Nanodot to Nanowire: A strain-driven shape transition in self-organized endotaxial CoSi2 on Si (100)

We report a phenomenon of strain-driven shape transition in the growth of nanoscale self-organized endotaxial CoSi2 islands on Si (100) substrates. Small square shaped islands as small as 15\times15 nm2 have been observed. Islands grow in the square shape following the four fold symmetry of the Si (100) substrate, up to a critical size of 67 \times 67 nm2. A shape transition takes place at this critical size. Larger islands adopt a rectangular shape with ever increasing length and the width decreasing to an asymptotic value of ~25 nm. This produces long wires of nearly constant width.We have observed nanowire islands with aspect ratios as large as ~ 20:1. The long nanowire heterostructures grow partly above (~ 3 nm) the surface, but mostly into (~17 nm) the Si substrate. These self-organized nanostructures behave as nanoscale Schottky diodes. They may be useful in Si-nanofabrication and find potential application in constructing nano devices.Comment: 9 pages, 7 figure

On the Existence of an Equilibrium in Models of Local Public Good Use by Cities to Attract the Creative Class

We analyze a stylized model of competition between two cities that use a local public good (LPG) to attract members of the creative class. The creative class consists of artists and engineers and we study the behavior of a representative artist and an engineer. The level of the LPG in each city is determined by majority voting of the two representative creative class members. If both representative members choose to live in the same city then the LPG provision is the average of the preferred quantities of the two members. In this setting, we perform three tasks. First, we ascertain the preferred quantity of the LPG for the representative artist and the engineer. Second, assuming that the representative artist and the engineer accurately predict the outcome of living in a particular city, we describe a scenario in which there is no equilibrium in our model. Finally, we show that if the representative artist and the engineer treat the LPG provision levels in each city as exogenous then an equilibrium does exist in the model

Faktor snage nanostrukturiranog bizmut telurida određen oblicima

Bismuth telluride is a thermoelectric material with high figure of merit, used for cooling applications at room temperature. To investigate the effect of morphology and grain size on transport parameters, nanostructured bismuth telluride has been synthesized under different reaction conditions and characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. From the measurement of electrical conductivity and thermoelectric power, power factor for different samples has been obtained. The results show that the transport parameters are critically influenced by the morphology and dimension of the samples that in turn depend on the condition of synthesis. The experimentally observed variation of electrical conductivity with the change of dimensionality of the samples from 2D to 0D, which is in line with the theoretical prediction made by other workers, is discussed. There is a variation of the power factor of the samples prepared under different conditions of synthesis.Bizmut telurid je termoelektrična tvar s visokom učinkovitošću koja se rabi za hlađenje na sobnim temperaturama. Radi istraživanja učinka oblika i veličine zrna na transportne parametre, sintetizirali smo nanostrukturirani bizmut telurid u različitim uvjetima i ispitivali rentgenskom difrakcijom, te propusnom i pretražnom elektronskom mikroskopijom. Mjerenjem električne vodljivosti i termoelektrične snage niza uzoraka odredili smo faktore snage. Ishodi analize pokazuju da transportni parametri jako ovise o obliku i veličini uzoraka, koji pak ovise o uvjetima njihove sinteze. Raspravljamo o opaženim promjenama električne vodljivosti ovisnim o dimenzionalnosti uzoraka od 2D do 0D i nalazimo sklad s teorijskim predviđanjima drugih autora. Nalazimo promjene faktora snage uzoraka pripremljenih uz različite uvjete sinteze

Using Local Public Goods to Attract and Retain the Creative Class: A Tale of Two Cities

We study the impact that the provision of a local public good (LPG) by two cities has on their ability to attract and retain members of the creative class. This creative class consists of two types of members known as engineers and artists. Engineers are wealthier than artists and they also value the LPG more. We first focus on each city in isolation. We compute the marginal value and the marginal cost of the LPG and then determine the provision of this LPG when the provision is determined by uniform contributions and majority voting. Next, we allow the creative class members to migrate between the two cities and analyze whether engineers or artists migrate, the equilibrium distribution of the creative class, and the efficiency of the LPG provision. Finally, we consider the situation in each city just before migration and study how much of the LPG is provided when proportional contributions and majority voting determine this provision. A related question we address is whether engineers or artists now have an incentive to migrate and, if yes, we identify who would like to migrate and to which city

Circulating extracellular vesicles and particles derived from adipocytes : the potential role in spreading microRNAs associated with cellular senescence

Aging is associated with adipose tissue dysfunction and is recognized as a risk factor for shortened life span. Considering that in vitro findings have shown the involvement of microRNA in extracellular vesicles and particles (EVPs) on senescence, we hypothesized that circulating EVPs derived from adipocytes can be involved in the aging process via their microRNA cargo. We aimed to determine the microRNA profiles of circulating EVPs derived from adipocytes (FABP4+) from aged and young adult animals and to perform in silico prediction of their downstream signaling effects. Plasma was obtained from Wistar rats (3 and 21 months old), and adipocyte-derived EVPs were isolated using the commercially available kit. Fatty acid-binding protein 4 (FABP4) was used for adipocyte-derived EVPs isolation; microRNA isolation and microarray expression analysis were performed. The analysis revealed 728 miRNAs, 32 were differentially between groups (p < 0.05; fold change ≥ |1.1|), of which 15 miRNAs were upregulated and 17 were downregulated in circulating EVPs from aged animals compared to young adults. A conservative filter was applied, and 18 microRNAs had experimentally validated and highly conserved predicted mRNA targets, with a total of 2,228 mRNAs. Canonical pathways, disease and functions, and upstream regulator analyses were performed using IPA-QIAGEN, allowing a global and interconnected evaluation. IPA categories impacted negatively were cell cycle, cellular development, cellular growth and proliferation, and tissue development, while those impacted positively were “digestive system cancer” and “endocrine gland tumor.” Interestingly, the upregulated miR-15-5p targets several cyclins, such as CCND1 and CCND2, and miR-24-3p seems to target CDK4 (cyclin-dependent kinase 4); then potentially inhibiting their expression, both miRNAs can induce a negative regulation of cell cycle progression. In contrast, silencing of negative cell cycle checkpoint regulators, such as p21 and p16, can be predicted, which can induce impairment in response to genotoxic stressors. In addition, predicted targets, such as SMAD family members, seem to be involved in the positive control of digestive and endocrine tumors. Taken together, this exploratory study indicates that miRNA signature in circulating adipocyte-derived EVPs may be involved with the double-edged sword of cellular senescence, including irreversible proliferation arrest and tissue-dependent cancer, and seems to be suitable for further validation and confirmatory studies