Art Electrostatic Potential Pdf


Thursday, May 2, 2019

field, we can define electrostatic potential energy of a charge in an electrostatic certain electrostatic potential energy, this work done increases its potential. Electric Potential. Potential and Potential Energy. In the introductory mechanics course, we have seen that gravitational force from the. Earth on a particle of. The Electric Potential of Point. Charges. Equipotential Surfaces and the . Electric Field. Capacitors and Dielectrics. Electrical Energy Storage.

Electrostatic Potential Pdf

Language:English, Spanish, French
Published (Last):02.06.2016
ePub File Size:23.37 MB
PDF File Size:17.42 MB
Distribution:Free* [*Regsitration Required]
Uploaded by: GERALYN

Objectives: After completing this module, you should be able to: • Understand an apply the concepts of electric potential energy, electric potential, and electric. Electric potential. Exercise: a potential difference of V is applied across a pair of parallel plates m apart. (b) an electron is placed between the plates. Electric Potential. • We define an Electric Potential, V, as the energy per unit charge, q: • V = U/q. • Describes what would happen to a charge if it was placed in.

Both molecules contain the type of nitro- competition to produce H-bonded compounds, lead- gens and oxygens responsible for the presence of ing to lower association constants among NABs that potential wells, then we can visualize such atoms as show on enthalpy changes.

Nevertheless, problems acceptor-like elements. On the other hand, hydrogens arise when one tries to elucidate the kind of micro- are recognized as donor-type entities with opposite scopic conformation adopted by dimers.

A direct sign. Hence, formation of different hydrogen bridges way to obtain structural information is by forming between G and C becomes possible due to the crystalline complexes among the different deriva- presence of donor and acceptor species in both frag- tives of the NABs, and performing the corresponding ments. As a result, different dimer residues are ex- X-ray diffraction analysis.

The different conformers are de- Observations under this scheme show that nucleic scribed according to the donor and acceptor atoms acid bases are capable of linking with themselves taking part in the binding. In all these structures at producing homologous pairs, or with other bases least two hydrogen links appear 2 , and in most cases resulting in mixed complexes where two, three or donor atoms from one fragment fall deep inside the more NAB derivatives coexist in the H-bonded infi- potential wells created by the acceptor atoms of the nite network.

Water molecules, and either tautomeric partner molecule. Inter- these H-bonded pairs in vacuo has so far been estingly enough is the fact that contrary to NABs missing. However, in solution, pair formation of immersed in solution, in crystals, Watson—Crick nucleic acid bases can be indirectly inferred.

Nucleic linkages among the different nucleic acid derivatives seem to be energetically less stable than other types 2 of H-bonding. Differences in their stability are at- In general, pairs with only one hydrogen bridge are energeti- cally less stable than those which contain two or more bridges.

Thus, in this work, a H-bonded complex should be understood as For the particular case of Watson—Crick pair containing two or more H-links. For the GC Watson—Crick pair, the corresponding sets or confined within a shorter region. Such potential are O10, H14 of guanine and N3, H9 of cytosine. The extra wells in turn become the characteristic reactive cen- hydrogen bridge in the GC pair is implicitly contemplated in this binding since two links are enough to determine the kind of pair ters of the Watson—Crick pair complexes.

The lowest values of the electrostatic potential c Take note that, in addition to mixed dimers, homologous pairs surfaces corresponding to the AT and GC com- should be also contemplated from the table. In comparison with single nucleic acids, the relative order among min- ima is greatly modified by pair formation.

For exam- Mulliken analysis. Similar charge population results ple, the most drastic change is recorded for site O8 to these reported for single residues are found, refer of cytosine. In the case of pairs, active site O8 shows to Fig. No Mulliken charge transfer is noted from the shallowest minimum, contrary to the case of one molecule to the other since each fragment that single nucleic acids where it represents the deepest builds the complex essentially retains its zero initial one.

Electric potential

However, substantial electronic reorganiza- For other pair conformations among NABs, with tion occurs within each nucleic acid at the interaction equal demand of time-consuming computations, sim- region.

If we compare Mulliken charges of those ilar results are expected. In fact, Watson—Crick atoms taking part in the binding, before and after the dimers represent just an example where chemical formation of the complex, it is observed that hydro- active centers of single nucleic acids are potentially gens increase their positive charge while nitrogens capable of linking a molecular partner in different and oxygens increase their negative charge. The new conformations.

Still, the question remains about pos- electron distribution induces local charge polariza- sible changes of MEPs and population charges of tion between the partner molecules forming the NABs when other DNA constituents remain in their dimer.

It calls our attention that carbons 2, 5 and 6 of vicinity, a topic to be investigated next.

NCERT Solutions for Class 12 Physics Chapter 2

The case of the B-DNA single strand away from the binding region. MEPs for the Watson—Crick nucleic complexes In this section we analyze charge populations and are likewise depicted in Fig. For instance, a units. Mulliken charge populations and molecular electrostatic potentials of DNA pair complexes. For comparison, charge populations of nucleic acids before pairing are also included. This analysis corresponding atoms, taking part in sugars and phos- represents a more general study than previous studies phates of the above mini-strands, indicate small dif- performed on single nucleic acids by other authors as ferences.

In Fig. Only three curves are tions of phosphate groups and sugar compounds. It is not difficult to see that the largest long range nature of the forces that participate in the discrepancies in sugar compounds are recorded for electrostatic potential expression. The deviations are indeed small and, in most complexes, this is doublets of nucleotides. Sixteen instances, curves follow a similar trend. Changes possible structures is the total number of compounds; computed on atoms C3, C4 and H9 of sugar however, we only need analyze the four combina- molecules are attributed to a poor influence of the tions between purines and pyrimidines to determine adjacent nucleic bases that participate in the doublet, electron distribution changes.

The illustrate the AT and AG doublets and establish atom phosphate may stay in between or at the end of the numbering. In spite of that, atomic Careful comparisons of Mulliken populations among population discrepancies in sugar compounds and Fig.

Dark and transparent surfaces belong to A and T, respectively. Small rings identify relative minima and strips gaps of 10 kcalrmol, starting from downwards, in the electrostatic potential surfaces. Refer to Fig. Dark and transparent surfaces belong to A and G, respectively.


Small rings identify relative minima and strips gaps of 10 kcalrmol, starting from au downwards, in the electrostatic potential surfaces. Refer to Figs.

Such an argument Mulliken population comparisons have been also is based on the fact that DNA assumes a dynamical carried out for nucleic acid bases in the four possible role in a variety of biochemical processes. Therefore, single strands. We find that charge populations of A the flexibility of DNA is one of the main reasons in the sequence AG are almost identical to these of that such a molecule is capable of preserving, even A in AT, see Fig.

However, take note that it may be equally in CG and CT. Then, within the doublet approxima- valid the conclusion that the observed differences in tion, Mulliken charges of nucleic bases are indiffer- population charges of sugar and phosphates are im- ent to the contiguous base, whether this last one is portant enough that such subunits can be considered situated above or under the reference nucleic acid.

Neverthe- in nucleic bases are produced by the near presence of less, we remark and insist on the molecular flexibil- sugar and phosphate compounds. For instance, ade- ity of DNA to preserve the genetic information under nine alone and within the mini-strands shows sub- relatively wide structural and electronic limits.

Con- stantially different charge populations, refer to Fig. Equivalent results occur for the other bases. The molecular groups preserve their electronic identity new charge distribution of nucleic bases in the mini- within some margins and constitute not only a struc- strands is mainly perceived at their junction with the R. In become slightly more inaccessible within the DNA these figures, the two surfaces generated by the A complex. Still note that the external part of the nucleotide show similar not only in shape, but also in electrostatic potential surfaces produced by phos- reference to the depth of potential wells.

Navigation menu

However, phate groups of purines and pyrimidines resemble this is not the case when we compare the adenine each other. In fact, main differences in MEPs of surface with that generated by the G nucleotide. In contrast, In Table 1, we consider the lowest values in the adenine and its corresponding phosphate molecule MEP surface associated to nucleic acid bases.

Values appear with purines against these of pyrimidines, clear differ- deviations in order to summarize results in one cen- ences emerge. Pyrimidines present surfaces separated tral value and be able to establish relative order from those of the phosphate group due to the inter- among minima. In particular, we observe that chemi- R. Mulliken populations of adenine alone and in the mini-strands AG and AT.

They are closely fol- cleotide, in this case G or T. For the interesting lowed by these produced by O8 and N3 of cytosine, mini-sequence AC, which involves both A and C, we and O7 of thymine. Note also that the relative order observe a minimum out of the plane of A but do not among minima in this last column differs from previ- observe a minimum out of the plane of C. A similar ous columns of Table 1.

Hence, predicted for single nucleic acids and base pairs. Other au- Based on the above results of Mulliken charge thors w3x have found secondary minima out of the populations and MEP for phosphates, sugars and planes of nucleic acids A and C.

Nevertheless, a nucleic acid bases, we conclude that recognition of careful DFT analysis indicates that it is due to the specific DNA sequences proceeds at short distances. When nucleic The assertion derives from the fact that Mulliken bases take part in base pairs, such hydrogens become charges and MEPs associated to phosphate and sugar planar and the secondary minima disappear.

In dinu- subunits keep to great part their own electronic cleotides, minima out of the molecular plane are identity as a result of a relative poor influence from observed for A in AG and AT, and for C in CG and adjacent nucleic acid bases.

Therefore, a partner CT. Then, it is selective process favoring a close contact recogni- assumed that selective interactions between partner tion. This result is experimentally evidenced in gene molecules with DNA may be characterized as close regulatory proteins w24x.

Also, they should one or another adjacent nucleic acid base. In this last case we different preferred sites for an electrophilic attack to call attention to the molecular machine approxima- these found in single nucleic acids and pair com- tion, where one might refer to a molecular machine plexes.

This is due to the additional contributions of as an assembly of polymeric molecules with one of phosphate and sugar compounds, which are not neg- them sliding over the other, in order to transport ligible because of the long range nature of the elec- some energy or certain type of mass. Note that the trostatic forces that appear in the MEP expression.

Finally, it is important to mention that, the set of hydrogen atoms that participate in the binding of 4. Conclusions nucleic acid bases not only ensures a weak linking between bases, but also help to preserve the identity In this work we have shown the simplicity and of each base inside the DNA complex.

This is due to importance of molecular electrostatic potentials and the limited charge reorganization that hydrogen atoms Mulliken charge populations to elucidate reactive can suffer in comparison with heavier elements that, centers of DNA. The application of both schemes to otherwise, could appear at the interaction region.

Exper- cess of exact duplication, while electronic identity iments based on their derivatives confirm the domi- preservation of nucleic acids in DNA makes possible nant role of the electrostatic force, that participates in the saving and interpretation of the genetic informa- the MEPs, for predicting the pairing of compounds tion.

Particular attention given to Watson—Crick dimers showed that, electronic charge is mainly reaccommodated at the interaction region References between fragments, inducing local polarization, with w1x P.

Politzer, D. Murray, K. Bonaccorsi, A. Pullman, E. Scrocco, J. Tomasi, Theor. A study on nucleotides indicated that sugar Chim.

Wiener, M. Grice, J. Murray, P. Politzer, J. The typical configuration of a ZnO nanogenerator.

When pushed by an AFM tip, mechanical deflection gives rise to an electrical field, the power of which can be released.

The pushing force increases from 1 to 3 , until 4 the wire is released. The continuum model proposed by Michalski et al. In this paper we propose a continuum model for the electrostatic potential in a laterally bent NW. The theory directly establishes the physical basis of nanopiezotronics and nanogenerator as proposed previously.

Analytical Solution via Perturbation Theory. System Setup and Governing Equations. The typical setup of a vertical piezoelectric nanowire nanogenerator is shown in Figure 1. Our theoretical objective is to derive the relationship between the potential distribution in the NW and the dimensionality of the NW and magnitude of the applied force at the tip. For this purpose, we start from the governing equations for a static piezoelectric material, which are three sets: mechanical equilibrium equation eq 1 , constitutive equation eq 2 , geometrical compatibility equation eq 3 , and Gauss equation of electric field eq 4.Exper- cess of exact duplication, while electronic identity iments based on their derivatives confirm the domi- preservation of nucleic acids in DNA makes possible nant role of the electrostatic force, that participates in the saving and interpretation of the genetic informa- the MEPs, for predicting the pairing of compounds tion.

Mohan, A. Calculated electrostatic potential distributions have been used in Brownian dynamics simulations to obtain near quantitative agreement with, for example, measured kinetics.

Cobianu, O. Mulliken charge populations and molecular electrostatic potentials of DNA nucleic acid bases. When pushed by an AFM tip, mechanical deflection gives rise to an electrical field, the power of which can be released.

Rich, Prog.

Encouraged by the simplicity and general good performance of the electrostatic potential scheme, 2. Their minima are reported in Table 1. Labanowski, J.