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991.
The Coulomb blockade (CB) in quantum dots (QDs) is by now well documented. It has been used to guide the fabrication of single
electron transistors. Even the most sophisticated techniques for synthesizing QDs (e.g. MOCVD/MBE) result in an assembly in
which a certain amount of disorder is inevitable. On the other hand, theoretical approaches to CB limit themselves to an analysis
of a single QD. In the present work we consider two types of disorders: (i) size disorder; e.g. QDs have a distribution of
sizes which could be unimodal or bimodal in nature. (ii) Potential disorder with the confining potential assuming a variety
of shapes depending on growth condition and external fields. We assume a Gaussian distribution in disorder in both size and
potential and employ a simplified mean field theory. To do this we rely on the scaling laws for the CB (also termed as Hubbard
U) obtained for an isolated QD [1]. We analyze the distribution in the Hubbard U as a consequence of disorder and observe that Coulomb blockade is partially suppressed by the disorder. Further, the distribution
in U is a skewed Gaussian with enhanced broadening.
相似文献
992.
Blue-emitting europium-ion-doped MgSrAl10O17 phosphor, prepared using the combustion method, is described. An efficient phosphor can be prepared by this method in a muffle furnace maintained at 500 °C in a very short time of few minutes. The phosphor is characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy and BET surface area measurements. Photoluminescence (PL) spectra revealed that europium ions were present in divalent oxidation state. The thermoluminescence (TL) glow curve shows two peaks at around 178 and at 354 °C. The defect centres formed in the phosphor are studied using electron spin resonance (ESR). The ESR spectrum indicates the presence of Fe3+ ions in the non-irradiated system. Irradiated MgSrAl10O17:Eu exhibits lines due to radiation-sensitive Fe3+ ion and a defect centre. The centre is characterized by an isotropic g-value of 2.0012 and is assigned to a F+ centre. The radiation-sensitive Fe3+ ion appears to correlate with the main TL peak at 178 °C. During irradiation an electron is released from Fe2+ and is trapped at an anion vacancy to form F+ centre. During heating, an electron is liberated from the defect centre and recombines with Fe3+ emitting light. 相似文献
993.
Vishal Sharma Raj Kumar Karan Devgan Pawan Kumar Mishra Adam Ekielski Vijay Kumar 《光谱学快报》2018,51(5):205-215
The multivariate analysis methods have recently gained high popularity within the field of forensic sciences because of their high accuracy and precision. The accurate and unbiased results are the preliminary need for a forensic investigation. The aim of the present work is to examine the marker pen inks which are widely used in various places like documentation in parcels, for photograph attestation, and also as a study material in the classroom. This research is focused on the three important aspects; first is to characterize the marker inks, second, to discriminate permanent marker and whiteboard marker inks using destructive (extracting of ink samples from paper substrate) and nondestructive (without ink extraction) techniques of ultraviolet–visible absorbance combined with peak identification examination as well as chemometric methods, and the third is to build a classification model for permanent and whiteboard marker inks. It is concluded that the chemometric method, that is, principal component analysis provides better discrimination power as compared to visual examination. However, destructive and nondestructive approaches give almost similar discriminating power. The classification model developed using linear discriminant analysis provides 87.5% of correct classification of marker ink samples. The method can further be used to formulate a statistical model for the determination of class/group of the other forensic exhibits. 相似文献
994.
995.
Nina Warner Ilja Gasan Osojnik rnivec Vijay Kumar Rana Menandro Cruz Oren A. Scherman 《Molecules (Basel, Switzerland)》2022,27(7)
The encapsulation of proteins into core-shell structures is a widely utilised strategy for controlling protein stability, delivery and release. Despite the recognised utility of these microstructures, however, core-shell fabrication routes are often too costly or poorly scalable to allow for industrial translation. Furthermore, many scalable routes rely upon emulsion-techniques implicating denaturing or environmentally harmful organic solvents. Herein, we investigate core-shell protein encapsulation through single-feed, aqueous spray drying: a cheap, industrially ubiquitous particle-formation technology in the absence of organic solvents. We show that an excipient’s preference for the surface of the spray dried particle is well-predicted by its hydrodynamic diameter (D) under relevant feed buffer conditions (pH and ionic strength) and that the predictive power of D is improved when measured at the spray dryer outlet temperature compared to room temperature ( = 0.64 vs. 0.59). Lastly, we leverage these findings to propose an adaptable design framework for fabricating core-shell protein encapsulates by single-feed aqueous spray drying. 相似文献
996.
Vijay Nair Tesmol G. George Anu Augustine Latha G. Nair 《Research on Chemical Intermediates》2000,26(9):923-929
Various 1,3-dienes when treated with a solution of cerium(IV) ammonium nitrate and ammonium thiocyanate in acetonitrile afforded
the isothiocyanatothiocyanates via a [3,3] sigmatropic rearrangement. Electron rich dienes afforded the γ-thiocyanato-α,β-unsaturated carbonyl compounds under similar experimental conditions. 相似文献
997.
Plant-based nanoparticles (NPs) have found great interest among various scientist in the present era and used in various sector including medicine, agriculture, and food industry. The various chemical constituents of plants aid in the bioreduction of metal ions to a nanoscale. Among the various NPs synthesized, zinc oxide (ZnO) NPs hold a premier position. ZnO NPs have use in textile, cosmetic, diagnostics, optoelectronics, photocatalysis, diodes, and many other areas. NPs synthesized through green synthesis have a potentially greater role in treating clinical pathogens. Present investigations show a simple eco-friendly method for the synthesis of ZnO NPs from the husk of sunflower seeds. Sunflower is an economically important crop, for the formation of edible oil. The husk is considered to be a waste, product in oil industry, however, the biomolecules present in sunflower husk can be used to produce ZnO NPs. Present investigations reveal formation of ZnO NPs and investigations of their structure through scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Their optical properties have been studied by ultraviolet–visible spectrophotometer (UV–Vis) and fluorophotometer. ZnO NPs have also been investigated for their potential phytoremedial properties. 相似文献
998.
Vijay Singh Paul Mathias Masanja Apoorva Dwivedi Ashutosh Tiwari Anoop Kumar Pandey 《Macromolecular Symposia》2024,413(1):2300085
In the present communication, the interaction of single-wall carbon nanotubes (SWCNTs) CNT (C56H16) with endohedral doped superhalogens (MF4:M = B, Al) placed outside of CNT cage and superalkali (Na2F) placed inside the cage has been studied by using a combination of DFT/B3LYP method and 6–311G(d, p) basis set. The geometry and stability of MF4@CNT-Li2F have been studied using optimization parameters, highest occupied molecular orbit (HOMO), lowest unoccupied molecular orbital (LUMO), vibration frequencies, and thermodynamic parameters of absorption reactions. The quantum theory in atoms in molecules (QTAIM) analysis is used to analyze the nature of interactions between MF4 (M = B, Al) and Na2F@CNT. Several electronic parameters are computed by using HOMO–LUMO energy. The dipole moment, polarizability, hyperpolarizability, order parameters, anisotropic polarizability, and molar refractivity of MF4@CNT-Li2F (M = Al, B) are used to calculate the nonlinear optical parameters (MR). The NBO analysis is used to calculate the transfer of charge to stabilized system. The calculated hyperpolarizability of Na2F@CNT-BF4/Na2F@CNT-AlF4 is nearly 81 times that of reference material urea (40 a.u.). The intramolecular charge transfer (ICT) moment of π electron cloud is responsible for the nonlinear optical behavior of the system. 相似文献
999.
1000.