The reduction of doxorubicin at a mercury electrode and monitoring its interaction with DNA using constant current chronopotentiometry

2009 ◽  
Vol 74 (11-12) ◽  
pp. 1727-1738 ◽  
Author(s):  
Jan Vacek ◽  
Luděk Havran ◽  
Miroslav Fojta
Keyword(s):  
Double Helix ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Ex Situ ◽  
Constant Current ◽  
Adsorbed State ◽  
Electrode Processes ◽  
Dna Double Helix ◽  
First Time

In this report, voltammetry with linear scan and chronopotentiometric stripping (CPS) with constant current were used for the analysis of doxorubicin (DOX) at a hanging mercury drop electrode (HMDE). CPS was used for the study of DOX in situ electrochemical reduction in adsorbed state and for ex situ (adsorptive transfer) analysis of the drug. For the first time, CPS was used to study the reversible reduction of the DOX quinine moiety at –0.45 V (vs Ag|AgCl|3 M KCl) as well as electrode processes giving rise to an irreversible signal around –1.45 V at the HMDE in 0.2 M acetate or Britton–Robinson buffers at different pH values. The dependence of the latter signal on pH revealed involvement of protonation equilibria; however, neither CV nor CPS data confirmed the catalytic character of the electrode reaction previously suggested by other authors. The CPS method was also applied to monitor the DOX interaction with double- (ds) and single-stranded (ss) DNA. In the presence of dsDNA, more pronounced changes in DOX signal intensity were observed, in agreement with a strong intercalation of the DOX redox centre into the DNA double helix.

scholarly journals Cytoplasmic DNA can be detected by RNA fluorescence in situ hybridization

2019 ◽  
Vol 47 (18) ◽  
pp. e109-e109
Author(s):  
Eliraz Greenberg ◽  
Hodaya Hochberg-Laufer ◽  
Shalev Blanga ◽  
Noa Kinor ◽  
Yaron Shav-Tal
Keyword(s):  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Dna Sequences ◽  
Plasmid Dna ◽  
Double Helix ◽  
Rna Molecules ◽  
Rna Fish ◽  
Dna Double Helix ◽  
Intracellular Detection

Abstract Fluorescence in situ hybridization (FISH) can be used for the intracellular detection of DNA or RNA molecules. The detection of DNA sequences by DNA FISH requires the denaturation of the DNA double helix to allow the hybridization of the fluorescent probe with DNA in a single stranded form. These hybridization conditions require high temperature and low pH that can damage RNA, and therefore RNA is not typically detectable by DNA FISH. In contrast, RNA FISH does not require a denaturation step since RNA is single stranded, and therefore DNA molecules are not detectable by RNA FISH. Hence, DNA FISH and RNA FISH are mutually exclusive. In this study, we show that plasmid DNA transiently transfected into cells is readily detectable in the cytoplasm by RNA FISH without need for denaturation, shortly after transfection and for several hours. The plasmids, however, are usually not detectable in the nucleus except when the plasmids are efficiently directed into the nucleus, which may imply a more open packaging state for DNA after transfection. This detection of plasmid DNA in the cytoplasm has implications for RNA FISH experiments and opens a window to study conditions when DNA is present in the cytoplasm.

Polarography of azobenzene and its p-sulphonic acids

1964 ◽  
Vol 17 (10) ◽  
pp. 1085 ◽  
Author(s):  
TM Florence ◽  
YJ Farrar
Keyword(s):  
Ph Effect ◽  
Aqueous Media ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Ammonium Ions ◽  
Current Time ◽  
Electrode Processes ◽  
Ph Values ◽  
Strong Adsorption ◽  
Dropping Mercury Electrode

The behaviour at the dropping mercury electrode of trans-azobenzene and its p-sulphonic acids has been studied by several techniques including d.c., a.c., single sweep, and Kalousek polarography. Current-potential curves recorded at the streaming mercury electrode provided information on the reversibility of the electrode processes, while current-time and electrocapillary curves aided in elucidating the effects of adsorption. The results show that the rate of the electrode reaction of the azo-hydrazo couple is dependent on pH, the minimum rate occurring near pH 9 for azobenzene-4-sulphonic acid in aqueous media. At very low and high pH values, the couple approaches full reversibility at the dropping mercury electrode. This pH effect is apparently due to strong adsorption of both the azo and hydrazo derivatives near the potential of the electrocapillary maximum. Ammonium ions associate with azobenzene-4-sulphonate, and improve the reversibility in intermediate pH regions.

scholarly journals Selección cualitativa del esqueje en la sobrevivencia y desarrollo morfogenético de Vanilla planifolia Andrews

2018 ◽  
Vol 29 (3) ◽  
pp. 616 ◽  
Author(s):  
José Bernal Azofeifa-Bolaños ◽  
German Rivera-Coto ◽  
Amelia Paniagua-Vásquez ◽  
Roberto Cordero-Solórzano
Keyword(s):  
Costa Rica ◽  
In Situ Conservation ◽  
Species Conservation ◽  
Mechanical Damage ◽  
Ex Situ ◽  
Shoot Number ◽  
In The Wild ◽  
First Time ◽  
Integrated Program

In Costa Rica, an urgent ex situ national conservation program for V. planifolia is needed due to the rarity, high risk of extinction in the wild and the economic importance; that places it, as the most profitable orchid worldwide. Due to the lack of research about wild species conservation and the importance to evaluate the agronomic performance of the wild-type relatives, as a strategy to increase the reduced genetic variability, the aim of this research was to evaluate the acclimatization capacity and morphogenetic performance of wild V. planifolia under nursery conditions. The effect of two treatments 1) qualitatively selected cuttings according to their phytosanitary quality, mechanical damage and vigorousness and 2) cuttings without selection, were evaluated. Some growth variables were evaluated: survival rate, weight, length, number of nodes of the new and original shoot; number and weight of the roots The survival of the selected cuttings was greater (60%) than those that were not (45%). The morphogenetic responses of the selected explants were statistically significant for all variables evaluated. This is the first time that an initial process of acclimatization and morphogenetic performance with a known genotype individual of V. planifolia, is reported under greenhouse condition, in Costa Rica. Therefore, it is the first attempt to the ex situ conservation of the species as a part of an integrated program focus on the in situ conservation in a systematic and sustainable way, as well as, the first values of the vigorousness to some growth variables out of natural conditions.

Structural and Electrochemical Investigation of Na+ Insertion Into λ-Mn1-xNixO2

2015 ◽  
Vol 1810 ◽  
Author(s):  
J. R. Kim ◽  
G. G. Amatucci
Keyword(s):  
High Voltage ◽  
Low Cost ◽  
Electrochemical Techniques ◽  
Positive Electrode ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
Positive Electrodes ◽  
Insertion Mechanism ◽  
First Time

AbstractIncreased demand for low cost energy storage options has expanded the scope of Na+ batteries considerably; and with the growing interest in Na-based chemistries, the importance of high voltage positive electrodes is quickly realized as the Na/Na+ redox introduces lower operating voltages as compared to Li/Li+ based electrochemical cells. The 4.7V LiMn1.5Ni0.5O4 spinel has exhibited considerable properties as a high voltage Li+ positive electrode, with a host structure (λ-Mn0.75Ni0.25O2) that may provide an analogous high voltage Na+ positive electrode. Structural and electrochemical properties of NaxMn1.56Ni0.44O4 and NaxMn2O4 are investigated for the first time[1] utilizing ex-situ, in-situ X-ray diffraction, and high-resolution electrochemical techniques to provide an insightful study of the Na+ insertion mechanism.

scholarly journals A soft molecular 2Fe–2As precursor approach to the synthesis of nanostructured FeAs for efficient electrocatalytic water oxidation

2020 ◽  
Vol 11 (43) ◽  
pp. 11834-11842
Author(s):  
Rodrigo Beltrán-Suito ◽  
Viktoria Forstner ◽  
J. Niklas Hausmann ◽  
Stefan Mebs ◽  
Johannes Schmidt ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Water Oxidation ◽  
Ex Situ ◽  
X Ray ◽  
Active Structure ◽  
First Time ◽  
X Ray Absorption

A molecularly derived FeAs has been used as an electro(pre)catalyst for an efficient alkaline OER for the first time and subsequently, its active structure has been determined by quasi in situ X-ray absorption spectroscopy and ex situ methods.

Life as a Machine

2020 ◽  
pp. 209-233
Author(s):  
John Parrington
Keyword(s):  
Amino Acids ◽  
Hot Springs ◽  
Double Helix ◽  
Bacterial Genome ◽  
Letter Pair ◽  
Human Beings ◽  
Specific Sequence ◽  
Dna Double Helix ◽  
First Time ◽  
Yeast Genomes

Bacteria are a source of many of the tools used in biotechnology. A technique called the polymerase chain reaction, or PCR, made it possible for the first time to amplify tiny starting amounts of DNA and has revolutionised medical diagnosis, testing of IVF embryos for mutations, and forensic science. PCR involves the repeated generation of DNA from a starting sequence in a cycle, one stage of which occurs at boiling point. Because of this PCR uses a DNA polymerase enzyme purified from an ‘extremophile’ bacterium that lives in hot springs. More recently scientists have constructed artificial bacterial or yeast genomes from scratch. The next step will be to create reconfigured bacteria and yeast with enhanced characteristics for use in agriculture, energy production, or generation of new materials. Some scientists are now seeking to expand the genetic code itself. The DNA code that human beings share with all other species on the planet has four ‘letters’, A, C, G, and T, which pair as A:T and C:G to join the two strands of the DNA double helix. And each particular triplet of DNA letters, for instance CGA, or TGC, codes for a specific amino acid, the 20 different amino acids joining together in a specific sequence to make up a particular protein. Scientists have now developed a new DNA letter pair, X:Y. By introducing this into an artificial bacterial genome, it is becoming possible to create many more amino acids than the current 20 naturally occurring ones, and thereby allowing many new types of proteins.

scholarly journals Injuries reflecting intra- and interspecific interactions in the Snake-eyed Skink Ablepharus kitaibelii (Bibron & Bory de Saint-Vincent, 1833) (Squamata, Scincidae) from Bulgaria

Herpetozoa ◽  
2019 ◽  
Vol 32 ◽  
pp. 171-175
Author(s):  
Vladislav Vergilov ◽  
Yurii V. Kornilev
Keyword(s):  
Interspecific Interactions ◽  
The Body ◽  
Ex Situ ◽  
Back Side ◽  
Costs And Benefits ◽  
Predator Pressure ◽  
Behavioral Studies ◽  
The Individual ◽  
First Time

The Snake-eyed Skink’s intra- and inter-specific interactions and their impacts on the individual (e.g. injuries) have received little attention so far. As part of copulation, male lizards bite the females; observations confirm an old report that bites occur in the fore side of the body, along with more recently published information about the back side. Additionally, out of 435 individuals observed in situ, 10 had missing extremities (toes, ankles, etc.); however, further studies should identify the causes of such injury, e.g. male-male combat, predators. For the first time, an adult male was observed biting a juvenile ex situ; the specific reasons, however, remain unknown. This report should generate further interest in ecological and behavioral studies, assessing the costs and benefits to potential territorial defense, intra-specific combat, and predator pressure and escape mechanisms.

Kinetics of electrode reaction of Eu3+/Eu2+ studied by cyclic voltammetry and tast polarography

1990 ◽  
Vol 55 (7) ◽  
pp. 1666-1672 ◽  
Author(s):  
Jaroslav Němec ◽  
Tomáš Loučka
Keyword(s):  
Cyclic Voltammetry ◽  
Kinetic Parameters ◽  
Electrochemical Behaviour ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Dropping Mercury Electrode ◽  
Sulphate Media ◽  
First Time ◽  
Kinetics Of ◽  
The Eu

The electrochemical behaviour of europium at the dropping mercury electrode was studied in the medium of 1M-NaClO4, 1M-NaCl, 1M-NaNO3, and 1M-Na2SO4. The curves obtained by Tast polarography and the kinetic parameters (ks, α) for the Eu3+/Eu2+ system in the medium of perchlorate and chloride solutions are in accord with the results published earlier. The kinetic parameters in nitrate and sulphate media are given for the first time. In the medium of nitrates, the electrode reaction is probably accompanied by a chemical reaction.

In Situ and Ex Situ Studies on the Degradation of Pd/C Catalyst for Proton Exchange Membrane Fuel Cells

2014 ◽  
Vol 11 (5) ◽  
Author(s):  
Yongfu Tang ◽  
Shichun Mu ◽  
Shengxue Yu ◽  
Yufeng Zhao ◽  
Hongchao Wang ◽  
...  
Keyword(s):  
Single Cell ◽  
Electrochemical Impedance ◽  
Degradation Mechanism ◽  
Single Cells ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Ex Situ ◽  
Constant Current ◽  
Stress Tests

To investigate the degradation mechanism of the as-prepared Pd/C catalyst, in situ and ex situ accelerated stress tests were carried out via potential cycling. Durability tests of the single cells with Pd/C catalysts were performed through an interval constant current density mode. Electrochemical impedance spectroscopy (EIS) was applied to measure the impedance of the single cell during degradation tests. Results indicate that the degradation of Pd/C catalyst may be attributed to the phase transition of absorbed α-phase PdH to β-phase PdH, the dissolution of Pd metal, and the size increase of Pd nanoparticles. Moreover, the degradation of single cell may be predominantly ascribed to the degradation of catalyst, the deterioration of contact between electronic/ionic conductors, as well as the flooding of gas diffusion channels.

Anomalous Composition Dependence of Optical Energies of MBE-grown InGaN

2003 ◽  
Vol 798 ◽  
Author(s):  
I. Fernandez-Torrente ◽  
D. Amabile ◽  
R. W. Martin ◽  
K. P. O'Donnell ◽  
J.F.W. Mosselmans ◽  
...  
Keyword(s):  
Composition Dependence ◽  
Ex Situ ◽  
Optical Absorption Spectroscopy ◽  
Large Area ◽  
X Ray ◽  
Luminescence Peak ◽  
Growth Method ◽  
Pl Mapping ◽  
First Time

ABSTRACTA direct comparison of the optical energies of MBE- and MOVPE-grown InxGa1-xN epilayers of similar InN content is performed for the first time. The InN fraction in the 7 MBE samples examined ranged from x ∼ 0.11 to x ∼ 0.35 while the range in available MOVPE epilayers is [0, 0.4]. Wavelength Dispersive X-ray (WDX) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopies were used to measure composition and local structure (alloy character) of the samples. Cathodoluminescence (CL) spectroscopy in situ, ex situ photoluminescence (PL) mapping and large-area optical absorption spectroscopy were used to measure various optical energies. The composition dependence of the optical energies is determined by the growth method. The absorption bandgap and luminescence peak energies vary linearly with x for both growth methods, suggesting a near-zero value of the bowing parameter. But the energy intercept at zero InN content in MOVPE samples is close to the wurtzite-GaN bandgap of 3.4 eV at room temperature, as expected, while the equivalent for MBE samples falls near 3.2 eV.

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