scholarly journals Statistical mechanics of a double-stranded rod model for DNA melting and elasticity

Soft Matter ◽  
2020 ◽  
Vol 16 (33) ◽  
pp. 7715-7726
Author(s):  
Jaspreet Singh ◽  
Prashant K. Purohit
Keyword(s):  
Statistical Mechanics ◽  
Room Temperature ◽  
Bath Temperature ◽  
Dna Melting ◽  
Strand Separation ◽  
Rod Model ◽  
Tensile Forces ◽  
External Loads

The double-helical topology of DNA observed at room temperature in the absence of any external loads can be disrupted by increasing the bath temperature or by applying tensile forces, leading to spontaneous strand separation known as DNA melting.

scholarly journals Statistical mechanics of base stacking and pairing in DNA melting

2004 ◽  
Vol 70 (5) ◽  
Author(s):  
Vassili Ivanov ◽  
Yan Zeng ◽  
Giovanni Zocchi
Keyword(s):  
Statistical Mechanics ◽  
Dna Melting ◽  
Base Stacking

scholarly journals The Influence of Mn2+on DNA structure in the presence of Na+ions: A Raman spectroscopic study

2006 ◽  
Vol 20 (5-6) ◽  
pp. 261-268 ◽  
Author(s):  
Cristina M. Muntean ◽  
Rolf Misselwitz ◽  
Heinz Welfle
Keyword(s):  
Conformational Changes ◽  
Room Temperature ◽  
Dna Structure ◽  
Dna Melting ◽  
Physiological Concentration ◽  
Raman Spectroscopic ◽  
Calf Thymus ◽  
Dna Backbone ◽  
Na Ions ◽  
Phosphate Groups

The influence of Mn2+ions on the structure of natural calf thymus DNA was studied by Raman spectroscopy. Measurements were done at room temperature and pH 6.2±0.2, in the presence of the physiological concentration of 150 mM Na+ions, and in the presence of Mn2+concentrations that varied between 0 and 600 mM. No condensation of DNA was observed at any of the Mn2+concentrations. At 5 mM Mn2+and 150 mM Na+no significant influence of Mn2+ions on the DNA structure can be observed. Compared with our previous results obtained at 10 mM Na+ions, binding of Mn2+ions to charged phosphate groups and to DNA bases is inhibited in the presence of 150 mM Na+ions. DNA backbone conformational changes were not observed in the whole concentration range of Mn2+ions as judging from the Raman spectra. No evidence for DNA melting was identified. A high Mn2+affinity for binding to guanine N7 and possibly, in a much lesser extent, to adenine have been found.

CURVED-IN-PLANE CABLE-STAYED BRIDGES: A MATHEMATICAL MODEL

2012 ◽  
Vol 12 (03) ◽  
pp. 1250011 ◽  
Author(s):  
IOANNIS G. RAFTOYIANNIS ◽  
GEORGE T. MICHALTSOS
Keyword(s):  
Mathematical Model ◽  
Three Dimensional ◽  
3D Analysis ◽  
Continuum Approach ◽  
Theoretical Formulation ◽  
Long Span ◽  
Dynamic Analyses ◽  
Tensile Forces ◽  
External Loads ◽  
Cable Stayed Bridges

A mathematical model suitable for static and dynamic analyses of curved-in-plane cable-stayed bridges is proposed. By expressing the tensile forces of the cables in relation to the deck and pylon deformations, the problem is reduced to the solution of a beam curved-in-plane that is subjected to the usual permanent and external loads and to the tensile forces of the cables, the latter being functions of the deformation of the beam. The theoretical formulation presented is based on a continuum approach, which is suitable for the three-dimensional (3D) analysis of long span cable-supported bridges. Numerical examples will be analyzed to illustrate the applicability of the proposed approach.

Statistical mechanics of DNA melting in confined geometry

2019 ◽  
Vol 2019 (4) ◽  
pp. 043501 ◽  
Author(s):  
Dibyajyoti Mohanta ◽  
Debaprasad Giri ◽  
Sanjay Kumar
Keyword(s):  
Statistical Mechanics ◽  
Dna Melting ◽  
Confined Geometry

Study on Performances of Cyanethyl Chitosan Fiber Prepared from [Asp]Cl Ionic Liquid

2012 ◽  
Vol 581-582 ◽  
pp. 698-701
Author(s):  
De Zeng Xu ◽  
Ting Zhao ◽  
Zhi Chao Liu ◽  
Lu Nan Bai ◽  
Jing Guo
Keyword(s):  
Ionic Liquid ◽  
Aspartic Acid ◽  
Room Temperature ◽  
Breaking Strength ◽  
Fiber Strength ◽  
Bath Temperature ◽  
Wet Spinning ◽  
Ft Ir ◽  
Acid Hydrochloride ◽  
Chitosan Fiber

Aspartic acid hydrochloride ionic liquid ([Asp]Cl) was successfully synthesized from aspartic acid powder and 36% hydrochloric acid. The derivative of chitosan cyanoethyl chitosan was prepared by acrylonitrile and alkali chitosan at room temperature. Structures of ionic liquid and cyanoethyl chitosan were characterized by FT-IR. Crystalline properties of cyanoethyl chitosan were characterized by XRD. Cyanoethyl chitosan was dissolved in [Asp]Cl ionic liquid aqueous solution and subjected to wet spinning. The mechanical properties of cyanoethyl chitosan fibers were tested by type LLY-06 electronic single fiber strength tester, and the surface morphology of fibers were observed by microscope. The results show that the maximum breaking strength of fiber was 2.212CN/dtex when the concentration of cyanoethyl chitosan was 6.5% relativing to 3% ionic liquid and the coagulating bath temperature was 30°C.

scholarly journals Zn2+–DNA interactions in aqueous systems: A Raman spectroscopic study

2009 ◽  
Vol 23 (3-4) ◽  
pp. 155-163 ◽  
Author(s):  
Cristina M. Muntean ◽  
Konstantinos Nalpantidis ◽  
Ingo Feldmann ◽  
Volker Deckert
Keyword(s):  
Room Temperature ◽  
Helical Structure ◽  
Intensity Change ◽  
Dna Melting ◽  
Dna Interactions ◽  
Raman Spectroscopic ◽  
Double Helical Structure ◽  
Calf Thymus ◽  
Concentration Changes ◽  
Phosphate Groups

The influence of Zn2+ions on the structure of natural calf thymus DNA was studied by Raman spectroscopy. Measurements were done at room temperature and pH 6.2±0.1, in the presence of 10 mM Na+, and of Zn2+in a concentration range varying between 0 and 250 mM, respectively. No condensation of DNA was observed.As judging from the marker bands near 681 cm−1(dG), 729 cm−1(dA), 752 cm−1(dT), and 787 cm−1(dC, dT) altered nucleoside conformations in these residues are supposed to occur, in different intervals of Zn2+ions concentration. Changes in the conformational marker centered around 835 cm−1, upon Zn2+binding to DNA, were detected. Binding of zinc(II) ions to the charged phosphate groups of DNA, stabilizing the double helical structure, is indicated in the spectra. We have found that binding of metal ions at N3 of cytosine takes place at zinc(II) concentrations between 150–250 mM and interaction of Zn2+ions with adenine is observed in a concentration range from 10 to 250 mM. Binding of zinc(II) ions to N7 of guanine and, possibly, in a lesser extent to adenine was also observed as indicated by the Raman marker bands near 1490 and 1581 cm−1. There is no intensity change of the band at 1668 cm−1, suggesting no change in their base pairing and no change induced in the structure of water by Zn2+cations. No evidence for DNA melting was identified.

Time-Dependent Ductility of Electro-Deposited Copper

1992 ◽  
Vol 114 (4) ◽  
pp. 448-454 ◽  
Author(s):  
Yoshiki Oshida ◽  
P. C. Chen ◽  
J. D. Reid ◽  
T. Nishihara
Keyword(s):  
Room Temperature ◽  
Printed Circuit Boards ◽  
Bath Temperature ◽  
Electrode Position ◽  
Electron Microscopic ◽  
Ductility Property ◽  
Copper Deposits ◽  
Bulge Testing ◽  
Stress Changes ◽  
Flexible Printed Circuit

Mechanical ductility property of copper deposits is one of the most important factors necessary to provide a reliable component for the flexible printed circuit boards. Copper deposits are usually fabricated by either an electroless technique or an electrode position process. Among many parameters controlling the deposits quality, it is believed that the current density, bath temperature, the film thickness, annealing temperature and time, and the presence of impurities exhibit particularly strong influences on the mechanical ductility property. In our preliminary studies, it was found that the ductility obtained by the mechanical bulge testing showed a three-stage characteristics in terms of a room temperature annealing; namely (i) initial low ductility regime (from the right-after-copper-deposition until 12 hours aged at room temperature), (ii) transitional rapid increasing ductility regime (from 12 hours to 24 hours), and (iii) the high ductility regime (after 24 hours). In this study, X-ray diffraction analyses of the diffracted line width, the microstrain from which the dislocation density was estimated, residual macrostress, and the scanning electron microscopic observations were conducted and results were correlated with the characteristic three-stage ductility change behavior described above. Results of this study indicate that grain size and residual stress changes are strongly associated with improvement in copper ductility during the room temperature annealing.

Electrochemical Performance of Nanocrystalline Zinc Ferrite Films Synthesized Using Electrodeposition

2020 ◽  
Vol 835 ◽  
pp. 1-6
Author(s):  
E. Mostafa Elsayed ◽  
Mohamed M. Rashad ◽  
H.F.Y. Khalil ◽  
M.R. Hussein ◽  
M.M.B. El-Sabbah ◽  
...  
Keyword(s):  
Zinc Ferrite ◽  
Room Temperature ◽  
Crystal Size ◽  
Bath Temperature ◽  
Alloy Film ◽  
X Ray Diffraction ◽  
X Ray ◽  
Anodization Process ◽  
Sem Micrograph ◽  
Deposited Film

Nanocrystalline spinel zinc ferrite ZnFe2O4 thin film has been studied and synthesized via the electrodeposition-anodization process. Electrodeposited ZnFe2 alloys were obtained from aqueous sulphate bath. The resulted alloys were electrochemically oxidized in strong alkaline solution (1 M KOH) at room temperature to the analogous hydroxides. The electroanodized ZnFe2 alloy film was annealed in air at 400 °C for 2 h to get the required zinc ferrite. The electrochemical factors controlling of the electrodeposition of ZnFe2 alloys such as the bath temperature, agitation, the current density were studied and optimized. The crystal structure, crystal size and microstructure of the produced ferrites were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The deposited film was mainly composed of ZnFe2O4 based on XRD studies. The produced film had a spinel structure and the crystallite size was 4.9 nm. SEM micrograph of the resulted zinc ferrite particles shows compact crystallites shapes and agglomerated chains with smallest semicircular particles like morphology.

scholarly journals The development of the superelement approach applied to models of rod elements

2018 ◽  
Vol 251 ◽  
pp. 04045 ◽  
Author(s):  
Oleg Kovalchuk
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Analytical Solutions ◽  
Strain State ◽  
The Finite Element Method ◽  
Rod Model ◽  
Nodal Displacements ◽  
Rod Structures ◽  
External Loads ◽  
Operating Method

The article deals with the rod model for the analysis of stress-strain state of rod structures. Analytical solutions are obtained by the operating method. It is assumed that the rod elements can have variables along their axis of physicals characteristics. External loads can also vary along the axes. Calculation formulas are suitable for loads distributed according to an arbitrary law. Unlike the finite element method, defining matrices are formed after obtaining an expression, allowing to calculate the nodal forces through nodal displacements. Examples are given to demonstrate the accuracy of the obtained expressions.

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