Island Shape Research Articles

Effects of habitat fragmentation on the functional diversity of insects in Thousand Island Lake, China

AbstractDue to habitat fragmentation, the loss of species diversity has been extensively studied. On the contrary, the effects of habitat fragmentation on functional diversity is still poorly understood. In the Thousand Island Lake, we conducted studies of insect functional diversity on a set of 29 isolated islands. We used 10 functional diversity indices from three aspects (functional richness, functional evenness and functional divergence) to respectively describe functional diversity of insects on sample islands.We found the following results: (i) The functional indices selected could reflect the functional diversity of sample islands and it is further proved that in general, three components of functional diversity were independent of each other; (ii) Sample islands could be divided into two categories, island JSD and the remaining islands; (iii) Functional richness increased with island area and shape index, but had no significant correlation with isolation. Likewise, both functional evenness and functional divergence had no significant correlation with island attributes. The conclusion to emphasize from our research is that: (i) habitat fragmentation reduced the biological functional diversity to some extent, further demonstrating the importance of habitat continuity in biodiversity protection; and (ii) for functional diversity protection of insects in a fragmented landscape, an island which has high approximate shape index values of at least hundred hectare magnitude order has a critical promoting effect.

Controlling the supermagnetic response of tetragonal α-FeSi2 nanoislands

We used solid phase (SPE) and reactive deposition (RDE) epitaxy to grow crystallographically identical – but morphologically different – islands. Tetragonal α-FeSi2 islands crystallized pseudomorphically in the α-FeSi2(1 1 2)〈1 1 0〉||Si(1 1 1)〈1 1 0〉 and α-FeSi2(1 1 0)〈1 1 1〉||Si(2 2 0)〈1 1 2〉 orientation relations, with flat (2 × 2)-reconstructed top facets. The SPE-grown islands self-ordered in the form of 1D chains decorating the vicinal Si(1 1 1) step bunch edges along a specific 11¯0 direction. The RDE-grown islands elongated along three equivalent 112¯ directions, and were typically shorter, narrower, and thinner than the SPE-grown ones. In both cases, vast majority of the islands evolved sufficiently close to one another to enable dipolar interactions. Analyzing response to applied magnetic field, we identified areas of the island perimeter rims as the source of uncompensated magnetic moments creating the superspins, lateral island shape anisotropy as the origin of magnetic anisotropy, and periodic 1D ordering of interacting SPE-islands as the origin of superferromagnetic order. In contrast, three-fold orientational domains of the smaller RDE islands showed behavior more consistent with a superspin glass state. The above comparison emphasizes importance of the number of atoms at the island perimeter rims, and the role of dipolar interactions between the islands, for the magnetic behavior of the system.

A Modification in the Shape of the Skin Island of Fasciocautaneous Flaps in the Distal Extremities

Background: Distally based (reversed flow) fasciocautaneousflaps are used for coverage of distal extremity softtissue defects. However, there is a high incidence of venouscongestion that may lead to partial or total flap loss. Variousmodifications for these flap design have been made aimingto improve flap survival.Aim of Work: In this paper, a tongue like extension fromthe skin island was done aiming to improve its versatility anddecrease complication rate especially venous congestion.Patients and Methods: Eight patients (five males andthree females), average age thirty years old. Most cases wherepost traumatic, one case necrotizing fasciitis of heel, one casewith squamous cell cancer of dorsal hand skin. Five patientsunderwent reversed sural flap and three patients underwentradial forearm flap.Results: All cases had viable flaps with good woundhealing. However female patients complained of the scarringlater on. One case of reversed sural flap had minimal distalcongestion that improved later on.Conclusion: Advantage of this modification is that it actsto stabilize the critical vascular pattern of the pedicle duringits axial rotation minimizing the post insetting vascularproblem. It improves the venous drainage through the subdermaland subcutaneous venous plexuses and limits the excesskinking of the fascial pedicle. This tongue of tissue can alsoserve as an extra tissue to be used for coverage in some cases.It also has a superior cosmetic appearance when compared toskin grafting of the pedicle. The use of this modified techniquecan be extended to any island flap that has to pass through atight tunnel to reach the defect.

Brute Force Composition Scanning with a CALPHAD Database to Find Low Temperature Body Centered Cubic High Entropy Alloys.

We used the Thermo-Calc High Entropy Alloy CALPHAD database to determine the stable phases of AlCrMnNbTiV, AlCrMoNbTiV, AlCrFeTiV and AlCrMnMoTi alloys from 800 to 2800 K. The concentrations of elements were varied from 1–49 atom%. A five- or six-dimensional grid is constructed, with stable phases calculated at each grid point. Thermo-Calc was used as a massive parallel tool and three million compositions were calculated, resulting in tens of thousands of compositions for which the alloys formed a single disordered body centered cubic (bcc) phase at 800 K. By filtering out alloy compositions for which a disordered single phase persists down to 800 K, composition ‘islands’ of high entropy alloys are determined in composition space. The sizes and shapes of such islands provide information about which element combinations have good high entropy alloy forming qualities as well as about the role of individual elements within an alloy. In most cases disordered single phases are formed most readily at low temperature when several elements are almost entirely excluded, resulting in essentially ternary alloys. We determined which compositions lie near the centers of the high entropy alloy islands and therefore remain high entropy islands under small composition changes. These island center compositions are predicted to be high entropy alloys with the greatest certainty and make good candidates for experimental verification. The search for high entropy islands can be conducted subject to constraints, e.g., requiring a minimum amount of Al and/or Cr to promote oxidation resistance. Imposing such constraints rapidly diminishes the number of high entropy alloy compositions, in some cases to zero. We find that AlCrMnNbTiV and AlCrMoNbTiV are relatively good high entropy alloy formers, AlCrFeTiV is a poor high entropy alloy former, while AlCrMnMoTi is a poor high entropy alloy former at 800 K but quickly becomes a better high entropy alloy former with increasing temperature.

Valence and Inner Electronic Excitation, Ionization, and Fragmentation of Perfluoropropionic Acid.

The photoexcitation, photoionization, and photofragmentation of gaseous CF3CF2C(O)OH were studied by means of synchrotron radiation in the valence and inner energy regions. Photofragmentation events were detected from 11.7 eV through formation of COH+, C2F4+, and the parent species M+. Because the vertical ionization potential has been reported at 11.94 eV, the starting energy used in this study, 11.7 eV, falls just inside of the tail of the ionization band in the photoelectron spectra. Information from the total ion yield spectra around the C 1s, O 1s, and F 1s ionization potentials allows the energies at which different resonance transitions take place in the molecule to be determined. These transitions have been assigned by comparison with the results of the analysis of similar compounds. In the inner energy region, both kinetic energy release (KER) values and the slope and shape of double coincidence islands obtained from photoelectron-photoion-photoion coincidence (PEPIPICO) spectra allow different photofragmentation mechanisms to be elucidated.

Differential Inhibition during Cu Electrodeposition on Ru: Combined Electrochemical and Real-Time TEM Studies

The time-dependent inhibition of the copper deposition reaction on Ru surfaces was investigated electrochemically at rotating-disc Cu and Ru electrodes in the presence and absence of organic plating additives. The copper deposition rate is high on bare ruthenium. It decreases as the ruthenium surface becomes coated with copper and as the plating additives adsorb and eventually reaches the slow steady-state copper deposition kinetics on copper itself. This differential inhibition effect (DIE) of copper additives during direct electroplating on a foreign substrate (i.e. not copper) is investigated with voltammetry and potentiometry at a rotating Ru disk electrode, and compared with a rotating Cu electrode. We also use simultaneous electrochemical measurements and in situ transmission electron microscopy (TEM) to study nucleation and growth of copper islands electrodeposited on ruthenium electrodes. Combining the in situ TEM and electrochemical measurements allows us to observe the growth of individual islands in real time and establish the effects of additives on island shape and saturation island density.

Interface energy analysis of III–V islands on Si (001) in the Volmer-Weber growth mode

The experimental island shapes of III–V islands grown on silicon (001) in the Volmer-Weber growth mode are analyzed in the frame of the theory of wetting in crystals. A reverse Wulff-Kaishew (or Winterbottom) construction is used in order to access interfacial energy. We apply this approach to AlSb and GaSb islands on (001) Si grown by molecular beam epitaxy and observed by scanning transmission electron microscopy. Experimental ratios between energies of (001), (110), (111)A, and (111)B surfaces are established. Interface energies are then quantitatively estimated for GaSb/Si and AlSb/Si interfaces. The differences in the shape of GaSb and AlSb islands, which are consistently reported in the literature, can be clearly attributed to a higher energy for the GaSb/Si interface compared to the ASb/Si one and not to different adatom diffusion lengths. The difference in interface energies is quantified, and its origin at the microscopic level is discussed.

An ontology and a memory island to give access to digital literature works

AbstractWe have designed an ontology to index a corpus of digital literature works. We have given this ontology the shape of a memory island, a navigable virtual territory where categories are regions and descriptor places, and where archives of these ephemeral works are made accessible.

Mechanical response of an epithelial island subject to uniaxial stretch on a hybrid silicone substrate.

The mechanical response of large multi-cellular collectives to external stretch has remained largely unexplored, despite its relevance to normal function and to external challenges faced by some tissues. Here, we introduced a simple hybrid silicone substrate to enable external stretch while providing a physiologically relevant physical micro-environment for cells. We micropatterned epithelial islands on the substrate using a stencil to allow for a circular island shape without restraining island edges. We then used traction force microscopy to determine the strain energy and the inter-cellular sheet tension within the island as a function of time after stretch. While the strain energy stored in the substrate for unstretched cell islands stayed constant over time, a uniaxial 10% stretch resulted in an abrupt increase, followed by sustained increase in the strain energy of the islands over tens of minutes, indicating slower dynamics than for single cells reported previously. The sheet tension at the island mid-line perpendicular to the stretch direction also more than doubled compared to unstretched islands. Interestingly, the sheet tension at the island mid-line parallel to the stretch direction also reached similar levels over tens of minutes indicating the tendency of the island to homogenize its internal stress. We found that the sheet tension within large epithelial islands depends on its direction relative to that of the stretch initially, but not at longer times. We suggest that the hybrid silicone substrate provides for an accessible substrate for studying the mechanobiology of large epithelial cell islands.

(Invited) Fabrication Technique for Low-Temperature Aqueous Solution-Processed Oxide Thin-Film Transistors

Thin-film transistors (TFTs) prepared using oxide semiconductors have attracted considerable attention for use in driving devices owing to their excellent electrical properties (1). Alternative facile fabrication methods based on solution processing are recognized as advanced oxide TFT fabrication methods (2, 3). Solution-process fabrication is promising technology owing to advantages such as lower processing costs, easier large-area fabrication, and higher throughput compared to conventional vacuum processing. However, it has several limitations that must be mitigated so that the method can be used in practical applications. One such limitation is the processing temperature for the fabrication of solution-processed oxide TFTs. In general, solution-processed oxide TFTs need relatively high-temperature annealing for metal–oxide–metal bond formation and decomposition of the solvents and ligands of metal salts. High-temperature annealing over 400 °C cannot incorporate onto the flexible substrate. Another limitation is that the fabrication process is complex. Although solution processing can be performed using basic equipment such as a coater and annealing equipment, it requires a complicated photolithography process for device integration. A simple fabrication process based on direct patterning procedures is useful for maximizing the advantages of solution processing. In this presentation, we introduce our recent studies on techniques for fabricating low-temperature aqueous solution-processed oxide TFTs, as well as simpler fabrication based on the direct patterning process. We demonstrate the improvement in the characteristics of low-temperature oxide TFTs by applying the hydrogen injection and oxidation (HIO) process (4). From the technical standpoint, decomposing residual species efficiently is of primary importance. We initiated the reduction reaction by hydrogen injection for decomposing the residual spices. The characteristics of the resulting In-Ga-Zn oxide (IGZO)-based TFTs were evaluated by applying the HIO method at low temperatures. The fabrication of IGZO TFTs on film substrate were also demonstrated. For process simplification, we report a direct photoreactive patterning method for fabricating solution-processed IGZO TFTs using a simple aqueous IGZO precursor without any the need for organic-based additives. This is accomplished by photo-oxidation of water molecules based on free radical reactions induced by short-wavelength UV light. In addition, a soft etching step using a dilute organic acid is employed. By combining these processes, a photoreactive patterning system capable of generating uniform island shapes for fabricating solution-processed IGZO TFTs is demonstrated. We demonstrate the advantages of the TFTs fabricated using the direct patterning process by comparing their performance with that of the TFTs fabricated using the conventional photolithography process. K. Nomura, H. Ohta, A. Takagi, T. Kamiya, M. Hirano, and H. Hosono, Nature, 432, 488 (2004). E. Fortunato, P. Barquinha, and R. Martins, Adv Mater, 24, 2945 (2012). S. J. Kim, S. Yoon, and H. J. Kim, Japn J Appl Phys, 53 (2014). M. Miyakawa, M. Nakata, H. Tsuji, Y. Fujisaki, and T. Yamamoto, AIP Advances, 6 (2016).

Formation and morphological evolution of self-similar 3D nanostructures on weakly interacting substrates

Vapor condensation on weakly interacting substrates leads to the formation of three-dimensional (3D) nanoscale islands (i.e., nanostructures). While it is widely accepted that this process is driven by minimization of the total film/substrate surface and interface energy, current film-growth theory cannot fully explain the atomic-scale mechanisms and pathways by which 3D island formation and morphological evolution occurs. Here, we use kinetic Monte Carlo simulations to describe the dynamic evolution of single-island shapes during deposition of Ag on weakly interacting substrates. The results show that 3D island shapes evolve in a self-similar manner, exhibiting a constant height-to-radius aspect ratio, which is a function of the growth temperature. Furthermore, our results reveal the following chain of atomic-scale events that lead to compact 3D island shapes: 3D nuclei are first formed due to facile adatom ascent at single-layer island steps, followed by the development of sidewall facets bounding the islands, which in turn facilitates upward diffusion from the base to the top of the islands. The limiting atomic process which determines the island height, for a given number of deposited atoms, is the temperature-dependent rate at which adatoms cross from sidewall facets to the island top. The overall findings of this study provide insights into the directed growth of metal nanostructures with controlled shapes on weakly interacting substrates, including two-dimensional crystals, for use in catalytic and nanoelectronic applications.

Low-Temperature Growth of Amorphous Water Ice on Ag(111)

Although the wetting of hydrophilic surfaces on the macroscale is a well-known phenomenon, we here develop a microscopic understanding of the more recently discovered complete covering of hydrophobic surfaces by a uniform water layer. For this aim, we deposit D2O on Ag(111) at two different temperatures, 20 and 96 K, and investigate the geometry of the layers at coverages up to four bilayers (BL) by low-temperature scanning tunneling microscopy. In the coverage range up to 0.5 BL, the ice grows in the form of islands that differ largely in size, shape, and density, but surprisingly not in their height. Moreover, the water fills the layer with islands of the same thickness of three to four bilayers at both temperatures. The different island shapes and densities in the coverage range before coalescence are attributed to details in the interaction between water nanoclusters and activated cluster diffusion at the higher growth temperature of 96 K, as visualized in time-lapsed series of scanning tunneling micr...

Effects of habitat fragmentation on the genetic diversity and differentiation of Dendrolimus punctatus (Lepidoptera: Lasiocampidae) in Thousand Island Lake, China, based on mitochondrial COI gene sequences.

Thousand Island Lake (TIL) is a typical fragmented landscape and an ideal model to study ecological effects of fragmentation. Partial fragments of the mitochondrial cytochrome oxidase subunit I gene of 23 island populations of Dendrolimus punctatus in TIL were sequenced, 141 haplotypes being identified. The number of haplotypes increased significantly with the increase in island area and shape index, whereas no significant correlation was detected between three island attributes (area, shape and isolation) and haplotype diversity. However, the correlation with number of haplotypes was no longer significant when the 'outlier' island JSD (the largest island) was not included. Additionally, we found no significant relationship between geographic distance and genetic distance. Geographic isolation did not obstruct the gene flow among D. punctatus populations, which might be because of the high dispersal capacity of this pine moth. Fragmentation resulted in the conversion of large and continuous habitats into isolated, small and insular patches, which was the primary effect on the genetic diversity of D. punctatus in TIL. The conclusion to emphasize from our research is that habitat fragmentation reduced the biological genetic diversity to some extent, further demonstrating the importance of habitat continuity in biodiversity protection.

Effect of the Microstructure and Distribution of the Second Phase on the Stress Corrosion Cracking of Biomedical Mg-Zn-Zr-xSr Alloys.

The stress corrosion cracking (SCC) properties of the bi-directional forged (BDF) Mg-4Zn-0.6Zr-xSr (ZK40-xSr, x = 0, 0.4, 0.8, 1.2, 1.6 wt %) alloys were studied by the slow strain rate tensile (SSRT) testing in modified simulated body fluid (m-SBF). The average grain size of the BDF alloys were approximately two orders of magnitude smaller than those of the as-cast alloys. However, grain refinement increased the hydrogen embrittlement effect, leading to a higher SCC susceptibility in the BDF ZK40-0/0.4Sr alloys. Apart from the grain refinements effect, the forging process also changed the distribution of second phase from the net-like shape along the grain boundary to a uniformly isolated island shape in the BDF alloys. The SCC susceptibility of the BDF ZK40-1.2/1.6Sr alloys were lower than those of the as-cast alloys. The change of distribution of the second phase suppressed the adverse effect of Sr on the SCC susceptibility in high Sr–containing magnesium alloys. The results indicated the stress corrosion behavior of magnesium alloys was related to the average grain size of matrix and the distribution and shape of the second phase.

Thermodynamics and Kinetics of Graphene Growth on Ni(111) and the Origin of Triangular Shaped Graphene Islands

To understand the origin of the triangular shaped graphene, we systematically investigated the thermodynamics and kinetics of graphene growth on Ni(111) surface. It was found that the fcc staking of graphene on the substrate is more energetically favorable than other stacking sequences. Under the near thermoequilibrium condition, a graphene island will present a truncated triangular shape with alternative zigzag (ZZ) and ZZ-Klein edges; its growth is either on the top of the terrace (on-top mode) or embedded into the metal lattice (inlay mode). If the growth process is controlled by kinetics of carbon atom incorporation, the shape of a graphene island will be triangular because of the significant growth rate difference between the ZZ and ZZ-Klein edges. This study reveals the atomic details of graphene growth on Ni(111) surface, and the deep insights into the mechanism of graphene CVD growth may lead to the rational design of experiments for the growth of desired graphene and other 2D materials.

Orientation relationship between ferrite and austenite and its influence on ultrasonic attenuation in cast austenitic stainless steel

Cast austenitic stainless steel (CASS) is widely used in important engineering components, which has a two-phase microstructure, i.e.austenite and ferrite. With slow cooling rate during solidification procedure, the austenite grain is coarse and the morphology of ferrite is complex. Due to the remarkable elasticity anisotropy of austenite, the resulting structural noise makes the recognition of macroscopic defects quite difficult in ultrasonic testing. To improve the signal-to-noise ratio, the ultrasonic testing frequency is generally small, about 0.5-2.0 MHz, and the ultrasonic scattering effect of ferrite is ignored. However, for submillimeter or even smaller defect and damage near the surface, the ultrasonic testing frequency should be increased to achieve a higher resolution. In these cases, how the ferrite influences the ultrasonic wave propagation behavior and the testing result is still not conclusive. Therefore, CASS Z3CN20-09M is studied as an example in this paper. Based on ultrasonic propagation modeling and “in situ” experimental design, the crystal orientation relationship between ferrite and austenite in CASS is studied and the factors influencing the ultrasonic scattering attenuation are clarified. The results would be helpful for clarifying the ultrasonic response mechanism of CASS and critical for the quantitative evaluation of small defects and early-stage damage.<br/>The orientation relationship between ferrite and austenite and its influence on ultrasonic scattering attenuation in CASS are studied. The crystal orientations and their relationships between two phases are characterized by the EBSD technique. A two-dimension anisotropic model is built based on the morphology of ferrite, and the ultrasonic propagation is calculated by the time domain finite difference method. The influences of orientation relationship and morphology on the longitudinal wave attenuation are analyzed and verified by “in-situ” experiments. Results show that ferrite grains with bar or island shape are distributed on the austenite grains. The orientation relationship between ferrite and austenite is mainly Kurdjumov-Sachs relationship, and only a minority of ferrite and austenite satisfy the Nishiyama-Wassermann relationship. Numerical simulation of the ultrasonic propagation under a testing frequency of 15 MHz indicates that the orientation relationships between two phases and ferrite morphologies present collaborative effects on the ultrasonic scattering attenuation, which could not be ignored. The factors influencing the ultrasonic attenuation in <101> austenite grain are quantitatively analyzed. It is found that in single austenite grains of CASS, the inhomogeneity of crystal orientation, the orientation relationship between austenite and ferrite and the ferrite morphology play an important role in determining the total ultrasonic attenuation.<br/>The results would provide supports for clarifying the ultrasonic response mechanism of CASS and developing the quantitative evaluation methods.

An indicative index of physical susceptibility of small islands to coastal erosion induced by climate change: an application to the Pacific islands

ABSTRACTAn objective method is proposed to evaluate the susceptibility of islands to climate change. As used here, susceptibility is an estimate of the potential for physical change of an island coast in response to likely changes in climate–ocean boundary conditions. The evaluation is based on an assumption that the intensity of impact due to climate and ocean processes can be typically related to four physical and quantifiable variables: island rock-type (lithology), island shape (circularity), maximum elevation and area. These four physical variables were used to determine a dimensionless index for each of 1779 islands across 26 countries and 8 island types in the Pacific Ocean. Most islands fell in the high (29%), moderate (23%) and low (23%) susceptibility classes, whilst the remainder were split between the extremes of very high (12%) and very low (13%). Eleven countries had islands with all five levels, while eight had islands with mostly high and very high ratings.The index may be used as a tool for rapid appraisal by international and regional agencies as well as national governments for prioritization of adaptation measures to a changing climate, particularly when combined with climatic and oceanic process variables, together with knowledge of population and infrastructure.

Island shape, size and interface dependency on electronic and magnetic properties of graphene hexagonal-boron nitride (h-BN) in-plane hybrids

We systematically investigate the energetics of ion implantation, stability, electronic, and magnetic properties of graphene/hexagonal boron nitrate (h-BN) in-plane hybrids through first principle calculations. We consider hexagonal and triangular islands in supercells of graphene and h-BN layouts. In the case of triangular islands, both phases mix with each other by either solely CN or CB bonds. We also patterned triangles with predominating CN or CB bonds at their interfaces. The energetics of island implantation is discussed in detail. Formation energies point out that the island implantation could be even exothermic for all hybrids studied in this work. Effects of size and shape of the island, and dominating bonding sort at the island-layout interfaces on the stability, band gap, and magnetic properties of hybrids are studied particularly. The hybrids become more stable with increasing island size. Regardless of the layout, hybrids with hexagonal islands are all non-magnetic and semiconducting. One can thus open a band gap in the semimetallic graphene by mixing it with the h-BN phase. In general, hybrids containing graphene triangles show metallic property and exhibit considerable amount of magnetic moments for possible localized spin utilizations. Total magnetic moment of hybrids with both graphene and h-BN layouts increases with growing triangle island as well. The spin densities of magnetic hybrids are derived from interfaces of the islands and diminish towards their center. We suggest that the increase in stability and magnetic moment depend on the number of atoms at the interfaces rather than the island size.

Micropatterning Different Cell Types with Microarray Amplification of Natural Directional Persistence.

In vivo, different cell types assemble in specific patterns to form functional tissues. Reproducing this process in vitro by designing scaffold materials to direct cells precisely to the right locations at the right time is important for the next generation of biomaterials. Here, using microarray amplification of natural directional persistence (MANDIP), simultaneous assembly of fibroblasts and endothelial cells is demonstrated by directing their long-range migration. Amplification of the directional persistence occurs through morphology-induced polarity and the asymmetric positioning of individual microsized adhesive islands that restrict lamellipodia attachment, and thus migration, to one preset direction. Quantitative analysis of cell migration on different MANDIP designs yields insight to the relative importance of the asymmetric island shapes and their arrangement. The approach enables spatial patterning of different cell types with micrometer-scale precision over large areas for investigation of cell-cell interactions within complex tissue architectures.

Mechanisms and theoretical simulations of the catalytic growth of nanocarbons

Abstract