Numerical Analysis on Phonon Localization of Vacancy Type Disordered Graphene

2014 ◽  
Vol 24 (02) ◽  
pp. 1540002 ◽  
Author(s):  
Md. Sherajul Islam ◽  
Md. Tawabur Rahaman ◽  
Ashraful Ghani Bhuiyan ◽  
Akihiro Hashimoto
Keyword(s):  
Defect Density ◽  
Localization Length ◽  
System Size ◽  
Vacancy Defects ◽  
High Concentrations ◽  
Phonon Localization ◽  
Localized Vibrations ◽  
Typical Mode ◽  
Phonon Properties ◽  
Good Agreement

The phonon properties of hydrogen passivated graphene with vacancy defects are studied using the forced vibrational method. The phonon density of states (PDOSs), typical mode patterns and localization length are calculated over a broad range of vacancies. We find that phonon properties of graphene strongly depend on the system size. We observe a broadening and softening of the PDOS peaks with the increase of vacancy concentrations. We find an increasing C – H stretching mode with the increase of defect density. Our numerical experiments reveal that the typical mode pattern for the K point in-plane TO (iTO) modes phonon show the spatial localized vibrations persuaded by vacancies, which are in conceptually good agreement with the large D band peak of the Raman spectra comes from the imperfections of crystal. For the K point iTO mode phonons, a typical localization length is on the order ≈ 5 nm for vacancy-type defects at high concentrations of 30% is observed. The localization effects manifest themselves in the projected temperature behavior of the constant-volume specific heat capacity of pristine and disordered graphene samples.

Cultivation of New Emerging Agro-Nutritional Crop of Quinoa at Madinat al-Hikmah Karachi, Sindh, Pakistan

2017 ◽  
Vol 10 (1) ◽  
pp. 70-81 ◽  
Author(s):  
Muhammad Afzal Rizvi ◽  
Syed Abid Ali ◽  
Iqra Munir ◽  
Kousar Yasmeen ◽  
Rubina Abid ◽  
...  
Keyword(s):  
Arid Zone ◽  
Good Health ◽  
Morphological Characters ◽  
Morphological Data ◽  
Low Concentrations ◽  
Sindh Province ◽  
High Concentrations ◽  
Elemental Accumulation ◽  
Semi Arid ◽  
Good Agreement

Aim: Quinoa is a popular source of protein, minerals and alternative to traditional grains. The objective of this study is to introduce the Quinoa in the semi-arid zone of Sindh province of Pakistan. Method: A variety of NARC-9 from the agricultural Punjab province was cultivated and subjected to analyze the growth, morphological characters of the varieties obtained, saponin, protein and the elemental composition viz. Cd, Cu, Fe, K, Na, Pb, and Zn. Result: The result demonstrated the optimum growth and no disease were found in the experimental area. At least three major varieties of quinoa were obtained. Seed morphological data of these three quinoa cultivars were collected. The average saponin levels were quite reasonable. Overall proteins band pattern revealed very high polymorphism in quinoa cultivars and the results were also in good agreement with earlier studies. Conclusion: All quinoa cultivars of Madinat al-Hikmah showed high concentrations of albumin than globulin concentrations (i.e. 48-52% and 24-27%, respectively) as compared to control seeds from market that had similar concentrations of the two fractions i.e. 35.58% and 37.68%, respectively. Likewise, low concentrations of prolamin 14-16% and glutelin 11-12% compared to control seeds 13% rank our crop much better quality than the imported one in the market. The trend of elemental accumulation was followed as K >Na >Fe >Zn >Cu >Pb >Cd, while for comparison it was Na >K >Zn >Fe >Cu >Pb >Cd >Pb for wheat grown under similar conditions. Traditional grains together make a major contribution to the total nutritional element intake of the average Pakistani citizen through diet, not only because of large amounts consumed, but also in part by suitable levels of their proteins and elemental up take for good health. Thus the successful cultivation of quinoa in the semi-arid zone of Sindh will certainly prove beneficial.

scholarly journals Millisecond lattice gasification for high-density CO2- and O2-sieving nanopores in single-layer graphene

2021 ◽  
Vol 7 (9) ◽  
pp. eabf0116
Author(s):  
Shiqi Huang ◽  
Shaoxian Li ◽  
Luis Francisco Villalobos ◽  
Mostapha Dakhchoune ◽  
Marina Micari ◽  
...  
Keyword(s):  
Single Layer ◽  
High Density ◽  
Single Layer Graphene ◽  
Pore Density ◽  
Vacancy Defects ◽  
Carbon Gasification ◽  
Layer Graphene ◽  
Gas Molecules ◽  
Good Agreement

Etching single-layer graphene to incorporate a high pore density with sub-angstrom precision in molecular differentiation is critical to realize the promising high-flux separation of similar-sized gas molecules, e.g., CO2 from N2. However, rapid etching kinetics needed to achieve the high pore density is challenging to control for such precision. Here, we report a millisecond carbon gasification chemistry incorporating high density (>1012 cm−2) of functional oxygen clusters that then evolve in CO2-sieving vacancy defects under controlled and predictable gasification conditions. A statistical distribution of nanopore lattice isomers is observed, in good agreement with the theoretical solution to the isomer cataloging problem. The gasification technique is scalable, and a centimeter-scale membrane is demonstrated. Last, molecular cutoff could be adjusted by 0.1 Å by in situ expansion of the vacancy defects in an O2 atmosphere. Large CO2 and O2 permeances (>10,000 and 1000 GPU, respectively) are demonstrated accompanying attractive CO2/N2 and O2/N2 selectivities.

Mechanism of Action of Progestins in the Treatment of Hormone-dependent Breast Cancer.

1975 ◽  
Vol 61 (6) ◽  
pp. 501-508 ◽  
Author(s):  
Francesco Di Carlo ◽  
Giovanni Pacilio ◽  
Giuseppe Conti
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptors ◽  
Mechanism Of Action ◽  
Mode Of Action ◽  
Binding Capacity ◽  
Specific Receptors ◽  
High Concentrations ◽  
Good Agreement

The in vitro interference of some gestagens with the binding of 3H-17 β-oestradiol to cytosol specific receptors was investigated with a view to elucidating the mechanism of action of progestins in the treatment of human hormone-dependent breast cancer. A decrease (up to 85 %) of oestradiol binding capacity was observed with high concentrations of progesterone, clogestone and medrogestone. These findings are in good agreement with those previously obtained by the same progestins in our laboratory on rat uterine estrogen receptors in vitro or in vivo. These results provide support for the hypothesis that the mode of action of progestins in the therapy of mammary and perhaps uterine carcinomas is to some extent related to the inhibition of oestradiol binding to cytosol specific receptors.

scholarly journals Structural Modifications in Epitaxial Graphene on SiC Following 10 keV Nitrogen Ion Implantation

2020 ◽  
Vol 10 (11) ◽  
pp. 4013
Author(s):  
Priya Darshni Kaushik ◽  
Gholam Reza Yazdi ◽  
Garimella Bhaskara Venkata Subba Lakshmi ◽  
Grzegorz Greczynski ◽  
Rositsa Yakimova ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Ion Implantation ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Defect Density ◽  
Epitaxial Graphene ◽  
Monolayer Graphene ◽  
Vacancy Defects ◽  
Nitrogen Ion Implantation ◽  
Nitrogen Ion

Modification of epitaxial graphene on silicon carbide (EG/SiC) was explored by ion implantation using 10 keV nitrogen ions. Fragments of monolayer graphene along with nanostructures were observed following nitrogen ion implantation. At the initial fluence, sp3 defects appeared in EG; higher fluences resulted in vacancy defects as well as in an increased defect density. The increased fluence created a decrease in the intensity of the prominent peak of SiC as well as of the overall relative Raman intensity. The X-ray photoelectron spectroscopy (XPS) showed a reduction of the peak intensity of graphitic carbon and silicon carbide as a result of ion implantation. The dopant concentration and level of defects could be controlled both in EG and SiC by the fluence. This provided an opportunity to explore EG/SiC as a platform using ion implantation to control defects, and to be applied for fabricating sensitive sensors and nanoelectronics devices with high performance.

CPM and PDS - A Critical Interpretation of Experimental Results

1996 ◽  
Vol 420 ◽  
Author(s):  
Helmut Stiebig ◽  
Frank Siebke ◽  
Reinhard Carius
Keyword(s):  
Defect Density ◽  
Optical Transitions ◽  
Defect States ◽  
Defect Distribution ◽  
Urbach Tail ◽  
Yield Information ◽  
Pool Model ◽  
Neutral Defect ◽  
Critical Interpretation ◽  
Good Agreement

AbstractCPM and PDS spectra of a-Si:H yield identical shape of the Urbach tail, while the defect absorption measured by PDS differs significantly from CPM. In this work an analysis of CPM and PDS spectra of annealed and degraded films is presented. Numerical simulations of CPM and PDS data, taking into account optical transitions, capture and emission processes as well as the Fermi level, yield information on the energy distribution and the charge state of the defects. The simulations reveal the coexistence of defects in the D−, D+ and D0 states. The defect distribution is dominated by charged states as predicted by the defect-pool model. Good agreement between measured and simulated PDS and CPM spectra can be obtained in the case of a homogeneous defect density. It is shown that differences between CPM and PDS are due to different sensitivities of the techniques to charged and neutral defect states. Microscopic inhomogeneities may cause significant additional differences.

LATTICE DYNAMICS OF MBa2Cu3O7(M=Y, Gd) and YBa2Cu3O6

1989 ◽  
Vol 03 (08) ◽  
pp. 1277-1286 ◽  
Author(s):  
JIE QIN ◽  
YIMIN JIANG
Keyword(s):  
Density Of States ◽  
Phonon Dispersion ◽  
Experimental Investigations ◽  
Phonon Density ◽  
Phonon Density Of States ◽  
Phonon Dispersion Curves ◽  
Rare Earth Atom ◽  
Range Overlap ◽  
Phonon Properties ◽  
Good Agreement

We have presented a lattice dynamical calculation of phonon dispersion curves and one-phonon density of states for the high-T c superconducting MBa 2 Cu 3 O x (M=Y, Gd : x=7, 6) compounds. The model we used is in the framework of a rigid-ion model which includes long-range Coulomb potential and a short-range overlap. The results of calculation give quite good agreement with the available Raman and infrared data, and the measurements of phonon density of states. These results therefore can serve as a guide for further experimental investigations of the phonon properties in M-Ba-Cu-O (M=rare earth atom) system.

DIFFUSION IN MULTICOMPONENT AQUEOUS SYSTEMS

1966 ◽  
Vol 44 (4) ◽  
pp. 477-485 ◽  
Author(s):  
J. E. Lane ◽  
J. S. Kirkaldy
Keyword(s):  
Aqueous Solutions ◽  
Relative Viscosity ◽  
Ionic Species ◽  
Aqueous Systems ◽  
Vacancy Model ◽  
High Concentrations ◽  
Substitutional Alloys ◽  
Good Agreement

A vacancy model, originally developed for the description of diffusion in substitutional alloys, is modified for application to aqueous solutions, including those containing ionic species. The results obtained with this model are similar to those of two recently published methods for estimating L-coefficients in dilute multicomponent liquid systems.Agreement with experimental L-coefficients at relatively high concentrations can be improved for this model by assuming that the jump probability of a diffusing species is inversely proportional to the relative viscosity of the mixture. Good agreement is then found for some systems up to combined solute concentrations of 3 M.

Effect of vacancy defects on phonon properties of hydrogen passivated graphene nanoribbons

Carbon ◽  
2014 ◽  
Vol 80 ◽  
pp. 146-154 ◽  
Author(s):  
Md. Sherajul Islam ◽  
Satoru Tanaka ◽  
Akihiro Hashimoto
Keyword(s):  
Graphene Nanoribbons ◽  
Vacancy Defects ◽  
Phonon Properties

scholarly journals Simulation Analyses and Investigation of the Induced Electric Field and Ar-Hg Mixture on the Gas Discharge Processes

2020 ◽  
Vol 31 (3) ◽  
pp. 126
Author(s):  
Fatima Mohammad Hadi ◽  
Rafid Abbas Ali ◽  
Ahamed A. Al-Rubaiee
Keyword(s):  
Electric Field ◽  
Theoretical Calculations ◽  
Simulated Data ◽  
Original Data ◽  
Limited Range ◽  
Gas Discharges ◽  
Electronic Transactions ◽  
Low Levels ◽  
High Concentrations ◽  
Good Agreement

In this work, theoretical calculations and simulated data were presented to investigate the effect of the Ar: Hg mixture on electronic plasma coefficients, in addition to study the influence of the electric field and focus on electronic coefficients. The low electric field was chosen in the range (1-1000) Td, and concentrations in a limited range (0.01-0.09) mol. The results showed a clear effect of the electric field on electronic transactions, especially at low levels. These parameters values are higher for high concentrations due to the effect of the electric field on the excitation and ionization energy. In compare to elastic and inelastic collision, and cross-section collision of gas discharges. The results showed good agreement between the original data (using BOLSIG +) and the estimated data in the current work.

Agonist Anti-TRAILR1 Human Mab, Hgs-ETR1, Induces Myeloma Cell Death Mainly through the Intrinsic Pathway of Apoptosis.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1713-1713
Author(s):  
Emmanuelle Ménoret ◽  
Sylvanie Surget ◽  
Patricia Gomez-Bougie ◽  
Régis Bataille ◽  
Martine Amiot ◽  
...  
Keyword(s):  
Cell Death ◽  
Specific Inhibitor ◽  
Myeloma Cell ◽  
Intrinsic Pathway ◽  
Mitochondrial Depolarization ◽  
Caspase 9 ◽  
Myeloma Cells ◽  
High Concentrations ◽  
Induced Apoptosis ◽  
Good Agreement

Abstract We previously reported that agonist anti-TRAILR mAbs (HGS-ETR1) induced cell death of myeloma cells through both the extrinsic and intrinsic pathway. Although caspase 8 activation was fully required to initiate death signaling, it was unclear whether intrinsic pathway played or not a major role in apoptosis execution. In the current work, we evaluated the contribution of the intrinsic pathway in a large panel of HMCL (n=10). To address this question, we monitored mitochondrial depolarization and the contribution of caspase 9. Apoptosis and mitochondrial polarization were both evaluated by flow cytometry. Kinetic analysis of mitochondrial polarization (JC-1) shows that all mitochondria were fully depolarized after only 4h following HGS-ETR1 mAb addition: the depolarization started early, as soon as 1h. In good agreement with mitochondrial depolarization, we observed that specific inhibitor of caspase 9 activity (z-LEHD-fmk) always prevented at least 50% of death (and up to 90%). Our data show that in all cell lines evaluated, activation of the intrinsic pathway was required for cell death even with high concentrations of mAb. We previously showed that anti-TRAILR apoptosis was always associated with an early and massive Mcl-1 cleavage (Menoret et al Blood2006, 108:1346). In myeloma cells, Mcl-1 is physically associated with Bim and thus prevents Bim to induce mitochondrial cell death (Gomez-Bougie EJI 2004, 34;3156). By immunoprecipitation, we show that, in the presence of HGS-ETR1 mAb, Mcl-1/Bim complexes were disrupted and Bim was free to activate Bax. Bim is also found to be complexed to both Bcl-XL and Bcl-2 in viable cells. During anti-TRAILR mAb induced apoptosis, Bcl-2 and Bcl-XL were also cleaved and full length Bcl-XL, as Mcl-1, fully disappeared indicating that BcL-XL decrease probably participated to the increase of free Bim. Furthermore, immunoprecipitation of Bax showed that Bax was associated with Bcl-2 (and not with Mcl-1 or Bcl-XL) and this association was reduced in apoptotic conditions. These data show that apoptosis induced by anti-TRAILR mAb mainly involved the intrinsic pathway through disruption of both anti-apoptotic/Bim and Bcl-2/bax complexes. This result suggests that the association of anti-TRAILR mAb with melphalan or bortezomib would not synergistically increase anti-TRAILR mAb efficiency and that anti-TRAILR mAb should be rather combined with drugs acting independently of the intrinsic pathway.

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