bluuebunny/crossref_metadata_2025 huggingface dataset:
Ungulate browsing on European silver fir Abies alba: the role of occasions, food shortage and diet preferences
Authors: Häsler Helene , Senn Josef
Published: March 2012

European silver fir Abies alba is the most heavily browsed conifer in Central European mountain forests. Attempts to reduce ungulate browsing have often been unsuccessful, controversial or too costly. The aim of the work described here was to improve our understanding of the factors that lead to browsing on silver fir. The silver fir content in the diet of three sympatric ungulate species, chamois Rupicapra rupicapra, red deer Cervus elaphus and roe deer Capreolus capreolus, was determined by microhistological analysis of faeces collected at four sites in the Alps. Further, the supply of silver fir was assessed at the individual tree and patch scale and then extrapolated to site scale. Silver fir consumption was highest in winter, when diet composition varied among sites but not among ungulate species. Towards the summer, site‐differences decreased and differences among ungulate species increased. Red and roe deer reduced consumption of silver fir, whereas chamois kept it constant. The use of silver fir was unrelated to the supply at the various sites, but increased with the proportion of trees growing amidst palatable herbaceous species. At the individual plant scale, ungulates browsed on the saplings with the larger needles. These results indicate that silver fir as food does not rank high among the available plant species, but is eaten opportunistically, especially when it grows close to more preferred food plants. However, when alternative food is scarce, particularly in winter, it may also represent a shortage food supply, and larger quantities are consumed. Yet, the fact that feeding on silver fir is mostly opportunistic may offer forest managers a way to approach the ‘browsing problem’.
Characteristics of two mountain lion Puma concolor populations in Texas, USA
Authors: Harveson Patricia Moody , Harveson Louis A. , Hernandez‐Santin Lorna , Tewes Michael E. , Silvy Nova J. , Pittman Michael T.
Published: March 2012

Influential factors associated with population dynamics of mountain lions Puma concolor include exploitation rates, prey availability, habitat structure and social structure. Throughout most of North America, mountain lion harvest is regulated by state or provincial quotas or is protected by federal laws. In Texas, however, they are not classified as a game or fur‐bearing animal so their harvest is not regulated. To better understand the differences between population characteristics of mountain lions in west Texas (WTX) and south Texas (STX), we initiated two ecological studies. We captured, radio‐marked and monitored mountain lions to ascertain survival, mortality factors, density, reproduction and population structure. We captured and monitored 19 and 21 mountain lions in the STX and WTX study sites, respectively. Average densities (No/100 km2) were different between our two study sites (STX = 0.269, WTX = 0.427) and were considerably lower than in previous studies. Mortality factors also differed between the two areas; in STX the causes were predominantly hunter harvest compared to trapping in WTX. Seasonal survival rates of mountain lions were lower during the general hunting season (STX = 0.783, WTX = 0.750) than during the non‐hunting season (STX = 0.962, WTX = 0.931). Because population characteristics differed between the two genetically separated populations (Walker et al. 2000), resource managers should consider evaluating regional, rather than statewide management plans for mountain lions in Texas.
Seed removal and survival in Asiatic black bear Ursus thibetanus faeces: effect of rodents as secondary seed dispersers
Authors: Koike Shinsuke , Morimoto Hideto , Kozakai Chinatsu , Arimoto Isao , Yamazaki Koji , Iwaoka Masahiro , Soga Masashi , Koganezawa Masaaki
Published: March 2012

We investigated the fate of seeds of five tree species hill cherry Prunus jamasakura, Korean hill cherry P. verecunda, Japanese bird cherry P. grayana, giant dogwood Swida controversa and crimson glory vine Vitis coignetiae in the faeces of the Asiatic black bear Ursus thibetanus in a temperate forest in central Japan. Clarifying the fate of seeds dispersed by endozoochorous seed dispersers will enhance assessments of their roles as primary seed dispersers. We established several experimental treatments in the field. Each faeces sample was covered by cages with different mesh sizes which limited accessibility by animals (NM: no mesh, SM: 1 mm mesh and MM: 10 mm mesh). We examined whether seed removal varied among tree species and between mesh‐size treatments from 2004 to 2007 (N = 625 samples). We set up an automatic camera trap 1.5 m above the ground at all NM treatments. In the NM treatments, the number of seeds of all tree species decreased immediately after the faeces were set. In June of the following year, < 1% of the seeds from any species remained in the vicinity of the faeces. However, we found 3.0‐13.2% intact seeds of all species in the soil below the faeces, as well as within a 10‐m radius around the faeces. In the NM treatments, most seed removals were observed within four days after the faeces were set. For all tree species in the MM treatment, most of the seeds were present on the surface of the soil, and 1‐2% of the seeds germinated at the location where faeces were set. In the SM treatment, none of the seeds from any of the tree species disappeared and germinated. We took a total of 415 photographs at the NM sites, 97.8% of which were of rodents either holding or eating seeds. Many of the seeds contained in the bear faeces were removed and eaten by rodents. However, 2.1‐5.1% of the seeds survived and germinated, which implies that rodents may also act as secondary seed dispersers.
The role of demographic and environmental variables on the presence of snow tracks by river otters Lontra canadensis
Authors: Crowley Shannon , Johnson Chris J. , Hodder Dexter
Published: March 2012

Unknown causes of heterogeneity in the presence or detection of wildlife tracks and other signs could bias interpretations of population indices derived from surveys. These surveys can be the basis of management decisions for populations of wildlife. However, we know very little about potential biases affecting the presence of tracks in the landscape. We used an Information Theoretic Model Comparison approach to investigate the role of environmental, demographic and behavioural influences on the presence of river otter Lontra canadensis snow tracks in central British Columbia, Canada, from January to March 2008. We repeatedly located five radio‐collared otters and recorded the presence of tracks within an estimated 100‐m radius of the otter's location. We used combinations of five variables to develop logistic regression models that predicted the presence or absence of snow tracks when the location of otters was known. The presence of snow tracks was best described by a model containing covariates for gender and movement distance per day. The probability of detecting snow tracks was higher for male compared to female otters and was positively related to the daily movement distance of the individual animal. Track‐sign heterogeneity among individuals could bias surveys that assess and monitor river otter populations, and should be incorporated into the design and interpretation of track surveys.
Access Without Equity
Authors: Posselt Julie Renee , Jaquette Ozan , Bielby Rob , Bastedo Michael N.
Published: March 2012

The competitive dynamics that sustain stratification among postsecondary institutions have reinforced racial inequality in selective college enrollment between 1972 and 2004. Using a data set constructed from four nationally representative surveys (National Longitudinal Survey 1972, High School & Beyond 1980, National Educational Longitudinal Survey 1988, and Educational Longitudinal Survey 2002), the authors model how escalating admissions standards—including academic preparation and the growing importance of SAT scores and extracurricular leadership—effectively maintain racial inequality in selective college enrollment over time. Black and Latino students have made strides in their pre-collegiate academic preparation. Nevertheless, although access to postsecondary education has expanded since 1972 for all ethnic groups, Black and Latino students’ odds of selective college enrollment have declined relative to White and Asian American students.
SEL as a Component of a Literature Class to Improve Relationships, Behavior, Motivation, and Content Knowledge
Authors: Shechtman Zipora , Abu Yaman Mary
Published: March 2012

The study assesses the effect of social and emotional learning (SEL) integrated in a literature class, named here “affective teaching,” as compared to conventional teaching. Dependent variables include relationships, behavior, motivation to learn, and content knowledge. Participants were 36 teacher trainees in one college in Israel and 1,137 fifth and sixth grade students from 36 classrooms in 12 schools. A hierarchical model of analyses (Mixed Models) was used to assess children’s gains in the two teaching conditions. Results indicated significantly more improvement on all measures for children in the affective teaching condition compared to control. Relationships and behavior were significantly associated with children’s gains in motivation and content knowledge. The discussion focuses on the importance of SEL for children’s development and the potential contribution of affective teaching as a modality of social and emotional learning.
Effect of Resistance Exercises on Function in Older Adults with Osteoporosis or Osteopenia: A Systematic Review
Authors: Wilhelm Mark , Roskovensky Gregory , Emery Karla , Manno Christina , Valek Katherine , Cook Chad
Published: March 2012

Purpose: To examine the effect of resistance exercises on self-reported physical function and activities of daily living (ADL) in older adults with osteoporosis or osteopenia. Methods: A search of available literature was conducted using PubMed, CINAHL, SPORTDiscus, PEDro, ProQuest Nursing and Allied Health Source, and Cochrane Controlled Trials Register. Studies were included if they involved (1) randomized controlled trials; (2) participants with osteoporosis or osteopenia; (3) resistance exercise as an intervention; and (4) self-report of physical function or ADL. Articles were independently reviewed for quality by two authors using the Physiotherapy Evidence Database (PEDro) scale. Cohen's d effect size was calculated by dividing standardized mean differences by the standard deviation to determine treatment effect in terms of physical function or ADL. Results: Five full-text articles were selected for inclusion. PEDro scores ranged from 5 to 7 (out of 10). Effect size mean differences as a result of resistance intervention ranged from 0.08 to 1.74, suggesting “trivial” to “large” effects on self-reported physical function and ADL. Conclusion: Results suggest that interventions using resistance training have a beneficial impact on the domains of physical function and ADL in participants with osteoporosis or osteopenia. More high-quality studies are needed to lend further validity to this supposition.
Biological evaluation of micro-nanoporous layer on Ti–Ag alloy for dental implant
Authors: Moon Seung-Kyun , Kim Chong-Kwan , Joo Uk-Hyon , Oh Keun-Taek , Kim Kyoung-Nam
Published: March 2012

This study examined the biocompatibility of the micro-nanoporous layer formed on a titanium-silver (Ti–Ag) alloy. The porous layer was formed by grit-blasting and anodic oxidation. The surface of the porous layer was rougher and more hydrophilic compared to a simple machined specimen and the expressions of bone-related genes were greater for cells grown on the porous layer compared to that of cells cultured on a control surface. Also the bone-to-plate contact rate in vivo test was significantly improved for porous layer plate compare to simple machined specimen (P < 0.05). The porous layer on Ti–Ag alloy enhanced the peri-implant bone formation at the early healing stage and it was believed that this porous layer on the Ti–Ag alloy will be suitable for dental implant applications.
The reoptimization of the binary Se–Te system
Authors: Gierlotka Wojciech , Wu Wei-Hsiang
Published: March 2012

Selenium–tellurium metal films are promising materials for optical reversible memories; thus, the possibility of modeling of the phase diagram and thermodynamic properties seems to be important for industry. The Calphad method was used for a new thermodynamic assessment of the binary Se–Te system. A good agreement between calculation and experimental information is obtained.
Thermophysical properties of solid phase Ti-6Al-4V alloy over a wide temperature range
Authors: Milošević Nenad , Aleksić Ivana
Published: March 2012

This paper presents experimental results on thermophysical properties of the most commonly used titanium alloy, Ti-6Al-4V, in its solid phase. The subsecond pulse calorimetry has been applied for measuring heat capacity, specific electrical resistivity, and hemispherical total and normal spectral emissivity, and the laser flash method for measuring thermal diffusivity. Specific heat capacity and specific electrical resistivity were measured from 250 to 1700 K, thermal diffusivity from 190 to 1530 K, hemispherical total emissivity from 780 to 1670 K, and normal spectral emissivity at 900 nm from 1300 to 1730 K. Thermal conductivity and Lorentz function were computed from experimental data in the range from about 190 to 1530 K. For necessary corrections literature data on thermal linear expansion were used. The results obtained are compared with available literature values.
Phase diagram of the Sm–Dy–Fe ternary system
Authors: Wang Bowen , Zhu Yulan , Dai Junqiu , Weng Ling , Huang Wenmei , Hao Yanming
Published: March 2012

The isothermal section at 800°C and vertical sections of SmFe2–DyFe2 and (Sm0.86Dy0.14) Fe
x
(1.6 ≤ x ≤ 2.4) in the Sm–Dy–Fe system were determined by using optical microscopy, X-ray diffraction analysis, electron probe microanalysis, and differential thermal analysis techniques. The isothermal section possesses 6 single-phase regions, 7 two-phase regions, and 3 three-phase regions. There are five intermetallic phases: (Sm, Dy) Fe2, (Sm, Dy) Fe3, (Sm, Dy)6Fe23, Th2Zn17-type (Sm, Dy)2Fe17, and Th2Ni17-type (Sm, Dy)2Fe17. No Sm6Fe23 and (Sm, Dy)2Fe7 phases exist in the ternary system. The vertical section of SmFe2–DyFe2 in the Sm–Dy–Fe system contains 2 single-phase regions, 2 two-phase regions, and 1 three-phase region. Investigation of the vertical section of (Sm0.86Dy0.14) Fe
x
(1.6 ≤ x ≤ 2.4) indicates that it consists of 2 single-phase regions, 5 two-phase regions, and 1 three-phase region.
Free-surface enhanced continuum model predicts size-effect for pillar compression at micro- and nano-scale
Authors: Brinckmann Steffen , Siegmund Thomas
Published: March 2012

It has recently been observed that micro- and nano-sized pillars under uniaxial compression and tension attain a higher flow-stress than samples of macroscopic size. Here it is hypothesized that such a mechanical size-effect is driven by the interaction of dislocations with the free surfaces. An extended continuum plasticity theory is presented to account for such an effect by considering the free-surface imagestresses on the dislocation motion immediately following dislocation nucleation. The model employs only fundamental material parameters, Young's modulus, Poisson's ratio, bulk yield-strength, and the Burgers vector. The model predicts the magnitude of the size-effects observed in the compression of Au and Cu micro- and nano-pillars.
Diffusion characteristics in the Cu–Ti system
Authors: Lai Arijit , Bhanumurthy Karanam , Kale Gajanan Balaji , Kashyap Bhagwati Prasad
Published: March 2012

The formation and growth of intermetallic compounds by diffusion reaction of Cu and Ti were investigated in the temperature range 720–860°C using bulk diffusion couples. Only four, out of the seven stable intermediate compounds of the Cu–Ti system, were formed in the diffusion reaction zone in the sequence CuTi, Cu4Ti, Cu4Ti3 and CuTi2. The activation energies required for the growth of these compounds were determined. The diffusion characteristics of Cu4Ti, CuTi and Cu4Ti3 and Cu(Ti) solid solution were evaluated. The activation energies for diffusion in these compounds were 192.2, 187.7 and 209.2 kJ mol−1 respectively, while in Cu(Ti), the activation energy increased linearly from 201.0 kJ mol−1 to 247.5 kJ mol−1 with increasing concentration of Ti, in the range 0.5–4.0 at.%. The impurity diffusion coefficient of Ti in Cu and its temperature dependence were also estimated. A correlation between the impurity diffusion parameters for several elements in Cu matrix has been established.
Effect of pH on structure, morphology and optical properties of nanosized cupric oxide prepared by a simple hydrolysis method
Authors: Gharagozlou Mehrnaz , Rahnama Ahmad
Published: March 2012

A simple hydrolysis process has been developed to prepare nanosized cupric oxide using cupric acetate as a starting material. In addition, the effects of different pH values varying from 5 to 10 and ultrasonic irradiation on the structure, morphology and optical properties of nanosized CuO samples have been investigated. Samples were characterized using X-ray diffraction, Fourier transform spectroscopy, scanning electron microscopy, transmission electron microscopy and UV–Vis spectroscopy. X-ray diffraction patterns of samples were identical to the single-phase pure CuO with a monoclinic structure. Our results indicated that properties of samples had great dependence on the reaction pH and ultrasonic irradiation. The crystallite size increased with increasing the pH value from 5 to 10. The band gap of samples was estimated to be in the range of 2.0–2.9 eV, which is larger than the reported value for bulk CuO. Synthesized CuO samples with adjustable and controllable optical properties make the applicability of cupric oxide even more versatile.
Effect of sand blasting on structural, thermal, and mechanical properties of Zr58.3Cu18.8Al14.6Ni8.3 bulk metallic glass
Authors: Tariq Naeem ul Haq , Awais Hasan Bin , Akhter Javaid Iqbal , Naeem Muhammad , Shahid Rub Nawaz
Published: March 2012

In the present work sand-blasting-induced structural, thermal, and mechanical effects were studied in Zr58.3Cu18.8Al14.6Ni8.3 bulk metallic glass. It was observed that sand blasting favors disordering of the atomic configuration, formation of free volume and evolution of multiple intersecting shear bands. As a result, considerable compressive plasticity was achieved in sand-blasted samples. It was also observed that in order to superimpose the effect of pre-straining and extra free volume for improving compressive plasticity, there exists a limit to both parameters.
High-temperature deformation behavior and thermal properties of an Ni30Co17Fe53 alloy
Authors: Lee Kwang Seok , Yoon Dong Hyun , Jung Joong Eun , Chang Young Won , Lee Jung Hwan
Published: March 2012

High temperature deformation behavior of a Ni30Co17Fe53 alloy has been investigated by carrying out hot compression tests at temperatures ranging from 600°C to 1150°C under strain rates between 10−5 and 1 s−1. Both the temperature and strain-rate dependence of the flow stress were found to be described by a hyperbolic sine function. Hot formability of this alloy was also estimated by constructing an empirical processing map based on a dynamic materials model, from which the region with high power dissipation efficiency was exhibited as a feasible combination of processing condition at around 1150°C and 10−2 s−1. Three different thermo-mechanical treatment processes were adopted for hot-forging to investigate its influence on microstructure and subsequent thermal expansion and thermal conductivity.
Effect of inhomogeneous size and shape of graphite particles on the in-plane electrical conductivity of PP/G/CB composites
Authors: Dweiri Radwan
Published: March 2012

In-plane electrical conductivity higher than 100 S cm−1 for composite bipolar plates is required in fuel cells. The effect of the conductive filler size and shape, as one important factor, on the conductivity of polypropylene/graphite/carbon black (PP/G/CB) composites is investigated in this study. The “as-received” G particles were sieved to different sizes; melt compounded with PP and CB, then compression moulded to plates for conductivity measurements. G particles have different size distributions and their morphology appear with irregular shapes. The intermediate G size and relatively narrow distribution (40–150 μm) shows the highest conductivity at 80 wt.% filler loading of about 88.6 S cm−1. The presence of small G particles between larger ones and the particle's point-to-point and surface-to-surface contacts are found to be important factors in determining the conductivity values. The flexural properties are still below the target and need to be improved.
The durability of fired brick incorporating textile factory waste ash and basaltic pumice
Authors: Binici Hanifi , Yardim Yavuz
Published: March 2012

This study investigates the durability of fired brick produced with additives of textile factories' waste ash and basaltic pumice. The effects of incorporating waste ash and basaltic pumice on durability and mechanical properties of the clay bricks were studied. Samples were produced with different ratios of the textile factories' waste ash and basaltic pumice added and at different fire temperatures of 700, 900, and 1050°C for 8 h. The bricks with additives were produced by adding equal amounts of textile factories' waste ash and basaltic pumice, separately and together, with rates of 5, 10 and 20 wt.%. The produced samples were kept one year in sodium sulphate and sodium nitrate and tested under freezing–unfreezing and drying–wetting conditions. Then compression strength and mass loss of the samples with and without additives were investigated. The test results were compared with standards and results obtained from control specimens. The results showed that incorporations up to 10 wt.% of textile factories' waste ash and basaltic pumice is beneficial to the fired brick. Both textile factories' waste ash and basaltic pumice were suitable additives and could be used for more durable clay brick production at 900°C fire temperature.
Diffusivities and atomic mobilities in Cu-rich fcc Al–Cu–Mn alloys
Authors: Yin Ming , Du Yong , Cui Senlin , Xu Honghui , Zhang Lijun , Liu Shuhong
Published: March 2012

Via solid–solid diffusion couples, electron probe microanalysis and the Whittle and Green method, interdiffusivities in fcc Al–Cu–Mn alloys at 1123 K were measured. The reliability of the obtained diffusivities is validated by comparing the computed diffusivities with literature data plus constraints among the diffusivities. Through assessments of experimentally determined diffusion coefficients by means of a diffusion-controlled transformations simulation package, the atomic mobilities of Al, Cu, and Mn in fcc Al–Cu–Mn alloys are obtained. Comprehensive comparisons between the model-predicted and the experimental data indicate that the presently obtained atomic mobilities can reproduce most of the diffusivities, concentration profiles, and diffusion paths reasonably.
Characterization and catalytic behavior of CuO@SiO2 nanocomposites towards NO oxidation and N2O decomposition
Authors: Tohidi Seyed H. , Grigoryan Garnik L. , Derhambakhsh Maryam
Published: March 2012

A distinct concentration of copper was embedded into silica matrix to form xerogel using Cu(NO3)2 · 3H2O as the copper source. The xerogel samples were prepared by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) by the sol–gel method. The new molar ratio of H2O/TEOS was determined to be 11.67. Also the necessary amount of trihydrated copper nitrate was added into the solution such that the concentration of the copper oxide in the final solution reached 10 wt.%. After ambient drying, the xerogel samples were heated to 100, 400, 600, 800, and 1000°C at a slow heating rate (50 K h−1). The structural properties were characterized by means of transmission electron microscopy, surface analysis and thermal program reduction methods at different temperatures. Finally, the catalytic behavior of nanocomposites was studied for nitrogen oxide (NO) oxidation and di-nitrogen oxide (N2O) decomposition reactions. The results present a systematic reactivity study of NO oxidation and N2O decomposition on the dispersed copper oxide nanocatalysts over silica supports in order to determine the ability of these materials to convert nitrogen oxide and di-nitrogen oxide into harmless species at different temperatures.
A physically based approach to model the incomplete bainitic transformation in high-Si steels
Authors: van Bohemen Stefan M. C. , Hanlon David N.
Published: March 2012

This paper describes an approach to simulate the incomplete bainitic transformation observed in high-Si steels. The model can capture the incomplete transformation when a simple procedure accounting for carbon enrichment in the remaining austenite is applied to calculate the change in the zero transformation temperature, which is a key parameter controlling the transformation kinetics. The carbon concentration in the remaining austenite is determined by the volume fraction of bainitic ferrite and the effective carbon concentration of the bainitic ferrite. Comparison with experimental data for Fe-0.3C-2.4Mn-1.8Si is made, which demonstrates that the isothermal kinetics of bainite formation in the range 370–480°C can be satisfactorily described with the model by using a single set of model parameters and only adjusting the carbon concentration of the bainitic ferrite. A good agreement is found between predicted final carbon contents of retained austenite and those measured using X-ray diffraction, which indicates that a plausible carbon dependency of the zero transformation temperature has been assumed in the calculations.
Self-assembling behavior and corrosion inhibition properties of TDPA films on differently structured surfaces of 2024 and 1060 aluminum alloys
Authors: Qu Jun-e , Wang Hai ren , Zhang Qiang , Yang Li-xia
Published: March 2012

The adsorption and corrosion inhibition behavior of 1–tetradecylphosphonic acid self-assembled monolayers on the differently structured surfaces of 2024 and 1060 aluminum alloys were investigated by contact-angle measurement, potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning electron microscopy coupled with energy-dispersive spectroscopy. The electrochemical experiments showed that a 4 h modification of 2024 and 1060 alloys resulted in a maximal inhibition efficiency. Independent of assembly time, the desorption of the tetradecylphosphonic acid molecules provoked by anodic polarization to a certain degree resulted in the acceleration of the anodic dissolution reaction. The inhibition of the self-assembled monolayers for the 1060 alloy was more prominent than for the 2024 alloy. This is consistent with the contact-angle values, supporting the conclusion that TDPA formed a more closely packed SAM on the surface of the 1060 alloy than of the 2024 alloy. Scanning electron microscopy/energy dispersive X-ray spectroscopy results directly revealed the inhibition effect of the monolayers on the primary corrosion stage of these two alloys.
Study of the mechanism of ductile-regime grinding of SiCp/Al composites using finite element simulation
Authors: Huang Shutao , Zhou Li , Yu Xiaolin , Xu Lifu
Published: March 2012

Based on indentation experiments under different loads, the mechanism of ductile-regime grinding of SiCp/Al composites has been investigated. The factors that influence the ductile-regime removal of SiC particles, such as tip radius of abrasive grains, intrusion depth, and volume fraction of SiC particles, have been analyzed by three-dimensional finite element simulation. The calculation results indicate that a sharp abrasive grain without tip radius cannot produce a plastic deformation region under the indenter and brittle fracture of the SiC particle takes place rather than ductile model of failure. The critical grinding depth of ductile-regime removal decreases with increasing tip radius of abrasive grains, but increases with decreasing SiC particle volume fraction.
Effects of sintering temperature on pore characterization and strength of porous cordierite–mullite ceramics by a pore-forming in-situ technique
Authors: Yan Wen , Luo Hao , Tong Jun , Li Nan
Published: March 2012

Porous cordierite–mullite ceramics with high strength were prepared by a pore-forming in-situ technique. The phase compositions, pore characteristics, and strength were investigated through X-ray diffractometry, scanning electron microscopy, and a microscopy measurement method. It is found that the sintering temperature strongly affects the formation of cordierite and mullite and the sintering, and thus changes the pore characteristics and strength. The formation of cordierite and mullite takes place on a large scale at 1430°C. The pore size distributions are bimodal in specimens sintered at 1370°C, 1400°C, and 1430°C, and mono-modal in a specimen sintered at 1450°C. The strength increases slightly when the sintering temperature increases from 1370°C to 1400°C, and increases significantly when the sintering temperature is increased to 1430°C. The most appropriate mode is a specimen sintered at 1430°C which has high cordierite (42 wt.%) and mullite content (53 wt.%), high apparent porosity (44%), high compressive strength (30.6 MPa) and a relatively homogeneous pore-size distribution.
Morphological study of SiC coating developed on 2D carbon composites using MTS precursor in a hot-wall vertical reactor
Authors: Venugopalan Ramani , Prakash Jyoti , Nuwad Jitendra , Pillai Chirakarumpil Gopalan Sivan , Tyagi Avesh Kumar , Dakshinamoorthy Sathiyamoorthy
Published: March 2012

Silicon carbide coating was developed using chemical vapor deposition on carbon substrate as a protective coating. The present studies were carried out with methyl trichlorosilane as the SiC precursor, at 1673 K along with hydrogen and argon as carrier gas using a high-temperature vertical graphite reactor. The SiC coatings were characterized by means of X-ray diffraction for phase identification. Scanning electron microscopy analysis with energy dispersive X-ray spectrometer was also carried out for microstructure and elemental analysis. From the morphological study of different SiC deposits obtained at varying operating parameters it was observed that methyl trichlorosilane feed rate and hydrogen flow rate play a major role in deciding the nature of deposits and the argon percentage in the mixed gas also plays a vital role.
Sol–gel synthesis of Eu3+, Tb3+ co-doped Y2O3 scintillating nanopowders
Authors: Romo Felipe de Jesús Carrillo , Ramírez Ángel de Jesús Morales , Murillo Antonieta García , Hernández Margarita García , Vigueras David Jaramillo , Febles Vicente Garibay
Published: March 2012

Y2O3: Eu3+, Tb3+ nanopowders were prepared via the sol–gel process, using yttrium pentadionate, europium, terbium nitrates, and ethanol as precursors. After the sol evaporation at 100°C, the formed gel was annealed from 300 to 900°C for 15 min, and the obtained nanopowders were analyzed by X-ray diffraction to characterize the microstructural behavior and the crystalline structure, which was determined as mainly cubic. The crystallite size varies from 8.6 to 30.9 nm, at 500 and 900°C, respectively. Transmission electron microscopy studies were carried out in order to analyze the microstructure and the size of crystallites. Three different Tb3+ atomic contents (0.005, 0.075, and 0.01 at.%) were used at a fixed Eu3+ level (2.5 at.%) with the aim of determining the relationship between the co-doping content and the scintillation intensity of the well-known 5Do→7F2 europium emission band at 611 nm. The results show that at higher Tb3+ contents, a quenching process occurs between Eu3+ and Tb3+; however, even with the lowest Tb3+ content (0.005 at.%), an increment on the scintillation light yield is observed compared with a Eu3+ monodoped sample.
Influence of the layer architecture of DLC coatings on their wear and corrosion resistance
Authors: Bobzin Kirsten , Bagcivan Nazlim , Theiß Sebastian , Weiß Raphael , Depner Udo , Troßmann Torsten , Ellermeier Jörg , Oechsner Matthias
Published: March 2012

In this work, the influence of diamond-like carbon top layers deposited on two different types of layer architecture on wear and corrosion resistance is investigated. Physical vapour deposition coatings with a-C:H top layer of various thicknesses were deposited on plasma nitrided 42CrMo4 by reactive magnetron sputter ion plating. Beneath the top layer, an architecture with and without a-C interlayers was deposited. Investigations using potentiodynamic polarisaton testing in artificial seawater as well as an impact tribometer show that it is possible to protect low-alloy heat treatable steel from both corrosion and wear by using pre-treatment and an appropriate diamond-like carbon coating. Thicker a-C:H top layers as well as the addition of a-C interlayers resulted in an overall improvement in the coating behaviour.
Dynamic behavior of staggered triangular honeycomb cores under in-plane crushing loadings
Authors: Sun Deqiang , Zhang Weihong , Yu Jiang
Published: March 2012

A reliable finite element model was employed to investigate the effects of configuration parameters and impact velocity on the in-plane deformation mode and dynamic plateau stress of staggered triangular honeycomb cores at impact velocities 3–300 m s–1 under in-plane crushing loadings. At different impact velocities, ‘>’-, ‘<’-shaped, and ‘I’-shaped deformation modes appear in turn. The effects of configuration parameters on the deformation modes are discussed qualitatively. When all configuration parameters are kept constant, the mean in-plane dynamic plateau stress is proportional to the square of impact velocity; for a given impact velocity, the mean in-plane dynamic plateau stress is related to the ratio of cell-wall thickness to edge length by power laws and to the expanding angle by complicated curves. Mean in-plane dynamic plateau stresses are expressed by empirical equations in terms of configuration parameters and impact velocity based on our simulation results.
Creep modeling and creep life estimation of Gr.91
Authors: Abe Fujio
Published: March 2012

The creep behavior and deciding factors for creep life have been investigated for Gr.91 in the temperature range between 450 and 725°C. The longest time to rupture was 68755 h. The creep life is inversely proportional to the minimum creep rate multiplied by the increase in creep rate by strain in the acceleration region for a wide range of test temperature and duration. The minimum creep rate depends on both the time to minimum creep rate and the strain to minimum creep rate. The strain to minimum creep rate decreases with decreasing stress, suggesting that the creep deformation in the transient region is significantly inhomogeneous at low stresses. The creep life is correlated with the creep deformation parameters in the transient region so that we can predict the creep life from a short-term creep test for up to the end of transient region, corresponding to less than 30% of the creep life, without any stress extrapolation.
Efficacy of indocyanine green videography and real-time evaluation by FLOW 800 in the resection of a spinal cord hemangioblastoma in a child
Authors: Ueba Tetsuya , Abe Hiroshi , Matsumoto Juntaro , Higashi Toshio , Inoue Tooru
Published: March 2012

A 19-month-old child was gradually suffering from gait disturbance and was referred by his pediatrician to the authors' institution. Spinal MRI showed Gd-enhanced spinal cord tumor and congestive myelopathy. Intraoperatively the lesion was seen to be a hemangioblastoma. Because discrimination of the arterialized draining veins from the feeding arteries was difficult, indocyanine green videography was conducted to differentiate them. Real-time evaluation by FLOW 800 revealed that the slope of the average signal intensity in the feeding artery was steeper than that of the arterialized veins. The tumor was successfully resected, and postoperative indocyanine green videography showed total removal of the tumor as a signal-negative region; the circulation time between the feeding artery and the main draining vein was prolonged from 2.5 to 5.5 seconds. Indocyanine green videography and real-time evaluation by FLOW 800 were objective and effective for the excision of a tumor retaining the arteriovenous shunt. The patient recovered from congestive myelopathy and gait disturbance.
Palliative hemispherotomy in children with bilateral seizure onset
Authors: Ciliberto Michael Anthony , Limbrick David , Powers Alexander , Titus Jeffrey B. , Munro Rebecca , Smyth Matthew D.
Published: March 2012

Object

Intractable epilepsy is a significant burden on families and on the cognitive development and quality of life (QOL) of patients. Periinsular hemispherotomy (PIH) for medically intractable epilepsy can benefit patients who qualify for this procedure. The ideal hemispherotomy candidate has ipsilateral ictal and interictal epileptiform activity, unilateral MR imaging abnormalities, contralateral hemiplegia, and a normal contralateral hemisphere. However, certain patients present with a mixed picture of bilateral electroencephalography (EEG) findings and severe intractable epilepsy, prompting consideration of a more aggressive treatment approach. This report introduces the possibility of surgery for patients who normally would not meet criteria for this treatment modality.

Methods

In this retrospective chart review, the authors report on 7 patients with bilateral seizure onset noted on routine or video-EEG monitoring. A QOL phone questionnaire, based on the Quality of Life in Childhood Epilepsy tool, was administered to a parent. The authors reviewed each patient's chart for surgical complications, changes in examination, QOL, limited neuropsychological outcomes, and seizure outcomes. They also investigated each chart for MR imaging and EEG findings as well as the patient's epilepsy clinic notes for seizure semiology and frequency.

Results

All patients enjoyed a decrease in seizure frequency and a subjective increase in QOL after PIH. Five patients (71%) achieved Engel Class I or II seizure control. The mean follow-up was 3.64 years (2–5.3 years). One patient is now off all antiseizure medication. No patient had a decrement in Full Scale IQ on postsurgical testing, and 2 (28.5%) of 7 individuals had increased adaptive and social functioning. Postsurgical examination changes included hemiplegia and homonymous hemianopia.

Conclusions

Hemispherotomy in patients with intractable epilepsy is generally reserved for individuals with unilateral epileptiform abnormalities or lesions on MR imaging. Seven patients in this study benefited from surgery despite bilateral seizure onset with improvement in seizure control and overall QOL. Thus, bilateral ictal onset does not necessarily preclude consideration for hemispherotomy in selected patients with severe medically refractory epilepsy.
External ventricular drainage alone versus endoscopic surgery for severe intraventricular hemorrhage: a comparative retrospective analysis on outcome and shunt dependency
Authors: Basaldella Luca , Marton Elisabetta , Fiorindi Alessandro , Scarpa Bruno , Badreddine Hadi , Longatti Pierluigi
Published: March 2012

Object

Massive intraventricular hemorrhages (IVHs) require aggressive and rapid management to decrease intracranial hypertension, because the amount of intraventricular blood is a strong negative prognostic predictor on outcome. Neuroendoscopy may offer some advantages over more traditional surgical approaches on outcome and may decrease the number of shunt procedures that need to be performed.

Methods

The authors retrospectively reviewed the clinical and radiological data in 96 patients treated for massive IVH who were admitted between January 1996 and June 2008 to the neurosurgery unit after undergoing emergency CT scanning. Forty-eight patients (Group A) were treated with endoscopic aspiration surgery using a flexible endoscope with a “freehand” technique. A historical group of 48 patients (Group B) treated using external ventricular drain (EVD) placement alone was used as a comparison. The authors compared the radiological results with the clinical outcomes at 1 year according to the modified Rankin Scale and the need for internal CSF shunt treatment in the 2 groups.

Results

Endoscopic aspiration did not significantly affect the outcome at 1 year as determined using the modified Rankin Scale. Patients who underwent endoscopy had an EVD in place for 0.18 days fewer than patients treated with an EVD alone. Patients undergoing external ventricular drainage alone had a 5 times greater chance of requiring a shunting procedure than those treated using neuroendoscopy and external ventricular drainage. Neuroendoscopy plus external drainage reduces shunting rates by 34% when compared with external drainage alone.

Conclusions

The reduction in internal shunt surgery encourages the adoption of neuroendoscopic aspiration of severe IVH as a therapeutic tool to decrease shunt dependency.
Intracerebral hemorrhage secondary to intravenous and endovascular intraarterial revascularization therapies in acute ischemic stroke: an update on risk factors, predictors, and management
Authors: Mokin Maxim , Kan Peter , Kass-Hout Tareq , Abla Adib A. , Dumont Travis M. , Snyder Kenneth V. , Hopkins L. Nelson , Siddiqui Adnan H. , Levy Elad I.
Published: March 2012

Intracerebral hemorrhage (ICH) secondary to intravenous and intraarterial revascularization strategies for emergent treatment of acute ischemic stroke is associated with high mortality. ICH from systemic thrombolysis typically occurs within the first 24–36 hours of treatment initiation and is characterized by rapid hematoma development and growth. Pathophysiological mechanisms of revascularization therapy-induced ICH are complex and involve a combination of several distinct processes, including the direct effect of thrombolytic agents, disruption of the blood-brain barrier secondary to ischemia, and direct vessel damage from wire and microcatheter manipulations during endovascular procedures. Several definitions of ICH secondary to thrombolysis currently exist, depending on clinical or radiological characteristics used. Multiple studies have investigated clinical and laboratory risk factors associated with higher rates of ICH in this setting. Early ischemic changes seen on noncontrast CT scanning are strongly associated with higher rates of hemorrhage. Modern imaging techniques, particularly CT perfusion, provide rapid assessment of hemodynamic parameters of the brain. Specific patterns of CT perfusion maps can help identify patients who are likely to benefit from revascularization or to develop hemorrhagic complications. There are no established guidelines that describe management of revascularization therapy–induced ICH, and great variability in treatment protocols currently exist. General principles that apply to the management of spontaneous ICH might not be as effective for revascularization therapy–induced ICH. In this article, the authors review current knowledge of risk factors and radiological predictors of ICH secondary to stroke revascularization techniques and analyze medical and surgical management strategies for ICH in this setting.
Thrombin and hemin as central factors in the mechanisms of intracerebral hemorrhage–induced secondary brain injury and as potential targets for intervention
Authors: Babu Ranjith , Bagley Jacob H. , Di Chunhui , Friedman Allan H. , Adamson Cory
Published: March 2012

Intracerebral hemorrhage (ICH) is a subtype of stoke that may cause significant morbidity and mortality. Brain injury due to ICH initially occurs within the first few hours as a result of mass effect due to hematoma formation. However, there is increasing interest in the mechanisms of secondary brain injury as many patients continue to deteriorate clinically despite no signs of rehemorrhage or hematoma expansion. This continued insult after primary hemorrhage is believed to be mediated by the cytotoxic, excitotoxic, oxidative, and inflammatory effects of intraparenchymal blood. The main factors responsible for this injury are thrombin and erythrocyte contents such as hemoglobin. Therapies including thrombin inhibitors, N-methyl-D-aspartate antagonists, chelators to bind free iron, and antiinflammatory drugs are currently under investigation for reducing this secondary brain injury. This review will discuss the molecular mechanisms of brain injury as a result of intraparenchymal blood, potential targets for therapeutic intervention, and treatment strategies currently in development.
Controversies in the neurosurgical management of cerebellar hemorrhage and infarction
Authors: Amar Arun Paul
Published: March 2012

Evidence-based guidelines for the management of hemorrhagic and ischemic cerebellar stroke are sparse, and most available data come from Class III studies. As a result, opinions and practices regarding the nature and role of neurosurgical intervention vary widely. A comprehensive literature review was conducted to adjudicate several contentious issues, such as the difference in the management of cerebellar hemorrhage versus infarction, criteria for imaging to exclude an underlying structural lesion, the value of MRI for patient selection, the role of external ventricular drainage, the indications for operative management, the timing of surgical intervention, and various options of surgical technique, among others. Treatment algorithms proposed in several different studies are compared and contrasted. This analysis is concluded by a summary of the recommendations from the American Stroke Association, which advises that patients with cerebellar hemorrhage who experience neurological deterioration or who have brainstem compression and/or hydrocephalus due to ventricular obstruction should undergo surgical evacuation of the hemorrhage as soon as possible, and that initial treatment of such patients with ventricular drainage alone rather than surgical removal of the hemorrhage is not recommended.