scholarly journals GIS-NaP1 zeolite microspheres as potential water adsorption material: Influence of initial silica concentration on adsorptive and physical/topological properties

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Pankaj Sharma ◽  
Ju-Sub Song ◽  
Moon Hee Han ◽  
Churl-Hee Cho
Keyword(s):  
Water Adsorption ◽  
Topological Properties ◽  
Initial Silica ◽  
Silica Concentration

Electron Microscopy of Nucleic Acids

1974 ◽  
Vol 32 ◽  
pp. 302-303
Author(s):  
Norman Davidson
Keyword(s):  
Electron Microscopy ◽  
Nucleic Acids ◽  
Basic Protein ◽  
Molecular Biologist ◽  
Topological Properties ◽  
Protein Film ◽  
Polynucleotide Chain

The basic protein film technique for mounting nucleic acids for electron microscopy has proven to be a general and powerful tool for the working molecular biologist in characterizing different nucleic acids. It i s possible to measure molecular lengths of duplex and single-stranded DNAs and RNAs. In particular, it is thus possible to as certain whether or not the nucleic acids extracted from a particular source are or are not homogeneous in length. The topological properties of the polynucleotide chain (linear or circular, relaxed or supercoiled circles, interlocked circles, etc. ) can also be as certained.

Structure, Stability and Water Adsorption on Ultra-Thin TiO2 Supported on TiN

2019 ◽  
Author(s):  
Jose Julio Gutierrez Moreno ◽  
Marco Fronzi ◽  
Pierre Lovera ◽  
alan O'Riordan ◽  
Mike J Ford ◽  
...  
Keyword(s):  
Density Functional ◽  
Water Adsorption ◽  
Chemical Potential ◽  
Energy Gap ◽  
Molecular Water ◽  
Structure Stability ◽  
Ambient Conditions ◽  
Rutile Structure ◽  
The Stability ◽  
The One

<p></p><p>Interfacial metal-oxide systems with ultrathin oxide layers are of high interest for their use in catalysis. In this study, we present a density functional theory (DFT) investigation of the structure of ultrathin rutile layers (one and two TiO<sub>2</sub> layers) supported on TiN and the stability of water on these interfacial structures. The rutile layers are stabilized on the TiN surface through the formation of interfacial Ti–O bonds. Charge transfer from the TiN substrate leads to the formation of reduced Ti<sup>3+</sup> cations in TiO<sub>2.</sub> The structure of the one-layer oxide slab is strongly distorted at the interface, while the thicker TiO<sub>2</sub> layer preserves the rutile structure. The energy cost for the formation of a single O vacancy in the one-layer oxide slab is only 0.5 eV with respect to the ideal interface. For the two-layer oxide slab, the introduction of several vacancies in an already non-stoichiometric system becomes progressively more favourable, which indicates the stability of the highly non-stoichiometric interfaces. Isolated water molecules dissociate when adsorbed at the TiO<sub>2</sub> layers. At higher coverages the preference is for molecular water adsorption. Our ab initio thermodynamics calculations show the fully water covered stoichiometric models as the most stable structure at typical ambient conditions. Interfacial models with multiple vacancies are most stable at low (reducing) oxygen chemical potential values. A water monolayer adsorbs dissociatively on the highly distorted 2-layer TiO<sub>1.75</sub>-TiN interface, where the Ti<sup>3+</sup> states lying above the top of the valence band contribute to a significant reduction of the energy gap compared to the stoichiometric TiO<sub>2</sub>-TiN model. Our results provide a guide for the design of novel interfacial systems containing ultrathin TiO<sub>2</sub> with potential application as photocatalytic water splitting devices.</p><p></p>

The Effect of Topological Properties on Duration Perception of Oddball Stimuli

2013 ◽  
Vol 45 (12) ◽  
pp. 1324-1333
Author(s):  
Baolin LI ◽  
Youguo CHEN ◽  
Xiangyong YUAN ◽  
Jackson Todd ◽  
Xiting HUANG
Keyword(s):  
Topological Properties

Molecular Topological Properties of Alkylating Agents Based Anticancer Drug Candidates Via Some Ve-degree Topological Indices

2020 ◽  
Vol 16 (2) ◽  
pp. 190-195 ◽  
Author(s):  
Süleyman Ediz ◽  
Murat Cancan
Keyword(s):  
Anticancer Drugs ◽  
Anticancer Drug ◽  
Alkylating Agents ◽  
Topological Indices ◽  
Pharmacological Properties ◽  
Topological Properties ◽  
Drug Candidates ◽  
New Drug ◽  
Atom Bond ◽  
Dual Target

Background: Reckoning molecular topological indices of drug structures gives the data about the underlying topology of these drug structures. Novel anticancer drugs have been leading by researchers to produce ideal drugs. Materials and Methods: Pharmacological properties of these new drug agents explored by utilizing simulation strategies. Topological indices additionally have been utilized to research pharmacological properties of some drug structures. Novel alkylating agents based anticancer drug candidates and ve-degree molecular topological indices have been introduced recently. Results and Conclusion: In this study we calculate ve-degree atom-bond connectivity, harmonic, geometric-arithmetic and sum-connectivity molecular topological indices for the newly defined alkylating agents based dual-target anticancer drug candidates.

SOME TOPOLOGICAL PROPERTIES OF HAMEL BASES

1994 ◽  
Vol 20 (2) ◽  
pp. 819
Author(s):  
Muthuvel
Keyword(s):  
Topological Properties

scholarly journals DNA thermodynamics shape chromosome organization and topology

2013 ◽  
Vol 41 (2) ◽  
pp. 548-553 ◽  
Author(s):  
Andrew A. Travers ◽  
Georgi Muskhelishvili
Keyword(s):  
Dna Sequence ◽  
Dna Sequences ◽  
Chromosome Organization ◽  
Topological Properties ◽  
Genetic Organization ◽  
And Topology ◽  
Dna Translocases

How much information is encoded in the DNA sequence of an organism? We argue that the informational, mechanical and topological properties of DNA are interdependent and act together to specify the primary characteristics of genetic organization and chromatin structures. Superhelicity generated in vivo, in part by the action of DNA translocases, can be transmitted to topologically sensitive regions encoded by less stable DNA sequences.

Measurement, analysis and prediction of amoxicillin oral dose stability from integrated molecular description approach and accelerated predictive stability (APS)

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Camille Merienne ◽  
Chloe Marchand ◽  
Samira Filali ◽  
Damien Salmon ◽  
Christine Pivot ◽  
...  
Keyword(s):  
Oral Dose ◽  
Shelf Life ◽  
Chromatographic Analysis ◽  
Water Adsorption ◽  
Degradation Mechanism ◽  
Oral Dosage ◽  
Hydroxyl Groups ◽  
Humid Atmosphere ◽  
Intramolecular Hydrogen ◽  
The Impact

AbstractBackgroundStability of low amoxicillin oral dosage form (5 mg) used in reintroduction drug test was not fully documented. Furthermore, the impact of (1) salt moiety of amoxicillin and (2) amoxicillin – excipient interactions upon the antibiotic formulation stability during the storage was not characterized so that the estimation of the pharmaceutical expiration date from shelf-life was uncertain. Thus, the main goal of this study was to estimate the shelf-life of two formulations of amoxicillin, using a semi-predictive methodology.MethodsAmoxicillin sodium (AS) and amoxicillin trihydrate (ATH), corresponding to 5-mg amoxicillin, were compounded with microcrystalline cellulose (MCC) in oral hard capsules which were, then, submitted to four environmental conditions (25 °C / 60% or 80% relative humidity (RH); 40 °C / 75% RH; 60 °C / 5% RH) in climatic chambers for 45 and 84 days. Therefore, the characterization of amoxicillin-MCC mixture was assessed by attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) The profiles of amoxicillin content (determined by stability indicating chromatographic method) as a function of storage time, temperature and RH were fitted to pre-defined kinetic models performed by accelerated predictive stability (APS).ResultsATR-FTIR analysis of AS, ATH, MCC and bulk specimens stored in heated and humid atmosphere confirmed water sorption to cellulose described by a broad and unresolved 3600 to 3000 cm−1 band associated with (1) general intramolecular and intermolecular hydrogen bonding between water and hydroxyl groups of the cellulose, and with (2) free hydroxyl in cellulose. Moreover, a dramatic decrease of absorption at 1776 and 1687 cm−1 respectively characteristic of the β-lactam ring (νC=O) and amide group (νC=O), was revealed as a consequence of AS and ATH degradation caused by moisturization of bulk. Amoxicillin degradation was established by chromatographic analysis showing faster AS degradation than ATH throughout time exposure. The combined effects of temperature – RH were successfully modeled by APS, where AS and ATH showed accelerated (auto-catalysis degradation mechanism) and linear degradation, respectively. The faster AS degradation was assumed to be linked to lower hydrogen donor to hydrogen acceptor count ratio and polar surface than ATH, increasing the probability of AS hydrolysis by water adsorption to AS-MCC solid dispersion (e.g., by reduction of protective intramolecular hydrogen bonds between AS molecules). Furthermore, the compounding which involved a drastic homogenization of solids may have affected the crystalline degree of MCC with an increase of amorphous phase more sensitive to water adsorption.ConclusionsThe improvement of amoxicillin compounding for oral dose forms might be rationalized by taking into account the molecular descriptors of salt moiety and excipients, improved by the choice of an appropriate process of production, characterized from infrared vibrational spectroscopy and chromatographic analysis and finally predicted from accelerated stability assays.

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