Review of the Structural Stability, Electronic and Magnetic Properties of Nonmetal-Doped TiO2_2 from First-Principles Calculations

This paper reviews and summarizes the recent first-principles theoretical studies of the structural stability, electronic structure, optical and magnetic properties of nonmetal-doped TiO$_2$. The first section presents a comparison study of the structural stability for X-anion and X-cation doped TiO$_2$ (X=B, C, Si, Ge, N, P, As, Sb, S, Se, Te, F, Cl, Br, and I), which reveals that the sites of nonmetal dopants (i.e., at O sites or at Ti sites) in TiO$_2$ are determined by the growth condition of doped TiO$_2$ and the dopants' electronegativities. The next section reviews the electronic structure, optical absorption and mechanism of the visible-light photocatalytic activity for nonmetal-doped TiO$_2$. The third section summarizes the origin of the spin-polarization and the magnetic coupling character in C- (N- and B-) doped TiO$_2$.Comment: 21 pages, 24 figures, 3 table

Multivariate Partial Distribution: A New Method of Pricing Group Assets and Analyzing the Risk for Hedging

Based on the Partial Distribution (Feng Dai, 2001), a new model to price an asset (MPA) is given. Going a step further, this paper puts forward the Multivariate Partial Distribution (MPD) for the first time. By use of MPD, we could gain a new kind of model for pricing the group assets (MPGA), in which the competition and cooperation are considered. Based on MPGA, the integrated risk of group assets can be divided to hedging risk and independent risk, and the corresponding models are given. So we could analyze the price risk of group assets in more particular way. The conclusions show that assets are hedged in simple way of one to one can not eliminates completely their market risk in many cases. So there should be an optimal ratio between underlying asset and its derivative in hedging. The approach to determine the optimal ratio in hedging is offered in this paper. By the MPA and MPGA, we also could interpret five of interesting economic propositions in analytic way.multivariate Partial Distribution; pricing assets; group assets; risk analysis; optimal hedging

Multivariate Partial Distribution: A New Method of Pricing Group Assets and Analyzing the Risk for Hedging

Based on the Partial Distribution (Feng Dai, 2001), a new model to price an asset (MPA) is given. Going a step further, this paper puts forward the Multivariate Partial Distribution (MPD) for the first time. By use of MPD, we could gain a new kind of model for pricing the group assets (MPGA), in which the competition and cooperation are considered. Based on MPGA, the integrated risk of group assets can be divided to hedging risk and independent risk, and the corresponding models are given. So we could analyze the price risk of group assets in more particular way. The conclusions show that assets are hedged in simple way of one to one can not eliminates completely their market risk in many cases. So there should be an optimal ratio between underlying asset and its derivative in hedging. The approach to determine the optimal ratio in hedging is offered in this paper. By the MPA and MPGA, we also could interpret five of interesting economic propositions in analytic way.Multivariate Partial Distribution pricing assets group assets risk analysis optimal hedging

Development Power and Its Power Model: The Analytic Approach for Continuous Motivity of Economic Growth

Based on the Partial Distribution [F. Dai, 2001] and the theory of Development Power [F. Dai, 2004], this paper discusses the power model of relation between development power (DP) and productivity. The power model also supports the hypothesis [F. Dai, 2005] that there are three kinds of energy states in economy, i.e. normal state, strong state and super state, and DP is the continuous motivity to economic growth. By the power model of DP, we could interpret in analytic way that the diffusion of DP and the diversifications of economic development also might be occurred after the super state. Finally, the conclusions in this paper are researched in the empirical way, the results indicate the power model is better than the exponential model of DP in many cases, and we could get the inimitable outcomes in describing the macroeconomic process by the power model of DP.Development Power (DP), Partial Distribution, power model, macroeconomic analysis

Discovery of a two-dimensional topological insulator in SiTe

Two-dimensional (2D) topological insulators (TIs), a new state of quantum matter, are promising for achieving the low-power-consuming electronic devices owning to the remarkable robustness of their conducting edge states against backscattering. Currently, the major challenge to further studies and possible applications is the lack of suitable materials, which should be with high feasibility of fabrication and sizeable nontrivial gaps. Here, we demonstrate through first-principles calculations that SiTe 2D crystal is a promising 2D TI with a sizeable nontrivial gap of 0.220 eV. This material is dynamically and thermally stable. Most importantly, it could be easily exfoliated from its three-dimensional superlattice due to the weakly bonded layered structure. Moreover, strain engineering can effectively control its nontrivial gap and even induce a topological phase transition. Our results provide a realistic candidate for experimental explorations and potential applications of 2D TIs

Implementing the CRISPR/Cas9 technology in Eucalyptus hairy roots and functional characterization of auxin-dependent transcription factors involved in wood formation

Les Eucalyptus sont les feuillus les plus plantés au monde pour les nombreuses utilisations industrielles de leurs bois tells que la pâte à papier et la production émergente de biocarburants. L'analyse du génome d'Eucalyptus grandis a conduit à l'identification de nombreux candidats impliqués dans la formation du bois, tells que des médiateurs clés de la signalization de l'auxine (Aux/IAA et Auxin Response Factor (ARF). La caractérisation fonctionnelle de ces gènes candidats a été retardée jusqu'à présent par la difficulté de supprimer leurs fonctions dans un système homologue. Pour pallier à cela, le premier objectif de mon travail a été de mettre au point le puissant outil d'édition de gènes "CRISPR/Cas9" en profitant de la transformation de "hairy roots" transgéniques médiée par A. rhizogenes, récemment développée dans l'équipe. Dans un deuxième temps, mon objectif était d'utiliser cette méthode d'édition de génome pour étudier les rôles potentiels de trois facteurs de transcription dépendant de l'auxine (IAA9A, IAA20 et ARF5) dans la formation du bois d'Eucalyptus. Premièrement, comme preuve de concept pour la mise en oeuvre de la technologie CRISPR/Cas9, nous avons ciblé la Cinnamoyl-CoA réductase1 (CCR1), un gène clé de la biosynthèse de la lignine dont les effets de "down-regulation" sont bien connus. Nous avons également utilisé le gène IAA9A comme cible. Presque toutes les lignées transgéniques ont été éditées, mais les taux et les profils d'édition alléliques variaient considérablement selon le gène ciblé. La plupart des événements d'édition ont généré des protéines tronquées. En utilisant une combinaison de spectroscopie à infrarouge transformée de Fourier (FT-IR) et d'analyse multivariée (PLS-DA), j'ai pu montrer que les lignées éditées pour CCR1, étaient clairement séparées des témoins. Les analyses histochimiques ont confirmé la diminution de la lignification et la présence de vaisseaux écrasés dans les lignées éditées pour CCR1, qui sont des caractéristiques de la déficience de ce gène. Bien que l'efficacité de l'édition puisse être améliorée, la méthode décrite ici est déjà un outil utile pour caractériser fonctionnellement des gènes chez l'Eucalyptus. Dans la deuxième partie de mon travail, j'ai utilisé cette méthode d'édition du génome pour muter deux Aux/IAAs (IAA9A et IAA20) ainsi que ARF5 afin de mieux appréhender le rôle de l'auxine dans la régulation de la formation du bois chez l'Eucalyptus. J'ai généré des "hairy roots" soit pour surexprimer ces gènes, soit pour les muter par CRISPR/Cas9. Malheureusement, toutes les plantes transgéniques surexprimant IAA9A et IAA20 (sous le contrôle du promoteur CaMV35S) sont mortes pendant la période de confinement liée au Covid19 et seules trois lignées CRISPR-IAA20 ont survécu. Par conséquent, je n'ai pu analyser que des plantes transgéniques éditées pour deux candidats. Les lignées IAA9A générées par CRISPR/Cas9 présentaient des taux de knock-out élevés de 92,3% avec 58,3% de mutations bialléliques. En revanche, les lignées ARF5 avaient des taux d'édition assez faibles (43%) et des mutations monoalléliques et/ou chimériques. Dans les lignées éditées pour IAA9A, nous avons observé un développement précoce du xylème et une augmentation du diamètre des vaisseaux du xylème. Enfin, j'ai participé au criblage d'une banque double hybride de xylème d'Eucalyptus (Y2H) pour trouver des partenaires potentiels de IAA9A et IAA20. Pour IAA9A, des candidats prometteurs ont été obtenus tels que Histone Linker (EgH1.3) et CCoAOMT2, connus comme étant impliqués dans la formation du xylème ; pour IAA20, l'interacteur principal est IAA9A, ce qui suggère que IAA20 et IAA9A forment des dimères pour réguler la formation du bois. Nous avons également utilisé la méthode double hybride ciblée pour confirmer les interactions protéine-protéine d'IAA9A et d'IAA20 avec ARF5 ainsi qu'avec d'autres candidats préférentiellement exprimés dans le xylème d'Eucalyptus.Eucalyptus is the most planted hardwood worldwide for many industrial end-uses such as pulp and paper and emerging biofuel production. The analysis of the Eucalyptus grandis genome led to many candidate genes involved in wood formation including key mediators of auxin signaling (Auxin/Indole-3-Acetic Acid (Aux/IAA) and Auxin Response Factor (ARF). The functional characterization of these candidate genes was hampered by the difficulty to general stable transgenic Eucalyptus and to knock out these genes. Taking advantage of rapid and efficient hairy root transformation mediated by A.rhizogenes, recently implemented by our team, the objectives of my work were to implement the powerful CRISPR/Cas9 gene editing tool and to use it to investigate the potential roles of three Eucalyptus auxin-dependent transcription factors (IAA9A, IAA20 and ARF5) in regulating wood formation. First, as a proof-of-concept for implementing CRISPR/Cas9, We targeted Cinnamoyl-CoA Reductase1 (CCR1), a key lignin biosynthetic gene whose down-regulation effects are well described in several plants. Almost all transgenic lines were edited but the allele-editing rates and profiles varied greatly depending on the genes targeted. Most edition events generated truncated proteins. The prevalent edition types were small deletions but large deletions were also observed. By using a combination of Fourier Transformed InfraRed (FT-IR) spectroscopy and multivariate analysis (partial least square analysis (PLS-DA), we showed that the CCR1-edited lines, which were clearly separated from the controls. The most discriminant wave-numbers were attributed to lignin. Histochemical analyses further confirmed the decreased lignification and the presence of collapsed vessels in CCR1-edited lines, which are characteristics of CCR1 deficiency. Although the efficiency of editing could be improved, the method described here is already a useful tool to functionally characterize eucalypts genes. In the second part of my work, we used this genome editing method to knock out two Aux/IAAs (IAA9A and IAA20) and one Auxin Response Factor (ARF5) in order to get more insights into the role of auxin in the regulation of wood formation in Eucalyptus. We generated transgenic Eucalyptus hairy root to overexpress and to knock out these genes. Unfortunately, all the transgenic plants overexpressing IAA9A and IAA20 (under the control of 35S promoter) died during the Covid19 lockdown period and only three IAA20-CRISPR lines survived. Therefore, we could only analyze CRISPR/Cas9 edited transgenic plants for two candidates (IAA9A and ARF5). Editing events were detected either by subcloning and/or webbased tools (DSDecode and ICE synthego). CRISPR/Cas9 generated IAA9A_lines had high knockout rates of 92.3% with 58.3% of biallelic mutations. In contrast, ARF5 lines had quite low editing rates (43%) showing monoallelic and chimera mutations. In IAA9A_edited lines we observed precocious xylem development and increased xylem vessel diameters, while no obvious phenotype was detected in ARF5_edited lines. Finally, we screened a Eucalyptus developing xylem Yeast Two-Hybrid (Y2H) library to find potential partners of IAA9A and IAA20. For IAA9A, we found some potentially promising candidates such as Histone Linker (EgH1.3), CCoAOMT2 previously reported to be involved in xylem formation; for IAA20 the main interactor revealed was IAA9A, suggesting that IAA20 and IAA9A form dimers in developing xylem to regulate wood formation. In addition, we used the yeast two hybrid method to confirm protein-protein interactions of EgrIAA9A and EgrIAA20 with EgrARF5 and other candidates preferentially expressed in Eucalyptus wood-forming tissue