bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectroscopy of single‐walled carbon nanotubes in aqueous surfactant dispersion
Authors: Movia Dania , Del Canto Elisa , Giordani Silvia 
Published: October 2009

AbstractOptical studies of single‐walled carbon nanotubes (SWNTs) dispersed in aqueous surfactant suspensions have made significant progress since the discovery of their bright band‐gap fluorescence in the near‐infrared region [M. J. O'Connell et al., Science 297, 593–596 (2002)]. In this article we report the systematic investigation of the effect of chemical purification and oxidation on the spectroscopic properties of SWNTs. The SWNTs samples we prepared differ for the percentage of impurities present, the amount of defects introduced in their graphitic structure and/or the functional groups expressed on their surface. The generation of carboxylic groups on the nanotubes surface by oxidative treatment was validated by means of thermal gravimetric analysis and ATR/Fourier transform IR spectroscopies, as well as Raman spectroscopy. We have solubilized pristine, purified SWNTs (p‐SWNTs) and oxidized SWNTs (o‐SWNTS) in Milli‐Q water using sodium dodecylbenzene sulphonate (SDBS). While our Vis‐NIR Absorption spectra of p‐SWNTs and o‐SWNTS dispersions in aqueous SDBS solution show the loss of the resolution of the characteristic van Hove singularities, NIR Photoluminescence spectra are characterized by structured emission peaks.
Characterization of dye molecules and carbon nanostructures by tip‐enhanced Raman spectroscopy
Authors: Peica Niculina , Röhrig Serge , Rüdiger Andreas , Brose Katharina , Thomsen Christian , Maultzsch Janina 
Published: October 2009

AbstractTip‐enhanced Raman spectroscopy (TERS) is a high sensitivity and high spatial resolution analytical technique based on the strong field enhancement provided by a sharp metallic tip. Using a commercial atomic force microscope (AFM) combined with a confocal optical setup in reflection geometry, we are targeting samples on non‐transparent electrodes. The resulting design challenges with respect to quantum efficiency, optical accessibility of the tip and the optics themselves, were balanced and taken into consideration for the presented ultra‐high vacuum–TERS setup. Second, we describe the development of a TERS setup at normal pressure in air, and we present the confocal Raman and TERS spectra of dye molecules and other nanostructures.
Development of graphene layers by reduction of graphite fluoride C2F surface
Authors: Okotrub A. V. , Asanov I. P. , Yudanov N. F. , Babin K. S , Gusel'nikov A. V. , Nedoseikina T. I. , Gevko P. N. , Bulusheva L. G. , Osváth Z. , Biró L. P. 
Published: October 2009

AbstractWe studied a possibility of reduction of the surface of graphite fluoride obtained by fluorination of highly oriented pyrolytic graphite (HOPG) by a gaseous mixture of BrF3 and Br2. X‐ray diffraction (XRD) revealed a layered structure of the fluorinated product being a second‐stage intercalate due to a presence of bromine molecules between the fluorinated graphite layers. Scanning tunneling microscopy and spectroscopy showed that the “old” surface of graphite fluoride (exposed to the ambient air) has the graphite‐like structure, while the fresh cleaved surface is non‐conductive. Therefore, the outer layers of graphite fluoride can be reduced by water present in the laboratory atmosphere. The sample was treated by H2O vapor to confirm that. The reduction was controlled by Raman spectroscopy using intensity of the 1360 and 1580 cm−1 bands. The energy dependent photoelectron spectroscopy was used for estimation of thickness of the reduction layer, which was found, does not exceed 2–3 graphite layers. The obtained results indicate the possibility of synthesis of graphene layers on dielectric fluorinated graphite matrix.
Microstructural study of He‐implanted Fe‐Cr alloys with the use of conventional lifetime technique and pulsed low energy positron beam
Authors: Kršjak Vladimír , Slugen Vladimír , Petriska Martin , Sojak Stanislav , Egger Werner 
Published: October 2009

AbstractExperimental simulation of the radiation damage using He+ implantation has been performed in research of Fe‐Cr model alloys. Different chromium content in the studied materials enables investigations of the effect of this element on the microstructure of radiation treated materials. The damaged region was investigated with the positron lifetime techniques with focus on the size and distribution of the defects. Our measurements show that not only pulsed low energy positron beam spectroscopy (PLEPS) but also conventional lifetime spectroscopy can study the behaviour of vacancy type defects induced by implantation of charged particles. Our results show that initial microstructure of low Cr alloys with significant presence of vacancy type defects is less resistant to creation of defect agglomeration in comparison with higher Cr alloys. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microstructural study of high irradiated reactor steels
Authors: Slugen Vladimír , Kršjak Vladimír , Petriska Martin , Sojak Stanislav , Veterníková Jana 
Published: October 2009

AbstractPositron Annihilation Spectroscopy (PAS) techniques in combination with other techniques were effectively used in the testing and selection process of optimal reactor steels for use in Generation III and IV reactors or thermonuclear fusion facilities. Conventional PAS lifetime technique and pulsed low energy positron system were applied on wide spectrum of reactor steels together with other techniques viz., Transmis sion Electron Microscopy and Mossbauer Spectroscopy focused on the role of Nickel in the steel microstructure. Experimental experiences in this area collected over the last twenty years were very useful in the actual study by avoiding many mistakes in handling with specimens or in careful interpretation of the results. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A mini linac based positron source
Authors: Pérez Patrice , Liszkay Laszlo , Rey Jean‐Michel , Blideanu Valentin , Carty Mickael , Curtoni Aline , Delferrierre Olivier , Dupré Pierre , Muranaka Tomoko , Ruiz Nicolas , Sacquin Yves 
Published: October 2009

AbstractWe have installed in Saclay a demonstration setup for an intense positron source in November 2008. It is based on a compact 6 MeV electron linac to produce positrons via pair production on a tungsten target. A relatively high current of 0.15 mA compensates the low energy, which is below the neutron activation threshold. The expected production rate is 4x1011 fast positrons per second. A set of coils is arranged to select the fast positrons from the diffracted electron beam in order to study the possibility to use a rare gas cryogenic moderator away from the main flux of particles. A first part of the commissioning of the linac has been performed. First attempts at measuring the fast positron flux are underway. This setup is part of a project to demonstrate the feasibility of an experiment to produce the H+ ion for a free fall measurement of neutral antihydrogen (H). Its small size and cost could be of interest for a university laboratory or industry for materials science applications. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recent development of the PAES set up at NEPOMUC
Authors: Mayer J. , Schreckenbach K. , Hugenschmidt C. 
Published: October 2009

AbstractPositron annihilation induced Auger electron spectroscopy (PAES) enables background free, non destructive surface analysis. Until now the long measurement time of up to several days restricted the area of application. In this paper the new set up at the reactor based positron source NEPOMUC is presented as well as first measurements with a new, efficient electron energy analyzer. For the first time, overview Auger spectra are now available in less than 15 minutes. Furthermore the high energy resolution of the PAES system is presented with the resolution of the copper M2,3VV double peak using PAES (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mn doping in ZnO nanoparticles: effects investigated by positron lifetime and Doppler broadening studies
Authors: Roy B. , Karmakar B. , Pal M. , Nambissan P. M. G. 
Published: October 2009

AbstractPositron lifetime and Doppler broadening measurements in nanocrystalline zinc oxide (ZnO) indicated the negatively charged trivacancy‐type defects VZn+O+Zn as the predominant positron trapping sites within the nanocrystallites. They got converted to neutral divacancies (VZn+O) on doping with manganese (Mn). Further doping resulted in the reduction of the size of the nanocrystallites. At still increased doping concentrations, a new phase ZnMn2O4 was formed. It had a normal spinel structure with positron trapping centers at some of the tetrahedral and octahedral sites. X‐ray diffraction and transmission electron micro‐scopy studies confirmed these findings. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Migration behavior of vacancies in electron irradiated Fe‐Cu alloys
Authors: Cao Xingzhong , Xu Qiu , Sato Koichi , Yoshiie Toshimasa 
Published: October 2009

AbstractThe formation of Cu precipitates in Cu containing steels is one of the key factors leading to embrittlement in reactor pressure vessel steels. Cu precipitates are formed by the migration of vacancies in steels and the behaviour of these vacancies is therefore important. In the present study, vacancies were introduced into Fe‐Cu alloys by electron irradiation with 28 MeV at 100 K. The effects of Cu concentration and tiny Cu precipitates on the migration of vacancies and growth of precipitates in Fe‐Cu alloys were investigated by positron annihilation lifetime measurements. The effect of Cu concentration between Fe‐0.3 mass% Cu to Fe‐0.6 mass% Cu on the migration of vacancies and the formation of Cu precipitates was negligible small. The formation of Cu precipitates was found to decrease the migration temperature of vacancies. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Positron annihilation studies of NiO nanoparticles prepared through two different chemical routes
Authors: Das Soumen , Ghoshal Tandra , Nambissan P. M. G. 
Published: October 2009

AbstractNanocrystalline samples of nickel oxide were synthesized through solvothermal and sol‐gel routes, and the grain sizes were determined through x‐ray diffraction and transmission electron microscopy. Fourier transform infrared, optical absorption and positron annihilation spectroscopy studies were done to characterize them further and study the defects at nanoscale. The onset of quantum confinement effects is indicated by characteristic blue‐shift in optical absorption spectra and widening of the band gap. Positron annihilation parameters changed as a result and the causes are discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vorticity, deformation and divergence signals associated with stratosphere–troposphere exchange
Authors: Jaeger E. B. , Sprenger M. 
Published: October 2009

AbstractThe dynamical tropopause of the extratropics, defined as an isosurface of potential vorticity, acts as a barrier to stratosphere–troposphere exchange (STE). Therefore, any transport across this barrier is necessarily associated with diabatic or frictional processes such as turbulence, radiative forcing or condensational heating. Most of these processes are linked to distinct flow phenomena and hence with distinct signatures of the velocity field. The focus of this study is on the characteristics of the velocity field at the time and location of the tropopause crossing, as given by the flow‐components divergence (DIV), deformation (DEF) and vorticity (VORT). Firstly, the prevalence of distinct signals is shown for three case studies. Then a Lagrangian climatology of STE is used to assess the climatological aspects of this link for the year 1990. Methodologically, the flow‐field components are traced along the STE trajectories, both derived from ERA‐40. Some key results of this study are as follows. (1) DEF, positive values of VORT and negative values of DIV are markedly correlated with stratosphere‐to‐troposphere transport (STT). Therefore, the typical flow field associated with STT is deformative, cyclonic and convergent. (2) For troposphere‐to‐stratosphere transport (TST), the link with the flow‐field components is less pronounced. DEF, VORT and DIV all show small, but distinct local maxima just before the exchange. The flow field during TST is therefore rather divergent and less cyclonic. (3) Sensitivity studies reveal that these findings are robust with respect to temporal and spatial variability. Copyright © 2009 Royal Meteorological Society
A context‐aware handover decision based on user perceived quality of service trigger
Authors: Ghahfarokhi Behrouz Shahgholi , Movahhedinia Naser 
Published: October 2009

AbstractGrowing demands for pervasive and ubiquitous services over wireless mobile networks and evolution of such networks towards heterogeneous solutions have emphasized the necessity of more intelligent handoff decisions. The existing handoff management methods in the literature are mostly using signal strength measurements and other link quality evaluations not addressing the knowledge about context of mobile devices, users and networks. Recently, context‐aware handoff management has been considered as a novel candidate for fourth generation (4G) wireless technology. In this paper, user perceived quality of service has been considered in addition to traditional contexts such as user preferences, application requirements, network parameters and link quality for decision making. User perceived quality (UPQ) has been employed as a trigger source, in addition to link layer triggers which are emerged using media independent handover (MIH) event service. This paper presents a policy based mechanism for handoff decision making where fuzzy petri nets (FPNs) have been utilized as its evaluation algorithm. A case study has been provided by simulations to show the usability and user level satisfaction. Simulation results show superior performance in terms of UPQ, jitter and packet delivery measures. Copyright © 2009 John Wiley & Sons, Ltd.
Efficient ARQ protocols with anti‐jamming coding for cognitive radios
Authors: Yue Guosen , Wang Xiaodong 
Published: October 2009

AbstractWe introduce simple yet efficient automatic retransmission request (ARQ) protocols in conjunction with two types of anti‐jamming coding techniques—rateless coding and piecewise coding—for protecting secondary users' data transmissions in cognitive radio systems. For piecewise coding, we propose to employ systematic codes to facilitate efficient selected retransmissions and design short codes to maximize secondary user throughput. For rateless coding, we consider a protocol that transmits new parity packets during retransmission and show that this scheme is stable if the jamming rate of the system is within a certain range. It is seen that for both anti‐jamming coding schemes, the corresponding simple ARQ protocols provide significant improvement in secondary user throughput. Moreover, the piecewise coding together with its ARQ protocol offers similar or better throughput performance compared with the rateless coding counterpart, without incurring the stability issue. Copyright © 2009 John Wiley & Sons, Ltd.
Unroofing and Curettage for the Treatment of Acute and Chronic Pilonidal Disease
Authors: Kepenekci Ilknur , Demirkan Arda , Celasin Haydar , Gecim Ibrahim Ethem 
Published: October 2009

AbstractBackgroundVarious surgical techniques are available in the management of pilonidal sinus, but controversy concerning the optimal surgical approach persists. The present study analyzes the outcome of unroofing and curettage as the primary intervention for acute and chronic pilonidal disease.MethodsA total of 297 consecutive patients presenting with chronic disease, acute abscess, or recurrent disease were treated with unroofing and curettage. The wound was left open to heal by secondary intention. Hospitalization, time required to resume daily activities and return to work, healing time, and recurrence rates were recorded.ResultsAll patients were discharged within the first 24 h after operation. The median period before returning to work was 3.2 ± 1.2 days, and the mean time for wound healing was 5.4 ± 1.1 weeks. Six patients were readmitted with recurrence of the disease within the first six postoperative months. All recurrences were in patients who did not follow the wound care advice and who did not come to regular weekly appointments. Patients with recurrence underwent repeat surgery by the same technique with good results.ConclusionsUnroofing and curettage for pilonidal sinus disease is an easy and effective technique. The vast majority of the patients, including those with abscess as well as those with chronic disease, will heal with this simple procedure, after which even recurrences can be managed successfully with the same procedure. Relying on these results, we advocate unroofing and curettage as the procedure of choice in the management of pilonidal disease.
“Blitz Surgery”: Redefining Surgical Needs, Training, and Practice in Sub‐Saharan Africa
Authors: Nthumba Peter M. 
Published: October 2009

AbstractBackgroundMost reconstructive surgery in Sub‐Saharan Africa is provided by numerous noncoordinated individuals and organizations, in multiple short trips, or “surgical blitzes.” Because many such groups do not train local surgeons, these communities have become dependent on unsustainable systems. By providing much‐needed care to otherwise neglected areas, the blitzes offer an easy solution to what would otherwise be the source of a significant headache to local governments.MethodsThe collection of data and other material in this highly ambiguous and fluid field is nearly impossible, as scientific papers on the results of poor surgical treatment, especially in the realm of humanitarian medicine, do not exist: The author has had to rely on personal experience and community interaction to reach the views and conclusions articulated in this article.ResultsAlthough not the rule, blitz surgeries have poorer outcomes than in‐hospital procedures, primarily because of inadequate preoperative and postoperative care.ConclusionsAlthough the value of blitz surgery in meeting some of the surgical needs of otherwise neglected communities is undeniable, the author seeks to provoke a sober reexamination of these efforts vis‐à‐vis the long‐term sustainability of such programs, with the objective of harnessing strengths that would see the evolution of a new reconstructive surgical service tailor‐made for Africa—affordable and sustainable yet able to deliver quality surgical care to the remotest villages. Otherwise, these humanitarian efforts’ will continue to be ‘drops in the ocean, meeting the needs of a few in the community but resulting in no long‐term gains.
Facile Fabrication of Ultrafine Hollow Silica and Magnetic Hollow Silica Nanoparticles by a Dual-Templating Approach
Authors: Wu Wei , Xiao Xiangheng , Zhang Shaofeng , Fan Lixia , Peng Tangchao , Ren Feng , Jiang Changzhong 
Published: October 2009

Abstract
The development of synthetic process for hollow silica materials is an issue of considerable topical interest. While a number of chemical routes are available and are extensively used, the diameter of hollow silica often large than 50 nm. Here, we report on a facial route to synthesis ultrafine hollow silica nanoparticles (the diameter of ca. 24 nm) with high surface area by using cetyltrimethylammmonium bromide (CTAB) and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as co-templates and subsequent annealing treatment. When the hollow magnetite nanoparticles were introduced into the reaction, the ultrafine magnetic hollow silica nanoparticles with the diameter of ca. 32 nm were obtained correspondingly. Transmission electron microscopy studies confirm that the nanoparticles are composed of amorphous silica and that the majority of them are hollow.
Size-Controlled Synthesis of Colloidal Gold Nanoparticles at Room Temperature Under the Influence of Glow Discharge
Authors: Liang Xi , Wang Zhou-jun , Liu Chang-jun 
Published: October 2009

Abstract
Highly dispersed colloidal gold (Au) nanoparticles were synthesized at room temperature using glow discharge plasma within only 5 min. The prepared Au colloids were characterized with UV–visible absorption spectra (UV–vis), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) equipped with an energy dispersion X-ray spectrometer (EDX). UV–vis, XPS and EDX results confirmed that Au3+ ions in HAuCl4 solution could be effectively reduced into the metallic state at room temperature with the glow discharge plasma. TEM images showed that Au nanoparticles were highly dispersed. The size of colloidal Au nanoparticles could be easily tuned in the nanometer range by adjusting the initial concentration of HAuCl4 solution. Moreover, the as-synthesized Au colloids (d
av = 3.64 nm) exhibited good catalytic activity for glucose oxidation. The nucleation and growth of colloidal Au particles under the influence of the plasma was closely related with the high-energy electrons generated by glow discharge plasma.
Is it the music? Peer substance use as a mediator of the link between music preferences and adolescent substance use
Authors: Mulder Juul , Ter Bogt Tom F.M. , Raaijmakers Quinten A.W. , Nic Gabhainn Saoirse , Monshouwer Karin , Vollebergh Wilma A.M. 
Published: October 2009

ABSTRACTBoth music preferences and the substance use behavior of peers are important elements in explaining adolescent substance use. The extent to which music preference and peer use overlap in explaining adolescent substance use remains to be determined. A nationally representative sample of 7324 Dutch school‐going adolescents (aged 12–16) provided data on music preferences, substance use behaviors and perceived number of peers using substances. Factor analyses showed that preferences for eight music genres factored into four styles: Pop (chart music, Dutch pop), Adult (classical music, jazz), Urban (rap/hiphop, soul/R&B) and Hard (punk/hardcore, techno/hardhouse); substance use was indicated by smoking, drinking, and cannabis use. Structural equation modeling revealed that the relationship between music preference and substance use was either wholly or partially mediated by perceived peer use. Music can model substance use and fans of different types of music may select friends with use patterns that reinforce their own substance use inclinations.
The role of N‐methyl‐d‐aspartate receptor subunit NR2B in spinal cord in cancer pain
Authors: Gu XiaoPing , Zhang Juan , Ma ZhengLiang , Wang JunHua , Zhou XiaoFang , Jin YanQing , Xia XiaoPing , Gao Qin , Mei FengMei 
Published: October 2009

AbstractCancer pain is one kind of the most common and severe kinds of chronic pain. No breakthrough regarding the mechanisms and therapeutics of cancer pains has yet been achieved. Based on the well established involvement of the NMDA (N‐methyl‐d‐aspartate) receptor containing NR2B in inflammatory pain and neuropathic pain and the effective pain relief obtained with ketamine in cancer patients with intractable pain, we supposed that NR2B in the spinal cord was an important factor for cancer pain. In this study, we investigated the possible role of NR2B in the spinal cord using a murine model of bone cancer pain. C3H/HeJ mice were inoculated into the intramedullary space of the right femur with Osteosarcoma NCTC 2472 cells to induce ongoing bone cancer‐related pain behaviors. At day 14 after operation, the expression of NR2B mRNA and NR2B protein in the spinal cord were higher in tumor‐bearing mice compared to the sham mice. Intrathecal administration of 5 and 10 μg of NR2B subunit‐specific NMDA receptor antagonist ifenprodil attenuated cancer‐evoked spontaneous pain, thermal hyperalgesia and mechanical allodynia. These results suggest that NR2B in the spinal cord may participate in bone cancer pain in mice, and ifenprodil may be a useful alternative or adjunct therapy for bone cancer pain. The findings may lead to novel strategies for the treatment of bone cancer pain.