Fine Array Research Articles

Dysprosium-free melt-spun permanent magnets

Melt-spun NdFeB powders can be formed into a number of different types of permanent magnet for a variety of applications in electronics, automotive and clean technology industries. The melt-spinning process produces flake powder with a fine uniform array of nanoscale Nd2Fe14B grains. These powders can be net-shape formed into isotropic polymer-bonded magnets or hot formed into fully dense magnets. This paper discusses the influence of heavy rare earth elements and microstructure on the magnetic performance, thermal stability and material cost of NdFeB magnets. Evidence indicates that melt-spun nanocrystalline NdFeB magnets are less dependent on heavy rare earth elements for high-temperature performance than the alternative coarser-grained sintered NdFeB magnets. In particular, hot-pressed melt-spun magnets are an attractive low-cost solution for applications that require thermal stability up to 175–200 °C.

J1640202 プラスチック基板上に規則配列した金属ナノドットアレイの効率的製造法 : 超微細切削加工による石英ガラス基板へ微細溝加工法の検討([J164-02]マイクロ・ナノ理工学:nmからmmまでの表面制御とその応用(2))

The authors are developing a manufacturing process of a metal nano dot array on a plastic substrate. In this paper, machining technology of a quartz glass substrate with fine groove array used for the process is studied. It is shown that a fine groove narrower than 300 run can be machined on a quartz glass plate by using a specially designed machining tester. It is also demonstrated that a fine groove array of a large area (1cm × 1cm) can be fabricated.

Estimation of HSQ Resist Profile by Using High Contrast Developement Model for High Resolution EB Lithography

We calculated thehydrogen silsesquioxane (HSQ) resistprofiles with different contrast developers (γ from 1.9 to 8.1) to reveal the effect of resist contrast on pattern resolution performance. Based on our home-made development modeling, the suitable energy deposition distribution (EDD) regions for various developers were determined by evaluating the quality of simulated patterns. High contrast TMAH 2.3 wt%/NaCl 4 wt% developer was demonstrated that it is suitable to form very fine dot arrays with a size of 7 nm. Low contrast developer has the limitation of forming fine pattern with sufficient height. The simulation results indicated that increasing developer contrast is benefit to improve pattern resolution.

Effect of Salty Development on Forming HSQ Resist Nanodot Arrays with a Pitch of 15×15 nm<sup>2</sup> by 30-keV Electron Beam Lithography

We investigated the effect of ultrahigh-resolution salty (NaCl contained) development of hydrogen silsesquioxane (HSQ) resist on forming fine dot arrays with a pitch of 15×15 nm2 by 30-keV electron beam lithography for patterned media. The optimized concentration of resist developers was determined to fabricate most packed pattern. We found that increasing the concentration of NaCl into tetramethyl ammonium hydroxide (TMAH) could greatly improve the resist contrast (γ-value) of HSQ. And by using 2.3 wt% TMAH/4 wt% NaCl developer, we demonstrated 15×15 nm2 pitched (3 Tbit/in.2) HSQ resist dot arrays with a dot size of < 10 nm.

Electron Beam Lithography of 15×15 nm2 Pitched Nanodot Arrays with a Size of Less than 10 nm Using High Development Contrast Salty Developer

We investigated the effects of developer and hydrogen silsesquioxane (HSQ) resist thickness in the formation of dot arrays with a pitch of <18×18 nm2 by using 30-keV electron beam (EB) lithography for bit patterned media (BPM). Optimum resist thickness and developer were investigated for the formation of fine dot arrays. We found that a 12-nm-thick HSQ resist was suitable to form fine dot patterns and the addition of NaCl into tetramethylammonium hydroxide (TMAH) could improve the development contrast (γ-value) of HSQ (the highest is 9.7). By using the 12-nm-thick HSQ resist film and 2.3 wt % TMAH/4 wt % NaCl developer, we successfully fabricated very fine resist dot arrays with a dot size of <10 nm and a pitch of 15×15 nm2, which corresponds to a storage density of about 3 Tbit/in.2 in BPM.

Investigation of Contact Behavior and Design of Vertical Probe for Wafer Level Probing

It is necessary to analyze the mechanism of bump wafer probing, for bump height variation and probe mark area significantly influence flip chip assembly reliability. This causes the development of an effective and reliable testing method which becomes more important as the testing method has to satisfy the requirements of fine pitch and area array bumps. Certainly the vertical probe card is a reliable solution to satisfy these requirements of bump wafer probing. In this paper, the mechanism of bump wafer probing is investigated and the relationships among tip-sphere contact force, overdrive, probe geometries, material properties, and scrub mark area are derived. This paper further investigates bump wafer probing criteria which compares the results of several contact models with the experimental results to avoid bump damage. In addition, a simple and accurate theoretical analysis is established for rapidly designing an appropriate probing system for bump wafer probing. Finally, the effects of vertical probes with various geometries on bump wafer probing are investigated.

Fabrication and adhesion of hierarchical micro-seta

Spark-erosion perforating technology was used to fabricate a Cu-based template characterized by pores with radius of 0.5 mm inclined at 75°. A commercial silicone elastomer of poly(dimethylsiloxane) (PDMS) with a rich Si-H content was used to produce an inclined array of primary setae. The technique of argon ion plasma etching on crystalline silicon was used to fabricate negative templates with radii of 5, 10, and 20 μm. The Si-H rich PDMS was used to cast three types of fine array templates, which acted as the secondary setae. A vinyl-rich PDMS precursor was used to bind the primary and secondary setae by a hydrosilylation reaction, thus allowing the formation of three different hierarchical arrangements of setae. Adhesion tests demonstrated that shear adhesion was anisotropic, first increasing in strength then decreasing to a stable level as slippage occurred. The adhesion strength was significantly influenced by the nature of the secondary setae, showing a strong correlation with aspect-ratio and concentration.

Electrochemical behavior of a lead-free SnAg solder alloy affected by the microstructure array

The aim of this study is to evaluate the electrochemical corrosion behavior of a Sn–Ag solder alloy in a 0.5 M NaCl solution at 25 °C as a function of microstructural characteristics. Different microstructure morphologies, which can be found in Sn–Ag solder joints and that are imposed by the local solidification cooling rate, are evaluated and correlated to the resulting scale of the dendritic matrix and the morphology of the Ag 3Sn intermetallic compound. Cylindrical metallic molds at two different initial temperatures were employed permitting the effect of 0.15 °C/s and 0.02 °C/s cooling rates on the microstructure pattern to be experimentally examined. Electrochemical impedance spectroscopy (EIS) diagrams, potentiodynamic polarization curves and an equivalent circuit analysis were used to evaluate the electrochemical parameters. It was found that higher cooling rates during solidification are associated with fine dendritic arrays and a mixture of spheroids and fiber-like Ag 3Sn particles which result in better corrosion resistance than coarse dendrite arrays associated with a mixture of fibers and plate-like Ag 3Sn morphologies which result from very slow cooling rates.

Representations: Doing Asian American Rhetoric (review)

Reviewed by: Representations: Doing Asian American Rhetoric Sue Hum Mao, LuMing, and Morris Young, eds. 2008. Representations: Doing Asian American Rhetoric. Logan: Utah State University Press. $29.95 sc. xv + 320 pp. An edited collection of fourteen original essays, Representations: Doing Asian American Rhetoric is divided into two major sections. The first provides a much-needed exercise in the discovery and recovery of Asian American voices within local contexts, and the second offers a fine array of challenges to the stereotypical representations of Asian Americans within popular discourses in the mass media. The collection—a valuable resource for scholars interested in Asian American rhetoric—expands the scholarly landscape, providing bibliographies on fiction, nonfiction, and scholarship by and about Asian Americans. Utilizing a cultural-rhetorical studies framework for analysis, all essays confront institutional racism and power-knowledge dynamics that privilege certain ways of knowing and speaking while marginalizing and suppressing others. Even though Asian American rhetoric is currently defined against dominant discourses, its practitioners have aimed to engender transformative meanings and effects within the larger American narrative through situated performances and contextualized discursive strategies. This collection characterizes such strategies as a "rhetoric of becoming," a generative rhetoric that is "always situated in particularizing situations and … always generates new meanings and significations at every discursive turn possible" (323). Editors LuMing Mao and Morris Young choose the singular "rhetoric" in the book title purposefully, seeking to capture within that term, despite the risks of essentialism, a "systematic, effective use and development by Asian Americans of symbolic resources" deployed in contexts that are "regularly imbued with highly asymmetrical relations of power" (3). The tensions and conflicts resulting from hegemonic power relations are most clearly and interestingly depicted in Haivan V.Hoang's elegant analysis of the use of racial slurs, such as John McCain's use of "gook" to refer to North Vietnamese soldiers, to reinscribe Asian Americans as perpetual foreigners and to ignore the historical processes of racial formation. Hoang proposes articulations of counter-memories as productive ways of responding to the racist discourses, as exemplified by Duc, a local university student belonging to the student [End Page 205] organization Vietnamese American Coalition (VAC). Seeking to promote a shared communal activism, Duc shows how the word "gook" encourages a "psychology of racism and racial violence," pointing to the hate crime murders of Vincent Chin and Thien Minh Ly. He also describes the range of responses to McCain's use of "gook," describing the internal conflicts within southern California's Little Saigon community and the VAC at a local university. Hoang argues that Duc's memorial retracing of the term "gook" represents one way of destabilizing the primacy of racism within a sign: "memory is a complex art that entails critically interpreting a sign's past and varied utterances, selectively weaving memorial compositions, and sharing cultural memories to foster social engagement" (81). Counter-memory matters in Asian American rhetoric because it provides a rich venue for participants to undermine hegemonic racial formations. Other performances of Asian American rhetoric across a variety of contexts are collected in section one, which also comprises a kind of sampler of rhetorics of race and ethnicity. Rory Ong examines three auto-documentaries, describing the challenges of avoiding essentialist portraits and the struggles in developing a transnational Asian American identity within the context of an American empire. Tomo Hattori and Stuart Ching argue against the use of the "between-worlds" trope within national, institutional, and disciplinary spaces because it alienates and excludes by freezing differences. Terese Guinsatao Monberg excavates the rhetorical legacy of Dorothy Laigo Cordova, the founder and executive director of the Filipino American National Historical Society, through an oral history methodology that prioritizes listening rather than seeing. Subhasree Chakravarty critiques North American Hindu nationalist movements that employ an aggressive, exclusivist rhetoric in their reproduction of past events and popular myths. Mira Chieko Shimabukuro recovers through archival research a "resistant ethos" in the response to Japanese mass incarceration during World War II. Robyn Tasaka explores how social location and class influence students' conceptions of themselves as Asian Americans in their autobiographical essays. Section two illustrates the multivalent tactics for confronting and transforming popular discourses, such as the myths of...

Function and morphology correlates of rectal nerve mechanoreceptors innervating the guinea pig internal anal sphincter

Mechanoreceptors to the internal anal sphincter (IAS) contribute to continence and normal defecation, yet relatively little is known about their function or morphology. We investigated the function and structure of mechanoreceptors to the guinea pig IAS. Extracellular recordings from rectal nerve branches to the IAS in vitro, combined with anterograde labeling of recorded nerve trunks, were used to characterize extrinsic afferent nerve endings activated by circumferential distension. Slowly adapting, stretch-sensitive afferents were recorded in rectal nerves to the IAS. Ten of 11 were silent under basal conditions and responded to circumferential stretch in a saturating linear manner. Rectal nerve afferents responded to compression with von Frey hairs with low thresholds (0.3-0.5 mN) and 3.4 ± 0.5 discrete, elongated mechanosensitive fields of innervation aligned parallel to circular muscle bundles (length = 62 ± 16 mm, n = 10). Anterogradely labeled rectal nerve axons typically passed through sparse irregular myenteric ganglia adjacent to the IAS, before ending in extensive varicose arrays within the circular muscle and, to a lesser extent, the longitudinal muscle overlying the IAS. Few (8%) IAS myenteric ganglia contained intraganglionic laminar endings. In eight preparations, mechanotransduction sites were mapped in combination with successful anterograde fills. Mechanotransduction sites were strongly associated with extensive fine varicose arrays within the circular muscle (P < 0.05), and not with any other neural structures. Mechanotransduction sites for low-threshold, slowly adapting mechanoreceptors innervating the IAS are likely to correspond to extensive fine varicose arrays within the circular muscle.

Possibility of Forming 18-nm-Pitch Ultrahigh Density Fine Dot Arrays for 2 Tbit/in.2 Patterned Media Using 30-keV Electron Beam Lithography

We studied the possibility of forming ultrahigh-density fine dot arrays using 30-keV electron beam (EB) drawing for 2 Tbit/in.2 patterned media. We investigated the effects of calixarene resist thickness and exposure dosage on the drawing of dot arrays with a minimum pitch. We found that the 13-nm-thick calixarene resist was very suitable for forming resist dot arrays with a pitch of 20 nm. Furthermore, the allowable region of proper exposure dosage became narrow as the pitch decreased. It is clarified that there exists a minimum pitch of 18 nm in drawing ultrahigh density fine dot arrays with a 13-nm-thick resist.

PROFESSOR MICHAEL WILLIAMS 1935–2009

PROFESSOR MICHAEL WILLIAMS 1935–2009

Study of Copper Residue Generated During Cu CMP Process

Copper (Cu) chemical-mechanical polishing (CMP) has been a critical technology for copper damascene manufacturing process for metal interconnects. This paper investigated the mechanism of the copper residue generated during Cu-CMP process. Both electrical testing and various physical measurement techniques have been extensively used for the characterization. For bulk Cu CMP process, the wear surface of the retaining ring caused reduction of the effective down pressure on the wafer, resulting in occurrence of residual copper. For barrier metal CMP process, the protrusion of the copper lines (negative oxide erosion) on the fine pitch line and space array was the main contributor to copper residue on the upper interconnection layer. This paper also examines the effects of slurry selectivity on topography correction and dielectric erosion, in multi-step Cu CMP processes. We proposed an optimal selectivity of Cu/Ta(tantalum)/SiO (0.6/1/0.8) of barrier metal polishing slurry to reduce copper residue between metal patterns and to ensure electrical isolation between neighboring circuit.

Dynamic rearrangement of F‐actin organization triggered by host‐specific plant signal is linked to morphogenesis of Aphanomyces cochlioides zoospores

Cochliophilin A (5-hydroxy-6,7-methylenedioxyflavone), a root releasing host-specific plant signal triggers chemotaxis and subsequent morphological changes in pathogenic Aphanomyces cochlioides zoospores before host penetration. The present study illustrates time-course changing patterns of cytoskeletal filamentous actin (F-actin) organization in the zoospores of A. cochlioides during rapid morphological changes (encystment and germination) after exposure to cochliophilin A. Confocal laser scanning microscopic analysis revealed that F-actin microfilaments remained concentrated at ventral groove and diffusely distributed in peripheral cytoplasm of the zoospore. These microfilaments dramatically rearranged and changed into granular F-actin plaques interconnected with fine arrays during encystment. A large patch of actin arrays accumulated at one pole of the cystospores just before germination. Then the actin plaques moved to the emerging germ tube where a distinct cap of microfilaments was seen at the tip of the emerging hypha. Zoospores treated with an inhibitor of F-actin polymerization, latrunculin B or motility halting and regeneration inducing compound nicotinamide, displayed different patterns of F-actin in both zoospores and cystospores than those obtained by the induction of cochliophilin A. Collectively, these results indicate that the host-specific plant signal cochliophilin A triggers a dynamic polymerization/depolymerization of F-actin in pathogenic A. cochlioides zoospores during early events of plant-peronosporomycete interactions.

Wear tests of steel knife blades

A study is presented on the relative wear rates of two carbon steels, a Damascus steel and a stainless steel, using the Cutlery and Allied Trades Research Association (CATRA) of Sheffield England cutting test machine. The carbon steels and stainless steel were heat treated to produce a fine array of carbides in a martensite matrix. Tests were done at hardness values of HRC = 41 and 61. At HRC = 61 the stainless steel had slightly superior cutting performance over the carbon steels, while at HRC = 41 the Damascus steel had slightly superior cutting performance.

Large-Scale, Reliable and Robust SERS-Active Nanowire Substrates Prepared Using Porous Alumina Templates

nanowire arrays for surface-enhanced Raman scattering applications. These nanowire films were synthesized via electrodeposition using porous alumina templates of varying order, thickness and pore diameters. Mechanical polishing has been shown to be a very effective method to prepare nanowire arrays with monodisperse length over comprehensively large dimensions. On the other hand, a convenient synthesis route has been suggested that allows the formation of nanoparticle rrays using very thin and/or large area porous alumina films. It is reckoned that even films with the smallest obtainable pore sizes can be utilized to prepare large area, fine nanoparticle arrays. Such arrays may also find use in other areas, such as solar cells and electrochemistry. Preliminary Raman experiments indicated that the nanowire/nanoparticle arrays are indeed surface-enhanced Raman scattering-active. Finally, the potentials offered by the reported processing methods for fabricating substrates with predictable and high Raman amplifications are discussed.

Head-neck domain of Arabidopsis myosin XI, MYA2, fused with GFP produces F-actin patterns that coincide with fast organelle streaming in different plant cells

BackgroundThe cytoskeletal mechanisms that underlie organelle transport in plants are intimately linked to acto-myosin function. This function is mediated by the attachment of myosin heads to F-actin and the binding of cargo to the tails. Acto-myosin also powers vigorous cytoplasmic streaming in plant cells. Class XI myosins exhibit strikingly fast velocities and may have extraordinary roles in cellular motility. Studies of the structural basis of organelle transport have focused on the cargo-binding tails of myosin XI, revealing a close relationship with the transport of peroxisomes, mitochondria, and Golgi-vesicles. Links between myosin heads and F-actin-based motility have been less investigated. To address this function, we performed localization studies using the head-neck domain of AtMYA2, a myosin XI from Arabidopsis.ResultsWe expressed the GFP-fused head-neck domain of MYA2 in epidermal cells of various plant species and found that it associated with F-actin. By comparison to other markers such as fimbrin and talin, we revealed that the myosin-labeled F-actin was of a lower quality and absent from the fine microfilament arrays at the cell cortex. However, it colocalized with cytoplasmic (transvacuolar) F-actin in areas coinciding with the tracks of fast organelles. This observation correlates well with the proposed function of myosin XI in organelle trafficking. The fact that organelle streaming was reduced in cells expressing the GFP-MYA2-head6IQ indicated that the functionless motor protein inhibits endogenous myosins. Furthermore, co-expression of the GFP-MYA2-head6IQ with other F-actin markers disrupted its attachment to F-actin. In nuclei, the GFP-myosin associated with short bundles of F-actin.ConclusionThe localization of the head of MYA2 in living plant cells, as investigated here for the first time, suggests a close linkage between this myosin XI and cytoplasmic microfilaments that support the rapid streaming of organelles such as peroxisomes. Potential roles of MYA2 may also exist in the cell nucleus. Whether the low quality of the F-actin-labeling by MYA2-head6IQ compared to other F-actin-binding proteins (ABPs) signifies a weak association of the myosin with actin filaments remains to be proven by other means than in vivo. Clues for the mode of contact between the myosin molecules and F-actin so far cannot be drawn from sequence-related data.

Advances in technologies for Wide Web Single Pass Printing with piezoelectric Inkjet

In the past it has been extremely difficult to attain the required quality and reliability needed to achieve a viable wide array single pass inkjet system to satisfy the needs of the printing industry for label and billing applications. However it is now practical to form such a system by utilizing a combination of several novel technologies.Printed inkjet quality has been achieved in the past by using a very fine pixel array requiring either a high nozzle density across the array or multi-passing techniques to fill in the gaps. The latter not being suitable for single pass applications, the industry has had to stack low nozzle density printheads to synthesize a higher density array. Unrestricted greyscale technology allows for images of apparent binary resolutions of about 1000 DPI to be created from medium resolution arrays. Shared Wall piezoelectric technology allows for the creation of such medium resolution arrays.Reliability is the other critical factor. In the past this has usually been achieved by redundancy or regular maintenance of the printhead to ensure that the nozzles remain primed with an intact meniscus. Again the latter option is not practical for a single pass printer but recirculating the ink at the nozzle (throughflow technology) effectively provides continuous maintenance of the meniscus irrespective of printed duty cycle and so allows for interrupt free operation.Incorporating shared wall operation, greyscale and the throughflow recirculation technologies together in a single printhead can give a physical nozzle density of 360 NPI an apparent binary resolution of nearly 1000 DPI when using 8 greylevels and be virtually maintenance free when printing.

Intratumor Genetic Heterogeneity of Breast Carcinomas as Determined by Fine Needle Aspiration and TaqMan Low Density Array

Background: Gene expression profiling is thought to be an important tool in determining treatment strategies for breast cancer patients. Tissues for such analysis may at a preoperative stage be obtained, by fine needle aspiration (FNA) allowing initiation of neoadjuvant treatment. To evaluate the extent of the genetic heterogeneity within primary breast carcinomas, we examined whether a gene expression profile obtained by FNA was representative of the tumor. Methods: Tumors from 12 consecutive cases of early predominantly estrogen receptor positive (ER+) breast cancer patients undergoing primary surgery were split in halves and FNAs were obtained from each half. A tissue biopsy of the tumors was also snap-frozen for comparison. Non-amplified RNA was investigated by the novel qRT-PCR-based technique, Low Density Array (LDA) using 4 reference genes and 44 target genes. Results: Comparison of gene expression at the single gene level in the two FNA samples from each tumor demonstrated various degrees of heterogeneity. However, compared as gene expression profiles, intratumor correlations for 9/12 patients were high and these pairs could in a theoretical blinding of all the FNAs be correctly matched by statistical analysis. High correlations between the gene profiles of tumor FNAs and tissue biopsies from the same patient were observed for all patients. A cluster analysis identified clustering of both the two FNAs and the tissue biopsy of the same 9 patients. Conclusion: The overall genetic heterogeneity of breast carcinomas, as sampled by FNA, does not prohibit generation of useful gene profiles for treatment decision making. However, sampling and analysis strategies should take heterogeneity within a tumor, and varying heterogeneity amongst the single genes, into account.

Possibility to form an ultrahigh packed fine pit and dot arrays for future storage using EB writing

Possibility of very fine bit arrays formation for an ultrahigh density optical and magnetic recordings has been researched using electron beam (EB) writing with a high resolution scanning electron microscope (SEM), a writing controller and positive and negative electron resists. As experimental results, calixarene negative EB resist is very suitable to form an ultrahigh packed bit arrays pattern. We obtained extremely fine dot arrays with a diameter of <15 nm, and both bit pitch (BP) and track pitch (TP) of <30 nm. The writing pattern promises to open trillion bits/in. 2 era.