bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth, Doping, Device Development and Characterization of CVD Beta-SiC Epilayers on Si(100) and Alpha-SiC(0001)
Authors: Kong H. , Kim H. J. , Edmond J. A. , Palmour J. W. , Ryu J. , Carter C. H. , Glass J. T. , Davis R. F.
Published: March 2011

Monocrystalline β-SiC films have been chemically vapor deposited on Si(100) and c-SiC(0001) at 1660K-1823K and 0.1 MPa using SiH4 and C2H4 carried in H2. Films grown directly on Si(100) contained substantial concentrations of dislocations, stacking faults and antiphase boundaries (APB); those on α-SiC(0001) contained double positioning boundaries. Both the APBs and the double positioning boundaries were eliminated by using off-axis orientations of the respective substrates. Films produced on Si(100) have also been doped during growth and via ion implantation with B or Al (p-type) or P or N (n-type) at LN, room and elevated temperatures. Results from the former procedure showed the ionized dopant/total dopant concentration ratios for N, P, B and Al to be 0.1, 0.2, 0.002 and 0.01, respectively. The solubility limits of N, P and B at 1660K were determined to be ∼ 2E20, 1E18 and 8E18 cm−3, respectively; that of Al exceeds 2E19 cm−3. High temperature ion implantation coupled with dynamic and post annealing resulted in a markedly reduced defect concentration relative to that observed in similar research at the lower temperatures. Schottky diodes, p-n junctions, and MOSFET devices have been fabricated. The p-n junctions have the characteristics of insulators containing free carriers and deep level traps. The MOSFETs show very good I-V characteristics up to 673K, but have not been optimized.
Residual Donors in P-SiC Films
Authors: Carlos W. E. , Moorea W. J. , Siebenmann P. G. , Freitas J. A. , Kaplan R. , Bishop S. G. , Nordquist P. E. R. , Kong M. , Davis R. F.
Published: March 2011

Electron Spin Resonance (ESR), temperature dependent Hall effect measurements and photoluminesence (PL) are used to examine the assumption that the residual donor in β-SiC films is nitrogen. At low temperatures the ESR has a three line isotropic spectrum which is characteristic of a central hyperfine interaction with nitrogen. The temperature dependence of the intensity of the nitrogen ESR signal correlates with the concentration of un-ionized donors measured by the Hall effect. Donor-Acceptor pair PL spectra are used to establish that the binding energy of the dominant donor in the films is the same as the nitrogen donor observed in Lely-grown samples. Neither PL nor ESR provide any evidence for the presence of a shallower donor.
Thermally Activated Reactions of Titanium Thin Films with (100) 3C-SiC Substrates
Authors: Bellina J. J. , Zeller M. V.
Published: March 2011

The reaction of thin Ti films deposited, in situ, onto (100) 3C-SiC has been studied by Auger Electron Spectroscopy, and Low Energy Electron Diffraction. The effects of reaction temperature and SiC surface condition were investigated as part of a program to obtain a high temperature electrical contact for this wide band gap semiconductor.

The results indicate that the interface reaction is dominated by the formation of TiC in SiC, and the liberation of Si which diffuses to the surface. The amount of liberated Si depended on the relative amounts of free surface C and of deposited Ti. In the presence of excess carbon, the reaction of Ti with SiC was suppressed and a (TiC + C) surface layer formed which was stable after 500 hours at 800°C.
Effects of the Subsequent Ion Irradiation on the Formation Process of β-SiC from Si-C Mixtures Fabricated on Si by Ion Implantation
Authors: Kimura Tadamasa , Yamaguchi Hiroyuki , Yugo Shigemi , Adachi Yoshio
Published: March 2011

The β-SiC formation process through post-implantation annealing of Si-C mixtures fabricated on Si by C-ion implantation at room temperature is studied by means of infrared absorption spectroscopy. It is shown that the formation of B-SiC from the Si-C mixtures is greatly enhanced by the subsequent irradiation of other energetic ions prior to the thermal annealing. The continuous amorphization of the Si-C mixed layers is considered to be the dominant cause for the enhancement of the B-SiC formation. The activation energy of the β-SiC formation process which is 5.3 eV without irradiation is reduced to 4.0 eV by the irradiation of 150 keV, 1 × 1017/cm2 Ar ions.
Sputtered Fitas of Amorphous Hydrogenated Silicon Carbide
Authors: Rizk Richard B. , Kaloyeros Alain E. , Williams Wendell S. , Finnegan Nancy , Kozlowski Carol
Published: March 2011

The field of amorphous hydrogenated silicon-carbon alloys and thin films has witnessed, since the pioneering work of Anderson and Spear [1], rapid development and has attracted scientific attention and technological interest [2,3]. However, relatively little information is known [4] about the physical mechanisms that govern the inclusion of C and H in the silicon matrix, the nature of the chemical bonds involved, and the structural changes that result in the amorphous phase. Clearly, further fundamental studies are needed to achieve complete understanding of such amorphous systems with variable disorder.
Icosahedral Boron-Rich Solids as Refractory Semiconductors
Authors: Emin David
Published: March 2011

Icosahedral boron-rich solids are refractory materials composed of twelve-atom boron-rich icosahedral units with strong intericosahedral linkages. These distinctive structures admit unusual electronic and thermal transport properties. Here the distinctive (three-center) bonding which underlies these materials is first described. Then it is shown how insulators, semiconductors and highly degenerate (metal-like) materials emerge from the same basic structure with appropriate substitutions.

The electronic transport of the boron carbides is then addressed. The boron carbides are degenerate p-type semiconductors in which the charge carriers are diamagnetically aligned pairs of electrons which hop between icosahedra. Uniquely, this thermally activated hopping conductivity increases with increasing hydrostatic pressure. However, the Seebeck coefficient (thermoelectric power) is uncharacteristic of a degenerate semiconductor. Namely, the Seebeck coefficient is typically both large and an increasing function of temperature. In addition, despite the hardness and refractory character of these materials, their thermal conductivities can be surprisingly low with a glass-like temperature dependence. These features are manifestations of the distinctive structure and bonding of these solids. In fact, this novel mix of properties makes the boron carbides exceptionally good very-high-temperature p-type thermoelectric materials.

Icosahedral boron-rich solids have additional potential as high temperature semiconductors. In particular, the wide-gap icosahedral boronrich pnictides, B12P2 and B12As2, may be doped to form wide-gap refractory semiconductors. For example, replacement of the group V element with either a group VI or a group IV element is expected to yield n-type and ptype material, respectively.
Lanthanide Refractory Semiconductors Based on the Th3P4 Structure
Authors: Gschneidner K. A. , Nakahara J. F. , Beaudry B. J. , Takeshita T. , Laboratory Ames
Published: March 2011

The phase relationships and the important structural, electrical and thermal properties of the R3X4-R2X3 (where R = lanthanides and X = S, Se and Te) phases having the Th3P4 -type structure are reviewed. The room temperature electrical resistivity and Seebeck coefficient of these materials are independent of R and only slightly dependent on X, but critically dependent on the X:R ratio. The long term stability of these phases is also reviewed. Although these materials have good thermoelectric properties there are some problems which need to be solved before these phases can be utilized in thermoelectric devices. These problems include long term stability, higher than desirable thermal conductivities, and low electron mobilities.
Synthesis, Magnetic, Electrical and Mössbauer Investigations on Complex Semiconductors
Authors: Steinfink Hugo , Swinnea John Steven
Published: March 2011

The system Ba-Fe-S contains a phase Ba1+xFe2S4 whose structure consists of infinite chains of FeS4 edge sharing tetrahedra with Fe-Fe distances of 2.7Å. The chains are 6 Å apart and Ba2+ fills the space between the chains. Each value of x designates a distinct phase and such structures have been labeled “infinitely adaptive.” The Ba1+xFe2S4 compounds are anisotropic semiconductors. The room temperature electrical conductivity for the x = 0 and x = 0.086 phases changes by nearly 6 orders of magnitude as increasing x populates the conduction band. The preparation of these materials requires very careful control of sulfur vapor pressure in closed ampules at elevated temperatures. A similar effect is observed in rare earth sulfides with the Th3P4 structure. Intrinsic La2S3 and BaLa2S4 are predicted to be high resistivity semiconductors. As the composition changes to a stoichiometry such as Ba0.8La2.2S4 the behavior becomes semi-metallic. Control of the sulfur vapor pressure will be a critical parameter for designing physical parameters into these compounds.
Role of Oxygen in Rare Earth Chalcogenide Semiconductors
Authors: Vaughan Cheryl M. , White William B.
Published: March 2011

Oxygen uptake by the rare earth chalcogenides takes place through a series of ordered compounds. At high oxygen concentrations the distinct and nearly stoichiometric oxychalcogenides, Ln202X (X = S, Se, Te) appear. For the chalcogenides of the larger rare earths there appears an ordered oxygen-containing beta structure, Ln10X14OxX1-x (X = S, Se). The vibrational spectrum of the trigonal oxysulfide structure contains four infrared and four Raman bands (2 A2u + 2 Eu + 2 Alg + 2 Eg). Band wavenumbers across the La to Lu series vary linearly with unit cell volume. The Raman bands are sharp indicating a high degree of order in the intermediate compounds. The Raman bands of the beta structure are remarkably sharp indicating that this compound also has a highly ordered structure. Known data plus synthesis data are combined to form not-impossible phase diagrams for the larger rare earth sulfide systems. The effect of oxygen in both series of compounds is to produce small wavenumber shifts rather than high wavenumber oxygen impurity bands.
Atomic Interactions in a Boron-Rich Carbon-Containing Icosahedron: Para-Carborane
Authors: Beckel C. L. , Obarski G. E. , Fuka M. Z. , Fritts J. D.
Published: March 2011

Boron carbides contain carbon atoms as substituents for boron in icosahedra. The B-C interaction is different in icosahedra from that in other geometric forms. Para-carborane, P-C2B10H12, offers an excellent system for the study of structure and interactions in boron-rich, carbon-containing icosahedra; its structure is well-characterized experimentally, and the infrared and Raman spectra have been observed and are relatively simple. Here we present an analysis of p-carborane by classical force field methods supplemented by quantum mechanical calculations. Complexity in the model cluster is introduced step-by-step beginning with B12 (Ih symmetry). The principal interaction constants extracted through interpretation of p-C2B10H12 spectra are kCB −2.0 × 105 dyne/cm, kBB (intrapentagon) −1.3 × 105 dyne/cm, and kBB (interpentagon) −1.55 × 105 dyne/cm.
Temperature Measurements in Atmospheric Spraying Plasmas Jets : Gas and Particles in Flight
Authors: Fauchais P. , Coudert J. F. , Vardelle M. , Vardelle A.
Published: March 2011

Spectroscopic temperature measurements of spraying plasma jets (produced by D.C. arcs) are studied (equilibrium conditions, influence of the surrounding environment of plasma jets at 1 atm). For solid particles in flight in these jets are presented the measurement methods of surface temperature, particle vapors densities and excitation temperatures. The “limitation of these measurements are discussed and examples are given.
In-Situ Monitoring of Electrical Parameters for Dry Etching
Authors: F J. Ignacio Ulacia , McVittie James P.
Published: March 2011

In this paper, external electrical measurements and a circuit model are used to obtain indirectly the plasma potential, electron density, ion current density, and sheath thickness. In a revised and extended circuit model, each element describes a current-transport mechanism. Each mechanism is described by an analytical expression in terms of previously specified plasma parameters. The model is applicable in capacitive discharges with equal-area electrodes, and it can be expanded to consider other systems. To verify its applicability, electrical measurements of voltage, current and phase angle in an SF6 : O2 discharge are used to calculate the plasma impedance. Electrical plasma measurements yield time-averaged values for the impedance; the values obtained for each device reflect this dependency. After the calculation of each electrical device, SPICE 3.7a simulations separated the individual contribution of current transport by each mechanisms and validated the assumptions. The plasma parameters obtained by this technique agree well with a Langmuir-probe measurement, solutions of the Boltzmann transport equation, and data published in the literature.
Theoretical Prediction of the Effect of Coil Configuration on Gas Mixing in an Inductively Coupled Plasma Torch
Authors: Mckelliget John W. , El-Kaddah Nagy
Published: March 2011

A mathematical model for the analysis and design of inductively coupled plasma torches Is presented. The model is based upon a solution of the electromagnetic vector potential equation and is capable of predicting the two-dimensional velocity, temperature, and electromagnetic fields as well as the reaction kinetics inside the torch for any axi-symmetric coil configuration. The model is used to study the effect of coil geometry on the thermal decomposition of silicon tetrachloride to silicon. The coil geometry Is found to affect both the temperature field and the flow field and to have a significant effect on the reaction kinetics in the torch. It is demonstrated that through fundamental changes in the coil design It is possible to control the location of the reaction zone and to prevent silicon deposition on the wall of the reactor.
Growth and Characterization of Epitaxial GaAs Deposited by Plasma-Enhanced Metal-Organic Chemical Vapor Deposition
Authors: Huelsman A. D. , Yoon E. , Reif R.
Published: March 2011

Epitaxial GaAs films have been deposited using a Plasma-Enhanced Metal Organic Chemical Vapor Deposition (PE-MOCVD) technique. This technique uses an RF discharge to dissociate arsine and hydrogen upstream from the substrate. The plasma increases the partial pressure of arsenic above the substrate and improves the growth and quality of GaAs films grown at low teyperature and with low arsine flow rates. We have used photoluminescence, Hall measurements, dislocation etches, and transmission electron microscopy (TEM) to study the properties of films grown with and without plasma. enhancement under a variety of reactor conditions. Specular epitaxial layers of n-GaAs were grown with and without plastua at, very low pressures (2 – 3 Torr) on semiinsulating GaAs substrates. Layers grown both with and without the plasma showed good mobility and photoluminescence at deposition temperatures of 650°C. At lower deposition temperatures the films deposited with the plasma were better than those deposited without the plasma. A KOH-NaOH eutectic etch revealed a better structural quality in films deposited with plasma at low arsine partial pressure.
A Study of Titanium Silicide Polycide Etching
Authors: Bobbio S. M. , Ho Y. S. , Lopez T.
Published: March 2011

The reactive ion etching of polycide films (TiSi2 over polysilicon) is discussed. Experimental conditions which lead to anisotropy and the identification of certain contamination problems as well as their solution are presented.
X-Ray Photoemission Study of Silicon Nitride-GaAs Interfaces in Relation with GaAs Mesfet Passivation
Authors: Alnot Patrick , Olivier J. , Wyczisk F. , Peray J. F. , Joubart R.
Published: March 2011

We have studied the influence of different GaAs surface treatments on the chemical composition and electrical behavior of the Si 3 N4 -GaAs interface, where Si 3 N4 was plasma enhanced chemical vapor deposited (PECVD) onto the treated GaAs(100) substrate. The chemistry of the resulting interface has been studied by X-ray photoelectron spectroscopy (XPS). It has been demonstrated that the chemical composition of the Si 3 N4-GaAs interface is drastically dependent on GaAs surface pretreatment and r.f. plasma excitation frequency. Output-input powers characteristics have been measured on chemically treated planar MESFET after Si3N4. passivation.
Measurement of Plasma Etch-Induced Damage to Silicon Beneath Si0 2 Layer: Effective Range of Plasma Etch Damage Through Si0 2
Authors: Smith W. Lee , Connick I-Wen Huang
Published: March 2011

The ability to pattern VLSI wafers by plasma etching through SiO2 without causing structural damage and chemical contamination to the underlying silicon material is today highly desired. Examples are the plasma etching of metal/silicon contact holes and the fabrication of charge injection windows for EEPROM devices. Damage to underlying silicon, which may adversely affect contact resistance, oxide breakdown or charge retention properties, occurs as the oxide is reduced in thickness below a certain penetration depth (Dox). Dox is the effective projected range of damage-producing particles in Si0 2, and is a function of the distributions of energy, mass, etc., of the plasma constituents. In this paper we describe the use of thermal wave modulated reflectance in conjunction with a simple tapered-oxide film structure to measure the depth of penetration of etch-induced damage through SiO 2. Results on the dependence of the penetration depth on RIE self-bias voltage and other observations of etch-induced surface modifications are reported.
The Mathematical Modelling of Transport Phenomena in Non-Transferred Plasma Systems: Accomplishments and Unresolved Problems
Authors: Dilawari A. H. , Szekely J.
Published: March 2011

An overview is presented of transport phenomena in non-transferred plasma arc systems. It has been shown that while the modelling of these systems involves the standard application of computational fluid mechanics techniques, numerous pitfalls may be encountered in practice. A detailed discussion of these is presented, with emphasis on the torch inlet conditions, the effect of swirl, the temperature dependence of the system properties and the laminar-turbulent transition in the system. A critical comparison is presented with experimental measurements, and the necessary future work is also outlined.
The Effects of Modulation on an RF Discharge in Silane and on the Deposited a-Si:H
Authors: Overzet L. J. , Verdeyen J. T. , Roth R. M. , Carasco F. F.
Published: March 2011

The time evolution of the electron density and the optical emission intensity in response to a square wave modulated RF excitation of helium-silane mixtures has been studied and compared to that for the more conventional CW discharge. In addition, the films deposited from CW and modulated RF glows have-been compared on the basis of absorption coefficients and photoconductivities. Films deposited from modulated glows at substrate temperatures below 200°C have significantly smaller optical bandgaps than those deposited from comparable CW discharges. The bulk electron density in the modulated discharge undergoes a complex temporal variation and its time average value can be significantly larger than that in the CW glow despite the lower average power. A dissociative attachment process involving silane radicals, SiHn (n = 1 to 3), is identified as the most probable cause.
The Relationship Between Emission Spectroscopy and Optical Properties of Amorphous Carbon Films
Authors: Roth Richard M. , Jarman Richard H.
Published: March 2011

Emission from CH and H radicals was monitored during the deposition of amorphous carbon films in a capacitively coupled rf glow discharge. Both the spectral and spatial distributions of the emission were studied. The relative intensity of the CH and H emission was found to be sensitive to changes in discharge parameters. Preliminary results indicate a correlation between the ratios of the CH to H emission intensities and the optical properties of the deposited films.
Plasma Studies in Vacuum ARC Remelting
Authors: Williamson Rodney L. , Zanner Frank. J. , Bertram Lee A. , Peebles Henry C.
Published: March 2011

The visible and UV plasma emissions from a metal vapor arc were studied during vacuum arc remelting of 165 mm diameter Inconel 718 electrodes using emission spectroscopy. Internal energy distributions of a number of emitting species were analyzed using Boltzmann statistics. Analysis of the data yielded distribution “temperatures” ranging from 5,400 K to 8,200 K for the neutral atomic arc species, whereas values of 12,200 K to 17,500 K were obtained for singly ionized species. These values illustrate that the arc is not in a state of local thermodynamic equilibrium. The excited state densities of various arc constituents were measured and it was found that highly volatile alloy trace components, such as Mn, were present in the arc in dispro-portionately high concentrations. These data suggest that ionized evaporates play an important role in carrying current between the electrodes.
High Power Glow Discharge Using Gas Injection Multiple Porous Electrodes
Authors: Harry J. E. , Evans D. R.
Published: March 2011

Glow discharges have been operated at power inputs of 25 kW at 50 mb and discharge currents up to 2 A at gas flow rates of up to 0.04 kg/s in a 100 mm diameter cavity 0.5 m long. This has been made possible by the use of multiple anodes and cathodes combined with gas injection at the porous anodes. Power loading in excess of 700 kW/kg/s have been achieved. The power density of the gas (W/m3) and the current at which the glow to arc transition occurs scaled with both the number of electrode pairs and the gas flow rate through the porous anodes over the range of investigation.
Melting Phenomena of Several Nickel Base Alloys in a Plasma Jet Operating at Low Pressure
Authors: Smith Ronald W. , Apelian Diran
Published: March 2011

The modeling of powders melting in a plasma jet has received increasing attention as the plasma spraying is being developed to produce high density, high performance materials. These models are being used to predict process capability for melting powders and to develop plasma processing parameters for complete particle melting. Most models assume splherical powder particles which heat and melt uniformly during their travel in the plasma jet. The results of this research indicate this assumption may be invalid. Several experiments conducted to evaluate the melting behavior of nickel and nickel alloy powders (Ni,Ni2OCu, Ni2OCr, Ni5O Cr, Rene'80) are presented.
Multiple Paternity within Field-Collected Egg Cases of the Praying MantidTenodera aridifolia
Authors: Watanabe Eisuke , Adachi-Hagimori Tetsuya , Miura Kazuki , Maxwell Michael R , Ando Yoshikazu , Takematsu Yoko
Published: March 2011

We developed microsatellite loci to examine the occurrence of multiple paternity in the praying mantid Tenodera aridifolia Stoll, as inferred from the genotypes of the progeny within field-collected oothecae (egg cases). The microsatellite locus MTA, developed from field-caught mantids, was found to have three alleles (A, B, and C) among >600 hatchlings from 18 oothecae from two locations in Japan. Of the 18 oothecae, two show clear evidence of multiple sires, two show equivocal evidence of multiple sires, and the remaining 14 do not show evidence of multiple sires. Thirteen of the latter 14 oothecae are exclusively homozygous, with all progeny being of the same genotype (BB). Although the exclusively homozygous oothecae suggest a high incidence of monogamy in these field populations, we caution that we probably underestimated the incidence of multiple paternity, given our use of one locus with three alleles. This study is the first genetic investigation of field-collected progeny of a sexually cannibalistic species, as well as the first demonstration of multiple paternity in nature for a sexually cannibalistic species.
Effects of Predators and Injury Over Different Time Scales in the Damselfly Ischnura posita (Odonata: Coenagrionidae)
Authors: Sesterhenn Timothy M
Published: March 2011

Sublethal appendage injury or loss has been shown to alter many behaviors of animals, including foraging and predation avoidance. But most studies of this phenomenon to date have been short-term in scope, and longer term studies may produce different results as seen in some studies on predator effects. Larval damselflies routinely autotomize their caudal lamellae and encounter predators, making them ideal for comparisons of short-term and longer term effects of appendage loss and predator exposure. In this study, I examined activity and foraging of larval Ischnura posita (Hagen) (Odonata: Coenagrionidae), testing for effects of lamella loss and predator cues both in the short term (1 h) and the longer term (8 d). I predicted that both predators and injury would decrease activity and foraging for a short time and that these effects would diminish over time. Results indicated that only the most severe injuries affected foraging, delaying first prey capture when no predator was present; but injury did not affect total prey caught. In the 1-h experiment, damselflies had lower activity in the presence of predator cues, with no effect of injury, whereas the 8-day experiment showed no effect of predator cues on activity. I did not find a major effect of injury or predator cues on activity or foraging of larval damselflies; no effects were detectable over the entire 8-d study. I conclude that the ecological implications of such injuries in nature may often be negligible.
Genetic Basis Regulating the Sex Pheromone Blend in Ostrinia zealis (Lepidoptera: Crambidae) and Its Allies Inferred from Crossing Experiments
Authors: Tabata J , Ishikawa Y
Published: March 2011

To gain insight into the genetic basis of the divergence of sex pheromone signals in the genus Ostrinia, we conducted crossing experiments between three congeners: Ostrinia zealis (Guenée), Ostrinia zaguliaevi Mutuura & Munroe, and Ostrinia sp. near zaguliaevi. Female sex pheromones of the three species are comprised of three common components—(Z)-9-tetradecenyl acetate, (E)-11-tetradecenyl acetate, and (Z)-11-tetradecenyl acetate—blended at species-specific ratios: 70:24:6 in O. zealis, 45:5:50 in O. zaguliaevi, and 19:6:75 in O. sp. near zaguliaevi. The differences between O. zealis and O. zaguliaevi blends, and O. zealis and O. sp. near zaguliaevi blends, could be explained by a single autosomal locus with three alleles. However, sex chromosomal as well as autosomal genes should be taken into consideration to explain the difference between O. zaguliaevi and O. sp. near zaguliaevi blends. From analyses of the fatty acyl precursors of pheromone components, it seems that these genetic factors are involved in the last steps of pheromone biosynthesis including reduction. The process of divergence of pheromone components in the genus Ostrinia is discussed with reference to the findings of previous studies.
Phylogenetic Relationships and Relictualism of Rock-Crawlers (Grylloblattodea: Grylloblattidae) in Cave and Mountain Habitats of Korea
Authors: Schoville Sean D , Kim Byung-Woo
Published: March 2011

Rock-crawlers (Grylloblattodea: Grylloblattidae) in northeastern Asia are low-vagility insects that are restricted to cool temperate forests and mountainous regions. Morphologically distinguishable species are similar ecologically and show narrow endemism and a patchy distribution. As a result, grylloblattids are hypothesized to be relict species that have persisted in situ over long periods of climatic and geological change (Storozhenko and Oliger 1984). We investigate whether the diversification pattern of Asian grylloblattids reflects long-term persistence and divergence due to geological events, or more recent diversification in response to climatic change. Using multilocus genetic data, we examine the phylogenetic relationship to other Asian Grylloblattidae and the geographic pattern of diversification of Korean rock-crawlers, Galloisiana Caudell & King (1924) and Namkungia Storozhenko & Park (2002). Our analysis reveals a monophyletic grouping of Korean species, with multiple cryptic lineages and restricted geographical distributions. Based on genetic data, Korean species are closely related to Japanese Galloisiana. Using a Bayesian relaxed clock model calibrated with a mitochondrial substitution rate, the age of the most recent common ancestor of the Korean—Japanese lineage is estimated within the Miocene epoch. This provides evidence for a diversification event closely tied to the geological events separating the Japanese archipelago from the Korean peninsula.
Discovery of a New Gall-Inducing Species in the Inquiline Tribe Synergini (Hymenoptera: Cynipidae): Inconsistent Implications from Biology and Morphology
Authors: Abe Y , Ide T , Wachi N
Published: March 2011

A new gall-inducing species of the inquiline tribe Synergini (Hymenoptera: Cynipidae), Synergus itoensis Abe, Ide & Wachi, sp. nov., from Japan is described. The morphological features of the adult clearly indicate that this new species is assigned to the genus Synergus Hartig, 1840, and members of Synergini have all been known as inquilines to date. Field observation showed that adult emergence of this gall wasp from acorns of the evergreen oak, Quercus (Cyclobalanopsis) glauca Thunberg, on the ground is well synchronized with the rapid growth period of fresh acorns in late summer. A rearing experiment demonstrated gall induction by S. itoensis in the seed coat of the acorn of Q. (C.) glauca under field conditions. Moreover, the occurrence of arrhenotoky in this gall wasp and lack of a significant effect of gall induction on acorn size were indicated. Judging from the inconsistency of biological and morphological features in S. itoensis, gall-inducing ability might have been regained within Synergini. The advantages and disadvantages of gall induction in acorns are discussed.
Hepaticites iporangae n. sp., Rio Bonito Formation, Early Permian (Sakmarian), Paraná Basin, Brazil, Western Gondwana
Authors: Ricardi-Branco Fresia , Faria Rafael Souza , Jasper André , Guerra-Sommer Margot
Published: March 2011

The formal description of a liverwort from the Paraná Basin is presented. The fossil was found in the Rio Bonito Formation, Early Permian (Sakmarian), and is identified as a new species of the genus Hepaticites, named H. iporangae n. sp. The samples studied were collected from the macrofossil-rich roof-shale layer of the Quitéria Outcrop in the municipality of Encruzilhada do Sul, state of Rio Grande do Sul, Brazil. H. iporangae is one of the oldest liverworts reported from South America. The fossil described here provides more evidence of the relative diversity of liverworts in Paleozoic Gondwana despite the severe climatic conditions during the glaciations of the Permo-Carboniferous.
Problematica, trace fossils, and tubes within the Ediacara Member (South Australia): redefining the ediacaran trace fossil record one tube at a time
Authors: Sappenfield Aaron , Droser Mary L. , Gehling James G.
Published: March 2011

Ediacaran trace fossils are becoming an increasingly less common component of the total Precambrian fossil record as structures previously interpreted as trace fossils are reinterpreted as body fossils by utilizing qualitative criteria. Two morphotypes, Form E and Form F of Glaessner (1969), interpreted as trace fossils from the Ediacara Member of the Rawnsley Quartzite in South Australia are shown here to be body fossils of a single, previously unidentified tubular constructional morphology formally described herein as Somatohelix sinuosus n. gen. n. sp. S. sinuosus is 2-7 mm wide and 3-14 cm long and is preserved as sinusoidal casts and molds on the base of beds. Well-preserved examples of this fossil preserve distinct body fossil traits such as folding, current alignment, and potential attachment to holdfasts. Nearly 200 specimens of this fossil have been documented from reconstructed bedding surfaces within the Ediacara Member. When viewed in isolated hand sample, many of these specimens resemble ichnofossils. However, the ability to view large quantities of reassembled and successive bedding surfaces within specific outcrops of the Ediacara Member provides a new perspective, revealing that isolated specimens of rectilinear grooves on bed bases are not trace fossils but are poorly preserved specimens of S. sinuosus. Variation in the quality and style of preservation of S. sinuosus on a single surface and the few distinct characteristics preserved within this relatively indistinct fossil also provides the necessary data required to define a taphonomic gradient for this fossil. Armed with this information, structures which have been problematic in the past can now be confidently identified as S. sinuosus based on morphological criteria. This suggests that the original organism that produced this fossil was a widespread and abundant component of the Ediacaran ecosystem.
Plug-in-Hybrid Vehicle Use, Energy Consumption, and Greenhouse Emissions: An Analysis of Household Vehicle Placements in Northern California
Authors: Williams Brett , Martin Elliot , Lipman Timothy , Kammen Daniel
Published: March 2011

We report on the real-world use over the course of one year of a nickel-metal-hydride plug-in hybrid—the Toyota Plug-In HV—by a set of 12 northern California households able to charge at home and work. From vehicle use data, energy and greenhouse-emissions implications are also explored. A total of 1557 trips—most using under 0.5 gallons of gasoline—ranged up to 2.4 hours and 133 miles and averaged 14 minutes and 7 miles. 399 charging events averaged 2.6 hours. The maximum lasted 4.6 hours. Most recharges added less than 1.4 kWh, with a mean charge of 0.92 kWh. The average power drawn was under one-half kilowatt. The greenhouse gas emissions from driving and charging were estimated to be 2.6 metric tons, about half of the emissions expected from a 22.4-mpg vehicle (the MY2009 fleet-wide real-world average). The findings contribute to better understanding of how plug-in hybrids might be used, their potential impact, and how potential benefits and requirements vary for different plug-in-vehicle designs. For example, based on daily driving distances, 20 miles of charge-depleting range would have been fully utilized on 81% of days driven, whereas 40 miles would not have been fully utilized on over half of travel days.
Assessing the Impacts of Local Knowledge and Technology on Climate Change Vulnerability in Remote Communities
Authors: Bone Christopher , Alessa Lilian , Altaweel Mark , Kliskey Andrew , Lammers Richard
Published: March 2011

The introduction of new technologies into small remote communities can alter how individuals acquire knowledge about their surrounding environment. This is especially true when technologies that satisfy basic needs, such as freshwater use, create a distance (i.e., diminishing exposure) between individuals and their environment. However, such distancing can potentially be countered by the transfer of local knowledge between community members and from one generation to the next. The objective of this study is to simulate by way of agent-based modeling the tensions between technology-induced distancing and local knowledge that are exerted on community vulnerability to climate change. A model is developed that simulates how a collection of individual perceptions about changes to climatic-related variables manifest into community perceptions, how perceptions are influenced by the movement away from traditional resource use, and how the transmission of knowledge mitigates the potentially adverse effects of technology-induced distancing. The model is implemented utilizing climate and social data for two remote communities located on the Seward Peninsula in western Alaska. The agent-based model simulates a set of scenarios that depict different ways in which these communities may potentially engage with their natural resources, utilize knowledge transfer, and develop perceptions of how the local climate is different from previous years. A loosely-coupled pan-arctic climate model simulates changes monthly changes to climatic variables. The discrepancy between the perceptions derived from the agent-based model and the projections simulated by the climate model represent community vulnerability. The results demonstrate how demographics, the communication of knowledge and the types of ‘knowledge-providers’ influence community perception about changes to their local climate.
Cytotoxic and Antimicrobial Activity of Pseudopterosins and seco-Pseudopterosins Isolated from the Octocoral Pseudopterogorgia elisabethae of San Andrés and Providencia Islands (Southwest Caribbean Sea)
Authors: Correa Hebelin , Aristizabal Fabio , Duque Carmenza , Kerr Russell
Published: March 2011

To expand the potential of pseudopterosins and seco-pseudopterosins isolated from the octocoral Pseudopterogorgia elisabethae of San Andrés and Providencia islands (southwest Caribbean Sea), we report the anti-microbial profile against four pathogenic microorganisms (Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans) and report a more complete cytotoxic profile against five human cells lines (HeLa, PC-3, HCT116, MCF-7 and BJ) for the compounds PsG, PsP, PsQ, PsS, PsT, PsU, 3-O-acetyl-PsU, seco-PsJ, seco-PsK and IMNGD. For the cytotoxic profiles, all compounds evaluated showed moderate and non-selective activity against both tumor and normal cell lines, where PsQ and PsG were the most active compounds (GI50 values between 5.8 µM to 12.0 µM). With respect to their anti-microbial activity the compounds showed good and selective activity against the Gram-positive bacteria, while they did not show activity against the Gram-negative bacterium or yeast. PsU, PsQ, PsS, seco-PsK and PsG were the most active compounds (IC50 2.9–4.5 µM) against S. aureus and PsG, PsU and seco-PsK showed good activity (IC50 3.1–3.8 µM) against E. faecalis, comparable to the reference drug vancomycin (4.2 µM).
Antiplasmodial Natural Products
Authors: Nogueira Cláudio R. , Lopes Lucia M. X.
Published: March 2011

Malaria is a human infectious disease that is caused by four species of Plasmodium. It is responsible for more than 1 million deaths per year. Natural products contain a great variety of chemical structures and have been screened for antiplasmodial activity as potential sources of new antimalarial drugs. This review highlights studies on natural products with antimalarial and antiplasmodial activity reported in the literature from January 2009 to November 2010. A total of 360 antiplasmodial natural products comprised of terpenes, including iridoids, sesquiterpenes, diterpenes, terpenoid benzoquinones, steroids, quassinoids, limonoids, curcubitacins, and lanostanes; flavonoids; alkaloids; peptides; phenylalkanoids; xanthones; naphthopyrones; polyketides, including halenaquinones, peroxides, polyacetylenes, and resorcylic acids; depsidones; benzophenones; macrolides; and miscellaneous compounds, including halogenated compounds and chromenes are listed in this review.
Tannins of Constant Structure in Medicinal and Food Plants—Hydrolyzable Tannins and Polyphenols Related to Tannins
Authors: Okuda Takuo , Ito Hideyuki
Published: March 2011

In addition to the commonly used classification as hydrolyzable tannins and condensed tannins, tannins can also be categorized into two other types: polyphenols of constant chemical structure (Type A) and polyphenols of variable composition (Type B). Both types of tannins and related polyphenols account for a large part of plant polyphenols, but accurate structure-activity correlations on a molecular basis can be determined mainly for type A compounds, among which are hydrolysable tannins such as the ellagitannins and their oxidized congeners, some gallotannins, epigallocatechin gallate, caffetannins, etc. Among the activities determined on a molecular basis are the chemical, biological and pharmacological actions such as superoxide anion scavenging, apoptosis, antitumor, anti-EVB, anti-MRSA and anti-plasmin inhibitory activities, etc., in addition to their fundamental activities, i.e., binding to proteins, large molecular compounds and metallic ions, and antioxidant activities. Some structure-specific activities were found for the condensation of dehydroellagitannins with co-existing compounds under mild conditions, and the host-mediated antitumor actions of ellagitannin oligomers. Structures and activities of metabolites of geraniin, a dehydroellagitannin, were revealed. Some stilbenoids and phlorotannins of firm structures have been known to have many activities similar to those of the type A tannins.
Myocardial Opioid Receptors in Conditioning and Cytoprotection
Authors: Williams-Pritchard Grant , Headrick John P. , Peart Jason N.
Published: March 2011

Opioid compounds and G-protein coupled opioid receptors (ORs) have been studied widely in terms of central nervous system (CNS) actions relating to pain management and drug abuse. Opioids are also linked to induction of mammalian hibernation, a natural state of tolerance involving prolonged and orchestrated shifts in cellular metabolism, growth and stress resistance. It is not surprising then that OR agonism induces acute or delayed cytoprotective states in myocardium, rendering ORs an attractive target for protection of cardiac tissue from the potentially fatal consequences of ischemic heart disease. Cardiac ORs are implicated in triggering/mediating so-called ‘conditioning’ responses, in which powerful cytoprotection arises following transient receptor ligation prior to or immediately following ischemic insult. These responses involve one or more OR sub-types engaging pro-survival kinase cascades to ultimately modulate cell stress and mitochondrial end-effectors. However, important questions remain regarding the role of endogenous opioids, OR signalling, and the transduction and mediation of these protective responses. We briefly review opioid-mediated cardioprotection, focussing on recent developments in signal transduction, the role of receptor ‘cross-talk’, and the effects of sustained OR ligand activation.
Roughness Mapping on Various Vertical Scales Based on Full-Waveform Airborne Laser Scanning Data
Authors: Hollaus Markus , Aubrecht Christoph , Höfle Bernhard , Steinnocher Klaus , Wagner Wolfgang
Published: March 2011

Roughness is an important input parameter for modeling of natural hazards such as floods, rock falls and avalanches, where it is basically assumed that flow velocities decrease with increasing roughness. Seeing roughness as a multi-scale level concept (i.e., ranging from fine-scale soil characteristics to description of understory and lower tree layer) various roughness raster products were derived from the original full-waveform airborne laser scanning (FWF-ALS) point cloud using two different types of roughness parameters, the surface roughness (SR) and the terrain roughness (TR). For the calculation of the SR, ALS terrain points within a defined height range to the terrain surface are considered. For the parameterization of the SR, two approaches are investigated. In the first approach, a geometric description by calculating the standard deviation of plane fitting residuals of terrain points is used. In the second one, the potential of the derived echo widths are analyzed for the parameterization of SR. The echo width is an indicator for roughness and the slope of the target. To achieve a comparable spatial resolution of both SR layers, the calculation of the standard deviation of detrended terrain points requires a higher terrain point density than the SR parameterization using the echo widths. The TR describes objects (i.e., point clusters) close but explicitly above the terrain surface, with 20 cm defined as threshold height value for delineation of the surface layer (i.e., forest floor layer). Two different empirically defined vegetation layers below the canopy layer were analyzed (TR I: 0.2 m to 1.0 m; TR II: 0.2 m to 3.0 m). A 1 m output grid cell size was chosen for all roughness parameters in order to provide consistency for further integration of high-resolution optical imagery. The derived roughness parameters were then jointly classified, together with a normalized Digital Surface Model (nDSM) showing the height of objects (i.e., trees) above ground. The presented approach enables the classification of forested areas in patches of different vegetation structure (e.g., varying soil roughness, understory, density of natural cover). For validation purposes in situ reference data were collected and cross-checked with the classification results, positively confirming the general feasibility of the proposed vertical concept of integrated roughness mapping on various vertical levels. Results can provide valuable input for forest mapping and monitoring, in particular with regard to natural hazard modeling.
Nanofluidic Refractive-Index Sensors Formed by Nanocavity Resonators in Metals without Plasmons
Authors: Tsai Shih-Pin , Ma Yao-Feng , Sung Ming-Je , Huang Ding-Wei
Published: March 2011

Nanocavity resonators in metals acting as nanofluidic refractive-index sensors were analyzed theoretically. With the illumination of transverse electric polarized light, the proposed refractive index sensor structure acts as a pure electromagnetic resonator without the excitation of surface plasmons. The reflected signal from the nanocavity resonators can be very sensitive to the refractive index of the fluids inside the nanocavities due to the enhancement of the electric field of the resonant mode inside the cavities. Such a sensor configuration can be a useful tool for probing the refractive index change of the fluid inside the nanocavities using the spectral, angular or intensity interrogation schemes. The wavelength sensitivity of 430 nm/RIU, angular sensitivity of 200–1,000 deg/RIU and intensity sensitivity of 25.5 RIU−1 can be achieved in the proposed sensor configuration.
The Role of Genetic Drift in Shaping Modern Human Cranial Evolution: A Test Using Microevolutionary Modeling
Authors: Smith Heather F.
Published: March 2011

The means by which various microevolutionary processes have acted in the past to produce patterns of cranial variation that characterize modern humans is not thoroughly understood. Applying a microevolutionary framework, within- and among-population variance/covariance (V/CV) structure was compared for several functional and developmental modules of the skull across a worldwide sample of modern humans. V/CV patterns in the basicranium, temporal bone, and face are proportional within and among groups, which is consistent with a hypothesis of neutral evolution; however, mandibular morphology deviated from this pattern. Degree of intergroup similarity in facial, temporal bone, and mandibular morphology is significantly correlated with geographic distance; however, much of the variance remains unexplained. These findings provide insight into the evolutionary history of modern human cranial variation by identifying signatures of genetic drift, gene flow, and migration and set the stage for inferences regarding selective pressures that early humans encountered since their initial migrations around the world.