo (Coromandel coast, Bay of Bengal) region. A biogeographical classification of the local phytoplankton and peculiarities in the distribution of some rare tintinnids occurring there are discussed.

The phytoplankton species composition and community structure were studied at two stations in the Vellar estuary from January to December, 1983. A total of 117 species of phytoplankton belonging to various groups, namely diatoms (90), dinoflagellates (21), Chlorophyceae (3), Cyanophyceae (2) and silicoflagellates (1) were observed during the study. The species diversity, richness and evenness values varied from 0.7 to 4.2 units/individual, 0.9 to 5.7 and 0.19 to 0.75 respectively. Dominance index values varied between 32.6 and 96.4 during the study period.

Studies were made to examine the applicability of a common leaf product constant (K-constant × length × width), for estimating the area of single leaf and it was found that the same constant was applicable for the 3 sorghum genotypes (Sorghum bicolor L Moench) studied (K=0.71). Adaptability of the common leaf product constant for individual leaves according to its position in the plant was also tested by regression analysis, and the same constant was found to be applicable in most cases. Because complete measurement of all leaves of a plant in field trials is time-consuming and involves prohibitive labor input, the most representative leaf was identified through correlation studies to use it in working out the leaf area index. The largest leaf was found to be the most representative. This representative leaf differed with genotype, depending upon total leaf number. An appropriate factor to work out leaf area of the whole plant from a single leaf was determined. This leaf area factor was found to vary from 4.106 to 5.873 among the sorghum genotypes