A Fluorescence Assay for DNA with Covalently Linked Complementary Sequences

1972 ◽  
Vol 50 (2) ◽  
pp. 210-216 ◽  
Author(s):  
A. Richard Morgan ◽  
Verner Paetkau
Keyword(s):  
Ethidium Bromide ◽  
Fluorescence Enhancement ◽  
Nucleation Site ◽  
Heat Denaturation ◽  
Heating And Cooling ◽  
Physical Measurements ◽  
Complementary Sequences ◽  
Naturally Occurring ◽  
Nucleation Sites ◽  
Covalently Linked

An assay which measures polydeoxyribonucleates containing covalently linked complementary sequences is described. It is based on the fluorescence enhancement of ethidium bromide bound to bihelical polydeoxyribonucleates. This dependence of fluorescence enhancement upon bihelicity has been further documented. Synthetic, defined polymers, such as d(A)n∙d(T)n, d(AT)n∙d(AT)n, d(TC)n∙d(GA)n, and d(TTG)n∙d(CAA)n, have been studied, as well as naturally occurring DNAs. At moderate ionic strengths, the synthetic polymers will re-anneal following heat denaturation. Their facility to renature is due to the self-complementarity between strands throughout their lengths. This facility is lost at very low ionic strengths (Γ/2 < 0.003 M), where ionic repulsion prevents the formation of "nucleation" sites for annealing. However, a covalent linkage between strands provides a nucleation site for renaturation. The fluorescence seen with ethidium bromide after heating and cooling such polymers is then a measure of DNA which has covalently linked complementary sequences. By this assay, natural DNAs appear to contain short, relatively unstable bihelical regions following heat denaturation and cooling, in agreement with models based on other physical measurements.

Proton Induced Structuring of a Photostructurable Glass

2002 ◽  
Vol 739 ◽  
Author(s):  
Meg Abraham ◽  
Inmaculada Gomez-Morilla ◽  
Mike Marsh ◽  
Geoff Grime
Keyword(s):  
Three Dimensional ◽  
Particle Beam ◽  
Nucleation Site ◽  
Buried Structures ◽  
Corning Glass ◽  
Nucleation Sites ◽  
Initial Nucleation ◽  
Similar Product ◽  
Photon Process ◽  
Meta Silicate

ABSTRACTThe use of photons to create intricate three-dimensional and buried structures [1] in photo-structurable glass has been well demonstrated at several institutions [2]. In these instances the glass used whether it be Foturan™, made by the Schott Group or a similar product made by Corning Glass, forms a silver nucleation sites on exposure to intense UV laser light via a two-photon process. Subsequent annealing causes a localized crystal growth to form a meta-silicate phase which can be etched in dilute hydrofluoric acid at rates of 20 to 50 times that of the unprocessed glass. The same formulation of glass can be “exposed” using a particle beam to create the nucleation site. In the case of particle beam exposure, experiments have shown that the mechanisms that cause this initial nucleation and eventual stochiometric transformation, after annealing, depend largely on the beam energy.

scholarly journals Hydrolysis of a naturally occurring β-glucoside by a broad-specificity β-glucosidase from liver

1986 ◽  
Vol 237 (2) ◽  
pp. 469-476 ◽  
Author(s):  
K L LaMarco ◽  
R H Glew
Keyword(s):  
Guinea Pig ◽  
Competitive Inhibitor ◽  
Heat Denaturation ◽  
Pig Liver ◽  
Naturally Occurring ◽  
Aryl Glycosides ◽  
Beta Glucosidase ◽  
Hydrolysis Of ◽  
Guinea Pig Liver ◽  
Broad Specificity

We have isolated from guinea-pig liver a broad-specificity beta-glucosidase of unknown function that utilizes as its substrate non-physiological aryl glycosides (e.g. 4-methylumbelliferyl beta-D-glucopyranoside, p-nitrophenyl beta-D-glucopyranoside). The present paper documents that this enzyme can be inhibited by various naturally occurring glycosides, including L-picein, dhurrin and glucocheirolin. In addition, L-picein, which acts as a competitive inhibitor of the broad-specificity beta-glucosidase (Ki 0.65 mM), is also a substrate for this enzyme (Km 0.63 mM; Vmax. 277,000 units/mg). Heat-denaturation, kinetic competition studies, chromatographic properties and pH optima all argue strongly that the broad-specificity beta-glucosidase is responsible for the hydrolysis of both the non-physiological aryl glycosides and L-picein. This paper demonstrates that beta-glucosidase can catalyse the hydrolysis of a natural glycoside, and may provide a key to understanding the function of this enigmatic enzyme. A possible role in the metabolism of xenobiotic compounds is discussed.

Carbon Black and Fullerenes: New Discoveries in Early Formation Mechanisms and Nucleation

2000 ◽  
Vol 73 (5) ◽  
pp. 875-888 ◽  
Author(s):  
M. Pontier Johnson ◽  
R. W. Locke ◽  
J. B. Donnet ◽  
T. K. Wang ◽  
C. C. Wang ◽  
...  
Keyword(s):  
Carbon Black ◽  
Mass Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Nucleation Site ◽  
Formation Mechanisms ◽  
Clear Understanding ◽  
Transmission Electron ◽  
Nucleation Sites ◽  
Buckminster Fullerene ◽  
Secondary Ion

Abstract Recent studies on the formation of carbon black have resulted in the previously unreported finding of buckminster-fullerene, C60, in trace quantities in the toluene extractable materials. High-resolution transmission electron microscopy (HRTEM) experiments indicate the molecule may be functioning as a nucleation site in the formation of primary particles of carbon black. Time-of-flight secondary ion mass spectroscopy (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) provided the surface chemical analysis of conventional and experimental carbon blacks. The toluene extracts represented the precursor compounds present in the gaseous phase at the time of quench. The extracts were analyzed by Fourier transform infrared (FTIR) spectroscopy, liquid chromatography (LC)/mass spectroscopy (MS) and elemental composition. The data, taken as a whole, have led to a more clear understanding of the competitive chemical pathways occurring during the inception and nucleation of a primary particle of carbon black. Direct observation of nucleation sites and types are possible with HRTEM analysis.

scholarly journals Ice nucleation efficiency of clay minerals in the immersion mode

2012 ◽  
Vol 12 (13) ◽  
pp. 5859-5878 ◽  
Author(s):  
V. Pinti ◽  
C. Marcolli ◽  
B. Zobrist ◽  
C. R. Hoyle ◽  
T. Peter
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Differential Scanning Calorimeter ◽  
Pure Water ◽  
Nucleation Site ◽  
Ice Nucleation ◽  
Nucleation Sites ◽  
The One ◽  
Site Classes

Abstract. Emulsion and bulk freezing experiments were performed to investigate immersion ice nucleation on clay minerals in pure water, using various kaolinites, montmorillonites, illites as well as natural dust from the Hoggar Mountains in the Saharan region. Differential scanning calorimeter measurements were performed on three different kaolinites (KGa-1b, KGa-2 and K-SA), two illites (Illite NX and Illite SE) and four natural and acid-treated montmorillonites (SWy-2, STx-1b, KSF and K-10). The emulsion experiments provide information on the average freezing behaviour characterized by the average nucleation sites. These experiments revealed one to sometimes two distinct heterogeneous freezing peaks, which suggest the presence of a low number of qualitatively distinct average nucleation site classes. We refer to the peak at the lowest temperature as "standard peak" and to the one occurring in only some clay mineral types at higher temperatures as "special peak". Conversely, freezing in bulk samples is not initiated by the average nucleation sites, but by a very low number of "best sites". The kaolinites and montmorillonites showed quite narrow standard peaks with onset temperatures 238 K

Interaction of the Nucleation Processes Occurring at Adjacent Nucleation Sites

1993 ◽  
Vol 115 (4) ◽  
pp. 955-962 ◽  
Author(s):  
R. L. Judd ◽  
A. Chopra
Keyword(s):  
Experimental Investigation ◽  
Nucleation Site ◽  
Experimental Investigations ◽  
Nucleation Sites

An experimental investigation to explore the interaction between bubbles forming at adjacent nucleation sites is presented. The results obtained are consistent with the results of Calka’s and Knowles’ experimental investigations and confirm that nucleation site activation/deactivation, whereby a bubble growing at a nucleation site is able to promote/hinder the formation of a bubble at an adjacent nucleation site by depositing/displacing a vapor nucleus in the nucleation cavity, is instrumental in determining how a bubble forming at a nucleation site influences the nucleation of the subsequent bubble at an adjacent nucleation site.

Further Developments of Dropwise Condensation Theory

1979 ◽  
Vol 101 (4) ◽  
pp. 603-611 ◽  
Author(s):  
H. Tanaka
Keyword(s):  
Critical Size ◽  
Nucleation Site ◽  
Dropwise Condensation ◽  
Condensation Coefficient ◽  
Characteristic Parameters ◽  
Nusselt Numbers ◽  
Site Density ◽  
Nucleation Sites ◽  
Basic Equations ◽  
Nucleation Site Density

The high rates of heat transfer of dropwise condensation as well as its limits are explained on the basis of the behaviors of submicroscopic active drops. The expression for the substantial growth rate of a single drop valid down to the thermodynamic critical size is incorporated into a set of basic equations from [8] whose capability to describe the process of coalescence and growth of drops in dropwise condensation has been demonstrated in [9]. Consideration of the nondimensionalized forms of the basic equations with the aid of numerical analysis results in an expression of the Nusselt number for dropwise condensation in terms of a few characteristic parameters. Comparison of the predicted Nusselt numbers with available experimental data suggests that the condensation coefficient of water is around 0.2 provided the nucleation site density is infinitely high. Otherwise, if the condensation coefficient should be unity, we have to accept that the nucleation sites are fairly scattered.

Selective Nucleation and Growth of Large Grain Polycrystalline GaAs

2005 ◽  
Vol 870 ◽  
Author(s):  
C. G. Allen ◽  
J. D. Beach ◽  
A. A. Khandekar ◽  
J. C. Dorr ◽  
C. Veauvy ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Nucleation Site ◽  
Site Formation ◽  
Organic Chemical ◽  
Subsequent Work ◽  
Nucleation Sites ◽  
Initial Nucleation ◽  
Electrochemically Deposited ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

AbstractA method for depositing large grained polycrystalline GaAs on lattice mismatched substrates through controlled nucleation and selective growth is presented. The process was developed on Si wafers. Nucleation site formation began with nanolithography to create submicron holes in photoresist on Si. Ga metal was electrochemically deposited into the holes. Subsequent arsine anneals converted the gallium deposits into GaAs. Photoluminescence and electron diffraction verified conversion to GaAs. Metal-Organic Chemical Vapor Deposition (MOCVD) enlarged the seed crystals to coalescence without creating additional nucleation sites within the patterned field. Having successfully demonstrated the approach, subsequent work has been directed at lower cost, alternative ways to define initial nucleation sites, such as, microcontact lithography and direct decomposition of triethyl gallium to Ga metal in the MOCVD chamber.

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