bluuebunny/crossref_metadata_2025 huggingface dataset:
Attraction and oviposition of Ephestia kuehniella induced by volatiles identified from chocolate products
Authors: Christian Olsson P.‐O. , Anderbrant Olle , Löfstedt Christer
Published: April 2006

Host‐plant volatiles or other volatiles that attract moths, especially females, could be useful as trap baits or as a complement to pheromones in pest management. Three chocolate products, which had previously been found to be attractive to other pyralid moths, were screened by combined gas chromatography‐electrophysiology for compounds that could be used for trapping of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) moths. Nine compounds were identified as electrophysiologically active using the antennae of both sexes of E. kuehniella. Three of them, namely, benzyl alcohol, nonanal, and phenylacetaldehyde (PAA), showed a clear dose‐dependent electroantennogram (EAG) response on both female and male antennae. In addition, vanillin and ethyl vanillin were electrophysiologically active on male antennae. A blend of benzyl alcohol, nonanal, and PAA was found to trap males in a small‐scale tent experiment. Females were not trapped, but oviposition was induced by each of the three volatiles individually. The results indicate that the volatiles show potential to be used in monitoring of E. kuehniella.
Metabolite mobilization in the stem galls of Parthenium hysterophorus induced by Epiblema strenuana inferred from the signatures of isotopic carbon and nitrogen and concentrations of total non‐structural carbohydrates
Authors: Raman A. , Madhavan S. , Florentine S.K. , Dhileepan K.
Published: April 2006

Parthenium hysterophorus L. (Asteraceae) is a weed of national significance in Australia. Among the several arthropod agents introduced into Australia to control populations of P. hysterophorus biologically, Epiblema strenuana Walker (Lepidoptera: Tortricidae) is the most widespread and abundant agent. By intercepting the normal transport mechanisms of P. hysterophorus, the larvae of E. strenuana drain nutrients, other metabolic products, and energy, and place the host plant under intense metabolic stress. In this study, determinations of total non‐structural carbohydrates (TNC) levels and carbon and nitrogen isotope ratios of fixed products in different parts of the plant tissue, including the gall, have been made to establish the function of gall as a sink for the nutrients.

Values of δ13C and δ15N in galls were significantly different than those in proximal and distal stems, whereas the TNC levels were insignificant, when measured in the total population of P. hysterophorus, regardless of plant age. However, carbon, nitrogen, and TNC signatures presented significant results, when assayed in different developmental stages of P. hysterophorus. Carbon isotope ratios in galls were consistently more negative than those from the compared plant organs. Nitrogen isotope ratios in galls, on the contrary, were either similar to or less negative than the compared plant organs, especially within a single host‐plant stage population (i.e., either rosette, preflowering, or flowering stage). TNC levels varied within compared plant populations. The stem distal to the gall functioned more efficiently as a nodal channel than the stem proximal to the gall, especially in the translocation of nitrogenous nutrients. Our findings indicate that the gall induced by E. strenuana functions as a sink for the assayed nutrients, although some variations have been observed in the patterns of nutrient mobilization. By creating a sink for the nutrients in the gall, E. strenuana is able to place the overall plant metabolism under stress, and this ability indicates E. strenuana has the necessary potential for use as a biological‐control agent.
Distributions and interactions of the stem miners Psylliodes chrysocephala and Ceutorhynchus pallidactylus and their parasitoids in a crop of winter oilseed rape (Brassica napus)
Authors: Ferguson Andrew W. , Barari Hassan , Warner Douglas J. , Campbell James M. , Smith Emma T. , Watts Nigel P. , Williams Ingrid H.
Published: April 2006

The within‐field spatio‐temporal distributions and relationships of two pest insects with stem‐mining larvae, Psylliodes chrysocephala (L.) (Coleoptera: Chrysomelidae) and Ceutorhynchus pallidactylus (Marsham) (Coleoptera: Curculionidae), and their larval endoparasitoids, Tersilochus microgaster (Szépligeti) and Tersilochus obscurator Aubert (Hymenoptera: Ichneumonidae), respectively, were studied in a crop of winter oilseed rape [Brassica napus L. (Brassicaceae)]. The insects were sampled, at different life stages, at 40 spatially referenced points within the oilseed rape in 1998–99 and in the following crop of winter wheat. Distributions were analysed and compared using SADIE (Spatial Analysis by Distance IndicEs) and by tests of edge distribution. Tersilochus microgaster emerged from overwintering by the end of March and T. obscurator from mid April to mid May 2000. Tersilochus microgaster parasitized 10.8% of P. chrysocephala larvae, peak parasitism occurring in May. The distribution of each species was patchy and irregular. Psylliodes chrysocephala and its parasitoid were closely associated, but new generation C. pallidactylus and T. obscurator were less so, probably because of host mortality caused by the parasitoid. The two host–parasitoid pairs showed distributions that were polarized with respect to each other. The genesis of these spatial patterns is discussed in relation to the influence of wind direction, plant size, and interspecific interactions. The potential of these parasitoids as biocontrol agents in integrated pest management is discussed. Opportunities for conservation biocontrol in oilseed rape offered by spatio‐temporal targeting of insecticides to avoid parasitoids and by reduced soil tillage are examined.
Student perspectives on their recent dental outreach placement experiences
Authors: Smith M. , Lennon M. A. , Brook A. H. , Ritucci L. , Robinson P. G.
Published: April 2006

Background:  Dental schools are developing new curricula, with outreach placements enhancing the hospital‐based training.

Objectives:  To assess the students’ experience of outreach as one component of determining the value and feasibility of outreach placements.

Intervention:  Six‐week block placements for 10 undergraduates and 3 weeks for 11 hygiene and hygiene and therapy students in existing primary care clinics, in areas of need, to work supervised by local dentists.

Methods:  Semi‐structured interviews with 20 students by staff independent of the course team. Interviews were audio‐recorded, transcribed and content analysed before being verified by a second observer. Findings were triangulated against a peer‐run focus group and students’ clinical records.

Results:  Students were very positive about their experience and the potential role of outreach training in dental education. They described: gaining greater experience of new types of patients and their communities; learning from broader clinical experience, alternative approaches and practicing or observing dentistry in different settings; the benefits of team working; and, acquiring a more holistic and pragmatic view of health care. Many students reported gaining greater confidence, wider awareness of potential careers in dentistry and a greater sense of realism in their experience. Some reflected on their own training needs. Students also discussed the importance of preparation for the placements and the merits of different styles of supervision.

Conclusion:  Dental outreach training can provide students with valuable learning experience in a range of areas. It requires careful management to ensure those experiences match individuals’ needs and the programme's purposes.
The Development of the English Love Lyric, 1580–1680
Authors: Crouch Patricia
Published: April 2006

This essay was runner‐up in the 2005 Literature Compass Graduate Essay Prize, Renaissance Section.

In the classical and Petrarchan love lyrics’ depiction of the relationship between the desiring lover and his normatively scornful beloved, early modern poets discovered a vehicle for exploring the English social and political order as well as the boundaries between tradition and innovation. As poets from Philip Sidney onward discovered, the social, political, and gender hierarchization of early modern society could be rehearsed as well as confronted in the symbolic staging of a relationship between dominant and submissive parties of opposite sexes. At the same time, the deep enmeshment of the love lyric in the humanist practice of imitatio engendered an abiding reverence for past models while simultaneously urging authors to achieve poetic independence. In the verse of writers like Philip Sidney, John Donne, Mary Wroth, Thomas Carew, Richard Lovelace, and the Earl of Rochester, the interplay between the changing structures of English life and the individual's relation to those structures is registered in a dialectical engagement between modern verse and its models in a movement paralleling the interactions between the fictive lovers who form its subject matter.
‘Exile‐and‐return’ and English Law: The Anglo‐Saxon Inheritance of Insular Romance
Authors: Ashe Laura
Published: April 2006

This article offers a new interpretation of the development of insular romance, drawing on texts and events in the pre‐Conquest period to suggest a much greater degree of cultural continuity across the Conquest than has previously been recognised. One strand of recent scholarship has elucidated the prevalence of the ‘exile‐and‐return’ theme in twelfth‐ and thirteenth‐century insular French romance, and the political force of this ideology. Another has discussed the tendency of thirteenth‐ and fourteenth‐century Middle English romance to construct the Anglo‐Saxon past as a legal golden age, using this trope to support a strong national identity. This article suggests that both of these tropes – the exile‐and‐return of the king, and the idea of good English Law – are in fact not post‐Conquest inventions, as has been assumed, but are rather derived from pre‐Conquest events and texts. This is a part of the author's general contention that a strong English identity can be seen to have survived the Conquest, and to have been expressed in French and Latin throughout the twelfth century, before the literary revival of English. Here it is argued that the two ideas are fundamentally intertwined, are essentially English, and are a genuine inheritance from the Anglo‐Saxon past, in a manner which has not previously been acknowledged.
Educational gerontology: a professional imperative in education for the older Australian learner
Authors: Engelbrecht Cappy
Published: April 2006

Education and training are seen as having a vital role to play in preparing consumers and educators to think differently about ageing, and in reducing ageism. Institutions have a responsibility to respond to this challenge by applying the principles of educational gerontology through specialist adult educators. Educational gerontology, concerned with the education of older adults, public education about ageing and the education of those in the field of ageing, also has the potential to mediate across disciplines in order to generate a platform for collaborative educational activities that ultimately empower the older Australian.
Strong and weak lifespan extension: what is most feasible and likely?
Authors: Lucke Jayne C , Hall Wayne
Published: April 2006

Recent advances in biomedical science indicate that it may eventually be possible to intervene in the biological process of human ageing. This paper overviews the current state of the science of lifespan extension and promising future directions. It is uncertain whether ‘strong’ lifespan extension – the extension of human life beyond the maximum 122 years so far observed – will become a reality. It is more likely that cumulative effects of numerous scientific and biomedical advances in the treatment of common disease will produce ‘weak’ lifespan extension – the extension of average life expectancy. The practical application of molecular, genetic and nanomaterials research may also lead to advances in life expectancy. It is not too early to begin to consider the policy implications of either form of lifespan extension.
Dementia in the news: the media coverage of Alzheimer's disease
Authors: Kirkman Allison M
Published: April 2006

Objective:  To identify and analyse the contexts in which Alzheimer's disease is portrayed in the New Zealand print media.

Methods:  Items from 15 newspapers from over a 5‐year period, which contained the word ‘Alzheimer's’, were subjected to a qualitative interpretive analysis to determine recurring patterns of the representation of Alzheimer's disease.

Results:  The word ‘Alzheimer's’ was found in notices, scientific reports, obituaries, personal stories, ‘missing people’ reports and reports dealing with residential care for people with Alzheimer's disease. The advocacy organisation, Alzheimers New Zealand, was called upon frequently by the media to speak for people with Alzheimer's disease and their families.

Conclusion:  The analysis revealed that the media remains a powerful transmitter of stereotypes. In the case of Alzheimer's disease these included those associated with ageing and with dementia.
Formula Supplemented with Docosahexaenoic Acid (DHA) and Arachidonic Acid (ARA): A Critical Review of the Research
Authors: Wright Kristen , Coverston Catherine , Tiedeman Mary , Abegglen Jo Ann
Published: April 2006

PURPOSE.  To summarize results of randomized controlled trials (RCTs) evaluating growth, cognitive, neurological, and visual development of term infants supplemented with docosahexaenoic acid (DHA) and arachidonic acid (ARA).

DESIGN AND METHODS.  The Boyack and Lookinland Methodological Quality Index (MQI) was used to evaluate data from RCTs identified from multiple data bases.

RESULTS.  Six of ten studies found the addition of DHA and ARA to have no significant effect on infant development.

PRACTICE IMPLICATIONS.  More expensive formula with endogenous DHA and ARA is not necessary. Results from longer studies currently underway will be beneficial.
Enhancing Intervention Fidelity: A Means of Strengthening Study Impact
Authors: Horner Sharon , Rew Lynn , Torres Rosamar
Published: April 2006

PURPOSE.  Intervention studies that address the goals of the Healthy People initiative are increasing, and many focus on health concerns of children and adolescents. The purpose of this paper is to present strategies and discuss the rationale for including intervention fidelity in study design.

CONCLUSION.  Researchers need to verify that their interventions were delivered as designed (intervention fidelity), and that variations from the design can be assessed. Infidelity can result in non‐significant findings that are not due to the study design but rather to elements that affected the intervention delivery.

IMPLICATIONS.  Addressing intervention fidelity in study design supports the researcher's conclusion about associations between intervention and outcomes and helps reduce premature abandonment of potentially useful interventions.
The Effects of Weapons of Mass Destruction on Children
Authors: Mueller Carolyn R.
Published: April 2006

PURPOSE.  Children are especially vulnerable to the effects of chemical and biological weapons of mass destruction (WMD) because of physiologic, pharmacologic, and developmental characteristics. Presentation of signs and symptoms of exposure to biological and chemical agents are similar to those seen in adults. Pediatric considerations for decontamination and treatment of child victims of biological and chemical agents are discussed.

CONCLUSION.  As front‐line providers, nurses need to be aware of potential agents, their uses and effects as WMD, and recommended treatments.

PRACTICE IMPLICATIONS.  Understanding the additional physiologic and situational needs of children, nurses can optimize the survival and outcomes of children when disaster strikes.
A comparative study of the egg morphology in four species of Eubothrium (Cestoda: Pseudophyllidea) with comments on their early development
Authors: Kuchta Roman , Shinn Andrew P. , Hanzelová Vladimíra , Scholz Tomáš
Published: April 2006

Abstract. Freshly released eggs from four species of the cestode Eubothrium (Eubothrium crassum, Eubothrium fragile, Eubothrium rugosum, and Eubothrium salvelini) were subjected to morphological and morphometric analysis. The eggs of the two freshwater species, E. rugosum and E. salvelini, were ovoid with a lobed embryophore whereas the eggs of the two marine species, E. crassum and E. fragile, were more circular with a smooth embryophore. However, the morphological differences between species were not readily evident to permit their clear distinction from one another. To discriminate species, a forward stepwise linear discriminant analysis, using six of the seven measured metric characters made on the eggs, was used, which gave 100% correct classification of two species, E. rugosum and E. salvelini, and a high proportion of correct classification for E. crassum (98%) and E. fragile (83%). Of the latter two species, one specimen of E. crassum and five specimens of E. fragile were misclassified between the respective groups. The principal characters used in the classification of the species were the width of the egg, the length of the mediolateral hooks, and the width of the oncosphere. To provide more information on the life cycle of each species, the eggs were used in a series of infection trials to identify appropriate intermediate hosts. Experimental infections with freshwater copepods were successful when exposed to the eggs of E. salvelini, partially successful when exposed to the eggs of marine E. crassum with 10% of the copepods becoming infected, but no infections were obtained when the eggs of E. fragile were used.
Embryonic development and shell differentiation in Chione cancellata (Bivalvia, Veneridae): an ultrastructural analysis
Authors: Mouëza Marcel , Gros Olivier , Frenkiel Liliane
Published: April 2006

Abstract. The embryonic development in Chione cancellata, from fertilization to straight‐hinge D‐stage veliger larva, occurs in 24 h at 25°C. Transmission (TEM) and scanning (SEM) electron microscopy show that morphogenetic processes result in a gastrula with two depressions, 4 h after fertilization (T0+4 h). Two hours later, one depression, located at the animal pole, develops into an open cave, the floor of which becomes the shell field, characterized by scarce microvilli, located below the lower face of the prototrochal pad. The invagination located at the vegetal pole is characterized by regular microvilli and constitutes the digestive tract. At T0+8 h, the late gastrula differentiates into a typical motile trochophore, possessing a well‐developed prototroch delimiting anterior and posterior embryonic regions. At T0+9 h, the shell field, located between the prototroch and the telotroch, appears as a saddle‐shaped region with a wrinkled surface extending on both sides of the embryo, establishing bilateral symmetry. From TEM observations, the apical surface of the underlying cells possesses a modified glycocalyx featuring a dense pellicle overlapping the cells of the shell field. At T0+12 h, the prototroch is displaced toward the anterior region by outgrowth of the shell material. TEM views show that the wrinkled surface observed with SEM corresponds to the periostracum, attached dorsally to the hinge and ventrally to the cells of the future mantle edge. At T0+15 h, an alveolar matrix of proteinaceous material, which could contain calcite crystals, appears between the periostracum and the mantle. At T0+24 h, prodissoconch I formation is completed and the D‐stage larvae possess a calcified shell. At this stage of development, only one mantle fold is present, representing the outer fold. The periostracum‐secreting cells are in contact with the marginal cells of the velum. This functional velum is composed of four bands of cilia. Our TEM observations confirm previous descriptions of the velum ciliary bands obtained only from SEM analyses, such as described in other bivalves. The apical sense organ and the digestive tract are poorly developed. From observations at the ultrastructural level of shell differentiation in C. cancellata, we propose a new interpretation of shell differentiation, including hinge and ligament for bivalves as opposed to that described for gastropods.
First report of the aberrant association of branchiobdellidans (Annelida: Clitellata) on blue crabs (Crustacea: Decapoda) in Chesapeake Bay, Maryland, USA
Authors: Gelder Stuart R. , Messick Gretchen
Published: April 2006

Abstract.This is the first article of branchiobdellidans on blue crabs,Callinectes sapidus, in Chesapeake Bay, MD, USA. The ectosymbionts consisted of sympatric populations ofCambarincola mesochoreusandCambarincola pamelaeliving on the ventral body surface and in the gill chambers of blue crabs. The occurrence of branchiobdellidans in the upper bay region was documented at ten sites during August and late September 2003. Branchiobdellidans were found on blue crabs following a rainy summer when salinity levels fell below 3 ppt. The blue crabs move into the freshwater estuaries during the summer, where they enter the habitats of crayfishes; however, the mechanism of transfer from one crustacean host to another is not known.
Phylogenetic relationship of 16 Oedipodidae species (Insecta: Orthoptera) based on the 16S rRNA gene sequences
Authors: LU HUI‐MENG , HUANG YUAN
Published: April 2006

Abstract
The sequences of the mitochondrial 16S rRNA gene of 16 Oedipodidae species were amplified and sequenced. All sequences were aligned and analyzed and the phylogenetic relationships were inferred. The properties of 16S gene in Oedipodidae showed typical patterns of many insects such as a high A+T content and variable distance‐dependent transition/transversion ratios. The 0.2 weight for sites of loops may be advisable for phylogeny reconstruction using the maximum parsimony method. The phylogenetic analysis results do not support the current subfamily classification systems of Oedipodidae. Bryodemellinae and Bryodeminae are closely related and should be merged as one subfamily. The status of Oedipodinae and Locustinae is also problematic.
IMPROVING THE QUALITY OF PORK HAM BY PULSED VACUUM COOLING IN WATER
Authors: CHENG QIAOFEN , SUN DA‐WEN
Published: April 2006

Vacuum cooling of pork ham with water, or immersion vacuum cooling, is a successful method to compensate the high mass loss of traditional vacuum cooling. In order to further optimize vacuum cooling with water, pulsed vacuum cooling was designed to study the effect of different cycles on the quality of pork ham, i.e., in one cycle, four cycles and eight cycles. The result indicated that increasing pulse cycles during vacuum cooling of pork ham with water would reduce the cooling loss with compatible cooling time. Tests on the physical properties of pork ham disclosed that tenderness and water‐holding capacity could be improved by increasing pulse cycles during vacuum cooling with water. However, There was no significant difference observed between pork ham in 4 pulse cycles and 8 pulse cycles (P > 0.05). Therefore, treatment of 4 pulse cycles was adopted for future research related to vacuum cooling of pork ham with water.
QUALITIES OF EXTRUDED PUFFED SNACKS FROM MAIZE/SOYBEAN MIXTURE
Authors: OBATOLU VERONICA A. , OMUETI OLUSOLA O. , ADEBOWALE EBENEZER A.
Published: April 2006

A maize‐based snack was fortified with partially defatted soybean (PDS) at 10, 20 and 30% of total weight and analyzed for physical (expansion ratio, density, color and texture [brittleness, breaking strength and hardness]), chemical and sensory characteristics. Incorporating PDS in a maize‐based snack had a positive effect on chemical properties but had a negative effect on the physical and sensory characteristics. The results showed a protein range of 9.3 ± 0.90% in 100% maize‐based snacks to 19.3 ± 1.03% in 30% replacements with soybean. The overall consumer acceptability test showed a score range between 4.1 ± 0.82 in 30% level of fortification and 8.2 ± 1.04 in 100% maize and 10% fortified extrudate. Panelists perceived the puffed extrudates with 20 and 30% PDS as not puffy or crispy, less acceptable and harder to crack. Up to 20% of PDS could be used in maize‐based puffed extrudates.
ALTERNATIVE PRETREATMENT METHODS TO ENZYMATIC TREATMENT FOR CLARIFICATION OF MOSAMBI JUICE USING ULTRAFILTRATION
Authors: RAI P. , MAJUMDAR G.C. , JAYANTI V.K. , DASGUPTA S. , DE S.
Published: April 2006

A series of pretreatment methods to mosambi juice were undertaken and results were compared to pectinase treatment for clarification of the treated juice using ultrafiltration. The pretreatment methods attempted were centrifugation, centrifugation followed by addition of gelatin, centrifugation followed by addition of bentonite, centrifugation followed by fining using both bentonite and gelatin and enzymatic treatment, using pectinase as the enzyme. A systematic study was undertaken to select the operating centrifugation speed and time. The permeate flux and quality of the permeate were comparable to the enzyme‐treated juice.
1
A
∕
cm
2
current density from microgated carbon nanotube field-emitter arrays grown by dc plasma chemical-vapor deposition
Authors: Hsu David S. Y. , Shaw Jonathan L.
Published: April 2006

We report improved emission performance of microgated carbon nanotube field-emitter arrays. The arrays with 0.1mm2 areas produced anode currents in excess of 1mA (1A∕cm2) and transconductance of up to 174μS (174mS∕cm2) at gate voltages of 75V or less. The carbon nanotubes were grown by dc plasma chemical-vapor deposition, but were not oriented vertically during inspection in the scanning electron microscope. Most of the nanotubes had diameters near 10nm. We suggest that the small tube diameter caused the relatively high emission current and also produced limber tubes, unable to support themselves vertically.
Fabrication of active-matrix high-efficiency electron emission device and its application to high-sensitivity image sensing
Authors: Negishi Nobuyasu , Tanaka Ryota , Nakada Tomonari , Sakemura Kazuto , Okuda Yoshiyuki , Satoh Hideo , Watanabe Atsushi , Yoshikawa Takamasa , Ogasawara Kiyohide , Nanba Masakazu , Okazaki Saburo , Tanioka Kenkichi , Egami Norifumi , Koshida Nobuyoshi
Published: April 2006

Practical advantages of an advanced high-efficiency electron emission device (HEED) (low-voltage operation, relatively simple structure, and availability for large-area applications) are further confirmed by its compatibility with active-matrix drive configuration. The fabricated HEED array has been applied to a high-sensitivity image sensing tube with a target of high-gain avalanche rushing amorphous photoconductor (HARP). It is demonstrated that a prototype 256×192pixel active-matrix HEED array operates well as an effective probe for high-resolution image pickup in combination with a HARP target. The advanced HEED array is promising for development of next-generation image sensor with ultrahigh sensitivity and high definition.
Nanofabrication module integrated with optical aligner
Authors: Stuart Colin , Xu Qianfei , Tseng Ricky J. , Yang Yang , Hahn H. Thomas , Chen Yong , Wu Wei , Williams R. Stanley
Published: April 2006

In this article, we describe a simple module that can be integrated with a commercial optical aligner for nanoimprint lithography or optical lithography. The module provides a convenient low-cost technique to transform an optical aligner for microfabrication into a nanofabrication machine. This combination enables the creation of nanoscale features and alignment of multiple-layer lithographic patterns with submicron accuracy within one instrument. Imprinting of 30 nm half-pitch lines has been demonstrated by the module, as well as submicron alignment. The module has also been used to fabricate micro- and nanoscale patterns simultaneously by the combination of optical and imprint lithography.
Synthesis and emission properties of carbon nanotubes grown by sandwich catalyst stacks
Authors: Chen Zexiang , Cao Guichuan , Lin Zulun , den Engelsen Daniel
Published: April 2006

We report in this article a method to grow carbon nanotubes (CNTs), which are well aligned and vertically oriented. Furthermore, these CNTs have a uniform length and diameter. A sandwiched catalyst structure is utilized to form multiwalled carbon nanotubes. It is feasible to grow CNTs between two terminals directly and grow straight vertical carbon nanotube bundles. The transmission electron microscope image of the as-grown CNTs shows a typical multiwalled CNT lattice structure with a few defects. After treating the as-grown CNTs in an ammonia radio-frequency plasma, a highly stable field-emission current density of more than 6A∕cm2 at an electric field of 7.7V∕μm with a total field-emission current of >1.2mA was obtained. Our experiments indicate a fabrication route for largely improving the field-emission characteristics of CNT-based field emitters.
Growth characteristics of carbon nanotubes on nanotip-formed substrate
Authors: Sato Hideki , Matsubayashi Mai , Sakai Takamichi , Hata Koichi , Miyake Hideto , Hiramatsu Kazumasa , Oshita Akinori , Saito Yahachi
Published: April 2006

Growth property of carbon nanotubes onto silicon substrate on which nanotips were formed was examined under an intention to control growth of carbon nanotubes (CNTs). Nanotips were formed onto substrate by reactive ion etching (RIE). The RIE treatment on the surface gave densely formed nanosized tips. After the nanotip formation, CNTs were grown on the substrate by microwave plasma-enhanced chemical-vapor deposition. The growth characteristics of the CNTs depended on size of the nanotips. The results showed that the CNTs grown on the substrate with the nanotip formation give smaller diameter and growth density than those grown without nanotips.
Real-time reflectometry-controlled focused-electron-beam-induced deposition of transparent materials
Authors: Perentes A. , Bret T. , Utke I. , Hoffmann P. , Vaupel M.
Published: April 2006

An optical in situ technique is presented for monitoring the optical thickness of transparent materials during focused-electron-beam (FEB)-induced deposition. Three precursors were used: formic acid [HCOOH], tetramethyl orthosilicate [Si(OCH3)4], and titanium nitrate [Ti(NO3)4]. Two of them led to optically interesting materials for ultraviolet or visible applications. By cofocusing a laser (514nm) with the scanning FEB in the plane of the sample, we continuously monitored the intensity of the reflected light during deposit growth. Periodic intensity variations due to interference effects as function of deposit thickness were observed and interpreted. Complex-refractive indices at the 514nm wavelength of the materials deposited from HCOOH, Si(OCH3)4, and Ti(NO3)4 were calculated from the periodic signal and were, respectively, 1.51+i0.055, 1.56+i0.14, and 2.19+i0.013.
Statistical variation analysis of sub-5-nm-sized electron-beam-induced deposits
Authors: van Dorp W. F. , van Someren B. , Hagen C. W. , Kruit P. , Crozier P. A.
Published: April 2006

We report on the statistical analysis of the variations in the size and position of sub-5nm tungsten-containing dots in regular arrays deposited by electron-beam-induced deposition. Full widths at half maximum of the dots are 4.2 and 2.0nm in average. It can be observed in the recorded annular dark-field images that there is a variation in intensity for these dots. We have analyzed these variations and it is found that the relative standard deviation for the mass per dot is 0.092 for the 4.2nm dots and 0.26 for the 2.0nm dots. Comparing this to a relative standard deviation in the estimated number of precursor molecules that are pinned down per dot of 0.041 for the 4.2nm dots and 0.11 for the 2.0nm dots, it appears that the dot-to-dot variation in mass for both dot sizes compares reasonably well with the values expected from Poisson statistics on the number of molecules per dot. It can be concluded that at these dimensions, the statistics on the number of pinned precursor molecules dominates the control of feature sizes.
Self-organized Cu nanowires on glass and Si substrates from sputter etching Cu/substrate interfaces
Authors: Stepanova M. , Dew S. K.
Published: April 2006

We have fabricated self-organized ∼30-nm-wide Cu lines on glass and Si(100) substrates by Ar beam etching the Cu/substrate interfaces. We deposited thin Cu layers on the substrates and etched the deposited layer by a neutralized Ar ion beam at a grazing angle of incidence. At the stage when almost all Cu is removed by etching, we have observed Cu lines on the substrate. The lines orientation is entirely controllable through the experiment geometry and the lines are basically similar on glass and Si substrates. By atomistic Monte Carlo simulations, we have demonstrated that the Cu lines result from the self-organized morphologies that develop on Cu surfaces during sputter etching. To better understand ways to control the process we have investigated, by simulations, the line width as a function of the removed depth, surface diffusivity, and Ar beam flux. We have concluded that the sputter etch technique offers a unique opportunity to fabricate controlled arrays of Cu lines on substrates.
Use of SiO2 nanoparticles as etch mask to generate Si nanorods by reactive ion etch
Authors: Liang Eih-Zhe , Huang Chao-Jei , Lin Ching-Fuh
Published: April 2006

Silicon nanorods 20nm in diameter are fabricated by reactive ion etch (RIE) to study anisotropy and damage profile in decananometer scale. RIE of gas mixture of SF6∕O2 and SF6∕CHF3 is tuned to achieve high anisotropy. The gas specie of SF6∕O2 can reach 90% anisotropy, 84° taper angle, and 10:1 selectivity when SiO2 is used as the etching mask. The gas species of SF6∕CHF3 can reach 95% anisotropy, 87° taper angle, and 10:1 selectivity with Cr as the mask. The fabrication technique of nanorods uses a monolayer of silicon dioxide nanoparticle as the etching mask. The nanorods uniformly cover up the entire 2in. wafers with high density of 2×1011cm−2. Surface damageafter the etching process of nanostructures is monitored using the microwave-reflectance photoconductance decay with KOH removal-and-probe technique. Highly damaged silicon is found within a depth of 30nm and the lightly damaged part extends more than 100nm.
Three primary color luminescence from natively and thermally oxidized nanocrystalline silicon
Authors: Sato Keisuke , Hirakuri Kenji
Published: April 2006

Three primary color luminescence from nanocrystalline silicon (nc-Si) prepared by hydrofluoric (HF) acid solution and subsequent oxidation treatments were studied using photoluminescence and Fourier transform infrared spectroscopy measurements. HF-treated nc-Si exhibited stable and strong red luminescence in the air. When the HF-treated nc-Si surface was oxidized by native and/or thermal treatment, the luminescence color varied continuously from red to blue. The reason is the enlargement of the effective band gap energy because of a reduced particle size caused by surface oxidation. The blue and green luminescence of thermally oxidized nc-Si could be distinctly seen in the air with the naked eye. These results suggest that the HF and post-thermal oxidation treatments can realize good stability and higher brightness in the air for three primary color luminescence from nc-Si.
Nanoseconds field emitted current pulses from ZrC needles and field emitter arrays
Authors: Ganter R. , Bakker R. J. , Betemps R. , Dehler M. , Gerber T. , Gobrecht J. , Gough C. , Johnson M. , Kirk E. , Knopp G. , Le Pimpec F. , Li K. , Paraliev M. , Pedrozzi M. , Rivkin L. , Sehr H. , Schulz L. , Wrulich A.
Published: April 2006

The properties of the electron source define the ultimate limit of the beam quality in linear accelerators such as free electron lasers (FELs). The goal is to develop an electron gun delivering beam emittance lower than the current state of the art. Such a gun should reduce the cost and size of an x-ray FEL (XFEL). In this article we present two concepts of field emitter cathodes which could potentially produce low emittance beam. The first challenging parameter for such cathode is to emit peak current as high as 5 A. This is the minimum current requirement for the XFEL concept from Paul Scherrer Institut (http://leg.web.psi.ch). Maximum currents of 0.12 and 0.58 A have been reached, respectively, with field emitter arrays and single needle cathodes. Laser assisted field emission gave encouraging results to reach even higher peak current and to prebunch the beam.
Effects of a nanocomposite carbon buffer layer on the field emission properties of multiwall carbon nanotubes and nanofibers grown by hot filament chemical vapor deposition
Authors: Uppireddi Kishore , González-Berríos Adolfo , Piazza Fabrice , Weiner Brad R. , Morell Gerardo
Published: April 2006

The electron field emission properties of multiwall carbon nanotubes (MWCNTs) grown on sulfur-incorporated nanocomposite carbon (n-C:S) buffer layer were investigated. Both the MWCNTs and the n-C:S films were synthesized in a hot filament chemical vapor deposition system at relatively low methane concentrations. The n-C:S buffer layer provides good contact and adhesion to the Mo substrate and good contact and interface to the MWCNTs. The presence of this buffer layer was shown to improve the reproducibility and stability of the field emission behavior of MWCNTs. The turn-on field (EC) varies as much as 1.1V∕μm after high current density operation when there is no buffer layer, but variations up to only 0.3V∕μm are observed when the buffer layer is present. These results are interpreted in terms of the n-C:S buffer layer role, providing good adhesion and contact to the substrate side and to the MWCNTs, hence ensuring a high density of continuous paths for electrons from the substrate to the MWCNTs.
Role of neutral molecule chemistry in electron cyclotron resonance microwave plasmas capable of diamond deposition
Authors: Blumenthal R. , Webb S. F.
Published: April 2006

The chemical compositions of 4% carbon in hydrogen/deuterium electron cyclotron resonance (ECR) microwave plasmas based on ethane, ethylene, acetylene, and methane, as determined by supersonic pulse, plasma sampling mass spectrometry, have been kinetically modeled using only a steady-state concentration of hydrogen to represent the role of the plasma. Using 375 isotopically labeled chemical steps based on 54 reversible neutral molecule chemical reactions, simulated spectra were generated that matched all eight experimental spectra using only literature values of the kinetic and energetic constants and three physically reasonable fitted parameters that were held constant for all eight simulations. The success of the modeling provides strong evidence that the chemistry of ECR-microwave plasmas is dominated by neutral molecule reactions.
rf microelectromechanical system device with a lateral field-emission detector
Authors: Yamashita Kiyotaka , Sun Winston , Kakushima Kuniyuki , Fujita Hiroyuki , Toshiyoshi Hiroshi
Published: April 2006

We propose a micromachined device that utilizes the field-emission (FE) phenomenon as a mean to modulate signal for radio-frequency microelectromechanical system applications. In this article, we present the stationary reference (SR) device and the resonator-embedded (RE) device and compare their field-emission performances. The SR device contains no moving part and is used to examine the conditions to excite field emission. The RE device has an embedded microresonator of bandpass filter characteristic. Due to enhanced tip sharpness and closer gap, initial results show that compared to the SR device, the FE current of the RE device has been increased by 192 times under the same anode-cathode potential difference of 240V and 2×10−8Torr vacuum level.
Total energy distribution of field emission electrons from a film of carbon nanopearls
Authors: Mouton R. , Semet V. , Guillot D. , Binh Vu Thien
Published: April 2006

Compared to other graphitic nanostructures, in particular, the tubular geometry of carbon nanotubes, the nanopearls forming a three-dimensional foamlike material have the advantage of presenting statistically a high density of apex areas with a small radius of curvature (∼75nm) when deposited at the end of a tip. This structure is suitable for a self-repairing cathode working at high currents. The field emission study was performed in a conventional field emission microscope equipped with an energy analyzer. After a conditioning process, currents up to 50μA can be obtained under continuous emission, and the variation of the field emission current with the applied voltage strictly followed the conventional Fowler-Nordheim behavior, i.e., a linear variation of ln(I∕V2) vs (1∕V). A systematic analysis of the total energy distribution spectra under different conditions has been done. For current emitted from a single nanopearl at the end of one string, the full width at half maximum (FWHM) of the single peak total energy distribution spectra is ∼0.2eV and it is position dependent on the string resistance. From the convolution of independent sources, associated to the foamlike structure of the carbon nanopearls, the total energy distribution spectra present a multiple peak structure with a global FWHM values from 0.5to1eV.
Mo
∕
Al
∕
Mo
∕
Au
Ohmic contact scheme for AlxGa1−xN∕GaN high electron mobility transistors annealed at 500 °C
Authors: Basu A. , Mohammed F. M. , Guo S. , Peres B. , Adesida I.
Published: April 2006

Low-resistance Ohmic contacts on Al0.3Ga0.7N∕GaN high electron mobility transistors (HEMTs) were formed with a Mo∕Al∕Mo∕Au metallization scheme which was annealed at a relatively low temperature of 500 °C. A contact resistance of 0.11±0.05Ωmm and a specific contact resistivity of 2.63×10−7Ωcm2 were achieved. This represents the best low-temperature-annealed Ohmic contacts on GaN-based HEMTs achieved to date.
Fabrication of sub-transistor via holes for small and efficient power amplifiers using highly selective GaAs∕InGaP wet etching
Authors: Uchiyama Hiroyuki , Ohta Hiroshi , Shiota Takashi , Takubo Chisaki , Tanaka Kenichi , Mochizuki Kazuhiro
Published: April 2006

We investigated the properties of a citric acid-based GaAs∕InGaP selective wet etchant. We found that the citric acid-based etchant has a much higher selectivity and exhibits less undercutting than those of a conventional sulfuric acid-based etchant that we had used. Then, we applied the citric acid-based wet etchant to the fabrication of via holes with high thermal diffusibility underneath heterojunction bipolar transistors. The citric acid-based etchant exhibited GaAs∕InGaP selectivity of about 9800 at pH 9.0 and enabled reliable etch stopping without pinholes. The citric acid-based etchant also suppressed undercutting and enabled the integration of the via holes. We used the optimized citric acid-based wet etching for finishing the via hole etching after rough high-speed wet etching with the conventional sulfuric acid-based etchant. The two-step wet etching process resulted in a successful fabrication of the sub-transistor via hole structure with collector-up heterojunction bipolar transistors.
Gas phase chemomechanical modification of silicon
Authors: Lee Michael V. , Richards Jody L. , Linford Matthew R. , Casey Sean M.
Published: April 2006

In this work we demonstrate the gas phase chemomechanical functionalization of silicon. This work streamlines the preparation of chemomechanically modified surfaces, in comparison with previously described liquid phase modifications. Scribing was performed in the presence of ethylene, acetylene, and a control (air). X-ray photoelectron spectroscopy, wetting, and time-of-flight secondary ion mass spectrometry (scores and loadings from principal components analysis) results are consistent with expectations and with previous analysis of samples scribed under liquid alkenes and alkynes. Thermal desorption spectroscopy analysis supports the Si(100) model for scribed silicon.
Electron beam induced deposition of pure, nanoscale Ge
Authors: Ketharanathan Sutharsan , Sharma Renu , Crozier P. A. , Drucker Jeff
Published: April 2006

Pure, nanoscale Ge dots were deposited on Si3N4 substrates by decomposing digermane (Ge2H6) using a focused electron beam. Deposited feature diameters are larger than that of the electron beam used for deposition by an amount comparable to the secondary electron escape depth. This result suggests that axial secondary electron emission through the surface of a growing feature limits the minimum attainable feature size. In situ, electron energy-loss spectroscopy shows that the dots are pure Ge with C contents below the carbon detection limit of less than 18%. Analyzing the bright field image in the thin film, single scattering approximation yields the height of the Ge dots allowing the average Ge deposition efficiency to be estimated.
Assembled microelectromechanical system microcolumns for miniature scanning electron microscopies
Authors: Saini R. , Jandric Z. , Gory I. , Mentink S. A. M. , Tuggle D.
Published: April 2006

We report an assembled microelectromechanical system (MEMS) electrostatic microcolumn design that employs a multiwall carbon nanotube emitter as an electron source. The microcolumn is designed for a beam diameter of 10–20 nm with a beam energy of 1 keV at currents of up to 1 nA and a 100μm field of view. The maximum voltage on any microcolumn component is ±1kV. The microcolumn components are fabricated on a single 50μm thick silicon on insulator wafer and are assembled to the prefabricated, self-aligning sockets in the device layer using MEMS grippers and connectors to realize an inexpensive and compact microcolumn. The electron beam traverses the entire microcolumn without exposure to any insulator. We have successfully assembled components of this design and operational testing is currently in progress.
Vertically aligned carbon nanotube arrays for giant field emission displays
Authors: Mauger Matthieu , Binh Vu Thien
Published: April 2006

Direct growth of individual and vertically aligned carbon nanotubes (CNT) onto a metallic tip apex using a two-chamber radio-frequency plasma-enhanced chemical vapor deposition reactor is reported. Individual Ni nanocatalysts were the sites for the nucleation of individual CNTs that were freestanding, clean, and vertically aligned by the presence of a controlled applied field. To understand the role of the electric field during the growth of these individual vertically aligned CNTs, we have separated the plasma production from the applied electric field to the CNTs, by the use of the two-chamber reactor. Our results suggest that the growth direction is mainly related to the ion implantation of carbon species in the metal catalyst located on the top of the CNTs. In this model, the direction of ion implantation fixes the distribution of the concentration gradient of carbon atoms across the nanocatalyst particle, i.e., the direction and the growth velocity of the CNTs. Moreover, it lessens the role of surface decomposition and dissolution of the feed gas. For a polarized substrate the growth direction is then vertical to the surface. The obtained arrays of CNTs, having a low-density spatial distribution to avoid mutual electrostatic field screening, gave uniform and stable overall field emission patterns after a conditioning process. Effective total current densities up to 1A∕cm2 can be extracted.