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Effect of electron injection in copper-contacted graphene nanoribbons

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Nano Research 2016年第9期9卷 2735-2746页

作者： Konstantin A.Simonov Nikolay A.vinogradov alexander S.vinogradov alexander v.Generalov Gleb I.Svirskiy Attilio A.Cafolla Nils Martensson Alexei B. Preobrajenski Department of Physics and Astronomy Uppsala UniversityUppsala Box 51675120Sweden MAX Ⅳ Laboratory Lund UniversityLund Box 11822100Sweden v.A.Fock Institute of Physics St.Petersburg State UniversitySt.Petersburg 198504Russia School of Physical Sciences Dublin City UniversityDublin 9Ireland

For practical electronic device applications of graphene nanoribbons (GNRs), it is essential to have abrupt and well-defined contacts between the ribbon and the adjacent metal lead. By analogy with graphene, these contacts can induce electron or hole doping, which may significantly affect the I/v characteristics of the device. Cu is among the most popular metals of choice for contact materials. In this study, we investigate the effect of in situ intercalation of Cu on the electronic structure of atomically precise, spatially aligned armchair GNRs of width N = 7 (7-AGNRs) fabricated via a bottom-up method on the Au(788) surface. Scanning tunneling microscopy data reveal that the complete intercalation of about one monolayer of Cu under 7-AGNRs can be facilitated by gentle annealing of the sample at 80 °C. Angle-resolved photoemission spectroscopy (ARPES) data clearly reflect the one-dimensional character of the 7-AGNR band dispersion before and after intercalation. Moreover, ARPES and core-level photoemission results show that intercalation of Cu leads to significant electron injection into the nanoribbons, which causes a pronounced downshift of the valence and conduction bands of the GNR with respect to the Fermi energy (ΔE ~ 0.5 ev). As demonstrated by ARPES and X-ray absorption spectroscopy measurements, the effect of Cu intercalation is restricted to n-doping only, without considerable modification of the band structure of the GNRs. Post-annealing of the 7-AGNRs/Cu/Au(788) system at 200 °C activates the diffusion of Cu into Au and the formation of a Cu-rich surface Au layer. Alloying of intercalated Cu leads to the recovery of the initial position of GNR-related bands with respect to the Fermi energy (E F), thus, proving the tunability of the induced n-doping.

关键词： graphene nanoribbons bottom-up method copper intercalation charge injection angle-resolved photoemission spectroscopy (ARPES) scanning tunneling microscopy

Multiscale wood micromechanics and size effects study via nanoindentation

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Journal of Bioresources and Bioproducts 2023年第3期8卷 246-264页

作者： Yuri I.Golovin alexander A.Gusev Dmitry Yu.Golovin Sergey M.Matveev alexander I.Tyrin alexander A.Samodurov viktor v.Korenkov Inna A.vasyukova Maria A.Yunack Institute“Nanotechnology and Nanomaterials” G.R.Derzhavin Tambov State University392000 TambovRussia Department of Chemical Enzymology School of ChemistryLomonosov Moscow State University119991 MoscowRussia Research and Educational Center«Sustainable Development of the Forest Complex» Voronezh State Forestry University Named after G.F.Morozov394087 VoronezhRussia Department of Functional Nanosystems and High-Temperature Materials National University of Science and Technology“MISIS”119991 MoscowRussia

Wood as a material is a natural composite with a complex hierarchically arranged *** scale levels of wood structure contribute to its macroscopic mechanical *** nature of such characteristics and deformation modes differs radically at different scale *** macroscopic properties are well studied,and the relevant information can be easily found in the ***,the knowledge of the deformation mechanisms at the mesoscopic level corresponding to the cellular structure of early and late wood layers of annual growth rings is *** hinders building the comprehensive multiscale model of how wood mechanical properties are *** paper described the results of scanning of mechanical properties of softwood and hardwood samples,such as common pine,small-leaf lime,and pedunculate oak,by means of nanoindentation(NI).The NI technique allows varying the size of deformed region within a wide range by altering maximal load(P max)applied to the indenter so that one can re-peatedly and non-destructively test wood structural components at different scale levels on the same sample without changing the technique or *** was discovered that the effective microhardness(H eff)and Young’s modulus(E eff)decreased manifold with P max growing from 0.2 to 2000 *** drop in H effwas observed when the locally deformed region grew,and re-sulting from P max increase generally follows the rule similar to the Hall-Petch relation for yield stress,strength,and hardness initially established for metals and alloys,though obviously in those cases the underlying internal mechanisms are quite *** nature and micromechanisms of such size effect(SE)in wood revealed using NI were discussed in this *** P maxvich indenter was much smaller than the cell wall ***,in this case,NI measured the internal mechanical properties of the cell wall material as long as free boundaries impact

关键词： Nano/microhardness Scanning nanoindentation Annual growth ring Early and late wood Dendrochronology

Origin of the neuro-sensory system: new and expected insights from sponges

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Integrative Zoology 2009年第3期4卷 294-308页

作者： EMMANUELLE RENARD Jean vACELET Eve GAZAvE Pascal LAPéBIE Carole BORCHIELLINI alexander v.ERESKOvSKY Centre d’océanologie de Marseille CNRS–Aix-Marseille UniversitéMarseilleFrance Department of Embryology Saint-Petersburg State UniversitySt.PetersburgRussia

The capacity of all cells to respond to stimuli implies the conduction of information at least over short *** multicellular organisms,more complex systems of integration and coordination of activities are *** most animals,the processing of information is performed by a nervous *** the most basal taxa,sponges are nerveless so that it is traditionally assumed that the integrated neuro-sensory system originated only once in Eumetazoa,a hypothesis not in agreement with some recent phylogenomic *** aim of this review is to show that recent data on sponges might provide clues for understanding the origin of this complex ***,sponges are able to react to external stimuli,and some of them display spontaneous movement *** coordinated behaviors involve nervous system-like mechanisms,such as action potentials and/or ***,genomic analyses show that sponges possess genes orthologous to those involved in the patterning or function-ing of the neuro-sensory system in ***,some of these genes are expressed in specific cells(flask cells,choanocytes).Together with ultrastructural data,this gives rise to challenging hypotheses concerning cell types that might play neuro-sensory-like roles in sponges.

关键词： animal evolution choanocyte flask cells nervous system Porifera signal transduction.

Cluster Analysis of the Roma-BZCAT Blazars

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Research in Astronomy and Astrophysics 2024年第5期24卷 117-139页

作者： Dmitry O.Kudryavtsev Yulia v.Sotnikova vladislav A.Stolyarov Timur v.Mufakharov valery v.vlasyuk Margarita L.Khabibullina alexander G.Mikhailov Yulia v.Cherepkova Special Astrophysical Observatory of the Russian Academy of Sciences Nizhny Arkhyz 369167Russia Astrophysics Group Cavendish LaboratoryUniversity of CambridgeCambridge CB3 OHEUK Kazan Federal University 18 Kremlyovskaya StKazan 420008Russia

Based on the collected multiwavelength data, namely in the radio(NvSS, FIRST, RATAN-600), IR(WISE),optical(Pan-STARRS), Uv(GALEX), and X-ray(ROSAT, Swift-XRT) ranges, we have performed a cluster analysis for the blazars of the Roma-BZCAT catalog. Using two machine learning methods, namely a combination of PCA with k-means clustering and Kohonen's self-organizing maps(SOMs), we have constructed an independent classification of the blazars(five classes) and compared the classes with the known Roma-BZCAT classification(FSRQs, BL Lacs, galaxy-dominated BL Lacs, and blazars of an uncertain type) as well as with the high synchrotron peaked(HSP) blazars from the 3HSP catalog and blazars from the TevCat catalog. The obtained groups demonstrate concordance with the BL Lac/FSRQ classification along with a continuous character of the change in the properties. The group of HSP blazars stands out against the overall distribution. We examine the characteristics of the five groups and demonstrate distinctions in their spectral energy distribution shapes. The effectiveness of the clustering technique for objective analysis of multiparametric arrays of experimental data is demonstrated.

关键词： methods data analysis-galaxies active-(galaxies:)BL Lacertae objects general

Ruthenium-mediated assembly and enhanced stability of heterometallic polystannides[Ru_(2)Sn_(19)]^(4−)and[Ru_(2)Sn_(20)]^(6−)

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Nano Research 2022年第6期15卷 5705-5711页

作者： Wei-Xing Chen Nikolay v.Tkachenko Alvaro Muñoz-Castro alexander I.Boldyrev Zhong-Ming Sun State Key Laboratory of Elemento-Organic Chemistry Tianjin Key Lab of Rare Earth Materials and ApplicationsSchool of Materials Science and EngineeringNankai UniversityTianjin 300350China Department of Chemistry and Biochemistry Utah State University0300 Old Main HillLoganUT 84322-0300USA Grupo de Química Inorgánicay Materiales Moleculares Facultad de IngenieriaUniversidad Autonoma de ChileEl Llano SubercaseauxSantiago 2801Chile

In this work,we report the synthesis and characterization of two novel Ru-containing Zintl clusters:[Sn_(19){Ru(COD)(en)}_(2)]^(4−)and[Sn_(20){Ru(COD)}_(2)]^(6−).The synthesized compounds not only expand the family of Ru-Sn cluster systems but also shed light on the structure of heterometallic complexes in a previously unknown range of tin *** single-crystal X-ray diffraction(XRD)analysis reveals the dimeric nature of the *** different assembly patterns of the formal[Sn(η^(3)-Sn_(9))]monomer were observed:the dimerization through the vertex fusion process and the direct dimerization through the formation of 2c–2e Sn–Snσ*** both clusters,the density functional theory calculations reveal the locallyσ-aromatic nature of the[Sn(η^(3)-Sn_(9))]monomer resulting in two independent magnetic shielding *** believe that our findings will help the community to further explore the fascinating chemistry of polystannide clusters.

关键词： heterometallic clusters aromaticity polystannide ruthenium Zintl anion

Increased paracellular permeability of tumor-adjacent areas in 1,2-dimethylhydrazine-induced colon carcinogenesis in rats

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Cancer Biology & Medicine 2018年第3期15卷 251-259页

作者： viktoria v.Bekusova Evgeny L.Falchuk Larisa S.Okorokova Natalia M.Kruglova alexander D.Nozdrachev alexander G.Markov Department of Physiology St.Petersburg State University I.P.Pavlov Institute of Physiology Russian Academy of Sciences

Objective: The morphology and functions of the proximal and distal large intestine are not the same. The incidence of colorectal cancer in these regions is also different, as tumors more often appear in the descending colon than in the ascending *** bowel disease and colorectal cancer can increase transepithelial permeability, which is a sign of reduced intestinal barrier function. However, there is not enough evidence to establish a connection between the difference in colorectal cancer incidence in the proximal and distal colon and intestinal permeability or the effects of carcinogenesis on the barrier properties in various areas of the colon. The aim of the study was to assess the permeability of different segments of the large intestine according to a developed mapping methodology in healthy rats and rats with 1,2-dimethylhydrazine(DMH)-induced colon ***: The short circuit current, the transepithelial electrical resistance and the paracellular permeability to fluorescein of large intestine wall of male Wistar rats were examined in the Ussing chambers. The optical density of the solution from the serosa side to assess the concentration of the diffused fluorescein from mucosa to serosa was analyzed by spectrophotometry. The morphometric and histological studies were performed by optical ***: Rats with DMH-induced colon adenocarcinomas showed elevated transepithelial electrical resistance in the areas of neoplasm development. In contrast, there was no change in the electrophysiological properties of tumor adjacent areas, however,the paracellular permeability of these areas to fluorescein was increased compared to the control rats and was characterized by sharply reduced barrier ***: The barrier properties of the colon vary depending on tumor location. The tumors were less permeable than the intact intestinal wall and probably have a negative influence on tumor-adjacent tissues by disrupting their bar

关键词： Rat 1,2-dimethylhydrazine colorectal cancer Ussing chamber short circuit current transepithelial electrical resistance intestinal permeability

Multilayers with high-reflectivity at 19.5 nm and low-reflectivity at 30.4 nm

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Chinese Optics Letters 2013年第13期11卷 154-157页

作者：蒋励朱京涛张众王占山 Michael Trubetskov alexander v. Tikhonravov Department Institute of Precision Optical Engineering Department of Physics Tongji University Shanghai 200092 China Lomonosov Moscow State University Russia

The multilayer （ML） mirror with high-reflectivity （HR） at a specific emission line of 19.5 nm （Fe line） and low-reflectivity （LR） at 30.4 nm （He line） is needed to be designed and fabricated for observing the image of sun. Based on a variety of optimizations utilized different structures, the design is performed and the final results demonstrate that the reflectivity at 30.4 nm does not achieve minimum value when the reflectivity at 19.5 nm reaches the maximum value. The tradeoff should be done between the HR at 19.5 nm and LR at 30.4 nm. One optimized mirror is fabricated by direct current magnetron sputtering and characterized by grazing-incident X-ray diffraction （XRD） and synchrotron radiation （SR）. The experimental results demonstrate that the ML achieves the reflectivity of 33.3% at 19.5 nm and of 9.6× 10-4 at 30.4 nm at the incident angle of 13°.

关键词： Reflection

Synthesis and Structure of Binary Copper/Silver-Arsenic Clusters Derived from Zintl Ion As_(7)^(3-)

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Chinese Journal of Chemistry 2022年第1期40卷 65-70页

作者： Wei-Qiang Zhang Nikolay v.Tkachenko Lei Qiao alexander I.Boldyrev Zhong-Ming Sun State Key Laboratory of Elemento-Organic Chemistry Tianjin Key Lab for Rare Earth Materials and ApplicationsSchool of Materials Science and EngineeringNankai UniversityTianjin 300350China Department of Chemistry and Biochemistry Utah State University 0300 Old Main HillLoganUT 84322-0300USA

Polyarsenides containing coinage metals,[As_(7)Cu(PPh_(3))]^(2-)(1)and[M_(2)As_(14)]^(4-)(M=Cu,2;Ag,3),were synthesized by reactions of the nominal composition K_(3)As_(7) with Group 11 metal *** possible intermediate,cluster 1,was isolated from the solution phase through subtle changes in reaction conditions in the formation process of complex ***,we establish the pathway of the bimetallic bridged clusters[Cu_(2)As_(14)]^(4-)by the oxidation of the[As_(7)Cu(PPh_(3))]^(2-).Quantum chemical calculations reveal the presence of metallophilic interaction in clusters 2 and 3.

关键词： Polyarsenide cluster Reaction mechanism Zintl ions Covalently bound Metallophilic interaction

NMR chemical shifts of carbon atoms and characteristic shift ranges in the oil sample

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Petroleum Research 2022年第2期7卷 269-274页

作者： Ilfat Z.Rakhmatullin Sergej v.Efimov alexander v.Klochkov Oleg I.Gnezdilov Mikhail A.varfolomeev vladimir v.Klochkov Kazan Federal University 18 Kremlevskaya St.Kazan420008Russian Federation

Application of high resolution^(13)C nuclear magnetic resonance(NMR)spectroscopy to characterize crude oil was *** chemical shifts of^(13)C NMR functional groups that determine the composition of the oil sample were *** fractions of primary,secondary,quaternary,tertiary,aromatic groups,aromatic factor and average hydrocarbon chain length of aliphatic hydrocarbons of the oil sample according to^(13)C NMR spectra were *** description of the^(13)C NMR spectra of the oil sample using a single consideration of three NMR spectra:^(13)C,^(13)C Attached Proton Test(APT),^(13)C with Gated Decoupling(GD)was *** different contribution of the studied oil sample in the aliphatic(10e75 ppm)and aromatic(115e165 ppm)areas of the^(13)C NMR spectra was *** presence of all major hydrocarbon components in the studied oil sample was established on the quantitative level,the aromaticity factor and the mean length of the hydrocarbon chain were *** fractions of aromatic molecules and functional groups constituting oil hydrocarbons were *** this work we demonstrate that the attached proton test and gated decoupling^(13)C NMR spectroscopy can afford all information to complete the chemical shift assignment of an oil sample,especially for determination of long range 1He^(13)C coupling constants and^(13)C multiplicity.

关键词： ^(13)C NMR spectroscopy Crude oil Oil fraction Functional group Qualitative analysis Quantitative composition Aromaticity Attached proton test Gated decoupling