Thermoelectric power in carbon nanotubes and quantum wires of nonlinear optical, optoelectronic, and related materials under strong magnetic field: Simplified theory and relative comparison
Summary (3 min read)
- Notch signalling is a local cell communication mechanism highly conserved throughout the animal kingdom.
- Nicd is the active form of the receptor and acts in the nucleus as a transcriptional regulator, in cooperation with the DNA-binding protein CSL (also known as Su(H), CBF1 and LAG-1) and its co-activator Mastermind (Bray, 2006).
- As in mammals, Notch activity is required to prevent premature differentiation of the AMPs, which are specified in the embryo and ultimately give rise to the adult muscles of the fly.
- At the target sites, myoblasts fuse with templates formed either from founder myoblasts or, in a few cases, from persistent larval muscles.
- Thus, these data support the model that Notch activity has the potential to directly regulating genes that co-ordinate cell morphology, in addition to its more widely accepted role in regulating such characteristics through cell fate-determining transcription factors.
- Identification of Notch target genes involved in adult myogenesis.
- Thus overall it seems likely that the flightless phenotype itself is due to subtler defects in muscle function and that there are also perturbations at earlier developmental stages that correlate to lethality before the flies eclose.
- Thus, Reck, talin and trio are all expressed in AMPs, consistent with their proposed function in adult myogenesis.
- Indeed, shortened Reck NRE was no longer responsive to Nicd, suggesting there are relevant Su(H) motifs in the larger fragment which would explain the residual activity of the mutated long Reck NRE.
- Finally, the authors tested whether the expression from the Reck and talin NREs were affected when Notch signalling was compromised.
- Notch signalling is widely implicated in the control of cell fate during development but also has been shown to influence cell architecture and behaviour in different morphogenetic processes.
- In most cases, Notch is proposed to co-ordinate cell morphogenesis by regulating the expression of key transcription factors, rather than by directly regulating the effector genes that implement the cell behaviours (Niessen et al., 2008; Saad et al., 2010; Schober et al., 2005; Wang et al., 2007).
- Two of the three genes, trio and talin, are very widely expressed.
- The identified NRE directs expression in these cells, consistent with Reck expression being controlled by Notch activity in AMPs.
- Two of these, corn and unc-5, were previously shown to be expressed in AMPs.
MATERIALS AND METHODS
- Fly stocks used for RNAi experiments are from BDSC (Bloomington, Indiana, USA), DRGC (Kyoto, Japan) or VDRC (Vienna, Austria).
- Individual line numbers are indicated in table S1.
- Crosses were culture at 25°C and progeny was assayed for its ability to fly.
- For the phenotype observed with trio, discs were scored on the basis of whether the AMP cells were abnormally dispersed, with gaps evident.
- For each RNAi line tested, at least 40 adult flies aged 2-8 days were assayed for their ability to fly.
- For this, flies were dump dropped from their vials at approximately 50 cm from the bench and numbers of flies that fell on the bench were scored (i.e. flies that could not fly away).
- This test was repeated twice from independent crosses and the results were averaged.
- Finally, genes with lines giving very different results (e.g. “weak and “strong”) were classified as “uncertain”.
- Thoraces were cut sagittally, mounted in glycerol and viewed under polarized light.
Luciferase experiments and GFP reporters.
- For luciferase assays, putative NRE fragments from Reck, rhea/talin and trio were amplified from Drosophila genomic DNA using primers containing restriction enzyme sequences and cloned into a luciferase vector containing a minimal promoter from the hsp70 gene (pGL3::Min).
- The authors also used rabbit anti-GFP (1:500, Life Technologies.
- In situ hybridization was performed according to standard protocol.
- Wing imaginal discs from third instar control (1151-Gal4) and Notch depleted (1151>N-RNAi) larvae were dissected (20 discs for each genotype).
- Dorsal halves (corresponding to the notum, where the AMPs are located) were separated from the wing pouch and used for RNA extraction using TRIzol (Life Technologies).
- Genomic DNA was eliminated using Ambion’s DNA-free kit.
- CDNA was synthesized using random hexamers (Promega.
- Ef2: Fwd GCCGATCTGCGCTCTAATAC, Rev ACGAGTATCCTGGACGATGG, within exon 5; Notch: Fwd TGCGATGTTCAGACGATTTC, Rev CGTATCCCTGGGAGCAGTAG, within exon 5; Reck: Fwd TGGACCAAAACTCGACACTG, Rev TACTCCTAGGCGGACAATGC, within exon 8; talin: Fwd CAGCAGCAGTGAACTTGGAG, Rev CTGGGTCATCGAGGTGAGTC, within exon 15; trio Fwd 16 ACCCATGAAAAGGACGTGAC, Rev CTCTCCTGCTGATCCCTCTG, within exon 4 of the longest isoform.
- The authors are grateful to Alexis Lalouette for the E(spl)m6-Gal4 line, to Renate Renkawitz- Pohl for the beta3-tubulin antibody, to Nick Brown for Talin antibody and to Bruce Paterson for Mef2 antibody.
- The authors also acknowledge the Bloomington Stock Center (BL), Vienna Drosophila RNAi Center (VDRC), The Kyoto Stock Center (DGRC) and The Developmental Studies Hybridoma Bank (DSHB) for providing Drosophila strains and antibodies.
- The authors thank members of the Bray lab for valuable discussions.
- This work was supported by a programme grant from the Medical Research Council to SJB [G0800034], by fellowships to GP from Fondation pour la Recherche Medical and from Marie Curie (Intra European Fellowship [PIEF-GA-2009-236426]) and by an EMBO Long Term Fellowship to HB [ALTF 325-2013].
- An RNAi assay identifies genes required for muscle formation.
- Plain bars represent wildtype fragments and striped bars fragments in which Su(H) sites were mutated.
- Maximum projections of z-stacks from confocal acquisitions are presented.
- Late third instar larval stage (wandering larvae), also known as L3b.
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Frequently Asked Questions (11)
Q1. What are the contributions mentioned in the paper "Thermoelectric power in carbon nanotubes and quantum wires of nonlinear optical, optoelectronic, and related materials under strong magnetic field: simplified theory and relative comparison" ?
The authors study thermoelectric power under strong magnetic field TPM in carbon nanotubes CNTs and quantum wires QWs of nonlinear optical, optoelectronic, and related materials. In addition, the authors have suggested the experimental methods of determining the Einstein relation for the diffusivity-mobility ratio and the carrier contribution to the elastic constants for materials having arbitrary dispersion laws.
Q2. What is the effect of the change in the TPM?
With varying electron concentration, a change is reflected in the TPM through the redistribution of the electrons among the quantized levels.
Q3. What is the Einstein relation for the transport properties of semiconductor devices?
The simplest way of analyzing such devices taking into account the degeneracy of bands is to use the appropriate Einstein relation to express the performance at the device terminals and switching speed in terms of carrier concentration.
Q4. What is the effect of quantum confinement on the TPM?
With large values of film thickness, the height of the steps decreases and the TPM decreases with increasing electron statistics in a nonoscillatory manner.
Q5. What is the Einstein relation for the diffusivity-mobility ratio?
It is well known that the Einstein relation for the diffusivity-mobility ratio D / is an important quantity for studying the transport properties of semiconductor devices since the diffusion constant a quantity very useful for device analysis but whose exact experimental determination is rather difficult can be derived from this ratio if one knows the experimental values of the mobility.
Q6. What is the Einstein relation for the mechanical properties of the materials in nanotechnology?
The knowledge of the carrier contribution to the elastic constants C44 and C456 is very important in studying the mechanical properties of the materials in nanotechnology, and has been investigated extensively in the literature.
Q7. What is the TPM for the QWs of n-GaSb?
Investigation of the TPM for the QWs of n-GaSbThe dispersion relation of the conduction-band electrons in bulk specimens of n-GaSb can be written as111E = − Eg 2 + Eg 2 1 + 0k2 1/2 + 02k22mo+ v0f1 k 22mo0f2 k 22mo , 49where 0=4P 2 Eg+ 23 Eg 2 Eg+ −1, P is the momentum matrix element, f1 k =k−2 kx 2ky 2+ky 2kz 2+kz 2kx 2 represents the warping of the Fermi surface, f2 k = k2 kx 2ky 2+ky 2kz 2+kz 2kx2 −9kx 2ky 2kz2 1/2k−1 represents the inversion asymmetry splitting of the conduction band, and 0, v0, and 0 represent the constants of the electron spectrum in this case.
Q8. What is the TPM of the three-band model of Kane?
Using Eqs. 17 , 18 , 20 , 21 , 23 , and 24 , in Figs. 2 a –2 e the authors have plotted the TPM as a function of the film thickness for QWs of n-InAs, n-GaAs, n-InSb, Hg1−xCdxTe, and In1−xGaxAsyP1−y lattice matched to InP, in which the plots a , b , and c represent the three-band model of Kane, the two-band model of Kane, and that of the parabolic energy band, respectively.
Q9. What is the Einstein relation for the second- and third-order elastic constants?
116 The electronic contribution to the second- and third-order elastic constants can be written as116C44 = − G029 n0 EF73andC456 = G0327 2n0 EF
Q10. What are the TPM values for the three different types of QWs?
Using Eqs. 38 , 39 , 42 , 43 , 47 , 48 , 52 , and 53 , the authors have plotted in Figs. 5 a and 5 b the TPM as a function of film thickness and electron concentration per unit length for QWs of stressed n-InSb a and b represent the plots both in the presence and absence of stress , n-GaP curve c , PtSb2 curve d , and n-GaSb curve e , respectively.
Q11. What is the TPM of the QWs of the three-band model of Kane?
Using Eqs. 30 , 31 , 34 , and 35 , in Figs. 4 a and4 b the authors have plotted the TPM as a function of film thickness and electron concentration per unit length for QWs of II-VI and IV-VI materials, respectively, where the plot b refers to p-CdS in accordance with the Hopfield model with C0 0 eV m, while the plot a corresponds to the same for C0=0 eV m for the purpose of assessing the influence of thesplitting of the two-spin states by the spin-orbit coupling and the crystalline field in this case.