scholarly journals Role of local fields in the optical properties of silicon nanocrystals using the tight binding approach

2007 ◽  
Vol 75 (3) ◽  
Author(s):  
F. Trani ◽  
D. Ninno ◽  
G. Iadonisi
Keyword(s):  
Optical Properties ◽  
Silicon Nanocrystals ◽  
Tight Binding ◽  
Local Fields

The Role of Local Fields in the Optical Properties of Silicon Nanocrystals

2006 ◽  
Vol 958 ◽  
Author(s):  
Fabio Trani ◽  
Domenico Ninno ◽  
Giovanni Cantele ◽  
Giuseppe Iadonisi
Keyword(s):  
Optical Properties ◽  
Local Field ◽  
Silicon Nanocrystals ◽  
Tight Binding ◽  
Visible Spectral Range ◽  
Local Fields ◽  
Strong Suppression ◽  
Field Effects ◽  
Dielectric Model

ABSTRACTIn this paper we discuss the role of local fields in the optical properties of silicon nanocrystals. Using a semiempirical tight binding approach, local field effects are included into the linear response theory, going beyond the standard independent particle approximation. The results show that local field effects give an important contribution to the optical properties of silicon nanocrystals, leading to a strong suppression of the absorption in the visible spectral range. This effect is attributed to the classical surface polarization contribution. A comparison between the atomistic tight binding approach and a classical dielectric model shows that the dielectric model gives reasonable results not only for large, but even for small silicon nanocrystals.

Electronic, structural and optical properties of hydrogenated silicon nanocrystals: the role of the excited states

2005 ◽  
Vol 2 (9) ◽  
pp. 3263-3267 ◽  
Author(s):  
G. Cantele ◽  
Elena Degoli ◽  
Eleonora Luppi ◽  
Rita Magri ◽  
D. Ninno ◽  
...  
Keyword(s):  
Optical Properties ◽  
Excited States ◽  
Silicon Nanocrystals ◽  
Structural And Optical Properties ◽  
Hydrogenated Silicon

Tight binding calculations for the optical properties of ellipsoidal silicon nanocrystals

2005 ◽  
Vol 2 (9) ◽  
pp. 3435-3439 ◽  
Author(s):  
F. Trani ◽  
G. Cantele ◽  
D. Ninno ◽  
G. Iadonisi
Keyword(s):  
Optical Properties ◽  
Silicon Nanocrystals ◽  
Tight Binding

Photoluminescence behavior of silicon nanocrystals: Role of surface chemistry and size

2008 ◽  
Author(s):  
Anoop Gupta ◽  
Folarin Erogbogbo ◽  
Mark T. Swihart ◽  
Hartmut Wiggers
Keyword(s):  
Surface Chemistry ◽  
Silicon Nanocrystals ◽  
Photoluminescence Behavior

scholarly journals Cystatin M/E (Cystatin 6): A Janus-Faced Cysteine Protease Inhibitor with Both Tumor-Suppressing and Tumor-Promoting Functions

Cancers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1877
Author(s):  
Gilles Lalmanach ◽  
Mariana Kasabova-Arjomand ◽  
Fabien Lecaille ◽  
Ahlame Saidi
Keyword(s):  
Prognostic Significance ◽  
Tight Binding ◽  
Cysteine Protease Inhibitor ◽  
Tumor Promoter ◽  
Regulatory Mechanisms ◽  
Placental Development ◽  
Cysteine Cathepsins ◽  
Cystatin M

Alongside its contribution in maintaining skin homeostasis and its probable involvement in fetal and placental development, cystatin M/E (also known as cystatin 6) was first described as a tumor suppressor of breast cancer. This review aims to provide an update on cystatin M/E with particular attention paid to its role during tumorigenesis. Cystatin M/E, which is related to type 2 cystatins, displays the unique property of being a dual tight-binding inhibitor of both legumain (also known as asparagine endopeptidase) and cysteine cathepsins L, V and B, while its expression level is epigenetically regulated via the methylation of the CST6 promoter region. The tumor-suppressing role of cystatin M/E was further reported in melanoma, cervical, brain, prostate, gastric and renal cancers, and cystatin M/E was proposed as a biomarker of prognostic significance. Contrariwise, cystatin M/E could have an antagonistic function, acting as a tumor promoter (e.g., oral, pancreatic cancer, thyroid and hepatocellular carcinoma). Taking into account these apparently divergent functions, there is an urgent need to decipher the molecular and cellular regulatory mechanisms of the expression and activity of cystatin M/E associated with the safeguarding homeostasis of the proteolytic balance as well as its imbalance in cancer.

scholarly journals Role of the Anilinium Ion on the Selective Polymerization of Anilinium 2-Acrylamide-2-methyl-1-propanesulfonate

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2349
Author(s):  
Alain Salvador Conejo-Dávila ◽  
Marco Armando Moya-Quevedo ◽  
David Chávez-Flores ◽  
Alejandro Vega-Rios ◽  
Erasto Armando Zaragoza-Contreras
Keyword(s):  
Cyclic Voltammetry ◽  
Optical Properties ◽  
Thermal Properties ◽  
Free Radical ◽  
1H Nmr ◽  
Molecular Interactions ◽  
13C Nmr ◽  
Oxidative Polymerization ◽  
Cyclic Voltammetry Analysis

The development of anilinium 2-acrylamide-2-methyl-1-propanesulfonate (Ani-AMPS) monomer, confirmed by 1H NMR, 13C NMR, and FTIR, is systematically studied. Ani-AMPS contains two polymerizable functional groups, so it was submitted to selective polymerization either by free-radical or oxidative polymerization. Therefore, poly(anilinium 2-acrylamide-2-methyl-1-propanesulfonic) [Poly(Ani-AMPS)] and polyaniline doped with 2-acrylamide-2-methyl-1-propanesulfonic acid [PAni-AMPS] can be obtained. First, the acrylamide polymer, poly(Ani-AMPS), favored the π-stacking of the anilinium group produced by the inter- and intra-molecular interactions and was studied utilizing 1H NMR, 13C NMR, FTIR, and UV-Vis-NIR. Furthermore, poly(Ani-AMPS) fluorescence shows quenching in the presence of Fe2+ and Fe3+ in the emission spectrum at 347 nm. In contrast, the typical behavior of polyaniline is observed in the cyclic voltammetry analysis for PAni-AMPS. The optical properties also show a significant change at pH 4.4. The PAni-AMPS structure was corroborated through FTIR, while the thermal properties and morphology were analyzed utilizing TGA, DSC (except PAni-AMPS), and FESEM.

scholarly journals Effect of dopant concentration and the role of ZnS shell on optical properties of Sm3+ doped CdS quantum dots

RSC Advances ◽  
2021 ◽  
Vol 11 (14) ◽  
pp. 7961-7971
Author(s):  
N. D. Vinh ◽  
P. M. Tan ◽  
P. V. Do ◽  
S. Bharti ◽  
V. X. Hoa ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Dopant Concentration ◽  
Core Shell ◽  
Cds Quantum Dots ◽  
Cds Qds

The role of samarium (Sm) dopant on the structural, morphological, and optical properties of CdS QDs and CdS/ZnS core/shell QDs was methodically reported.

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