bluuebunny/crossref_metadata_2025 huggingface dataset:
Predicting Behavioral Deficits in Pediatric Traumatic Brain Injury Through Uncinate Fasciculus Integrity
Authors: Johnson Chad P. , Juranek Jenifer , Kramer Larry A. , Prasad Mary R. , Swank Paul R. , Ewing-Cobbs Linda
Published: April 2011

Behavioral dysregulation is a common and detrimental consequence of traumatic brain injury (TBI) in children that contributes to poor academic achievement and deficits in social development. Unfortunately, behavioral dysregulation is difficult to predict from either injury severity or early neuropsychological evaluation. The uncinate fasciculus (UF) connects orbitofrontal and anterior temporal lobes, which are commonly implicated in emotional and behavioral regulation. Using probabilistic diffusion tensor tractography (DTT), we examined the relationship between the integrity of the UF 3 months post-injury and ratings of executive functions 12 months post-injury in children with moderate to severe TBI and a comparison group with orthopedic injuries. As expected, fractional anisotropy of the UF was lower in the TBI group relative to the orthopedic injury group. DTT metrics from the UF served as a biomarker and predicted ratings of emotional and behavior regulation, but not metacognition. In contrast, the Glasgow Coma Scale score was not related to either UF integrity or to executive function outcomes. Neuroanatomical biomarkers like the uncinate fasciculus may allow for early identification of behavioral problems and allow for investigation into the relationship of frontotemporal networks to brain-behavior relationships. (JINS, 2011, 17, 663–673)
RACE/ETHNICITY AND U.S. ADULT MORTALITY
Authors: Hummer Robert A. , Chinn Juanita J.
Published: April 2011

Although there have been significant decreases in U.S. mortality rates, racial/ethnic disparities persist. The goals of this study are to: (1) elucidate a conceptual framework for the study of racial/ethnic differences in U.S. adult mortality, (2) estimate current racial/ethnic differences in adult mortality, (3) examine empirically the extent to which measures of socioeconomic status and other risk factors impact the mortality differences across groups, and (4) utilize findings to inform the policy community with regard to eliminating racial/ethnic disparities in mortality. Relative Black-White differences are modestly narrower when compared to a decade or so ago, but remain very wide. The majority of the Black-White adult mortality gap can be accounted for by measures of socioeconomic resources that reflect the historical and continuing significance of racial socioeconomic stratification. Further, when controlling for socioeconomic resources, Mexican Americans and Mexican immigrants exhibit significantly lower mortality risk than non-Hispanic Whites. Without aggressive efforts to create equality in socioeconomic and social resources, Black-White disparities in mortality will remain wide, and mortality among the Mexican-origin population will remain higher than what would be the case if that population achieved socioeconomic equality with Whites.
RECONSIDERING KENNETH B. CLARK AND THE IDEA OF BLACK PSYCHOLOGICAL DAMAGE, 1931–1945
Authors: Freeman Damon
Published: April 2011

One of the most controversial figures in Black intellectual history is psychologist Kenneth B. Clark. Prominently identified as the main proponent of the idea that racial segregation led to psychological damage in Black children, Clark's work heavily influenced the U.S. Supreme Court in its 1954Brown v. Board of Educationschool desegregation decision. Almost immediately afterwards, his research methods and conclusions were challenged as incomplete and biased. Scholars now argue that Clark and other racial liberals became solely wedded to the idea of racial psychological damage in order to secure victory inBrown. Yet a closer analysis of his thought reveals a more complex picture. During the early 1940s, he developed a new psychological concept which he called the “zoot effect.” He defined the zoot effect as the attempt by a person to gain psychological security in a society which mandated that individual's inferiority. The zoot effect or zoot personality reflected the larger society's pathology, which manifested itself internally in individuals. This concept was heavily shaped by ideas about race, class, and in particular the work of Alfred Adler, which he first learned as a student at Howard University. Using archival and secondary sources, I argue for a reconceptualization of Clark within the broader context of his social thought, suggesting that the zoot-effect concept grounded his research on Black children and set the stage for his later views on desegregation, civil rights, and American society.
MEASURING EVERYDAY RACIAL/ETHNIC DISCRIMINATION IN HEALTH SURVEYS
Authors: Shariff-Marco Salma , Breen Nancy , Landrine Hope , Reeve Bryce B. , Krieger Nancy , Gee Gilbert C. , Williams David R. , Mays Vickie M. , Ponce Ninez A. , Alegría Margarita , Liu Benmei , Willis Gordon , Johnson Timothy P.
Published: April 2011

While it is clear that self-reported racial/ethnic discrimination is related to illness, there are challenges in measuring self-reported discrimination or unfair treatment. In the present study, we evaluate the psychometric properties of a self-reported instrument across racial/ethnic groups in a population-based sample, and we test and interpret findings from applying two different widely-used approaches to asking about discrimination and unfair treatment. Even though we found that the subset of items we tested tap into a single underlying concept, we also found that different groups are more likely to report on different aspects of discrimination. Whether race is mentioned in the survey question affects both frequency and mean scores of reports of racial/ethnic discrimination. Our findings suggest caution to researchers when comparing studies that have used different approaches to measure racial/ethnic discrimination and allow us to suggest practical empirical guidelines for measuring and analyzing racial/ethnic discrimination. No less important, we have developed a self-reported measure of recent racial/ethnic discrimination that functions well in a range of different racial/ethnic groups and makes it possible to compare how racial/ethnic discrimination is associated with health disparities among multiple racial/ethnic groups.
THE STRANGE DISAPPEARANCE OF HISTORY FROM RACIAL HEALTH DISPARITIES RESEARCH
Authors: Chowkwanyun Merlin
Published: April 2011

Although thriving in many respects, racial health disparities research suffers from a lack of historical analysis and may be in danger of reaching a saturation point. This article examines how renewed attention to history can enhance the explanatory power of such research. First, it surveys a body of writing on what history can contribute to contemporary social science and policy debates. Next, it compares current racial health disparities research to the analytical impasse encountered by urban poverty researchers of the late 1980s and early 1990s. It contrasts that work with two classic post-Second World War urban histories, and identifies qualities of the latter lacking in conventional social science. The essay then surveys historically oriented works on race and health, pointing out their usefulness to racial health disparities research while discussing promising future research directions. It concludes with a brief reflection on changes in the academic institutional context necessary for fruitful synergy between public health researchers and historians.
TOOTHLESS
Authors: Murakawa Naomi
Published: April 2011

From “reefer madness” to “crack babies,” American drug scares demonstrate that race shapes the construction of epidemics and diagnoses. This research brief reexamines the racial construction of drug scares in light of the recent methamphetamine (meth) scare, a drug “epidemic” constructed asWhiteand accompanied by a new diagnosis: “meth mouth.” Through examination of survey data and dental research, I challenge the evidence for both the “epidemic” upsurge in meth use and the “meth mouth” diagnosis. Given the weak evidentiary basis for epidemic and diagnosis, I offer a preliminary interpretation that the meth epidemic is constructed as symptom and cause of White status decline, with dental decay the vehicle for anxieties about descent into “White trash” status.
THE SUSTAINING RELEVANCE OF W. E. B. DU BOIS TO HEALTH DISPARITIES RESEARCH
Authors: White Kellee
Published: April 2011

William Edward Burghardt Du Bois is considered one of the most prolific and brilliant scholars of our time. While his contributions to civil rights, sociology, history, African American studies, and urban studies are universally recognized, his legacy in the public health and epidemiology discourses is not as widely acknowledged by contemporary health researchers. His seminal workThe Philadelphia Negro: A Social Study(1899) and his report “The Health and Physique of the Negro American” (1906) may be considered early harbingers in general of public health—and more specifically, social epidemiology—research. During the late nineteenth and early twentieth centuries, Black and White differences in mortality and morbidity were largely attributed to notions of biological racial inferiority. Efforts by Du Bois to challenge these predominant notions resulted in the systematic empirical investigation of social factors contributing to Black health risk and health disparities. More than one hundred years after Du Bois's pioneering scholarship, racial/ethnic and social disparities remain a central challenge for public health and medical professionals. Given the persistence of health disparities and the increasing focus on neighborhood social and physical environments as fundamental factors contributing to health inequalities, this paper seeks to historically situate Du Bois's scholarship, describe the methodological and conceptual significance of his seminal studies, and articulate the importance of incorporating Du Bois's legacy to advance the next generation of racial/ethnic health inequality research.
Arbeitsbedingte Prädiktoren für Zufriedenheit in der Demenzversorgung bei Pflegenden in stationären Altenpflegeeinrichtungen
Authors: Schmidt Sascha G. , Palm Rebecca , Dichter Martin , Hasselhorn Hans Martin
Published: April 2011

In stationären Altenpflegeeinrichtungen nimmt die Pflege von Bewohnern mit Demenz einen immer größeren Stellenwert ein. Gleichzeitig stellt die Pflege von Bewohnern mit Demenz einen Risikofaktor für eine Arbeitsbelastung bei Pflegenden selbst dar. In diesem Zusammenhang wurde die Assoziation von potenziellen arbeitbedingten Prädiktoren mit der «Zufriedenheit von Pflegenden mit der Pflege von Bewohnern mit Demenz» mittels Sekundärdatenanalyse von Daten aus der 3Q-Studie untersucht. Eingeschlossen wurden 813 Pflegende (Fachkräfte und Hilfskräfte) aus 53 stationären Altenpflegeeinrichtungen. 42% der Pflegenden waren unzufrieden, wobei größere Unterschiede zwischen den Einrichtungen zu finden waren. Fachkräfte und Pflegende in Leitungsfunktionen waren unzufriedener. Im multivariaten Regressionsmodell waren «quantitative Anforderungen», die «Führungsqualität» und «soziale Interaktion mit anderen Berufsgruppen» am stärksten mit Zufriedenheit mit der Pflege von Bewohnern mit Demenz assoziiert. Keine Assoziation wurde dagegen bei «emotionale Anforderungen» und «Entwicklungsmöglichkeiten» gefunden. Die Ergebnisse geben Hinweise darauf, dass die «Zufriedenheit von Pflegenden mit der Pflege von Bewohnern mit Demenz» ein wichtiger Aspekt bei der Arbeit von Pflegenden ist, welcher sowohl in der Praxis als auch in der Forschung größere Beachtung finden müsste. Die große prädiktive Stärke verschiedener Faktoren der Arbeitsorganisation weist darauf hin, dass präventive Ansätze zur Steigerung der Zufriedenheit speziell in diesem Bereich ansetzen sollten.
Symmetries in fluctuations far from equilibrium
Authors: Hurtado Pablo I. , Pérez-Espigares Carlos , del Pozo Jesús J. , Garrido Pedro L.
Published: April 2011

Fluctuations arise universally in nature as a reflection of the discrete microscopic world at the macroscopic level. Despite their apparent noisy origin, fluctuations encode fundamental aspects of the physics of the system at hand, crucial to understand irreversibility and nonequilibrium behavior. To sustain a given fluctuation, a system traverses a precise optimal path in phase space. Here we show that by demanding invariance of optimal paths under symmetry transformations, new and general fluctuation relations valid arbitrarily far from equilibrium are unveiled. This opens an unexplored route toward a deeper understanding of nonequilibrium physics by bringing symmetry principles to the realm of fluctuations. We illustrate this concept studying symmetries of the current distribution out of equilibrium. In particular we derive an isometric fluctuation relation that links in a strikingly simple manner the probabilities of any pair of isometric current fluctuations. This relation, which results from the time-reversibility of the dynamics, includes as a particular instance the Gallavotti–Cohen fluctuation theorem in this context but adds a completely new perspective on the high level of symmetry imposed by time-reversibility on the statistics of nonequilibrium fluctuations. The new symmetry implies remarkable hierarchies of equations for the current cumulants and the nonlinear response coefficients, going far beyond Onsager’s reciprocity relations and Green–Kubo formulas. We confirm the validity of the new symmetry relation in extensive numerical simulations, and suggest that the idea of symmetry in fluctuations as invariance of optimal paths has far-reaching consequences in diverse fields.
Control of energy and matter at nanoscales: challenges and opportunities for plasma nanoscience in a sustainability age
Authors: Ostrikov Kostya (Ken)
Published: April 2011

Plasma nanoscience is an emerging multidisciplinary research field at the cutting edge of a large number of disciplines including but not limited to physics and chemistry of plasmas and gas discharges, materials science, surface science, nanoscience and nanotechnology, solid-state physics, space physics and astrophysics, photonics, optics, plasmonics, spintronics, quantum information, physical chemistry, biomedical sciences and related engineering subjects. This paper examines the origin, progress and future perspectives of this research field driven by the global scientific and societal challenges. The future potential of plasma nanoscience to remain a highly topical area in the global research and technological agenda in the age of fundamental-level control for a sustainable future is assessed using a framework of the five Grand Challenges for Basic Energy Sciences recently mapped by the US Department of Energy. It is concluded that the ongoing research is very relevant and is expected to substantially expand to competitively contribute to the solution of all of these Grand Challenges. The approach to controlling energy and matter at nano- and subnanoscales is based on identifying the prevailing carriers and transfer mechanisms of the energy and matter at the spatial and temporal scales that are most relevant to any particular nanofabrication process. Strong accent is made on the competitive edge of the plasma-based nanotechnology in applications related to the major socio-economic issues (energy, food, water, health and environment) that are crucial for a sustainable development of humankind. Several important emerging topics, opportunities and multidisciplinary synergies for plasma nanoscience are highlighted. The main nanosafety issues are also discussed and the environment- and human health-friendly features of plasma-based nanotech are emphasized.
Plasma-synthesized single-walled carbon nanotubes and their applications
Authors: Hatakeyama R , Kaneko T , Kato T , Li Y F
Published: April 2011

Plasma-based nanotechnology is a rapidly developing area of research ranging from physics of gaseous and liquid plasmas to material science, surface science and nanofabrication. In our case, nanoscopic plasma processing is performed to grow single-walled carbon nanotubes (SWNTs) with controlled chirality distribution and to further develop SWNT-based materials with new functions corresponding to electronic and biomedical applications. Since SWNTs are furnished with hollow inner spaces, it is very interesting to inject various kinds of atoms and molecules into their nanospaces based on plasma nanotechnology. The encapsulation of alkali-metal atoms, halogen atoms, fullerene or azafullerene molecules inside the carbon nanotubes is realized using ionic plasmas of positive and negative ions such as alkali–fullerene, alkali–halogen, and pair or quasipair ion plasmas. Furthermore, an electrolyte solution plasma with DNA negative ions is prepared in order to encapsulate DNA molecules into the nanotubes. It is found that the electronic and optical properties of various encapsulated SWNTs are significantly changed compared with those of pristine ones. As a result, a number of interesting transport phenomena such as air-stable n- and p-type behaviour, p–n junction characteristic, and photoinduced electron transfer are observed. Finally, the creation of an emerging SWNTs-based nanobioelectronics system is challenged. Specifically, the bottom-up electric-field-assisted reactive ion etching is proposed to control the chirality of SWNTs, unexplored SWNT properties of magnetism and superconductivity are aimed at being pioneered, and innovative biomedical-nanoengineering with encapsulated SWNTs of higher-order structure are expected to be developed by applying advanced gas–liquid interfacial plasmas.
Atmospheric-pressure plasma synthesis of carbon nanotubes
Authors: Nozaki Tomohiro , Yoshida Shinpei , Karatsu Takuya , Okazaki Ken
Published: April 2011

An atmospheric-pressure radio-frequency discharge (APRFD) has great advantages over vacuum-oriented plasma-enhanced chemical vapour deposition (PECVD) as well as other types of atmospheric-pressure plasma sources in terms of single-walled carbon nanotube (SWCNT) growth. We first provide an overview on the recent advances in PECVD synthesis of CNTs, ranging from low pressure to atmospheric pressure, and then we present our current work focusing on the analysis of reactive species generated in the cathodic plasma sheath for further understanding of the SWCNT growth mechanism in PECVD. It was found that the plasma-generated C2H2 is the main CNT growth precursor in PECVD. Approximately 30% of the CH4 (initial feedstock) was converted into C2H6, C2H4 and C2H2. A trace amount of C2H2 enabled the synthesis of SWCNTs in the thermal chemical vapour deposition (CVD) regime. H2 is necessary to grow SWCNTs using PECVD because H2 suppresses the formation of excess amount of C2H2; however, H2 does not eliminate amorphous carbon even at H2/C2H2 ratios of 300. PECVD using a binary mixture of C2H2 and isotope-modified 13CH4 demonstrated that CH4 does not contribute to CNT growth in C2H2-assisted thermal CVD. Atmospheric-pressure PECVD performed with a He/CH4/H2 system is equivalent to C2H2-assisted thermal CVD without an etching gas. APRFD appears to produce a hidden species, which influences the CNT growth process.
Challenges in process integration of catalytic DC plasma synthesis of vertically aligned carbon nanofibres
Authors: Melechko Anatoli V , Pearce Ryan C , Hensley Dale K , Simpson Michael L , McKnight Timothy E
Published: April 2011

The ability to synthesize free-standing, individual carbon nanofibres (CNFs) aligned perpendicularly to a substrate has enabled fabrication of a large array of devices with nanoscale functional elements, including electron field emission sources, electrochemical probes, neural interface arrays, scanning probes, gene delivery arrays and many others. This was made possible by development of a catalytic plasma process, with DC bias directing the alignment of nanofibres. Successful implementation of prototypical devices has uncovered numerous challenges in the integration of this synthesis process as one of the steps in device fabrication. This paper is dedicated to these engineering and fundamental difficulties that hinder further device development. Relatively high temperature for catalytic synthesis, electrical conductivity of the substrate to maintain DC discharge and other difficulties place restrictions on substrate material. Balancing non-catalytic carbon film deposition and substrate etching, non-uniformity of plasma due to growth of the high aspect ratio structures, plasma instabilities and other factors lead to challenges in controlling the plasma. Ultimately, controlling the atomistic processes at the catalyst nanoparticle (NP) and the behaviour of the NP is the central challenge of plasma nanosynthesis of vertically aligned CNFs.
Plasma production of nanodevice-grade semiconductor nanocrystals
Authors: Holman Z C , Kortshagen U R
Published: April 2011

Semiconductor nanocrystals (NCs) offer new opportunities for optical and electronic devices ranging from single-electron transistors to large-area solar cells. Solution synthesis methods cannot reach the temperatures necessary to produce crystalline nanoparticles of covalently bonded materials, and most gas-phase techniques suffer from particle agglomeration and sintering. Nonthermal plasma synthesis, however, can produce high-quality NCs of key materials such as Si and Ge. In this review, we examine the current state and future challenges of the growing field of plasma-synthesized NCs from a device applications perspective. We identify NC microstructure, morphology, ensemble monodispersity, surface chemistry and doping as being vital to the success of next-generation devices, and we discuss research opportunities to understand and control these properties during plasma synthesis.
Relating plasma processing, surface morphology, and electronic properties of nanomaterials
Authors: Ligatchev Valeri
Published: April 2011

Current approaches for analysis of the interrelations among plasma processing, morphological characteristics, electronic and optical properties of nano-structured materials are reviewed briefly. Practical implementation of these approaches is demonstrated for the cases of the plasma-assisted formation of silicon–germanium (Si1−x
Ge
x
, 0 ⩽ x ⩽ 1.0) nano-structures on Si substrates with different crystalline orientations. Both numerical simulations and experimental studies on the effects of plasma parameters, germanium concentration, boron doping, crystalline orientations of the substrate on low-temperature photoluminescence (PL) of the Si1−x
Ge
x
structures are considered. Different mechanisms of Si1−x
Ge
x
morphology formation (e.g. traditional Stranski–Krastanov route as well as new approaches like cluster fluxes created in the plasmas) are compared; the latter ones are more flexible and exhibit wider range of the potential applications. Furthermore, effects of morphological characteristics and phonon confinement as well as energetic characteristics of the optic and acoustic phonons on the PL and electronic parameters of the experimentally studied nano-structures are analysed within the generalized Skettrup model and ‘displaced oscillator’ approximation.
Plasma-enhanced chemical vapour deposition of inorganic nanomaterials using a chloride precursor
Authors: Yang Rong , Zheng Jie , Li Wei , Qu Jianglan , Li Xingguo
Published: April 2011

Plasmas have been widely used for the fabrication of nanomaterials owing to their unique properties in chemical reactions. The plasma-enhanced chemical vapour deposition (PECVD) technique has been applied to produce a large variety of materials. In this perspective, we take a look at the progress made in the research of PECVD using chloride precursors in the last decade. We discuss the advantage of using a plasma compared with the thermal chemical vapour deposition technique and emphasize the special effects of plasma on nanomaterial fabrications in the PECVD technique, including kinetic and thermodynamic effects. We also outline the current challenges for this technique, and attempt to offer our personal opinion on the future applications of the PECVD technique with chloride precursors.
Supported plasma-made 1D heterostructures: perspectives and applications
Authors: Borras Ana , Macias-Montero Manuel , Romero-Gomez Pablo , Gonzalez-Elipe Agustin R
Published: April 2011

Plasma-related methods have been widely used in the fabrication of carbon nanotubes and nanofibres (NFs) and semiconducting inorganic nanowires (NWs). A natural progression of the research in the field of 1D nanostructures is the synthesis of multicomponent NWs and NFs. In this paper we review the state of the art of the fabrication by plasma methods of 1D heterostructures including applications and perspectives. Furthermore, recent developments on the use of metal seeds (Ag, Au, Pt) to obtain metal@oxide nanostructures are also extensively described. Results are shown for various metal substrates, either metal foils or supported nanoparticles/thin films of the metal where the effects of the size, surface coverage, percolation degree and thickness of the metal seeds have been systematically evaluated. The possibilities of the process are illustrated by the preparation of nanostructured films and supported NFs of different metal@oxides (Ag, Au and SiO2, TiO2, ZnO). Particularly, in the case of silver, the application of an oxygen plasma treatment prior to the deposition of the oxide was critical for efficiently controlling the growth of the 1D heterostructures. A phenomenological model is proposed to account for the thin-film nanostructuring and fibre formation by considering basic phenomena such as stress relaxation, inhomogeneities in the plasma sheath electrical field and the local disturbance of the oxide growth.
Applications and challenges of plasma processes in nanobiotechnology
Authors: Rossi F , Colpo P
Published: April 2011

We present an overview of the possibilities offered by plasma technologies, in particular the combination plasma polymers deposition, colloidal lithography, e-beam lithography and microcontact printing, to produce micro- and nanostructured surfaces with chemical and topographical contrast for applications in nanobiotechnology. It is shown that chemical and topographical patterns can be obtained on different substrates, with dimensions down to a few tenths of 10 nm. The applications of these nanostructured surfaces in biology, biochemistry and biodetection are presented and the advantages and limitation of the plasma techniques in this context underlined.
Plasma nanofabrication and nanomaterials safety
Authors: Han Z J , Levchenko I , Kumar S , Yajadda M M A , Yick S , Seo D H , Martin P J , Peel S , Kuncic Z , Ostrikov K
Published: April 2011

The fast advances in nanotechnology have raised increasing concerns related to the safety of nanomaterials when exposed to humans, animals and the environment. However, despite several years of research, the nanomaterials safety field is still in its infancy owing to the complexities of structural and surface properties of these nanomaterials and organism-specific responses to them. Recently, plasma-based technology has been demonstrated as a versatile and effective way for nanofabrication, yet its health and environment-benign nature has not been widely recognized. Here we address the environmental and occupational health and safety effects of various zero- and one-dimensional nanomaterials and elaborate the advantages of using plasmas as a safe nanofabrication tool. These advantages include but are not limited to the production of substrate-bound nanomaterials, the isolation of humans from harmful nanomaterials, and the effective reforming of toxic and flammable gases. It is concluded that plasma nanofabrication can minimize the hazards in the workplace and represents a safe way for future nanofabrication technologies.
Self-organization in arrays of surface-grown nanoparticles: characterization, control, driving forces
Authors: Levchenko I , Kumar S , Yajadda M M A , Han Z J , Furman S , Ostrikov K
Published: April 2011

Some important issues related to the self-organization in the arrays of nanoparticles on solid surfaces exposed to the low-temperature plasma are analysed and discussed. The available tools for the characterization of the size and position uniformity in nanoarrays are examined. The technique capable of revealing the realistic adsorbed atom and adsorbed radical capture zone pattern based on the surface physics is indicated as the most promising characterization tool. The processes responsible for the self-organization are analysed, the main driving forces of the self-organization are discussed, and possible ways to control the self-organization by controlling the plasma parameters are introduced. A view on the possible ways to further improve the methods of nanoarray characterization and self-organization is presented as well.
Controlling roughness: from etching to nanotexturing and plasma-directed organization on organic and inorganic materials
Authors: Gogolides Evangelos , Constantoudis Vassilios , Kokkoris George , Kontziampasis Dimitrios , Tsougeni Katerina , Boulousis George , Vlachopoulou Marilena , Tserepi Angeliki
Published: April 2011

We describe how plasma–wall interactions in etching plasmas lead to either random roughening/nanotexturing of polymeric and silicon surfaces, or formation of organized nanostructures on such surfaces. We conduct carefully designed experiments of plasma–wall interactions to understand the causes of both phenomena, and present Monte Carlo simulation results confirming the experiments. We discuss emerging applications in wetting and optical property control, protein immobilisation, microfluidics and lab-on-a-chip fabrication and modification, and cost-effective silicon mould fabrication. We conclude with an outlook on the plasma reactor future designs to take advantage of the observed phenomena for new micro- and nanomanufacturing processes, and new contributions to plasma nanoassembly.
Perspectives on atmospheric-pressure plasmas for nanofabrication
Authors: Mariotti Davide , Sankaran R Mohan
Published: April 2011

Low-pressure, low-temperature plasmas are widely used for materials applications in industries ranging from electronics to medicine. To avoid the high costs associated with vacuum equipment, there has always been a strong motivation to operate plasmas at higher pressures, up to atmospheric. However, high-pressure operation of plasmas often leads to instabilities and gas heating, conditions that are unsuitable for materials applications. The recent development of microscale plasmas (i.e. microplasmas) has helped realize the sustainment of stable, non-thermal plasmas at atmospheric pressure and enable low-cost materials applications. There has also been an unexpected benefit of atmospheric-pressure operation: the potential to fabricate nanoscale materials which is not possible by more conventional, low-pressure plasmas. For example, in a high-pressure environment, nanoparticles can be nucleated in the gas phase from vapour (or solid metal) precursors. Alternatively, non-thermal, atmospheric-pressure plasmas can be coupled with liquids such as water or ethanol to nucleate and modify solution-phase nanoparticles. In this perspective paper, we review some of these recent efforts and provide an outlook for the rapidly emerging field of atmospheric-pressure plasmas for nanofabrication.
Nanomaterials synthesis at atmospheric pressure using nanosecond discharges
Authors: Pai David Z
Published: April 2011

The application of nanosecond discharges towards nanomaterials synthesis at atmospheric pressure is explored in this perspective article. First, various plasma sources are evaluated in terms of the energy used to include one atom into the nanomaterial, which is shown to depend strongly on the electron temperature. Because of their high average electron temperature, nanosecond discharges could be used to achieve nanofabrication at a lower energy cost, and therefore with better efficiency, than with other plasma sources at atmospheric pressure. Transient spark discharges and nanosecond repetitively pulsed (NRP) discharges are suggested as particularly useful examples of nanosecond discharges generated at high repetition frequency. Nanosecond discharges also generate fast heating and cooling rates that could be exploited to produce metastable nanomaterials.
High-energy density beams and plasmas for micro- and nano-texturing of surfaces by rapid melting and solidification
Authors: Surla Vijay , Ruzic David
Published: April 2011

Several advances in materials research have been made due to the wide array of tools currently available for the processing of materials: plasmas, electron beams, ion beams and lasers. The area of material science is fortunate to have seen the development of these tools over the years, be it for new bulk materials, coatings or for surface modification. Several applications have benefited and many more will in the future as the properties of the materials are altered on a micro/nanoscale. Currently, several techniques exist to modify the physical, chemical and biological properties of the material surface; however, this review limits itself to surface modification applications using the rapid thermal processing (RTP) technique. First, a brief overview of the existing surface modification methods using the principles of RTP is reviewed, and then a novel method to create micro/nanostructures on the surface using pulsed plasma exposure of materials is presented.
Extremely non-equilibrium oxygen plasma for direct synthesis of metal oxide nanowires on metallic substrates
Authors: Mozetic Miran
Published: April 2011

A promising method for the synthesis of metal oxide nanowires is based on the application of the extremely non-equilibrium gaseous environment found in oxygen plasma created by some types of discharges. The kinetic temperature of neutral gas is kept close to the room temperature, the electron temperature is a few eV, the ionization fraction below 10−6 and the dissociation fraction close to 100%. Plasma with such characteristics is obtained using electrodeless high frequency discharges driven by radiofrequency or microwave generators. Plasma parameters such as the electron density and energy distribution function, the Debye length, the dissociation and ionization fractions, the density of negatively charged molecules, the ratio between the positively charged molecules and atoms and the distribution of atoms and molecules over excited states depend on discharge parameters. The most important discharge parameters are the generator power, frequency and coupling, the purity and pressure of working gas and the gas flow, the dimensions of the discharge chamber, the materials facing plasma, the residual atmosphere, and, usually very importantly though often neglected, the properties of the samples mounted into a discharge chamber. Proper construction of the experimental system for the synthesis of metal oxide nanowires allows for almost 100% dissociation fraction and thus extremely rapid growing of nanowires. The particularities of oxygen plasma as well as real-time monitoring of the dissociation fraction are elaborated in this contribution. The lack of reliable experimental results on characterization of extremely non-equilibrium oxygen plasma is stressed.
On the heating of nano- and microparticles in process plasmas
Authors: Maurer H R , Kersten H
Published: April 2011

Determination and understanding of energy fluxes to nano- or microparticles, which are confined in process plasmas, is highly desirable because the energy balance results in an equilibrium particle temperature which may even initiate the crystallization of nanoparticles. A simple balance model has been used to estimate the energy fluxes between plasma and immersed particles on the basis of measured plasma parameters. Addition of molecular hydrogen to the argon plasma results in additional heating of the particles due to molecule recombination. The measured particle temperature is discussed with respect to appearing plasma–particle interactions which contribute to the particle's energy balance.
Formation of vertically aligned carbon nanostructures in plasmas: numerical modelling of growth and energy exchange
Authors: Denysenko I , Azarenkov N A
Published: April 2011

Results on modelling of the plasma-assisted growth of vertically aligned carbon nanostructures and of the energy exchange between the plasma and the growing nanostructures are reviewed. Growth of carbon nanofibres and single-walled carbon nanotubes is considered. Focus is made on studies that use the models based on mass balance equations for species, which are adsorbed on catalyst nanoparticles or walls of the nanostructures. It is shown that the models can be effectively used for the study and optimization of nanostructure growth in plasma-enhanced chemical vapour deposition. The results from these models are in good agreement with the available experimental data on the growth of nanostructures. It is discussed how input parameters for the models may be obtained.
Inorganic nanowires: a perspective about their role in energy conversion and storage applications
Authors: Sunkara M K , Pendyala C , Cummins D , Meduri P , Jasinski J , Kumar V , Russell H B , Clark E L , Kim J H
Published: April 2011

There has been tremendous interest and progress with synthesis of inorganic nanowires (NWs). However, much of the progress only resulted in NWs with diameters much greater than their respective quantum confinement scales, i.e. 10–100 nm. Even at this scale, NW-based materials offer enhanced charge transport and smaller diffusion length scales for improved performance with various electrochemical and photoelectrochemical energy conversion and storage applications. In this paper, these improvements are illustrated with specific results on enhanced charge transport with tin oxide NWs in dye sensitized solar cells, higher capacity retention with molybdenum oxide (MoO3) NW arrays and enhanced photoactivity with hematite NW arrays compared with their nanoparticle (NP) or thin film format counterparts. In addition, the NWs or one-dimensional crystalline materials with diameters less than 100 nm provide a useful platform for creating new materials either as substrates for heteroepitaxy or through the phase transformation with reaction. Specific results with single crystal phase transformation of hematite (a-Fe2O3) to pyrite (FeS2) NWs and heteroepitaxy of indium-rich InGaN alloy over GaN NW substrates are presented to illustrate the viability of using NWs for creating new materials. In terms of energy applications, it is essential to have a method for continuous manufacturing of vertical NW arrays over large areas. In this regard, a simple plasma-based technique is discussed that potentially could be scaled up for roll-to-roll processing of NW arrays.
Plasma-aided fabrication in Si-based photovoltaic applications: an overview
Authors: Xiao S Q , Xu S
Published: April 2011

Plasma-aided fabrication has been largely employed in the photovoltaic industry and widely reported in the literature for the growth of Si-based solar cells and the dry etching of Si substrates. This paper reviews the current status of plasma technologies for the synthesis of Si-based thin films (including silicon nitride: SiN) and solar cells, removal of phosphorus silicate glass or parasitic emitters, wafer cleaning, masked or mask-free surface texturization and the direct formation of a p–n junction by means of p-to-n type conductivity conversion. The plasma physics and chemistry involved in these processes and their fundamental mechanisms are briefly discussed. Some examples of superior performance and competitive advantages of plasma processes and techniques are selected to represent a range of applications for solar cells. Finally, an outlook in the field of plasma-aided fabrication for photovoltaic applications is given.
Plasma synthesis of nanostructures for improved thermoelectric properties
Authors: Petermann Nils , Stein Niklas , Schierning Gabi , Theissmann Ralf , Stoib Benedikt , Brandt Martin S , Hecht Christian , Schulz Christof , Wiggers Hartmut
Published: April 2011

The utilization of silicon-based materials for thermoelectrics is studied with respect to the synthesis and processing of doped silicon nanoparticles from gas phase plasma synthesis. It is found that plasma synthesis enables the formation of spherical, highly crystalline and soft-agglomerated materials. We discuss the requirements for the formation of dense sintered bodies, while keeping the crystallite size small. Small particles a few tens of nanometres and below that are easily achievable from plasma synthesis, and a weak surface oxidation, both lead to a pronounced sinter activity about 350 K below the temperature usually needed for the successful densification of silicon. The thermoelectric properties of our sintered materials are comparable to the best results found for nanocrystalline silicon prepared by methods other than plasma synthesis.
BamTools: a C++ API and toolkit for analyzing and managing BAM files
Authors: Barnett Derek W. , Garrison Erik K. , Quinlan Aaron R. , Strömberg Michael P. , Marth Gabor T.
Published: April 2011

Motivation: Analysis of genomic sequencing data requires efficient, easy-to-use access to alignment results and flexible data management tools (e.g. filtering, merging, sorting, etc.). However, the enormous amount of data produced by current sequencing technologies is typically stored in compressed, binary formats that are not easily handled by the text-based parsers commonly used in bioinformatics research.

Results: We introduce a software suite for programmers and end users that facilitates research analysis and data management using BAM files. BamTools provides both the first C++ API publicly available for BAM file support as well as a command-line toolkit.

Availability: BamTools was written in C++, and is supported on Linux, Mac OSX and MS Windows. Source code and documentation are freely available at http://github.org/pezmaster31/bamtools.

Contact:  barnetde@bc.edu
‘Sciencenet’—towards a global search and share engine for all scientific knowledge
Authors: Lütjohann Dominic S. , Shah Asmi H. , Christen Michael P. , Richter Florian , Knese Karsten , Liebel Urban
Published: April 2011

Summary: Modern biological experiments create vast amounts of data which are geographically distributed. These datasets consist of petabytes of raw data and billions of documents. Yet to the best of our knowledge, a search engine technology that searches and cross-links all different data types in life sciences does not exist.

We have developed a prototype distributed scientific search engine technology, ‘Sciencenet’, which facilitates rapid searching over this large data space. By ‘bringing the search engine to the data’, we do not require server farms. This platform also allows users to contribute to the search index and publish their large-scale data to support e-Science. Furthermore, a community-driven method guarantees that only scientific content is crawled and presented. Our peer-to-peer approach is sufficiently scalable for the science web without performance or capacity tradeoff.

Availability and Implementation: The free to use search portal web page and the downloadable client are accessible at: http://sciencenet.kit.edu. The web portal for index administration is implemented in ASP.NET, the ‘AskMe’ experiment publisher is written in Python 2.7, and the backend ‘YaCy’ search engine is based on Java 1.6.

Contact:  urban.liebel@kit.edu

Supplementary Material: Detailed instructions and descriptions can be found on the project homepage: http://sciencenet.kit.edu.
SMETHILLIUM: spatial normalization METHod for ILLumina InfinIUM HumanMethylation BeadChip
Authors: Sabbah Camille , Mazo Gildas , Paccard Caroline , Reyal Fabien , Hupé Philippe
Published: April 2011

Summary: DNA methylation is a major epigenetic modification in human cells. Illumina HumanMethylation27 BeadChip makes it possible to quantify the methylation state of 27 578 loci spanning 14 495 genes. We developed a non-parametric normalization method to correct the spatial background noise in order to improve the signal-to-noise ratio. The prediction performance of the proposed method was assessed on three fully methylated samples and three fully unmethylated DNA samples. We demonstrate that the spatial normalization outperforms BeadStudio to predict the methylation state of a given locus.

Availability and Implementation: A R script and the data are available at the following address: http://bioinfo.curie.fr/projects/smethillium.

Contact:  smethillium@curie.fr

Supplementary information:  Supplementary data are available at Bioinformatics online.
Figure summarizer browser extensions for PubMed Central
Authors: Agarwal Shashank , Yu Hong
Published: April 2011

Summary: Figures in biomedical articles present visual evidence for research facts and help readers understand the article better. However, when figures are taken out of context, it is difficult to understand their content. We developed a summarization algorithm to summarize the content of figures and used it in our figure search engine (http://figuresearch.askhermes.org/). In this article, we report on the development of web browser extensions for Mozilla Firefox, Google Chrome and Apple Safari to display summaries for figures in PubMed Central and NCBI Images.

Availability: The extensions can be downloaded from http://figuresearch.askhermes.org/articlesearch/extensions.php.

Contact:  agarwal@uwm.edu
Implications of a warming eastern Bering Sea for Bristol Bay sockeye salmon
Authors: Farley Edward V. , Starovoytov Alexander , Naydenko Svetlana , Heintz Ron , Trudel Marc , Guthrie Charles , Eisner Lisa , Guyon Jeffrey R.
Published: April 2011

Farley, E. V., Starovoytov, A., Naydenko, S., Heintz, R., Trudel, M., Guthrie, C., Eisner, L., Guyon, J. R. 2011. Implications of a warming eastern Bering Sea for Bristol Bay sockeye salmon. – ICES Journal of Marine Science, 68: 1138–1146. Overwinter survival of Pacific salmon (Oncorhynchus sp.) is believed to be a function of size and energetic status they gain during their first summer at sea. We test this notion for Bristol Bay sockeye salmon (O. nerka), utilizing data from large-scale fisheries and oceanographic surveys conducted during mid-August to September 2002–2008 and from February to March 2009. The new data presented in this paper demonstrate size-selective mortality for Bristol Bay sockeye salmon between autumn and their first winter at sea. Differences in the seasonal energetic signatures for lipid and protein suggest that these fish are not starving, but instead the larger fish caught during winter apparently are utilizing energy stores to minimize predation. Energetic status of juvenile sockeye salmon was also strongly related to marine survival indices and years with lower energetic status apparently are a function of density-dependent processes associated with high abundance of juvenile sockeye salmon. Based on new information regarding eastern Bering Sea ecosystem productivity under a climate-warming scenario, we hypothesize that sustained increases in spring and summer sea temperatures may negatively affect energetic status of juvenile sockeye salmon, potentially resulting in increased overwinter mortality.