Isolation and characterization of DNA polymerase epsilon from the silk glands of Bombyx mori

The silk gland of Bombyx mori, an endomitotically replicative tissue shows high levels of DNA polymerases alpha, delta, and epsilon activities. The ratio of polymerase alpha to that of delta plus epsilon is maintained at 1.1 to 1.3 in both the posterior and middle silk glands for the entire duration of late larval development. The three activities copurify in the initial stages of fractionation through phosphocellulose and DE52 but polymerase alpha gets resolved from the others on hydroxylapatite column. Separation between polymerase delta and epsilon is achieved by chromatography on QAE-Sephadex. DNA polymerase epsilon is a heterodimer comprising of 215- and 42-kDa subunits. The activity is maximum at pH 6.5 and the Km values for dNTPs vary between 3-9 microM. The enzyme possesses an intrinsically associated exonuclease activity which functions in the mismatch repair during DNA synthesis. Both polymerase and 3'-->5' exonuclease activities are associated with the 215-kDa subunit. By itself, DNA polymerase epsilon is processive and the catalytic activity is not enhanced by externally added bPCNA (Bombyx-proliferating cell nuclear antigen, an auxiliary protein for DNA polymerase delta). The enzyme resembles polymerase delta in having the exonuclease activity and in its response to aphidicolin or substrate analogs, but could be distinguished from the latter by its lack of response to the bPCNA and sensitivity to dimethyl sulfoxide. The two enzymes show partial immunological cross-reactivity with each other but no immunological relatedness to polymerase alpha. The absence of the repair enzyme DNA polymerase beta and the presence of substantial levels of polymerase epsilon in the silk glands suggest a possible role for the latter in DNA repair in that tissue.

Structural characterization of gel-grown neodymium copper oxalate single crystals

Sparingly soluble neodymium copper oxalate (NCO) single crystals were grown by gel method, by the diffusion of a mixture of neodymium nitrate and cupric nitrate into the set gel containing oxalic acid. Tabular crystal, revealing well-defined dissolution figures has been recorded. X-ray diffraction studies of the powdered sample reveal that NCO is crystalline. Infrared absorption spectrum confirmed the formation of oxalato complex with water of crystallization, while energy dispersive X-ray analysis established the presence of neodymium dominant over copper in the sample. X-ray photoelectron spectroscopic studies established the presence of Nd and Cu in oxide states besides (C2O4)(2-) oxalate group. The intensities of Nd (3d(5/2)) and Cu (2p(3/2)) peaks measured in terms of maximum photoelectron count rates also revealed the presence of Nd in predominance. The inductively coupled plasma analysis supports the EDAX and XPS data by the estimation of neodymium percentage by weight to that of copper present in the NCO sample. On the basis of these findings, an empirical structure for NCO has been proposed. The implications are discussed.

The mean and turbulence structure simulation of the monsoon trough boundary layer using a one-dimensional model with e-l and e-epsilon closures

An attempt has been made here to study the sensitivity of the mean and the turbulence structure of the monsoon trough boundary layer to the choice of the constants in the dissipation equation for two stations Delhi and Calcutta, using one-dimensional atmospheric boundary layer model with e-epsilon turbulence closure. An analytical discussion of the problems associated with the constants of the dissipation equation is presented. It is shown here that the choice of the constants in the dissipation equation is quite crucial and the turbulence structure is very sensitive to these constants. The modification of the dissipation equation adopted by earlier studies, that is, approximating the Tke generation (due to shear and buoyancy production) in the epsilon-equation by max (shear production, shear + buoyancy production), can be avoided by a suitable choice of the constants suggested here. The observed turbulence structure is better simulated with these constants. The turbulence structure simulation with the constants recommended by Aupoix et al (1989) (which are interactive in time) for the monsoon region is shown to be qualitatively similar to the simulation obtained with the constants suggested here, thus implying that no universal constants exist to regulate dissipation rate. Simulations of the mean structure show little sensitivity to the type of the closure parameterization between e-l and e-epsilon closures. However the turbulence structure simulation with e-epsilon closure is far better compared to the e-l model simulations. The model simulations of temperature profiles compare quite well with the observations whenever the boundary layer is well mixed (neutral) or unstable. However the models are not able to simulate the nocturnal boundary layer (stable) temperature profiles. Moisture profiles are simulated reasonably better. With one-dimensional models, capturing observed wind variations is not up to the mark.

Effect of neodymium (Nd) doping on the dielectric and ferroelectric characteristics of sol-gel derived lead zirconate titanate (53/47) thin films

The results of the studies on the effect of rare earth Nd doping on the phase formation behavior and electrical properties of sol-gel derived Pb-1.05(Zr0.53Ti0.47)O-3 (PZT) thin films are presented. The perovskite phase is obtained up to 5 at. % doping and beyond that pyrochlore phase was found to coexist with the perovskite phase in all the films. The transition temperature of undoped lead zirconate titanate (PZT) film was found to be reduced with Nd doping. The Nd doped films also exhibited typical relaxor-type behavior and a diffuse phase transition, similar to that observed in relaxor materials. The introduction of Nd into the PZT lattice probably introduces disorder in the B site of ABO(3) lattice, which causes the observed dielectric relaxation. Efforts were made to isolate the irreversible component contributions in low field dielectric and high field polarization switching behavior. (C) 2001 American Institute of Physics.

A k-epsilon model for turbulent weld pool convection in gas metal arc welding process

In this paper, we present a modified k - epsilon model capable of addressing turbulent weld-pool convection in a GMAW process, taking into account the morphology of the phase change interface during a Gas Metal Arc Welding (GMAW) process. A three-dimensional turbulence mathematical model has been developed to study the heat transfer and fluid flow within the weld pool by considering the combined effect of three driving forces, viz., buoyancy, Lorentz force and surface tension (Marangoni convection). Mass and energy transports by the droplets are considered through the thermal analysis of the electrode. The falling droplet's heat addition to the molten pool is considered to be a volumetric heat source distributed in an imaginary cylindrical cavity ("cavity model") within the weld pool. This nature of heat source distribution takes into account the momentum and the thermal, energy of the falling droplets. The numerically predicted weld pool dimensions both from turbulence and laminar models are then compared with the experimental post-weld results sectioned across the weld axis. The above comparison enables us to analyze the overall effects of turbulent convection on the nature of heat and fluid flow and hence on the weld pool shape/size during the arc welding processes.

Amine-functionalized multiwall carbon nanotubes impart osteoinductive and bactericidal properties in poly(epsilon-caprolactone) composites

Poly(epsilon-caprolactone) (PCL) is an aliphatic polyester widely used for biomedical applications but lacks the mechanical properties desired for many load-bearing orthopedic applications. The objective of this study was to prepare and characterize PCL composites incorporating multiwall carbon nanotubes (MWNTs) with different surface functional groups. PCL composites were prepared by melt-mixing with three different types of MWNTs: pristine (pMWNT), amine functionalized (aMWNT), and carboxyl functionalized (cMWNT). Melt rheology and scanning electron microscopy indicated good dispersion of the nanotubes in the matrix. Tensile strength and elastic modulus of the polymer was significantly increased by the incorporation of MWNTs and further enhanced by favorable interactions between PCL and aMWNTs. Thermal analysis revealed that MWNTs act as heterogeneous nucleation sites for crystallization of PCL and increase polymer crystallinity. Incorporation of functionalized MWNTs increased the surface water wettability of PCL. Osteoblast proliferation and differentiation was significantly enhanced on functionalized composites. aMWNT composites also exhibited the best bactericidal response. This study demonstrates that surface functionalization of MWNTs profoundly influences the properties of PCL and amine-functionalization offers the optimal combination of mechanical properties, osteogenesis and antimicrobial response. These results have important implications for designing nanocomposites for use in orthopedics.

Small strong epsilon nets

Let P be a set of n points in R-d. A point x is said to be a centerpoint of P if x is contained in every convex object that contains more than dn/d+1 points of P. We call a point x a strong centerpoint for a family of objects C if x is an element of P is contained in every object C is an element of C that contains more than a constant fraction of points of P. A strong centerpoint does not exist even for halfspaces in R-2. We prove that a strong centerpoint exists for axis-parallel boxes in Rd and give exact bounds. We then extend this to small strong epsilon-nets in the plane. Let epsilon(S)(i) represent the smallest real number in 0, 1] such that there exists an epsilon(S)(i)-net of size i with respect to S. We prove upper and lower bounds for epsilon(S)(i) where S is the family of axis-parallel rectangles, halfspaces and disks. (C) 2014 Elsevier B.V. All rights reserved.

epsilon-expansions near three dimensions from conformal field theory

We formally extend the CFT techniques introduced in arXiv: 1505.00963, to phi(2d0/d0-2) theory in d = d(0) dimensions and use it to compute anomalous dimensions near d(0) = 3, 4 in a unified manner. We also do a similar analysis of the O(N) model in three dimensions by developing a recursive combinatorial approach for OPE contractions. Our results match precisely with low loop perturbative computations. Finally, using 3-point correlators in the CFT, we comment on why the phi(3) theory in d(0) = 6 is qualitatively different.

Mitochondrial selectivity and remarkable photocytotoxicity of a ferrocenyl neodymium(III) complex of terpyridine and curcumin in cancer cells

A series of four novel neodymium(III) complexes of the formulation Nd(R-tpy)(O-O)(NO3)(2)] (1-4), where R-tpy is 4'-phenyl-2,2': 6', 2''-terpyridine (Ph-tpy; 1, 2) and 4'-ferrocenyl-2,2': 6', 2''-terpyridine (Fc-tpy; 3, 4); O-O is the conjugate base of acetylacetone (Hacac; 1, 3) or curcumin (Hcurc; 2, 4), are synthesized and characterized. The single crystal structure of 1 shows that the complex is a discrete mononuclear species with the Nd(III) centre in a nine coordinate environment provided by a set of O6N3 donor atoms. Complexes 1 and 3 having the simple acac ligand are prepared as control compounds. Complex 4, possessing an appended ferrocenyl (Fc) and the curcumin moiety, is remarkably photocytotoxic to HeLa and MCF-7 cancer cells in visible light giving respective IC50 values of 0.7 mu M and 2.1 mu M while being significantly less toxic to MCF-10A normal cells (IC50 = 34 mu M) and in the dark (IC50 > 50 mu M). The phenyl appended complex 2, lacking a ferrocenyl moiety, is significantly less toxic to both the cell lines when compared with 4. Complexes 1 and 3, lacking the photoactive curcumin moiety, do not show any apparent toxicity both in light and in the dark. The cell death is apoptotic in nature and is mediated by the light-induced formation of reactive oxygen species (ROS). Fluorescence imaging experiment with HeLa cells reveals mitochondrial accumulation of complex 4 within 4 h of incubation. The complexes bind to calf thymus (ct) DNA with moderate affinity giving K-b values in the range of 10(4)-10(5) M-1. The curcumin complexes 2 and 4 cleave plasmid supercoiled DNA to its nicked circular form in visible light via O-1(2) and (OH)-O-center dot pathways. The presence of the ferrocenyl moiety is likely to be responsible for the enhanced cellular uptake and photocytotoxicity of complex 4. Thus, the mitochondria targeting complex 4, being remarkably cytotoxic in light but non-toxic in the dark and to normal cells, is a potential candidate for photochemotherapeutic applications.

Gamma -> Epsilon Martensite Transformation and Twinning Deformation in fcc Cobalt During Surface Mechanical Attrition Treatment

The deformation microstructure of face-centered cubic cobalt subjected to surface mechanical attrition treatment was studied as a function of strain levels. Strain-induced gamma --> epsilon transformation and twinning deformation were evidenced by transmission electron microscopy and were found to progress continuously in ultrafine and nanocrystalline grains as the strain increased.

Completions of epsilon-dense partial Latin squares

A classical question in combinatorics is the following: given a partial Latin square $P$, when can we complete $P$ to a Latin square $L$? In this paper, we investigate the class of textbf{$epsilon$-dense partial Latin squares}: partial Latin squares in which each symbol, row, and column contains no more than $epsilon n$-many nonblank cells. Based on a conjecture of Nash-Williams, Daykin and H"aggkvist conjectured that all $frac{1}{4}$-dense partial Latin squares are completable. In this paper, we will discuss the proof methods and results used in previous attempts to resolve this conjecture, introduce a novel technique derived from a paper by Jacobson and Matthews on generating random Latin squares, and use this novel technique to study $ epsilon$-dense partial Latin squares that contain no more than $delta n^2$ filled cells in total.

In Chapter 2, we construct completions for all $ epsilon$-dense partial Latin squares containing no more than $delta n^2$ filled cells in total, given that $epsilon < frac{1}{12}, delta < frac{ left(1-12epsilonright)^{2}}{10409}$. In particular, we show that all $9.8 cdot 10^{-5}$-dense partial Latin squares are completable. In Chapter 4, we augment these results by roughly a factor of two using some probabilistic techniques. These results improve prior work by Gustavsson, which required $epsilon = delta leq 10^{-7}$, as well as Chetwynd and H"aggkvist, which required $epsilon = delta = 10^{-5}$, $n$ even and greater than $10^7$.

If we omit the probabilistic techniques noted above, we further show that such completions can always be found in polynomial time. This contrasts a result of Colbourn, which states that completing arbitrary partial Latin squares is an NP-complete task. In Chapter 3, we strengthen Colbourn's result to the claim that completing an arbitrary $left(frac{1}{2} + epsilonright)$-dense partial Latin square is NP-complete, for any $epsilon > 0$.

Colbourn's result hinges heavily on a connection between triangulations of tripartite graphs and Latin squares. Motivated by this, we use our results on Latin squares to prove that any tripartite graph $G = (V_1, V_2, V_3)$ such that begin{itemize} item $|V_1| = |V_2| = |V_3| = n$, item For every vertex $v in V_i$, $deg_+(v) = deg_-(v) geq (1- epsilon)n,$ and item $|E(G)| > (1 - delta)cdot 3n^2$ end{itemize} admits a triangulation, if $epsilon < frac{1}{132}$, $delta < frac{(1 -132epsilon)^2 }{83272}$. In particular, this holds when $epsilon = delta=1.197 cdot 10^{-5}$.

This strengthens results of Gustavsson, which requires $epsilon = delta = 10^{-7}$.

In an unrelated vein, Chapter 6 explores the class of textbf{quasirandom graphs}, a notion first introduced by Chung, Graham and Wilson cite{chung1989quasi} in 1989. Roughly speaking, a sequence of graphs is called "quasirandom"' if it has a number of properties possessed by the random graph, all of which turn out to be equivalent. In this chapter, we study possible extensions of these results to random $k$-edge colorings, and create an analogue of Chung, Graham and Wilson's result for such colorings.

Spectroscopic properties of neodymium doped high silica glass and aluminum codoping effects on the enhancement of fluorescence emission

Nd3+ -codoped and Al3+-Nd3+-codoped high silica glasses have been prepared by sintering nanoporous glasses impregnated with Nd3+ stop and Al3+ ions. The Judd-Ofelt intensity parameters Omega(2,4,6) of Nd3+-doped high silica glasses were obtained and used to analyze aluminum codoping effects. Fluorescence properties of Nd3+-doped high silica glasses strongly depend on the Al3+ concentration. While Nd3+ ion absorption and emission intensities of obviously increase when aluminum is added to Nd3+-doped high silica glasses, fluorescence lifetimes decrease and aluminum codoping has almost no influence on the radiative quantum efficiencies. This indicates that aluminum codoping is responsible for an anti-quenching effect through a local modification of rare-earth environments rather than through physical cluster dispersion.