bluuebunny/crossref_metadata_2025 huggingface dataset:
The 0.3-kb fragment containing the R-U5-5’leader sequence of Friend murine leukemia virus influences the level of protein expression from spliced mRNA
Authors: Choo Yeng Cheng , Seki Yohei , Machinaga Akihito , Ogita Nobuo , Takase-Yoden Sayaka
Published: April 2013

Background

A neuropathogenic variant of Friend murine leukemia virus (Fr-MLV) clone A8 induces spongiform neurodegeneration when infected into neonatal rats. Studies with chimeras constructed from the A8 virus and the non-neuropathogenic Fr-MLV clone 57 identified a 0.3-kb KpnI-AatII fragment containing a R-U5-5’leader sequence as an important determinant for inducing spongiosis, in addition to the env gene of A8 as the primary determinant. This 0.3-kb fragment contains a 17-nucleotide difference between the A8 and 57 sequences. We previously showed that the 0.3-kb fragment influences expression levels of Env protein in both cultured cells and rat brain, but the corresponding molecular mechanisms are not well understood.

Results

Studies with expression vectors constructed from the full-length proviral genome of Fr-MLV that incorporated the luciferase (luc) gene instead of the env gene found that the vector containing the A8-0.3-kb fragment yielded a larger amount of spliced luc-mRNA and showed higher expression of luciferase when compared to the vector containing the 57-0.3-kb fragment. The amount of total transcripts from the vectors, the poly (A) tail length of their mRNAs, and the nuclear-cytoplasm distribution of luc-mRNA in transfected cells were also evaluated. The 0.3-kb fragment did not influence transcription efficiency, mRNA polyadenylation or nuclear export of luc-mRNA. Mutational analyses were carried out to determine the importance of nucleotides that differ between the A8 and 57 sequences within the 0.3-kb fragment. In particular, seven nucleotides upstream of the 5’splice site (5’ss) were found to be important in regulating the level of protein expression from spliced messages. Interestingly, these nucleotides reside within the stem-loop structure that has been speculated to limit the recognition of 5’ss.

Conclusions

The 0.3-kb fragment containing the R-U5-5’leader sequence of Fr-MLV influences the level of protein expression from the spliced-mRNA by regulating the splicing efficiency rather than transcription, nuclear export of spliced-mRNA, or poly (A) addition to mRNA. Seven nucleotides in the 0.3-kb fragment, which reside within the stem-loop structure that has been speculated to limit recognition of the 5’ss, could pinpoint the function of this region.
Eating from the wild: diversity of wild edible plants used by Tibetans in Shangri-la region, Yunnan, China
Authors: Ju Yan , Zhuo Jingxian , Liu Bo , Long Chunlin
Published: April 2013

Background

Locally harvested wild edible plants (WEPs) provide food as well as cash income for indigenous people and are of great importance in ensuring global food security. Some also play a significant role in maintaining the productivity and stability of traditional agro-ecosystems. Shangri-la region of Yunnan Province, SW China, is regarded as a biodiversity hotspot. People living there have accumulated traditional knowledge about plants. However, with economic development, WEPs are threatened and the associated traditional knowledge is in danger of being lost. Therefore, ethnobotanical surveys were conducted throughout this area to investigate and document the wild edible plants traditionally used by local Tibetan people.

Methods

Twenty-nine villages were selected to carry out the field investigations. Information was collected using direct observation, semi-structured interviews, individual discussions, key informant interviews, focus group discussions, questionnaires and participatory rural appraisal (PRA).

Results

Information about 168 wild edible plant species in 116 genera of 62 families was recorded and specimens were collected. Most species were edible greens (80 species) or fruits (78). These WEPs are sources for local people, especially those living in remote rural areas, to obtain mineral elements and vitamins. More than half of the species (70%) have multiple use(s) besides food value. Some are crop wild relatives that could be used for crop improvement. Several also have potential values for further commercial exploitation. However, the utilization of WEPs and related knowledge are eroding rapidly, especially in the areas with convenient transportation and booming tourism.

Conclusion

Wild food plants species are abundant and diverse in Shangri-la region. They provide food and nutrients to local people and could also be a source of cash income. However, both WEPs and their associated indigenous knowledge are facing various threats. Thus, conservation and sustainable utilization of these plants in this area are of the utmost importance. Documentation of these species may provide basic information for conservation, possibly further exploitation, and will preserve local traditional knowledge.
A selective pretreatment method for determination of endogenous active brassinosteroids in plant tissues: double layered solid phase extraction combined with boronate affinity polymer monolith microextraction
Authors: Ding Jun , Mao Li-Jing , Yuan Bi-Feng , Feng Yu-Qi
Published: April 2013

Background

Brassinosteriods (BRs), a group of important phytohormones, have various effects on plant growth and development. However, their physiological functions in plants have not been fully understood to date. Endogenous BRs in plant tissue are extremely low and the elucidation of BRs functions relies on sensitive detection method. Reported methods for the determination of BRs required large amount of plant tissue, tedious pretreatment process, and were lack of selectivity. Therefore, development of a simple and selective method for the sensitive quantification of BRs is highly needed.

Results

We established a pretreatment method of BRs in plant tissues by employing double layered solid phase extraction (DL/SPE) combined with boronate affinity polymer monolith microextraction (BA/PMME). After the initial depigmentation with DL/SPE cartridge, BA/PMME was employed to selectively extract BRs from sample matrix. Uniquely, most sample matrix was successfully removed by BA monolith purification. Using this method, BRs was determined by liquid chromatography-mass spectrometry (LC-MS). Endogenous active BRs could be detected in only 1 g fresh weigh (FW) leaves or 0.5 g FW flower tissues.

Conclusion

A DL/SPE-BA/PMME pretreatment method for the determination of endogenous brassinosteroids in plant tissues was developed and validated. The proposed method was sensitive and selective. Besides, it may be further developed for the determination of other BRs including their precursors and conjugates.
Long term study on the effect of mollusciciding with niclosamide in streamhabitats on the transmission of schistosomiasis mansoni after community-basedchemotherapy in Makueni District, Kenya
Authors: Kariuki Henry C , Madsen Henry , Ouma John H , Butterworth Anthony E , Dunne David W , Booth Mark , Kimani Gachuhi , Mwatha Joseph K , Muchiri Eric , Vennervald Birgitte J
Published: April 2013

Background

Schistosoma mansoni infection is a persistent public health problemin many Kenyan communities. Although praziquantel is available, re-infectionafter chemotherapy treatment is inevitable, especially among children.Chemotherapy followed by intermittent mollusciciding of habitats ofBiomphalaria pfeifferi, the intermediate host snail, may havelonger term benefits, especially if timed to coincide with naturalfluctuations in snail populations.

Methods

In this cohort study, the Kambu River (Intervention area) was molluscicidedintermittently for 4 years, after mass chemotherapy with praziquantelin the adjacent community of Darajani in January 1997. The nearby ThangeRiver was selected as a control (Non-intervention area), and its adjacentcommunity of Ulilinzi was treated with praziquantel in December 1996. Snailnumbers were recorded monthly at 9–10 sites along each river, whilerainfall data were collected monthly, and annual parasitological surveyswere undertaken in each village. The mollusciciding protocol was adapted tolocal conditions, and simplified to improve prospects for widespreadapplication.

Results

After the initial reduction in prevalence attributable to chemotherapy, therewas a gradual increase in the prevalence and intensity of infection in thenon-intervention area, and significantly lower levels of re-infectionamongst inhabitants of the intervention area. Incidence ratio between areasadjusted for age and gender at the first follow-up survey, 5 weeksafter treatment in the non-intervention area and 4 months aftertreatment in the intervention area was not significant (few people turnedpositive), while during the following 4 annual surveys these ratios were0.58 (0.39-0.85), 0.33 (0.18-0.60), 0.14 (0.09-0.21) and 0.45 (0.26-0.75),respectively. Snail numbers were consistently low in the intervention areaas a result of the mollusciciding. Following termination of themollusciciding at the end of 2000, snail populations and infections insnails increased again in the intervention area.

Conclusion

The results of this study demonstrate that in the Kenyan setting acombination of chemotherapy followed by intermittent mollusciciding can havelonger term benefits than chemotherapy alone.
Clinical significance and gene expression study of human hepatic stellate cells in HBV related-hepatocellular carcinoma
Authors: Liao Rui , Wu Han , Yi Yong , Wang Jia-Xing , Cai Xiao-Yan , He Hong-Wei , Cheng Yun-Feng , Zhou Jian , Fan Jia , Sun Jian , Qiu Shuang-Jian
Published: April 2013

Background

Peritumoral activated hepatic stellate cells (HSCs) are versatile myofibroblast-like cells closely related with hepatocellular carcinoma (HCC) progression. So far, comprehensive comparison of gene expression of human HSCs during hepatocarcinogenesis is scanty. Therefore, we identified the phenotypic and genomic characteristics of peritumoral HSCs to explore the valuable information on the prognosis and therapeutic targets of HBV related HCC.

Methods

A tissue microarray containing 224 HBV related HCC patients was used to evaluate the expression of phenotype markers of HSCs including α-SMA, glial fibrillary acidic protein (GFAP), desmin, vinculin and vimentin. HSCs and cancer associated myofibroblasts (CAMFs) were isolated from normal, peritumoral human livers and cancer tissues, respectively. Flow cytometry and gene microarray analysis were performed to evaluate the phenotypic changes and gene expression in HCC, respectively.

Results

Peritumoral α-SMA positive HSCs showed the prognostic value in time to recurrence (TTR) and overall survival (OS) of HCC patients, especially in early recurrence and AFP-normal HCC patients. Expression of GFAP positive HSCs cell lines LX-2 was significantly decreased after stimulation with tumor conditioned medium. Compared with quiescent HSCs, peritumoral HSCs and intratumoral CAMFs expressed considerable up- and down-regulated genes associated with biological process, cellular component, molecular function and signaling pathways involved in fibrogenesis, inflammation and progress of cancer.

Conclusions

Peritumoral activated HSCs displayed prognostic value in HBV related-HCC, and their genomic characteristics could present rational biomarkers for HCC risk and promising therapeutic targets.
Developmental potential of human oocytes matured in vitro followed by vitrification and activation
Authors: Imesch Patrick , Scheiner David , Xie Min , Fink Daniel , Macas Erwin , Dubey Raghvendra , Imthurn Bruno
Published: April 2013

Background

Oocyte in vitro maturation (IVM) and cryopreservation at the time of routine ovarian tissue freezing may be offered to cancer patients as an additional option for fertility preservation. This study aimed to investigate the developmental capacity of oocytes isolated from unstimulated ovaries.

Methods

Immature oocytes (n = 63) from seven consenting premenopausal patients were analysed. Oocytes were collected during routine laparoscopic examination with biopsy of an ovary (cystic adnexal mass, n = 3; cervical adenocarcinoma, n = 2) or oophorectomy (sex reassignment surgery, n = 2) without previous stimulation of the ovaries. The stage of the patient’s menstrual cycle was not considered. Oocytes in all visible antral follicles were aspirated from ovaries, cultured in IVM medium and vitrified at the MII stage before being kept in liquid nitrogen for at least one month. After warming, oocytes were subjected to parthenogenetic activation by chemical stimulus. Their further development was recorded at intervals of 24 hours for up to 6 days of culture.

Results

61.9% of oocytes matured in vitro within 48 hours. The survival rate after vitrification and warming was 61.5%. A total of 75% of surviving oocytes were able to respond to artificial activation, 44.4% of the parthenotes developed to early embryonic stage. However, only 1 in 18 (5.6%) of the resulting embryos reached blastocyst stage.

Conclusions

Oocytes matured in vitro from unstimulated ovaries seem to have limited developmental potential after cryopreservation and artificial activation. Although the outcome of IVM for non-stimulated oocytes is poor, it is currently the only chance besides cryopreservation of ovarian tissue for women for whom ovarian stimulation is not possible due to life circumstances. Based on our preliminary results, we suggest that the use of cryopreserved ovaries for fertility preservation in women with cancer warrants further investigation.
Did the 2007 welfare reforms for low income parents in Australia increase welfare exits?
Authors: Fok Yin King , McVicar Duncan
Published: April 2013

This paper examines the impacts of recent Australian welfare to work reforms for low-income parents of school-aged children who had been in receipt of Parenting Payment – the main welfare payment for this group – for at least one year. Specifically, the reforms introduced a requirement to engage in at least 15 hours of work-related activity per week from the youngest child’s seventh birthday. As was the case for similar reforms introduced by US states in the 1990s, these reforms had large, statistically significant and positive impacts on the hazard rates for exiting the welfare payment. Two thirds of these exits were exits from welfare altogether and one third were exits to other welfare payments.

JEL

I38, J22
Wind tunnel testing and numerical simulation on aerodynamic performance of a three-bladed Savonius wind turbine
Authors: Morshed Khandakar Niaz , Rahman Mosfequr , Molina Gustavo , Ahmed Mahbub
Published: April 2013

The purpose of this research work is to investigate experimentally and computationally the feasibility of improving the performance of the vertical-axis Savonius wind turbine. The authors first performed a series of wind tunnel investigations on semi-cylindrical three-bladed Savonius rotor scale models with different overlap ratios and without overlap. These experiments were conducted in front of a low-speed subsonic wind tunnel at different Reynolds numbers. Pressures around the concave and convex surfaces of each blade, as well as the static torque for the rotor models, were measured. Using these experimental data, the authors calculated aerodynamic characteristics such as drag coefficients, static torque coefficients, and power coefficients. The authors then performed computational fluid dynamics (CFD) simulations using the commercial CFD software FLUENT and GAMBIT to analyze the static rotor aerodynamics of those models. The experimental and computational results were then compared for verification. Three different models with different overlap ratios were designed and fabricated for the current study to find the effect of overlap ratios. The results from the experimental part of the research show a significant effect of overlap ratio and Reynolds number on the improvement of aerodynamic performance of the Savonius wind turbine. At higher Reynolds number, the turbine model without overlap ratio gives better aerodynamic coefficients, and at lower Reynolds number, the model with moderate overlap ratio gives better results.
Neuroprotective effects of D-Ala2GIP on Alzheimer's disease biomarkers in an APP/PS1 mouse model
Authors: Faivre Emilie , Hölscher Christian
Published: April 2013

Introduction

Type 2 diabetes mellitus has been identified as a risk factor for Alzheimer's disease (AD). An impairment of insulin signaling as well as a desensitization of its receptor has been found in AD brains. Glucose-dependent insulinotropic polypeptide (GIP) normalises insulin signaling by facilitating insulin release. GIP directly modulates neurotransmitter release, LTP formation, and protects synapses from the detrimental effects of beta-amyloid fragments on LTP formation, and cell proliferation of progenitor cells in the dentate gyrus. Here we investigate the potential therapeutic property of the new long lasting incretin hormone analogue D-Ala2GIP on key symptoms found in a mouse model of Alzheimer' disease (APPswe/PS1detaE9).

Methods

D-Ala2GIP was injected for 21 days at 25 nmol/kg ip once daily in APP/PS1 male mice and wild type (WT) littermates aged 6 or 12 months of age. Amyloid plaque load, inflammation biomarkers, synaptic plasticity in the brain (LTP), and memory were measured.

Results

D-Ala2GIP improved memory in WT mice and rescued the cognitive decline of 12 months old APP/PS1 mice in two different memory tasks. Furthermore, deterioration of synaptic function in the dentate gyrus and cortex was prevented in 12 months old APP/PS1 mice. D-Ala2GIP facilitated synaptic plasticity in APP/PS1 and WT mice and reduced the number of amyloid plaques in the cortex of D-Ala2GIP injected APP/PS1 mice. The inflammatory response in microglia was also reduced.

Conclusion

The results demonstrate that D-Ala2GIP has neuroprotective properties on key hallmarks found in AD. This finding shows that novel GIP analogues have the potential as a novel therapeutic for AD.
Analysis and design of RNA sequencing experiments for identifying RNA editing and other single-nucleotide variants
Authors: Lee Jae-Hyung , Ang Jason K. , Xiao Xinshu
Published: April 2013

RNA-sequencing (RNA-Seq) technologies hold enormous promise for novel discoveries in genomics and transcriptomics. In the past year, a surge of reports has analyzed RNA-Seq data to gain a global view of the RNA editome. Opposing results have been presented, giving rise to extensive debate surrounding one of the first such studies in which a daunting list of all 12 types of RNA–DNA differences (RDDs) were identified. Although a consensus is forming that some of the initial “paradigm-shifting” results of this study may be questionable, recent reports on this topic differed in terms of the number and relative abundance of each type of RDD. Many outstanding issues exist, most importantly, the choice of bioinformatic approaches. Here we discuss the critical data analysis and experimental design issues of such studies to enable improved systematic investigation of the largely unexplored frontier of single-nucleotide variants in RNA.
BOLOGNA ARRANGEMENTS AND INTELLECTUAL MIGRATION: MAIN OBJECTIVES, DIRECTIONS OF REALIZATION, TRENDS, PROBLEMS, PROSPECTS
Authors: Куценко  , Kutsenko Viktoriya
Published: April 2013

Preconditions of development of Bologna arrangements on creation of uniform educational space, their main objectives and realization directions are briefl y stated in this article. The main attention is paid to the analysis of impact mechanisms on mobility increasing of students and teachers of higher educational institutions as important element of all-European educational space formation.The special place is allocated for defi nition of Russia’s role in the global market of educational services, for identifi cation of the most signifi cant problems of Russian education which reduce its competitiveness in the international market, and for development of scientifi c and practical recommendations on optimization of intellectual migration regulation system in the Russian Federation.
COMPETITIVENESS OF RUSSIAN HIGHER EDUCATION INSTITUTIONS’ GRADUATES IN PERSONNEL MANAGEMENT SPECIALTY ON THE LABOR MARKE
Authors: Дмитриева  , Dmitriyeva Yuliya
Published: April 2013

One of debatable problems − competitiveness of higher education institutions’ graduates is considered in this article. It is rather new problem has appeared at penetration of market relations into higher school life. However the idea of what is the basis for competitiveness of higher education institutions’ graduates still remains superficial and often unilateral. Offered article will help to understand what the competitiveness consists of and how it is estimated, what is the real level of competitiveness that have personnel management specialty graduates and what reserves of its increasing exist.
ANNIVERSARY OF PERSONNEL MANAGEMENT CHAIR OF NORTHWEST INSTITUTE OF MANAGEMENT — RUSSIAN ACADEMY OF NATIONAL ECONOMY AND PUBLIC ADMINISTRATION UNDER THE PRESIDENT OF THE RUSSIAN FEDERATION
Authors: Голянич  , Golyanich Valeriy
Published: April 2013

History of creation and formation of Personnel Management Chair of Northwest Institute of Management — Russian Academy of National Economy and Public Administration under the President of the Russian Federation, main areas of Chair’s activity are considered in this article.
REVIEWS
Authors: Weiner Nathaniel
Published: April 2013

SOMEDAY ALL THE ADULTS WILL DIE! PUNK GRAPHICS 1971–1984, CURATED BY JOHAN KUGELBERG AND JOHN SAVAGE Hayward Gallery Project Space, Southbank Centre, London, 14 September–4 November 2012

PUNK: AN AESTHETIC, JOHAN KUGELBERG AND JOHN SAVAGE (EDS), ESSAYS BY WILLIAM GIBSONW,
LINDER STERLING AND GEE VAUCHER (2012) New York: Rizzoli, 352 pp., ISBN 9780847836628, h/bk, £35.00
Fast, cheap and out of control: The graphic symbol in hardcore punk
Authors: Larsen Al
Published: April 2013

Extremely simple graphic symbols were central to the visual culture of the first wave of American hardcore punk. Simple enough to be easily drawn by hand, their accessibility was important to the lived experience of hardcore values of participation and collectivity and contributed to
the spread of the subculture outside of commercial channels in the early 1980s. While early British punk had provided models for the critical appropriation of graphic symbols of power, the use of symbols in hardcore was played out between conflicting approaches - the negation and critique
of symbols of power as modelled by UK collective Crass and the invention of original, enigmatic branding marks as modelled by the US punk band Germs.
Influence of Test Machine Control Method on Apparent Performance of ASTM C1550 Fiber Reinforced Concrete Panels
Authors: Bernard E. S.
Published: April 2013

The ASTM C1550 round panel test is used to assess the post-crack performance of fiber reinforced concrete (FRC) and fiber reinforced shotcrete (FRS) and has become firmly established as the most repeatable means of post-crack performance assessment available for these materials. When the test method was first published, two methods of test machine control were permitted: displacement control, in which the displacement of the loading actuator is used as the control parameter in the test, and strain control, in which the central deflection of the specimen is used as the controlling parameter. Both these methods of control, however, require expensive testing machines, with the result that some operators have used cheaper open-loop machines to test ASTM C1550 round panels. Doubts have arisen among specifiers of FRC and FRS in tunneling and mining projects as to whether specimens tested using open-loop machines result in the same apparent performance as would be expected using displacement- or strain-controlled testing machines. This investigation has established that under certain circumstances, an open-loop testing machine can produce results for ASTM C1550 panels that are similar to results obtained using a strain- or displacement-controlled testing machine. It was also found that the measurement of specimen deflection on the underside of the panel is problematic at large deformations and can lead to substantial variations in apparent performance.
Crystal structure of bis(acetonitrile-κN)-tetrakis-μ-(p-nitrobenzoato- κ2O:O')copper(II) – (Cu–Cu), Cu2(p-NO2C6H4COO)4(CH3CN)2, C16H11CuN3O8
Authors: Song Shu-Tao , Cui Jun-Yan , Li Zhen , Nie Feng-Mei
Published: April 2013

C16H11CuN3O8, tetragonal, I41/a (no. 88), a = 17.1139(2) Å, c = 25.5803(5) Å, V = 7492.1 Å3, Z = 16, Rgt(F) = 0.0409, wRref(F2) = 0.1261, T = 296 K.
The Impact of Biomaterials Research on Tissue Engineering
Authors: Vacanti Charles A.
Published: April 2013

The three most important components of tissue engineering are biomaterials, cellular biology, and vascular supply. Biomaterials are needed to control the delivery of new cells into the body. In the absence of biomaterials, cells that are injected into a vein, a cavity, or tissue tend to disperse, so a sufficiently high density of cells to perform the intended function—replacement or repair of a damaged structure—is never achieved.1 A porous delivery system is needed that confines the cells to the desired location and promotes their nourishment until blood vessels grow in and new tissue is formed. Biomaterials such as plastics can provide such a porous delivery system.
Polyaniline–Si Nanoparticle Nanocapsules as a Dual Photovoltaic Sensitizer
Authors: Maximenko Yulia , Elhalawany Noha , Mantey Kevin , Yamani Zain , Yau Siu-Tung , Nayfeh Munir H.
Published: April 2013

We examine the optical and structural properties of polyaniline–silicon nanoparticle capsules — a novel organic/inorganic material. The Si particles absorb UV/blue efficiently and green moderately, while polyaniline (PANI) in its green emeraldine state absorbs UV and red/IR efficiently, effectively providing absorption over a wide range of the solar spectrum. The capsules are produced by miniemulsion of aniline monomers in the presence of Si nanoparticles. Thin films of the capsules were formed on a variety of substrates. We use high resolution transmission electron microscopy (HTEM) and scanning electron microscopy (SEM) to record the structural properties. We also monitor the optical properties of the Si core and the PANI shell using fluorescence microscopy under UV and visible irradiation. Upon on-off cycles of UV irradiation and visible light, the red core switches reversibly between bright and dark states while PANI switches reversibly between emeraldine green and pernigraniline violet states. The results are analyzed in terms of excitonic excitation, charge separation, and transport between the core and the shell, which is useful for photovoltaic applications.
Heavy-to-light hole intersubband absorption in the valence band of GaAs/AlAs heterostructures
Authors: Hossain M. I. , Ikonic Z. , Watson J. , Shao J. , Harrison P. , Manfra M. J. , Malis O.
Published: April 2013

We performed a thorough investigation of mid-infrared heavy-to-light hole intersubband absorption in the valence band of p-doped GaAs quantum wells with AlAs barriers. For the p-type doping a high-purity solid carbon source was used. The experimental results are compared with theoretical simulations. The inclusion of layer inter-diffusion well reproduces the transition energies. We estimate a 6-10 Å inter-diffusion length that is consistent with electron microscopy measurements. A careful analysis of our results provides valuable information for further design of emitters and detectors based on hole intersubband transitions in the valence band.
Engineering the morphology and optical properties of InP-based InAsSb/InGaAs nanostructures via Sb exposure and graded growth techniques
Authors: Lei W. , Tan H.H. , Jagadish C.
Published: April 2013

Two growth techniques - antimony exposure and graded growth, were proposed to achieve the control over the morphology and optical properties of self-assembled InAsSb/InGaAs/InP nanostructures. By exposing the surface of InGaAs buffer layer to trimethylantimony precursor before the growth of InAsSb nanostructures, the surface/interface energy in the system is reduced, while the strain energy in the system is enhanced. This leads to a change of island shape from dot structure to wire structure. By using a higher initial mole fraction of trimethylantimony precursor during the graded growth of InAsSb, more Sb can be incorporated into the InAsSb islands despite the same Sb mole fraction averaged over the graded growth. This also results in a shape change from dot to wire structure. As a result of their shape change, photoluminescence from the InAsSb nanostructures shows different polarization characteristics.
SANS/WANS Time-resolving Neutron Scattering Studiesof Polymer Phase Transitions Using NIMROD
Authors: Mitchell Geoffrey Robert , Bowron Daniel , Mateus Artur , Bartolo Paulo , Gkourmpis Thomas , Phomphrai Khamphee , Lopez Daniel , Davis Fred
Published: April 2013

We use new neutron scattering instrumentation to follow in a single quantitative time-resolving experiment, the three key scales of structural development which accompany the crystallisation of synthetic polymers. These length scales span 3 orders of magnitude of the scattering vector. The study of polymer crystallisation dates back to the pioneering experiments of Keller and others who discovered the chain-folded nature of the thin lamellae crystals which are normally found in synthetic polymers. The inherent connectivity of polymers makes their crystallisation a multiscale transformation. Much understanding has developed over the intervening fifty years but the process has remained something of a mystery. There are three key length scales. The chain folded lamellar thickness is ∼ 10nm, the crystal unit cell is ∼ 1nm and the detail of the chain conformation is ∼ 0.1nm. In previous work these length scales have been addressed using different instrumention or were coupled using compromised geometries. More recently researchers have attempted to exploit coupled time-resolved small-angle and wide-angle x-ray experiments. These turned out to be challenging experiments much related to the challenge of placing the scattering intensity on an absolute scale. However, they did stimulate the possibility of new phenomena in the very early stages of crystallisation. Although there is now considerable doubt on such experiments, they drew attention to the basic question as to the process of crystallisation in long chain molecules. We have used NIMROD on the second target station at ISIS to follow all three length scales in a time-resolving manner for poly(e-caprolactone). The technique can provide a single set of data from 0.01 to 100Å-1 on the same vertical scale. We present the results using a multiple scale model of the crystallisation process in polymers to analyse the results.
Radiation damages on mesoporous silica thin films and bulk materials
Authors: Deschanels X. , Dourdain S. , Rey C. , Toquer G. , Grandjean A. , Pellet-Rostaing S. , Dugne O. , Grygiel C. , Duval F. , Serruys Y.
Published: April 2013

Mesoporous silicas are highly potential materials for applications in the nuclear field like separation, recycling or nuclear wastes confinement. In this work, the effects of the radiation damage on the mesoporous network were investigated by XRR (X-Rays Reflectivity) and nitrogen adsorption isotherm on respectively mesoporous organized thin films (SBA) and disordered bulk mesoporous materials (Vycor glass). The article attempts to answer the question of the existence of a relationship between the rigidity of the mesoporous silica network, and the behavior of silica materials under irradiation.
Effect of high temperature heat treatment on the microstructure and mechanical properties of third generation SiC fibers
Authors: Gosset Dominique , Jankowiak Aurélien , Vandenberghe Thierry , Maxel Maud , Colin Christian , Lochet Nicolas , Luneville Laurence
Published: April 2013

SiC fibers (High Nicalon S -HNS and Tyranno SA3 -Ty-SA3) submitted to heat treatments in neutral atmosphere up to 1900°C were studied by X-ray diffraction (XRD) and TEM observations then submitted to tensile tests up to 1800°C. The microstructural changes in both materials were determined by XRD using a modified Hall-Williamson method introducing an anisotropy parameter taking into account the high density of planar defects of the SiC-3C structure. HNS fibers exhibit significant modifications in the CDD size which drastically increases from 24 nm to 70 nm in the range 1600°C to 1800°C and in the microstrains which decrease from 0.0015 to 0.0005 between 1750°C to 1850°C. Concerning the Ty-SA3 fibers, no evolution of CDD size and microstrains has been observed. The mechanical properties of single fibers were investigated after the heat treatments showing decreases in the tensile strength reaching up to 20% for Tyranno SA3 and 50% for High Nicalon S. The Weibull moduli were also significantly affected. These results are correlated to the fiber structural and microstructural evolutions.
Insertion effect of the 3-nm-thick Co(Pt) layer on AlN preferred orientation and residual stress in the c-axis textured AlN film
Authors: Harumoto Takashi , Muraishi Shinji , Shi Ji , Nakamura Yoshio , Ishiguro Takashi
Published: April 2013

The effect of the continuously inserted 3-nm-thick Co(Pt) layer on the preferred orientation of AlN film is investigated, and highly c-axis textured AlN film has been obtained. According to high resolution transmission electron microscope observations, the preferred orientation of sputter-deposited AlN film is improved from polycrystalline to (001) texture at the interface between AlN and Co(Pt)(111). The texture of AlN films are also examined using an x-ray diffractometer equipped with a two dimensional positive sensitive detector. The x-ray rocking curve full width at half maximum of 002AlN of (001) textured AlN with the Co(Pt) layer is 2.7°, and the residual stress of such specimen is 1.6 GPa in tensile stress.
STM Study of Self-assembly of Quantum Dot Formed by Selective Laser Heating
Authors: Yang Haeyeon , Clegg Casey M.
Published: April 2013

Scanning Tunneling Microscope (STM) was used to examine the morphologies of selfassembled InGaAs quantum dots (QDs). In order to induce the self-assembly, unlike the conventional Stranski-Krastanov (S-K) growth method, spatial thermal modulations in nanoscale were created in-situ on strained-but-flat InGaAs surfaces in a Molecular Beam Epitaxy (MBE) growth reactor by applying interferential irradiations of laser pulses (IILP). As-irradiated surfaces were examined using an attached ultra-high vacuum (UHV) STM. STM images indicate that the irradiation of 7 nano second laser pulse induces self-assembly of QDs. The average size of laser-induced QDs is smaller while their density is larger than that of QDs formed by annealing strained but flat epilayers conventionally. Furthermore, the dot density is modulated sinusoidally with a periodicity commensurate with that of the interference, which suggests that the placement of QDs can be controlled on the scale of the optical wavelength used. QD volume analysis suggests that dots grow faster laterally than vertically so that dots become flattened as they get larger.
Fabrication of Nanostructures of Low-Resistivity Silicon Wafer with High-Aspect-Ratio Using Carbon Nanotube Probe of Scanning Tunneling Microscope
Authors: Matsumuro Akihito , Takagi Makoto
Published: April 2013

Various nanostructures with high-aspect-ratio formed in a low-resistivity silicon wafer by the nano-processing using a carbon nanotube (CNT) probe of a scanning tunneling microscope (STM) have been investigated. The multi-wall CNT probes were obtained with our original pulling-method from CNT dispersion liquid. Nanostructures of point configurations (pit and mound) and line configurations were obtained at the constant tunneling current of 0.1 nA by controlling the bias voltages up to 10 V, processing times up to 300 s and scanning speeds of probe up to 480 nm/s for a line configuration. The aspect-ratio of the pit configuration fabricated at the bias voltage of 3 V increased about 6 times in proportion to the increase in processing time. Remarkable influence of the bias voltage on the configurations indicated that there exists a threshold bias voltage for the transition from the pit configuration to the mound one between 3 V and 5 V, and the aspect ratio of all nanostructures fabricated by the CNT probe were larger than those by a conventional tungsten probe. Finally, cross-sectional TEM observations were also applied to clarify the difference in the formation mechanisms between the pit configuration and the mound configuration. The TEM image of the pit configuration showed neither dislocations nor remarkable strains existed, but in the case of the mound shape TEM analysis indicated the existence of single crystalline silicon region solidified with atomic defects under the mound configuration. Therefore the drastic change of the configurations was attributed to the changes of the atomic-scale microstructures by applying the bias voltages.
Atomic Force Microscopy Investigation of Protein Adsorption on Hydrogenated Amorphous Carbon
Authors: Mughal Muhammad Zeeshan , Lemoine Patrick , Lubarsky Gennady
Published: April 2013

Protein adsorption is the first phenomenon which occurs at nanoscale level when a given surface came into contact with a living fluid cell such as blood. Investigation of this adsorption at nanoscale provides useful information about kinetics and mechanism of conformation of proteins on a given surface. The present study investigates the adsorption of proteins using tapping/intermittent mode atomic force microscopy (T-AFM). The approach taken here is that hydrogenated amorphous carbon coating (a-C:H) is used as a model surface because it is amorphous, smooth, inert and hydrophobic. Two proteins namely albumin and fibrinogen in phosphate buffer (PBS) and de-ionized water are drop casted to study the adsorption kinetics. First and second resonance AFM data was used to investigate the adsorbed layer of proteins. AFM force curve and scratch experiment were used to verify the adhesion and thickness of the adsorbed layer. Combination of height, phase images along with the AFM force curve and scratch experiment shows inhomogeneous distribution of albumin protein in phosphate buffer compared to other protein solutions.
Nanopatterning and plasmonic properties of plasma sputtered gold on diatom frustules
Authors: Romann Julien , Einarsrud Mari-Ann
Published: April 2013

Bio-silica nanostructures from diatoms (called frustules) featuring plasmonic gold nanoparticles (NPs) are elaborated using two methods based on plasma sputtering of gold. The first investigated method uses a thermal treatment to induce the thermal dewetting of a plasma sputtered gold layer on the diatom frustules. The second method first consists of coating the frustules with polyethylene glycol before sputtering gold on these frustules. For both methods, the amount of gold appears to be a key parameter regarding the final obtained layer, which can either be nanostructured by cavities or consist in individual gold NPs. For an amount of sputtered gold equivalent to form a 5 nm thick layer, both methods allow obtaining diatom frustules covered by gold NPs with a size around 20 nm and a narrow size distribution. The UV-visible characterization of the diatom frustules featuring gold NPs highlights a plasmon extinction band in agreement with individual gold NPs with a size below 25 nm.
Theoretical Evaluation of Oxidation Rate of Zr
Authors: Yamamoto Yasunori , Morishita Kazunori , Iwakiri Hirotomo , Kaneta Yasunori
Published: April 2013

First principle calculations were performed to evaluate stress effect on the diffusion process of oxygen vacancy in ZrO2 film, and oxidation rate of Zr was evaluated by solving simple diffusion equations. Our calculation results have indicated that both the vacancy formation and migration energies of ZrO2 increase with increasing compressive applied stress. The energy increase causes a decrease in the diffusion coefficient of oxygen vacancy in ZrO2, leading to a decrease in oxidation rate of Zr. The stress effect on diffusion process may explain the experimental fact that Zr is oxidized in proportion to the cubic root of time.
Efficient Solution Techniques for Multiscale Structural Optimization in Materials Science
Authors: Petrova Svetozara I.
Published: April 2013

We consider the modeling and simulation of multiscale phenomena which arise in finding the optimal shape design of microcellular composite materials with heterogeneous microstructures. The paper focuses on the solution of the resulting partial differential equation (PDE) constrained structural optimization problem and development of efficient multiscale numerical algorithms which are challenging tools in reducing the computational complexity. The modeling strategy is applied in materials science for microstructural ceramic materials of multiple constituents. Our multiscale method is based on the efficient combination of both macroscopic and microscopic models. The homogenization technique based on the concept of strong separation of scales and the asymptotic expansion of the unknown displacements is applied to extract the macroscopic information from the microscale model.

In the framework of all-at-once approach we find a proper combination of the iterative procedure for the nonlinear problem arising from the first order necessary optimality conditions, also known as Karush-Kuhn-Tucker (KKT) conditions, and efficient large-scale solvers for the stress-strain constitutive equation. We use the path-following predictor-corrector schemes by means of Newton's method and fast multigrid (MG) solution techniques. The performance of two preconditioners, incomplete Cholesky (IC) and algebraic multigrid (AMG), for the resulting homogenized state equation is studied. The comparative analysis for both preconditioners in terms of number of iterations and computing times is presented and discussed. Our interests focus on the parallel implementation of the preconditioning techniques and the use of BoomerAMG as a part of the free software library Hypre developed at the Center for Applied Scientific Computing (CASC), Lawrence Livermore National Laboratory (LLNL).
Graphene-like nanostructures obtained from Biomass
Authors: Barin Gabriela Borin , Santos Yane Honorato , Rocha Jennyfer Alves , Pereira da Costa Luiz , Souza Filho Antônio Gomes , de Fátima Gimenez Iara , Barreto Ledjane Silva
Published: April 2013

Two dimensional (2D) carbon nanomaterials such as few graphite layers or graphene are extensively studied due to their unique properties suitable to be exploiting in a wide range of technological applications. Recently, the growth of high quality graphene monolayers using insects and waste as carbon precursors was reported in the literature. This methodology opened a new way to convert the waste carbon into a high-value-added product. In the present work coconut coir dust, an agroindustrial biomass, was used as biotemplate for preparing carbonaceous materials. Carbon structures were synthesized through pyrolysis under nitrogen atmosphere (100mL/min) at 500, 1000, and 1500°C during 2 hours. Starting materials were coconut coir dust in natura and coconut coir dust hydrothermally treated. The samples were characterized by X-ray diffraction, Raman Spectroscopy, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Raman spectra showed the D band for all samples, related to the presence of defects in sp2 carbon structure and G band, indicative of graphite crystallites. It was also observed that the sample carbonized at 1500°C from coconut coir dust treated by hydrothermal method showed G’ band at 2685cm-1 associated with the stacking order along the c-axis. X-ray diffraction analysis showed a broad peak around 2θ= 22° related to the presence of amorphous carbon. By increasing the pyrolysis temperature changes in XRD diffractograms were observed and the sample which was pyrolysed at 1500°C from coconut coir dust hydrothermally treated showed peaks at 2θ= 26.5°, 43° e 45° assigned to (002), (100) (101) graphite plans, respectively. Scanning electron microscopy images showed the presence of overlapping sheets and plates. Transmission Electron Microscopy (TEM) images of coconut coir dust in natura unveiled the formation of amorphous sheet. Coconut coir dust in natura and treated by the hydrothermal method pyrolysed at 1500°C, lead to the formation of some graphitic domains and few graphene layers.
Tratamento cirúrgico da siringomielia pela Técnica de Gardner
Authors: Almeida Gilberto M. , Bianco Eduardo , Shibata Milton K. , Manreza Luiz Alcides , Marchese Antonio J. Tedesco
Published: April 2013

O tratamento cirúrgico da siringomielia é, em geral, considerado decepcionante. Vários tipos de drenagem da cavidade siringomiélica não têm fornecido resultados satisfatórios. Gardner, em magnífica série de trabalhos, mostrou que a siringomielia e as várias malformações associadas à hidrocefalia têm fisiopatogenia única. Baseado em sua teoria, Gardner propôs, em 1958, o bloqueio da comunicação entre o IV ventrículo e o canal central da medula, para o tratamento da siringomielia. Esta técnica não tem sido realizada com muita freqüência. Empregamos o método proposto por Gardner em 4 pacientes, os quais melhoraram após a intervenção cirúrgica.
Delimitação dos núcleos talâmicos pela eletrofisiologia estereotáxica
Authors: Latuf Nilton Luís , Colbachini Marcus J. , Galvão José A. Braz
Published: April 2013

Os limites da área destruída durante a cirurgia estereotáxica são descritos levando em consideração as complicações decorrentes de lesões determinadas erroneamente. São comentados os métodos empregados com a finalidade de controlar a delimitação do alvo, sendo descrita a técnica usada em 23 talamotomias com derivação da atividade elétrica celular dos núcleos talâmicos atravessados e a pesquisa de potenciais evocados, graças à somatotopia da representação táctil no núcleo ventral posterior. Com este método reduz-se de mais ou menos 1 mm o erro radiológico, prescisando-se o alvo terapêutico talâmico nos três planos de espaço.
Fistula liquórica nasal espontânea, sela vazia e restos de adenoma hipofisário
Authors: Cademartori Mario S.
Published: April 2013

É relatado o caso de uma paciente que, aos 20 anos de idade, após episódio de cefaléia fronto-occipital, entrou em amenorréia e, aos 39 anos, apresentou liquorréia nasal com um ano de duração. O estudo radiológico do crânio mostrou aumento das dimensões da sela turcica. O pneumencefalograma mostrou aeração irregular da mesma. Durante a intervenção cirúrgica para correção da fístula, foram encontrados restos de tumor hipofisário sobre o nervo óptico direito; não existia diafragma selar, estando a cavidade selar preenchida por leptomeninge, líquido cefalorraqueano e pequena quantidade de tecido hipofisário no assoalho. O caso fornece razoáveis elementos que comprovam a hipótese de que a atrofia espontânea de tumor hipofisário possa ser considerada como uma das causas que explicam o fato da sela túrcica carecer de conteúdo normal.