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دسترسی آزاد مقاله
1 - Theoretical study of ISB conduction optical absorption and impurity binding energy associated with lowest excited states in QW with a new modulated potential
Redouane En-nadir Haddou El-ghaziThis paper provides a theoretical investigation of the ground and first excited-states donor impurity binding energy and the linear and nonlinear optical absorption coefficients in quantum well with novel modulated potential called Redouane-Haddou potential (RHP). Withi چکیده کاملThis paper provides a theoretical investigation of the ground and first excited-states donor impurity binding energy and the linear and nonlinear optical absorption coefficients in quantum well with novel modulated potential called Redouane-Haddou potential (RHP). Within the effective-mass theory, the Schrödinger equation has been calculated numerically using the finite element method. The analytical expressions of the optical absorption coefficients are obtained within compact density matrix theory. Our results reveal that the A-parameter has a significant influence on the confinement profile and electron states, therefore, the binding energy as well as the optical properties of the investigated system. It increases the binding energy and redshift (blueshift) associated with drop (improvement) of the linear and nonlinear optical absorption coefficients related to 2p→1s,2p→2s, and 3s→2p transitions. Moreover, it is noticed that with an appropriate choice of the A-parameter and structure dimension, the optical response of the investigated system can be tailored in a controllable manner. پرونده مقاله -
دسترسی آزاد مقاله
2 - New approach to nuclear binding energy in integrated nuclear model
Nader Ghahramany Shirvan Gharaati Mohammad GhanaatianAbstractIn this paper, the integrated nuclear model is introduced, and a binding energy formula based on this model is presented. The binding energies of all nuclides in this model are compared with available experimental values and also with values from liquid drop mod چکیده کاملAbstractIn this paper, the integrated nuclear model is introduced, and a binding energy formula based on this model is presented. The binding energies of all nuclides in this model are compared with available experimental values and also with values from liquid drop model. پرونده مقاله -
دسترسی آزاد مقاله
3 - Heat capacity and entropy of Gaussian spherical quantum dot in the presence of donor impurity
Nehal S. Yahyah Mohammad K. Elsaid Ayham ShaerAbstractThe energy states of shallow donor impurity in GaAs/AlGaAs quantum dot heterostructure with Gaussian potential have been calculated by the shifted 1/N expansion method. The effects of the impurity on the ground state energy and average statistical energy have be چکیده کاملAbstractThe energy states of shallow donor impurity in GaAs/AlGaAs quantum dot heterostructure with Gaussian potential have been calculated by the shifted 1/N expansion method. The effects of the impurity on the ground state energy and average statistical energy have been investigated. The present calculations show that the donor impurity modifies significantly the electron energy levels of spherical quantum dot and thermal properties. In addition, we have also displayed the variations of the heat capacity and entropy of donor impurity in quantum dot with the radius, confining potential depth, dimension and temperature. The comparison shows that our results are in very good agreement with the theoretical reported work. پرونده مقاله -
دسترسی آزاد مقاله
4 - The effects of isomerism and side chain mutation on binding energy and NMR/NQR tensors of L-methionylasparagine and L-asparagylmethionine
Arezoo TahanDensity functional theory methods(DFT) and natural bond orbital (NBO) analysis were used to investigate the effects of isomerism and side chain mutation at a microscopic level on the stability, binding energy and NMR/NQR tensors of structural isomers, L- methionylaspara چکیده کاملDensity functional theory methods(DFT) and natural bond orbital (NBO) analysis were used to investigate the effects of isomerism and side chain mutation at a microscopic level on the stability, binding energy and NMR/NQR tensors of structural isomers, L- methionylasparagine (Met-Asn) and L- asparagylmethionine (Asn-Met) in the gas phase. The results represented that the isomerism and side chain mutation were caused to change the relative stability, binding energy and the thermodynamics parameters of peptide bond in the considered compounds. Therefore, Asn-Met had higher binding energy and relative stability than Met-Asn. On the other hand, NMR and NQR calculations at B3LYP/6-311+G (d, p) level of theory on the optimized structures of Met-Asn and Asn-Met indicated that the isotropic chemical shielding(σiso) values of oxygen and nitrogen nuclei in two structures with similar positions were different considerably and nitrogen nuclei were more shielded than oxygen nuclei in both dipeptides. In addition, amino nitrogens (N10 nuclei) had the highest values of chemical shielding (σiso) and the nuclear quadrupole coupling constant (χ) among nitrogen nuclei and the order of chemical shielding values of nitrogen nuclei in two structural isomers was amino nitrogen> amidic nitrogen> peptide nitrogen (N10>N9>N1). The mentioned order for chemical shielding values was exactly the opposite of the order of resonance energies values of nitrogen lone pair electrons in two dipeptides. In other words, by increasing contribution of nitrogen lone pair electrons in intra-molecular resonance interactions, NMR chemical shielding around nitrogen nuclei were decreased. پرونده مقاله -
دسترسی آزاد مقاله
5 - The Study of Optical Properties Exciton Based of Molecular Quantum Dot
Ali MahmoudlooOptical properties of semiconductors, dielectrics and metals play a key role in the development of thin film solar cells. While these devices belong to photon photodetectors both the photon and wave nature of light affects their performance. Some of these problems are d چکیده کاملOptical properties of semiconductors, dielectrics and metals play a key role in the development of thin film solar cells. While these devices belong to photon photodetectors both the photon and wave nature of light affects their performance. Some of these problems are discussed. In this Paper we Solve the Schrodinger equation using the numerical method of finite difference approximation and assume that the structure of our quantum dot molecule is two cubic GaAs quantum dots in the AlxGa1-xAs medium with dimensions .By simulation the energy of exciton dependence with different molar coefficients, it was observed that: In sample, the exciton binding energy decreases with increasing molar coefficient. At a constant molar coefficient, the exciton dependence energy increases as the potential barrier width increases. At a constant molar coefficient, the exciton binding energy increases as the potential well width increases. پرونده مقاله -
دسترسی آزاد مقاله
6 - Thermodynamic Parameters of Cis-Platin and Trans-Platin Complexes with Guanine in Water, A DFT Study
F. R. Nikmaram M. Khan AhmadiThe binding energy and Thermodynamic Parameters of cis- Platinum Di Ammino Chlorine (cis-[Pt(NH3)2Cl]+) and trans- Platinum Di Ammino Chlorine (trans- [Pt(NH3)2Cl]+) complexes withGuanine has been studied by density functional theory (DFT) calculations in water. The bin چکیده کاملThe binding energy and Thermodynamic Parameters of cis- Platinum Di Ammino Chlorine (cis-[Pt(NH3)2Cl]+) and trans- Platinum Di Ammino Chlorine (trans- [Pt(NH3)2Cl]+) complexes withGuanine has been studied by density functional theory (DFT) calculations in water. The bindingenergies (Ebin) of cis- and trans-[Pt(NH3)2ClG]+ are calculated to be 79.38 kcal/mol and 74.98kcal/mol, respectively. The binding energy (Ebin) of cis-[Pt(NH3)2ClG]+ turns out to be energeticallymore favorable by about 1.88 kcal/mol than the trans-[Pt(NH3)2Cl]+. At the point of thermodynamic,the formation of cis-[Pt(NH3)2ClG]+(aq)with G (Solv) equal to -10.36 kcal/mol is more favorablethan trans-[Pt(NH3)2ClG]+(aq) with 16.21 kcal/mol. پرونده مقاله -
دسترسی آزاد مقاله
7 - Study on Sunitinib Adsorption on Graphene Surface as an Anticancer Drug
Sepideh Tanreh Abolghasem Shameli Ebrahim BalaliIn recent years, Nano technology and its application have moved to discovering chemicaltherapy drugs. Research, development for finding new targets in tumors, targeting methodsand stabilizing the nano particle in targeted cells is based on drug delivery and its cruciale چکیده کاملIn recent years, Nano technology and its application have moved to discovering chemicaltherapy drugs. Research, development for finding new targets in tumors, targeting methodsand stabilizing the nano particle in targeted cells is based on drug delivery and its crucialeffect. Examining the computational controlled drug delivery by graphene sheets has becomevery significant due to numerous side effects of this drug especially on nervous system as aresult of direct injection. In this work, adsorption of Sunitinib on Si and Al or nitrogen dopedgraphene has been studied using density functional theory. Doping Si or Al significantlyaffects the adsorption of Sunitinib over graphenes. Still, not much impact of doping Ni ongraphene is observed. Interaction energy, estimated using the super molecular approachranges from 54.97 KJ mol−1 to 63.95 KJ mol−1 in the gas phase. Furthermore, the calculateddensity of states (DOS) shows the existing of noteworthy orbital hybridization betweenSunitinib and Si or Al doped graphene during the adsorption process which is trying out tostrong interaction while there is no evidence for hybridization between the those moleculesand the pristine graphene. 11C and 1H chemical shielding correlate noticeably with thederivatives graphene. 11C, 27Al and 2H nuclear quadrupole coupling constants, CQ, andasymmetry parameter, η, reveal the remarkable effect of Sunitinib adsorption on electronicstructure of the graphene. پرونده مقاله -
دسترسی آزاد مقاله
8 - بررسی تئوری برهمکنش های بین بخش های حلقوی بعضی از داروها با نوکلئیک اسیدهای گوانین و آدنین: روش DFT، آنالیز AIM و محاسبات NBO
حسین عزیزی توپکانلو ضحی رحمانیروش تابعی چگال (DFT)، اتم در مولکول و روش NBO برای بررسی برهمکنش های π-π بین بخش های مختلف دارویی حلقوی شامل ایندول(I) ، بنزوتیوفن (Bt) و بنزوفوران(Bf) با گوانین (G) و آدنین (A) بکار گرفته شد. چندین کنفورمرمختلف از کمپلکس های تشکیل شده بین بخش های مختلف دارویی با چکیده کاملروش تابعی چگال (DFT)، اتم در مولکول و روش NBO برای بررسی برهمکنش های π-π بین بخش های مختلف دارویی حلقوی شامل ایندول(I) ، بنزوتیوفن (Bt) و بنزوفوران(Bf) با گوانین (G) و آدنین (A) بکار گرفته شد. چندین کنفورمرمختلف از کمپلکس های تشکیل شده بین بخش های مختلف دارویی با گوانین و آدنین توسط تابع M062X/6-311++G(d,p) بهینه شدند. نتایج نشان داد که کنفورمر IG1 و IA6 بیشترین پایداری را در بین تمام کنفورمرهای گوانین و آدنین دارند و ترتیب پایداری ها برای کمپلکس های گوانین به صورت IG1 > BtG6 > BfG1 و همچنین برای کمپلکس های آدنین به صورت IA6 > BtA6 > BfG6 می باشد. به علاوه، بررسی ما نشان داد که نتایج حاصل از روش DFT کاملا در تطابق با نتایج بدست آمده از آنالیز AIM می باشد. اما برعکس ارتباط مناسبی بین نتایج AIM و NBO مشاهده نگردید. پرونده مقاله -
دسترسی آزاد مقاله
9 - Kojic Acid Effect on the Inhibitory Potency of Tyrosinase
Forogh Azami Elham Tazikeh-Lemeski Mehr-Ali Mahmood-JanlouIn recent years, enzymatic activity of tyrosinase has been the focus of investigation due to its potential applications in medicine, agriculture and cosmetics. Tyrosinase, entitled polyphenol oxidase, is a key enzyme that catalyzes synthesis of melanin in plants, microo چکیده کاملIn recent years, enzymatic activity of tyrosinase has been the focus of investigation due to its potential applications in medicine, agriculture and cosmetics. Tyrosinase, entitled polyphenol oxidase, is a key enzyme that catalyzes synthesis of melanin in plants, microorganisms and mammalian cells. Presence of some antioxidants can delay or inhibit the activity of this enzyme as well. In this survey, molecular docking calculation method using Autodock 4.0 software for prediction of binding energy of the protein with some antioxidant ligands was executed. The pose with the lowest energy of binding or inhibition constant was extracted at 298.15 K for kojic acid. Number of conformations in the cluster of rank was 13. The first and second boxes free energy and the inhibition constant were as follows: -5.60 kcalmol-1, 78.99 µM and -3.32 kcalmol-1, 3.66 µM, respectively. Since the first box presented a lower value of free energy, it was considered as the best mode of structure of kojic acid and the protein docking for further analysis. Thus, our present study could contribute to development and discernment of tyrosinase inhibitors in order to prevent hyper pigmentation. پرونده مقاله
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