Electrical, luminescent, and deep trap properties of Si doped n-GaN grown by pendeo epitaxy

Energy Technology Data Exchange (ETDEWEB)

Polyakov, A. Y. [National University of Science and Technology MISiS, Leninskiy pr. 4, Moscow 119049 (Russian Federation); Smirnov, N. B. [National University of Science and Technology MISiS, Leninskiy pr. 4, Moscow 119049 (Russian Federation); Institute of Rare Metals, B. Tolmachevsky, 5, Moscow 119017 (Russian Federation); Yakimov, E. B. [National University of Science and Technology MISiS, Leninskiy pr. 4, Moscow 119049 (Russian Federation); Institute of Microelectronics Technology and High Purity Materials, Russian Academy of Science, 6, Academician Ossipyan str., Chernogolovka, Moscow Region 142432 (Russian Federation); Lee, In-Hwan, E-mail: ihlee@jbnu.ac.kr [School of Advanced Materials Engineering and Research Center of Advanced Materials Development, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Pearton, S. J. [University of Florida, Gainesville, Florida 32611 (United States)

2016-01-07

Electrical and luminescent properties and deep trap spectra of Si doped GaN films grown by maskless epitaxial lateral overgrowth (MELO) are reported. The dislocation density in the wing region of the structure was 10{sup 6 }cm{sup −2}, while in the seed region it was 10{sup 8 }cm{sup −2}. The major electron traps present had activation energy of 0.56 eV and concentrations in the high 10{sup 15 }cm{sup −3} range. A comparison of diffusion length values and 0.56 eV trap concentration in MELO GaN and epitaxial lateral overgrowth (ELOG) GaN showed a good correlation, suggesting these traps could be effective in carrier recombination. The doped MELO films were more uniform in their electrical properties than either ELOG films or undoped MELO films. We also discuss the differences in deep trap spectra and luminescence spectra of low-dislocation-density MELO, ELOG, and bulk n-GaN samples grown by hydride vapor phase epitaxy. It is suggested that the observed differences could be caused by the differences in oxygen and carbon contamination levels.

Lateral overgrowth of diamond film on stripes patterned Ir/HPHT-diamond substrate

Science.gov (United States)

Wang, Yan-Feng; Chang, Xiaohui; Liu, Zhangcheng; Liu, Zongchen; Fu, Jiao; Zhao, Dan; Shao, Guoqing; Wang, Juan; Zhang, Shaopeng; Liang, Yan; Zhu, Tianfei; Wang, Wei; Wang, Hong-Xing

2018-05-01

Epitaxial lateral overgrowth (ELO) of diamond films on patterned Ir/(0 0 1)HPHT-diamond substrates have been carried out by microwave plasma CVD system. Ir/(0 0 1)HPHT-diamond substrates are fabricated by photolithographic and magnetron sputtering technique. The morphology of the as grown ELO diamond film is characterized by optical microscopy and scanning electronic microscopy. The quality and stress of the ELO diamond film are investigated by surface etching pit density and micro-Raman spectroscopy. Two ultraviolet photodetectors are fabricated on ELO diamond area and non-ELO diamond area prepared on same substrate, and that one on ELO diamond area indicates better photoelectric properties. All results indicate quality of ELO diamond film is improved.

Improvement of optical quality of semipolar (11 2 ¯ 2 ) GaN on m-plane sapphire by in-situ epitaxial lateral overgrowth

Science.gov (United States)

Monavarian, Morteza; Izyumskaya, Natalia; Müller, Marcus; Metzner, Sebastian; Veit, Peter; Can, Nuri; Das, Saikat; Özgür, Ümit; Bertram, Frank; Christen, Jürgen; Morkoç, Hadis; Avrutin, Vitaliy

2016-04-01

Among the major obstacles for development of non-polar and semipolar GaN structures on foreign substrates are stacking faults which deteriorate the structural and optical quality of the material. In this work, an in-situ SiNx nano-network has been employed to achieve high quality heteroepitaxial semipolar (11 2 ¯ 2 ) GaN on m-plane sapphire with reduced stacking fault density. This approach involves in-situ deposition of a porous SiNx interlayer on GaN that serves as a nano-mask for the subsequent growth, which starts in the nanometer-sized pores (window regions) and then progresses laterally as well, as in the case of conventional epitaxial lateral overgrowth (ELO). The inserted SiNx nano-mask effectively prevents the propagation of defects, such as dislocations and stacking faults, in the growth direction and thus reduces their density in the overgrown layers. The resulting semipolar (11 2 ¯ 2 ) GaN layers exhibit relatively smooth surface morphology and improved optical properties (PL intensity enhanced by a factor of 5 and carrier lifetimes by 35% to 85% compared to the reference semipolar (11 2 ¯ 2 ) GaN layer) which approach to those of the c-plane in-situ nano-ELO GaN reference and, therefore, holds promise for light emitting and detecting devices.

High-quality GaN epitaxially grown on Si substrate with serpentine channels

Science.gov (United States)

Wei, Tiantian; Zong, Hua; Jiang, Shengxiang; Yang, Yue; Liao, Hui; Xie, Yahong; Wang, Wenjie; Li, Junze; Tang, Jun; Hu, Xiaodong

2018-06-01

A novel serpentine-channeled mask was introduced to Si substrate for low-dislocation GaN epitaxial growth and the fully coalesced GaN film on the masked Si substrate was achieved for the first time. Compared with the epitaxial lateral overgrowth (ELOG) growth method, this innovative mask only requires one-step epitaxial growth of GaN which has only one high-dislocation region per mask opening. This new growth method can effectively reduce dislocation density, thus improving the quality of GaN significantly. High-quality GaN with low dislocation density ∼2.4 × 107 cm-2 was obtained, which accounted for about eighty percent of the GaN film in area. This innovative technique is promising for the growth of high-quality GaN templates and the subsequent fabrication of high-performance GaN-based devices like transistors, laser diodes (LDs), and light-emitting diodes (LEDs) on Si substrate.

Malassezia spp. overgrowth in allergic cats.

Science.gov (United States)

Ordeix, Laura; Galeotti, Franca; Scarampella, Fabia; Dedola, Carla; Bardagí, Mar; Romano, Erica; Fondati, Alessandra

2007-10-01

A series of 18 allergic cats with multifocal Malassezia spp. overgrowth is reported: atopic dermatitis was diagnosed in 16, an adverse food reaction in another and one was euthanized 2 months after diagnosis of Malassezia overgrowth. All the cats were otherwise healthy and those tested (16 out of 18) for feline leukaemia or feline immunodeficiency virus infections were all negative. At dermatological examination, multifocal alopecia, erythema, crusting and greasy adherent brownish scales were variably distributed on all cats. Cytological examination revealed Malassezia spp. overgrowth with/without bacterial infection in facial skin (n = 11), ventral neck (n = 6), abdomen (n = 6), ear canal (n = 4), chin (n = 2), ear pinnae (n = 2), interdigital (n = 1) and claw folds skin (n = 1). Moreover, in two cats Malassezia pachydermatis was isolated in fungal cultures from lesional skin. Azoles therapy alone was prescribed in seven, azoles and antibacterial therapy in eight and azoles with both antibacterial and anti-inflammatory therapy in three of the cats. After 3-4 weeks of treatment, substantial reduction of pruritus and skin lesions was observed in all 11 cats treated with a combined therapy and in five of seven treated solely with azoles. Malassezia spp. overgrowth may represent a secondary cutaneous problem in allergic cats particularly in those presented for dermatological examination displaying greasy adherent brownish scales. The favourable response to treatment with antifungal treatments alone suggests that, as in dogs, Malassezia spp. may be partly responsible for both pruritus and cutaneous lesions in allergic cats.

Chronic Inflammatory Gingival Overgrowths: Laser Gingivectomy & Gingivoplasty

OpenAIRE

Shankar, B Shiva; T, Ramadevi; S, Neetha M; Reddy, P Sunil Kumar; Saritha, G; Reddy, J Muralinath

2013-01-01

It is quite common to note chronic inflammatory Gingival overgrowths during and/or post orthodontic treatment. Sometimes the overgrowths may even potentially complicate and/or interrupt orthodontic treatment. With the introduction of soft tissue lasers these problems can now be addressed more easily. Amongst many LASERS now available in Dentistry DIODE LASERS seem to be most ideal for orthodontic soft tissue applications. As newer treatments herald into minimally invasive techniques, DIODE LA...

Matrix metalloproteinase-3 gene polymorphism in renal transplant patients with gingival overgrowth.

Science.gov (United States)

Drozdzik, A; Kurzawski, M; Lener, A; Kozak, M; Banach, J; Drozdzik, M

2010-02-01

Gingival enlargement frequently occurs in transplant patients receiving immunosuppressive drugs. It was hypothesized that gingival enlargement associated with cyclosporine use results from reduced degradation of extracellular matrix in the gingiva. Matrix metalloproteinase-3 (MMP-3) is involved in biodegradation of the extracellular matrix, and its inhibition may contribute to an abnormal accumulation of fibronectin and proteoglycans, which are MMP-3 substrates. The aim of this study was to investigate whether an association exists between MMP-3 genotypes and gingival enlargement in kidney transplant patients medicated with cyclosporine A. Sixty-four unrelated kidney transplant patients suffering from gingival overgrowth, as well as 111 control transplant patients without gingival overgrowth, were enrolled in the study. Gingival overgrowth was assessed 6 mo after transplantation. During the post-transplant period all patients were given cyclosporine A as a principal immunosuppressive agent. MMP-3 polymorphism was determined using a PCR restriction fragment length polymorphism assay. In kidney transplant patients suffering from gingival overgrowth the mean gingival overgrowth score was 1.35 +/- 0.57, whereas in control subjects the mean gingival overgrowth score was 0.0. The distribution of MMP-3-1178A/dupA alleles among all kidney transplant patients, as well as in the two study subgroups, did not differ significantly from Hardy-Weinberg equilibrium. The frequency of the MMP-3-1171A/A genotype (28.1% for gingival overgrowth vs. 26.1% for controls) and of the MMP-3-1171dupA/dupA genotype (32.8% for gingival overgrowth vs. 22.5% for controls) was similar for both study groups. The risk of gingival overgrowth was lowest among patients carrying the MMP-3-1171A/dupA genotype (odds ratio 0.52), but this did not differ markedly from the other genotypes. No association between MMP-3 gene polymorphism and gingival overgrowth was revealed in kidney transplant patients

Subvalvular Pannus Overgrowth after Mosaic Bioprosthesis Implantation in the Aortic Position.

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Hirota, Masanori; Isomura, Tadashi; Yoshida, Minoru; Katsumata, Chieko; Ito, Fusahiko; Watanabe, Masazumi

2016-01-01

Although pannus overgrowth by itself was not the pathology of structural valve deterioration (SVD), it might be related to reoperation for SVD of the bioprostheses. We retrospectively reviewed patients undergoing reoperation for SVD after implantation of the third-generation Mosaic aortic bioprosthesis and macroscopic appearance of the explanted valves was examined to detect the presence of pannus. There were 10 patients and the age for the initial aortic valve replacement was 72 ± 10 years old. The duration of durability was 9.9 ± 2.0 years. Deteriorated valve presented stenosis (valvular area of 0.96 ± 0.20 cm(2); pressure gradient of 60 ± 23 mmHg). Coexisting regurgitant flow was detected in two cases. Macroscopically, subvalvular pannus overgrowth was detected in 8 cases (80%). The proportion of overgrowth from the annulus was almost even and pannus overgrowth created subvalvular membrane, which restricted the area especially for each commissure. In contrast, opening and mobility of each leaflet was not severely limited and pannus overgrowth would restrict the area, especially for each commissure. In other two cases with regurgitation, tear of the leaflet on the stent strut was detected and mild calcification of each leaflet restricted opening. In patients with the Mosaic aortic bioprosthesis, pannus overgrowth was the major cause for reoperation.

Isolated gingival overgrowths: A review of case series

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Shruti Raizada

2016-01-01

Full Text Available Clinicians are often intrigued by the varied manifestations of the gingival tissue. Gingival overgrowth is a common clinical finding and most of them represent a reactive hyperplasia as a direct result of plaque-related inflammatory gingival disease. These types of growth generally respond to good plaque control, removal of the causative irritants, and conservative tissue management. This case series highlights three different cases of localized gingival overgrowth and its management with emphasis on the importance of patient awareness and motivation.

Synthesis of Pd-Au bimetallic nanocrystals via controlled overgrowth.

Science.gov (United States)

Lim, Byungkwon; Kobayashi, Hirokazu; Yu, Taekyung; Wang, Jinguo; Kim, Moon J; Li, Zhi-Yuan; Rycenga, Matthew; Xia, Younan

2010-03-03

This paper describes the synthesis of Pd-Au bimetallic nanocrystals with controlled morphologies via a one-step seeded-growth method. Two different reducing agents, namely, L-ascorbic acid and citric acid, were utilized for the reduction of HAuCl(4) in an aqueous solution to control the overgrowth of Au on cubic Pd seeds. When L-ascorbic acid was used as the reducing agent, conformal overgrowth of Au on the Pd nanocubes led to the formation of Pd-Au nanocrystals with a core-shell structure. On the contrary, localized overgrowth of Au was observed when citric acid was used as the reducing agent, producing Pd-Au bimetallic dimers. Through this morphological control, we were able to tune the localized surface plasmon resonance peaks of Pd-Au bimetallic nanostructures in the visible region.

Petróleo

OpenAIRE

Celso Fernando Lucchesi

1998-01-01

COM MENOS DE 50 anos de atividade empresarialmente organizada a exploração de petróleo no Brasil encontra-se em fase de mudança com a aprovação, em 1997, da nova legislação do setor de petróleo. Descreve-se neste trabalho o período pré-Petrobras (1858 a 1953) e a exclusividade da Petrobras (1954 a 1997) que resultou no expressivo volume de reservas de petróleo no país, da ordem de 17 bilhões de barris de óleo equivalente no final de 1997. Projetos de produção já iniciados elevarão a produção ...

Size and shape control in the overgrowth of gold nanorods

International Nuclear Information System (INIS)

Ratto, Fulvio; Matteini, Paolo; Rossi, Francesca; Pini, Roberto

2010-01-01

We report on a new sustainable approach to manipulate the optical behaviour and geometrical properties of gold nanorods in aqueous solutions by fine control of their overgrowth. In our approach, the overgrowth is realized by modulation of the reduction of the gold ions which are left as Au 1+ after the primary step of the synthesis (typically as much as ∼80% of the gold ions available in the growth solution). The progress of the reduction requires the gradual addition of ascorbic acid, which transforms the Au 1+ into Au 0 and may be performed in the original growth solution with no need for any further manipulation. By control of the total amount and rate of administration of the ascorbic acid, we prove the possibility to realize a systematic modulation of the average lengths, diameters, shapes (rod or dog-bone like), and light extinction of the nanoparticles. A slow overgrowth leads to a gradual enlargement of the lengths and diameters at almost constant shape. In contrast, a faster overgrowth results into a more complex modification of the overall shape of the gold nanorods.

Overgrowth of the limbs: A prospective study of 21 Ghanaian patients

African Journals Online (AJOL)

Introduction: Overgrowth or gigantism is a congenital enlargement of the soft tissue parts of a limb often with associated enlargement of the skeleton, due to overgrowth of one or more cell types. It may be associated with lipofibromatosis, neurofibromatosis, hyperostosis, or hemihypertrophy. Extent of the burden is unknown ...

CLOVES syndrome: review of a PIK3CA-related overgrowth spectrum (PROS).

Science.gov (United States)

Martinez-Lopez, A; Blasco-Morente, G; Perez-Lopez, I; Herrera-Garcia, J D; Luque-Valenzuela, M; Sanchez-Cano, D; Lopez-Gutierrez, J C; Ruiz-Villaverde, R; Tercedor-Sanchez, J

2017-01-01

Overgrowth syndromes are characterized by global or localized disproportionate growth associated with other anomalies, including vascular malformations and neurological and/or visceral disorders. CLOVES (Congenital Lipomatous asymmetric Overgrowth of the trunk with lymphatic, capillary, venous, and combined-type Vascular malformations, Epidermal naevi, Scoliosis/Skeletal and spinal anomalies) is an overgrowth syndrome caused by mosaic activating mutation in gene PIK3CA, which gives rise to abnormal PI3K-AKT-mTOR pathway activation. These mutations are responsible for the clinical manifestations of the syndrome, which include low- and high-flow vascular malformations, thoracic lipomatous hyperplasia, asymmetric growth, and visceral and neurological disorders. These common anomalies are illustrated with figures from two personal cases. Identification of the clinical and genetic characteristics of CLOVES syndrome is crucial for the differential diagnosis with other overgrowth syndromes, such as Proteus or Klippel-Trenaunay (K-T) syndromes, and for the therapeutic management of the different anomalies. In this context, a new entity comprising different syndromes with phenotypic mutations in PIK3CA has been proposed, designated PIK3CA-related overgrowth spectrum (PROS), with the aim of facilitating clinical management and establishing appropriate genetic study criteria. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Effect of concomitant administration of nifedipine and tacrolimus on the development of gingival overgrowth in rats

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Sheng-Yi Chen

2015-03-01

Conclusion: Gingival overgrowth could be induced either by nifedipine or by tacrolimus, although the extent of gingival overgrowth induced by tacrolimus would be less than that by nifedipine. However, a concomitant administration of nifedipine and tacrolimus did not aggravate the induced gingival overgrowth.

Mutations in the DNA methyltransferase gene DNMT3A cause an overgrowth syndrome with intellectual disability

DEFF Research Database (Denmark)

Tatton-Brown, Katrina; Seal, Sheila; Ruark, Elise

2014-01-01

Overgrowth disorders are a heterogeneous group of conditions characterized by increased growth parameters and other variable clinical features such as intellectual disability and facial dysmorphism. To identify new causes of human overgrowth, we performed exome sequencing in ten proband-parent tr......Overgrowth disorders are a heterogeneous group of conditions characterized by increased growth parameters and other variable clinical features such as intellectual disability and facial dysmorphism. To identify new causes of human overgrowth, we performed exome sequencing in ten proband...

Nonsurgical Management of Nifedipine Induced Gingival Overgrowth

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George Sam

2014-01-01

Full Text Available Drug-induced gingival overgrowth is frequently associated with three particular drugs: phenytoin, cyclosporin, and nifedipine. As gingival enlargement develops, it affects the normal oral hygiene practice and may interfere with masticatory functions. The awareness in the medical community about this possible side effect of nifedipine is less when compared to the effects of phenytoin and cyclosporin. The frequency of gingival enlargement associated with chronic nifedipine therapy remains controversial. Within the group of patients that develop this unwanted effect, there appears to be variability in the extent and severity of the gingival changes. Although gingival inflammation is considered a primary requisite in their development, few cases with minimal or no plaque induced gingival inflammation have also been reported. A case report of gingival overgrowth induced by nifedipine in a patient with good oral hygiene and its nonsurgical management with drug substitution is discussed in this case report.

PREVALENCE OF SMALL INTESTINE BACTERIAL OVERGROWTH IN PATIENTS WITH GASTROINTESTINAL SYMPTOMS

OpenAIRE

MARTINS, Carolina Piedade; CHAVES, Caio Henrique Amorim; CASTRO, Maurício Gustavo Bravim de; GOMES, Isabel Cristina; PASSOS, Maria do Carmo Friche

2017-01-01

ABSTRACT BACKGROUND Small intestine bacterial overgrowth is a heterogeneous syndrome characterized by an increase in the number and/or the presence of atypical microbiota in the small intestine. The symptoms of small intestine bacterial overgrowth are unspecific, encompassing abdominal pain/distension, diarrhea and flatulence. Due to the increased cost and complexity for carrying out the jejunal aspirate, the gold standard for diagnosis of the syndrome, routinely the hydrogen (H 2 ) breath t...

Pannus overgrowth after mitral valve replacement with a Carpentier-Edwards pericardial bioprosthesis.

Science.gov (United States)

Oda, Takeshi; Kato, Seiya; Tayama, Eiki; Fukunaga, Shuji; Akashi, Hidetoshi; Aoyagi, Shigeaki

2009-01-01

A Carpentier-Edwards pericardial (CEP) bioprosthesis was explanted from an 81-year-old woman due to nonstructural dysfunction 9 years after mitral valve replacement. The nonstructural dysfunction produced severe regurgitation in the mitral position. During the surgery, excessive pannus overgrowth was seen on the left ventricular side of the CEP bioprosthesis. Pannus overgrowth was prominent on one leaflet. That leaflet was stiff and shortened due to the excessive overgrowth of pannus. In this patient, the distortion of one leaflet was the main reason for transvalvular leakage of the CEP bioprosthesis in the mitral position. A new CEP bioprosthesis was implanted in the mitral position. Pathological analysis revealed fibrotic pannus with a small amount of cellular material over the leaflets of the resected CEP valve. This change was marked on the distorted leaflet.

Wholesale debris removal from LEO

Science.gov (United States)

Levin, Eugene; Pearson, Jerome; Carroll, Joseph

2012-04-01

Recent advances in electrodynamic propulsion make it possible to seriously consider wholesale removal of large debris from LEO for the first time since the beginning of the space era. Cumulative ranking of large groups of the LEO debris population and general limitations of passive drag devices and rocket-based removal systems are analyzed. A candidate electrodynamic debris removal system is discussed that can affordably remove all debris objects over 2 kg from LEO in 7 years. That means removing more than 99% of the collision-generated debris potential in LEO. Removal is performed by a dozen 100-kg propellantless vehicles that react against the Earth's magnetic field. The debris objects are dragged down and released into short-lived orbits below ISS. As an alternative to deorbit, some of them can be collected for storage and possible in-orbit recycling. The estimated cost per kilogram of debris removed is a small fraction of typical launch costs per kilogram. These rates are low enough to open commercial opportunities and create a governing framework for wholesale removal of large debris objects from LEO.

PREVALENCE OF SMALL INTESTINE BACTERIAL OVERGROWTH IN PATIENTS WITH GASTROINTESTINAL SYMPTOMS

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Carolina Piedade MARTINS

2017-02-01

Full Text Available ABSTRACT BACKGROUND Small intestine bacterial overgrowth is a heterogeneous syndrome characterized by an increase in the number and/or the presence of atypical microbiota in the small intestine. The symptoms of small intestine bacterial overgrowth are unspecific, encompassing abdominal pain/distension, diarrhea and flatulence. Due to the increased cost and complexity for carrying out the jejunal aspirate, the gold standard for diagnosis of the syndrome, routinely the hydrogen (H 2 breath test has been used, utilizing glucose or lactulose as substrate, which is able to determine, in the exhaled air, the H 2 concentration produced from the intestinal bacterial metabolism. However, due to a number of individuals presenting a methanogenic microbiota, which does not produce H 2 , the testing on devices capable of detecting, concurrently, the concentration of exhaled H 2 and methane (CH 4 is justified. OBJECTIVE This study aimed to determine the prevalence of small intestine bacterial overgrowth in patients with digestive symptoms, through a comparative analysis of breath tests of H 2 or H 2 and CH 4 associated, using glucose as substrate . METHODS A total of 200 patients of both sexes without age limitation were evaluated, being directed to a Breath Test Laboratory for performing the H 2 test (100 patients and of exhaled H 2 and CH 4 (100 patients due to gastrointestinal complaints, most of them patients with gastrointestinal functional disorders. RESULTS The results indicated a significant prevalence of small intestine bacterial overgrowth in the H 2 test and in the test of exhaled H 2 and CH 4 (56% and 64% respectively in patients with gastrointestinal symptoms, and higher prevalence in females. It found further that methane gas was alone responsible for positivity in 18% of patients. CONCLUSION The data found in this study is consistent with the findings of the current literature and underscores the need for using devices capable of capturing the

Mitochondrial genome of the African lion Panthera leo leo.

Science.gov (United States)

Ma, Yue-ping; Wang, Shuo

2015-01-01

In this study, the complete mitochondrial genome sequence of the African lion P. leo leo was reported. The total length of the mitogenome was 17,054 bp. It contained the typical mitochondrial structure, including 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and 1 control region; 21 of the tRNA genes folded into typical cloverleaf secondary structure except for tRNASe. The overall composition of the mitogenome was A (32.0%), G (14.5%), C (26.5%) and T (27.0%). The new sequence will provide molecular genetic information for conservation genetics study of this important large carnivore.

Auger line shape changes in epitaxial (111)Pd/(111)Cu films

Energy Technology Data Exchange (ETDEWEB)

Chao, S S; Knabbe, E A; Vook, R W

1980-01-01

Epitaxial Pd films ranging in thickness from a few tenths of a monolayer up to many monolayers were formed on (111)Cu substrate films at room temperature under uhv conditions. The growth of these Pd films was monitored in situ by Auger electron spectroscopy. The line profiles of the Cu MMM (61 eV) and Pd MVV (329 eV) AES doublets varied significantly with the amount of Pd deposited. A new measure of the AES doublet line profile, called the R-factor, was defined. A graph of R/sub Pd/ versus Pd film thickness shows a sharp decline with increasing thickness. Superimposed on the major trends is a cyclical variation. A corresponding periodicity in R/sub Cu/ was observed for the Cu MMM (61 eV) AES doublet. The results suggest that the R-factor provides a direct measure of changes in the electronic structures of the overgrowth and substrate films as the former thickens by a layer-growth mechanism.

Immunoexpression of interleukin-6 in drug-induced gingival overgrowth patients

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P R Ganesh

2016-01-01

Full Text Available Background: To analyze the role of proinflammatory cytokines in drug-induced gingival enlargement in Indian population. Aim: To evaluate for the presence of interleukin-6 (IL-6 in drug-induced gingival enlargement and to compare it with healthy control in the absence of enlargement. Materials and Methods: Thirty-five patients selected for the study and divided into control group (10 and study group (25 consisting of phenytoin (10; cyclosporin (10 and nifedipine (5 induced gingival enlargement. Gingival overgrowth index of Seymour was used to assess overgrowth and allot groups. Under LA, incisional biopsy done, tissue sample fixed in 10% formalin and immunohistochemically evaluated for the presence of IL-6 using LAB-SA method, Labeled- Streptavidin-Biotin Method (LAB-SA kit from Zymed- 2nd generation LAB-SA detection system, Zymed Laboratories, CA. The results of immunohistochemistry were statistically analyzed using Kruskaal–Wallis and Mann–Whitney test. Results: The data obtained from immunohistochemistry assessment shows that drug-induced gingival overgrowth (DIGO samples express more IL-6 than control group and cyclosporin expresses more IL-6 followed by phenytoin and nifedipine. Conclusion: Increased IL-6 expression was noticed in all three DIGO groups in comparison with control group. Among the study group, cyclosporin expressed maximum IL-6 expression followed by phenytoin and nifedipine.

Trends in heteroepitaxy of III-Vs on silicon for photonic and photovoltaic applications

Science.gov (United States)

Lourdudoss, Sebastian; Junesand, Carl; Kataria, Himanshu; Metaferia, Wondwosen; Omanakuttan, Giriprasanth; Sun, Yan-Ting; Wang, Zhechao; Olsson, Fredrik

2017-02-01

We present and compare the existing methods of heteroepitaxy of III-Vs on silicon and their trends. We focus on the epitaxial lateral overgrowth (ELOG) method as a means of achieving good quality III-Vs on silicon. Initially conducted primarily by near-equilibrium epitaxial methods such as liquid phase epitaxy and hydride vapour phase epitaxy, nowadays ELOG is being carried out even by non-equilibrium methods such as metal organic vapour phase epitaxy. In the ELOG method, the intermediate defective seed and the mask layers still exist between the laterally grown purer III-V layer and silicon. In a modified ELOG method called corrugated epitaxial lateral overgrowth (CELOG) method, it is possible to obtain direct interface between the III-V layer and silicon. In this presentation we exemplify some recent results obtained by these techniques. We assess the potentials of these methods along with the other existing methods for realizing truly monolithic photonic integration on silicon and III-V/Si heterojunction solar cells.

Can chlorhexidine mouthwash twice daily ameliorate cyclosporine-induced gingival overgrowth?

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Ching-Hwa Gau

2013-03-01

Conclusion: These findings suggest that chlorhexidine mouthwash used twice daily may reduce the severity of CsA-induced gingival overgrowth. Further research is warranted to determine the optimal dose and treatment regimen.

Gengibre (zingiber officinale roscoe brasileiro: aspectos gerais, óleo essencial e oleoresina. parte 2 - secagem, óleo essencial e oleoresina

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Mauro Taveira Magalhães

1997-08-01

Full Text Available A partir de amostras de gengibre (Zingiber officinale Roscoe do tipo "Gigante", oriundas das diversas localidades produtoras do Brasil, procurou-se estabelecer as melhores condições de processamento e verificar a qualidade do óleo essencial e da oleoresina obtidos. A composição do óleo essencial de gengibre gigante varia de acordo com a técnica de extração e o estado do rizoma. Os óleos essenciais de rizomas frescos e secos foram comparados através de seus índices físico-químicos e composição por CG. São apresentadas as características do óleo essencial do rizoma seco obtido por arraste direto a vapor. Nas oleoresinas obtidas com diferentes solventes determinou-se o teor de óleo essencial. O gengibre comercial brasileiro fornece óleo essencial num rendimento de 2,2% e oleoresina em rendimentos que variam de 6,91-10,90% (etanol, 2,53-5,62% (acetona e 3,35-3,91% (dicloroetano, sendo alternativas interessantes de utilização.

Leo

Science.gov (United States)

Murdin, P.

2000-11-01

(the Lion; abbrev. Leo, gen. Leonis; area 947 sq. deg.) A northern zodiacal constellation which lies between Cancer and Virgo, and culminates at midnight in early March. It represents the Nemean lion that, in Greek mythology, Hercules killed as the first of his 12 labors. Its brightest stars were cataloged by Ptolemy (c. AD 100-175) in the Almagest....

«Somos petróleo»

OpenAIRE

Drum, Duskin

2017-01-01

Resumen «Somos petróleo» es un experimento de práctica-como-investigación creado para indagar sobre la manera como los norteamericanos conceptualizan sus relaciones con el petróleo. Durante el performance los participantes leyeron en voz alta emulaciones del testimonio diplomático Gwich'in sobre ser pueblo caribú. En las emulaciones, el texto es el mismo salvo que se reemplaza la palabra «caribú» por «petróleo». Los Gwich'in son un pueblo indígena cuyas tierras de origen se sitúan en el nores...

Petróleo

Directory of Open Access Journals (Sweden)

Celso Fernando Lucchesi

1998-08-01

Full Text Available COM MENOS DE 50 anos de atividade empresarialmente organizada a exploração de petróleo no Brasil encontra-se em fase de mudança com a aprovação, em 1997, da nova legislação do setor de petróleo. Descreve-se neste trabalho o período pré-Petrobras (1858 a 1953 e a exclusividade da Petrobras (1954 a 1997 que resultou no expressivo volume de reservas de petróleo no país, da ordem de 17 bilhões de barris de óleo equivalente no final de 1997. Projetos de produção já iniciados elevarão a produção a mais de 1,5 milhão de barris de óleo por dia no início do novo século. O gás natural crescerá rapidamente sua participação na matriz energética a partir de 1999. Com a instalação da Agência Nacional de Petróleo (ANP inicia-se uma nova fase, sendo esta responsável pela atração de novos investimentos na busca de novas reservas nas bacias sedimentares brasileiras, cujo potencial é ainda significativo. Diversas empresas internacionais deverão estar operando no país no curto prazo, inicialmente associadas à Petrobras. O modelo adotado para as atividades de exploração e produção no país é o de concessão. A atividade no Brasil nesta área dependerá do regime fiscal que vier a ser implantado.THE APPROVAL OF the new Petroleum Law in 1997 proposed a dramatic change in the activities of petroleum exploration in Brazil after almost fifty years of its initial entrepreneurual organization, represented by the creation of Petrobras, in 1953. In this work two important periods are described: the pre-Petrobras period (1858 to 1953 and the period when Petrobras acted alone in the oil business (1954 to 1997. During the last one, significant results were achieved. The amount of reserves reached 17 billion barrels of oil equivalent and were made available to the country at the end of 1997. Production projects already in place or under development will raise Brazilian daily production to levels of 1.5 million barrels of oil per day

Mactosylceramide Prevents Glial Cell Overgrowth by Inhibiting Insulin and Fibroblast Growth Factor Receptor Signaling

DEFF Research Database (Denmark)

Gerdøe-Kristensen, Stine; Lund, Viktor K; Wandall, Hans H

2017-01-01

, in which the mannosyltransferase Egghead controls conversion of glucosylceramide (GlcCer) to mactosylceramide (MacCer). Lack of elongated GSL in egghead (egh) mutants causes overgrowth of subperineurial glia (SPG), largely due to aberrant activation of phosphatidylinositol 3-kinase (PI3K). However, to what...... of the Drosophila Insulin Receptor (InR) and the FGFR homolog Heartless (Htl) in wild type SPG, and is suppressed by inhibiting Htl and InR activity in egh. Knockdown of GlcCer synthase in the SPG fails to suppress glial overgrowth in egh nerves, and slightly promotes overgrowth in wild type, suggesting that RTK...... hyperactivation is caused by absence of MacCer and not by GlcCer accumulation. We conclude that an early product in GSL biosynthesis, MacCer, prevents inappropriate activation of Insulin and Fibroblast Growth Factor Receptors in Drosophila glia. This article is protected by copyright. All rights reserved....

Pumping requirements and options for molecular beam epitaxy and gas source molecular beam epitaxy/chemical beam epitaxy

International Nuclear Information System (INIS)

McCollum, M.J.; Plano, M.A.; Haase, M.A.; Robbins, V.M.; Jackson, S.L.; Cheng, K.Y.; Stillman, G.E.

1989-01-01

This paper discusses the use of gas sources in growth by MBE as a result of current interest in growth of InP/InGaAsP/InGaAs lattice matched to InP. For gas flows greater than a few sccm, pumping speed requirements dictate the use of turbomolecular or diffusion pumps. GaAs samples with high p-type mobilities have been grown with diffusion pumped molecular beam epitaxial system. According to the authors, this demonstration of the inherent cleanliness of a properly designed diffusion pumping system indicates that a diffusion pump is an excellent inexpensive and reliable choice for growth by molecular beam epitaxy and gas source molecular beam epitaxy/chemical beam epitaxy

Dislocation reduction in heteroepitaxial Ge on Si using SiO{sub 2} lined etch pits and epitaxial lateral overgrowth

Energy Technology Data Exchange (ETDEWEB)

Leonhardt, Darin; Han, Sang M. [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

2011-09-12

We report a technique that significantly reduces threading dislocations in Ge on Si heteroepitaxy. Germanium is first grown on Si and etched to produce pits in the surface where threading dislocations terminate. Further processing leaves a layer of SiO{sub 2} only within etch pits. Subsequent selective epitaxial Ge growth results in coalescence above the SiO{sub 2}. The SiO{sub 2} blocks the threading dislocations from propagating into the upper Ge epilayer. With annealed Ge films grown on Si, the said method reduces the defect density from 2.6 x 10{sup 8} to 1.7 x 10{sup 6} cm{sup -2}, potentially making the layer suitable for electronic and photovoltaic devices.

GaAs structures with InAs and As quantum dots produced in a single molecular beam epitaxy process

International Nuclear Information System (INIS)

Nevedomskii, V. N.; Bert, N. A.; Chaldyshev, V. V.; Preobrazhenskii, V. V.; Putyato, M. A.; Semyagin, B. R.

2009-01-01

Epitaxial GaAs layers containing InAs semiconductor quantum dots and As metal quantum dots are grown by molecular beam epitaxy. The InAs quantum dots are formed by the Stranskii-Krastanow mechanism, whereas the As quantum dots are self-assembled in the GaAs layer grown at low temperature with a large As excess. The microstructure of the samples is studied by transmission electron microscopy. It is established that the As metal quantum dots formed in the immediate vicinity of the InAs semiconductor quantum dots are larger in size than the As quantum dots formed far from the InAs quantum dots. This is apparently due to the effect of strain fields of the InAs quantum dots upon the self-assembling of As quantum dots. Another phenomenon apparently associated with local strains around the InAs quantum dots is the formation of V-like defects (stacking faults) during the overgrowth of the InAs quantum dots with the GaAs layer by low-temperature molecular beam epitaxy. Such defects have a profound effect on the self-assembling of As quantum dots. Specifically, on high-temperature annealing needed for the formation of large-sized As quantum dots by Ostwald ripening, the V-like defects bring about the dissolution of the As quantum dots in the vicinity of the defects. In this case, excess arsenic most probably diffuses towards the open surface of the sample via the channels of accelerated diffusion in the planes of stacking faults.

LEO P: AN UNQUENCHED VERY LOW-MASS GALAXY

International Nuclear Information System (INIS)

McQuinn, Kristen B. W.; Skillman, Evan D.; Berg, Danielle; Dolphin, Andrew; Cannon, John M.; Salzer, John J.; Rhode, Katherine L.; Adams, Elizabeth A. K.; Giovanelli, Riccardo; Haynes, Martha P.; Girardi, Léo

2015-01-01

Leo P is a low-luminosity dwarf galaxy discovered through the blind H i Arecibo Legacy Fast ALFA survey. The H i and follow-up optical observations have shown that Leo P is a gas-rich dwarf galaxy with active star formation, an underlying older population, and an extremely low oxygen abundance. We have obtained optical imaging with the Hubble Space Telescope to two magnitudes below the red clump in order to study the evolution of Leo P. We refine the distance measurement to Leo P to be 1.62 ± 0.15 Mpc, based on the luminosity of the horizontal branch stars and 10 newly identified RR Lyrae candidates. This places the galaxy at the edge of the Local Group, ∼0.4 Mpc from Sextans B, the nearest galaxy in the NGC 3109 association of dwarf galaxies of which Leo P is clearly a member. The star responsible for ionizing the H ii region is most likely an O7V or O8V spectral type, with a stellar mass ≳25 M ⊙ . The presence of this star provides observational evidence that massive stars at the upper end of the initial mass function are capable of being formed at star formation rates as low as ∼10 −5 M ⊙ yr −1 . The best-fitting star formation history (SFH) derived from the resolved stellar populations of Leo P using the latest PARSEC models shows a relatively constant star formation rate over the lifetime of the galaxy. The modeled luminosity characteristics of Leo P at early times are consistent with low-luminosity dSph Milky Way satellites, suggesting that Leo P is what a low-mass dSph would look like if it evolved in isolation and retained its gas. Despite the very low mass of Leo P, the imprint of reionization on its SFH is subtle at best, and consistent with being totally negligible. The isolation of Leo P, and the total quenching of star formation of Milky Way satellites of similar mass, implies that the local environment dominates the quenching of the Milky Way satellites

LEO P: AN UNQUENCHED VERY LOW-MASS GALAXY

Energy Technology Data Exchange (ETDEWEB)

McQuinn, Kristen B. W.; Skillman, Evan D.; Berg, Danielle [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street, S.E., University of Minnesota, Minneapolis, MN 55455 (United States); Dolphin, Andrew [Raytheon Company, 1151 E. Hermans Road, Tucson, AZ 85756 (United States); Cannon, John M. [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); Salzer, John J.; Rhode, Katherine L. [Department of Astronomy, Indiana University, 727 East 3rd Street, Bloomington, IN 47405 (United States); Adams, Elizabeth A. K. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Giovanelli, Riccardo; Haynes, Martha P. [Center for Radiophysics and Space Research, Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States); Girardi, Léo, E-mail: kmcquinn@astro.umn.edu [Osservatorio Astronomico di Padova, INAF, Vicolo dell’Osservatorio 5, I-35122 Padova (Italy)

2015-10-20

Leo P is a low-luminosity dwarf galaxy discovered through the blind H i Arecibo Legacy Fast ALFA survey. The H i and follow-up optical observations have shown that Leo P is a gas-rich dwarf galaxy with active star formation, an underlying older population, and an extremely low oxygen abundance. We have obtained optical imaging with the Hubble Space Telescope to two magnitudes below the red clump in order to study the evolution of Leo P. We refine the distance measurement to Leo P to be 1.62 ± 0.15 Mpc, based on the luminosity of the horizontal branch stars and 10 newly identified RR Lyrae candidates. This places the galaxy at the edge of the Local Group, ∼0.4 Mpc from Sextans B, the nearest galaxy in the NGC 3109 association of dwarf galaxies of which Leo P is clearly a member. The star responsible for ionizing the H ii region is most likely an O7V or O8V spectral type, with a stellar mass ≳25 M{sub ⊙}. The presence of this star provides observational evidence that massive stars at the upper end of the initial mass function are capable of being formed at star formation rates as low as ∼10{sup −5} M{sub ⊙} yr{sup −1}. The best-fitting star formation history (SFH) derived from the resolved stellar populations of Leo P using the latest PARSEC models shows a relatively constant star formation rate over the lifetime of the galaxy. The modeled luminosity characteristics of Leo P at early times are consistent with low-luminosity dSph Milky Way satellites, suggesting that Leo P is what a low-mass dSph would look like if it evolved in isolation and retained its gas. Despite the very low mass of Leo P, the imprint of reionization on its SFH is subtle at best, and consistent with being totally negligible. The isolation of Leo P, and the total quenching of star formation of Milky Way satellites of similar mass, implies that the local environment dominates the quenching of the Milky Way satellites.

Mitral stenosis due to pannus overgrowth after rigid ring annuloplasty.

Science.gov (United States)

Oda, Takeshi; Kato, Seiya; Tayama, Eiki; Fukunaga, Shuji; Akashi, Hidetoshi; Aoyagi, Shigeaki

2010-03-01

Although mitral stenosis (MS) due to pannus overgrowth after mitral valve repair for rheumatic mitral regurgitation (MR) is not uncommon, it is extremely rare in relation to non-rheumatic mitral regurgitation. Whilst it has been suggested that the rigid annuloplasty ring induces pannus overgrowth in the same manner as the flexible ring, to date only in cases using the flexible ring has pannus formation been confirmed by a pathological examination after redo surgery. The case is described of a woman who had undergone mitral valve repair using a 28 mm rigid ring three years previously because of non-rheumatic MR, and subsequently suffered from MS due to pannus formation over the annuloplasty ring. To the present authors' knowledge, this is the first report of MS due to pannus formation after mitral valve repair using a rigid annuloplasty ring to treat non-rheumatic MR documented at reoperation.

Leo Satellite Communication through a LEO Constellation using TCP/IP Over ATM

Science.gov (United States)

Foore, Lawrence R.; Konangi, Vijay K.; Wallett, Thomas M.

1999-01-01

The simulated performance characteristics for communication between a terrestrial client and a Low Earth Orbit (LEO) satellite server are presented. The client and server nodes consist of a Transmission Control Protocol /Internet Protocol (TCP/IP) over ATM configuration. The ATM cells from the client or the server are transmitted to a gateway, packaged with some header information and transferred to a commercial LEO satellite constellation. These cells are then routed through the constellation to a gateway on the globe that allows the client/server communication to take place. Unspecified Bit Rate (UBR) is specified as the quality of service (QoS). Various data rates are considered.

Efficacy of AZM therapy in patients with gingival overgrowth induced by Cyclosporine A: a systematic review

Directory of Open Access Journals (Sweden)

Deli Giorgio

2008-12-01

Full Text Available Abstract Background In daily clinical practice of a dental department it's common to find gingival overgrowth (GO in periodontal patients under treatment with Cyclosporine A (CsA. The pathogenesis of GO and the mechanism of action of Azithromycin (AZM are unclear. A systematic review was conducted in order to evaluate the efficacy of Azithromycin in patients with gingival overgrowth induced by assumption of Cyclosporine A. Methods A bibliographic search was performed using the online databases MEDLINE, EMBASE and Cochrane Central of Register Controlled Trials (CENTRAL in the time period between 1966 and September 2008. Results The literature search retrieved 24 articles; only 5 were Randomised Controlled Trials (RCTs, published in English, fulfilled the inclusion criteria. A great heterogeneity between proposed treatments and outcomes was found, and this did not allow to conduct a quantitative meta-analysis. The systematic review revealed that a 5-day course of Azithromycin with Scaling and Root Planing reduces the degree of gingival overgrowth, while a 7-day course of metronidazole is only effective on concomitant bacterial over-infection. Conclusion Few RCTs on the efficacy of systemic antibiotic therapy in case of GO were found in the literature review. A systemic antibiotic therapy without plaque and calculus removal is not able to reduce gingival overgrowth. The great heterogeneity of diagnostic data and outcomes is due to the lack of precise diagnostic methods and protocols about GO. Future studies need to improve both diagnostic methods and tools and adequate classification aimed to determine a correct prognosis and an appropriate therapy for gingival overgrowth.

Epitaxial graphene

Science.gov (United States)

de Heer, Walt A.; Berger, Claire; Wu, Xiaosong; First, Phillip N.; Conrad, Edward H.; Li, Xuebin; Li, Tianbo; Sprinkle, Michael; Hass, Joanna; Sadowski, Marcin L.; Potemski, Marek; Martinez, Gérard

2007-07-01

Graphene multilayers are grown epitaxially on single crystal silicon carbide. This system is composed of several graphene layers of which the first layer is electron doped due to the built-in electric field and the other layers are essentially undoped. Unlike graphite the charge carriers show Dirac particle properties (i.e. an anomalous Berry's phase, weak anti-localization and square root field dependence of the Landau level energies). Epitaxial graphene shows quasi-ballistic transport and long coherence lengths; properties that may persist above cryogenic temperatures. Paradoxically, in contrast to exfoliated graphene, the quantum Hall effect is not observed in high-mobility epitaxial graphene. It appears that the effect is suppressed due to the absence of localized states in the bulk of the material. Epitaxial graphene can be patterned using standard lithography methods and characterized using a wide array of techniques. These favorable features indicate that interconnected room temperature ballistic devices may be feasible for low-dissipation high-speed nanoelectronics.

Introducing Leo LT - the "three-headed lion"

Index Scriptorium Estoniae

2008-01-01

Leedu valitsus kiitis heaks seaduseparandused, mille tulemusena saab võtta tuumajaama ehitaja, investeerimis- ja energiafirma Leo LT strateegilise tähtsusega firmade hulka. Kui parlament valitsuse ettepanekud heaks kiidab, saab riik 61,7% Leo LT ja 38,3% NDX Energija aktsiatest

GENERAL OVERGROWTH IN THE FRAGILE-X SYNDROME - VARIABILITY IN THE PHENOTYPIC-EXPRESSION OF THE FMR1 GENE MUTATION

NARCIS (Netherlands)

DEVRIES, BBA; ROBINSON, H; STOLTEDIJKSTRA, [No Value; GI, CVTP; DIJKSTRA, PF; VANDOOM, J; HALLEY, DJJ; OOSTRA, BA; TURNER, G; NIERMEIJER, MF

1995-01-01

The fragile X syndrome, which often presents in childhood with overgrowth, may in some cases show some diagnostic overlap with classical Sotos syndrome. We describe four fragile X patients with general overgrowth, all of whom are from families with other affected relatives who show the classic

Leo II PC

Data.gov (United States)

Kansas Data Access and Support Center — LEO II is a second-generation software system developed for use on the PC, which is designed to convert location references accurately between legal descriptions and...

Determinants of gingival overgrowth severity in organ transplant patients. An examination of the rôle of HLA phenotype.

Science.gov (United States)

Thomason, J M; Seymour, R A; Ellis, J S; Kelly, P J; Parry, G; Dark, J; Wilkinson, R; Ilde, J R

1996-07-01

The role of HLA phenotype as a risk factor for drug-induced gingival overgrowth was investigated in a cohort of 172 transplant recipients. Clinically significant overgrowth warranting surgical correction was observed in 72 patients (42%). Using stepwise regression modelling, 6 clinical parameters were identified as significant risk factors for the severity of gingival overgrowth. These were; age, sex, creatinine plasma level, duration of therapy, papilla bleeding index and concomitant medication with a calcium channel blocking drug. 3 HLA alleles were also identified as risk factors when adjusted for other clinically significant risk factors (HLA -DR2, A24, B37). However, when the p-values for the HLA variables were corrected to compensate for the use of multiple significance testing, only HLA-B37 remained statistically significant at the 5% level. Organ transplant patients are at risk of developing gingival overgrowth, with approximately 25% medicated with cyclosporin alone requiring corrective gingival surgery. This figure more than doubles in patients concomitantly medicated with a calcium blocking drug. The data at present available would suggest that the severity of gingival overgrowth is also significantly associated with the HLA-B37 phenotype.

Epitaxy physical principles and technical implementation

CERN Document Server

Herman, Marian A; Sitter, Helmut

2004-01-01

Epitaxy provides readers with a comprehensive treatment of the modern models and modifications of epitaxy, together with the relevant experimental and technological framework. This advanced textbook describes all important aspects of the epitaxial growth processes of solid films on crystalline substrates, including a section on heteroepitaxy. It covers and discusses in details the most important epitaxial growth techniques, which are currently widely used in basic research as well as in manufacturing processes of devices, namely solid-phase epitaxy, liquid-phase epitaxy, vapor-phase epitaxy, including metal-organic vapor-phase epitaxy and molecular-beam epitaxy. Epitaxy’s coverage of science and texhnology thin-film is intended to fill the need for a comprehensive reference and text examining the variety of problems related to the physical foundations and technical implementation of epitaxial crystallization. It is intended for undergraduate students, PhD students, research scientists, lecturers and practic...

Small intestinal bacterial overgrowth prevalence in celiac disease patients is similar in healthy subjects and lower in irritable bowel syndrome patients.

Science.gov (United States)

Lasa, J S; Zubiaurre, I; Fanjul, I; Olivera, P; Soifer, L

2015-01-01

Untreated celiac disease has traditionally been linked to a greater risk for small intestinal bacterial overgrowth, but the existing evidence is inconclusive. To compare the prevalence of small intestinal bacterial overgrowth in subjects with celiac disease compared with control subjects and patients with irritable bowel syndrome. The study included 15 untreated celiac disease patients, 15 subjects with irritable bowel syndrome, and 15 healthy controls. All enrolled patients underwent a lactulose breath test measuring hydrogen and methane. Small intestinal bacterial overgrowth was defined according to previously published criteria. No differences were found in relation to age or sex. The prevalence of small intestinal bacterial overgrowth was similar between the celiac disease patients and the controls (20 vs. 13.33%, P=NS), whereas it was higher in patients with irritable bowel syndrome (66.66%, Pintestinal bacterial overgrowth between the untreated celiac disease patients and healthy controls. Copyright © 2015 Asociación Mexicana de Gastroenterología. Published by Masson Doyma México S.A. All rights reserved.

The Resolved Stellar Population of Leo A

Science.gov (United States)

Tolstoy, Eline

1996-05-01

New observations of the resolved stellar population of the extremely metal-poor Magellanic dwarf irregular galaxy Leo A in Thuan-Gunn r, g, i, and narrowband Hα filters are presented. Using the recent Cepheid variable star distance determination to Leo A by Hoessel et al., we are able to create an accurate color-magnitude diagram (CMD). We have used the Bavesian inference method described by Tolstoy & Saha to calculate the likelihood of a Monte Carlo simulation of the stellar population of Leo A being a good match to the data within the well understood errors in the data. The magnitude limits on our data are sensitive enough to look back at ~1 Gyr of star formation history at the distance of Leo A. To explain the observed ratio of red to blue stars in the observed CMD, it is necessary to invoke either a steadily decreasing star formation rate toward the present time or gaps in the star formation history. We also compare the properties of the observed stellar population with the known spatial distribution of the H I gas and H II regions to support the conclusions from CMD modeling. We consider the possibility that currently there is a period of diminished star formation in Leo A, as evidenced by the lack of very young stars in the CMD and the faint H II regions. How the chaotic H I distribution, with no observable rotation, fits into our picture of the evolution of Leo A is as yet unclear.

Endochondral gigantism: a newly recognized skeletal dysplasia with pre- and postnatal overgrowth and endocrine abnormalities.

Science.gov (United States)

Schmidt, Heinrich; Kammer, Birgit; Grasser, Monika; Enders, Angelika; Rost, Imma; Kiess, Wieland

2007-08-15

We report on a 3-year-old male, born at 34 weeks of gestation, with marked pre- and postnatal overgrowth, birth weight of 6,600 g, length of 61 cm, and head circumference of 38.5 cm. A striking phenotype was recorded at birth, which became more evident during the follow-up period. He had macrobrachycephaly, facial abnormalities, small thoracic cage, long trunk, deformed spine, rhizomelia, large hands and feets, absent subcutaneous fat, small umbilical hernia, inguinal hernias, and large joints with mild contractures. Hypoglycemic episodes and obstructive apnea complicated the neonatal period. During follow-up, overgrowth continued with a height of 146 cm (+11.65 SDS) and a weight of 39 kg (BMI 18.3 kg/m(2)) at 3.5 years. Endocrinological work-up disclosed extremely low levels of growth hormone, insulin-like growth factors, and insulin. What makes our patient unique is the association of marked prenatal overgrowth; unusual phenotype; skeletal dysplasia caused by accelerated endochondral ossification resulting in cartilage hyperplasia of the skull base and spine, and postnatal gigantism; and complete absence of subcutaneous fat. Other well-known overgrowth syndromes were excluded. We hypothesize that autocrine/paracrine growth factors could be the cause of excessive endochondral ossification. Alternately, activating mutations in transcription factors involved in both growth and endocrine/metabolic homeostasis could be responsible for this unusual phenotype. (c) 2007 Wiley-Liss, Inc.

Surgical management of gingival overgrowth associated with Cowden sydrome: a case report and current understanding.

Science.gov (United States)

Feitosa, Daniela da Silva; Santamaria, Mauro Pedrine; Casati, Márcio Zaffalon; Sallum, Enilson Antonio; Nociti Júnior, Francisco Humberto; de Toledo, Sérgio

2011-05-01

Cowden syndrome, also known as multiple hamartoma syndrome, is a rare autosomal dominant disorder characterized by multiple hamartomas and a high risk of development of malignancy. Oral findings, such as papillomatous lesions and fibromas, are common features; however, a periodontal phenotype has not been reported previously. Therefore, this report presents a case of gingival overgrowth associated with Cowden syndrome, its successful surgical management, and the 12-month follow-up results. Additionally, we discuss the implications for clinicians. A 23-year-old woman was referred to the Department of Periodontics, Piracicaba Dental School, presenting with generalized gingival overgrowth. A detailed dental and medical history and clinical examination confirmed the systemic diagnosis of Cowden syndrome. Histology, radiographs, and clinical data document the entire clinical approach and follow-up. Clinically, there were minor signs of recurrence of gingival overgrowth in a 12-month period after gingivectomy; however, papular lesions reappeared in keratinized gingiva immediately after healing. No signs of bone loss related to the systemic condition were observed radiographically. Histologically, a dense connective tissue with a moderate chronic inflammatory infiltrate and epithelial acanthosis, which is characteristic of gingival hyperplasia, were demonstrated. Gingival overgrowth may occur as an oral phenotype related to Cowden syndrome and can be successfully treated by means of external bevel gingivectomy, followed by regular maintenance therapy, contributing to the patient's well-being, both functionally and esthetically.

Addition of Sb as a surfactant for the growth of nonpolar a-plane GaN by using mixed-source hydride vapor phase epitaxy

International Nuclear Information System (INIS)

Ok, Jin Eun; Jo, Dong Wan; Yun, Wy Il; Han, Young Hun; Jeon, Hun Soo; Lee, Gang Suok; Jung, Se Gyo; Bae, Seon Min; Ahn, Hyung Soo; Yang, Min

2011-01-01

The influence of Sb as a surfactant on the morphology and on the structural and the optical characteristics of a-plane GaN grown on r-plane sapphire by using mixed-source hydride vapor phase epitaxy was investigated. The a-plane GaN:Sb layers were grown at various temperatures ranging from 1000 .deg. C to 1100 .deg. C, and the reactor pressure was maintained at 1 atm. The atomic force microscope (AFM), scanning electron microscope (SEM), X-ray diffraction (XRD) and photoluminescence(PL) results indicated that the surface morphologies and the structural and the optical characteristics of a-plane GaN were markedly improved, compared to the a-plane GaN layers grown without Sb, by using Sb as a surfactant. The addition of Sb was found to alter epitaxial lateral overgrowth (ELO) facet formation. The Sb was not detected from the a-plane-GaN epilayers within the detection limit of the energy dispersive spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS) measurements, suggesting that Sb act as a surfactant during the growth of a-plane GaN by using mixed-source HVPE method.

SacB-SacR gene cassette as the negative selection marker to suppress Agrobacterium overgrowth in Agrobacterium-mediated plant transformation

Science.gov (United States)

Agrobacterium overgrowth is a common problem in Agrobacterium-mediated plant transformation. To suppress the Agrobacterium overgrowth, various antibiotics have been used during plant tissue culture steps. The antibiotics are expensive and may adversely affect plant cell differentiation and reduce ...

Viiv enne kojuminekut / Leo Kunnas ; interv. Helen Arak

Index Scriptorium Estoniae

Kunnas, Leo, 1967-

2006-01-01

Kaitsejõudude Peastaabi operatiivosakonna ülem kolonelleitnant Leo Kunnas oma perekonnast, lapsepõlvekodust Põlvamaal ja praegusest elamisest Tallinnas, missioonil viibivate sõjaväelaste probleemidest ning eluolust Iraagis. Lisa: Katkend Leo Kunnase raamatust "Viiv pikas sõjas"

Is periodontal health a predictor of drug-induced gingival overgrowth? A cross-sectional study

Directory of Open Access Journals (Sweden)

Ruchi Banthia

2014-01-01

Full Text Available Background: Gingival overgrowth is a common side-effect of amlodipine regimen on the oral cavity. There is controversy regarding the cause and effect relationship of periodontal health and drug induced gingival overgrowth. Therefore, this study was conducted to investigate and to assess the relationship between the periodontal health and the onset and severity of gingival overgrowth in hypertensive patients receiving amlodipine. Materials and Methods: A total of 99 known hypertensive patients on amlodipine regimen were included in this study. Probing pocket depth (PPD and clinical attachment loss (CAL were noted on four sites of maxillary and mandibular anterior teeth. Gingival enlargement scores were assessed for each patient by employing the hyperplastic index. Oral hygiene status was evaluated using the calculus index (CI. Patients were divided into H, E and L groups based on their periodontal status and responders and non-responders based on their hyperplastic index scores. Differences in means of different periodontal variables in different groups were tested for significance by using ANOVA and unpaired Student t-test. Pearson′s correlation coefficient was calculated to assess the correlation between different variables. For all analyses, P < 0.05 was considered to be significant. Results: All the periodontal parameters were statistically highly significant (P = 0.00 amongst H, E and L groups and between responders and non-responders. Statistically highly significant Pearson correlation coefficients were found between mean PPD and mean hyperplastic score, mean CAL and mean hyperplastic score and mean calculus and mean hyperplastic score. Conclusion: The results of this study indicated a definite association between periodontal health and development and severity of amlodipine-induced gingival overgrowth

Desenvolvimento de uma unidade virtual para desasfaltação de resíduos pesados de petróleo para maximização de óleo desasfaltado e daí óleo lubrificante

OpenAIRE

Ayda Karina León Ayala

2011-01-01

Resumo: O aumento mundial na demanda de energia e o descobrimento de óleo pesado e viscoso por parte da PETROBRAS nos últimos anos têm incrementado o desenvolvimento de novas tecnologias no Brasil para o processamento deste tipo de petróleo, assim como a adequação dos processos já existentes nas refinarias, visando atingir os requerimentos do mercado ao se obter produtos leves de alto valor comercial. No caso da produção de óleos lubrificantes tem se aumentado a necessidade de se conhecer o p...

Small intestinal bacterial overgrowth in patients with systemic sclerosis

Directory of Open Access Journals (Sweden)

Saara Rawn

2017-01-01

Full Text Available Small intestinal bacterial overgrowth (SIBO is common in patients with systemic sclerosis (SSc yet often goes underrecognized in clinical practice. In patients with SSc, untreated SIBO may result in marked morbidity and possible mortality. The pathogenesis of SIBO is multifactorial and relates to immune dysregulation, vasculopathy, and dysmotility. This article reviews various diagnostic approaches and therapeutic options for SIBO. Treatment modalities mainly include prokinetics, probiotics, and antibiotics.

Bacteria: a new player in gastrointestinal motility disorders--infections, bacterial overgrowth, and probiotics.

LENUS (Irish Health Repository)

Quigley, Eamonn M M

2012-02-03

Irritable bowel syndrome (IBS) may result from a dysfunctional interaction between the indigenous flora and the intestinal mucosa, which in turn leads to immune activation in the colonic mucosa. Some propose that bacterial overgrowth is a common causative factor in the pathogenesis of symptoms in IBS; others point to evidence suggesting that the cause stems from more subtle qualitative changes in the colonic flora. Bacterial overgrowth will probably prove not to be a major factor in what will eventually be defined as IBS. Nevertheless, short-term therapy with either antibiotics or probiotics seems to reduce symptoms among IBS patients. However, in the long term, safety issues will favor the probiotic approach; results of long-term studies with these agents are eagerly awaited.

Leo Kunnas, sõdurjumala teener / Leo Kunnas ; interv. Eve Jaakson

Index Scriptorium Estoniae

Kunnas, Leo, 1967-

2006-01-01

Kaitsejõudude peastaabi operatiivosakonna ülem kolonelleitnant Leo Kunnas räägib Iraagi sõja kogemustest ja oma raamatust "Viiv pikas sõjas. Märkmeid Iraagi sõjast", riigikaitsest, kaitseväeteenistusest, kaitseminister Jürgen Ligist, kaitsepoliitikast, NATO-st, sõjalisest koostööst, perekonnast. Kommenteerivad Sten Reimann ja Venno Loosaar

Epitaxial growth of hybrid nanostructures

Science.gov (United States)

Tan, Chaoliang; Chen, Junze; Wu, Xue-Jun; Zhang, Hua

2018-02-01

Hybrid nanostructures are a class of materials that are typically composed of two or more different components, in which each component has at least one dimension on the nanoscale. The rational design and controlled synthesis of hybrid nanostructures are of great importance in enabling the fine tuning of their properties and functions. Epitaxial growth is a promising approach to the controlled synthesis of hybrid nanostructures with desired structures, crystal phases, exposed facets and/or interfaces. This Review provides a critical summary of the state of the art in the field of epitaxial growth of hybrid nanostructures. We discuss the historical development, architectures and compositions, epitaxy methods, characterization techniques and advantages of epitaxial hybrid nanostructures. Finally, we provide insight into future research directions in this area, which include the epitaxial growth of hybrid nanostructures from a wider range of materials, the study of the underlying mechanism and determining the role of epitaxial growth in influencing the properties and application performance of hybrid nanostructures.

Chromosome 15q overgrowth syndrome: Prenatal diagnosis, molecular cytogenetic characterization, and perinatal findings in a fetus with dup(15(q26.2q26.3

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Chih-Ping Chen

2011-09-01

Conclusion: The present case provides evidence for prenatal overgrowth, craniosynostosis, and characteristic facial dysmorphism in association with a duplication of 15q26.2→q26.3 and a duplication of the IGF1R gene. Prenatal diagnosis of fetal overgrowth should include a differential diagnosis of the chromosome 15q overgrowth syndrome.

Óleo funcional na dieta de vacas leiteiras

OpenAIRE

Jesus, Elmeson Ferreira de [UNESP

2015-01-01

O presente estudo teve como objetivo avaliar os efeitos da inclusão de óleo funcional composto de ácido anacárdico, cardol e cardanol (óleo da castanha de cajú) e ácido ricinoleico (óleo de mamona) na dieta de vacas em lactação sobre consumo, digestibilidade aparente total da matéria seca e nutrientes, fermentação ruminal, produção e composição do leite, síntese de proteína microbiana, perfil metabólico, balanço de nitrogênio e energia. Foram utilizadas vinte e quatro vacas pluriparas da raça...

Differential Diagnoses of Overgrowth Syndromes: The Most Important Clinical and Radiological Disease Manifestations

International Nuclear Information System (INIS)

Lacerda, L.S.; Alves, U.D.; Zanier, J.F.C.; Machado, D.C.; Camilo, G.B.; Machado, D.C.; Camilo, G.B.; Lopes, A.J.

2014-01-01

Overgrowth syndromes comprise a heterogeneous group of diseases that are characterized by excessive tissue development. Some of these syndromes may be associated with dysfunction in the receptor tyrosine kinase (RTK)/PI3K/AKT pathway, which results in an increased expression of the insulin receptor. In the current review, four overgrowth syndromes were characterized (Proteus syndrome, Klippel-Trenaunay-Weber syndrome, Made lung’s disease, and neurofibromatosis type I) and illustrated using cases from our institution. Because these syndromes have overlapping clinical manifestations and have no established genetic tests for their diagnosis, radiological methods are important contributors to the diagnosis of many of these syndromes. The correlation of genetic discoveries and molecular pathways that may contribute to the phenotypic expression is also of interest, as this may lead to potential therapeutic interventions

Epitaxial growth of CZT(S,Se) on silicon

Science.gov (United States)

Bojarczuk, Nestor A.; Gershon, Talia S.; Guha, Supratik; Shin, Byungha; Zhu, Yu

2016-03-15

Techniques for epitaxial growth of CZT(S,Se) materials on Si are provided. In one aspect, a method of forming an epitaxial kesterite material is provided which includes the steps of: selecting a Si substrate based on a crystallographic orientation of the Si substrate; forming an epitaxial oxide interlayer on the Si substrate to enhance wettability of the epitaxial kesterite material on the Si substrate, wherein the epitaxial oxide interlayer is formed from a material that is lattice-matched to Si; and forming the epitaxial kesterite material on a side of the epitaxial oxide interlayer opposite the Si substrate, wherein the epitaxial kesterite material includes Cu, Zn, Sn, and at least one of S and Se, and wherein a crystallographic orientation of the epitaxial kesterite material is based on the crystallographic orientation of the Si substrate. A method of forming an epitaxial kesterite-based photovoltaic device and an epitaxial kesterite-based device are also provided.

Mutations in the DNA methyltransferase gene DNMT3A cause an overgrowth syndrome with intellectual disability.

Science.gov (United States)

Tatton-Brown, Katrina; Seal, Sheila; Ruark, Elise; Harmer, Jenny; Ramsay, Emma; Del Vecchio Duarte, Silvana; Zachariou, Anna; Hanks, Sandra; O'Brien, Eleanor; Aksglaede, Lise; Baralle, Diana; Dabir, Tabib; Gener, Blanca; Goudie, David; Homfray, Tessa; Kumar, Ajith; Pilz, Daniela T; Selicorni, Angelo; Temple, I Karen; Van Maldergem, Lionel; Yachelevich, Naomi; van Montfort, Robert; Rahman, Nazneen

2014-04-01

Overgrowth disorders are a heterogeneous group of conditions characterized by increased growth parameters and other variable clinical features such as intellectual disability and facial dysmorphism. To identify new causes of human overgrowth, we performed exome sequencing in ten proband-parent trios and detected two de novo DNMT3A mutations. We identified 11 additional de novo mutations by sequencing DNMT3A in a further 142 individuals with overgrowth. The mutations alter residues in functional DNMT3A domains, and protein modeling suggests that they interfere with domain-domain interactions and histone binding. Similar mutations were not present in 1,000 UK population controls (13/152 cases versus 0/1,000 controls; P < 0.0001). Mutation carriers had a distinctive facial appearance, intellectual disability and greater height. DNMT3A encodes a DNA methyltransferase essential for establishing methylation during embryogenesis and is commonly somatically mutated in acute myeloid leukemia. Thus, DNMT3A joins an emerging group of epigenetic DNA- and histone-modifying genes associated with both developmental growth disorders and hematological malignancies.

Mutations in the DNA methyltransferase gene, DNMT3A, cause an overgrowth syndrome with intellectual disability

Science.gov (United States)

Tatton-Brown, Katrina; Seal, Sheila; Ruark, Elise; Harmer, Jenny; Ramsay, Emma; del Vecchio Duarte, Silvana; Zachariou, Anna; Hanks, Sandra; O’Brien, Eleanor; Aksglaede, Lise; Baralle, Diana; Dabir, Tabib; Gener, Blanca; Goudie, David; Homfray, Tessa; Kumar, Ajith; Pilz, Daniela T; Selicorni, Angelo; Temple, I Karen; Van Maldergem, Lionel; Yachelevich, Naomi; van Montfort, Robert; Rahman, Nazneen

2014-01-01

Overgrowth disorders are a heterogeneous group of conditions characterised by increased growth parameters and variable other clinical features, such as intellectual disability and facial dysmorphism1. To identify novel causes of human overgrowth we performed exome sequencing in 10 proband-parent trios and detected two de novo DNMT3A mutations. We identified 11 additional de novo mutations through DNMT3A sequencing of a further 142 individuals with overgrowth. The mutations were all located in functional DNMT3A domains and protein modelling suggests they interfere with domain-domain interactions and histone binding. No similar mutations were present in 1000 UK population controls (13/152 vs 0/1000; P<0.0001). Mutation carriers had a distinctive facial appearance, intellectual disability and increased height. DNMT3A encodes a key methyltransferase essential for establishing the methylation imprint in embryogenesis and is commonly somatically mutated in acute myeloid leukaemia2-4. Thus DNMT3A joins an emerging group of epigenetic DNA and histone modifying genes associated with both developmental growth disorders and haematological malignancies5. PMID:24614070

EDITORIAL: Epitaxial graphene Epitaxial graphene

Science.gov (United States)

de Heer, Walt A.; Berger, Claire

2012-04-01

Graphene is widely regarded as an important new electronic material with interesting two-dimensional electron gas properties. Not only that, but graphene is widely considered to be an important new material for large-scale integrated electronic devices that may eventually even succeed silicon. In fact, there are countless publications that demonstrate the amazing applications potential of graphene. In order to realize graphene electronics, a platform is required that is compatible with large-scale electronics processing methods. It was clear from the outset that graphene grown epitaxially on silicon carbide substrates was exceptionally well suited as a platform for graphene-based electronics, not only because the graphene sheets are grown directly on electronics-grade silicon carbide (an important semiconductor in its own right), but also because these sheets are oriented with respect to the semiconductor. Moreover, the extremely high temperatures involved in production assure essentially defect-free and contamination-free materials with well-defined interfaces. Epitaxial graphene on silicon carbide is not a unique material, but actually a class of materials. It is a complex structure consisting of a reconstructed silicon carbide surface, which, for planar hexagonal silicon carbide, is either the silicon- or the carbon-terminated face, an interfacial carbon rich layer, followed by one or more graphene layers. Consequently, the structure of graphene films on silicon carbide turns out to be a rich surface-science puzzle that has been intensively studied and systematically unravelled with a wide variety of surface science probes. Moreover, the graphene films produced on the carbon-terminated face turn out to be rotationally stacked, resulting in unique and important structural and electronic properties. Finally, in contrast to essentially all other graphene production methods, epitaxial graphene can be grown on structured silicon carbide surfaces to produce graphene

Comparison of the 1-gram [14C]xylose, 10-gram lactulose-H2, and 80-gram glucose-H2 breath tests in patients with small intestine bacterial overgrowth

International Nuclear Information System (INIS)

King, C.E.; Toskes, P.P.

1986-01-01

The sensitivity of three breath tests (1-g [ 14 C]xylose, 10-g lactulose-H 2 , and 80-g glucose-H 2 ) was studied in 20 subjects with culture-documented small intestine bacterial overgrowth. Elevated breath 14 CO2 levels were seen within 30 min of [ 14 C]xylose administration in 19 of 20 subjects with bacterial overgrowth and 0 of 10 controls. In contrast, H 2 breath tests demonstrated uninterpretable tests (absence of H 2 -generating bacteria) in 2 of 20 subjects with bacterial overgrowth and 1 of 10 controls and nondiagnostic increases in H 2 production in 3 of 18 glucose-H 2 and 7 of 18 lactulose-H 2 breath tests in subjects with bacterial overgrowth. These findings demonstrate continued excellent reliability of the 1-g [ 14 C]xylose breath test as a diagnostic test for bacterial overgrowth, indicate inadequate sensitivity of H 2 breath tests in detecting bacterial overgrowth, and suggest the need for evaluation of a 13 CO 2 breath test having the same characteristics as the [ 14 C]xylose test (avidly absorbed substrate having minimal contact with the colonic flora) for nonradioactive breath detection of bacterial overgrowth in children and reproductive-age women

Early Generalized Overgrowth in Boys With Autism

Science.gov (United States)

Chawarska, Katarzyna; Campbell, Daniel; Chen, Lisha; Shic, Frederick; Klin, Ami; Chang, Joseph

2016-01-01

Context Multiple studies have reported an overgrowth in head circumference (HC) in the first year of life in autism. However, it is unclear whether this phenomenon is independent of overall body growth and whether it is associated with specific social or cognitive features. Objectives To examine the trajectory of early HC growth in autism compared with control groups; to assess whether HC growth in autism is independent of height and weight growth during infancy; and to examine HC growth from birth to 24 months in relationship to social, verbal, cognitive, and adaptive functioning levels. Design Retrospective study. Setting A specialized university-based clinic. Participants Boys diagnosed as having autistic disorder (n=64), pervasive developmental disorder–not otherwise specified (n=34), global developmental delay (n=13), and other developmental problems (n=18) and typically developing boys (n=55). Main Outcome Measures Age-related changes in HC, height, and weight between birth and age 24 months; measures of social, verbal, and cognitive functioning at age 2 years. Results Compared with typically developing controls, boys with autism were significantly longer by age 4.8 months, had a larger HC by age 9.5 months, and weighed more by age 11.4 months (P=.05 for all). None of the other clinical groups showed a similar overgrowth pattern. Boys with autism who were in the top 10% of overall physical size in infancy exhibited greater severity of social deficits (P=.009) and lower adaptive functioning (P=.03). Conclusions Boys with autism experienced accelerated HC growth in the first year of life. However, this phenomenon reflected a generalized process affecting other morphologic features, including height and weight. The study highlights the importance of studying factors that influence not only neuronal development but also skeletal growth in autism. PMID:21969460

[Estimation of small intestinal bacterial overgrowth in patients with constipation and diarrhea irritable bowel syndrome].

Science.gov (United States)

Łokieć, Katarzyna; Klupińska, Grazyna; Walecka-Kapica, Ewa; Błońska, Aleksandra

2014-05-01

Irritable bowel syndrome (IBS) is one of the most common reason for gastroenterology consultations. The diverse in symptomatology of the disease comes from its rich etiopathogenesis. Recently studies talk about infectious etiology of IBS and because of that it is necessary to expand its diagnostics by small intestinal bacterial overgrowth (SIBO) test. The aim of this study was to evaluate the prevalence of small intestinal bacterial overgrowth in patients with constipation (IBS-C) and diarrhea (IBS-D) irritable bowel syndrome with regard to nutrition. The study involved 46 subjects (33 women and 13 men) in average age of 44 years, which were divided into two groups: diarrhea and constipation IBS. All patients underwent hydrogen breath test studying bacterial overgrowth in the small intestine. In addition, each person had fulfilled a feeding questionnaire. Student's t-test, Pearson test. It has been shown that there is no statistical significances between the prevalence of SIBO in form of diarrheal IBS and constipation IBS and gender. Average value of increments of hydrogen in breath during the test was higher in IBS-C in comparison with IBS-D, which was the highest in the intestine bacterial overgrowth in patients with IBS-C. STATISTICAL ANALYSIS showed that there is no relationship between the type and frequency of consumption of milk, meat, fruit and vegetables, sweets and coffee and the prevalence of SIBO in form of diarrhea and constipation IBS. The occurrence of constipation or diarrhea irritable bowel syndrome is not related to gender. SIBO is more common in patients with IBS-C than in IBS-D group. There is no relationship between the type of food consumed and the amount of SIBO in people with IBS. Type of food intake do not affect the status of the intestinal flora of people with IBS.

Small intestine bacterial overgrowth and irritable bowel syndrome-related symptoms: Experience with Rifaximin

OpenAIRE

Peralta, Sergio; Cottone, Claudia; Doveri, Tiziana; Almasio, Piero Luigi; Craxi, Antonio

2009-01-01

AIM: To estimate the prevalence of small intestinal bacterial overgrowth (SIBO) in our geographical area (Western Sicily, Italy) by means of an observational study, and to gather information on the use of locally active, non-absorbable antibiotics for treatment of SIBO.

Growth and characterization of AlxGa1-xN LEO substrates

International Nuclear Information System (INIS)

Paek, H.S.; Sakong, T.; Lee, S.N.; Son, J.K.; Ryu, H.Y.; Nam, O.H.; Park, Y.

2006-01-01

We have studied the effect of Al composition on the properties of Al x Ga 1-x N LEO substrates. Al x Ga 1-x N LEO substrates were prepared on stripe-patterned 2μm-thick undoped GaN/sapphire substrates by metalorganic chemical vapor deposition. To investigate the dislocation and crack density, and the surface morphology of Al x Ga 1-x N LEO substrates with different Al compositions, photoluminescence and optical microscope were used. At a 1% of Al composition, we obtained crack-free and mirror-like substrates having a low dislocation density of ∼1E6cm -2 . We expect considerable reduction in threshold current density to be achieved from blue-violet laser diodes grown on Al x Ga 1-x N LEO substrates because of the increased optical gain, as compared to the laser diodes grown on Al-free LEO substrates

A survey on the effects of Azithromycin in the treatment of gingival overgrowth induced by Cyclosporin in renal transplant patients

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Kadkhoda Z.

2004-07-01

Full Text Available Statement of Problem: Gingival overgrowth is a side effect commonly induced by Cyclosporin treatment. The effects of Azithromycin, a macrolidic antibiotic, has been focused on gingival enlargement treatment induced by cyclosporine in numerous articles. Purpose: The goal of the present study was to survey the effects of systemic Azithromycin in the treatment of gingival overgrowth induced by cyclosporine among renal transplant patients. Materials and Methods: In this clinical trial study, 18 renal transplant patients (6 females and 12 males with gingival overgrowth were studied. Samples were randomly divided into two groups: case group were treated by systemic Azithromycin and controls were treated by systemic placebo. Periodontal parameters including bleeding on probing (BOP, clinical crown length (CL, periodontal pocket depth (PPD, gingival overgrowth (GOI and stent-IDP (vertical distant between a stent or plate with teeth occlusal planes at least from three of the most anterior contact points to mesial papillae before treatment, two and six weeks after treatment were measured. To analyze the data, Wilcoxon and Mann-Whitney tests were used. Results: Most of the measured indices, among case and control groups, were significantly improved, after two weeks (P<0.05. No statistically significant differences were found between two groups except for BOP index (P<0.05. In other words, more BOP improvement was observed in the case group after six weeks comparing to the control group. Conclusion: Considering the findings of this study, one can assume that the reported effects of Azithromycine on gingival overgrowth, induced by cyclosporine is somehow exaggerated and the effects attributed this medicine is probably inflammation reduction.

SacB-SacR gene cassette as the negative selection marker to suppress Agrobacterium overgrowth in Agrobacterium-mediated plant transformation

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Yiming Liu

2016-10-01

Full Text Available Agrobacterium overgrowth is a common problem in Agrobacterium-mediated plant transfor-mation. To suppress the Agrobacterium overgrowth, various antibiotics have been used during plant tissue culture steps. The antibiotics are expensive and may adversely affect plant cell differentiation and reduce plant transformation efficiency. The SacB-SacR proteins are toxic to most Agrobacterium tumefaciens strains when they are grown on culture medium sup¬plemented with sucrose. Therefore, SacB-SacR genes can be used as negative selection markers to suppress the overgrowth of Agrobacterium tumefaciens in the plant tissue culture process. We generated a mutant Agrobacterium tumefaciens strain GV2260 (recA-SacB/R that has the SacB-SacR cassette inserted into the bacterial genome at the recA gene locus. The mutant Agrobacterium strain is sensitive to sucrose but maintains its ability to transform plant cells in both transient and stable transformation assays. We demonstrated that the mutant strain GV2260 (recA-SacB/R can be inhibited by sucrose that reduces the overgrowth of Agrobacterium and therefore improves the plant transformation efficiency. We employed GV2260 (recA-SacB/R to generate stable transgenic N. benthamiana plants expressing a CRISPR-Cas9 for knocking out a WRKY transcrip¬tion factor.

Desempenho de um trator agrícola de pneus, funcionando com misturas de óleo diesel e óleo de soja reutilizado

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Wagner da Cunha Siqueira

2011-10-01

Full Text Available No Brasil, a forma de energia alternativa mais atraente tem sido a biomassa e, mais recentemente, os óleos vegetais residuais e in natura. Portanto, objetivou-se, com este trabalho, avaliar o desempenho na tomada de potência de um trator agrícola de pneus, utilizando misturas de óleo Diesel (OD com óleo de soja reutilizádo (OSR. Primeiramente, foi realizado um estudo de densidade das misturas, comportamento da temperatura do óleo Diesel no sistema de alimentação de combustível do motor e análises de viscosidades das misturas em estudo. Após as análises, verificou-se, por meio de ensaios dinamométricos, o desempenho do motor alimentado com misturas de OD com OSR, em diferentes proporções. As principais conclusões deste trabalho foram: a para as avaliações na tomada de potência, a mistura de 25% OD com 75% OSR apresentou a maior potência entre as demais misturas; b o consumo especifico e os torques demonstraram tendência a maiores valores com o acréscimo da percentagem de OSR às misturas.

The Oxygen and Nitrogen Abundance of Leo A and GR 8

Science.gov (United States)

van Zee, L.; Skillman, E. D.; Haynes, M. P.

1999-05-01

Gas phase abundances are one of the best measures of the intrinsic metallicity of low mass galaxies. We recently obtained low resolution long slit optical spectra of several HII regions in Leo A and GR 8 with the Palomar 5m telescope. Previous studies of the resolved stellar population of Leo A indicated that the stars have metallicities approximately 2% of solar (Tolstoy et al. 1998). Preliminary analysis of the HII region spectra, and that of a planetary nebula, indicates that the gas phase oxygen abundance of Leo A is approximately 3% of solar. This confirms the result of Skillman et al. (1989), who also derived an oxygen abundance for Leo A from a planetary nebula. Similarly, for GR 8 we find a mean oxygen abundance of 5% of solar. For all the HII regions, the derived log(N/O) is -1.5 +/- 0.1, as has been found for other low metallicity systems. These new observations of multiple HII regions in Leo A and GR 8 confirm that metals in low mass galaxies are well mixed.

A DEEPER LOOK AT LEO IV: STAR FORMATION HISTORY AND EXTENDED STRUCTURE

International Nuclear Information System (INIS)

Sand, David J.; Seth, Anil; Olszewski, Edward W.; Zaritsky, Dennis; Willman, Beth; Kallivayalil, Nitya

2010-01-01

We present MMT/Megacam imaging of the Leo IV dwarf galaxy in order to investigate its structure and star formation history, and to search for signs of association with the recently discovered Leo V satellite. Based on parameterized fits, we find that Leo IV is round, with ε h ≅ 130 pc. Additionally, we perform a thorough search for extended structures in the plane of the sky and along the line of sight. We derive our surface brightness detection limit by implanting fake structures into our catalog with stellar populations identical to that of Leo IV. We show that we are sensitive to stream-like structures with surface brightness μ r ∼ -2 , and at this limit we find no stellar bridge between Leo IV (out to a radius of ∼0.5 kpc) and the recently discovered, nearby satellite Leo V. Using the color-magnitude fitting package StarFISH, we determine that Leo IV is consistent with a single age (∼14 Gyr), single metallicity ([Fe/H] ∼ -2.3) stellar population, although we cannot rule out a significant spread in these values. We derive a luminosity of M V = -5.5 ± 0.3. Studying both the spatial distribution and frequency of Leo IV's 'blue plume' stars reveals evidence for a young (∼2 Gyr) stellar population which makes up ∼2% of its stellar mass. This sprinkling of star formation, only detectable in this deep study, highlights the need for further imaging of the new Milky Way satellites along with theoretical work on the expected, detailed properties of these possible 'reionization fossils'.

Maternal Inflammation Contributes to Brain Overgrowth and Autism-Associated Behaviors through Altered Redox Signaling in Stem and Progenitor Cells

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Janel E. Le Belle

2014-11-01

Full Text Available A period of mild brain overgrowth with an unknown etiology has been identified as one of the most common phenotypes in autism. Here, we test the hypothesis that maternal inflammation during critical periods of embryonic development can cause brain overgrowth and autism-associated behaviors as a result of altered neural stem cell function. Pregnant mice treated with low-dose lipopolysaccharide at embryonic day 9 had offspring with brain overgrowth, with a more pronounced effect in PTEN heterozygotes. Exposure to maternal inflammation also enhanced NADPH oxidase (NOX-PI3K pathway signaling, stimulated the hyperproliferation of neural stem and progenitor cells, increased forebrain microglia, and produced abnormal autism-associated behaviors in affected pups. Our evidence supports the idea that a prenatal neuroinflammatory dysregulation in neural stem cell redox signaling can act in concert with underlying genetic susceptibilities to affect cellular responses to environmentally altered cellular levels of reactive oxygen species.

THE ARECIBO LEGACY FAST ALFA SURVEY. IX. THE LEO REGION H I CATALOG, GROUP MEMBERSHIP, AND THE H I MASS FUNCTION FOR THE LEO I GROUP

International Nuclear Information System (INIS)

Stierwalt, Sabrina; Haynes, Martha P.; Giovanelli, Riccardo; Martin, Ann M.; Kent, Brian R.; Saintonge, Amelie; Karachentsev, Igor D.; Karachentseva, Valentina E.

2009-01-01

We present the catalog of H I sources extracted from the ongoing Arecibo Legacy Fast ALFA (ALFALFA) extragalactic H I line survey, found within the sky region bounded by 9 h 36 m h 36 m and +08 0 0 . The H I catalog presented here for this 118 deg 2 region is combined with the ones derived from surrounding regions also covered by the ALFALFA survey to examine the large-scale structure in the complex Leo region. Because of the combination of wide sky coverage and superior sensitivity, spatial and spectral resolution, the ALFALFA H I catalog of the Leo region improves significantly on the numbers of low H I mass sources as compared with those found in previous H I surveys. The H I mass function of the Leo I group presented here is dominated by low-mass objects: 45 of the 65 Leo I members have M H I 8 M-odot, yielding tight constraints on the low-mass slope of the Leo I H I mass function. The best-fit slope is α ≅ -1.41 + 0.2 - 0.1. A direct comparison between the ALFALFA H I line detections and an optical search of the Leo I region proves the advantage of the ALFALFA strategy in finding low-mass, gas-rich dwarfs. These results suggest the existence of a significant population of low surface brightness, gas-rich, yet still very low H I mass galaxies, and may reflect the same type of morphological segregation as is seen in the Local Group. While the low-mass end slope of the Leo I H I mass function is steeper than that determined for luminosity functions of the group, the slope still falls short of the values predicted by simulations of structure formation in the lambda cold dark matter paradigm.

Epitaxial graphene electronic structure and transport

International Nuclear Information System (INIS)

De Heer, Walt A; Berger, Claire; Wu Xiaosong; Sprinkle, Mike; Hu Yike; Ruan Ming; First, Phillip N; Stroscio, Joseph A; Haddon, Robert; Piot, Benjamin; Faugeras, Clement; Potemski, Marek; Moon, Jeong-Sun

2010-01-01

Since its inception in 2001, the science and technology of epitaxial graphene on hexagonal silicon carbide has matured into a major international effort and is poised to become the first carbon electronics platform. A historical perspective is presented and the unique electronic properties of single and multilayered epitaxial graphenes on electronics grade silicon carbide are reviewed. Early results on transport and the field effect in Si-face grown graphene monolayers provided proof-of-principle demonstrations. Besides monolayer epitaxial graphene, attention is given to C-face grown multilayer graphene, which consists of electronically decoupled graphene sheets. Production, structure and electronic structure are reviewed. The electronic properties, interrogated using a wide variety of surface, electrical and optical probes, are discussed. An overview is given of recent developments of several device prototypes including resistance standards based on epitaxial graphene quantum Hall devices and new ultrahigh frequency analogue epitaxial graphene amplifiers.

El petróleo como repelente de Phlebotomus

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Marshall Hertig

1943-09-01

Full Text Available Se ha probado el repelente del petróleo contra el Phlebotomus verrucarum. Se echó varias veces petróleo en las paredes exteriores y en el suelo alrededor de casas en la zona verrucógena del Rímac, donde son abundantes las titiras. Inmediatamente después de cada petrolización se redujeron a números insignificantes las titiras dentro de las casas, efecto que duró aproximadamente una semana.

Morfometria testicular de cabritos alimentados com óleo de licuri (Syagrus coronata

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L.P. Barbosa

2012-08-01

Full Text Available Determinou-se o desenvolvimento testicular de caprinos pré-púberes alimentados com óleo de licuri (Syagrus coronata na dieta. Foram utilizados 19 cabritos ¾ Boer, recém-desmamados, com média de idade de três meses. Os animais, submetidos a um período de 75 dias de confinamento, receberam alimentação composta por: farelo de milho, farelo de soja, feno picado de tifton 85 e de óleo de licuri com base na matéria seca. Os animais foram distribuídos em quatro grupos: sem lipídio adicional (n= 5; com 1,5% de óleo de licuri (n= 5; com 3,0% de óleo de licuri (n= 5; e com 4,5% de óleo de licuri (n= 4. As avaliações de peso corporal e de biometria testicular foram realizadas quinzenalmente. Após o período de confinamento, os animais foram abatidos para determinação do peso dos testículos, peso dos epidídimos e índice gonadossomático. A adição de óleo de licuri em até 4,5% na dieta de caprinos pré-púberes não alterou o desenvolvimento testicular com base nas características da biometria e morfometria testicular, indicando que a inclusão de até 4,5% de óleo de licuri na dieta pode ser utilizada.

Epitaxial silicon semiconductor detectors, past developments, future prospects

International Nuclear Information System (INIS)

Gruhn, C.R.

1976-01-01

A review of the main physical characteristics of epitaxial silicon as it relates to detector development is presented. As examples of applications results are presented on (1) epitaxial silicon avalanche diodes (ESAD); signal-to-noise, non-linear aspects of the avalanche gain mechanism, gain-bandwidth product, (2) ultrathin epitaxial silicon surface barrier (ESSB) detectors, response to heavy ions, (3) an all-epitaxial silicon diode (ESD), response to heavy ions, charge transport and charge defect. Future prospects of epitaxial silicon as it relates to new detector designs are summarized

PCVs Estimation and their Impacts on Precise Orbit Determination of LEOs

Science.gov (United States)

Chunmei, Z.; WANG, X.

2017-12-01

In the last decade the precise orbit determination (POD) based on GNSS, such as GPS, has been considered as one of the efficient methods to derive orbits of Low Earth Orbiters (LEOs) that demand accuracy requirements. The Earth gravity field recovery and its related researches require precise dynamic orbits of LEOs. With the improvements of GNSS satellites' orbit and clock accuracy, the algorithm optimization and the refinement of perturbation force models, the antenna phase-center variations (PCVs) of space-borne GNSS receiver have become an increasingly important factor that affects POD accuracy. A series of LEOs such as HY-2, ZY-3 and FY-3 with homebred space-borne GNSS receivers have been launched in the past several years in China. Some of these LEOs load dual-mode GNSS receivers of GPS and BDS signals. The reliable performance of these space-borne receivers has been establishing an important foundation for the future launches of China gravity satellites. Therefore, we first evaluate the data quality of on-board GNSS measurement by examining integrity, multipath error, cycle slip ratio and other quality indices. Then we determine the orbits of several LEOs at different altitudes by the reduced dynamic orbit determination method. The corresponding ionosphere-free carrier phase post-fit residual time series are obtained. And then we establish the PCVs model by the ionosphere-free residual approach and analyze the effects of antenna phase-center variation on orbits. It is shown that orbit accuracy of LEO satellites is greatly improved after in-flight PCV calibration. Finally, focus on the dual-mode receiver of FY-3 satellite we analyze the quality of onboard BDS data and then evaluate the accuracy of the FY-3 orbit determined using only BDS measurement onboard. The accuracy of LEO satellites orbit based on BDS would be well improved with the global completion of BDS by 2020.

Thin epitaxial silicon detectors

International Nuclear Information System (INIS)

Stab, L.

1989-01-01

Manufacturing procedures of thin epitaxial surface barriers will be given. Some improvements have been obtained: larger areas, lower leakage currents and better resolutions. New planar epitaxial dE/dX detectors, made in a collaboration work with ENERTEC-INTERTECHNIQUE, and a new application of these thin planar diodes to EXAFS measurements, made in a collaboration work with LURE (CNRS,CEA,MEN) will also be reported

Methane production and small intestinal bacterial overgrowth in children living in a slum.

Science.gov (United States)

Mello, Carolina Santos; Tahan, Soraia; Melli, Lígia Cristina F L; Rodrigues, Mirian Silva do Carmo; de Mello, Ricardo Martin Pereira; Scaletsky, Isabel Cristina Affonso; de Morais, Mauro Batista

2012-11-07

To analyze small intestinal bacterial overgrowth in school-aged children and the relationship between hydrogen and methane production in breath tests. This transversal study included 85 children residing in a slum and 43 children from a private school, all aged between 6 and 10 years, in Osasco, Brazil. For characterization of the groups, data regarding the socioeconomic status and basic housing sanitary conditions were collected. Anthropometric data was obtained in children from both groups. All children completed the hydrogen (H(2)) and methane (CH(4)) breath test in order to assess small intestinal bacterial overgrowth (SIBO). SIBO was diagnosed when there was an increase in H(2) ≥ 20 ppm or CH(4) ≥ 10 ppm with regard to the fasting value until 60 min after lactulose ingestion. Children from the slum group had worse living conditions and lower nutritional indices than children from the private school. SIBO was found in 30.9% (26/84) of the children from the slum group and in 2.4% (1/41) from the private school group (P = 0.0007). Greater hydrogen production in the small intestine was observed in children from the slum group when compared to children from the private school (P = 0.007). A higher concentration of hydrogen in the small intestine (P slum group with SIBO when compared to children from the slum group without SIBO. Methane production was observed in 63.1% (53/84) of the children from the slum group and in 19.5% (8/41) of the children from the private school group (P slum. Colonic production of hydrogen was lower in methane-producing children (P = 0.017). Children who live in inadequate environmental conditions are at risk of bacterial overgrowth and methane production. Hydrogen is a substrate for methane production in the colon.

BAVP: Blockchain-Based Access Verification Protocol in LEO Constellation Using IBE Keys

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Songjie Wei

2018-01-01

Full Text Available LEO constellation has received intensive research attention in the field of satellite communication. The existing centralized authentication protocols traditionally used for MEO/GEO satellite networks cannot accommodate LEO satellites with frequent user connection switching. This paper proposes a fast and efficient access verification protocol named BAVP by combining identity-based encryption and blockchain technology. Two different key management schemes with IBE and blockchain, respectively, are investigated, which further enhance the authentication reliability and efficiency in LEO constellation. Experiments on OPNET simulation platform evaluate and demonstrate the effectiveness, reliability, and fast-switching efficiency of the proposed protocol. For LEO networks, BAVP surpasses the well-known existing solutions with significant advantages in both performance and scalability which are supported by theoretical analysis and simulation results.

Localized Pd Overgrowth on Cubic Pt Nanocrystals for Enhanced Electrocatalytic Oxidation of Formic Acid

Energy Technology Data Exchange (ETDEWEB)

Lee, H.; Habas, S.E.; Somorjai, G.A.; Yang, P.

2008-03-20

Binary Pt/Pd nanoparticles were synthesized by localized overgrowth of Pd on cubic Pt seeds for the investigation of electrocatalytic formic acid oxidation. The binary particles exhibited much less self-poisoning and a lower activation energy relative to Pt nanocubes, consistent with the single crystal study.

Passivation Strategies on Board Airbus ds Leo Pcdus

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Lapeña Emilio

2017-01-01

This paper deals with the different strategies followed in the Airbus DS LEO PCDUs regarding the implementation of the passivation function in several LEO missions with different architectures (DET and MPPT solar array power conditioning. In the selection of the solution implemented in the frame of every mission, a key driver is the degree of advance in the test performed over flight representative battery modules regarding their safe behavior when deeply depleted after a long period in orbit with the passivation applied over the spacecraft.

Epitaxial rare-earth superlattices and films

International Nuclear Information System (INIS)

Salamon, M.B.; Beach, R.S.; Flynn, C.P.; Matheny, A.; Tsui, F.; Rhyne, J.J.

1992-01-01

This paper reports on epitaxial growth of rare-earth superlattices which is demonstrated to have opened important new areas of research on magnetic materials. The propagation magnetic order through non-magnetic elements, including its range and anisotropy, has been studied. The importance of magnetostriction in determining the phase diagram is demonstrated by the changes induced by epitaxial clamping. The cyrstallinity of epitaxial superlattices provides the opportunity to study interfacial magnetism by conventional x-ray and neutron scattering methods

Refinação de óleos vegetais e fracionamento contínuo de óleo de Palma

OpenAIRE

Mota, Daniel Santos

2016-01-01

Este relatório enquadra-se na unidade de formação de estágio profissionalizante, do Mestrado em Engenharia Alimentar da Escola Superior Agrária de Coimbra e traduz algumas partes do trabalho realizado ao longo de 6 meses de estágio, na empresa Rogério Leal. O estágio consistiu na observação, e posterior participação, dos métodos de refinação, hidrogenação, interestereficação e fracionamento do óleo de palma. Neste relatório descreve-se o método de refinação físico e hidrogenação do óleo...

Leo Kunnas : triibuline särk kuuli ei peata / Leo Kunnas ; interv. Jaanus Piirsalu

Index Scriptorium Estoniae

Kunnas, Leo, 1967-

2006-01-01

2005. aastal koalitsioonijõudude koosseisus Iraagis teeninud Leo Kunnas selgitab intervjuus, mida on Eesti kaitsevägi Iraagi missioonist õppinud, millist mõju on Eesti sõdurite osalemine välismissioonides avaldanud ühiskonnale, lisaks võrdleb Iraagi ja Afganistani missioone ning põhjendab, miks on palgaarmee loomise idee Eestis sõjaliselt mitterelevantne

Geocenter variations derived from a combined processing of LEO- and ground-based GPS observations

Science.gov (United States)

Männel, Benjamin; Rothacher, Markus

2017-08-01

GNSS observations provided by the global tracking network of the International GNSS Service (IGS, Dow et al. in J Geod 83(3):191-198, 2009) play an important role in the realization of a unique terrestrial reference frame that is accurate enough to allow a detailed monitoring of the Earth's system. Combining these ground-based data with GPS observations tracked by high-quality dual-frequency receivers on-board low earth orbiters (LEOs) is a promising way to further improve the realization of the terrestrial reference frame and the estimation of geocenter coordinates, GPS satellite orbits and Earth rotation parameters. To assess the scope of the improvement on the geocenter coordinates, we processed a network of 53 globally distributed and stable IGS stations together with four LEOs (GRACE-A, GRACE-B, OSTM/Jason-2 and GOCE) over a time interval of 3 years (2010-2012). To ensure fully consistent solutions, the zero-difference phase observations of the ground stations and LEOs were processed in a common least-squares adjustment, estimating all the relevant parameters such as GPS and LEO orbits, station coordinates, Earth rotation parameters and geocenter motion. We present the significant impact of the individual LEO and a combination of all four LEOs on the geocenter coordinates. The formal errors are reduced by around 20% due to the inclusion of one LEO into the ground-only solution, while in a solution with four LEOs LEO-specific characteristics are significantly reduced. We compare the derived geocenter coordinates w.r.t. LAGEOS results and external solutions based on GPS and SLR data. We found good agreement in the amplitudes of all components; however, the phases in x- and z-direction do not agree well.

Analysis of the Accuracy of Beidou Combined Orbit Determination Enhanced by LEO and ISL

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FENG Laiping

2017-05-01

Full Text Available In order to improve the precision of BeiDou orbit determination under the conditions of regional ground monitoring station and make good use of increasingly rich on-board data and upcoming ISL technology, a method of BeiDou precision orbit determination is proposed which combines the use of ground monitoring stations data, low earth orbit satellite(LEOs data and Inter-Satellite Link(ISL data. The effects of assisting data of LEOs and ISL on the precision orbit determination of navigation satellite are discussed. Simulation analysis is carried out mainly from the number of LEOs, orbit slot configuration and ISL. The results show that the orbit precision of BeiDou will greatly improve about 73% with a small number of LEOs, while improvement of clock bias is not remarkable; the uniform orbit slot configuration of the same number of LEOs has a modest effect on the accuracy of combined orbit determination; compared with LEOs, the increase of ISL will significantly improve the accuracy of orbit determination with a higher efficiency.

Magnetic state controllable critical temperature in epitaxial Ho/Nb bilayers

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Yuanzhou Gu

2014-04-01

Full Text Available We study the magnetic properties of Ho thin films with different crystallinity (either epitaxial or non-epitaxial and investigate their proximity effects with Nb thin films. Magnetic measurements show that epitaxial Ho has large anisotropy in two different crystal directions in contrast to non-epitaxial Ho. Transport measurements show that the superconducting transition temperature (Tc of Nb thin films can be significantly suppressed at zero field by epitaxial Ho compared with non-epitaxial Ho. We also demonstrate a direct control over Tc by changing the magnetic states of the epitaxial Ho layer, and attribute the strong proximity effects to exchange interaction.

Epitaxial growth of rhenium with sputtering

Energy Technology Data Exchange (ETDEWEB)

Oh, Seongshik [National Institute of Standards and Technology, Boulder, CO 80305 (United States) and Department of Physics, University of Illinois, Urbana, IL 61801 (United States)]. E-mail: soh@boulder.nist.gov; Hite, Dustin A. [National Institute of Standards and Technology, Boulder, CO 80305 (United States); Cicak, K. [National Institute of Standards and Technology, Boulder, CO 80305 (United States); Osborn, Kevin D. [National Institute of Standards and Technology, Boulder, CO 80305 (United States); Simmonds, Raymond W. [National Institute of Standards and Technology, Boulder, CO 80305 (United States); McDermott, Robert [University of California, Santa Barbara, CA 93106 (United States); Cooper, Ken B. [University of California, Santa Barbara, CA 93106 (United States); Steffen, Matthias [University of California, Santa Barbara, CA 93106 (United States); Martinis, John M. [University of California, Santa Barbara, CA 93106 (United States); Pappas, David P. [National Institute of Standards and Technology, Boulder, CO 80305 (United States)

2006-02-21

We have grown epitaxial Rhenium (Re) (0001) films on {alpha}-Al{sub 2}O{sub 3} (0001) substrates using sputter deposition in an ultra high vacuum system. We find that better epitaxy is achieved with DC rather than with RF sputtering. With DC sputtering, epitaxy is obtained with the substrate temperatures above 700 deg. C and deposition rates below 0.1 nm/s. The epitaxial Re films are typically composed of terraced hexagonal islands with screw dislocations, and island size gets larger with high temperature post-deposition annealing. The growth starts in a three dimensional mode but transforms into two dimensional mode as the film gets thicker. With a thin ({approx}2 nm) seed layer deposited at room temperature and annealed at a high temperature, the initial three dimensional growth can be suppressed. This results in larger islands when a thick film is grown at 850 deg. C on the seed layer. We also find that when a room temperature deposited Re film is annealed to higher temperatures, epitaxial features start to show up above {approx}600 deg. C, but the film tends to be disordered.

Óleos essenciais e vegetais no controle in vitro de Colletotrichum gloeosporioides

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K. RAMOS

Full Text Available RESUMO O objetivo deste trabalho foi avaliar a atividade antifúngica de óleos essenciais e vegetais no controle in vitro de Colletotrichum gloeosporioides, agente causal da antracnose em pós-colheita de frutíferas. Treze óleos essenciais foram utilizados em concentrações de 0,00%, 0,40%, 0,80%, 1,70%, 3,20%, 6,25%, 12,50%, 25,00%, 50,00% e 100,00%, e uma linhagem padrão de Colletotrichum gloeosporioides. Foram avaliadas a concentração inibitória mínima e a concentração mínima fungicida a fim de caracterizar o potencial de cada um dos óleos essenciais avaliados. Verificou-se que os óleos utilizados apresentaram atividade fungicida em diferentes concentrações, as quais variaram de 0,80% (melaleuca, 3,20%, (eucalipto, 6,25% (limão, capim limão, cravo da índia, canela e nim, 12,5% (hortelã e citronela, 25% (copaíba, 50% (coco e gengibre e 100% (manjericão. O óleo de nim apresentou maior redução da carga microbiana em função do tempo de exposição, sendo necessários 30 minutos para anulação da contagem microbiana. O efeito antifúngico dos óleos essenciais, para controle de Colletotrichum gloeosporioides, depende da planta e da concentração empregada.

Leo Tolstoy the Spiritual Educator

Science.gov (United States)

Moulin, Dan

2008-01-01

This paper considers the often overlooked religious and educational works of the Russian novelist Leo Tolstoy (1828-1910). After outlining Tolstoy's life, religious and educational views, it is argued that Tolstoy has much to offer spiritual educators today. In particular, it suggests Tolstoy's insistence on the absolute and eternal nature of…

Position-controlled epitaxial III-V nanowires on silicon

NARCIS (Netherlands)

Roest, A.L.; Verheijen, M.A.; Wunnicke, O.; Serafin, S.N.; Wondergem, H.J.; Bakkers, E.P.A.M.

2006-01-01

We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the VLS mechanism with laser ablation as well as metal-organic vapour phase epitaxy. The hetero-epitaxial growth of the III-V nanowires on silicon was confirmed with x-ray diffraction

Telelegend Leo Karpin : ETV uus juhtkond teeb vaid lammutustööd / Leo Karpin ; interv. Verni Leivak

Index Scriptorium Estoniae

Karpin, Leo, 1946-2014

2004-01-01

Pea 40 aastat Eesti Televisioonis töötanud telerežissöör oma teletöölt lahkumise põhjustest. Lisaks kommentaar "ETV juhatuse esimees Ilmar Raag, miks tunnustatud telemees Leo Karpin ametist vabastati?"

Epitaxial growth of silicon for layer transfer

Science.gov (United States)

Teplin, Charles; Branz, Howard M

2015-03-24

Methods of preparing a thin crystalline silicon film for transfer and devices utilizing a transferred crystalline silicon film are disclosed. The methods include preparing a silicon growth substrate which has an interface defining substance associated with an exterior surface. The methods further include depositing an epitaxial layer of silicon on the silicon growth substrate at the surface and separating the epitaxial layer from the substrate substantially along the plane or other surface defined by the interface defining substance. The epitaxial layer may be utilized as a thin film of crystalline silicon in any type of semiconductor device which requires a crystalline silicon layer. In use, the epitaxial transfer layer may be associated with a secondary substrate.

Surgical trauma induces overgrowth in lower limb gigantism: regulation with use of rapamycin is promising.

Science.gov (United States)

Pinto, Rohan Sebastian; Harrison, William David; Graham, Kenneth; Nayagam, Durai

2018-01-04

We describe an unclassified overgrowth syndrome characterised by unregulated growth of dermal fibroblasts in the lower limbs of a 35-year-old woman. A PIK3CA gene mutation resulted in lower limb gigantism. Below the waist, she weighed 117 kg with each leg measuring over 100 cm in circumference. Her total adiposity was 50% accounted for by her legs mainly. Liposuction and surgical debulking were performed to reduce the size of the limbs but had exacerbated the overgrowth in her lower limbs. Systemic sepsis from an infected foot ulcer necessitated treatment by an above-knee amputation. Postoperatively, the stump increased in size by 19 kg. A trial of rapamycin to reverse the growth of the stump has shown promise. We discuss the clinical and genetic features of this previously unclassified disorder and the orthopaedic considerations involved. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

COMPONENTES MINORITÁRIOS DO ÓLEO DE MAMONA (Ricinus comunnis L.

Directory of Open Access Journals (Sweden)

Elina Bastos Caramão

2007-12-01

Full Text Available O óleo extraído de sementes de Ricinnus communis L., conhecida como mamona, foi analisado neste trabalho quanto a presença decomponentes minoritários extraídos na fase insaponificável. A extração de insaponificáveis foi realizada conforme o método AOCS(Ca 6a-40 e a análise das amostras de óleo foi realizada por Cromatografia gasosa acoplada a espectrometria de massas (CG-DEMapós derivatização com BSA. Entre as substâncias identificadas encontrou-se o D-tocoferol, g- tocoferol, D5-ergostenol, stigmasterol,obtusifoliol, g-sitosterol, fucosterol e cicloartenol. As amostras de óleo de diferentes variedades de mamona, obtidas por prensagem afrio e por solvente em extrator soxhlet apresentaram diferenças quanto as substâncias separadas. O método empregado para extração eanálise foi apropriado para identificar a presença de componentes minoritários no óleo de mamona.

EFEITO DE ÓLEOS ESSENCIAIS CÍTRICOS SOBRE Agrotis ipsilon (HUFNAGEL (LEPIDOPTERA:NOCTUIDAE

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Ingrid Schimidt Kaiser

2017-01-01

Full Text Available A utilização de plantas inseticidas é cada vez mais frequente no controle de pragas. As plantas podem produzir diferentes compostos com atividade inseticida. Os óleos essenciais destacam-se dentre estes compostos, possuindo diferentes modos de ação inseticida, podendo ser uma ferramenta útil no manejo integrado de pragas. O objetivo deste trabalho é avaliar o efeito de óleos essenciais cítricos e seu composto majoritário D-limonemo visando sua adoção como métodos alternativos de controle de Agrotis ipsilon (Hufnagel (Lepidoptera: Noctuidae. Para a realização do experimento foram utilizadas 50 lagartas de 1º ínstar por tratamento. Foram aplicados os óleos essenciais com auxilio do aerógrafo, sendo utilizado na concentração de 10% v v-1 para os óleos cítricos e o D-limoneno e para testemunha foi pulverizado água destilada. A avaliação foi realizada após 24, 48 e 72 horas verificando o número de lagartas mortas. Não foi observado efeito tóxico dos óleos essenciais cítricos e do D-limoneno sobre as lagartas de A. ipsilon. Deste modo, os óleos essenciais testados não são eficazes no controle da praga.

One-step Ge/Si epitaxial growth.

Science.gov (United States)

Wu, Hung-Chi; Lin, Bi-Hsuan; Chen, Huang-Chin; Chen, Po-Chin; Sheu, Hwo-Shuenn; Lin, I-Nan; Chiu, Hsin-Tien; Lee, Chi-Young

2011-07-01

Fabricating a low-cost virtual germanium (Ge) template by epitaxial growth of Ge films on silicon wafer with a Ge(x)Si(1-x) (0 deposition method in one step by decomposing a hazardousless GeO(2) powder under hydrogen atmosphere without ultra-high vacuum condition and then depositing in a low-temperature region. X-ray diffraction analysis shows that the Ge film with an epitaxial relationship is along the in-plane direction of Si. The successful growth of epitaxial Ge films on Si substrate demonstrates the feasibility of integrating various functional devices on the Ge/Si substrates.

Study of LEO-SAT microwave link for broad-band mobile satellite communication system

Science.gov (United States)

Fujise, Masayuki; Chujo, Wataru; Chiba, Isamu; Furuhama, Yoji; Kawabata, Kazuaki; Konishi, Yoshihiko

1993-01-01

In the field of mobile satellite communications, a system based on low-earth-orbit satellites (LEO-SAT's) such as the Iridium system has been proposed. The LEO-SAT system is able to offer mobile telecommunication services in high-latitude areas. Rain degradation, fading and shadowing are also expected to be decreased when the system is operated at a high elevation angle. Furthermore, the propagation delay generated in the LEO-SAT system is less pronounced than that in the geostationary orbit satellite (GEO-SAT) system and, in voice services, the effect of the delay is almost negligible. We proposed a concept of a broad-band mobile satellite communication system with LEO-SAT's and Optical ISL. In that system, a fixed L-band (1.6/1.5 GHz) multibeam is used to offer narrow band service to the mobile terminals in the entire area covered by a LEO-SAT and steerable Ka-band (30/20 GHz) spot beams are used for the wide band service. In this paper, we present results of a study of LEO-SAT microwave link between a satellite and a mobile terminal for a broad-band mobile satellite communication system. First, the results of link budget calculations are presented and the antennas mounted on satellites are shown. For a future mobile antenna technology, we also show digital beamforming (DBF) techniques. DBF, together with modulation and/or demodulation, is becoming a key technique for mobile antennas with advanced functions such as antenna pattern calibration, correction, and radio interference suppression. In this paper, efficient DBF techniques for transmitting and receiving are presented. Furthermore, an adaptive array antenna system suitable for this LEO-SAT is presented.

POLIURETANOS BASEADOS EM ÓLEO DE MAMONA

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Heliberto José Limberger

2013-12-01

Full Text Available Neste trabalho de revisão foram apresentadas as principais características do óleo de mamona e de poliuretanos (PUs obtidos a partir deste, descrevendo os métodos de síntese e obtenção empregados. Buscou-se reunir informações sobre novas tendências na área, bem como possíveis aplicações para este tipo de polímero considerando as diferentes propriedades que pode apresentar. PUs obtidos a partir de óleo de mamona podem ser aplicados nas áreas de construção civil, medicina, de materiais e de adesivos, apresentando a vantagem de serem oriundos de fonte renovável e muitas vezes serem biodegradáveis.

Impact of N-plasma and Ga-irradiation on MoS2 layer in molecular beam epitaxy

Science.gov (United States)

Mishra, Pawan; Tangi, Malleswararao; Ng, Tien Khee; Hedhili, Mohamed Nejib; Anjum, Dalaver H.; Alias, Mohd Sharizal; Tseng, Chien-Chih; Li, Lain-Jong; Ooi, Boon S.

2017-01-01

Recent interest in two-dimensional materials has resulted in ultra-thin devices based on the transfer of transition metal dichalcogenides (TMDs) onto other TMDs or III-nitride materials. In this investigation, we realized p-type monolayer (ML) MoS2, and intrinsic GaN/p-type MoS2 heterojunction by the GaN overgrowth on ML-MoS2/c-sapphire using the plasma-assisted molecular beam epitaxy. A systematic nitrogen plasma ( N2 * ) and gallium (Ga) irradiation studies are employed to understand the individual effect on the doping levels of ML-MoS2, which is evaluated by micro-Raman and high-resolution X-Ray photoelectron spectroscopy (HRXPS) measurements. With both methods, p-type doping was attained and was verified by softening and strengthening of characteristics phonon modes E2 g 1 and A 1 g from Raman spectroscopy. With adequate N2 * -irradiation (3 min), respective shift of 1.79 cm-1 for A 1 g and 1.11 cm-1 for E2 g 1 are obtained while short term Ga-irradiated (30 s) exhibits the shift of 1.51 cm-1 for A 1 g and 0.93 cm-1 for E2 g 1 . Moreover, in HRXPS valence band spectra analysis, the position of valence band maximum measured with respect to the Fermi level is determined to evaluate the type of doping levels in ML-MoS2. The observed values of valance band maximum are reduced to 0.5, and 0.2 eV from the intrinsic value of ≈1.0 eV for N2 * - and Ga-irradiated MoS2 layers, which confirms the p-type doping of ML-MoS2. Further p-type doping is verified by Hall effect measurements. Thus, by GaN overgrowth, we attained the building block of intrinsic GaN/p-type MoS2 heterojunction. Through this work, we have provided the platform for the realization of dissimilar heterostructure via monolithic approach.

Eestikeelseid filosoofiaraamatuid oodates / Leo Luks, Margus Ott

Index Scriptorium Estoniae

Luks, Leo, 1976-

2016-01-01

Möödunud aastal ilmus kaks algupärast eestikeelset filosoofiamonograafiat - Margus Oti "Vägi" ja Leo Luksi "Nihilism ja kirjandus". Nende autorid arutlevad vestluses, miks on filosoofiaraamatuid nii vähe

Desempenho na barra de tração de um trator agrícola de pneus, alimentado com misturas de óleo diesel e óleo de soja reutilizado

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Wagner da Cunha Siqueira

2013-12-01

Full Text Available O petróleo é a principal fonte de energia para motores de combustão interna, possibilitando sua transformação em energia mecânica. A dependência do petróleo conduz à necessidade de alternativas, mediante o cultivo de matérias-primas renováveis. Os problemas atuais são os custos dos biocombustíveis, que são maiores que dos derivados do petróleo, e o fato de que não existem muitos motores de combustão adequados ao uso de óleos vegetais. Em vista disso, são necessárias mais investigações quanto às técnicas de produção e de refino dos biocombustíveis e, ainda, à adequação de motores ao uso de óleos vegetais, para que estes possam ser uma alternativa viável. O objetivo deste trabalho foi caracterizar as diferentes misturas e avaliar o desempenho de um trator agrícola de pneus, utilizando misturas de óleo Diesel (OD com óleo de soja reutilizável (OSR. Primeiramente, foi realizado um estudo de densidade, viscosidade das misturas e comportamento da temperatura do OD no sistema de alimentação de combustível no motor. Após as análises, verificou-se, por meio de ensaios na barra de tração, o desempenho das misturas de OD e OSR. As principais conclusões deste trabalho foram: a densidade e viscosidade das misturas sofrem variações com o aumento da quantidade de OSR e com a variação da temperatura. Para as avaliações na barra de tração, os melhores resultados observados no rendimento do trator foram verificados com o aumento das percentagens de mistura (25% OSR, para carga N, 25, 75 e 100% OSR, para a quarta marcha, como carga, e 75 e 100% OSR, para a terceira, segunda e primeira marcha, como carga.

Materials selection for long life in LEO: a critical evaluation of atomic oxygen testing with thermal atom systems

International Nuclear Information System (INIS)

Koontz, S.L.; Kuminecz, J.; Leger, L.; Nordine, P.

1988-01-01

The use of thermal atom test methods as a materials selection and screening technique for low-Earth orbit (LEO) spacecraft is critically evaluated. The chemistry and physics of thermal atom environments are compared with the LEO environment. The relative reactivities of a number of materials determined to be in thermal atom environments are compared to those observed in LEO and in high quality LEO simulations. Reaction efficiencies measured in a new type of thermal atom apparatus are one-hundredth to one-thousandth those observed in LEO, and many materials showing nearly identical reactivities in LEO show relative reactivities differing by as much as a factor of 8 in thermal atom systems. A simple phenomenological kinetic model for the reaction of oxygen atoms with organic materials can be used to explain the differences in reactivity in different environments. Certain specific thermal test environments can be used as reliable materials screening tools. Using thermal atom methods to predict material lifetime in LEO requires direct calibration of the method against LEO data or high quality simulation data for each material

Dusp16 Deficiency Causes Congenital Obstructive Hydrocephalus and Brain Overgrowth by Expansion of the Neural Progenitor Pool

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Ksenija Zega

2017-11-01

Full Text Available Hydrocephalus can occur in children alone or in combination with other neurodevelopmental disorders that are often associated with brain overgrowth. Despite the severity of these disorders, the molecular and cellular mechanisms underlying these pathologies and their comorbidity are poorly understood. Here, we studied the consequences of genetically inactivating in mice dual-specificity phosphatase 16 (Dusp16, which is known to negatively regulate mitogen-activated protein kinases (MAPKs and which has never previously been implicated in brain development and disorders. Mouse mutants lacking a functional Dusp16 gene (Dusp16−/− developed fully-penetrant congenital obstructive hydrocephalus together with brain overgrowth. The midbrain aqueduct in Dusp16−/− mutants was obstructed during mid-gestation by an expansion of neural progenitors, and during later gestational stages by neurons resulting in a blockage of cerebrospinal fluid (CSF outflow. In contrast, the roof plate and ependymal cells developed normally. We identified a delayed cell cycle exit of neural progenitors in Dusp16−/− mutants as a cause of progenitor overproliferation during mid-gestation. At later gestational stages, this expanded neural progenitor pool generated an increased number of neurons associated with enlarged brain volume. Taken together, we found that Dusp16 plays a critical role in neurogenesis by balancing neural progenitor cell proliferation and neural differentiation. Moreover our results suggest that a lack of functional Dusp16 could play a central role in the molecular mechanisms linking brain overgrowth and hydrocephalus.

Organometallic vapor-phase epitaxy theory and practice

CERN Document Server

Stringfellow, Gerald B

1989-01-01

Here is one of the first single-author treatments of organometallic vapor-phase epitaxy (OMVPE)--a leading technique for the fabrication of semiconductor materials and devices. Also included are metal-organic molecular-beam epitaxy (MOMBE) and chemical-beam epitaxy (CBE) ultra-high-vacuum deposition techniques using organometallic source molecules. Of interest to researchers, students, and people in the semiconductor industry, this book provides a basic foundation for understanding the technique and the application of OMVPE for the growth of both III-V and II-VI semiconductor materials and the

Epitaxial-graphene/graphene-oxide junction: an essential step towards epitaxial graphene electronics.

Science.gov (United States)

Wu, Xiaosong; Sprinkle, Mike; Li, Xuebin; Ming, Fan; Berger, Claire; de Heer, Walt A

2008-07-11

Graphene-oxide (GO) flakes have been deposited to bridge the gap between two epitaxial-graphene electrodes to produce all-graphene devices. Electrical measurements indicate the presence of Schottky barriers at the graphene/graphene-oxide junctions, as a consequence of the band gap in GO. The barrier height is found to be about 0.7 eV, and is reduced after annealing at 180 degrees C, implying that the gap can be tuned by changing the degree of oxidation. A lower limit of the GO mobility was found to be 850 cm2/V s, rivaling silicon. In situ local oxidation of patterned epitaxial graphene has been achieved.

Preparation and Characterization of Epitaxial VO2 Films on Sapphire Using Postepitaxial Topotaxy Route via Epitaxial V2O3 Films

Science.gov (United States)

Yamaguchi, Iwao; Manabe, Takaaki; Tsuchiya, Tetsuo; Nakajima, Tomohiko; Sohma, Mitsugu; Kumagai, Toshiya

2008-02-01

Epitaxial VO2 films were prepared on the C-planes of α-Al2O3 substrates by a metal organic deposition (MOD) process. It was difficult to obtain the single phase of (010)M-oriented VO2 films, in which the subscript M refers to the monoclinic indices, by the heat treatment of amorphous precursor films in the VO2-stable region after the pyrolysis of the coating solution. The product films consisted of discontinuous circular grains of 1-2 µm size on the substrate surface. Therefore, we prepared the (010)M-oriented epitaxial VO2 films using postepitaxial topotaxy (PET), that is, topotactic oxidation of (0001)-oriented epitaxial V2O3 films. First, epitaxial V2O3(0001) films were obtained by MOD starting with a vanadium naphthenate solution. Second, the epitaxial V2O3(0001) films were topotactically oxidized at 500 °C in an Ar-O2 gas mixture with pO2 = 10-4 atm to obtain (010)M-oriented epitaxial VO2 films. The epitaxial relationships were VO2(010)M ∥ α-Al2O3(0001) and VO2[100]M ∥ α-Al2O3[0110], [1010], [1100]. The VO2(010)M films exhibited metal-semiconductor transitions with hysteresis loops at 60-80 °C. The resistivity change before and after the transition of the VO2(010)M film oxidized for 6 h was three orders of magnitude.

Long-term behavior of stellar flare activity in AD Leo

International Nuclear Information System (INIS)

Pettersen, B.R.

1984-01-01

AD Leo is a dM4e solar neighborhood red dwarf on the main sequence. It has an effective temperature of 3500 0 K, radius of 0.44 R/sub solar/ and a bolomeric luminosity of 0.024 L/sub solar/. The mass-luminosity relation implies a mass of 0.44 M/sub solar/. Photometry of starspots indicates a rotation period of 2.7 days implying that the rotation axis of AD Leo is inclined 38 0 to the line of sight

Systematic Review and Meta-Analysis: Prevalence of Small Intestinal Bacterial Overgrowth in Chronic Liver Disease.

Science.gov (United States)

Shah, Ayesha; Shanahan, Erin; Macdonald, Graeme A; Fletcher, Linda; Ghasemi, Pegah; Morrison, Mark; Jones, Mike; Holtmann, Gerald

2017-11-01

The authors conducted a meta-analysis of the prevalence of small intestinal bacterial overgrowth (SIBO) in patients with chronic liver disease (CLD) and controls. Using the search terms "small intestinal bacterial overgrowth (SIBO)" and "chronic liver disease (CLD)" or "cirrhosis," 19 case-control studies were identified. Utilizing breath tests, the prevalence of SIBO in CLD was 35.80% (95% CI, 32.60-39.10) compared with 8.0% (95% CI, 5.70-11.00) in controls. Using culture techniques, the prevalence was 68.31% (95% CI, 59.62-76.00) in CLD patients as compared with 7.94% (95% CI, 3.44-12.73) in controls. No difference between cirrhotic and noncirrhotic patients was found. SIBO is significantly more frequent in CLD patients as compared with controls. The association of SIBO and CLD was not confined to patients with advanced CLD, suggesting that SIBO is not a consequence of advanced liver disease but may play a role in the progression of CLD. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

GaN/NbN epitaxial semiconductor/superconductor heterostructures

Science.gov (United States)

Yan, Rusen; Khalsa, Guru; Vishwanath, Suresh; Han, Yimo; Wright, John; Rouvimov, Sergei; Katzer, D. Scott; Nepal, Neeraj; Downey, Brian P.; Muller, David A.; Xing, Huili G.; Meyer, David J.; Jena, Debdeep

2018-03-01

Epitaxy is a process by which a thin layer of one crystal is deposited in an ordered fashion onto a substrate crystal. The direct epitaxial growth of semiconductor heterostructures on top of crystalline superconductors has proved challenging. Here, however, we report the successful use of molecular beam epitaxy to grow and integrate niobium nitride (NbN)-based superconductors with the wide-bandgap family of semiconductors—silicon carbide, gallium nitride (GaN) and aluminium gallium nitride (AlGaN). We apply molecular beam epitaxy to grow an AlGaN/GaN quantum-well heterostructure directly on top of an ultrathin crystalline NbN superconductor. The resulting high-mobility, two-dimensional electron gas in the semiconductor exhibits quantum oscillations, and thus enables a semiconductor transistor—an electronic gain element—to be grown and fabricated directly on a crystalline superconductor. Using the epitaxial superconductor as the source load of the transistor, we observe in the transistor output characteristics a negative differential resistance—a feature often used in amplifiers and oscillators. Our demonstration of the direct epitaxial growth of high-quality semiconductor heterostructures and devices on crystalline nitride superconductors opens up the possibility of combining the macroscopic quantum effects of superconductors with the electronic, photonic and piezoelectric properties of the group III/nitride semiconductor family.

Strain-Modulated Epitaxy

National Research Council Canada - National Science Library

Brown, April

1999-01-01

Strain-Modulated Epitaxy (SME) is a novel approach, invented at Georgia Tech, to utilize subsurface stressors to control strain and therefore material properties and growth kinetics in the material above the stressors...

Estudo experimental e de modelagem da fluidodinâmica de sistemas água/óleo

OpenAIRE

Fiorese, Eliana Kátia

2004-01-01

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Química Diversas operações e procedimentos na indústria do petróleo estão relacionados ao deslocamento imiscível de um fluido por outro, podendo-se citar: a elevação natural e artificial do óleo a partir dos poços, o bombeamento através de dutos de óleos de viscosidade elevada mediante a injeção conjunta de água e a recuperação secundária de petróleo. A eficiência de...

Surface chemistry and growth mechanisms studies of homo epitaxial (1 0 0) GaAs by laser molecular beam epitaxy

International Nuclear Information System (INIS)

Yan Dawei; Wu Weidong; Zhang Hong; Wang Xuemin; Zhang Hongliang; Zhang Weibin; Xiong Zhengwei; Wang Yuying; Shen Changle; Peng Liping; Han Shangjun; Zhou Minjie

2011-01-01

In this paper, GaAs thin film has been deposited on thermally desorbed (1 0 0) GaAs substrate using laser molecular beam epitaxy. Scanning electron microscopy, in situ reflection high energy electron diffraction and in situ X-ray photoelectron spectroscopy are applied for evaluation of the surface morphology and chemistry during growth process. The results show that a high density of pits is formed on the surface of GaAs substrate after thermal treatment and the epitaxial thin film heals itself by a step flow growth, resulting in a smoother surface morphology. Moreover, it is found that the incorporation of As species into GaAs epilayer is more efficient in laser molecular beam epitaxy than conventional molecular beam epitaxy. We suggest the growth process is impacted by surface chemistry and morphology of GaAs substrate after thermal treatment and the growth mechanisms are discussed in details.

Semiconductors and semimetals epitaxial microstructures

CERN Document Server

Willardson, Robert K; Beer, Albert C; Gossard, Arthur C

1994-01-01

Newly developed semiconductor microstructures can now guide light and electrons resulting in important consequences for state-of-the-art electronic and photonic devices. This volume introduces a new generation of epitaxial microstructures. Special emphasis has been given to atomic control during growth and the interrelationship between the atomic arrangements and the properties of the structures.Key Features* Atomic-level control of semiconductor microstructures* Molecular beam epitaxy, metal-organic chemical vapor deposition* Quantum wells and quantum wires* Lasers, photon(IR)detectors, heterostructure transistors

Efeito de óleos essenciais como alternativa no controle de Colletotrichum gloeosporioides, em pimenta

Directory of Open Access Journals (Sweden)

Rosa Maria Souto de Sousa

2012-03-01

Full Text Available Fungos do gênero Colletotrichum causam doenças conhecidas como antracnose. Métodos alternativos que sejam eficientes e menos agressivos vêm sendo amplamente testados. Dentre estes, surge o interesse pela utilização de óleos essenciais extraídos de vegetais. O presente trabalho teve como objetivo avaliar o efeito de óleos essenciais de eucalipto, copaíba, andiroba, babaçu, coco, neem, semente de uva, amêndoa, hortelã e pau rosa, em diferentes concentrações sobre o fungo Colletotrichum gloeosporioides, in vitro e em frutos de pimenta em pós colheita. O experimento in vitro foi realizado utilizando-se cinco concentrações (0,2; 0,4; 0,6; 0,8 e 1,0% dos dez óleos misturados ao meio de cultura BDA. As variáveis analisadas foram a taxa de crescimento micelial e o índice de velocidade de crescimento micelial (IVCM. O ensaio em pós-colheita foi feito com imersão dos frutos de pimenta por 5 minutos, nos mesmos óleos utilizados no experimento anterior, usando-se a maior concentração. O fungo C. gloeosporioides foi inoculado, através de ferimento, logo após a imersão dos frutos. As avaliações foram realizadas diariamente através de medição do diâmetro das colônias e das lesões, tomando-se duas medições em sentidos diametralmente opostos. Pode-se observar que no experimento in vitro todos os óleos, com exceção dos óleos de babaçu, semente de uva e amêndoa, tiveram excelentes resultados inibindo o crescimento do fungo. No resultado obtido em pós-colheita foi observado que apenas o óleo de babaçu não foi eficiente em reduzir o desenvolvimento da lesão de antracnose. Dados relevantes foram observados para os óleos de semente de uva e amêndoa, que não apresentaram efeito direto sobre o fungo in vitro, porém no tratamento pós-colheita apresentaram bons resultados, reduzindo a lesão causada por C. gloeosporioides, sugerindo assim que estes óleos possam ser utilizados como indutores de resistência em frutos

A novel aromatic oil compound inhibits microbial overgrowth on feet: a case study

Directory of Open Access Journals (Sweden)

Misner Bill D

2007-07-01

Full Text Available Abstract Background Athlete's Foot (Tinea pedis is a form of ringworm associated with highly contagious yeast-fungi colonies, although they look like bacteria. Foot bacteria overgrowth produces a harmless pungent odor, however, uncontrolled proliferation of yeast-fungi produces small vesicles, fissures, scaling, and maceration with eroded areas between the toes and the plantar surface of the foot, resulting in intense itching, blisters, and cracking. Painful microbial foot infection may prevent athletic participation. Keeping the feet clean and dry with the toenails trimmed reduces the incidence of skin disease of the feet. Wearing sandals in locker and shower rooms prevents intimate contact with the infecting organisms and alleviates most foot-sensitive infections. Enclosing feet in socks and shoes generates a moisture-rich environment that stimulates overgrowth of pungent both aerobic bacteria and infectious yeast-fungi. Suppression of microbial growth may be accomplished by exposing the feet to air to enhance evaporation to reduce moistures' growth-stimulating effect and is often neglected. There is an association between yeast-fungi overgrowths and disabling foot infections. Potent agents virtually exterminate some microbial growth, but the inevitable presence of infection under the nails predicts future infection. Topical antibiotics present a potent approach with the ideal agent being one that removes moisture producing antibacterial-antifungal activity. Severe infection may require costly prescription drugs, salves, and repeated treatment. Methods A 63-y female volunteered to enclose feet in shoes and socks for 48 hours. Aerobic bacteria and yeast-fungi counts were determined by swab sample incubation technique (1 after 48-hours feet enclosure, (2 after washing feet, and (3 after 8-hours socks-shoes exposure to a aromatic oil powder-compound consisting of arrowroot, baking soda, basil oil, tea tree oil, sage oil, and clove oil. Conclusion

Interface relaxation and band gap shift in epitaxial layers

Directory of Open Access Journals (Sweden)

Ziming Zhu

2012-12-01

Full Text Available Although it is well known that the interface relaxation plays the crucial role for the electronic properties in semiconductor epitaxial layers, there is lack of a clear definition of relationship between interfacial bond-energy variation and interface bond-nature-factor (IBNF in epitaxial layers before and after relaxation. Here we establish an analytical method to shed light on the relationship between the IBNF and the bond-energy change, as well as the relation with band offset in epitaxial layers from the perspective of atomic-bond-relaxation consideration and continuum mechanics. The theoretical predictions are consistent with the available evidences, which provide an atomistic understanding on underlying mechanism of interface effect in epitaxial nanostructures. Thus, it will be helpful for opening up to tailor physical-chemical properties of the epitaxial nanostructures to the desired specifications.

Epitaxial Graphene: A New Material for Electronics

Science.gov (United States)

de Heer, Walt A.

2007-10-01

Graphene multilayers are grown epitaxially on single crystal silicon carbide. This system is composed of several graphene layers of which the first layer is electron doped due to the built-in electric field and the other layers are essentially undoped. Unlike graphite the charge carriers show Dirac particle properties (i.e. an anomalous Berry's phase, weak anti-localization and square root field dependence of the Landau level energies). Epitaxial graphene shows quasi-ballistic transport and long coherence lengths; properties that may persists above cryogenic temperatures. Paradoxically, in contrast to exfoliated graphene, the quantum Hall effect is not observed in high mobility epitaxial graphene. It appears that the effect is suppressed due to absence of localized states in the bulk of the material. Epitaxial graphene can be patterned using standard lithography methods and characterized using a wide array of techniques. These favorable features indicate that interconnected room temperature ballistic devices may be feasible for low dissipation high-speed nano-electronics.

Potencial antifúngico e toxicidade de óleos essenciais da família lamiaceae

OpenAIRE

Rosema Santin

2013-01-01

Plantas medicinais e óleos essenciais representam um importante papel na terapêutica, tanto na cura como também na prevenção de diferentes enfermidades, sendo esta prática medicinal uma das mais antigas formas de tratamento. Devido à utilização dos óleos essenciais na terapêutica e a importância do conhecimento do pontencial de toxicidade destes, objetivou-se: (i) identificar os principais componentes químicos dos óleos essenciais de Origanum vulgare (orégano), Origanum majorana (manjerona) e...

Overgrowth of fungi (endolithic hypermycosis) associated with multifocal to diffuse distinct amorphous dark discoloration of corals in the Indo-Pacific

Science.gov (United States)

Work, Thierry M.; Aeby, G.S.; Stanton, F.G.; Fenner, D.

2008-01-01

Coral disease surveys in American Samoa and Hawai‘i revealed colonies with a distinct dark discoloration affecting 20–60% of the colony surface (Fig. 1a). In some cases, tissue loss with algal infiltration was present within discolored areas. On microscopy, these lesions had marked overgrowth of the coral skeleton and tissues with septate branching structures that stained positive with Grocott’s Methenamine Silver (fungal hyphae) accompanied by necrosis and fragmentation of coral tissues (Fig. 1b). We have observed this condition grossly and microscopically in Pavona varians, Psammocora nierstraszi, and Montipora sp. in American Samoa and in Pavona maldivensis and P. varians in Hawai‘i. This condition resembles Dark Spots Disease from the Caribbean (Solano et al. 1993) that also shows endolithic hypermycosis (Galloway et al. 2007), suggesting that the association between dark discoloration of corals and overgrowth of endolithic fungi may be common (Western Atlantic, Indo-Pacific). Based on gross and microscopic morphology, tissue atrophy may precede overgrowth of endolithic fungi, but this awaits confirmation through systematic studies that monitor the development of lesions over time (pathogenesis). Using standardized terminology (Work and Aeby 2006) to describe lesions facilitates regional comparisons of coral disease.

Analysis of changes in gingival contour from three-dimensional co-ordinate data in subjects with drug-induced gingival overgrowth.

Science.gov (United States)

Thomason, J M; Ellis, J S; Jovanovski, V; Corson, M; Lynch, E; Seymour, R A

2005-10-01

This aim of this study was to develop and assess a technique that could be used to assess accurately the gingival volume changes seen in drug-induced gingival overgrowth by the analysis of data obtained from an entire gingival surface by means of three-dimensional imaging. Stone dental models of patients before and after gingivectomy procedures were digitized with a laser scanner and then regenerated as computer models constructed from the acquired three-dimensional co-ordinate data. A comparison of superposed "before" and "after" surfaces was undertaken to assess and accurately quantify changes in gingival contour. The mean vertical tissue reduction varied from 1.58 to 2.56 mm in the four study subjects and individual differences are shown. The maximum thickness of removed buccal gingival overgrowth was found to range between 1.20 and 3.40 mm. The volume of tissue removed from each inter-dental papilla ranged from 4.2 to 46.1 mm3 and the mean volume of the papilla removed from each subject+/-SD values was 24.8+/-13.1 mm3. This method will measure changes in gingival tissues to within 60 microm in one plane, making it ideal for the assessment of longitudinal changes in gingival contour as seen in the development of gingival overgrowth, its recurrence after surgery or the changes in volume brought about by surgery.

Actividad anticaries de una crema dental con propóleos

OpenAIRE

Estela Gispert Abreu; Elena Cantillo Estrada; Aracelys Rivero López; Marela Padrón Illance

2000-01-01

Por muestreo aleatorio simple se seleccionaron 50 escolares con antecedentes de alta infección por Streptococcus mutans, para verificar la actividad anticaries de una crema dental que contiene 0,8 de extracto de propóleo blando. Se perdieron del estudio a 7 escolares por inasistencia y traslados. Se crearon 2 grupos: uno control (n=19) que se cepilló con una crema dental placebo y otro tratamiento (n=24) que se cepilló con la crema dental de propóleo. Entre ambos grupos no había diferencia si...

América Latina: petróleo y conflicto

Directory of Open Access Journals (Sweden)

Luis Humberto Hernández

2008-01-01

Full Text Available En el actual escenario conflictivo mundial energético presentamos la siguiente reflexión sobre la situación petrolera de América Latina a partir de su discurrir pasado y la situación actual. Se ubica inicialmente una breve historia regional del petróleo en el mundo a partir de los hechos fundamentales que le dan razón a cada una de las ocho regiones petroleras existentes, concentrando la reseña en América Latina, acompañada de un balance del estado económico y político actual del petróleo en América Latina.

Efeito de enzimas hidrolíticas no comportamento reológico do óleo de palma cru

Directory of Open Access Journals (Sweden)

FREITAS Suely P.

1998-01-01

Full Text Available No processamento tradicional de extração de óleo de palma, uma quantidade substancial do produto é perdida na fibra - durante a etapa de prensagem do fruto - e na borra - durante a etapa de clarificação do óleo cru. A viscosidade deste constitui a principal dificuldade de separação do óleo dos demais componentes da mistura. A eficiência de recuperação do óleo é usualmente melhorada por adição de água, no tanque de clarificação. Neste trabalho avaliou-se os efeitos da diluição e do tratamento enzimático no comportamento reológico do óleo de palma cru. Estes dados são importantes para estimar a velocidade de separação do óleo nos tanques de clarificação e/ou nos decanters das usinas comerciais. O óleo cru utilizado neste estudo foi recolhido em uma unidade comercial sendo composto de 65% de água, 30% de óleo e 5% de sólidos. A hidrólise enzimática foi conduzida usando como agentes hidrolisantes uma enzima comercial (viscozyme da Novo Nordisk e um preparado enzimático produzido no CTAA. Pode-se constatar que quanto mais diluída a amostra maior é a redução na viscosidade após a hidrólise enzimática. Para uma taxa de deformação fixa em 6s-1, o tratamento enzimático do óleo cru a 60°C reduziu a viscosidade do mesmo em cerca de 29% enquanto a adição de 20% de água em cerca de 35%. A combinação da diluição com 20% de água seguida de tratamento enzimático reduziu a viscosidade do óleo cru em cerca de 75%.

MOVPE gallium-nitride nanostructures fabricated on ZnO nanorod templates grown from aqueous chemical solution

Energy Technology Data Exchange (ETDEWEB)

Fuendling, Soenke; Li Shunfeng; Postels, Bianca; Al-Suleiman, Mohamed; Wehmann, Hergo-Heinrich; Bakin, Andrey; Waag, Andreas, E-mail: s.fuendling@tu-bs.de [Institut fuer Halbleitertechnik, Technische Universitaet Braunschweig, 38096 Braunschweig (Germany)

2009-11-15

Concerning optoelectronic devices fabricated by epitaxial methods, the combination of ZnO and GaN has promising aspects regarding their good optical properties and a relatively good lattice matching between both as compared to other foreign substrates like sapphire or silicon. Moreover ZnO nanopillar arrays may serve as a template for GaN nanopillar fabrication or for high quality GaN layers by lateral overgrowth of the ZnO nanopillars. In this work, we investigate the combination of two very different growth methods - aqueous chemical low temperature growth (ACG) for the ZnO nanopillar templates on silicon substrates and metalorganic vapor phase epitaxy (MOVPE) for the GaN overgrowth - in order to show to which extent the very cost efficient ZnO templates suit the high demands of GaN MOVPE. By a combination of annealing and photoluminescence experiments we show that the properties of the heterostructures change significantly with temperature.

Epitaxial growth and new phase of single crystal Dy by molecular beam epitaxy

International Nuclear Information System (INIS)

Yang, Kai-Yueh; Homma, Hitoshi; Schuller, I.K.

1987-09-01

We have grown two novel epitaxial phases of dysprosium (Dy) on vanadium (V) by molecular beam epitaxy technique. Surface and bulk structures are studied by in-situ reflection high energy electron diffraction (RHEED) and x-ray diffraction techniques. The new hcp phases are ∼4% expanded uniformly in-plane (0001), and ∼9% and ∼4% expanded out of plane along the c-axes for non-interrupted and interrupted deposition case, respectively. We also observed (2 x 2), (3 x 3), and (4 x 4) Dy surface reconstruction patterns and a series of transitions as the Dy film thickness increases. 12 refs., 3 figs

Estruturação de óleo de palma e emulsões utilizando óleo de palma totalmente hidrogenado e lecitina de soja

OpenAIRE

Valéria da Silva Santos

2014-01-01

Resumo: O óleo de palma (PO) destaca-se por ser uma matéria-prima com grande potencial de aplicação em diversos produtos. Porém, quando aplicado de maneira isolada, apresenta cristalização lenta, gerando problemas para a indústria de alimentos. A fim de acelerar a cristalização utilizam-se compostos que podem, além de contribuir para a redução do período de indução, atuar como agentes estruturantes, atual foco em desenvolvimento na área de óleos e gorduras. Este estudo tem por objetivos avali...

Reciclo-óleo: do óleo de cozinha ao sabão ecológico, um projeto de educação ambiental

OpenAIRE

Maria Isabel Morgan Martins; Fábio Renê Klagenberg Mesdes; Caroline Soster; Eliane Fraga; Ana Maria Pujol Vieira dos Santos; Nadia Teresinha Schoreder

2016-01-01

O consumo de óleo faz parte do dia-a-dia das famílias, restaurantes, indústrias e com ele o descarte incorreto do óleo de cozinha usado (OCU) se torna um grave problema ambiental. Quando despejado no lixo comum impermeabiliza e contamina o solo, porque a decomposição aumenta o efeito estufa, na rede de esgoto compromete as tubulações das residências e das cidades e ao atingir os rios forma uma película na água que impede a passagem de luz e oxigênio a flora e a fauna aquática. Objetivo: é pro...

Point defect balance in epitaxial GaSb

International Nuclear Information System (INIS)

Segercrantz, N.; Slotte, J.; Makkonen, I.; Kujala, J.; Tuomisto, F.; Song, Y.; Wang, S.

2014-01-01

Positron annihilation spectroscopy in both conventional and coincidence Doppler broadening mode is used for studying the effect of growth conditions on the point defect balance in GaSb:Bi epitaxial layers grown by molecular beam epitaxy. Positron annihilation characteristics in GaSb are also calculated using density functional theory and compared to experimental results. We conclude that while the main positron trapping defect in bulk samples is the Ga antisite, the Ga vacancy is the most prominent trap in the samples grown by molecular beam epitaxy. The results suggest that the p–type conductivity is caused by different defects in GaSb grown with different methods.

CARACTERIZAÇÃO QUÍMICA E ATIVIDADE MUTAGÊNICA DO ÓLEO ESSENCIAL DE Lippia alba

Directory of Open Access Journals (Sweden)

Thammyres de Assis Alves

2017-01-01

Full Text Available Os óleos essenciais são substâncias voláteis que vêm despertando interesse no setor agrícola, devido o grande potencial que possuem no controle de pragas. Assim, objetivo deste trabalho foi determinar a composição química do óleo essencial de folhas de Lippia alba e avaliar o seu potencial mutagênico. Para isso, o óleo essencial foi obtido por hidrodestilação, utilizando um aparelho do tipo Clevenger, seus constituintes químicos foram analisados por meio da cromatografia em fase gasosa com detector de ionização de chama (CG-DIC e de espectrometria de massas (CG-EM. Os compostos majoritários encontrados foram: geranial (29,83%, neral (20,71% e óxido de cariofileno (19,26%. A toxicidade do óleo essencial de L. alba foi avaliado em sementes de Lactuca sativa. O óleo essencial de L. alba inibiu 100% o crescimento radicular das sementes de L. sativa nas concentrações de 0,720% e 0,360% (m v-1. Nas outras concentrações testadas (0,180%, 0,090%, 0,045%, o óleo essencial apresentou um decréscimo no efeito de inibição conforme diminuição de sua concentração. Logo, o óleo essencial de L. alba possui potencial a ser usado como bioherbicida.

BAVP: Blockchain-Based Access Verification Protocol in LEO Constellation Using IBE Keys

OpenAIRE

Wei, Songjie; Li, Shuai; Liu, Peilong; Liu, Meilin

2018-01-01

LEO constellation has received intensive research attention in the field of satellite communication. The existing centralized authentication protocols traditionally used for MEO/GEO satellite networks cannot accommodate LEO satellites with frequent user connection switching. This paper proposes a fast and efficient access verification protocol named BAVP by combining identity-based encryption and blockchain technology. Two different key management schemes with IBE and blockchain, respectively...

Position-controlled epitaxial III-V nanowires on silicon

Energy Technology Data Exchange (ETDEWEB)

Roest, Aarnoud L; Verheijen, Marcel A; Wunnicke, Olaf; Serafin, Stacey; Wondergem, Harry; Bakkers, Erik P A M [Philips Research Laboratories, Professor Holstlaan 4, 5656 AA Eindhoven (Netherlands); Kavli Institute of NanoScience, Delft University of Technology, PO Box 5046, 2600 GA Delft (Netherlands)

2006-06-14

We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the VLS mechanism with laser ablation as well as metal-organic vapour phase epitaxy. The hetero-epitaxial growth of the III-V nanowires on silicon was confirmed with x-ray diffraction pole figures and cross-sectional transmission electron microscopy. We show preliminary results of two-terminal electrical measurements of III-V nanowires grown on silicon. E-beam lithography was used to predefine the position of the nanowires.

Position-controlled epitaxial III-V nanowires on silicon

International Nuclear Information System (INIS)

Roest, Aarnoud L; Verheijen, Marcel A; Wunnicke, Olaf; Serafin, Stacey; Wondergem, Harry; Bakkers, Erik P A M

2006-01-01

We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the VLS mechanism with laser ablation as well as metal-organic vapour phase epitaxy. The hetero-epitaxial growth of the III-V nanowires on silicon was confirmed with x-ray diffraction pole figures and cross-sectional transmission electron microscopy. We show preliminary results of two-terminal electrical measurements of III-V nanowires grown on silicon. E-beam lithography was used to predefine the position of the nanowires

Passive Optical Link Budget for LEO Space Surveillance

Science.gov (United States)

Wagner, P.; Hasenohr, T.; Hampf, D.; Sproll, F.; Humbert, L.; Rodmann, J.; Riede, W.

The rising space debris population is becoming an increasing risk for space assets. Even objects with the size of 10mm can cause major damages to active spacecraft. Especially the orbits around 800km high are densely populated with space debris objects. To assess the risk of collisions with active satellites, the Earth orbits need to be surveyed permanently. Space debris laser ranging systems for example can deliver highly accurate positional data for precise orbit determination. Therefor a priori information about the objects coarse trajectory is needed. Such initial orbit information can be provided by wide angle optical sensors. The Institute of Technical Physics at the German Aerospace Center in Stuttgart runs an observatory to perform passive as well as laser optical measurements to LEO objects. In order to detect unknown objects, a wide-angle imaging system with a field of view in the range of 5° to 15° equipped with an astronomical CCD camera and a commercial off the shelf (COTS) lens was designed to continuously observe the night sky for LEO objects. This paper presents the passive optical link budget for observing LEO objects to show the benefits and limits of the physical performance of an optical surveillance system. A compact COTS system is able to detect objects with a couple of decimeters in size while a large aperture telescope can detect objects with diameters below 10cm. Additionally, data captured by a passive optical staring system with a 10 cm aperture was analyzed. It is shown that 90% of all objects with a radar cross section larger than 2m² are detected with such a system during twilight conditions. The smallest detected LEO object with this system has a size of 0.32m x 0.32m x 0.26m. These measurements are compared to the developed link budget which allows an estimation of the performance of larger systems.

Rendimento e Características Físicas dos Óleos de Nim (Azadirachta indica e Mamona (Ricinus communis

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Juarez Benigno Paes

Full Text Available A pesquisa objetivou avaliar o rendimento e a viscosidade de óleos de nim (Azadirachta indica e mamona (Ricinus communis. Os frutos de nim foram coletados no Núcleo de Pesquisa do Semiárido, em Patos, Paraíba, e os de mamona, às margens do Rio Espinharas, Patos e em Igaracy, Paraíba. Os frutos foram beneficiados no Laboratório de Tecnologia de Produtos Florestais, em Patos. Foram retiradas amostras de sementes para a determinação do teor de umidade e do rendimento em óleos. Os óleos foram extraídos com álcool etílico absoluto e empregados no preparo de soluções com os óleos de nim e mamona. Determinaram-se a densidade e a viscosidade das soluções. A mamona teve menor teor de umidade e rendimento em óleo que o nim. A densidade e a viscosidade do óleo de nim foram menores que o da mamona. Uma maior quantidade de óleos de mamona proporcionou aumento na densidade e na viscosidade das soluções preparadas.

Effect of LEO cycling on 125 Ah advanced design IPV nickel-hydrogen flight cells - An update

Science.gov (United States)

Smithrick, John J.; Hall, Stephen W.

1991-01-01

An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent potassium hydroxide (KOH) electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel nickel-hydrogen cells is reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH.

Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight cells. An update

Science.gov (United States)

Smithrick, John J.; Hall, Stephen W.

1991-01-01

An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent potassium hydroxide (KOH) electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel nickel-hydrogen cells is reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH.

Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight cells - An update

Science.gov (United States)

Smithrick, John J.; Hall, Stephen W.

1991-01-01

An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent potassium hydroxide (KOH) electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel nickel-hydrogen cells is reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH.

Estudo da composição química de gasóleos comerciais

OpenAIRE

Silva, Filipe Pereira e

2010-01-01

No presente trabalho foram estudadas a composição química em termos percentuais dos compostos PIONA (n-parafinas, isoparafinas, olefinas, naftenos e aromáticos) e algumas propriedades físicas de diferentes classes de gasóleos comerciais utilizados em veículos rodoviários e um gasóleo para aquecimento. O gasóleo, uma fracção do crude, é um composto de extrema complexidade com milhares de diferentes moléculas na sua composição. Dividem-se sobretudo em parafinas (alcanos) lineares ou ramifica...

The LEO PCDU EVO - A Modular and Flexible Concept for Low to Medium Power LEO & Scientific Missions

Directory of Open Access Journals (Sweden)

Lapeña Emilio

2017-01-01

Market trend towards volume & mass reduction, plus new required capabilities (in particular End of Life Passivation and Launch Off to support multiple launch justify the need for a new LEO PCDU EVO generation. This paper will deal with a simple question with no immediate answer: how to save 20% PCDU mass and volume while keeping or improving existing performances.

Can Telescopes Help Leo Satellites Dodge Most Lethal Impacts?

Science.gov (United States)

GUDIEL, ANDREA; Carroll, Joseph; Rowe, David

2018-01-01

Authors: Joseph Carroll and David RoweABSTRACT LEO objects are tracked by radar because it works day and night, in all weather. This fits military interest in potentially hostile objects. There is less interest in objects too small to be credible active threats. But accidental hypervelocity impact by even 5-10 mm objects can disable most LEO satellites. Such “cm-class” objects greatly outnumber objects of military interest, and will cause most accidental impact losses.Under good viewing conditions, a sunlit 5mm sphere with 0.15 albedo at 800 km altitude is a 19th magnitude object. A ground-based 0.5m telescope tracking it against a 20 mag/arcsec2 sky can see it in seconds, and provide 1 million such objects in LEO, nearly all debris fragments, mostly cm-class and at 600-1200 km altitude.Maintaining a ~million-item catalog requires a world-wide network of several dozen telescope sites with several telescopes at each site. Each telescope needs a mount capable of ~1,000,000 fast slews/year without wearing out.The paper discusses recent advances that make such a service far more feasible:1. Automated tasking and remote control of distributed telescope networks,2. Direct-drive mounts that can make millions of fast slews without wearing out,3. Telescope optics with low focal curvature that are in focus across large imagers,4. CMOS imagers with 95% peak QE and 1.5e- noise at 2E8 pix/sec readout rates,5. Methods for uncued detection of most lethal LEO debris (eg., >5 mm at 800 km),6. Initial orbit determination using 3 alt-az fixes made during the discovery pass,7. High-speed photometry to infer debris spin axis, to predict drag area changes,8. Better conjunction predictions using explicit modeling of drag area variations.

Direct Measurements of Island Growth and Step-Edge Barriers in Colloidal Epitaxy

KAUST Repository

Ganapathy, R.

2010-01-21

Epitaxial growth, a bottom-up self-assembly process for creating surface nano- and microstructures, has been extensively studied in the context of atoms. This process, however, is also a promising route to self-assembly of nanometer- and micrometer-scale particles into microstructures that have numerous technological applications. To determine whether atomic epitaxial growth laws are applicable to the epitaxy of larger particles with attractive interactions, we investigated the nucleation and growth dynamics of colloidal crystal films with single-particle resolution. We show quantitatively that colloidal epitaxy obeys the same two-dimensional island nucleation and growth laws that govern atomic epitaxy. However, we found that in colloidal epitaxy, step-edge and corner barriers that are responsible for film morphology have a diffusive origin. This diffusive mechanism suggests new routes toward controlling film morphology during epitaxy.

Variable stars in the Leo A dwarf galaxy (DDO 69)

Science.gov (United States)

Hoessel, John G.; Saha, A.; Krist, John; Danielson, G. Edward

1994-01-01

Observations of the Leo A dwarf galaxy, obtained over the period from 1980 to 1991 are reported. Forty two separate Charge Coupled Devices (CCD) frames were searched for variable stars. A total of 14 suspected variables were found, 9 had sufficient coverage for period determination, and 5 had Cepheid light curves. Four of these stars fit well on a P-L relation and yield a distance modulus, after correction for Galactic foreground extinction, of m-M = 26.74. This corresponds to a distance of 2.2 Mpc, placing Leo A near the Local Group zero-velocity surface.

Óleos e gosduras vegetais: composição e tecnologia

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Luiz Antonio Gioielli

Full Text Available O trabalho apresenta revisão bibliográfica sobre a composição química de óleos e gorduras vegetais, incluindo a classificação de lipídeos, as notações empregadas, os principais ácidos graxos saturados e insaturados e o teor em óleo de matérias-primas vegetais. São ainda enfocados aspectos de produção comercial mundial e brasileira. São apresentados esquemas básicos de processamento industrial, incluindo a preparação da matérias-primas vegetais. São ainda enfocados aspectos de produção comercial mundial e brasileira. São apresentados esquemas básicos de processamento industrial, incluindo a preparação da matéria-prima, a extração do óleo bruto e os métodos de refinação e modificação.

All-epitaxial Co{sub 2}FeSi/Ge/Co{sub 2}FeSi trilayers fabricated by Sn-induced low-temperature epitaxy

Energy Technology Data Exchange (ETDEWEB)

Kawano, M.; Ikawa, M.; Arima, K.; Yamada, S.; Kanashima, T.; Hamaya, K., E-mail: hamaya@ee.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka 560-8531 (Japan)

2016-01-28

We demonstrate low-temperature growth of all-epitaxial Co{sub 2}FeSi/Ge/Co{sub 2}FeSi trilayer structures by developing Sn-induced surfactant-mediated molecular beam epitaxy (SMBE) of Ge on Co{sub 2}FeSi. Despite the growth of a semiconductor on a metal, we verify that the inserted Sn monolayers between Ge and Co{sub 2}FeSi enable to promote the 2D epitaxial growth of Ge up to 5 nm at a T{sub G} of 250 °C. An understanding of the mechanism of the Sn-induced SMBE leads to the achievement of all-epitaxial Co{sub 2}FeSi/Ge/Co{sub 2}FeSi trilayer structures with spin-valve-like magnetization reversals. This study will open a way for vertical-type and high-performance Ge-based spintronics devices.

Epitaxial patterning of thin-films: conventional lithographies and beyond

International Nuclear Information System (INIS)

Zhang, Wei; Krishnan, Kannan M

2014-01-01

Thin-film based novel magnetic and electronic devices have entered a new era in which the film crystallography, structural coherence, and epitaxy play important roles in determining their functional properties. The capabilities of controlling such structural and functional properties are being continuously developed by various physical deposition technologies. Epitaxial patterning strategies further allow the miniaturization of such novel devices, which incorporates thin-film components into nanoscale architectures while keeping their functional properties unmodified from their ideal single-crystal values. In the past decade, epitaxial patterning methods on the laboratory scale have been reported to meet distinct scientific inquires, in which the techniques and processes used differ from one to the other. In this review we summarize many of these pioneering endeavors in epitaxial patterning of thin-film devices that use both conventional and novel lithography techniques. These methods demonstrate epitaxial patterning for a broad range of materials (metals, oxides, and semiconductors) and cover common device length scales from micrometer to sub-hundred nanometer. Whilst we have been motivated by magnetic materials and devices, we present our outlook on developing systematic-strategies for epitaxial patterning of functional materials which will pave the road for the design, discovery and industrialization of next-generation advanced magnetic and electronic nano-devices. (topical review)

Óleo de melaleuca (Melaleuca alternifolia Maiden & Betche, Cheel no controle de cercosporiose em beterraba

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A.D. SOUZA

2015-01-01

Full Text Available RESUMO O óleo volátil da melaleuca (Melaleuca alternifolia Maiden & Betche, Cheel possui atividade antimicrobiana podendo causar efeitos sobre as plantas. Avaliou-se a inibição do óleo em Cercospora beticolaSacc., e seu efeito no aumento da produção e qualidade de raízes de beterraba. As doses foram de 0,13; 0,67; 0,80 e 1,00% do óleo, além das testemunhas composta pelo meio de cultura Batata Dextrose Ágar (BDA no experimento in vitro, e água no experimento in vivo. As plantas foram pulverizadas duas vezes por semana. O delineamento foi inteiramente casualizado, com 4 repetições, e as médias foram comparadas pelo teste Tukey a 5% de probabilidade. O índice de infecção das folhas foi determinado por escala diagramática além do peso e diâmetro das raízes. Os resultados de inibição do crescimento micelial para as doses do óleo foram 0; 56; 87; 83 e 99%, e os índices de infecção: 77,08; 35,62; 21,04; 19,37 e 20,00%, respectivamente, para a testemunha e as doses 0,13; 0,67; 0,80 e 1,00% do óleo. Somente na concentração de 0,80% o óleo proporcionou relação positiva entre o ganho de peso e o diâmetro das raízes. O óleo de Melaleuca foi eficaz no controle de C. beticola e, como consequência, houve produção de raízes de beterraba com melhor desenvolvimento.

GINGIVAL OVERGROWTH INDUCED BY IMMUNOSUPPRESSIVE TREATMENT WITH CYCLOSPORINE A AND MYCOPHENOLATE MOFETIL IN A PATIENT WITH KIDNEY TRANSPLANT – A CASE REPORT AND LITERATURE REVIEW

Directory of Open Access Journals (Sweden)

Daniela Trandafir

2013-07-01

Full Text Available Cyclosporine A, a drug that inhibits the immuneresponse, has been widely used for over 30 years in immunosuppressivetherapy protocols for patient‑recipients ofthe transplanted organs. One of the commonly reportedside effects of Cyclosporine A is gingival overgrowth, withvarying degrees of severity, which may interfere with theaesthetics and normal functions of the oral cavity. Combinationwith other drugs that can recognize the gum tissueas a secondary target organ increases the risk ofdrug‑induced gingival overgrowth. In cases where a lowerdose of Cyclosporine A or conversion to another immunosuppressiveagent (a drug not assigned to such a sideeffect are not possible, the management of severe gingivalovergrowth focuses on surgical excision of the excessivelyproliferated gingival tissue. We report the case of a youngadult with moderate drug‑induced gingival overgrowth,the beneficiary of a functional transplanted kidney about9 years ago, treated with two immunosuppressives, whohas undergone gingivectomy with electrocautery, as a necessaryintervention to improve the oral hygiene and toavoid worsening of malfunctions in the oral cavity.

Analysis of the effects of simulated synergistic LEO environment on solar panels

Science.gov (United States)

Allegri, G.; Corradi, S.; Marchetti, M.; Scaglione, S.

2007-02-01

The effects due to the LEO environment exposure of a solar array primary structure are here presented and discussed in detail. The synergistic damaging components featuring LEO environment are high vacuum, thermal cycling, neutral gas, ultraviolet (UV) radiation and cold plasma. The synergistic effects due to these environmental elements are simulated by "on ground" tests, performed in the Space Environment Simulator (SAS) at the University of Rome "La Sapienza"; numerical simulations are performed by the Space Environment Information System (SPENVIS), developed by the European Space Agency (ESA). A "safe life" design for a solar array primary structure is developed, taking into consideration the combined damaging action of the LEO environment components; therefore results from both numerical and experimental simulations are coupled within the framework of a standard finite element method (FEM) based design. The expected durability of the solar array primary structure, made of laminated sandwich composite, is evaluated assuming that the loads exerted on the structure itself are essentially dependent on thermo-elastic stresses. The optical degradation of surface materials and the stiffness and strength degradation of structural elements are taken into account to assess the global structural durability of the solar array under characteristic operative conditions in LEO environment.

O preço do petróleo como factor global: análise sectorial

OpenAIRE

Martinho, Isabel Rodrigues

2010-01-01

Mestrado em Finanças/ G12; Q40 Nos últimos anos tornou-se bastante popular o investimento em commodities, nomeadamente, em petróleo. Entre as várias possibilidades que existem, uma delas é o investimento em acções de empresas do sector petrolífero. Esta tese emprega um modelo multifactorial para identificar, no período 2000-2009, os principais determinantes da rendibilidade dos sectores de produtores de petróleo e gás; equipamentos, serviços e distribuição de petróleo;...

Efeito de enzimas hidrolíticas no comportamento reológico do óleo de palma cru

OpenAIRE

FREITAS,Suely P.; SILVA,Fernando C.; LAGO,Regina C.A.; COURI,Sonia

1998-01-01

No processamento tradicional de extração de óleo de palma, uma quantidade substancial do produto é perdida na fibra - durante a etapa de prensagem do fruto - e na borra - durante a etapa de clarificação do óleo cru. A viscosidade deste constitui a principal dificuldade de separação do óleo dos demais componentes da mistura. A eficiência de recuperação do óleo é usualmente melhorada por adição de água, no tanque de clarificação. Neste trabalho avaliou-se os efeitos da diluição e do tratamento ...

The dynamics of biofilm overgrowth of Enterococcus faecalis

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E. A. Synetar

2015-08-01

Full Text Available The nature of microorganisms can exist in two physiological forms that allow microbes to preserve livelihoods and continue their life cycle. The first is the population of planktonic forms of microorganisms which live freely in the environment with the developed systems of active and passive mobility, contributing to the rapid spread of a liquid medium. The second forms are those expressing specific mechanisms of adhesion, and able to aggregate on biogenic and abiogenic surfaces. Even in the deep sea vast number of species of bacteria live in their inherent horizons. Thus, the study of biofilms tube life support systems, diagnostic, laparoscopic devices during prolonged catheterization of the urinary system is of great practical, theoretical and biological significance in medicine and biology. For almost 20% of catheter-associated infections antibiotic therapy is uneffective, particularly through the formation of microbial biofilms on the surface of urinary catheters. We characterized the dynamics of biofilm growth of Enterococcus faecalis on fragments ofsilicone catheter. The study was conducted using bacteriological and electron microscopic techniques. Study of the dynamics of biofilm formation was performed using E. faecalis strain 49, which is isolated from the urine of persons who are not the patients of the urological department of resuscitation and intensive therapy. Using scanning electron microscopy we have established dynamics and phase attachment ofE. faecalis bacteria and subsequent overgrowth of silicone catheter surface. Aftercalculations, index of adhesion on the turbulent wall amounted to 0,49 microbial cells. That is, every other cell of the monolayer adhered on the catheter. Area of biofilm growth of E. faecalis after 24 hour incubation was equal to 51.5 μm2, in 48 hours it increased to 231.5 μm2. After 72 hours of incubation we recorded the increase in biofilm growth of E. faecalisto 1922,8 μm2. The results were obtained

Synthesis of Si epitaxial layers from technical silicon by liquid-phase epitaxy method

International Nuclear Information System (INIS)

Ibragimov, Sh.I.; Saidov, A.S.; Sapaev, B.; Horvat, M.A.

2004-01-01

Full text: For today silicon is one of the most suitable materials because it is investigated, cheap and several its parameters are even just as good as those of connections A III B V . Disintegration of the USSR has led to the must difficult position of the industry of silicon instrument manufacture because of all industry of semiconductor silicon manufacture had generally concentrated in Ukraine. The importance of semiconductor silicon is rather great, because of, in opinion of expects, the nearest decade this material will dominate over not only on microelectronics but also in the majority of basic researches. Research of obtain of semiconductor silicon, power electronics and solar conversion, is topical interest of the science. In the work research of technological conditions of obtain and measurement of parameters of epitaxial layers obtained from technical silicon + stannum is resulted. Growth of silicon epitaxial layer with suitable parameters on thickness, cleanliness uniformity and structural perfection depends on the correct choice of condition of the growth and temperature. It is shown that in this case the growth occurring without preliminary clearing of materials (mix materials and substrates) at crystallization of epitaxial layer from technical silicon is accompanied by clearing of silicon film from majority of impurities order-of-magnitude. As starting raw material technical silicon of mark Kr.3 has been taken. By means of X-ray microanalyzer 'Jeol' JSM 5910 LV - Japan the quantitative analysis from the different points has been and from the different sides and from different points has been carried out. After corresponding chemical and mechanical processing the quantitative analysis of layer on chip has been carried out. Results of the quantitative analysis are shown. More effective clearing occurs that of the impurity atoms such as Al, P, Ca, Ti and Fe. The obtained material (epitaxial layer) has the parameters: specific resistance ρ∼0.1-4.0 �

Impact of N-plasma and Ga-irradiation on MoS2 layer in molecular beam epitaxy

KAUST Repository

Mishra, Pawan

2017-01-03

Recent interest in two-dimensional materials has resulted in ultra-thin devices based on the transfer of transition metal dichalcogenides (TMDs) onto other TMDs or III-nitride materials. In this investigation, we realized p-type monolayer (ML) MoS2, and intrinsic GaN/p-type MoS2 heterojunction by the GaN overgrowth on ML-MoS2/c-sapphire using the plasma-assisted molecular beam epitaxy. A systematic nitrogen plasma (N∗2N2*) and gallium (Ga) irradiation studies are employed to understand the individual effect on the doping levels of ML-MoS2, which is evaluated by micro-Raman and high-resolution X-Ray photoelectron spectroscopy (HRXPS) measurements. With both methods, p-type doping was attained and was verified by softening and strengthening of characteristics phonon modes E12gE2g1 and A1gA1g from Raman spectroscopy. With adequate N∗2N2*-irradiation (3 min), respective shift of 1.79 cm−1 for A1gA1g and 1.11 cm−1 for E12gE2g1 are obtained while short term Ga-irradiated (30 s) exhibits the shift of 1.51 cm−1 for A1gA1g and 0.93 cm−1 for E12gE2g1. Moreover, in HRXPS valence band spectra analysis, the position of valence band maximum measured with respect to the Fermi level is determined to evaluate the type of doping levels in ML-MoS2. The observed values of valance band maximum are reduced to 0.5, and 0.2 eV from the intrinsic value of ≈1.0 eV for N∗2N2*- and Ga-irradiated MoS2 layers, which confirms the p-type doping of ML-MoS2. Further p-type doping is verified by Hall effect measurements. Thus, by GaN overgrowth, we attained the building block of intrinsic GaN/p-type MoS2 heterojunction. Through this work, we have provided the platform for the realization of dissimilar heterostructure via monolithic approach.

Reclamation of a molecular beam epitaxy system and conversion for oxide epitaxy

International Nuclear Information System (INIS)

Carver, Alexander G.; Henderson, Walter; Doolittle, W. Alan

2008-01-01

An early 1980s vintage molecular beam epitaxy system, a Varian Gen II system, originally used for HgCdTe epitaxy, was converted into a system capable of growing thin-film complex metal oxides. The nature of some of the alternative oxides requires a thorough cleaning and, in some cases, complete replacement of system components. Details are provided regarding the chemistry of the etchants used, safety requirements for properly handling, and disposal of large quantities of etchants and etch by-products, and components that can be reused versus components that require replacement are given. Following the given procedures, an ultimate base pressure of 2x10 -10 Torr was obtained. Films grown in the system after reclamation contained no evidence of previously present materials down to the detection limit of secondary ion mass spectrometry

ESTUDO TRIBOLÓGICO DE ÓLEOS BIODEGRADÁVEIS DE COCO E DE RÍCINO ATRAVÉS DE ENSAIOS ABRASIVOS

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jaciana silva de santana

2010-11-01

Full Text Available Em substituição aos óleos minerais, os óleos biodegradáveis vêm proporcionando uma grande alternativa ao mercado, uma vez que o mesmo diminui os impactos ambientais. Com a finalidade de avaliar o desempenho do óleo de rícino (refinado e bruto e o óleo de coco comparando-os com os óleos minerais SAE 20W50 SJ e W40, realizaram-se ensaios tribológicos de desgaste na configuração pino-contra-cilindro de aço AISI 52100. As superfícies das amostras metálicas foram confeccionadas por torneamento e lixamento, utilizando-se lixas de diferentes granulometrias, seguidas por limpeza com banho ultrassônico e pesagem antes e após a realização dos ensaios. Os corpos-de-prova foram analisados antes dos ensaios no microscópio óptico. A dureza do aço AISI 52100 foi medida utilizando-se um durômetro Rockwell. O óleo foi caracterizado através de ensaios de densidade e tensão superficial (Souza et. al., 2007. A eficiência da ação do lubrificante foi avaliada através da taxa de desgaste calculada para as amostras utilizando-se a equação de Archard e através da microscopia eletrônica de varredura (MEV. Segundo resultados da taxa de desgaste, os óleos vegetais de rícino e coco obtiveram valores de 88,89 % e 33,33 % menores que para os óleos W40 e SAE 20W50 SJ, respectivamente. Sendo assim, os óleos vegetais possuem propriedades tribológicas equivalentes e até superiores às dos óleos minerais estudados.

Utilização da Energia de Dietas para Frangos de Corte Formuladas com Óleo Ácido de Soja

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Vieira SL

2002-01-01

Full Text Available O produto comercialmente chamado "óleo ácido de soja", resulta da acidificação da borra residual do processo de refino do óleo de soja. Este tem sido muito utilizado na indústria de rações animais, ainda que com vários questinamentos a cerca de sua eficiência, tais como a adulteração com outros ácidos graxos de baixo valor nutricional, nível de peroxidação, presença de impurezas, e valores energéticos não confiáveis. Neste estudo, foi avaliado o desempenho de frangos de corte consumindo dietas contendo óleo de soja ou óleo ácido de soja nos níveis de 4 e 8% ou a mistura das duas fontes em partes iguais de 2 e 4% cada. Essas dietas foram fornecidas para frangos de corte alojados em baterias climatizadas a partir dos 7 dias de idade. As aves que receberam misturas equivalentes de óleo ácido de soja e óleo de soja apresentaram menor peso corporal no final do experimento (aos 42 dias quando comparadas com aquelas que consumiram apenas óleo ou óleo ácido de soja, independentemente do nível adicionado. O nível de inclusão de óleo de soja ou óleo ácido de soja não influenciou o peso final das aves. Foi verificado maior consumo de ração pelos animais que receberam dietas de menor nível de inclusão, o que contribuiu para piorar a conversão alimentar dos mesmos. O óleo ácido de soja demonstrou ser uma fonte energética alternativa de alto potencial econômico para uso em dietas comerciais para frangos de corte, apresentando valor energético de 8.114 kcal EMAn/kg de MS, valor 5% inferior ao determinado para o óleo de soja degomado.

Self-assembled epitaxial NiSi2 nanowires on Si(001) by reactive deposition epitaxy

International Nuclear Information System (INIS)

Chen, S.Y.; Chen, L.J.

2006-01-01

Self-assembled epitaxial NiSi 2 nanowires have been fabricated on Si(001) by reactive deposition epitaxy (RDE). The RDE method promoted nanowire growth since it provides deposited atoms sufficient kinetic energy for movement on the Si surface during the growth of silicide islands. The twin-related interface between NiSi 2 and Si is directly related to the nanowire formation since it breaks the symmetry of the surface and leads to the asymmetric growth. The temperature of RDE was found to greatly influence the formation of nanowires. By RDE at 750 deg. C, a high density of NiSi 2 nanowires was formed with an average aspect ratio of 30

Molecular beam epitaxy a short history

CERN Document Server

Orton, J W

2015-01-01

This volume describes the development of molecular beam epitaxy from its origins in the 1960s through to the present day. It begins with a short historical account of other methods of crystal growth, both bulk and epitaxial, to set the subject in context, emphasising the wide range of semiconductor materials employed. This is followed by an introduction to molecular beams and their use in the Stern-Gerlach experiment and the development of the microwave MASER.

El íleo biliar: una revisión de la literatura médica

Directory of Open Access Journals (Sweden)

C.F. Ploneda-Valencia

2017-07-01

Conclusiones: El objetivo del tratamiento del íleo biliar es liberar la obstrucción, obtenido a través de la enterolitotomía. Esta es la técnica recomendada para el manejo del íleo biliar debido a su morbimortalidad menor, comparada con las otras técnicas.

Alfalfa discovery of the nearby gas-rich dwarf galaxy Leo P. IV. Distance measurement from LBT optical imaging

Energy Technology Data Exchange (ETDEWEB)

McQuinn, Kristen B. W.; Skillman, Evan D.; Berg, Danielle [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street, S.E., University of Minnesota, Minneapolis, MN 55455 (United States); Cannon, John M. [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); Salzer, John J.; Rhode, Katherine L. [Department of Astronomy, Indiana University, 727 East 3rd Street, Bloomington, IN 47405 (United States); Adams, Elizabeth A. K.; Giovanelli, Riccardo; Haynes, Martha P. [Center for Radiophysics and Space Research, Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States); Dolphin, Andrew, E-mail: kmcquinn@astro.umn.edu, E-mail: skillman@astro.umn.edu, E-mail: berg@astro.umn.edu, E-mail: jcannon@macalester.edu, E-mail: rhode@astro.indiana.edu, E-mail: slaz@astro.indiana.edu, E-mail: betsey@astro.cornell.edu, E-mail: riccardo@astro.cornell.edu, E-mail: haynes@astro.cornell.edu [Raytheon Company, 1151 E. Hermans Road, Tucson, AZ 85756 (United States)

2013-12-01

Leo P is a low-luminosity dwarf galaxy discovered through the blind H I Arecibo Legacy Fast ALFA survey. The H I and follow-up optical observations have shown that Leo P is a gas-rich dwarf galaxy with both active star formation and an underlying older population, as well as an extremely low oxygen abundance. Here, we measure the distance to Leo P by applying the tip of the red giant branch (TRGB) distance method to photometry of the resolved stellar population from new Large Binocular Telescope V and I band imaging. We measure a distance modulus of 26.19{sub −0.50}{sup +0.17} mag corresponding to a distance of 1.72{sub −0.40}{sup +0.14} Mpc. Although our photometry reaches 3 mag below the TRGB, the sparseness of the red giant branch yields higher uncertainties on the lower limit of the distance. Leo P is outside the Local Group with a distance and velocity consistent with the local Hubble flow. While located in a very low-density environment, Leo P lies within ∼0.5 Mpc of a loose association of dwarf galaxies which include NGC 3109, Antlia, Sextans A, and Sextans B, and 1.1 Mpc away from its next nearest neighbor, Leo A. Leo P is one of the lowest metallicity star-forming galaxies known in the nearby universe, comparable in metallicity to I Zw 18 and DDO 68, but with stellar characteristics similar to dwarf spheriodals (dSphs) in the Local Volume such as Carina, Sextans, and Leo II. Given its physical properties and isolation, Leo P may provide an evolutionary link between gas-rich dwarf irregular galaxies and dSphs that have fallen into a Local Group environment and been stripped of their gas.

Droplet Epitaxy Image Contrast in Mirror Electron Microscopy

Science.gov (United States)

Kennedy, S. M.; Zheng, C. X.; Jesson, D. E.

2017-01-01

Image simulation methods are applied to interpret mirror electron microscopy (MEM) images obtained from a movie of GaAs droplet epitaxy. Cylindrical symmetry of structures grown by droplet epitaxy is assumed in the simulations which reproduce the main features of the experimental MEM image contrast, demonstrating that droplet epitaxy can be studied in real-time. It is therefore confirmed that an inner ring forms at the droplet contact line and an outer ring (or skirt) occurs outside the droplet periphery. We believe that MEM combined with image simulations will be increasingly used to study the formation and growth of quantum structures.

Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight cell - Update II

Science.gov (United States)

Smithrick, John J.; Hall, Stephen W.

1992-01-01

An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent KOH electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel (IPV) nickel-hydrogen cells has been previously reported. The cycle life of boiler plate cells containing 26 percent potassium hydroxide (KOH) electrolyte was about 40,000 LEO cycles, compared to 3500 cycles for cells containing 31 percent KOH. The cycle regime was a stressful accelerated LEO, which consisted of a 27.5 min charge followed by a 17.5 min discharge (2X normal rate). The depth-of-discharge was 80 percent. Six 48-Ah Hughes recirculation design IPV nickel-hydrogen flight battery cells are being evaluated. Three of the cells contain 26 percent KOH (test cells), and three contain 31 percent KOH (control cells). They are undergoing real time LEO cycle life testing. The cycle regime is a 90-min LEO orbit consisting of a 54-min charge followed by a 36-min discharge. The depth-of-discharge is 80 percent. The cell temperature is maintained at 10 C. The three 31 percent KOH cells failed (cycles 3729, 4165, and 11355). One of the 26 percent KOH cells failed at cycle 15314. The other two 26 percent KOH cells were cycled for over 16,000 cycles during the continuing test.

Key issues of multiple access technique for LEO satellite communication systems

Institute of Scientific and Technical Information of China (English)

温萍萍; 顾学迈

2004-01-01

The large carrier frequency shift caused by the high-speed movement of satellite (Doppler effects) and the propagation delay on the up-down link are very critical issues in an LEO satellite communication system, which affects both the selection and the implementation of a suitable access method. A Doppler based multiple access technique is used here to control the flow and an MPRMA-HS protocol is proposed for the application in LEO satellite communication systems. The extended simulation trials prove that the proposed scheme seems to be a very promising access method.

Integrated Ideas of a Life Warrior ~ An Interview with Leo Fong

Directory of Open Access Journals (Sweden)

Peter Hobart

2012-07-01

Full Text Available Mr. Leo Fong is the architect and founder of a system of martial arts known as Wei Kuen Do (man. Hui Quan Dao—the Way of the Integrated Fist. Leo Fong trained in a variety of Chinese disciplines, including Shaolin, Choy Lay Fut and Tiger Claw, and was a close associate of Bruce Lee. Over the course of his studies, Master Fong combined many of the aspects of Chinese martial arts with principles of western boxing, to produce his own, unique and devastating system of self-defense.

Dislocations limited electronic transport in hydride vapour phase epitaxy grown GaN templates: A word of caution for the epitaxial growers

Energy Technology Data Exchange (ETDEWEB)

Chatterjee, Abhishek, E-mail: cabhishek@rrcat.gov.in; Khamari, Shailesh K.; Kumar, R.; Dixit, V. K.; Oak, S. M.; Sharma, T. K., E-mail: tarun@rrcat.gov.in [Semiconductor Physics and Devices Laboratory, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

2015-01-12

GaN templates grown by hydride vapour phase epitaxy (HVPE) and metal organic vapour phase epitaxy (MOVPE) techniques are compared through electronic transport measurements. Carrier concentration measured by Hall technique is about two orders larger than the values estimated by capacitance voltage method for HVPE templates. It is learnt that there exists a critical thickness of HVPE templates below which the transport properties of epitaxial layers grown on top of them are going to be severely limited by the density of charged dislocations lying at layer-substrate interface. On the contrary MOVPE grown templates are found to be free from such limitations.

Leo satellite-based telecommunication network concepts

Science.gov (United States)

Aiken, John G.; Swan, Peter A.; Leopold, Ray J.

1991-01-01

Design considerations are discussed for Low Earth Orbit (LEO) satellite based telecommunications networks. The satellites are assumed to be connected to each other via intersatellite links. They are connected to the end user either directly or through gateways to other networks. Frequency reuse, circuit switching, packet switching, call handoff, and routing for these systems are discussed by analogy with terrestrial cellular (mobile radio) telecommunication systems.

The Bacterial Overgrowth Syndrome is Uncommon in Pernicious Anaemia: Results of a Follow-up Study

OpenAIRE

Stockbrügger, R. W.; Armbrecht, U.; Rode, J. W.; Teall, A. J.; Oberholzer, V. G.; Croker, J. R.; Cotton, P. B.

2011-01-01

It is still uncertain whether upper gastrointestinal bacterial overgrowth in patients with permanent achlorhydria causes malassimilation in more than just the occasional case. In an attempt to clarify this, 19 patients with pernicious anaemia who had undergone a thorough investigation 6.6 y (mean) previously, were reinvestigated with clinical history, upper GI endoscopy including multiple duodenal biopsies, microbial cultures of gastric juice and duodenal mucosa, a xylose absorption test, and...

OPTEL-μ LEO to ground laser communications terminal: flight design and status of the EQM development project

Science.gov (United States)

Baister, G.; Greger, R.; Bacher, M.; Stumpf, M.; Francou, L.; Buchheim, K.

2017-09-01

The OPTEL-μ terminal is designed to transmit data generated on-board LEO satellites to an optical ground station at a data rate of 2 Gbps. This would allow operators of LEO satellites to downlink the large amounts of data being generated by their payload to ground. To make this technology attractive to LEO satellite user community the design of the OPTEL-μ has minimal impact to the spacecraft resources.

A high resolution cross section transmission electron microscopy study of epitaxial rare earth fluoride/GaAs(111) interfaces prepared by molecular beam epitaxy

International Nuclear Information System (INIS)

Chien, C.J.; Bravman, J.C.

1990-01-01

The authors report the HRXTEM study of epitaxial rare earth fluoride/GaAs(111) interfaces. Such interfaces are of interest because they are the starting point for growth of buried epitaxial rare earth/rare earth fluoride sandwich structures which exhibit interesting and non bulk-like magnetic properties. Also, the optical transitions in ultrathin epitaxial NdF 3 films may be influenced by strain and defects in the NdF 3 film and the nature of the interface to GaAs. The authors find that the rare earth fluoride/GaAs interfaces are semi-coherent but chemically abrupt with the transition taking place within 3 Angstrom. However, the interface is physically rough and multiple monolayer steps in the GaAs surface tend to tilt boundaries in the fluoride. The origin of these steps is believed to be thermal etching of the GaAs during the heat- cleaning stage prior to epitaxy. The surface of the fluoride film is much smoother than the initial GaAs surface indicating planarization during epitaxy

LEO P: HOW MANY METALS CAN A VERY LOW MASS, ISOLATED GALAXY RETAIN?

Energy Technology Data Exchange (ETDEWEB)

McQuinn, Kristen B. W.; Skillman, Evan D. [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street, S.E., University of Minnesota, Minneapolis, MN 55455 (United States); Dolphin, Andrew [Raytheon Company, 1151 E. Hermans Road, Tucson, AZ 85756 (United States); Cannon, John M. [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); Salzer, John J.; Rhode, Katherine L. [Department of Astronomy, Indiana University, 727 East 3rd Street, Bloomington, IN 47405 (United States); Adams, Elizabeth A. K. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Berg, Danielle [Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin Milwaukee, 1900 East Kenwood Boulevard, Milwaukee, WI 53211 (United States); Giovanelli, Riccardo; Haynes, Martha P., E-mail: kmcquinn@astro.as.utexas.edu [Center for Radiophysics and Space Research, Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States)

2015-12-20

Leo P is a gas-rich dwarf galaxy with an extremely low gas-phase oxygen abundance (3% solar). The isolated nature of Leo P enables a quantitative measurement of metals lost solely due to star formation feedback. We present an inventory of the oxygen atoms in Leo P based on the gas-phase oxygen abundance measurement, the star formation history (SFH), and the chemical enrichment evolution derived from resolved stellar populations. The SFH also provides the total amount of oxygen produced. Overall, Leo P has retained 5% of its oxygen; 25% of the retained oxygen is in the stars while 75% is in the gas phase. This is considerably lower than the 20%–25% calculated for massive galaxies, supporting the trend for less efficient metal retention for lower-mass galaxies. The retention fraction is higher than that calculated for other alpha elements (Mg, Si, Ca) in dSph Milky Way satellites of similar stellar mass and metallicity. Accounting only for the oxygen retained in stars, our results are consistent with those derived for the alpha elements in dSph galaxies. Thus, under the assumption that the dSph galaxies lost the bulk of their gas mass through an environmental process such as tidal stripping, the estimates of retained metal fractions represent underestimates by roughly a factor of four. Because of its isolation, Leo P provides an important datum for the fraction of metals lost as a function of galaxy mass due to star formation.

Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight battery cells

Science.gov (United States)

Smithrick, John J.; Hall, Stephen W.

1990-01-01

A breakthrough in the low-earth-orbit (LEO) cycle life of individual pressure vessel (IPV) nickel hydrogen battery cells is reported. The cycle life of boiler plate cells containing 26 percent potassium hydroxide (KOH) electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH. The effect of KOH concentration on cycle life was studied. The cycle regime was a stressful accelerated LEO, which consisted of a 27.5 min charge followed by a 17.5 min charge (2 x normal rate). The depth of discharge (DOD) was 80 percent. The cell temperature was maintained at 23 C. The next step is to validate these results using flight hardware and real time LEO test. NASA Lewis has a contract with the Naval Weapons Support Center (NWSC), Crane, Indiana to validate the boiler plate test results. Six 48 A-hr Hughes recirculation design IPV nickel-hydrogen flight battery cells are being evaluated. Three of the cells contain 26 percent KOH (test cells) and three contain 31 percent KOH (control cells). They are undergoing real time LEO cycle life testing. The cycle regime is a 90-min LEO orbit consisting of a 54-min charge followed by a 36-min discharge. The depth-of-discharge is 80 percent. The cell temperature is maintained at 10 C. The cells were cycled for over 8000 cycles in the continuing test. There were no failures for the cells containing 26 percent KOH. There were two failures, however, for the cells containing 31 percent KOH.

Challenging Christianity: Leo Tolstoy and Religious Education

Science.gov (United States)

Moulin, Dan

2009-01-01

The religious thought of Russian novelist Leo Tolstoy is a well documented but often overlooked example of unorthodox Christianity. This paper uses the example of Tolstoy's religious thinking to question the integrity of the current representation of Christianity in UK schools. It also uses Tolstoy's criticism of orthodox Christianity to suggest a…

Deep neutral hydrogen observations of Leo T with the Westerbork Synthesis Radio Telescope

Science.gov (United States)

Adams, Elizabeth A. K.; Oosterloo, Tom A.

2018-04-01

Leo T is the lowest mass gas-rich galaxy currently known and studies of its gas content help us understand how such marginal galaxies survive and form stars. We present deep neutral hydrogen (H I) observations from the Westerbork Synthesis Radio Telescope in order to understand its H I distribution and potential for star formation. We find a larger H I line flux than the previously accepted value, resulting in a 50% larger H I mass of 4.1 × 105 M⊙. The additional H I flux is from low surface brightness emission that was previously missed; with careful masking this emission can be recovered even in shallower data. We perform a Gaussian spectral decomposition to find a cool neutral medium component (CNM) with a mass of 3.7 × 104 M⊙, or almost 10% of the total H I mass. Leo T has no H I emission extending from the main H I body, but there is evidence of interaction with the Milky Way circumgalactic medium in both a potential truncation of the H I body and the offset of the peak H I distribution from the optical center. The CNM component of Leo T is large when compared to other dwarf galaxies, even though Leo T is not currently forming stars and has a lower star formation efficiency than other gas-rich dwarf galaxies. However, the H I column density associated with the CNM component in Leo T is low. One possible explanation is the large CNM component is not related to star formation potential but rather a recent, transient phenomenon related to the interaction of Leo T with the Milky Way circumgalactic medium. The reduced datacube (FITS file) is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/612/A26

Poly-epiphyseal overgrowth: description of a previously unreported skeletal dysplasia

Energy Technology Data Exchange (ETDEWEB)

Pazzaglia, Ugo E.; Bonaspetti, Giovanni [University of Brescia, Orthopaedic Clinic, Brescia (Italy); Beluffi, Giampiero [Fondazione IRCCS Policlinico San Matteo, Department of Paediatric Radiology, Pavia (Italy); Marchi, Antonietta; Bozzola, Mauro; Savasta, Salvatore [Fondazione IRCCS Policlinico San Matteo, Paediatric Clinic, University of Pavia, Pavia (Italy)

2007-10-15

A skeletal dysplasia with previously unreported features is presented. Its evolution was characterized by growth abnormalities of bones without involvement of other organs. Advanced bone age, increased stature and irregular epiphyseal ossification with stippling of the main long bones were documented. Physeal overgrowth was massive in the left proximal humerus and femur. Furthermore, the hip joint appeared fused with an abundant mass of pathological calcific tissue extending from the femur to the ilium. Pathological epiphyses were characterized by anarchic cartilaginous proliferation with multiple ossification centres, while lamellar bone apposition and remodelling were normal. The observed bone changes were different from those in any previously reported syndrome, metabolic defect or bone dysplasia. However, they clearly indicated a defect of endochondral ossification with some resemblance to phenotypes observed in dysplasia epiphysealis hemimelica. (orig.)

Poly-epiphyseal overgrowth: description of a previously unreported skeletal dysplasia

International Nuclear Information System (INIS)

Pazzaglia, Ugo E.; Bonaspetti, Giovanni; Beluffi, Giampiero; Marchi, Antonietta; Bozzola, Mauro; Savasta, Salvatore

2007-01-01

A skeletal dysplasia with previously unreported features is presented. Its evolution was characterized by growth abnormalities of bones without involvement of other organs. Advanced bone age, increased stature and irregular epiphyseal ossification with stippling of the main long bones were documented. Physeal overgrowth was massive in the left proximal humerus and femur. Furthermore, the hip joint appeared fused with an abundant mass of pathological calcific tissue extending from the femur to the ilium. Pathological epiphyses were characterized by anarchic cartilaginous proliferation with multiple ossification centres, while lamellar bone apposition and remodelling were normal. The observed bone changes were different from those in any previously reported syndrome, metabolic defect or bone dysplasia. However, they clearly indicated a defect of endochondral ossification with some resemblance to phenotypes observed in dysplasia epiphysealis hemimelica. (orig.)

Moore'i seadus ja meie tulevik / Leo Võhandu

Index Scriptorium Estoniae

Võhandu, Leo, 1929-

2006-01-01

Kiibifirma Intel üks asutajaid Gordon Moore väitis 1965. aastal, et transistorite arv kiibil topeldub iga kahe aastaga ehk loomulik areng ei ole lineaarne, vaid eksponentsiaalne (astmeline). TTÜ emeriitprofessor Moore'i seaduse mõjust ühiskonna arengule. Vt. samas: Leo Võhandu

THE LEO IV DWARF SPHEROIDAL GALAXY: COLOR-MAGNITUDE DIAGRAM AND PULSATING STARS

International Nuclear Information System (INIS)

Moretti, Maria Ida; Dall'Ora, Massimo; Ripepi, Vincenzo

2009-01-01

We present the first V, B - V color-magnitude diagram of the Leo IV dwarf spheroidal galaxy, a faint Milky Way satellite recently discovered by the Sloan Digital Sky Survey. We have obtained B, V time-series photometry reaching about half a magnitude below the Leo IV turnoff, which we detect at V = 24.7 mag, and have performed the first study of the variable star population. We have identified three RR Lyrae stars (all fundamental-mode pulsators, RRab) and one SX Phoenicis variable in the galaxy. In the period-amplitude diagram the Leo IV RR Lyrae stars are located close to the loci of Oosterhoff type I systems and the evolved fundamental-mode RR Lyrae stars in the Galactic globular cluster M3. However, their mean pulsation period, (Pab) = 0.655 days, would suggest an Oosterhoff type II classification for this galaxy. The RR Lyrae stars trace very well the galaxy's horizontal branch, setting its average magnitude at (V RR ) = 21.48 ± 0.03 mag (standard deviation of the mean). This leads to a distance modulus of μ 0 = 20.94 ± 0.07 mag, corresponding to a distance of 154 ± 5 kpc, by adopting for the Leo IV dSph a reddening E(B - V) = 0.04 ± 0.01 mag and a metallicity of [Fe/H] = -2.31 ± 0.10.

High sensitive quasi freestanding epitaxial graphene gas sensor on 6H-SiC

NARCIS (Netherlands)

Iezhokin, I.; Offermans, P.; Brongersma, S.H.; Giesbers, A.J.M.; Flipse, C.F.J.

2013-01-01

We have measured the electrical response to NO2, N2, NH3, and CO for epitaxial graphene and quasi freestanding epitaxial graphene on 6H-SiC substrates. Quasi freestanding epitaxial graphene shows a 6 fold increase in NO2 sensitivity compared to epitaxial graphene. Both samples show a sensitivity

Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight cells-update 2

Science.gov (United States)

Smithrick, John J.; Hall, Stephen W.

1991-01-01

An update of validation test results confirming the breakthrough in low earth orbit (LEO) cycle life of nickel-hydrogen cells containing 26 percent KOH electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel (IPV nickel-hydrogen cells has been previously reported. The cycle life of boiler plate cells containing 26 percent potassium hydroxide (KOH) electrolyte was about 40 000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH. This test was conducted at Hughes Aircraft Company under a NASA Lewis contract. The purpose was to investigate the effect of KOH concentration on cycle life. The cycle regime was a stressful accelerated LEO, which consisted of a 27.5 min charge followed by a 17.5 min discharge (2x normal rate). The depth of discharge (DOD) was 80 percent. The cell temperature was maintained at 23 C. The boiler plate test results are in the process of being validated using flight hardware and real time LEO test at the Naval Weapons Support Center (NWSC), Crane, Indiana under a NASA Lewis Contract. Six 48 Ah Hughes recirculation design IPV nickel-hydrogen flight battery cells are being evaluated. Three of the cells contain 26 percent KOH (test cells), and three contain 31 percent KOH (control cells). They are undergoing real time LEO cycle life testing. The cycle regime is a 90-min LEO orbit consisting of a 54-min charge followed by a 36-min discharge. The depth-of-discharge is 80 percent. The cell temperature is maintained at 10 C. The three 31 percent KOH cells failed (cycles 3729, 4165, and 11355). One of the 26 percent KOH cells failed at cycle 15314. The other two 26 percent KOH cells were cycled for over 16600 cycles during the continuing test.

Small Intestinal Bacterial Overgrowth: A Case-Based Review

Directory of Open Access Journals (Sweden)

Kristen H. Reynolds

2015-11-01

Full Text Available Small intestinal bacterial overgrowth (SIBO is a condition of increased microbial load in the small intestine. The microbes feed on dietary carbohydrates and starches via fermentation, leading to gas production, inflammation and damage to the lining of the small intestine. Clinical presentation is varied, including abdominal pain, bloating, malabsorption and systemic symptoms. SIBO is associated with many challenging and chronic conditions such as fibromyalgia, chronic fatigue and chronic pain syndromes, and has been shown to be a causative factor in two out of three cases of irritable bowel syndrome. Symptoms improve with antimicrobial treatment, but recurrence is common. Many providers may not be aware of SIBO. This narrative review highlights a clinical case and the most recent literature regarding SIBO, including history, clinical presentation, prevalence, pathophysiology, diagnostic workup, treatment and prevention. Integrative medicine approaches, including diet, supplements and manual therapies, are also reviewed. SIBO can be a challenging condition and requires an integrative, patient-centered approach. Further studies are needed to guide clinicians in the workup and treatment of SIBO.

Junction Transport in Epitaxial Film Silicon Heterojunction Solar Cells: Preprint

Energy Technology Data Exchange (ETDEWEB)

Young, D. L.; Li, J. V.; Teplin, C. W.; Stradins, P.; Branz, H. M.

2011-07-01

We report our progress toward low-temperature HWCVD epitaxial film silicon solar cells on inexpensive seed layers, with a focus on the junction transport physics exhibited by our devices. Heterojunctions of i/p hydrogenated amorphous Si (a-Si) on our n-type epitaxial crystal Si on n++ Si wafers show space-charge-region recombination, tunneling or diffusive transport depending on both epitaxial Si quality and the applied forward voltage.

Avaliação da atividade larvicida do óleo essencial do Zingiber officinale Roscoe (gengibre) frente ao mosquito Aedes aegypti

OpenAIRE

GOMES, P.R.B.; SILVA, A.L.S.; PINHEIRO, H.A.; CARVALHO, L.L.; LIMA, H.S.; SILVA, E.F.; SILVA, R.P.; LOUZEIRO, C.H.; OLIVEIRA, M.B.; FILHO, V.E.M.

2016-01-01

RESUMO Este trabalho analisa o efeito larvicida do óleo Zingiber officinale Roscoe contra larvas em terceiro estágio do mosquito Aedes aegypti. Extraiu-se quantitativamente o óleo essencial por hidrodestilação e calculou-se a CL50 do óleo, a partir dos métodos de Reed-Muench e Pizzi, respectivamente. O óleo essencial obteve CL50 de 76,07 (±2,24) μg mL-1 e rendimento de 0,52% m/v. Os resultados indicam que o óleo essencial avaliado é composto por substâncias que propiciam efeito larvicida cont...

Performances of Saft Lithium-Ion Cells in LEO Cycling

Directory of Open Access Journals (Sweden)

Prevot D.

2017-01-01

The article will thus present the whole LEO cycling results available for the two cells, and will provide afterwards the correlation status of Saft Li-ion Model (SLIM with all the experimental data acquired.

Lattice-Symmetry-Driven Epitaxy of Hierarchical GaN Nanotripods

KAUST Repository

Wang, Ping

2017-01-18

Lattice-symmetry-driven epitaxy of hierarchical GaN nanotripods is demonstrated. The nanotripods emerge on the top of hexagonal GaN nanowires, which are selectively grown on pillar-patterned GaN templates using molecular beam epitaxy. High-resolution transmission electron microscopy confirms that two kinds of lattice-symmetry, wurtzite (wz) and zinc-blende (zb), coexist in the GaN nanotripods. Periodical transformation between wz and zb drives the epitaxy of the hierarchical nanotripods with N-polarity. The zb-GaN is formed by the poor diffusion of adatoms, and it can be suppressed by improving the ability of the Ga adatoms to migrate as the growth temperature increased. This controllable epitaxy of hierarchical GaN nanotripods allows quantum dots to be located at the phase junctions of the nanotripods and nanowires, suggesting a new recipe for multichannel quantum devices.

Utilização de óleos vegetais como bases lubrificantes

OpenAIRE

Matos, Paulo Roberto Rodrigues de

2011-01-01

A demanda dos óleos lubrificantes é cada vez maior na crescente economia brasileira. A utilização de bases vegetais em substituição às minerais poderá trazer benefícios socioeconômicos e ambientais para o país. O objetivo deste trabalho foi verificar a capacidade lubrificante de óleos vegetais e adequá-los em função do seu uso potencial como lubrificante, tendo em vista a variedade de aplicações possíveis. Espera-se com isso obter alguns lubrificantes de base vegetal específicos para aplicaçõ...

Leo Sgouros – Tyrant and Patriot. The Ruler of the Northeastern Peloponnese in the Early 13th Century

Directory of Open Access Journals (Sweden)

Viktor N. Chkhaidze

2017-11-01

Full Text Available Leo Sgouros is one of the Byzantine magnates who ruled in the northeastern Peloponnese in the late 12th – early 13th centuries. The paper discusses the separatist activity of the Leo Sgouros which allowed him in a short time to create ephemeral ‘state’ in the South of Thessaly, Boeotia, Attica, Corinth and the Argolid. In order to give legitimacy to his authority Leo Sgouros married the daughter of the deposed Emperor Alexios III. But his way from separatism to Imperial idea was interrupted by the clash with the knights of the Latin Empire who have predetermined his defeat. Among the reasons for the defeat we can name the enmity with the clergy and nonpossibility of joining with other governors in fighting the crusaders. According to later legend, Leo Sgouros died, throwing himself with his horse from the cliff of the Acrocorinth fortress, besieged by the crusaders. According to another version, Leo Sgouros died under the walls of his native city Nauplius. The study examined the seal of the Leo Sgouros with a rare title of sebastohypertatos (higher sebastos, and similar seal which was reused by John Branas. Data analysis suggests that such a contradictory personality as Leo Sgouros’ may be characterized not only as an ambitious tyrant and the defender of Byzantine Hellenism. The Annex contains information about the seven of Sgouros names that have become known in recent years by virtue of the monuments of sphragistics.

Small intestinal bacterial overgrowth in nonalcoholic steatohepatitis: association with toll-like receptor 4 expression and plasma levels of interleukin 8.

LENUS (Irish Health Repository)

Shanab, Ahmed Abu

2011-05-01

Experimental and clinical studies suggest an association between small intestinal bacterial overgrowth (SIBO) and nonalcoholic steatohepatitis (NASH). Liver injury and fibrosis could be related to exposure to bacterial products of intestinal origin and, most notably, endotoxin, including lipopolysaccharide (LPS).

Atomic layer epitaxy of ZnO for applications in molecular beam epitaxy growth of GaN and InGaN

International Nuclear Information System (INIS)

Godlewski, M.; Szczerbakow, A.; Ivanov, V. Yu.; Barski, A.; Goldys, E.M.

2000-01-01

We report the successful atomic layer epitaxy growth of thin ZnO films and their use for GaN and InGaN epitaxy. The properties of ZnO epilayers, obtained by four different procedures, are analysed, as well as of GaN and InGaN films grown on ZnO-coated Si and GaAs by MBE. (author)

Epitaxial growth and characterization of CuGa2O4 films by laser molecular beam epitaxy

OpenAIRE

Hongling Wei; Zhengwei Chen; Zhenping Wu; Wei Cui; Yuanqi Huang; Weihua Tang

2017-01-01

Ga2O3 with a wide bandgap of ∼ 4.9 eV can crystalize in five crystalline phases. Among those phases, the most stable monoclinic β-Ga2O3 has been studied most, however, it is hard to find materials lattice matching with β-Ga2O3 to grown epitaxial thin films for optoelectronic applications. In this work, CuGa2O4 bulk were prepared by solid state reaction as target, and the films were deposited on sapphire substrates by laser molecular beam epitaxy (L-MBE) at different substrate temperatures. Th...

Linhaça marrom e dourada: propriedades químicas e funcionais das sementes e dos óleos prensados a frio

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Ana Karina Mauro Barroso

2014-01-01

Full Text Available O objetivo do estudo foi comparar a composição química e a capacidade antioxidante das sementes e dos óleos de linhaça marrom e dourada, e avaliar a estabilidade oxidativa dos óleos. Nas sementes, foram determinados: composição centesimal, capacidade antioxidante total e compostos fenólicos totais. Nos óleos, foram determinados: índice de acidez e peróxido, matéria insaponificável, composição em ácidos graxos, tocoferóis, capacidade antioxidante, compostos fenólicos totais e estabilidade oxidativa em quatro condições de estocagem por até um ano. Não houve diferenças significativas entre os tipos de sementes quanto às variáveis investigadas, e ainda entre os óleos quanto ao rendimento da prensagem, composição em ácidos graxos insaturados, índice de acidez, teores de insaponificáveis e compostos fenólicos totais. Apesar do declínio da estabilidade oxidativa de ambos os óleos durante o armazenamento, o óleo de linhaça marrom e os óleos estocados sob refrigeração apresentaram-se mais estáveis. O índice de peróxido foi maior no óleo de linhaça dourada. O teor de tocoferol total e capacidade antioxidante total foram maiores no óleo de linhaça marrom. Contudo, observou-se uma igualdade entre as sementes de ambas as variedades de linhaça e uma superioridade do óleo de linhaça marrom.

Bacterial overgrowth and methane production in children with encopresis.

Science.gov (United States)

Leiby, Alycia; Mehta, Devendra; Gopalareddy, Vani; Jackson-Walker, Susan; Horvath, Karoly

2010-05-01

To assess the prevalence of small intestinal bacterial overgrowth (SIBO) and methane production in children with encopresis. Radiographic fecal impaction (FI) scores were assessed in children with secondary, retentive encopresis and compared with the breath test results. Breath tests with hypoosmotic lactulose solution were performed in both the study patients (n = 50) and gastrointestinal control subjects (n = 39) groups. The FI scores were significantly higher in the patients with encopresis who were methane producers (P encopresis and 9 of 39 (23%) of control subjects (P = .06). Methane was produced in 56% of the patients with encopresis versus 23.1% of the control subjects in the gastrointestinal group (P encopresis had a higher prevalence of SIBO, elevated basal methane levels, and higher methane production. Methane production was associated with more severe colonic impaction. Further study is needed to determine whether methane production is a primary or secondary factor in the pathogenesis of SIBO and encopresis.

Caracterização físico-química de misturas de óleos vegetais para fins alimentares.

OpenAIRE

ALMEIDA, K. M. de; MEDEIROS, E. P. de; GOMES, J. P.; SOUSA, E. P. de; SANTOS, J. W. dos

2014-01-01

Objetivou-se, com este trabalho, a elaboração e caracterização de misturas especiais de óleos vegetais para fins alimentícios, com base nos óleos de amendoim, gergelim, maracujá e soja. Os óleos de amendoim e gergelim foram extraídos de sementes das cultivares BRS-Havana e BRS-Seda, respectivamente, cedidas pela Embrapa Algodão enquanto o óleo de maracujá foi adquirido no comércio de São Paulo e o de soja no de Campina Grande. As misturas foram elaboradas com base em uma matriz de planejament...

TOXICIDADE DE ÓLEOS ESSENCIAIS PARA O CONTROLE DE Tetranychus urticae KOCH, 1836 (ACARI: TETRANYCHIDAE

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Camila Santos Teixeira

2017-04-01

Full Text Available O ácaro rajado é considerado uma importante praga agrícola, causando danos em diferentes cultivos. O controle à base de acaricidas químicos pode vir a causar problemas ambientais e à saúde do homem. Desta forma o uso de óleos essenciais obtidos de produtos botânicos é uma alternativa no controle de pragas por apresentar baixo efeito residual, sendo objetivo deste trabalho avaliar a mortalidade e o efeito na fertilidade de fêmeas adultas de Tetranychus urticae submetidas a tratamentos com óleos essenciais de laranja doce e limoneno, fornecidos pela empresa Ferquima Indústria e Comércio LTDA., e pela empresa Pack Indústria e Comércio de Produtos Agropecuários LTDA., respectivamente. Para avaliar a ação fumigante do óleo essencial sobre os ácaros foram realizados testes submetendo fêmeas adultas de T. urticae à dose pura do óleo essencial utilizando as dosagens de 5, 15 e 25 µL em câmaras de fumigação. Após o período de exposição ao óleo foi contabilizado o número de ácaros mortos e a quantidade de ovos depositados. Os resultados não foram significativos para mortalidade e para fertilidade de fêmeas adultas de T. urticae.

Avaliação da atividade larvicida do óleo essencial do Zingiber officinale Roscoe (gengibre frente ao mosquito Aedes aegypti

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P.R.B. GOMES

Full Text Available RESUMO Este trabalho analisa o efeito larvicida do óleo Zingiber officinale Roscoe contra larvas em terceiro estágio do mosquito Aedes aegypti. Extraiu-se quantitativamente o óleo essencial por hidrodestilação e calculou-se a CL50 do óleo, a partir dos métodos de Reed-Muench e Pizzi, respectivamente. O óleo essencial obteve CL50 de 76,07 (±2,24 μg mL-1 e rendimento de 0,52% m/v. Os resultados indicam que o óleo essencial avaliado é composto por substâncias que propiciam efeito larvicida contra Aedes aegypti.

Phylogeographic Patterns in Africa and High Resolution Delineation of Genetic Clades in the Lion (Panthera leo)

NARCIS (Netherlands)

Bertola, L.D.; Jongbloed, H.; van der Gaag, K.J.; de Knijff, P.; Yamaguchi, N.; Hooghiemstra, H.; Bauer, H.; Henschel, P.; White, P.A.; Driscoll, C.A.; Tende, T.; Ottosson, U.; Saidu, Y.; Vrieling, K.; de Iongh, H.H.

2016-01-01

Comparative phylogeography of African savannah mammals shows a congruent pattern in which populations in West/Central Africa are distinct from populations in East/Southern Africa. However, for the lion, all African populations are currently classified as a single subspecies (Panthera leo leo), while

Biodiesel produzido com óleo de frango - DOI: 10.4025/actascitechnol.v30i1.3203

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Luis Fernando Souza Gomes

2008-05-01

Full Text Available O Brasil ocupa local de destaque no desenvolvimento e uso de fontes renováveis de energia, por causa da sua grande extensão territorial, clima e várias alternativas. Uma destas é a produção de biodiesel, o qual pode substituir o óleo diesel, diminuindo os impactos ao meio ambiente. Na cadeia produtiva de carne de frango, é gerado um resíduo, óleo de frango, com potencial para produção de biodiesel. Neste trabalho, foram determinadas características físico-químicas que podem influenciar nas reações de transesterificação do óleo de frango. Foi levantado o potencial de produção de óleo de frango nas cooperativas da região oeste do Estado do Paraná e rendimento em biodiesel.

Abstracts of 4. International Workshop on Molecular Beam Epitaxy and Vapour Phase Epitaxy Growth Physics and Technology

International Nuclear Information System (INIS)

2001-01-01

4. International Workshop on Molecular Beam Epitaxy and Vapour Phase Epitaxy Growth Physics and Technology is the periodically held forum for discussion the problems connected with manufacturing of different nanostructures (thin films, quantum wells, quantum dots) needed in microelectronics. Preparation of such materials with desirable optical, electrical and magnetic properties being determined by their chemical composition and crystal structure has been discussed in detail during the workshop sessions. Optimization of crystal growth methods such as VPE and MBE from the view point of obtained material properties has also been extensively discussed

Self-Organized Ni Nanocrystal Embedded in BaTiO3 Epitaxial Film

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Ge FF

2010-01-01

Full Text Available Abstract Ni nanocrystals (NCs were embedded in BaTiO3 epitaxial films using the laser molecular beam epitaxy. The processes involving the self-organization of Ni NCs and the epitaxial growth of BaTiO3 were discussed. With the in situ monitoring of reflection high-energy electron diffraction, the nanocomposite films were engineered controllably by the fine alternation of the self-organization of Ni NCs and the epitaxial growth of BaTiO3. The transmission electron microscopy and the X-ray diffraction characterization confirmed that the composite film consists of the Ni NCs layers alternating with the (001/(100-oriented epitaxial BaTiO3 separation layers.

Photovoltaic X-ray detectors based on epitaxial GaAs structures

Energy Technology Data Exchange (ETDEWEB)

Achmadullin, R.A. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Artemov, V.V. [Shubnikov Institute of Crystallography, Russian Academy of Sciences, 59 Leninski pr., Moscow B-333, 117333 (Russian Federation); Dvoryankin, V.F. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation)]. E-mail: vfd217@ire216.msk.su; Dvoryankina, G.G. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Dikaev, Yu.M. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Ermakov, M.G. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Ermakova, O.N. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Chmil, V.B. [Scientific State Center, High Energy Physics Institute, Protvino, Moscow region (Russian Federation); Holodenko, A.G. [Scientific State Center, High Energy Physics Institute, Protvino, Moscow region (Russian Federation); Kudryashov, A.A.; Krikunov, A.I.; Petrov, A.G.; Telegin, A.A. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Vorobiev, A.P. [Scientific State Center, High Energy Physics Institute, Protvino, Moscow region (Russian Federation)

2005-12-01

A new type of the photovoltaic X-ray detector based on epitaxial p{sup +}-n-n'-n{sup +} GaAs structures which provides a high efficiency of charge collection in the non-bias operation mode at room temperature is proposed. The GaAs epitaxial structures were grown by vapor-phase epitaxy on heavily doped n{sup +}-GaAs(1 0 0) substrates. The absorption efficiency of GaAs X-ray detector is discussed. I-V and C-V characteristics of the photovoltaic X-ray detectors are analyzed. The built-in electric field profiles in the depletion region of epitaxial structures are measured by the EBIC method. Charge collection efficiency to {alpha}-particles and {gamma}-radiation are measured. The application of X-ray detectors is discussed.

Epitaxial properties of ZnO thin films on SrTiO3 substrates grown by laser molecular beam epitaxy

International Nuclear Information System (INIS)

Wei, X. H.; Li, Y. R.; Zhu, J.; Huang, W.; Zhang, Y.; Luo, W. B.; Ji, H.

2007-01-01

Epitaxial ZnO thin films with different orientations have been grown by laser molecular beam epitaxy on (001)- (011)-, and (111)-orientated SrTiO 3 single-crystal substrates. The growth behavior was in situ monitored by reflection high-energy electron diffraction, and the epitaxial orientation relations were reconfirmed by ex situ x-ray diffraction measurements. In the case of ZnO on SrTiO 3 (001), four orthogonal domains coexisted in the ZnO epilayer, i.e., ZnO(110) parallel SrTiO 3 (001) and ZnO[-111] parallel SrTiO 3 . For (011)- and (111)-orientated substrates, single-domain epitaxy with c axial orientation was observed, in which the in-plane relationship was ZnO[110] parallel SrTiO 3 [110] irrespective of the substrate orientations. Additionally, the crystalline quality of ZnO on SrTiO 3 (111) was better than that of ZnO on SrTiO 3 (011) because of the same symmetry between the (111) substrates and (001) films. The obtained results can be attributed to the difference of the in-plane crystallographic symmetry. Furthermore, those alignments can be explained by the interface stress between the substrates and the films

Sizing of "Mother Ship and Catcher" Concepts for LEO Small Debris Capture

Science.gov (United States)

Bacon, John B.

2009-01-01

Most Low Earth Orbit (LEO) debris lies in a limited number of inclination "bands" associated with launch latitudes, or with specific useful orbit inclinations (such as polar orbits). Such narrow inclination bands generally have a uniform spread over all possible Right Ascensions of Ascending Node (RAANs), creating a different orbit plane for nearly every piece of debris. This complicates concept of rendezvous and capture for debris removal. However, a low-orbiting satellite will always phase in RAAN faster than debris objects in higher orbits at the same inclination, potentially solving the problem. Such a base can serve as a single space-based launch facility (a "mother ship") that can tend and then send tiny individual catcher devices for each debris object, as the facility drifts into the same RAAN as the higher object. This presentation will highlight characteristic system requirements of such an architecture, including structural and navigation requirements, power, mass and dV budgets for both the mother ship and the mass-produced common catcher devices that would clean out selected inclination bands. The altitude and inclination regime over which a band is to be cleared, the size distribution of the debris, and the inclusion of additional mission priorities all affect the sizing of the system. It is demonstrated that major LEO hazardous debris reductions can be realized in each band with a single LEO launch of a single mother ship, with simple attached catchers of total mass less than typical commercial LEO launch capability.

PROSPECÇÃO TECNOLÓGICA DE ÓLEO ESSENCIAL DE AROEIRA-DA-PRAIA (Schinus terebinthifolius Raddi.)

OpenAIRE

Mendonça, Valéria Melo; Instituto Federal de Sergipe (IFS) Departamento: Curso Superior Tecnólogo em Agroecologia; Silva-Mann, Renata; Universidade Federal de Sergipe Departamento de Engenharia Agronômica; Rabbani, Allívia Rouse Carregosa; Universidade Federal de Sergipe (UFS) Departamento: Departamento de Engenharia Agronômica

2014-01-01

A aroeira-da-praia (Schinusterebinthifolius Raddi.) é uma espécie brasileira com grande importânciano cenário mundial por diversas características de interesse, dentre elas, oóleo essencial por seu valor fitoterápico. Com o intuito de verificarinformações sobre o uso do óleo essencial desta planta foi realizada umaprospecção em bancos de dados de pesquisa científica, tecnológica e de patentes.Existem muitos trabalhos acadêmicos sobre a aroeira-da-praia, mas poucos sobreóleo essência e número ...

Petróleo, Royalties e Pobreza

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Gicélia Mendes da Silva

2009-08-01

Full Text Available A exploração do petróleo se constitui num elemento significativo para a economia sergipana. A contradição existente entre o subsolo rico e a população pobre levanta indagações a respeito da gestão destes recursos e as condições de vida da população. Tais condições, aliadas à entrada de novos atores na exploração do petróleo em Sergipe e à gestão dos recursos advindos da exploração, vêm incutindo relações peculiares à política neoliberal na região e em Sergipe. O estudo foi desenvolvido a partir da análise e cruzamento de informações disponíveis na Agência Nacional do Petróleo (ANP, Instituto Brasileiro de Geografia e Estatística (IBGE, Tribunal de Contas da União (TCU e PETROBRAS, dentre outros setores. A carência de políticas sociais que ofereçam às populações condições de inserção nas questões política, econômica e social da região produtora de petróleo tem impedido o desenvolvimento efetivo e mudança no padrão de vida das populações, evidenciando a incoerência entre os altos valores depositados nos cofres públicos municipais decorrentes dos royalties e os elevados índices de pobreza apresentados na região. Tal constatação reforça a ideia de que as políticas públicas devem primar pela redução da desigualdade a partir da gestão responsável dos recursos públicos. Abstract OIL, ROYALTIES AND POVERTY The exploitation of oil has significant element for the Sergipe´s economy. However, the contradiction between the subsoils rich and poor people raises key questions about the management of these resources and the living conditions of the population. Such conditions, the entry of new actors in the scenery for the exploration of oil in Sergipe and the management of resources of exploration, instilling relations peculiar to neo-liberal policy in the region and in Sergipe. The study was developed from the analysis and crossing of information available in the national agency oil (ANP

Avaliação toxicológica do óleo essencial de Piper aduncum L.

Directory of Open Access Journals (Sweden)

Pergentino J. C. Sousa

Full Text Available Este trabalho teve como objetivo a avaliação da toxidade aguda e subaguda do óleo essencial de Piper aduncum pela determinação da DL50 em camundongos e a análise dos parâmetros bioquímicos e hematológicos em ratos. A planta é utilizada na medicina popular da região amazônica em diversas doenças e no seu óleo essencial o constituinte majoritário é o fenilpropanóide dilapiol, com propriedades inseticida, fungicida, bactericida, larvicida e moluscicida. A DL50 foi de 2,400 ± 191,7 mg/kg. O óleo essencial não alterou de maneira significativa os parâmetros hematológicos e bioquímicos em relação ao controle no tratamento subagudo, exceto a redução da creatinina. O valor da DL50 e os resultados observados nos parâmetros hematológicos e bioquímicos sugerem que o óleo essencial apresenta toxidade baixa.

The effect of sulphur-terminated GaAs substrates on the MOVPE growth of CuGaS{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Berndt, P.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)]. E-mail: pearl.berndt@nmmu.ac.za; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Branch, M.S. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Leitch, A.W.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Kirmse, H. [Institute of Physics, Chair of Crystallography, Humboldt University of Berlin, Berlin (Germany); Neumann, W. [Institute of Physics, Chair of Crystallography, Humboldt University of Berlin, Berlin (Germany); Weber, J. [Institute for Applied Physics-Semiconductor Physics, University of Technology, Dresden (Germany)

2007-05-31

In this study, various CuGaS{sub 2} layers were grown on GaAs (001) substrates using metalorganic vapour phase epitaxy, for the purpose of studying the effect of sulphur-termination of the substrate on layer quality. The resultant films were investigated using X-ray diffractometry, and transmission electron microscopy, with high-resolution transmission electron microscopy providing additional insights into crystallite growth on the control substrates. This paper will demonstrate that sulphur-termination limits substrate degradation. In the absence of sulphur-termination, atypical three-dimensional MOVPE growth is observed, with epitaxial crystallites varying in size from 10 nm to 200 nm. Substrate degradation inhibits lateral growth at the interface resulting in amorphous regions, cavities, and epitaxial crystallites demonstrating overgrowth into mushroom-like structures.

The effect of sulphur-terminated GaAs substrates on the MOVPE growth of CuGaS2 thin films

International Nuclear Information System (INIS)

Berndt, P.R.; Botha, J.R.; Branch, M.S.; Leitch, A.W.R.; Kirmse, H.; Neumann, W.; Weber, J.

2007-01-01

In this study, various CuGaS 2 layers were grown on GaAs (001) substrates using metalorganic vapour phase epitaxy, for the purpose of studying the effect of sulphur-termination of the substrate on layer quality. The resultant films were investigated using X-ray diffractometry, and transmission electron microscopy, with high-resolution transmission electron microscopy providing additional insights into crystallite growth on the control substrates. This paper will demonstrate that sulphur-termination limits substrate degradation. In the absence of sulphur-termination, atypical three-dimensional MOVPE growth is observed, with epitaxial crystallites varying in size from 10 nm to 200 nm. Substrate degradation inhibits lateral growth at the interface resulting in amorphous regions, cavities, and epitaxial crystallites demonstrating overgrowth into mushroom-like structures

Alterações oxidativas em óleos de algodão, girassol e palma utilizados em frituras de mandioca palito congelada

Directory of Open Access Journals (Sweden)

M. S. CORSINI

2008-10-01

Full Text Available

O presente trabalho teve como objetivo avaliar as alterações oxidativas produzidas nos óleos de algodão, girassol e palma, durante o processo de fritura descontínua de mandioca palito congelada. As frituras foram conduzidas em uma fritadeira elétrica doméstica, onde o óleo foi aquecido, à temperatura de 180°C, por 25 horas, com reposição de óleo fresco. Os resultados obtidos das determinações analíticas foram submetidos às análises de variância, em esquema fatorial, no delineamento inteiramente casualizado, de modo a determinar a influência dos fatores óleos e tempos de fritura sobre as alterações nos óleos e no produto. Os resultados mostraram que as menores alterações ocorreram para o óleo de palma, mais saturado. Para os óleos de algodão e girassol, mais insaturados, verificou-se que ao longo dos tempos de frituras ocorreu um aumento da formação dos compostos de degradação e diminuiu a estabilidade oxidativa. Apesar das diferenças na composição em ácidos graxos, os óleos estudados não apresentaram, em nenhuma análise, valores acima dos limites recomendados, independentemente do tempo de aquecimento. PALAVRAS-CHAVE: Óleos vegetais; alterações oxidativas; estabilidade oxidativa; frituras.

Epitaxial III-V nanowires on silicon for vertical devices

NARCIS (Netherlands)

Bakkers, E.P.A.M.; Borgström, M.T.; Einden, Van Den W.; Weert, van M.H.M.; Helman, A.; Verheijen, M.A.

2006-01-01

We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the Vapor-Liquid-Solid (VLS) mechanism with laser ablation as well as metal organic vapor phase epitaxy. The VLS growth enables the fabrication of complex axial and radial

De novo unbalanced translocation (4p duplication/8p deletion) in a patient with autism, OCD, and overgrowth syndrome.

Science.gov (United States)

Sagar, Angela; Pinto, Dalila; Najjar, Fedra; Guter, Stephen J; Macmillan, Carol; Cook, Edwin H

2017-06-01

Chromosomal abnormalities, such as unbalanced translocations and copy number variants (CNVs), are found in autism spectrum disorders (ASDs) [Sanders et al. (2011) Neuron 70: 863-885]. Many chromosomal abnormalities, including sub microscopic genomic deletions and duplications, are missed by G-banded karyotyping or Fragile X screening alone and are picked up by chromosomal microarrays [Shen et al. (2010) Pediatrics 125: e727-735]. Translocations involving chromosomes 4 and 8 are possibly the second most frequent translocation in humans and are often undetected in routine cytogenetics [Giglio et al. (2002) Circulation 102: 432-437]. Deletions of 4p16 have been associated with Wolf-Hirschhorn syndrome while 4p16 duplications have been associated with an overgrowth syndrome and mild to moderate mental retardation [Partington et al. (1997) Journal of Medical Genetics 34: 719-728]. The 8p23.3 region contains the autism candidate gene DLGAP2, which can contribute to autism when disrupted [Marshall et al. (2008) The American Journal of Human Genetics 82: 477-488] . There has been a case report of a family with autism spectrum disorder (ASD), prominent obsessional behavior, and overgrowth in patients with der (8) t (4;8) p (16;23) [Partington et al. (1997)]. This is an independent report of a male patient with autism, obsessive compulsive disorder (OCD), attention-deficit hyperactivity disorder (ADHD), and an overgrowth syndrome, whose de novo unbalanced translocation der (8) t (4;8) p (16.1→ter; 23.1→ter) was initially missed by routine cytogenetics but detected with SNP microarray, allowing higher resolution of translocation breakpoints. © 2017 Wiley Periodicals, Inc.

Manipulation of Dirac cones in metal-intercalated epitaxial graphene

Science.gov (United States)

Wang, Cai-Zhuang; Kim, Minsung; Tringides, Michael; Ho, Kai-Ming

Graphene is one of the most attractive materials from both fundamental and practical points of view due to its characteristic Dirac cones. The electronic property of graphene can be modified through the interaction with substrate or another graphene layer as illustrated in few-layer epitaxial graphene. Recently, metal intercalation became an effective method to manipulate the electronic structure of graphene by modifying the coupling between the constituent layers. In this work, we show that the Dirac cones of epitaxial graphene can be manipulated by intercalating rare-earth metals. We demonstrate that rare-earth metal intercalated epitaxial graphene has tunable band structures and the energy levels of Dirac cones as well as the linear or quadratic band dispersion can be controlled depending on the location of the intercalation layer and density. Our results could be important for applications and characterizations of the intercalated epitaxial graphene. Supported by the U.S. DOE-BES under Contract No. DE-AC02-07CH11358.

Epitaxial Growth and Cracking Mechanisms of Thermally Sprayed Ceramic Splats

Science.gov (United States)

Chen, Lin; Yang, Guan-jun

2018-02-01

In the present study, the epitaxial growth and cracking mechanisms of thermally sprayed ceramic splats were explored. We report, for the first time, the epitaxial growth of various splat/substrate combinations at low substrate temperatures (100 °C) and large lattice mismatch (- 11.26%). Our results suggest that thermal spray deposition was essentially a liquid-phase epitaxy, readily forming chemical bonding. The interface temperature was also estimated. The results convincingly demonstrated that atoms only need to diffuse and rearrange over a sufficiently short range during extremely rapid solidification. Concurrently, severe cracking occurred in the epitaxial splat/substrate systems, which indicated high tensile stress was produced during splat deposition. The origin of the tensile stress was attributed to the strong constraint of the locally heated substrate by its cold surroundings.

The Oldest Stars of the Extremely Metal-Poor Local Group Dwarf Irregular Galaxy Leo A

Science.gov (United States)

Schulte-Ladbeck, Regina E.; Hopp, Ulrich; Drozdovsky, Igor O.; Greggio, Laura; Crone, Mary M.

2002-08-01

We present deep Hubble Space Telescope (HST) single-star photometry of Leo A in B, V, and I. Our new field of view is offset from the centrally located field observed by Tolstoy et al. in order to expose the halo population of this galaxy. We report the detection of metal-poor red horizontal branch stars, which demonstrate that Leo A is not a young galaxy. In fact, Leo A is as least as old as metal-poor Galactic Globular Clusters that exhibit red horizontal branches and are considered to have a minimum age of about 9 Gyr. We discuss the distance to Leo A and perform an extensive comparison of the data with stellar isochrones. For a distance modulus of 24.5, the data are better than 50% complete down to absolute magnitudes of 2 or more. We can easily identify stars with metallicities between 0.0001 and 0.0004, and ages between about 5 and 10 Gyr, in their post-main-sequence phases, but we lack the detection of main-sequence turnoffs that would provide unambiguous proof of ancient (>10 Gyr) stellar generations. Blue horizontal branch stars are above the detection limits but difficult to distinguish from young stars with similar colors and magnitudes. Synthetic color-magnitude diagrams show it is possible to populate the blue horizontal branch in the halo of Leo A. The models also suggest ~50% of the total astrated mass in our pointing to be attributed to an ancient (>10 Gyr) stellar population. We conclude that Leo A started to form stars at least about 9 Gyr ago. Leo A exhibits an extremely low oxygen abundance, only 3% of solar, in its ionized interstellar medium. The existence of old stars in this very oxygen-deficient galaxy illustrates that a low oxygen abundance does not preclude a history of early star formation. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Redução de inóculo de Aphelenchoides besseyi em sementes de Brachiaria brizantha tratadas com óleos essenciais

Directory of Open Access Journals (Sweden)

Thalita Suelen Avelar Monteiro

2014-07-01

Full Text Available Óleos essenciais foram testados com o objetivo de controlar Aphelenchoides besseyi em sementes de Brachiaria brizantha cv. 'Marandu'. Sementes naturalmente infestadas por A. besseyi foram tratadas com óleos essenciais de mostarda (Brassica nigra, canela (Cinnamomum zeylanicum, verbena (Lippia citriodora e Bioprotector (r (produto comercial composto por extratos e óleos essenciais derivados de plantas, nas concentrações de 0,5% e 1,0%. Avaliou-se também o efeito dos tratamentos após aplicação direta nos juvenis (ensaio in vitro. Todos os óleos tiveram sua efetividade reduzida no ensaio em semente (in vivo em relação ao ensaio in vitro. Os tratamentos não erradicaram o nematoide das sementes, sendo que os óleos essenciais de canela e verbena, nas concentrações 0,5% e 1,0%, Bioprotector (r a 1,0% e óleo de mostarda a 1,0% reduziram o nível populacional do nematoide em sementes contaminadas. O óleo de mostarda a 1,0% destacou-se dos demais por ter apresentado ação nematicida sem alterar a germinação das sementes.

Epitaxial growth of SrTiO3 thin film on Si by laser molecular beam epitaxy

International Nuclear Information System (INIS)

Zhou, X. Y.; Miao, J.; Dai, J. Y.; Chan, H. L. W.; Choy, C. L.; Wang, Y.; Li, Q.

2007-01-01

SrTiO 3 thin films have been deposited on Si (001) wafers by laser molecular beam epitaxy using an ultrathin Sr layer as the template. X-ray diffraction measurements indicated that SrTiO 3 was well crystallized and epitaxially aligned with Si. Cross-sectional observations in a transmission electron microscope revealed that the SrTiO 3 /Si interface was sharp, smooth, and fully crystallized. The thickness of the Sr template was found to be a critical factor that influenced the quality of SrTiO 3 and the interfacial structure. Electrical measurements revealed that the SrTiO 3 film was highly resistive

Growth and characterization of Hg 1– Cd Te epitaxial films by ...

Indian Academy of Sciences (India)

Growth of Hg1–CdTe epitaxial films by a new technique called asymmetric vapour phase epitaxy (ASVPE) has been carried out on CdTe and CZT substrates. The critical problems faced in normal vapour phase epitaxy technique like poor surface morphology, composition gradient and dislocation multiplication have ...

Hinnangud võtmeesinejatele / Leo Voogt ; inglise keelest tõlkinud Kristina Pai

Index Scriptorium Estoniae

Voogt, Leo

2012-01-01

Euroopa teadusraamatukogude organisatsiooni LIBER-i tegevdirektori Leo Voogti seisukohad Tartus 27.-30. juunil 2012 peetud konverentsi ettekandjate kohta, lisaks konverentsi ankeetides tagasisidena kajastunu

Criação de valor sustentável e o óleo de palma no Brasil

OpenAIRE

Almeida, Julio Ribeiro

2012-01-01

A produção de óleo de palma expandiu-se consideravelmente nas últimas décadas e atualmente o óleo de palma é o óleo vegetal mais comercializado do mundo. Dentre outros fatores, a maior produtividade da cultura e os menores custos de produção explicam o crescimento. Os grandes produtores mundiais, contudo, destruíram grandes áreas de floresta para acomodar o crescimento da plantação e se utilizaram de técnicas de cultivo que trouxeram severos impactos ambientais. Campanhas lider...

The binary fraction of stars in dwarf galaxies: the case of Leo II

OpenAIRE

Spencer, Meghin; Mateo, Mario; Walker, Matthew; Olszewski, Edward; McConnachie, Alan; Kirby, Evan; Koch, Andreas

2017-01-01

We combine precision radial velocity data from four different published works of the stars in the Leo II dwarf spheroidal galaxy. This yields a data set that spans 19 years, has 14 different epochs of observation, and contains 372 unique red giant branch stars, 196 of which have repeat observations. Using this multi-epoch data set, we constrain the binary fraction for Leo II. We generate a suite of Monte Carlo simulations that test different binary fractions using Bayesian analysis and determ...

Compensation of an attitude disturbance torque caused by magnetic substances in LEO satellites

Science.gov (United States)

Inamori, Takaya; Wang, Jihe; Saisutjarit, Phongsatorn; Ohsaki, Hiroyuki

This research considers an attitude disturbance torque caused by ferromagnetic substances in a LEO satellite. In most LEO satellite missions, a gravity gradient torque, solar pressure torque, aerodynamic torque, and magnetic dipole moment torque are considered for their attitude control systems, however, the effect of the ferromagnetic substances causing a disturbance torque in the geomagnetic field is not considered in previous satellite missions. The ferromagnetic substances such as iron cores of MTQs and a magnetic hysteresis damper for a passive attitude control system are used in various small satellites. These substances cause a disturbance torque which is almost the same magnitude of the dipole magnetic disturbance and the dominant disturbance in the worst cases. This research proposes a method to estimate and compensate for the effect of the ferromagnetic substances using an extended Kalman filter. From simulation results, the research concludes that the proposed method is useful and attractive for precise attitude control for LEO satellite missions.

Avaliação de óleo essencial de Eucalyptus urograndis(Myrtaceae no controle de Pentatomidae

Directory of Open Access Journals (Sweden)

Taciany Ferreira de Souza

Full Text Available O objetivo dessa pesquisa foi avaliar o potencial inseticida do óleo essencial de Eucalyptus urograndis para o controle de ninfas e adultos de Euschistus heros (Fabricius, 1794 em bioensaios de laboratório. Foram avaliados quatro parâmetros em ninfas e adultos dessa espécie: exposição por aplicação tópica, exposição em superfície de contato, fagoinibição sem chance de escolha e fagoinibição com dupla chance de escolha. A avaliação, observando-se o número de indivíduos vivos e mortos, foi feita no período de 24 e 48 horas. Constatou-se que óleo essencial de E. urograndis é tóxico para ninfas e adultos de E. heros. Tanto as Doses Letais (DL como as Concentrações Letais (CL determinadas para o óleo diminuíram à medida que aumentou o tempo de exposição dos insetos e a dose aplicada do óleo essencial, indicando uma dependência com o tempo de exposição. Verificou-se que as sementes tratadas com óleo essencial provocaram ação fagoinibidora reduzindo os pontos de alimentação, mostrando-se promissor para o controle alternativo desse inseto.

Handover aspects for a Low Earth Orbit (LEO) CDMA Land Mobile Satellite (LMS) system

Science.gov (United States)

Carter, P.; Beach, M. A.

1993-01-01

This paper addresses the problem of handoff in a land mobile satellite (LMS) system between adjacent satellites in a low earth orbit (LEO) constellation. In particular, emphasis is placed on the application of soft handoff in a direct sequence code division multiple access (DS-CDMA) LMS system. Soft handoff is explained in terms of terrestrial macroscopic diversity, in which signals transmitted via several independent fading paths are combined to enhance the link quality. This concept is then reconsidered in the context of a LEO LMS system. A two-state Markov channel model is used to simulate the effects of shadowing on the communications path from the mobile to each satellite during handoff. The results of the channel simulation form a platform for discussion regarding soft handoff, highlighting the potential merits of the scheme when applied in a LEO LMS environment.

Composição química e atividade in vitro de três óleos essenciais sobre Colletotrichum gloeosporioides do maracujazeiro

Directory of Open Access Journals (Sweden)

C.F. Aquino

2014-01-01

Full Text Available Objetivou-se avaliar a ação de diferentes concentrações de óleos essenciais de três plantas medicinais sobre o crescimento micelial, a produção e a germinação de conídios de Colletotrichum gloeosporioides (Penz.. Utilizou-se os óleos essenciais de Lippia sidoides Cham., Cymbopogon citratus (DC Stapf. e Ocimum gratissimum L. em cinco concentrações (0 µL mL-1, 1 µL mL-1, 3 µL mL-1, 5 µL mL-1 e 7 µL mL-1 com 4 repetições no delineamento inteiramente casualizado, em esquema fatorial 5x3. Os óleos foram analisados por cromatografia gasosa acoplada com espectrometria de massas. Para todas as características verificou-se efeito significativo da interação "Óleo" versus "Concentração". O óleo essencial de C. citratus proporcionou a maior inibição do crescimento micelial em todas as concentrações testadas. Os outros óleos não se diferenciaram, exceto a partir da concentração de 5 µL mL-1, onde o óleo de L. sidoides foi superior ao óleo de O. gratissimum. Na produção e germinação de conídios, o óleo de C. citratus, foi superior aos óleos de L. sidoides e de O. gratissimum nas concentrações de 1 µL mL-1 e 3 µL mL-1, inibindo completamente a produção e germinação a partir da concentração de 3 µL mL-1. As concentrações influenciam em todas as variáveis, ajustando-se à equação do modelo linear. Observa-se o decréscimo nessas, à medida em que se aumentam as concentrações dos óleos testados. Os óleos essenciais testados possuem efeito fungitóxico e fungistático.

Reciclo-óleo: do óleo de cozinha ao sabão ecológico, um projeto de educação ambiental

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Maria Isabel Morgan Martins

2016-10-01

Full Text Available O consumo de óleo faz parte do dia-a-dia das famílias, restaurantes, indústrias e com ele o descarte incorreto do óleo de cozinha usado (OCU se torna um grave problema ambiental. Quando despejado no lixo comum impermeabiliza e contamina o solo, porque a decomposição aumenta o efeito estufa, na rede de esgoto compromete as tubulações das residências e das cidades e ao atingir os rios forma uma película na água que impede a passagem de luz e oxigênio a flora e a fauna aquática. Objetivo: é promover a educação ambiental para o descarte correto e a reciclagem do óleo de cozinha usado, transformando-o em sabão em barra ecológico, gerando renda e sustentabilidade. Método/ atividades de extensão: o projeto apresenta duas linhas bem definidas à educação ambiental e o desenvolvimento de receitas que transformam do OCU em sabão em barra ecológico. O projeto educa para a consciência e responsabilidade ambiental a diferentes grupos da comunidade, ensina e orienta a importância de dar o destino correto ao OCU, bem como, a reciclagem com sustentabilidade, criando alternativa de geração de renda. Desde 2010, as oficinas foram realizadas em diferentes bairros, escolas e empresas dos municípios da grande Porto Alegre, RS. As receitas foram desenvolvidas no laboratório do campus da ULBRA Gravataí, e apresentam baixo custo, para a fabricação “caseira” do sabão ecológico. O primeiro processo é educar com consciência ambiental. Considerações finais: o reciclo-óleo contribui para o combate à poluição e manutenção dos recursos naturais. Portanto, com ações de educação em saúde é possível refletir positivamente na preservação do meio ambiente, contribuindo, dessa forma, para o desenvolvimento sustentável e para a promoção da saúde das cidades.

The Leo I color-magnitude diagram

International Nuclear Information System (INIS)

Reid, N.; Mould, J.

1991-01-01

The R-and I-band photometry of the Leo I dwarf galaxy is presented. A relatively narrow giant branch is found, Implying an abundance range of no more than Fe/H/= - 0.7 to - 1.3. This is in contrast to the results is found by Fox and Pritchet (1987) from BV CCD photometry. The distance modulus is estimated as (m - M) = 21.85 + or - 0.15, based on the luminosity of the tip of the red giant branch. 15 refs

Uso de óleo essencial de orégano, salinomicina e bacitracina de zinco na dieta de frangos de corte

Directory of Open Access Journals (Sweden)

Patricia Maria Meneghetti Pulici

2014-09-01

Full Text Available O presente trabalho teve como objetivo avaliar dietas com óleo essencial de orégano, associado ou não com salinomicina, como alternativa à bacitracina de zinco sobre o desempenho zootécnico de frangos de corte. Foram utilizados 600 pintos de um dia de idade, machos, da linhagem Cobb® 500, criados até 42 dias de idade em boxes com cama de casca de arroz providos de comedouros tubulares e bebedouros nipple. O delineamento foi inteiramente casualizado, com seis dietas e 10 repetições de 10 aves cada. As dietas experimentais à base de milho e farelo de soja foram: controle positivo – antibiótico (bacitracina de zinco + 0,05% de anticoccidiano (salinomicina, controle negativo – dieta basal (DB sem aditivos, DB + 0,05% de salinomicina e 0,03% de óleo essencial de orégano (Orego-Stim®, DB + 0,03% de óleo essencial de orégano, DB + 0,05% de salinomicina e 0,05% de óleo essencial de orégano, DB + 0,05% de óleo essencial de orégano. Não foi encontrado efeito da utilização do óleo de orégano até 21 dias no desempenho das aves. Nos demais períodos, aos 35 e 42 dias, o desempenho das aves tratadas com 0,03% de óleo essencial de orégano + salinomicina apresentou resultados semelhantes ao controle positivo, levando à conclusão de que a dose de 0,03% de óleo essencial de orégano + salinomicina pode substituir a bacitracina de zinco + salinomicina em dietas para frangos de corte.

In memoriam Prof. Dr. Leo Daniel Brongersma (1907-1994)

NARCIS (Netherlands)

Hoogmoed, M.S.

1995-01-01

A biography of Leo Daniel Brongersma is given, highlighting his significance for herpetology worldwide, and especially for snake anatomy, sea turtle distribution, faunistics of New Guinea and IndoAustralia. Lists of patronyms, of species named by Brongersma and of his publications are given. Also

Epitaxial growth of ZnO layers on (111) GaAs substrates by laser molecular beam epitaxy

International Nuclear Information System (INIS)

Ding Jian; Zhang Di; Konomi, Takaharu; Saito, Katsuhiko; Guo Qixin

2012-01-01

ZnO layers were grown on (111) GaAs substrates by laser molecular epitaxy at substrate temperatures between 200 and 550 °C. X-ray diffraction analysis revealed that c-axis of ZnO epilayer with a wurtzite structure is perpendicular to the substrate surface. X-ray rocking curves and Raman spectroscopy showed that the crystal quality of ZnO epilayers depends on the substrate temperature during the growth. Strong near-band-edge emission in the UV region without any deep-level emissions was observed from the ZnO epilayers at room temperature. The results indicate that laser molecular beam epitaxy is a promising growth method for obtaining high-quality ZnO layers on (111) GaAs substrates.

Effect of growth temperature on defects in epitaxial GaN film grown by plasma assisted molecular beam epitaxy

Directory of Open Access Journals (Sweden)

S. S. Kushvaha

2014-02-01

Full Text Available We report the effect of growth temperature on defect states of GaN epitaxial layers grown on 3.5 μm thick GaN epi-layer on sapphire (0001 substrates using plasma assisted molecular beam epitaxy. The GaN samples grown at three different substrate temperatures at 730, 740 and 750 °C were characterized using atomic force microscopy and photoluminescence spectroscopy. The atomic force microscopy images of these samples show the presence of small surface and large hexagonal pits on the GaN film surfaces. The surface defect density of high temperature grown sample is smaller (4.0 × 108 cm−2 at 750 °C than that of the low temperature grown sample (1.1 × 109 cm−2 at 730 °C. A correlation between growth temperature and concentration of deep centre defect states from photoluminescence spectra is also presented. The GaN film grown at 750 °C exhibits the lowest defect concentration which confirms that the growth temperature strongly influences the surface morphology and affects the optical properties of the GaN epitaxial films.

MODELAGEM TERMODINÂMICA DO FRACIONAMENTO DO ÓLEO DE MANTEIGA COM FLUIDOS SUPERCRÍTICOS

Directory of Open Access Journals (Sweden)

Guilherme B. M. NEVES

1997-12-01

Full Text Available O fracionamento do óleo de manteiga em frações de propriedades físicas e químicas diferentes mostra-se uma possível solução para o problema do excedente de óleo de manteiga no mercado internacional, despertando interesse em seu estudo. Com o objetivo de se modelar o equilíbrio de fases neste processo, foi feito um agrupamento dos 1331 triglicerídeos presentes no óleo de manteiga em 14 famílias. Assim, os componentes de uma mesma família possuem um comportamento semelhante quando expostos ao CO2 Supercrítico (CO2 SC. A seguir, utilizando a Equação de Peng-Robinson, realizou-se o cálculo do equilíbrio de fases no sistema óleo de manteiga/CO2, sendo o óleo de manteiga representado por uma mistura de 14 componentes hipotéticos, as famílias. Foram desenvolvidas correlações para a temperatura e pressão críticas e parâmetros de interação binária das famílias. O modelo foi capaz de correlacionar dados obtidos da literatura. As predições do equilíbrio de fases estão em excelente concordância com os dados obtidos pelos autores deste trabalho para os sistemas de óleo de manteiga/CO2. O procedimento mostrado aqui aplica-se não só ao dióxido de carbono supercrítico mas também a outros fluidos ou misturas de fluidos supercríticos, e também não somente ao óleo de manteiga, mas a todos os óleos/gorduras cuja constituição principal sejam triglicerídeos.Fractionation of butter oil into fractions with different physical and chemical properties is a possible solution for the problem of the excess of butter oil in the international market. With the objective of modeling the phase equilibria, the 1331 triglycerides were grouped into 14 families according to the number of carbons. Components belonging to the same family are considered to exhibit similar behavior when exposed to supercritical carbon dioxide (SC CO2. Using the Peng-Robinson equation of state, phase equilibrium calculations were performed for the butter

Crystallization engineering as a route to epitaxial strain control

Directory of Open Access Journals (Sweden)

Andrew R. Akbashev

2015-10-01

Full Text Available The controlled synthesis of epitaxial thin films offers opportunities for tuning their functional properties via enabling or suppressing strain relaxation. Examining differences in the epitaxial crystallization of amorphous oxide films, we report on an alternate, low-temperature route for strain engineering. Thin films of amorphous Bi–Fe–O were grown on (001SrTiO3 and (001LaAlO3 substrates via atomic layer deposition. In situ X-ray diffraction and X-ray photoelectron spectroscopy studies of the crystallization of the amorphous films into the epitaxial (001BiFeO3 phase reveal distinct evolution profiles of crystallinity with temperature. While growth on (001SrTiO3 results in a coherently strained film, the same films obtained on (001LaAlO3 showed an unstrained, dislocation-rich interface, with an even lower temperature onset of the perovskite phase crystallization than in the case of (001SrTiO3. Our results demonstrate how the strain control in an epitaxial film can be accomplished via its crystallization from the amorphous state.

Óleos essenciais de folhas de diversas espécies: propriedades antioxidantes e antibacterianas no crescimento espécies patogênicas

Directory of Open Access Journals (Sweden)

Cíntia Alvarenga Santos Fraga Miranda

Full Text Available RESUMO Os óleos essenciais apresentam possibilidade de serem empregados nas indústrias de alimentos, bebidas, produtos de higiene pessoal e cosméticos para evitar ou reduzir a deterioração lipídica e a contaminação por micro-organismos. Este trabalho teve como objetivos avaliar as propriedades funcionais antimicrobianas e antioxidantes de óleos essenciais de folhas frescas de Coniza bonariensis, Parthenium hysterophorus, Tithonia diversifolia, Ambrosia polystachya, Hedychium coronarium e Baccharis dracunculifolia, extraídos por hidrodestilação. O potencial antioxidante foi avaliado pelas metodologias do consumo do radical DPPH e da inibição da oxidação do sistema β-caroteno/ácido linoleico. A sensibilidade das bactérias Salmonella Cholerasuis, Listeria monocytogenes, Staphylococcus aureus e Escherichia coli frente aos óleos essenciais foi determinada pela utilização do método de difusão em cavidade ágar. Os óleos essenciais destacaram-se pelo elevado conteúdo de terpenoides. Todos os óleos essenciais avaliados pela metodologia do sequestro do radical DPPH não apresentaram CI50 significativos. Pela metodologia do β-caroteno/ácido linoleico, os óleos essenciais de T. diversifolia e H. coronarium não apresentaram atividades significativas e os de C. bonariensis, P. hysterophorus, A. polystachya, e B. dracunculifolia apresentaram CI50 superiores a maior concentração avaliada. Os óleos essenciais das espécies C. bonariensis, T. diversifolia, H. coronarium e de B. dracunculifolia apresentaram atividade antibacteriana para bactérias Gramnegativas e Gram-positivas, com exceção do óleo volátil de P. hysterophorus, que não impediu o crescimento de nenhuma das cepas bacterianas testadas. O óleo essencial de A. polystachya apresentou potencial antibacteriano apenas nas cepas de S. aureus.

Clinical case report of long-term follow-up in type-2 diabetes patient with severe chronic periodontitis and nifedipine-induced gingival overgrowth.

Science.gov (United States)

Shibukawa, Yoshihiro; Fujinami, Koushu; Yamashita, Shuichiro

2012-01-01

In this case report, we describe the clinical course over a 14-year follow-up in a 47-year-old diabetes patient with severe chronic periodontitis and nifedipine-induced gingival overgrowth. The patient had a history of hypertension for over 5 years and uncontrolled type 2 diabetes. Overgrown gingiva was observed in most of the teeth and was marked in the upper and lower anterior teeth. A probing pocket depth of ≥ 4 mm and bleeding on probing (BOP) were observed in 94 and 90% of sites examined, respectively. At baseline, his hemoglobin A1c (HbA1c) was 8.5%. The patient received periodontal and diabetic treatment simultaneously. Medication was changed from nifedipine chloride to an angiotensin-converting enzyme inhibitor. After initial therapy and subsequent periodontal surgery, gingival overgrowth disappeared and probing depth and BOP showed a significant improvement. No recurrence was observed during supportive periodontal therapy (SPT). The HbA1c level improved from 8.5 to 6.3% after periodontal treatment, subsequently remaining at a good level during SPT over 10 years. This study demonstrated that periodontal treatment, withdrawal of medication and control of diabetes can result in remarkable improvements in type 2 diabetes patients with chronic periodontitis and nifedipine-induced gingival overgrowth. These results suggest that comprehensive periodontal treatment in combination with treatment for diabetes mellitus can exert a positive influence on blood glucose levels and periodontal condition in diabetic patients.

Establishing a Robotic, LEO-to-GEO Satellite Servicing Infrastructure as an Economic Foundation for Exploration

Science.gov (United States)

Horsham, Gary A. P.; Schmidt, George R.; Gilland, James H.

2010-01-01

The strategy for accomplishing civilian exploration goals and objectives is in the process of a fundamental shift towards a potential new approach called Flexible Path. This paper suggests that a government-industry or public-private partnership in the commercial development of low Earth orbit to geostationary orbit (LEO-to-GEO (LTG)) space, following or in parallel with the commercialization of Earth-to-LEO and International Space Station (ISS) operations, could serve as a necessary, logical step that can be incorporated into the flexible path approach. A LTG satellite-servicing infrastructure and architecture concept is discussed within this new strategic context. The concept consists of a space harbor that serves as a transport facility for a fleet of specialized, fully- or semi-autonomous robotic servicing spacecraft. The baseline, conceptual system architecture is composed of a space harbor equipped with specialized servicer spacecraft; a satellite command, communication, and control system; a parts station; a fuel station or depot; and a fuel/parts replenishment transport. The commercial servicer fleet would consist of several types of spacecraft, each designed with specialized robotic manipulation subsystems to provide services such as refueling, upgrade, repair, inspection, relocation, and removal. The space harbor is conceptualized as an ISS-type, octagonal truss structure equipped with radiation tolerant subsystems. This space harbor would be primarily capable of serving as an operational platform for various commercially owned and operated servicer spacecraft positioned and docked symmetrically on four of the eight sides. Several aspects of this concept are discussed, such as: system-level feasibility in terms of ISS-truss-type infrastructure and subsystems emplacement and maintenance between LEO and GEO; infrastructure components assembly in LEO, derived from ISS assembly experience, and transfer to various higher orbital locations; the evolving Earth

Capacidade antioxidante total de óleos vegetais comestíveis: determinantes químicos e sua relação com a qualidade dos óleos Total antioxidant capacity of edible vegetable oils: chemical determinants and associations with oil quality

Directory of Open Access Journals (Sweden)

Vanessa Naciuk Castelo-Branco

2011-02-01

Full Text Available A capacidade antioxidante total de óleos vegetais comestíveis é determinada por sua composição físico-química e pode estar associada a atributos de qualidade dos óleos, especialmente a sua bioatividade e possivelmente a sua estabilidade oxidativa. Este artigo apresenta os fundamentos dos ensaios de capacidade antioxidante total e avalia criticamente os ensaios aplicáveis na análise de óleos e os pontos críticos nas aplicações dos ensaios para a análise dessas amostras. Discute-se o potencial papel dos componentes químicos dos óleos comestíveis como determinantes da capacidade antioxidante total, assim como a possível relação da capacidade antioxidante com a bioatividade e a estabilidade oxidativa dos óleos. Finalmente, discutem-se evidências de que, caso seja sistematicamente investigado em trabalhos experimentais futuros, o uso de ensaios de capacidade antioxidante total na análise de óleos vegetais pode contribuir para integrar o conhecimento da composição química com a bioatividade e possivelmente com a estabilidade de óleos vegetais específicos. Dessa forma, os ensaios de capacidade antioxidante apresentam potencial para aplicação no controle da qualidade integral de óleos comestíveis.The total antioxidant capacity of edible vegetable oils is determined by their physical-chemical composition and might be associated with their quality attributes, especially with bioactivity and possibly with oxidative stability. The current review presents the fundamentals of total antioxidant capacity assays and critically evaluates the assays applicable to the analysis of oils. The role of the chemical components of edible oils as determinants of total antioxidant capacity is discussed, as well as the potential associations between antioxidant capacity and bioactivity or oxidative stability of the selected oils. Finally, we discuss evidences that, if systematically addressed in future experimental work, the application of

Haemangiosarcoma in a captive Asiatic lion ( Panthera leo persica ...

African Journals Online (AJOL)

A 2.7-year-old male captive Asiatic lion (Panthera leo persica) died unexpectedly without preceding symptoms. Gross necropsy revealed liver and lung tumours, which proved to be haemangiosarcomas by histopathology. Some of the liver tumours were ruptured, leading to massive intra-abdominal haemorrhage and death.

Optimization of GaN Nanorod Growth Conditions for Coalescence Overgrowth

Science.gov (United States)

2016-02-04

21, 2016 PI: Chih-Chung (C. C.) Yang, ccycc@ntu.edu.tw Graduate Institute of Photonics and Optoelectronics, National Taiwan University...nanowire light emitting diodes grown on (001) silicon by molecular beam epitaxy, Nano Lett. 10 (2010) 3355-3359. [16] W. Guo, A. Banerjee, P...Bhattacharya, B.S. Ooi, InGaN/GaN disk-in-nanowire white light emitting diodes on (001) silicon , Appl. Phys. Lett. 98 (2011) 193102. [17] H.P.T. Nguyen, M

PRODUÇÃO DE PETRÓLEO E IMPACTOS AMBIENTAIS: ALGUMAS CONSIDERAÇÕES

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Silas Sarkiz da Silva Martins

2015-12-01

Full Text Available O petróleo está a cada dia sendo mais explorado e tem sido um recurso energético gerador de divisas para a economia de países e nações, a exemplo do Brasil, mas, também, difusor de impactos ambientais negativos. As etapas que envolvem a produção de petróleo desde a perfuração de poços até o refino, direta ou indiretamente, têm causado alterações ao meio ambiente. O objetivo deste estudo foi o de compreender os principais impactos ambientais gerados pelas etapas de produção de petróleo, considerando estudos de impacto ambiental (EIAs e seus respectivos relatórios de impacto ambiental (RIMAs. A avaliação dos impactos ambientais se dá através do diagnóstico ambiental da área de influência do empreendimento, o qual é feito para se conhecer os componentes dos meios físico, biológico e socioeconômico da área e, posteriormente, avaliar os efeitos das atividades do empreendimento sobre os mesmos. Pela complexidade da composição química do petróleo, o risco quanto as suas atividades e seu manuseio é, na maioria dos casos, de grande potencial, pois pode haver acidentes, que, por sua vez, podem interferir negativamente no meio ambiente. Ao término do estudo, concluiu-se que a fase de produção de petróleo apresenta diversos aspectos ambientais, os quais geram impactos. Viu-se que os impactos não são apenas de caráter negativo. E, por fim, sugere-se a aplicação de medidas mitigadoras e de um sistema de gestão ambiental eficaz para a minimização e/ou eliminação de tais impactos.

Growth and characterization of Hg1–xCdxTe epitaxial films by ...

Indian Academy of Sciences (India)

Unknown

Abstract. Growth of Hg1–xCdxTe epitaxial films by a new technique called asymmetric vapour phase epitaxy. (ASVPE) has been carried out on CdTe and CZT substrates. The critical problems faced in normal vapour phase epitaxy technique like poor surface morphology, composition gradient and dislocation multiplication.

Growth of pseudomorphic structures through organic epitaxy

International Nuclear Information System (INIS)

Kaviyil, Sreejith Embekkat; Sassella, Adele; Borghesi, Alessandro; Campione, Marcello; Su Genbo; He Youping; Chen Chenjia

2012-01-01

The control of molecular orientation in thin solid film phases of organic semiconductors is a basic factor for the exploitation of their physical properties for optoelectronic devices. We compare structural and optical properties of thin films of the organic semiconductor α-quarterthiophene grown by molecular beam epitaxy on different organic substrates. We show how epitactic interactions, characteristic of the surface of organic crystals, can drive the orientation of the crystalline overlayer and the selection of specific polymorphs and new pseudomorphic phases. We identify a key role in this phenomenon played by the marked groove-like corrugations present in some organic crystal surfaces. Since different polymorphs possess rather different performance in terms of, e.g., charge carrier mobility, this strategy is demonstrated to allow for the growth of oriented phases with enhanced physical properties, while keeping the substrate at room temperature. These results provide useful guidelines for the design of technological substrates for organic epitaxy and they substantiate the adoption of an organic epitaxy approach for the fabrication of optoelectronic devices based on thin films of organic semiconductors.

Synchrotron radiation excited silicon epitaxy using disilane

International Nuclear Information System (INIS)

Akazawa, Housei; Utsumi, Yuichi

1995-01-01

Synchrotron radiation (SR) excited chemical reactions provide new crystal growth methods suitable for low-temperature Si epitaxy. The growth kinetics and film properties were investigated by atomic layer epitaxy (ALE) and photochemical vapor deposition (CVD) modes using Si 2 H 6 . SR-ALE, isolating the surface growth channel mediated by photon stimulated hydrogen desorption, achieves digital growth independent of gas exposure time, SR irradiation time, and substrate temperature. On the other hand in SR-CVD, photolysis of Si 2 H 6 is predominant. In the nonirradiated region, Eley-Rideal type reaction between the photofragments and the surface deposit Si adatoms in a layer-by-layer fashion. In the irradiated region, however, multi-layer photolysis and rebounding occurs within the condensed Si 2 H 6 layer. The pertinent elementary processes were identified by using the high-resolution time-of-flight mass spectroscopy. The SR-CVD can grow a uniform and epitaxial Si film down to 200degC. The surface morphology is controlled by the surfactant effect of hydrogen atoms. (author)

Microwave dynamics of YBCO bi-epitaxial Josephson structures

DEFF Research Database (Denmark)

Constantinian, K. Y.; Ovsyannikov, G. A.; Mashtakov, A. D.

1996-01-01

The processes of interaction of microwaves (frequency View the MathML source) with a single high-Tc superconducting YBa2Cu3Ox (YBCO) bi-epitaxial grain-boundary junction and with an array of two junctions connected in series, have been investigated experimentally at temperatures T = 4.2− 77 K......, as well as the subharmonic detector response at weak magnetic fields φ microwave field induced frequency synchronization of two series connected bi-epitaxial YBCO junctions....

Ion beam induced epitaxy in Ge- and B- coimplanted silicon

International Nuclear Information System (INIS)

Hayashi, N.; Hasegawa, M.; Tanoue, H.; Takahashi, H.; Shimoyama, K.; Kuriyama, K.

1992-01-01

The epitaxial regrowth of amorphous surface layers in and Si substrate has been studied under irradiation with 400 keV Ar + ions at the temperature range from 300 to 435degC. The amorphous layers were obtained by Ge + implantation, followed by B + implantation. The ion beam assisted epitaxy was found to be sensitive to both the substrate orientation and the implanted Ge concentration, and the layer-by-layer epitaxial regrowth seemed to be precluded in Si layers with high doses of Ge implants, e.g., 2.5 x 10 15 ions/cm 2 . Electrical activation of implanted dopant B was also measured in the recrystallized Si layer. (author)

A new concept for high-cycle-life LEO: Rechargeable MnO2-hydrogen

Science.gov (United States)

Appleby, A. J.; Dhar, H. P.; Kim, Y. J.; Murphy, O. J.

1989-01-01

The nickel-hydrogen secondary battery system, developed in the early 1970s, has become the system of choice for geostationary earth orbit (GEO) applications. However, for low earth orbit (LEO) satellites with long expected lifetimes the nickel positive limits performance. This requires derating of the cell to achieve very long cycle life. A new system, rechargeable MnO2-Hydrogen, which does not require derating, is described here. For LEO applications, it promises to have longer cycle life, high rate capability, a higher effective energy density, and much lower self-discharge behavior than those of the nickel-hydrogen system.

Small intestinal bacterial overgrowth in irritable bowel syndrome: are there any predictors?

Directory of Open Access Journals (Sweden)

McCallum Richard W

2010-02-01

Full Text Available Abstract Background Small intestinal bacterial overgrowth (SIBO is a condition in which excessive levels of bacteria, mainly the colonic-type species are present in the small intestine. Recent data suggest that SIBO may contribute to the pathophysiology of Irritable bowel syndrome (IBS. The purpose of this study was to identify potential predictors of SIBO in patients with IBS. Methods Adults with IBS based on Rome II criteria who had predominance of bloating and flatulence underwent a glucose breath test (GBT to determine the presence of SIBO. Breath samples were obtained at baseline and at 30, 45, 60, 75 and 90 minutes after ingestion of 50 g of glucose dissolved in 150 mL of water. Results of the glucose breath test, which measures hydrogen and methane levels in the breath, were considered positive for SIBO if 1 the hydrogen or methane peak was >20 ppm when the baseline was Results Ninety-eight patients were identified who underwent a GBT (mean age, 49 y; 78% female. Thirty-five patients (36% had a positive GBT result suggestive of SIBO. A positive GBT result was more likely in patients >55 years of age (odds ratio [OR], 3.6; 95% confidence interval [CI], 1.4-9.0 and in females (OR, 4.0; 95% CI, 1.1-14.5. Hydrogen was detected more frequently in patients with diarrhea-predominant IBS (OR, 8; 95% CI, 1.4-45, and methane was the main gas detected in patients with constipation-predominant IBS (OR, 8; 95% CI, 1.3-44. There was no significant correlation between the presence of SIBO and the predominant bowel pattern or concurrent use of tegaserod, proton pump inhibitors, or opiate analgesics. Conclusions Small intestinal bacterial overgrowth was present in a sizeable percentage of patients with IBS with predominance of bloating and flatulence. Older age and female sex were predictors of SIBO in patients with IBS. Identification of possible predictors of SIBO in patients with IBS could aid in the development of successful treatment plans.

Pretreatment with a γ-Secretase Inhibitor Prevents Tumor-like Overgrowth in Human iPSC-Derived Transplants for Spinal Cord Injury

Directory of Open Access Journals (Sweden)

Toshiki Okubo

2016-10-01

Full Text Available Neural stem/progenitor cells (NS/PCs derived from human induced pluripotent stem cells (hiPSCs are considered to be a promising cell source for cell-based interventions that target CNS disorders. We previously reported that transplanting certain hiPSC-NS/PCs in the spinal cord results in tumor-like overgrowth of hiPSC-NS/PCs and subsequent deterioration of motor function. Remnant immature cells should be removed or induced into more mature cell types to avoid adverse effects of hiPSC-NS/PC transplantation. Because Notch signaling plays a role in maintaining NS/PCs, we evaluated the effects of γ-secretase inhibitor (GSI and found that pretreating hiPSC-NS/PCs with GSI promoted neuronal differentiation and maturation in vitro, and GSI pretreatment also reduced the overgrowth of transplanted hiPSC-NS/PCs and inhibited the deterioration of motor function in vivo. These results indicate that pretreatment with hiPSC-NS/PCs decreases the proliferative capacity of transplanted hiPSC-NS/PCs, triggers neuronal commitment, and improves the safety of hiPSC-based approaches in regenerative medicine.

Degradação de óleos lubrificantes em motores estacionários movidos a biogas

Directory of Open Access Journals (Sweden)

Djessica Brum

2018-01-01

Full Text Available Com o crescente interesse do uso de biogás como fonte de energia elétrica por meio de motores ciclo Otto, as condições de trabalho destes motores se tornam relevantes para maior eficiência de conversão energética e maior tempo de uso. A utilização correta de óleos lubrificantes permite ampliar a quantidade de horas motor, sem necessidade de troca. Avaliar a qualidade e a degradação dos óleos lubrificantes neste sistema torna-se uma premissa importante, uma vez que o óleo degradado diminui a capacidade de proteção nas peças móveis do motor e aumenta o superaquecimento do sistema. A contaminação por agentes externos eleva a chance do desenvolvimento de borras e aumentando a corrosão de peças. Este trabalho realizou o controle de qualidade de óleos lubrificantes em motores estacionários movidos a biogás. Os óleos foram analisados por espectrofotometria na região do infravermelho, na qual foram verificadas as bandas de oxidação, presença de água, fuligem, nitratos e sulfato, sendo determinada também a acidez total do óleo lubrificante, de acordo com a norma ASTM D4739, preconizada pela Resolução ANP nº 10/2000. O principal problema encontrado foi a quantidade de água presente nos motores, acima do limite de 0,03%, indicando algum problema de vazamento/contaminação no motor. Os testes controlados com diferentes gases apresentaram pouca variação em relação à comparação com ar, ao controle utilizado e ao gás N2, sendo que os principais parâmetros afetados foram a oxidação e a acidez, pois os outros parâmetros não apresentaram diferenças significativas entre si.

Recent Progress on the Second Generation CMORPH: LEO-IR Based Precipitation Estimates and Cloud Motion Vector

Science.gov (United States)

Xie, Pingping; Joyce, Robert; Wu, Shaorong

2015-04-01

As reported at the EGU General Assembly of 2014, a prototype system was developed for the second generation CMORPH to produce global analyses of 30-min precipitation on a 0.05olat/lon grid over the entire globe from pole to pole through integration of information from satellite observations as well as numerical model simulations. The second generation CMORPH is built upon the Kalman Filter based CMORPH algorithm of Joyce and Xie (2011). Inputs to the system include rainfall and snowfall rate retrievals from passive microwave (PMW) measurements aboard all available low earth orbit (LEO) satellites, precipitation estimates derived from infrared (IR) observations of geostationary (GEO) as well as LEO platforms, and precipitation simulations from numerical global models. Key to the success of the 2nd generation CMORPH, among a couple of other elements, are the development of a LEO-IR based precipitation estimation to fill in the polar gaps and objectively analyzed cloud motion vectors to capture the cloud movements of various spatial scales over the entire globe. In this presentation, we report our recent work on the refinement for these two important algorithm components. The prototype algorithm for the LEO IR precipitation estimation is refined to achieve improved quantitative accuracy and consistency with PMW retrievals. AVHRR IR TBB data from all LEO satellites are first remapped to a 0.05olat/lon grid over the entire globe and in a 30-min interval. Temporally and spatially co-located data pairs of the LEO TBB and inter-calibrated combined satellite PMW retrievals (MWCOMB) are then collected to construct tables. Precipitation at a grid box is derived from the TBB through matching the PDF tables for the TBB and the MWCOMB. This procedure is implemented for different season, latitude band and underlying surface types to account for the variations in the cloud - precipitation relationship. At the meantime, a sub-system is developed to construct analyzed fields of

Characterization of GaN/AlGaN epitaxial layers grown

Indian Academy of Sciences (India)

GaN and AlGaN epitaxial layers are grown by a metalorganic chemical vapour deposition (MOCVD) system. The crystalline quality of these epitaxially grown layers is studied by different characterization techniques. PL measurements indicate band edge emission peak at 363.8 nm and 312 nm for GaN and AlGaN layers ...

Removable polytetrafluoroethylene template based epitaxy of ferroelectric copolymer thin films

Science.gov (United States)

Xia, Wei; Chen, Qiusong; Zhang, Jian; Wang, Hui; Cheng, Qian; Jiang, Yulong; Zhu, Guodong

2018-04-01

In recent years ferroelectric polymers have shown their great potentials in organic and flexible electronics. To meet the requirements of high-performance and low energy consumption of novel electronic devices and systems, structural and electrical properties of ferroelectric polymer thin films are expected to be further optimized. One possible way is to realize epitaxial growth of ferroelectric thin films via removable high-ordered polytetrafluoroethylene (PTFE) templates. Here two key parameters in epitaxy process, annealing temperature and applied pressure, are systematically studied and thus optimized through structural and electrical measurements of ferroelectric copolymer thin films. Experimental results indicate that controlled epitaxial growth is realized via suitable combination of both parameters. Annealing temperature above the melting point of ferroelectric copolymer films is required, and simultaneously moderate pressure (around 2.0 MPa here) should be applied. Over-low pressure (around 1.0 MPa here) usually results in the failure of epitaxy process, while over-high pressure (around 3.0 MPa here) often results in residual of PTFE templates on ferroelectric thin films.

Counteracting wetland overgrowth increases breeding and staging bird abundances

Science.gov (United States)

Lehikoinen, Petteri; Lehikoinen, Aleksi; Mikkola-Roos, Markku; Jaatinen, Kim

2017-01-01

Human actions have led to loss and degradation of wetlands, impairing their suitability as habitat especially for waterbirds. Such negative effects may be mitigated through habitat management. To date scientific evidence regarding the impacts of these actions remains scarce. We studied guild specific abundances of breeding and staging birds in response to habitat management on 15 Finnish wetlands. In this study management actions comprised several means of vegetation removal to thwart overgrowth. Management cost efficiency was assessed by examining the association between site-specific costs and bird abundances. Several bird guilds exhibited positive connections with both habitat management as well as with invested funds. Most importantly, however, red-listed species and species with special conservation concern as outlined by the EU showed positive correlations with management actions, underlining the conservation value of wetland management. The results suggest that grazing was especially efficient in restoring overgrown wetlands. As a whole this study makes it clear that wetland habitat management constitutes a feasible conservation tool. The marked association between invested funds and bird abundance may prove to be a valuable tool for decision makers when balancing costs and impact of conservation measures against one another.

Deposition of HgTe by electrochemical atomic layer epitaxy (EC-ALE)

CSIR Research Space (South Africa)

Venkatasamy, V

2006-04-01

Full Text Available This paper describes the first instance of HgTe growth by electrochemical atomic layer epitaxy (EC-ALE). EC-ALE is the electrochemical analog of atomic layer epitaxy (ALE) and atomic layer deposition (ALD), all of which are based on the growth...

"Winterização" de óleo de pescado via solvente Winterization of fish oil with solvent

Directory of Open Access Journals (Sweden)

Daniele Colembergue Cunha

2009-03-01

Full Text Available O fracionamento de óleos via "winterização" consiste numa cristalização fracionada, na qual os triacilgliceróis de óleos e gorduras são separados pela cristalização parcial na fase líquida. O objetivo deste trabalho consistiu na determinação das variáveis significativas e das condições operacionais do processo de "winterização" via solvente do óleo de pescado. Como matéria-prima empregou-se o óleo de pescado bruto de indústrias pesqueiras, o qual foi branqueado. Na etapa de "winterização", o óleo branqueado foi resfriado progressivamente em três estágios, de 30 ºC até -5 ºC. Foram estudados os seguintes fatores: tipo de solvente, proporção de solvente e agitação no segundo estágio do resfriamento. As composições de ácidos graxos dos óleos de pescado foram determinadas através de cromatografia gasosa. Foram analisadas as variações percentuais dos ácidos graxos insaturados e dos ácidos graxos saturados. As condições recomendadas para o processo foram o emprego de hexano como solvente, na proporção de 40% em relação à massa de óleo, e sem o emprego de agitação no segundo estágio do resfriamento. Sob tais condições, obteve-se um óleo com teor de ácidos graxos poli-insaturados (PUFA de 64,3%, sendo observado um aumento no percentual dos ácidos graxos insaturados de aproximadamente 9,2% e uma redução de 13,4% dos saturados, em relação ao óleo branqueado de pescado.The process of winterization consists of fractional crystallization, in which the triglycerides of oils and fats are separate by the partial crystallization in the liquid phase. The objective of this work was to evaluate significant variables and the operational conditions in the solvent winterization process of the fish oil. The crude fish oil from fishery industries was bleached and used as raw material. During the winterization step, the bleached oil was cooled progressively from 30 ºC to 5 ºC in three phases. The solvent

Direct Measurements of Island Growth and Step-Edge Barriers in Colloidal Epitaxy

KAUST Repository

Ganapathy, R.; Buckley, M. R.; Gerbode, S. J.; Cohen, I.

2010-01-01

-scale particles into microstructures that have numerous technological applications. To determine whether atomic epitaxial growth laws are applicable to the epitaxy of larger particles with attractive interactions, we investigated the nucleation and growth dynamics

Louis Althusser, Leo Strauss, and Democratic Leadership

OpenAIRE

Tamulis, Bron Cohen

2014-01-01

In taking up the topic of political leadership, I seek to analyze the legacy of social science in light of the sobering political events of the twentieth century. This dissertation is a composite study of the work of two philosophers, and, specifically, what they endeavored to accomplish by thinking and writing on the subject of politics. I concentrated on the post-War landscape, and the philosophers Louis Althusser and Leo Strauss, in order to analyze the way in which the figure of Machiav...

El fin del petróleo

OpenAIRE

Fontaine, Guillaume

2007-01-01

En el momento en que los demócratas de los Estados Unidos han encabezado, al parecer, la cruzada mundial contra el cambio climático, quizá no es inútil leer (o releer) el ensayo del periodista Paul Roberts, publicado a finales del 2004 bajo el título llamativo de "El fin del petróleo". En efecto, cuando se reactivan las recetas del "charity business" (como eran los megaconciertos contra la hambruna y la sequía en Somalia, o para la liberación de Mandela) para salvar nuestro planeta, y m...

Growth of epitaxial thin films by pulsed laser ablation

International Nuclear Information System (INIS)

Lowndes, D.H.

1992-01-01

High-quality, high-temperature superconductor (HTSc) films can be grown by the pulsed laser ablation (PLA) process. This article provides a detailed introduction to the advantages and curent limitations of PLA for epitaxial film growth. Emphasis is placed on experimental methods and on exploitation of PLA to control epitaxial growth at either the unit cell or the atomic-layer level. Examples are taken from recent HTSc film growth. 33 figs, 127 refs

Electrodeposition of epitaxial CdSe on (111) gallium arsenide

Energy Technology Data Exchange (ETDEWEB)

Cachet, H.; Cortes, R.; Froment, M. [Universite Pierre et Marie Curie, Paris (France). Phys. des Liquides et Electrochimie; Etcheberry, A. [Institut Lavoisier (IREM) UMR CNRS C0173, Universite de Versailles- St Quentin en Yvelynes, 45 Avenue des Etats Unis, 78035, Versailles (France)

2000-02-21

Epitaxial growth of CdSe has been achieved on GaAs(111) by electrodeposition from an aqueous electrolyte. The structure of the film corresponds to the cubic modification of CdSe. The quality of epitaxy has been investigated by reflection high energy electron diffraction, transmission electron microscopy and X-ray diffraction techniques. By XPS measurements the chemistry of the CdSe/GaAs interface and the composition of CdSe are determined. (orig.)

Geopolítica y petróleo. La nueva dependencia energética

OpenAIRE

Zeraoui, Zidane

2010-01-01

Este artículo, sobre geopolítica y petróleo, busca analizar la actual geopolítica internacional en función de la variable petrolera. Con el alza del precio del crudo a casi US $150 el barril, el “oro negro” se ha convertido más que nunca en un instrumento de poder global. Por otra parte, la demanda cada vez más apremiante de petróleo, por China e India, está empujando no solamente el precio de los hidrocarburos, sino también la pugna por el control de los yacimientos a nivel mundial o por lo ...

Epitaxial graphene-encapsulated surface reconstruction of Ge(110)

Science.gov (United States)

Campbell, Gavin P.; Kiraly, Brian; Jacobberger, Robert M.; Mannix, Andrew J.; Arnold, Michael S.; Hersam, Mark C.; Guisinger, Nathan P.; Bedzyk, Michael J.

2018-04-01

Understanding and engineering the properties of crystalline surfaces has been critical in achieving functional electronics at the nanoscale. Employing scanning tunneling microscopy, surface x-ray diffraction, and high-resolution x-ray reflectivity experiments, we present a thorough study of epitaxial graphene (EG)/Ge(110) and report a Ge(110) "6 × 2" reconstruction stabilized by the presence of epitaxial graphene unseen in group-IV semiconductor surfaces. X-ray studies reveal that graphene resides atop the surface reconstruction with a 0.34 nm van der Waals (vdW) gap and provides protection from ambient degradation.

Liquid epitaxy of Gasub(1-x)Alsub(x)Sb varizone structures

International Nuclear Information System (INIS)

Dedegkaev, T.T.; Kryukov, I.I.; Lidejkis, T.P.; Tsarenkov, B.V.; Yakovlev, Yu.P.

1980-01-01

To produce Gasub (1-x)Alsub(x)Sb varizon structures with preset limits for the change of the width of Eg forbidden zone and preset Eg gradient value and sign, epitaxy growth from the liquid phase of solid solutions of GaSb-AlSb system was investigated. The epitaxy was realized in two ways: by cooling the saturated solution of Ga-Al-Sb melt and using the isometric contineous mixing of two solution-melts with different Al content. As a result it was ascertained that: 1 the epitaxy by cooling a solution-melt permitted to produce Gasub(1-x)Alsub(x)Sb varizon structures only with small Eg gradients (<=30eV/cm); 2 the epitaxy by contineously mixing the solution-melts permitted to produce Gasub(1-x)Alsub(x)Sb varizon structures with increasing and decreasing Eg in the direction of layer growth in the whole interval of compositions. Eg gradient can be as great as thousands of eV/cm

The origin of local strain in highly epitaxial oxide thin films.

Science.gov (United States)

Ma, Chunrui; Liu, Ming; Chen, Chonglin; Lin, Yuan; Li, Yanrong; Horwitz, J S; Jiang, Jiechao; Meletis, E I; Zhang, Qingyu

2013-10-31

The ability to control the microstructures and physical properties of hetero-epitaxial functional oxide thin films and artificial structures is a long-sought goal in functional materials research. Normally, only the lattice misfit between the film and the substrate is considered to govern the physical properties of the epitaxial films. In fact, the mismatch of film unit cell arrangement and the Surface-Step-Terrace (SST) dimension of the substrate, named as "SST residual matching", is another key factor that significantly influence the properties of the epitaxial film. The nature of strong local strain induced from both lattice mismatch and the SST residual matching on ferroelectric (Ba,Sr)TiO3 and ferromagnetic (La,Ca)MnO3 thin films are systematically investigated and it is demonstrated that this combined effect has a dramatic impact on the physical properties of highly epitaxial oxide thin films. A giant anomalous magnetoresistance effect (~10(10)) was achieved from the as-designed vicinal surfaces.

Crescimento vegetativo e produção de óleo essencial de hortelã‑pimenta cultivada sob malhas

Directory of Open Access Journals (Sweden)

Andressa Giovannini Costa

2012-04-01

Full Text Available O objetivo deste trabalho foi avaliar o crescimento vegetativo e o teor, o rendimento e a composição química do óleo essencial de hortelã‑pimenta (Mentha piperita cultivada sob diferentes malhas, no Município de Lavras, MG. As mudas de hortelã‑pimenta foram cultivadas em cinco ambientes: pleno sol, malha preta, malha aluminizada, malha azul e malha vermelha, todas com 50% de irradiância. Utilizou-se o delineamento experimental inteiramente casualizado, com quatro repetições e cinco plantas por parcela. Foram avaliados os parâmetros: crescimento vegetativo, teor, rendimento e análise química do óleo essencial. Plantas de hortelã‑pimenta cultivadas em pleno sol e sob malhas preta e vermelha produziram maior biomassa seca de folhas e maiores teores e rendimentos do óleo essencial. Entretanto, a pleno sol, o óleo essencial das plantas apresentou maior teor de mentol e, sob as malhas preta e azul, de mentofurano. Portanto, é possível manipular o crescimento das plantas e a produção e a composição química do óleo essencial de hortelã‑pimenta mediante o cultivo sob malhas ou pleno sol.

Tempo de destilação e perfil volátil do óleo essencial de aroeira da praia (Schinus terebinthifolius) em Sergipe

OpenAIRE

Oliveira, L.F.M.; Oliveira Jr, L.F.G.; Santos, M.C.; Narain, N.; Leite Neta, M.T.S.

2014-01-01

Aos frutos e óleos essenciais da aroeira da praia (Schinus terebinthifolius) atribui-se atividade antimicrobiana sobre bactérias gram positivas além de ação anti-inflamatória. O óleo essencial da aroeira é utilizado no tratamento de micoses, sendo a sua atividade antifúngica atribuída à alta concentração de monoterpenos. Este estudo teve como objetivo determinar o melhor rendimento de destilação de óleo essencial de sementes e folhas da aroeira e os componentes químicos do óleo essencial nos ...

Nanoselective area growth of GaN by metalorganic vapor phase epitaxy on 4H-SiC using epitaxial graphene as a mask

International Nuclear Information System (INIS)

Puybaret, Renaud; Jordan, Matthew B.; Voss, Paul L.; Ougazzaden, Abdallah; Patriarche, Gilles; Sundaram, Suresh; El Gmili, Youssef; Salvestrini, Jean-Paul; Heer, Walt A. de; Berger, Claire

2016-01-01

We report the growth of high-quality triangular GaN nanomesas, 30-nm thick, on the C-face of 4H-SiC using nanoselective area growth (NSAG) with patterned epitaxial graphene grown on SiC as an embedded mask. NSAG alleviates the problems of defects in heteroepitaxy, and the high mobility graphene film could readily provide the back low-dissipative electrode in GaN-based optoelectronic devices. A 5–8 graphene-layer film is first grown on the C-face of 4H-SiC by confinement-controlled sublimation of silicon carbide. Graphene is then patterned and arrays of 75-nm-wide openings are etched in graphene revealing the SiC substrate. A 30-nm-thick GaN is subsequently grown by metal organic vapor phase epitaxy. GaN nanomesas grow epitaxially with perfect selectivity on SiC, in the openings patterned through graphene. The up-or-down orientation of the mesas on SiC, their triangular faceting, and cross-sectional scanning transmission electron microscopy show that they are biphasic. The core is a zinc blende monocrystal surrounded with single-crystal wurtzite. The GaN crystalline nanomesas have no threading dislocations or V-pits. This NSAG process potentially leads to integration of high-quality III-nitrides on the wafer scalable epitaxial graphene/silicon carbide platform.

Nanoselective area growth of GaN by metalorganic vapor phase epitaxy on 4H-SiC using epitaxial graphene as a mask

Energy Technology Data Exchange (ETDEWEB)

Puybaret, Renaud; Jordan, Matthew B.; Voss, Paul L.; Ougazzaden, Abdallah, E-mail: aougazza@georgiatech-metz.fr [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); CNRS UMI 2958, Georgia Institute of Technology, 2 Rue Marconi, 57070 Metz (France); Patriarche, Gilles [CNRS, Laboratoire de Photonique et de Nanostructures, Route de Nozay, 91460 Marcoussis (France); Sundaram, Suresh; El Gmili, Youssef [CNRS UMI 2958, Georgia Institute of Technology, 2 Rue Marconi, 57070 Metz (France); Salvestrini, Jean-Paul [Université de Lorraine, CentraleSupélec, LMOPS, EA4423, 57070 Metz (France); Heer, Walt A. de [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Berger, Claire [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); CNRS, Institut Néel, BP166, 38042 Grenoble Cedex 9 (France)

2016-03-07

We report the growth of high-quality triangular GaN nanomesas, 30-nm thick, on the C-face of 4H-SiC using nanoselective area growth (NSAG) with patterned epitaxial graphene grown on SiC as an embedded mask. NSAG alleviates the problems of defects in heteroepitaxy, and the high mobility graphene film could readily provide the back low-dissipative electrode in GaN-based optoelectronic devices. A 5–8 graphene-layer film is first grown on the C-face of 4H-SiC by confinement-controlled sublimation of silicon carbide. Graphene is then patterned and arrays of 75-nm-wide openings are etched in graphene revealing the SiC substrate. A 30-nm-thick GaN is subsequently grown by metal organic vapor phase epitaxy. GaN nanomesas grow epitaxially with perfect selectivity on SiC, in the openings patterned through graphene. The up-or-down orientation of the mesas on SiC, their triangular faceting, and cross-sectional scanning transmission electron microscopy show that they are biphasic. The core is a zinc blende monocrystal surrounded with single-crystal wurtzite. The GaN crystalline nanomesas have no threading dislocations or V-pits. This NSAG process potentially leads to integration of high-quality III-nitrides on the wafer scalable epitaxial graphene/silicon carbide platform.

Bioestímulo e bioaumento na remediação de solo contaminado com óleo lubrificante usado escala piloto

OpenAIRE

Graciane Silva

2010-01-01

O óleo lubrificante mineral é amplamente utilizado no cenário mundial no funcionamento de máquinas e motores. No entanto, o ciclo de vida deste petro-derivado resulta na geração de um resíduo (óleo lubrificante usado), o qual é nocivo ao meio ambiente quando não descartado adequadamente ou reciclado. No Brasil, apesar das normas que tratam especificamente do armazenamento, recolhimento e destino de óleo lubrificante usado, grande parte do mesmo ainda é despejado diretamente no meio ambiente, ...

Crescimento, esporulação e viabilidade de fungos entomopatogênicos em meios contendo diferentes concentrações do óleo de nim (Azadirachta indica

Directory of Open Access Journals (Sweden)

Marques Renata Paro

2004-01-01

Full Text Available A associação de extratos de origem vegetal com fungos entomopatogênicos pode aumentar a eficiência do controle biológico de pragas, reduzir custos e impactos ambientais. No presente trabalho, avaliou-se, através da concentração inibitória mínima, o efeito do óleo de nim (NIM-I-GO sobre o crescimento, esporulação e viabilidade de Metarhizium anisopliae, Beauveria bassiana e Paecilomyces farinosus. Utilizou-se o meio BDA, contendo diferentes concentrações de óleo de nim (C1: 5% de óleo de nim, e sucessivamente concentrações iguais a fraction one-half da concentração anterior, até C11: 0,0048% de óleo de nim. O óleo de nim reduziu o crescimento de colônias de B. bassiana e P. farinosus, que não diferiram significativamente do controle apenas na concentração C11, mas para M. anisopliae o mesmo efeito foi observado com 0,039% de óleo de nim (C8. A esporulação também foi significativamente reduzida pelo óleo de nim, exceto na concentração C11 para B. bassiana; contudo, não se verificou efeito do óleo na viabilidade de esporos dos fungos.

The physics of epitaxial graphene on SiC(0001)

International Nuclear Information System (INIS)

Kageshima, H; Hibino, H; Tanabe, S

2012-01-01

Various physical properties of epitaxial graphene grown on SiC(0001) are studied. First, the electronic transport in epitaxial bilayer graphene on SiC(0001) and quasi-free-standing bilayer graphene on SiC(0001) is investigated. The dependences of the resistance and the polarity of the Hall resistance at zero gate voltage on the top-gate voltage show that the carrier types are electron and hole, respectively. The mobility evaluated at various carrier densities indicates that the quasi-free-standing bilayer graphene shows higher mobility than the epitaxial bilayer graphene when they are compared at the same carrier density. The difference in mobility is thought to come from the domain size of the graphene sheet formed. To clarify a guiding principle for controlling graphene quality, the mechanism of epitaxial graphene growth is also studied theoretically. It is found that a new graphene sheet grows from the interface between the old graphene sheets and the SiC substrate. Further studies on the energetics reveal the importance of the role of the step on the SiC surface. A first-principles calculation unequivocally shows that the C prefers to release from the step edge and to aggregate as graphene nuclei along the step edge rather than be left on the terrace. It is also shown that the edges of the existing graphene more preferentially absorb the isolated C atoms. For some annealing conditions, experiments can also provide graphene islands on SiC(0001) surfaces. The atomic structures are studied theoretically together with their growth mechanism. The proposed embedded island structures actually act as a graphene island electronically, and those with zigzag edges have a magnetoelectric effect. Finally, the thermoelectric properties of graphene are theoretically examined. The results indicate that reducing the carrier scattering suppresses the thermoelectric power and enhances the thermoelectric figure of merit. The fine control of the Fermi energy position is thought to

ALFALFA DISCOVERY OF THE NEARBY GAS-RICH DWARF GALAXY LEO P. III. AN EXTREMELY METAL DEFICIENT GALAXY

Energy Technology Data Exchange (ETDEWEB)

Skillman, Evan D.; Berg, Danielle A.; Olive, Keith A.; McQuinn, Kristen B. W., E-mail: skillman@astro.umn.edu, E-mail: berg@astro.umn.edu, E-mail: olive@physics.umn.edu, E-mail: kmcquinn@astro.umn.edu [Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota, 116 Church St. SE, Minneapolis, MN 55455 (United States); and others

2013-07-01

We present KPNO 4 m and LBT/MODS spectroscopic observations of an H II region in the nearby dwarf irregular galaxy Leo P discovered recently in the Arecibo ALFALFA survey. In both observations, we are able to accurately measure the temperature sensitive [O III] {lambda}4363 line and determine a ''direct'' oxygen abundance of 12 + log(O/H) = 7.17 {+-} 0.04. Thus, Leo P is an extremely metal deficient (XMD) galaxy, and, indeed, one of the most metal deficient star-forming galaxies ever observed. For its estimated luminosity, Leo P is consistent with the relationship between luminosity and oxygen abundance seen in nearby dwarf galaxies. Leo P shows normal {alpha} element abundance ratios (Ne/O, S/O, and Ar/O) when compared to other XMD galaxies, but elevated N/O, consistent with the ''delayed release'' hypothesis for N/O abundances. We derive a helium mass fraction of 0.2509{sup +0.0184}{sub -0.0123}, which compares well with the WMAP + BBN prediction of 0.2483 {+-} 0.0002 for the primordial helium abundance. We suggest that surveys of very low mass galaxies compete well with emission line galaxy surveys for finding XMD galaxies. It is possible that XMD galaxies may be divided into two classes: the relatively rare XMD emission line galaxies which are associated with starbursts triggered by infall of low-metallicity gas and the more common, relatively quiescent XMD galaxies like Leo P, with very low chemical abundances due to their intrinsically small masses.

Composição química e concentração mínima bactericida de dezesseis óleos essenciais sobre Escherichia coli enterotoxigênica

Directory of Open Access Journals (Sweden)

A.A. SOUZA

2016-03-01

Full Text Available RESUMO Este trabalho teve por objetivo avaliar o efeito bactericida in vitro de dezesseis óleos essenciais sobre Escherichia coli enterotoxigênica (ETEC. Dentre os óleos essenciais estudados, três foram extraídos in situ por arraste a vapor e treze foram adquiridos comercialmente. Todos os óleos foram analisados por CG-EM e CG-DIC. A atividade bactericida foi avaliada pelo método de microdiluição utilizando-se caldo triptona de soja e microplacas de poliestireno de 96 poços, com posterior plaqueamento das culturas em ágar triptona de soja. Os óleos essenciais de Cinnamomum cassia e de Thymus vulgaris apresentaram concentração mínima bactericida (CMB de 0,12% e 0,25%, respectivamente. Já os óleos comerciais de Syzygium aromaticum e Origanum vulgare apresentaram ambos CMB de 0,50% e os óleos extraídos in situ de Cymbopogon citratus e Origanum vulgare apresentaram ambos CMB de 1,00%. Os dezesseis óleos essenciais apresentaram composição química qualitativa e quantitativa distintas. As análises químicas dos óleos essenciais de Cinnamomum cassia e de Thymus vulgaris tiveram a presença majoritária de E-cinamaldeído (84,52% e timol (50,89%. Conclui-se que os óleos de C. cassia e T. vulgaris foram os mais eficazes na inibição do crescimento in vitro dessa bactéria, a qual possui diferentes níveis de sensibilidade dependendo da composição química do óleo.

Factores de riesgo asociados a íleo posquirúrgico prolongado en pacientes sometidos a resección electiva de colon

Directory of Open Access Journals (Sweden)

M.A. Juárez-Parra

2015-10-01

Conclusiones: La presencia de estos factores de riesgo pueden servir como alertas para un seguimiento más cercano en pacientes de alto riesgo de íleo postoperatorio. El uso de anestesia peridural pudiera disminuir la incidencia de íleo.

On the density of states of disordered epitaxial graphene

International Nuclear Information System (INIS)

Davydov, S. Yu.

2015-01-01

The study is concerned with two types of disordered epitaxial graphene: (i) graphene with randomly located carbon vacancies and (ii) structurally amorphous graphene. The former type is considered in the coherent potential approximation, and for the latter type, a model of the density of states is proposed. The effects of two types of substrates, specifically, metal and semiconductor substrates are taken into account. The specific features of the density of states of epitaxial graphene at the Dirac point and the edges of the continuous spectrum are analyzed. It is shown that vacancies in epitaxial graphene formed on the metal substrate bring about logarithmic nulling of the density of states of graphene at the Dirac point and the edges of the continuous spectrum. If the Dirac point corresponds to the middle of the band gap of the semiconductor substrate, the linear trend of the density of states to zero in the vicinity of the Dirac point in defect-free graphene transforms into a logarithmic decrease in the presence of vacancies. In both cases, the graphene-substrate interaction is assumed to be weak (quasi-free graphene). In the study of amorphous epitaxial graphene, a simple model of free amorphous graphene is proposed as the initial model, in which account is taken of the nonzero density of states at the Dirac point, and then the interaction of the graphene sheet with the substrate is taken into consideration. It is shown that, near the Dirac point, the quadratic behavior of the density of states of free amorphous graphene transforms into a linear dependence for amorphous epitaxial graphene. In the study, the density of states of free graphene corresponds to the low-energy approximation of the electron spectrum

Atividade inseticida do óleo essencial de Hyptis marrubioides no controle de Zabrotes subfasciatus (Coleoptera, Chrysomelidae, Bruchinae

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Marcelo Barboza de Mello

2014-02-01

Full Text Available Sabe-se que uma grande porcentagem da produção e do armazenamento dos grãos de feijão é perdida pelo consumo de insetos. Este trabalho teve como objetivo avaliar a atividade inseticida do óleo essencial de Hyptis marrubioides no controle de Zabrotes subfasciatus. A extração do óleo essencial foi realizada pelo método de hidrodestilação em aparelho de Clevenger, por uma hora e meia e o ensaio biológico foi conduzido no Laboratório de Microscopia/IFSULDEMINAS, Campus Muzambinho. O delineamento experimental utilizado foi inteiramente casualizado, constituído de cinco concentrações de óleo essencial (0,0; 6,25%; 12,5%; 25% e 50%, com quatro repetições contendo um casal de Z. subfasciatus por repetição. Realizou-se o teste de mortalidade e inibição de oviposição. Utilizou-se três grãos de feijão tratados com 5 microlitros (μL de solução e três não tratados, caracterizando assim um teste com chance de escolha. Como controle, utilizou-se 100 μL de álcool 70%. Após a aplicação dos tratamentos, observou-se a reação dos indivíduos de Z. subfasciatus, evidenciando que os Tempos Letais (TL diminuem conforme há um aumento e contato direto dos insetos com as concentrações do óleo essencial de H. marrubioides. A aplicação do óleo essencial foi bastante efetiva, pois ocorreu mortalidade total dos insetos adultos e nenhuma oviposição. O intervalo de tempo de 28 minutos foi suficiente para provocar mortalidade de todos os indivíduos. Foi possível observar que o óleo essencial de H. marrubioides possui efeito inseticida sobre Z. subfasciatus, podendo auxiliar no manejo integrado de Z. subfasciatus em feijão armazenado.

Alfalfa discovery of the nearby gas-rich dwarf galaxy LEO P. V. Neutral gas dynamics and kinematics

International Nuclear Information System (INIS)

Bernstein-Cooper, Elijah Z.; Pardy, Stephen A.; Cannon, John M.

2014-01-01

We present new H I spectral line imaging of the extremely metal-poor, star-forming dwarf irregular galaxy Leo P. Our H I images probe the global neutral gas properties and the local conditions of the interstellar medium (ISM). The H I morphology is slightly elongated along the optical major axis. We do not find obvious signatures of interaction or infalling gas at large spatial scales. The neutral gas disk shows obvious rotation, although the velocity dispersion is comparable to the rotation velocity. The rotation amplitude is estimated to be V c =15 ± 5 km s –1 . Within the H I radius probed by these observations, the mass ratio of gas to stars is roughly 2:1, while the ratio of the total mass to the baryonic mass is ≳15:1. We use this information to place Leo P on the baryonic Tully-Fisher relation, testing the baryonic content of cosmic structures in a sparsely populated portion of parameter space that has hitherto been occupied primarily by dwarf spheroidal galaxies. We detect the signature of two temperature components in the neutral ISM of Leo P; the cold and warm components have characteristic velocity widths of 4.2 ± 0.9 km s –1 and 10.1 ± 1.2 km s –1 , corresponding to kinetic temperature upper limits of ∼1100 K and ∼6200 K, respectively. The cold H I component is unresolved at a physical resolution of 200 pc. The highest H I surface densities are observed in close physical proximity to the single H II region. A comparison of the neutral gas properties of Leo P with other extremely metal-deficient (XMD) galaxies reveals that Leo P has the lowest neutral gas mass of any known XMD, and that the dynamical mass of Leo P is more than two orders of magnitude smaller than any known XMD with comparable metallicity.

Alfalfa discovery of the nearby gas-rich dwarf galaxy LEO P. V. Neutral gas dynamics and kinematics

Energy Technology Data Exchange (ETDEWEB)

Bernstein-Cooper, Elijah Z.; Pardy, Stephen A. [Department of Astronomy, University of Wisconsin, 475 N Charter Street, Madison, WI 53706 (United States); Cannon, John M., E-mail: ezbc@astro.wisc.edu, E-mail: spardy@astro.wisc.edu, E-mail: jcannon@macalester.edu [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); and others

2014-08-01

We present new H I spectral line imaging of the extremely metal-poor, star-forming dwarf irregular galaxy Leo P. Our H I images probe the global neutral gas properties and the local conditions of the interstellar medium (ISM). The H I morphology is slightly elongated along the optical major axis. We do not find obvious signatures of interaction or infalling gas at large spatial scales. The neutral gas disk shows obvious rotation, although the velocity dispersion is comparable to the rotation velocity. The rotation amplitude is estimated to be V {sub c} =15 ± 5 km s{sup –1}. Within the H I radius probed by these observations, the mass ratio of gas to stars is roughly 2:1, while the ratio of the total mass to the baryonic mass is ≳15:1. We use this information to place Leo P on the baryonic Tully-Fisher relation, testing the baryonic content of cosmic structures in a sparsely populated portion of parameter space that has hitherto been occupied primarily by dwarf spheroidal galaxies. We detect the signature of two temperature components in the neutral ISM of Leo P; the cold and warm components have characteristic velocity widths of 4.2 ± 0.9 km s{sup –1} and 10.1 ± 1.2 km s{sup –1}, corresponding to kinetic temperature upper limits of ∼1100 K and ∼6200 K, respectively. The cold H I component is unresolved at a physical resolution of 200 pc. The highest H I surface densities are observed in close physical proximity to the single H II region. A comparison of the neutral gas properties of Leo P with other extremely metal-deficient (XMD) galaxies reveals that Leo P has the lowest neutral gas mass of any known XMD, and that the dynamical mass of Leo P is more than two orders of magnitude smaller than any known XMD with comparable metallicity.

Actividade antimicrobiana do óleo essencial do Foeniculum vulgare Miller Antimicrobial activity of Foeniculum vulgare Miller essential oil

Directory of Open Access Journals (Sweden)

M. T. Tinoco

2007-01-01

Full Text Available O Foeniculum vulgare Mill. subsp. vulgare é uma planta espontânea da região mediterrânea, pertencente à família Apiaceae. O seu óleo essencial, principalmente o dos frutos secos, é amplamente utilizado nas indústrias alimentar, farmacêutica, cosmética e perfumaria. Neste trabalho, pretendeu-se avaliar a actividade antimicrobiana do óleo essencial dos frutos verdes e das folhas da variedade de funcho doce colhido no Alentejo, na região de Évora, e relacionar essa actividade com a respectiva composição química. A extracção dos óleos essenciais foi efectuada por hidrodestilação e a sua análise foi feita por GC-FID e GC-MS. No óleo das folhas foram identificados como componentes maioritários os fenilpropanóides anetol, fenchona e estragol e o monoterpeno a-felandreno, enquanto que o óleo dos frutos apresentou como constituintes predominantes anetol e fenchona. A actividade antimicrobiana dos óleos foi avaliada face às estirpes Staphylococcus aureus, Escherichia coli, Saccharomyces spp., Fusarium oxysporum e Penicillium sp.. Os óleos essenciais apresentaram actividade antimicrobiana contra S. aureus, Saccharomyces spp. e Fusarium oxysporum.Foeniculum vulgare Mill. ssp. vulgare is a spontaneous plant of Mediterranean region that belongs to the Apiaceae family. Its essential oil is used as additives in food, pharmaceutical, cosmetic and perfume industries mainly that one obtained from dried seeds. The main goal of this work were to evaluate the antimicrobial activity of essential oils obtained from fresh leaves and unripe seeds of sweet fennel, collected in Évora-Alentejo, in face of their chemical composition. The extraction of the essentials oils was made by hydrodistillation. Chemical analyses were carried out by GC-FID and GCMS. Phenylpropanoides anethole, fenchone, estragole and the monoterpene aphellandrene were the most abundant compounds of leaves essential oil. Seeds essential oil showed as main components

Leo Tolstoy's theory of sleep.

Science.gov (United States)

Vein, Alla A

2008-03-01

Throughout his life, Leo Tolstoy was fascinated by the phenomena of sleep and dreams. He composed a series of observations and judgements that were brought together under "my theory of sleep". Tolstoy was constantly preoccupied with the basic principles of "the theory". It is hard to name a work by him where a description of sleep and/or a dream does not play a vital role in the unfolding of the plot. They testify to Tolstoy's interest in the mechanism of sleep and in the processes of falling asleep and waking up. Tolstoy viewed sleep as a specific state of consciousness, and he subsequently linked the concept of sleep with the concept of death. For him sleep and awakening were experiences emblematic of life and death.

Controllable factors affecting the epitaxial quality of LaCoO3 films ...

Indian Academy of Sciences (India)

2018-03-23

Mar 23, 2018 ... ... larger molecular weight contribute to the improvement of epitaxial quality of LaCoO3 epitaxial film. ..... Research Fund of Education Department of Sichuan Province. (grant nos. 16ZA0133 and 15ZB0108); and the Doctoral.

Triagem de métodos de purificação de óleos com acidez elevada para produção de biodiesel

OpenAIRE

Daniel Grabauskas

2013-01-01

O presente estudo teve como objetivo selecionar procedimentos de purificação de óleos vegetais, com enfoque na desacidificação, comparando a eficiência de métodos de refino alternativos (adsorção e extração liquido-liquido) com o convencional (alcalino). Para tanto, foram utilizados óleos com baixo impacto na cadeia alimentícia, como óleo de andíroba e óleo de macaúba, visando contribuir para a ampliação de matérias-primas lipídicas na produção de biodiesel. A triagem do método de purificação...

Selfsupported epitaxial silicon films

International Nuclear Information System (INIS)

Lazarovici, D.; Popescu, A.

1975-01-01

The methods of removing the p or p + support of an n-type epitaxial silicon layer using electrochemical etching are described. So far, only n + -n junctions have been processed. The condition of anodic dissolution for some values of the support and layer resistivity are given. By this method very thin single crystal selfsupported targets of convenient areas can be obtained for channeling - blocking experiments

Oral subcutaneous midline leiomyomatous hamartoma presenting as congenital incisive papilla overgrowth in a toddler

Directory of Open Access Journals (Sweden)

Ashish Loomba

2017-01-01

Full Text Available Congenital soft-tissue tumors of oral cavity are mostly hyperplastic and benign in nature. This article presents an unusual case of congenital subcutaneous hamartoma of incisive papilla in a 2-year-old female child causing feeding and breathing difficulty. Total excisional biopsy was done under local anesthesia. Histopathology of tissue in reticulin-stained slide showed the presence of immature muscle fibers whereas Masson's trichrome stain revealed collagen fibers and smooth muscles confirming the diagnosis of oral midline subcutaneous smooth muscle (leiomyomatous hamartoma of incisive papilla. It is important for dental professionals to be aware of this oral lesion present from birth mimicking overgrowth of incisive papilla, by its presentation, differential diagnosis, histopathology, and management.

Essential oils for rust control on coffee plants Óleos essenciais no controle da ferrugem em cafeeiro

Directory of Open Access Journals (Sweden)

Ricardo Borges Pereira

2012-02-01

Full Text Available Rust is considered the most important disease in coffee because it causes severe defoliation in plants and, consequently, reduction in productivity. This study evaluated the in vitro effect of essential oils of cinnamon, citronella, lemongrass, clove, tea tree, thyme, neem and eucalyptus on the germination of urediniospores of Hemileia vastatrix; the effectiveness of these oils to control rust on seedlings of coffee cultivars Catucaí 2SL, Catuaí IAC 62 and Mundo Novo 379/19 in the greenhouse; and the effect of more promising oils on urediniospores of H. vastatrix by transmission electron microscopy (TEM. All the essential oils inhibited the germination of urediniospores with increasing concentrations. All oils promoted partial control of the disease in the greenhouse. However, the oils of thyme, clove and citronella, at a concentration of 1000 µL L-1, were most effective in controlling the disease on cultivars Catucaí 2SL, Catuaí IAC 62 and Mundo Novo 379/19, respectively. The images generated in TEM showed that urediniospores exposed to oils of clove, citronella and thyme promoted cellular disorganization and cytoplasmic vacuolization, which was more pronounced in urediniospores exposed to citronella oil. The oils of thyme, clove and citronella are promising for the control of rust in coffee.A ferrugem é considerada a doença de maior importância no cafeeiro, pois causa acentuada desfolha nas plantas e, consequentemente, redução na produtividade. Este trabalho avaliou o efeito in vitro de óleos essenciais de canela, citronela, capim-limão, cravo-da-índia, árvore-de-chá, tomilho, nim e eucalipto na germinação de urediniósporos de Hemileia vastatrix; a eficácia desses óleos no controle da ferrugem em mudas de cafeeiro das cultivares Catucaí 2SL, Catuaí IAC 62 e Mundo Novo 379/19 em casa de vegetação; e o efeito dos óleos mais promissores sobre urediniósporos de H. vastatrix por meio de microscopia eletrônica de transmiss

VARIABILITY AND STAR FORMATION IN LEO T, THE LOWEST LUMINOSITY STAR-FORMING GALAXY KNOWN TODAY

Energy Technology Data Exchange (ETDEWEB)

Clementini, Gisella; Cignoni, Michele; Ramos, Rodrigo Contreras; Federici, Luciana; Tosi, Monica [INAF, Osservatorio Astronomico di Bologna, I-40127 Bologna (Italy); Ripepi, Vincenzo; Marconi, Marcella; Musella, Ilaria, E-mail: gisella.clementini@oabo.inaf.it, E-mail: rodrigo.contreras@oabo.inaf.it, E-mail: luciana.federici@oabo.inaf.it, E-mail: monica.tosi@oabo.inaf.it, E-mail: michele.cignoni@unibo.it, E-mail: ripepi@na.astro.it, E-mail: marcella@na.astro.it, E-mail: ilaria@na.astro.it [INAF, Osservatorio Astronomico di Capodimonte, I-80131 Napoli (Italy)

2012-09-10

We present results from the first combined study of variable stars and star formation history (SFH) of the Milky Way 'ultra-faint' dwarf (UFD) galaxy Leo T, based on F606W and F814W multi-epoch archive observations obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. We have detected 14 variable stars in the galaxy. They include one fundamental-mode RR Lyrae star and 11 Anomalous Cepheids with periods shorter than 1 day, thus suggesting the occurrence of multiple star formation episodes in this UFD, of which one about 10 Gyr ago produced the RR Lyrae star. A new estimate of the distance to Leo T of 409{sup +29}{sub -27} kpc (distance modulus of 23.06 {+-} 0.15 mag) was derived from the galaxy's RR Lyrae star. Our V, V - I color-magnitude diagram (CMD) of Leo T reaches V {approx} 29 mag and shows features typical of a galaxy in transition between dwarf irregular and dwarf spheroidal types. A quantitative analysis of the SFH, based on the comparison of the observed V, V - I CMD with the expected distribution of stars for different evolutionary scenarios, confirms that Leo T has a complex SFH dominated by two enhanced periods about 1.5 and 9 Gyr ago, respectively. The distribution of stars and gas shows that the galaxy has a fairly asymmetric structure.

Estimation of the lion ( Panthera leo ) population in the southwestern ...

African Journals Online (AJOL)

A previous estimate of the lion (Panthera leo) population in the southwestern Kgalagadi Transfrontier Park (KTP) was made over 20 years ago. This together with increased fears regarding the viability of the population as a result of recent killings of roaming animals, an observed increase in non-violent mortalities during ...

Ion beam deposited epitaxial thin silicon films

International Nuclear Information System (INIS)

Orrman-Rossiter, K.G.; Al-Bayati, A.H.; Armour, D.G.; Donnelly, S.E.; Berg, J.A. van den

1991-01-01

Deposition of thin films using low energy, mass-separated ion beams is a potentially important low temperature method of producing epitaxial layers. In these experiments silicon films were grown on Si (001) substrates using 10-200 eV 28 Si + and 30 Si + ions at substrate temperatures in the range 273-1073 K, under ultrahigh-vacuum conditions (deposition pressure -7 Pa). The film crystallinity was assessed in situ using medium energy ion scattering (MEIS). Films of crystallinity comparable to bulk samples were grown using 10-40 eV 28 Si + and 30 Si + ions at deposition temperatures in the range 623-823 K. These experiments confirmed the role of key experimental parameters such as ion energy, substrate temperature during deposition, and the surface treatment prior to deposition. It was found that a high temperature in situ anneal (1350-1450 K) gave the best results for epitaxial nucleation, whereas low energy (20-40 eV) Cl + ion bombardment resulted in amorphous film growth. The deposition energy for good epitaxial growth indicates that it is necessary to provide enough energy to induce local mobility but not to cause atomic displacements leading to the buildup of stable defects, e.g. divacancies, below the surface layer of the growing film. (orig.)

Acción antimicrobiana de extracto etanólico de propóleos sobre estreptococos mutans

Directory of Open Access Journals (Sweden)

Patricia Alejandra Vaculik

2014-12-01

Full Text Available El propóleo es un producto natural, posee una amplia variedad de propiedades vinculadas a las ciencias de la salud. De acuerdo al lugar de origen, condiciones climatológicas y tipo de especies botánicas circundantes, son las características que va a reunir. Por ello la particularidad de conocer el tipo de propóleos de nuestra zona geográfica y las propiedades que posee de acuerdo a sus compuestos químicos. La caries dental es una enfermedad infecciosa, que se origina por la interacción de múltiples factores, la dieta, el diente susceptible, los microorganismos, tiempo y la edad. Entre los microorganismos implicados en la formación de caries encontramos al Estreptococos mutans. El objetivo de este trabajo es conocer el propóleo de nuestra región y sus efectos antimicrobianos sobre los Estreptococos mutans.

ANÁLISE DO IMPACTO DOS ROYALTIES DO PETRÓLEO NO DESENVOLVIMENTO LOCAL DOS MUNICÍPIOS POTIGUARES

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Ridalvo Medeiros Alves de Oliveira

2009-12-01

Full Text Available Os royalties do petróleo são compensações financeiras consequentes da exploração de petróleo ou gás natural. Devido à relevância da receita dos royalties do petróleo para a política fiscal e de desenvolvimento econômico do Rio Grande do Norte, e em particular, para os municípios que compõem a Área de Petróleo Potiguar, se fez necessário estabelecer um estudo sobre as suas influências na dinâmica socioeconômica dessa região. O objetivo geral desse artigo é investigar as contribuições das receitas extraordinárias, originadas da atividade industrial de petróleo no território potiguar, para a melhoria da qualidade de vida destes municípios. Assim, através da evolução dos índices de IDH-M vislumbrou-se observar se os royalties têm contribuído para o desenvolvimento humano nos municípios em estudo. Os dados para a pesquisa foram obtidos junto ao IBGE, ANP e FERMURN, e para analisar aevolução das duas variáveis – royalties e IDH-M – foi utilizada a metodologia descritiva. Ao final do artigo conclui-se que um dos fatores que ocasionaram na melhoria da dinâmica de desenvolvimento dos municípios da região foi o incremento dessa receita extraordinária nosorçamentos municipais, permitindo investimentos em programas que possibilitaram melhoria nas variáveis: renda, longevidade e educação. O resultado do coeficiente de Pearson (0,689apresentou que existe uma correlação positiva entre as variáveis no período de 1995 a 2000.

Epitaxial stabilization of ordered Pd–Fe structures on perovskite substrates

Energy Technology Data Exchange (ETDEWEB)

Harton, Renee M., E-mail: reneehar@umich.edu [Department of Physics, University of Michigan, 450 Church St., Ann Arbor, MI 48109 (United States); Stoica, Vladimir A. [Department of Materials Science and Engineering, Pennsylvania State University, 201 Old Main, University Park, PA 16802 (United States); Clarke, Roy [Department of Physics, University of Michigan, 450 Church St., Ann Arbor, MI 48109 (United States)

2017-05-01

We report the fabrication of epitaxial ferromagnetic Pd{sub 3}Fe thin films on SrTiO{sub 3}(001) substrates by promoting the interdiffusion of an Fe/Pd multilayer heterostructure using thermal annealing. Prior to annealing, the results of in-situ Reflection High-Energy Electron Diffraction characterization suggest that each Fe and Pd layer exhibited an in-plane epitaxial relationship with the SrTiO{sub 3}(001) substrate. X-Ray diffraction and magneto-optic Kerr effect characterization, conducted post-annealing, demonstrate that the film composition is majority Pd{sub 3}Fe and exhibits in-plane magnetization reversal with a moderate coercive field of ≈760 Oe. This demonstration of an ordered atomic layer heterostructure grown on a perovskite substrate suggests a route to epitaxial interfacial structures which can achieve strain-assisted magnetic switching.

Mid-Infrared Observations of Possible Intergalactic Star Forming Regions in the Leo Ring

Science.gov (United States)

Giroux, Mark; Smith, B.; Struck, C.

2011-05-01

Within the Leo group of galaxies lies a gigantic loop of intergalactic gas known as the Leo Ring. Not clearly associated with any particular galaxy, its origin remains uncertain. It may be a primordial intergalactic cloud alternatively, it may be a collision ring, or have a tidal origin. Combining archival Spitzer images of this structure with published UV and optical data, we investigate the mid-infrared properties of possible knots of star formation in the ring. These sources are very faint in the mid-infrared compared to star forming regions in the tidal features of interacting galaxies. This suggests they are either deficient in dust, or they may not be associated with the ring.

CONSISTÊNCIA DE MISTURA DE GORDURAS HIDROGENADAS E ÓLEO DE SOJA

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SIMÕES Ilka Sumiyoshi

1998-01-01

Full Text Available A consistência é um aspecto funcional importante das gorduras plásticas, que são misturas de cristais de gordura sólida e óleo líquido. A relação entre as duas fases e o caracter cristalino da fase sólida determinam a consistência e a firmeza das amostras. O objetivo do trabalho foi determinar a consistência de duas gorduras vegetais hidrogenadas e suas misturas binárias e ternárias, com a presença ou não de óleo de soja, a partir dos resultados do analisador de textura (TA XT2, variando as profundidades de penetração e o ângulo dos cones. Aplicou-se um modelo de regressão múltipla, do tipo cúbico especial para as misturas de óleo e gorduras, utilizando o aplicativo MIXPLOT para a construção de diagrama triangular. A força de compressão variou de 0,0080 a 5,459 kg, dependendo da amostra e da profundidade de penetração do cone. Para os cones de ângulos 30, 40 e 45º, as consistências foram todas estatisticamente semelhantes, a p< 0,05. Para algumas amostras, os resultados empregando o cone de 20º foram estatisticamente diferentes. Tais diferenças de resultados podem ser justificadas pelo fato da geometria do cone de 20º ser diferente, em função do truncamento de sua ponta. A análise do diagrama triangular mostra que o componente óleo de soja não contribuiu estatisticamente para a consistência. Os coeficientes relativos às interações foram sempre negativos, demonstrando efeito antagônico para a consistência, característico das interações eutéticas entre gorduras. Este efeito eutético ocorre devido à incompatibilidade no estado sólido entre os componentes da mistura.

EFEITO DA SECAGEM E DO ARMAZENAMENTO DAS SEMENTES DE PINHÃO-MANSO (Jatropha curcas L. NA QUALIDADE DO ÓLEO

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Leonnardo Cruvinel Furquim

2014-10-01

Full Text Available O objetivo do presente trabalho foi avaliar a influência da secagem e do armazenamento de sementes de pinhão-manso na qualidade do óleo produzido. O experimento de secagem foi realizado com 5 variações de temperatura: 30, 40, 50, 60 e 70 °C, até a umidade de 9,3 ± 1,1% de base seca. O experimento de armazenamento foi realizado variando-se a condição e armazenamento: Ambiente do Laboratório (26 ± 3 °C; 55 ± 12% UR, Câmara Refrigerada do tipo B.O.D. (5 ± 1 °C; 79 ± 5% UR e Câmara Climatizada com aparelho de ar condicionado (18 ± 1 °C; 53 ± 7% UR; e o tempo de armazenamento: 2 e 4 meses. Os óleos foram avalizados em teor de óleo e os índices de acidez, peróxido e iodo. A secagem das sementes proporcionou elevação considerável no potencial de rancificação em temperaturas maiores ou iguais a 30 °C, revelando que secagens à temperaturas menores recomendável. Os armazenamentos das sementes nas câmaras climatizadas e refrigeradas apresentaram perdas na qualidade do óleo, com alto potencial de rancificação e de hidrólise dos óleos, respectivamente, revelando que o armazenamento em condições naturais é a mais indicada na manutenção da qualidade do óleo de pinhão-manso.

Kinetic-energy induced smoothening and delay of epitaxial breakdown in pulsed-laser deposition

International Nuclear Information System (INIS)

Shin, Byungha; Aziz, Michael J.

2007-01-01

We have isolated the effect of kinetic energy of depositing species from the effect of flux pulsing during pulsed-laser deposition (PLD) on surface morphology evolution of Ge(001) homoepitaxy at low temperature (100 deg. C). Using a dual molecular beam epitaxy (MBE) PLD chamber, we compare morphology evolution from three different growth methods under identical experimental conditions except for the differing nature of the depositing flux: (a) PLD with average kinetic energy 300 eV (PLD-KE); (b) PLD with suppressed kinetic energy comparable to thermal evaporation energy (PLD-TH); and (c) MBE. The thicknesses at which epitaxial breakdown occurs are ranked in the order PLD-KE>MBE>PLD-TH; additionally, the surface is smoother in PLD-KE than in MBE. The surface roughness of the films grown by PLD-TH cannot be compared due to the early epitaxial breakdown. These results demonstrate convincingly that kinetic energy is more important than flux pulsing in the enhancement of epitaxial growth, i.e., the reduction in roughness and the delay of epitaxial breakdown

TOXICIDADE DE ÓLEOS ESSENCIAIS PARA O CONTROLE DE Tetranychus urticae KOCH, 1836 (ACARI: TETRANYCHIDAE)

OpenAIRE

Camila Santos Teixeira; Camila Costabeber Nunes; Romário Vargas; José Romário de Carvalho; Hugo Bolsoni Zago

2017-01-01

O ácaro rajado é considerado uma importante praga agrícola, causando danos em diferentes cultivos. O controle à base de acaricidas químicos pode vir a causar problemas ambientais e à saúde do homem. Desta forma o uso de óleos essenciais obtidos de produtos botânicos é uma alternativa no controle de pragas por apresentar baixo efeito residual, sendo objetivo deste trabalho avaliar a mortalidade e o efeito na fertilidade de fêmeas adultas de Tetranychus urticae submetidas a tratamentos com óleo...

Crystalline and electronic structure of epitaxial γ-Al2O3 films

International Nuclear Information System (INIS)

Wu, Huiyan; Lu, Dawei; Zhu, Kerong; Xu, Guoyong; Wang, Hu

2013-01-01

Epitaxial γ-Al 2 O 3 films were fabricated on SrTiO 3 (1 0 0) substrates using pulsed laser deposition (PLD) technique. The high quality of epitaxial growth γ-Al 2 O 3 films was confirmed by X-ray diffraction (XRD). Atomic force microscopy (AFM) images indicated the smooth surfaces and the step-flow growth of the films. In order to illuminate the electronic properties and the local structure of the epitaxial γ-Al 2 O 3 , we experimentally measured the X-ray absorption near-edge structure (XANES) spectrum at the O K-edge and compared the spectrum with the theoretical simulations by using various structure models. Our results based on XANES spectrum analysis indicated that the structure of the epitaxial γ-Al 2 O 3 film was a defective spinel with Al vacancies, which prefer to be located at the octahedral sites

Microstructure of epitaxial YBa2Cu3O7-x thin films grown on LaAlO3 (001)

International Nuclear Information System (INIS)

Hsieh, Y.; Siegal, M.P.; Hull, R.; Phillips, J.M.

1990-01-01

We report a microstructural investigation of the epitaxial growth of YBa 2 Cu 3 O 7-x (YBCO) thin films on LaAlO 3 (001) substrates using transmission electron microscopy (TEM). Epitaxial films grow with two distinct modes: c epitaxy (YBCO) single crystal with the c (axis normal to the surface and a epitaxy (YBCO) single crystal with the c axis in the interfacial plane), where c epitaxy is the dominant mode grown in all samples 35--200 nm thick. In 35 nm YBCO films annealed at 850 degree C, 97±1% of the surface area is covered by c epitaxy with embedded anisotropic a-epitaxial grains. Quantitative analysis reveals the effect of film thickness and annealing temperature on the density, grain sizes, areal coverages, and anisotropic growth of a epitaxy

Stent-assisted coiling of intracranial aneurysms using LEO stents: long-term follow-up in 153 patients.

Science.gov (United States)

Sedat, Jacques; Chau, Yves; Gaudart, Jean; Sachet, Marina; Beuil, Stephanie; Lonjon, Michel

2018-02-01

Coiling associated with placement of a self-expandable intracranial stent has improved the treatment of intracranial wide-necked aneurysms. Little is known, however, about the durability of this treatment. The purpose of this report is to present our experience with the LEO stent and to evaluate the complications, effectiveness, and long-term results of this technique. We analyzed the records of 155 intracranial unruptured aneurysms that were treated by stent-assisted coiling with a LEO stent between 2008 and 2012. Procedural, early post-procedural, and delayed complications were recorded. Clinical and angiographic follow-up of patients was conducted over a period of at least 36 months. No procedural mortality was observed. One-month morbidity was observed in 14 out of 153 patients (9,15%). One hundred thirty-eight patients (with 140 aneurysms) had clinical and angiographic follow-up for more than 36 months. No aneurysm rupture was observed during follow-up. Four patients presented an intra-stent stenosis at 8 months, and 6 patients who had an early recurrence were retreated. Final results showed 85% complete occlusion, 13% neck remnants, and 2% stable incomplete occlusion. Stent-assisted coiling with the LEO stent is a safe and effective treatment for unruptured intracranial aneurysms. The long-term clinical outcomes with the LEO stent are excellent with a high rate of complete occlusion that is stable over time.

Uso de Leersia hexandra (Poaceae) en la fitorremediación de suelos contaminados con petróleo fresco e intemperizado

OpenAIRE

Arias-Trinidad, Alfredo; Rivera-Cruz, María del Carmen; Roldán-Garrigós, Antonio; Aceves-Navarro, Lorenzo Armando; Quintero-Lizaola, Roberto; Hernández-Guzmán, Javier

2017-01-01

ResumenLa industria petrolera ha generado derrames crónicos de petróleo y su acumulación en Gleysoles en zonas anegadas en el estado de Tabasco, en el sureste de México. El anegamiento es un factor que limita el uso de tecnologías de remediación por el alto costo y los bajos niveles de degradación del petróleo, sin embargo, Leersia hexandra Sw. es un pasto que crece en estas zonas contaminadas con petróleo intemperizado. El objetivo del estudio fue evaluar la densidad de bacterias, producción...

Bioatividade de óleos essenciais no controle de Botrytis cinerea isolado de morangueiro Essential oils bioactivity in strawberry grey mould control

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E.R. Lorenzetti

2011-01-01

Full Text Available Objetivou-se avaliar o uso de óleos essenciais sobre isolados de Botrytis cinerea, causador do mofo cinzento em morangueiro. Foram testados óleos essenciais de capim-limão, palmarosa, citronela, cravo, canela, menta, lavanda, tangerina, eucalipto, melaleuca, alecrim e laranja, todos estes analisados em cromatógrafo a gás acoplado a detector de massas, para identificação dos principais componentes dos óleos. Foram avaliados o crescimento micelial, produção e germinação de conídios de B. cinerea, com a incorporação do óleo no meio de cultura. Realizou-se ainda uma avaliação de voláteis e a eficiência de óleos em isolado resistente a fungicida. Para cada teste, diferentes óleos apresentaram eficiência, contudo capim limão, palmarosa, canela e menta demonstraram os melhores efeitos em todos os testes realizados. Todos os tratamentos a base de óleos demonstraram efeito semelhante a um fungicida recomendado para a cultura, a base de tiofanato metílico. Dois tratamentos mostraram-se efetivos no caso de isolado resistente (óleo de capim limão e de canela. Óleos essenciais mostram-se como opção promissora para o desenvolvimento de possíveis produtos fitossanitários para o manejo de doenças em plantas.This study aimed evaluates essential oils in Botrytis cinerea isolates growth, which causes gray mould on strawberry. Were tested essential oils of lemon grass, palmrose, citronella, clove, cinnamon, mint, lavender, tangerine, eucalyptus, tea tree, rosemary and orange. The oils were analyzed in gas chromatograph attached to mass detector for identifying the mainly oils components. Were evaluated mycelial growth, conidia production and conidia germination of B. cinerea, with oil incorporation in culture medium. Were conducted an evaluation of oils volatile components and the efficiency of oils in fungicide-resistant isolate. For each test, different oils showed efficiency, however lemongrass, palmarosa, cinnamon and mint

Epitaxial ternary nitride thin films prepared by a chemical solution method

Energy Technology Data Exchange (ETDEWEB)

Luo, Hongmei [Los Alamos National Laboratory; Feldmann, David M [Los Alamos National Laboratory; Wang, Haiyan [TEXAS A& M; Bi, Zhenxing [TEXAS A& M

2008-01-01

It is indispensable to use thin films for many technological applications. This is the first report of epitaxial growth of ternary nitride AMN2 films. Epitaxial tetragonal SrTiN2 films have been successfully prepared by a chemical solution approach, polymer-assisted deposition. The structural, electrical, and optical properties of the films are also investigated.

O petróleo e a governança energética global: dilemas contemporâneos

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Enrique Carlos Natalino

2017-12-01

Full Text Available O artigo se propõe a analisar a problemática do petróleo e as suas múltiplas implicações para a governança global contemporânea. O petróleo é mais o estratégico insumo energético do planeta, capaz de levar as nações a alcançar a prosperidade ou até a conflitos armados. Seria possível pensar numa aproximação entre a gestão do petróleo na cena internacional e as discussões mais amplas acerca da concepção de espaços internacionais mais horizontais, participativos e democráticos? Nessa direção, o artigo busca investigar a trajetória do petróleo como commodity energética mundial e o seu impacto na economia e na política contemporâneas. A hipótese do trabalho é que a governança petrolífera mundial nas primeiras duas décadas do século XXI tem sido baseada não apenas em regras de mercado, nacionalismo e cálculos realistas de poder, mas em possibilidades efetivas de cooperação internacional e de ganhos mútuos.

Caracterização fitoquímica do óleo de soja adicionado de extrato de Portulaca oleracea L.

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Neuza Jorge

Full Text Available RESUMO Este trabalho teve como principais objetivos medir o teor de compostos fenólicos totais e a atividade antioxidante do extrato de Portulaca oleracea L., além de avaliar a estabilidade oxidativa e a retenção dos compostos fitoquímicos presentes no óleo de soja adicionado de antioxidantes sintéticos (TBHQ e BHT e naturais (Extrato de Portulaca oleracea L.. Os tratamentos: óleo de soja (OS, óleo de soja adicionado de 100 mg/kg TBHQ (TBHQ, óleo de soja adicionado de 100 mg/kg BHT (BHT e óleo de soja adicionado de 100 mg/kg extrato (Extrato foram submetidos à termoxidação a 180 oC, por cinco horas. O extrato apresentou 99,5 mg EAG/100 g de compostos fenólicos totais e 84,6%, 35,5% e 1,8 µM Trolox/100 g de atividade antioxidante para DPPH, sistema β-caroteno/ácido linoleico e FRAP, respectivamente. A estabilidade oxidativa do tratamento Extrato foi inferior à do TBHQ, que apresentou o maior período de indução (7,6 h. Após aquecimento, os tratamentos TBHQ e Extrato apresentaram maior capacidade de retenção de tocoferóis e fitosteróis, atingindo valores acima de 88 e 87%, respectivamente. Percentagens similares de ácidos graxos poli-insaturados foram encontradas nos tratamentos OS e Extrato. O extrato de beldroega na concentração 100 mg/kg foi capaz de reduzir as alterações sofridas pelo óleo de soja após aquecimento e pode ser utilizado como substituto natural de antioxidantes sintéticos.

Electron molecular beam epitaxy: Layer-by-layer growth of complex oxides via pulsed electron-beam deposition

International Nuclear Information System (INIS)

Comes, Ryan; Liu Hongxue; Lu Jiwei; Gu, Man; Khokhlov, Mikhail; Wolf, Stuart A.

2013-01-01

Complex oxide epitaxial film growth is a rich and exciting field, owing to the wide variety of physical properties present in oxides. These properties include ferroelectricity, ferromagnetism, spin-polarization, and a variety of other correlated phenomena. Traditionally, high quality epitaxial oxide films have been grown via oxide molecular beam epitaxy or pulsed laser deposition. Here, we present the growth of high quality epitaxial films using an alternative approach, the pulsed electron-beam deposition technique. We demonstrate all three epitaxial growth modes in different oxide systems: Frank-van der Merwe (layer-by-layer); Stranski-Krastanov (layer-then-island); and Volmer-Weber (island). Analysis of film quality and morphology is presented and techniques to optimize the morphology of films are discussed.

Tempo de destilação e perfil volátil do óleo essencial de aroeira da praia (Schinus terebinthifolius em Sergipe

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L.F.M. Oliveira

2014-06-01

Full Text Available Aos frutos e óleos essenciais da aroeira da praia (Schinus terebinthifolius atribui-se atividade antimicrobiana sobre bactérias gram positivas além de ação anti-inflamatória. O óleo essencial da aroeira é utilizado no tratamento de micoses, sendo a sua atividade antifúngica atribuída à alta concentração de monoterpenos. Este estudo teve como objetivo determinar o melhor rendimento de destilação de óleo essencial de sementes e folhas da aroeira e os componentes químicos do óleo essencial nos diversos períodos de destilação. Cem gramas de cada material foram destilados em aparato de Clevenger durante 2,5h, 4,0h, 5,5h e 7,0h. O material destilado foi analisado por cromatografia a gás acoplada a espectrofotômetro de massas, onde foi obtido o perfil cromatográfico do material. As sementes de aroeira apresentaram maiores quantidades de óleo essencial, quando comparadas com as folhas em todos os períodos de destilação. O óleo essencial de aroeira mostrou perfil volátil formado principalmente por mono e sesquiterpenos.

Cartilaginous metaplasia and overgrowth of neurocranium skull after X-irradiation in utero.

Science.gov (United States)

Schmahl, W; Meyer, I; Kriegel, H; Tempel, K H

1979-01-01

Prenatal X-irradiation of mice in the late organogenesis stage either with a fractionated or a single exposure dose (3 X 160 R or 200 R) leads to remarkable, previously undescribed malformations of the skull. These malformations range from mild hyperostotic nodule formation in about 90% of the offspring to excessive formation of desmal bony tissues, which extend deep into the forebrain and are thus only detectable in histological sections. Metaplastic and hyperplastic formation of cartilage in all the neurocranial regions is observed in about 10% of the offspring. The pathogenesis of these overgrowth phenomena is presumably related to a growth disturbance of both the mesenchymal skull primordium and the brain. While malformation of the latter leads to a decrease of intracranial pressure and consequently to altered growth activity of the skull sutures, the reparative and proliferative capacities of the mesenchyme are also stimulated, in a hyperplastic direction, by X-irradiation.

Actividad antimicrobiana de extractos etanólicos de propóleos obtenidos de abejas Apis mellifera.

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Boris Daniel Velasquez

2017-06-01

Full Text Available Propóleos es uno de los productos de la colmena que actualmente viene ganando interés por parte de los investigadores, ya que sus propiedades fisicoquímicas y biológicas, han sido ampliamente reconocidas por su capacidad terapéutica contra una variedad de patógenos humanos y animales, al igual que por su uso potencial contra varios Fitopatógenos. Los estudios demuestran que propóleos es una sustancia compleja, constituida, en promedio, por 300 compuestos diferentes, esta riqueza de compuestos está correlacionada con el origen botánico del cual se obtienen las resinas. Colombia es rica en diversidad botánica, perfilando al país con un alto potencial para obtener propóleos de excelente calidad, los cuales con estudios juiciosos, se constituiría estos últimos como alternativas novedosas para el control y el tratamiento de gran variedad de patógenos causantes de enfermedades.

Degradation of Silicon Carbide Reflective Surfaces in the LEO Environment

Science.gov (United States)

Mileti, Sandro; Coluzzi, Plinio; Marchetti, Mario

2009-01-01

Space mirrors in Low Earth Orbit (LEO) encounter a degradation problem caused by the impact of atomic oxygen (ATOX) in the space environment. This paper presents an experiment of the atomic oxygen impact degradation and UV synergic effects on ground simulation. The experiment was carried out in a dedicated ATOX simulation vacuum chamber. As target materials, a polished CVD Beta-silicon carbide (SiC) coating was investigated. The selection of silicon carbide is due to its high potential candidate as a mirror layer substrate material for its good reflectance at UV wavelengths and excellent thermal diffusivity. It has highly desirable mechanical and thermal properties and can achieve an excellent surface finish. The deposition of the coatings were on carbon-based material substrate; i.e., silicon impregnated carbon fiber composite (C/SiC). Mechanical and thermal properties of the coatings such as hardness and Coefficient of Thermal Expansion (CTE) were achieved. Several atomic oxygen impact angles were studied tilting the target samples respect to the flux direction. The various impact angles permitted to analyze the different erosion rates and typologies which the mirrors would encounter in LEO environment. The degradation was analyzed in various aspects. Macroscopic mass loss per unit area, surface roughness and morphology change were basically analyzed. The exposed surfaces of the materials were observed through a Scanning Electron Microscope (SEM). Secondly, optical diagnostic of the surfaces were performed in order to investigate their variation in optical properties as the evaluation of reflectance degradation. The presence of micro-cracks caused by shrinkage, grinding, polishing or thermal cycling and the porosity in the coatings, could have led to the undercutting phenomenon. Observation of uprising of undercutting was also conducted. Remarks are given regarding capabilities in short-term mission exposures to the LEO environment of this coating.

Leo Burnett wins agency of the year title in Estonia and Lithuania

Index Scriptorium Estoniae

2004-01-01

Eesti Kuldmuna reklaamikonkursil, Leedu reklaamifestivalil Adrenalinas aasta reklaamiagentuuri tiitli pälvinud ettevõttest Kontuur Leo Burnett. Madis Laas, Tomas Ramanauskas ja Marius Petrukaitis vastavad küsimustele firma edu võimalike põhjuste ja tulevikuplaanide kohta

Electronic properties of epitaxial 6H silicon carbide

International Nuclear Information System (INIS)

Wessels, B.W.; Gatos, H.C.

1977-01-01

The electrical conductivity and Hall coefficient were measured in the temperature range from 78 to 900 K for n-type epitaxially grown 6H silicon carbide. A many-valley model of the conduction band was used in the analysis of electron concentration as a function of temperature. From this analysis, the density of states mass to the free electron mass ratio per ellipsoid was calculated to be 0.45. It was estimated that the constant energy surface of the conduction band consists of three ellipsoids. The ionization energy of the shallowest nitrogen donor was found to be 105 meV, when the valley-orbit interaction was taken into account. The electron scattering mechanisms in the epitaxial layers were analyzed and it was shown that the dominant mechanism limiting electron mobility at high temperatures is inter-valley scattering and at low temperatures (200K), impurity and space charge scattering. A value of 360 cm 2 /V sec was calculated for the maximum room temperature Hall mobility expected for electrons in pure 6H SiC. The effect of epitaxial growth temperature on room temperature Hall mobility was also investigated. (author)

Fontes de óleo na dieta e sua influência no desempenho e na imunidade de frangos de corte

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Marcos F. Pinto

2014-05-01

Full Text Available A composição de ácidos graxos da dieta pode influenciar o desempenho produtivo e o sistema imune de frangos de corte. O objetivo deste estudo foi avaliar o efeito do consumo de óleos ricos em ácidos graxos poli-insaturados ômega-6 (PUFAs n-6 e ômega-3 (PUFAs n-3 sobre o desempenho e a resposta imunológica de frangos de corte frente a um desafio antigênico. Foram comparadas dietas formuladas com 7% de óleo de soja (OS, linhaça (OL ou sardinha (OP, fornecidas a 240 frangos da linhagem Cobb, divididos em 24 grupos de 10 aves cada, num arranjo experimental 3x2 (3 tipos de óleo e aves vacinadas ou não vacinadas e 4 repetições. O óleo de soja é rico em ácido linoleico, um PUFA n-6, o óleo de linhaça é fonte de ácido alfa-linolênico, um PUFA n-3, e o óleo de sardinha, de outros PUFAs n-3, como os ácidos eicosapentaenoico e docosahexaenoico. O consumo de ração, o ganho de peso e a conversão alimentar foram avaliados aos 21, 35 e 42 dias. Aos 7 e aos 21 dias de idade, metade das aves recebeu vacina contra doença de Newcastle. Quinze dias após a imunização, avaliou-se a produção de anticorpos pelo método de ELISA, expressa pela densidade óptica a 450 nm (D.O. 450nm. Apenas as aves alimentadas com ração contendo OS apresentaram maior imunidade humoral (P0,05. Entre as aves que receberam dieta com OS, as aves vacinadas apresentaram pior conversão alimentar (P0,05, considerando todo o período experimental. A utilização de óleo rico em PUFA n-6 na dieta de frangos de corte aumentou a resposta humoral, mas não influenciou a resposta celular frente a um desafio antigênico.

Complex Nanostructures by Pulsed Droplet Epitaxy

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Noboyuki Koguchi

2011-06-01

Full Text Available What makes three dimensional semiconductor quantum nanostructures so attractive is the possibility to tune their electronic properties by careful design of their size and composition. These parameters set the confinement potential of electrons and holes, thus determining the electronic and optical properties of the nanostructure. An often overlooked parameter, which has an even more relevant effect on the electronic properties of the nanostructure, is shape. Gaining a strong control over the electronic properties via shape tuning is the key to access subtle electronic design possibilities. The Pulsed Dropled Epitaxy is an innovative growth method for the fabrication of quantum nanostructures with highly designable shapes and complex morphologies. With Pulsed Dropled Epitaxy it is possible to combine different nanostructures, namely quantum dots, quantum rings and quantum disks, with tunable sizes and densities, into a single multi-function nanostructure, thus allowing an unprecedented control over electronic properties.

Estudo comparativo dos óleos voláteis de algumas espécies de Piperaceae

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J.M.O. Mesquita

Full Text Available O presente trabalho teve por objetivo a análise comparativa dos óleos voláteis de espécies da família Piperaceae. As espécies estudadas foram as seguintes: Piper aduncum, P. amalago, P. arboreum, P. cernuum, P. hispidum, P. regnelii, P. submarginalum, P. vicosanum e Pothomorphe umbellata. A análise dos óleos voláteis foi efetuada pela combinação de técnicas de Cromatografia de Fase Gasosa (CG e de Cromatografia de Fase Gasosa acoplada a Espectrometria de Massa (CG/EM. A porcentagem de identificação dos constituintes nas análises dos óleos voláteis de Piper aduncum, P. amalago, P. vicosanum, P. submarginalum e Pothomorphe umbellata, atingiu valores superiores a 80%. Houve predominância de compostos de natureza sesquiterpênica nas composições químicas das espécies analisadas, com exceção de P. hispidum, P. submarginalum e P. vicosanum onde a predominância na composição foi de monoterpenos. Pelos dados apresentados observou-se que, dentre os compostos majoritários, os mais freqüentes, nas 9 espécies estudadas, foram beta-pineno (9/9 e espatulenol (9/9, seguidos por E-cariofileno (8/9, óxido de cariofileno (8/9, germacreno D (7/9, alfa-pineno (7/9 e limoneno (6/9. Pela primeira vez se relata a composição dos óleos voláteis de P. submarginalum e P vicosanum.

Potential advantages and limitations of the Leo stent in endovascular treatment of complex cerebral aneurysms

Energy Technology Data Exchange (ETDEWEB)

Lv Xianli; Li Youxiang; Jiang Chuhan; Yang Xinjian [Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, 6, Tiantan Xili, 100050 Hebei, Beijing (China); Wu Zhongxue, E-mail: ttyyzjb@sina.com [Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, 6, Tiantan Xili, 100050 Hebei, Beijing (China)

2011-08-15

Objective: The Leo self-expandable stent is a new retractable stent that is delivered via a conventional catheter. The aim of this study was to evaluate the use of this stent for endovascular treatment of complex aneurysms. Methods: Twenty-eight complex cerebral aneurysms (27 saccular and 1 fusiform) in 28 patients were treated electively. They were located at the internal carotid artery (17), basilar trunk (3), anterior cerebral artery (1), anterior communicating artery (3), vertebral artery (2) and middle cerebral artery (2). One aneurysm exhibited recanalization after primary endovascular treatment without stent. Clinical outcome was assessed with the modified Glasgow Outcome Scale. Results: Deployment of Leo stent was successful in 26 lesions, and difficulties in stent positioning due to tortuous cerebral circulation in 2 cases, which were treated with Neuroform stent. Additional coil embolization was performed in 26 lesions. No permanent neurological deficits were encountered consequent to endovascular procedure. Complete or partial occlusion immediately after stent deployment was achieved in all aneurysms. There was no immediate coil embolization was chosen in 3 cases because of subsequent reduced filling of the aneurysms with contrast agent on angiograms. There were 3 asymptomatic parent artery occlusion related to the deployment of the Leo stent, one stent migration. Follow-up revealed patent stents in the remaining cases. No angiographic recurrences arose. Conclusion: The Leo stent is very useful for endovascular treatment of complex cerebral aneurysms because it is easy to navigate and place precisely. A drawback is that in-stent thrombosis caused by stent placement and stiffer delivery catheters to place larger stents.

Estimating Solar Proton Flux at LEO From a Geomagnetic Cutoff Model

Science.gov (United States)

2015-07-14

simple shadow cones (using nomenclature from Stormer theory of particle motion in a dipole magnetic field [6]), that result from particles trajectories...basic Stormer theory [7]. However, in LEO the changes would be small relative to uncertainties in the model and therefore unnecessary. If the model were

Controlling the Growth of Future LEO Debris Populations with Active Debris Removal

Science.gov (United States)

Liou, J.-C.; Johnson, N. L.; Hill, N. M.

2008-01-01

Active debris removal (ADR) was suggested as a potential means to remediate the low Earth orbit (LEO) debris environment as early as the 1980s. The reasons ADR has not become practical are due to its technical difficulties and the high cost associated with the approach. However, as the LEO debris populations continue to increase, ADR may be the only option to preserve the near-Earth environment for future generations. An initial study was completed in 2007 to demonstrate that a simple ADR target selection criterion could be developed to reduce the future debris population growth. The present paper summarizes a comprehensive study based on more realistic simulation scenarios, including fragments generated from the 2007 Fengyun-1C event, mitigation measures, and other target selection options. The simulations were based on the NASA long-term orbital debris projection model, LEGEND. A scenario, where at the end of mission lifetimes, spacecraft and upper stages were moved to 25-year decay orbits, was adopted as the baseline environment for comparison. Different annual removal rates and different ADR target selection criteria were tested, and the resulting 200-year future environment projections were compared with the baseline scenario. Results of this parametric study indicate that (1) an effective removal strategy can be developed based on the mass and collision probability of each object as the selection criterion, and (2) the LEO environment can be stabilized in the next 200 years with an ADR removal rate of five objects per year.

Multiple delta doping of single crystal cubic boron nitride films heteroepitaxially grown on (001)diamonds

Science.gov (United States)

Yin, H.; Ziemann, P.

2014-06-01

Phase pure cubic boron nitride (c-BN) films have been epitaxially grown on (001) diamond substrates at 900 °C. The n-type doping of c-BN epitaxial films relies on the sequential growth of nominally undoped (p-) and Si doped (n-) layers with well-controlled thickness (down to several nanometer range) in the concept of multiple delta doping. The existence of nominally undoped c-BN overgrowth separates the Si doped layers, preventing Si dopant segregation that was observed for continuously doped epitaxial c-BN films. This strategy allows doping of c-BN films can be scaled up to multiple numbers of doped layers through atomic level control of the interface in the future electronic devices. Enhanced electronic transport properties with higher hall mobility (102 cm2/V s) have been demonstrated at room temperature as compared to the normally continuously Si doped c-BN films.

Tagakiusamine ja kirjutamiskunst / Leo Strauss ; järelsõna Jüri Lipping

Index Scriptorium Estoniae

Strauss, Leo, 1899-1973

2000-01-01

Ajalooliste tekstide ridade vahele peidetud sõnumi lugemisest. Tsensuuri mõjust filosoofilistele tekstidele. Peidetud sõnumi lugemisest lähtuvast erinevusest eelmoodsate ja uusaegsete filosoofide teostes. Jüri Lipping'u järelsõna Leo Straussi filosoofilistest vaadetest.

Molecular beam epitaxy of Cd3As2 on a III-V substrate

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Timo Schumann

2016-12-01

Full Text Available Epitaxial, strain-engineered Dirac semimetal heterostructures promise tuning of the unique properties of these materials. In this study, we investigate the growth of thin films of the recently discovered Dirac semimetal Cd3As2 by molecular beam epitaxy. We show that epitaxial Cd3As2 layers can be grown at low temperatures (110 °C–220 °C, in situ, on (111 GaSb buffer layers deposited on (111 GaAs substrates. The orientation relationship is described by ( 112 Cd 3 As 2 || (111 GaSb and [ 1 1 ¯ 0 ] Cd 3 As 2 || [ 1 ¯ 01 ] GaSb . The films are shown to grow in the low-temperature, vacancy ordered, tetragonal Dirac semimetal phase. They exhibit high room temperature mobilities of up to 19300 cm2/Vs, despite a three-dimensional surface morphology indicative of island growth and the presence of twin variants. The results indicate that epitaxial growth on more closely lattice matched buffer layers, such as InGaSb or InAlSb, which allow for imposing different degrees of epitaxial coherency strains, should be possible.

Caracterização físico-química de misturas de óleos vegetais para fins alimentares

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Katcilanya Menezes Almeida

2013-05-01

Full Text Available Objetivou-se, com este trabalho, a elaboração e caracterização de misturas especiais de óleos vegetais para fins alimentícios, com base nos óleos de amendoim, gergelim, maracujá e soja. Os óleos de amendoim e gergelim foram extraídos de sementes das cultivares BRS-Havana e BRS-Seda, respectivamente, cedidas pela Embrapa Algodão enquanto o óleo de maracujá foi adquirido no comércio de São Paulo e o de soja no de Campina Grande. As misturas foram elaboradas com base em uma matriz de planejamento experimental e, em seguida, submetidas aos ensaios físico-químicas (umidade, índice de acidez, índice de iodo, índice de refração, densidade e viscosidade segundo a metodologia do IAL (2008. Os resultados foram submetidos à análise de variância (ANOVA por delineamento inteiramente casualizado com 17 tratamentos e 6 variáveis pelo software ASSISTAT versão 7.6 beta. Todas as misturas diferiram estatisticamente entre si a nível de 1% pelo teste de Tukey e apresentaram-se aptas para fins alimentares, com influência da significante quantidade de ácidos graxos insaturados em todas as medidas físico-quimicas. Os óleos de maracujá e soja são quimicamente semelhantes.

Complete mitochondrial genome of a Asian lion (Panthera leo goojratensis).

Science.gov (United States)

Li, Yu-Fei; Wang, Qiang; Zhao, Jian-ning

2016-01-01

The entire mitochondrial genome of this Asian lion (Panthera leo goojratensis) was 17,183 bp in length, gene composition and arrangement conformed to other lions, which contained the typical structure of 22 tRNAs, 2 rRNAs, 13 protein-coding genes and a non-coding region. The characteristic of the mitochondrial genome was analyzed in detail.

Top-gate dielectric induced doping and scattering of charge carriers in epitaxial graphene

Science.gov (United States)

Puls, Conor P.; Staley, Neal E.; Moon, Jeong-Sun; Robinson, Joshua A.; Campbell, Paul M.; Tedesco, Joseph L.; Myers-Ward, Rachael L.; Eddy, Charles R.; Gaskill, D. Kurt; Liu, Ying

2011-07-01

We show that an e-gun deposited dielectric impose severe limits on epitaxial graphene-based device performance based on Raman spectroscopy and low-temperature transport measurements. Specifically, we show from studies of epitaxial graphene Hall bars covered by SiO2 that the measured carrier density is strongly inhomogenous and predominantly induced by charged impurities at the grapheme/dielectric interface that limit mobility via Coulomb interactions. Our work emphasizes that material integration of epitaxial graphene and a gate dielectric is the next major road block towards the realization of graphene-based electronics.

Anatase thin film with diverse epitaxial relationship grown on yttrium stabilized zirconia substrate by chemical vapor deposition

International Nuclear Information System (INIS)

Miyagi, Takahira; Ogawa, Tomoyuki; Kamei, Masayuki; Wada, Yoshiki; Mitsuhashi, Takefumi; Yamazaki, Atsushi

2003-01-01

An anatase epitaxial thin film with diverse epitaxial relationship, YSZ (001) // anatase (001), YSZ (010) // anatase (110), was grown on a single crystalline yttrium stabilized zirconia (YSZ) (001) substrate by metal organic chemical vapor deposition (MOCVD). The full width at half maximum (FWHM) of the (004) reflection of this anatase epitaxial film was 0.4deg, and the photoluminescence of this anatase epitaxial film showed visible emission with broad spectral width and large Stokes shift at room temperature. These results indicate that this anatase epitaxial film possessed almost equal crystalline quality compared with that grown under identical growth conditions on single crystalline SrTiO 3 substrate. (author)

Determinação dos valores energéticos de alguns óleos e gorduras para pintos de corte machos e fêmeas aos 21 dias de idade

OpenAIRE

Nascif,Carla Cristina Cardoso; Gomes,Paulo Cezar; Albino,Luiz Fernando Teixeira; Rostagno,Horacio Santiago

2004-01-01

Foi realizado um ensaio biológico com pintos de corte no período de 21 a 32 dias de idade, com o objetivo de determinar os valores de energia metabolizável aparente (EMA) e energia metabolizável aparente corrigida pela retenção de nitrogênio (EMAn) do óleo de soja degomado, óleo de milho, óleo de canola, gordura de aves, gordura de coco, gordura suína, sebo bovino e de duas misturas, sendo a primeira composta de óleo de soja degomado + gordura de coco e a segunda de óleo de soja degomado + se...

STM investigation of epitaxial Si growth for the fabrication of a Si-based quantum computer

Energy Technology Data Exchange (ETDEWEB)

Oberbeck, Lars; Hallam, Toby; Curson, Neil J.; Simmons, Michelle Y.; Clark, Robert G

2003-05-15

We investigate the morphology of epitaxial Si layers grown on clean and on hydrogen terminated Si(0 0 1) to explore the growth strategy for the fabrication of a Si-based quantum computer. We use molecular beam epitaxy to deposit 5 monolayers of silicon at a temperature of 250 deg. C and scanning tunnelling microscopy to image the surface at room temperature after growth and after various rapid annealing steps in the temperature range of 350-600 deg. C. The epitaxial layer grown on the hydrogenated surface shows a significantly higher surface roughness due to a lower mobility of silicon surface atoms in the presence of hydrogen. Annealing at temperatures {>=}550 deg. C reduces the roughness of both epitaxial layers to the value of a clean silicon surface. However, the missing dimer defect density of the epitaxial layer grown on the hydrogenated surface remains higher by a factor of two compared to the layer grown on clean Si(0 0 1). Our results suggest a quantum computer growth strategy in which the hydrogen resist layer is desorbed before the epitaxial silicon layer is grown at low temperature to encapsulate phosphorus quantum bits.

Caracterización de propóleos provenientes del municipio de Caldas obtenido por dos métodos de recolección

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Julián Martínez G.

2012-04-01

Full Text Available Objetivo. Determinar las características fisicoquímicas y la actividad antimicrobiana de propóleos de Apis mellifera, provenientes del municipio de Caldas, obtenidos por dos métodos de recolección. Materiales y métodos. Se utilizaron dos métodos de recolección: de raspado y trampa plastica. Se estableció el contenido de cera, ceniza, material insoluble y resina de los propóleos crudos. Al extracto etanólico de los propóleos se les determinó el perfil cromatográfico (GC-MS y el espectro UV; además, se evaluó la actividad antimicrobiana in vitro frente a hongos (Aspergillus sp., Penicillium sp., Colletotrichum acutatum y C. gloesporioides, y bacterias (Salmonella tiphy, Bacillus subtilis, Staphylococcus aureus y Escherichia coli. Resultados. El material obtenido mediante malla matrizada presentó un perfil químico amplio, buena actividad antimicrobiana y mejores parámetros de calidad, de acuerdo con estándares establecidos por normas internacionales que los propóleos obtenidos por el método de raspado. Además, pudo observarse que la acción antimicrobiana de los propóleos fue dependiente de la concentración del extracto y del hongo o bacteria evaluada. Conclusiones. La composición química y la actividad antibacteriana y antifúngica de los propóleos están relacionadas con el método de recolección. El presente estudio aporta información para la selección de la técnica de cosecha del propóleo de acuerdo con la aplicación que se desee dar.

A Young Star Cluster in the Leo a Galaxy

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Stonkutė R.

2015-09-01

Full Text Available We report a serendipitous discovery of a star cluster in the dwarf irregular galaxy Leo A. Young age (~28 Myr and low mass (~510 M⊙ estimates are based on the isochrone fit assuming a metallicity derived for HII regions (Z = 0.0007. The color-magnitude diagrams of the stars, located in and around the cluster area, and the results of aperture photometry of the cluster itself are presented.

Defect mediated van der Waals epitaxy of hexagonal boron nitride on graphene

Science.gov (United States)

Heilmann, M.; Bashouti, M.; Riechert, H.; Lopes, J. M. J.

2018-04-01

Van der Waals heterostructures comprising of hexagonal boron nitride and graphene are promising building blocks for novel two-dimensional devices such as atomically thin transistors or capacitors. However, demonstrators of those devices have been so far mostly fabricated by mechanical assembly, a non-scalable and time-consuming method, where transfer processes can contaminate the surfaces. Here, we investigate a direct growth process for the fabrication of insulating hexagonal boron nitride on high quality epitaxial graphene using plasma assisted molecular beam epitaxy. Samples were grown at varying temperatures and times and studied using atomic force microscopy, revealing a growth process limited by desorption at high temperatures. Nucleation was mostly commencing from morphological defects in epitaxial graphene, such as step edges or wrinkles. Raman spectroscopy combined with x-ray photoelectron measurements confirm the formation of hexagonal boron nitride and prove the resilience of graphene against the nitrogen plasma used during the growth process. The electrical properties and defects in the heterostructures were studied with high lateral resolution by tunneling current and Kelvin probe force measurements. This correlated approach revealed a nucleation apart from morphological defects in epitaxial graphene, which is mediated by point defects. The presented results help understanding the nucleation and growth behavior during van der Waals epitaxy of 2D materials, and point out a route for a scalable production of van der Waals heterostructures.

GaN epitaxial layers grown on multilayer graphene by MOCVD

Science.gov (United States)

Li, Tianbao; Liu, Chenyang; Zhang, Zhe; Yu, Bin; Dong, Hailiang; Jia, Wei; Jia, Zhigang; Yu, Chunyan; Gan, Lin; Xu, Bingshe

2018-04-01

In this study, GaN epitaxial layers were successfully deposited on a multilayer graphene (MLG) by using metal-organic chemical vapor deposition (MOCVD). Highly crystalline orientations of the GaN films were confirmed through electron backscatter diffraction (EBSD). An epitaxial relationship between GaN films and MLG is unambiguously established by transmission electron microscope (TEM) analysis. The Raman spectra was used to analyze the internal stress of GaN films, and the spectrum shows residual tensile stress in the GaN films. Moreover, the results of the TEM analysis and Raman spectra indicate that the high quality of the MLG substrate is maintained even after the growth of the GaN film. This high-quality MLG makes it possible to easily remove epitaxial layers from the supporting substrate by micro-mechanical exfoliation technology. This work can aid in the development of transferable devices using GaN films.

PURIFICAÇÃO DE ÓLEOS VEGETAIS POR EXTRAÇÃO COM CO2 SUPERCRÍTICO

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Pedro L. M. PENEDO

1997-12-01

Full Text Available Este estudo constatou a possibilidade de extrairem-se ácidos graxos livres de óleos vegetais com CO2 supercrítico. Utilizou-se neste trabalho óleos de soja e de castanha do Pará. A pesquisa desenvolveu-se em duas etapas, inicialmente investigou-se a possibilidade de se extrairem os ácidos graxos destes óleos em condições de extração que variaram de 50-140 bar e de 40-80oC durante 40-160 minutos. Concluiu-se que é possível realizar a desacidificação de óleos vegetais. A eficiência da extração foi de aproximadamente 30% a 140 bar e 80oC para ambos os óleos. Após esta primeira etapa, o próximo passo foi a tentativa de obter-se um aumento na eficiência do processo promovendo a pré-degomagem nos óleos brutos como uma etapa anterior ao processo de desacidificação com CO2 supercrítico. A degomagem foi realizada através de dois métodos diferentes, um para extrair as gomas hidratáveis e outro para extrair tanto as hidratáveis como as não-hidratáveis. Os resultados experimentais foram obtidos a 140 bar e 80oC durante 40-160 minutos, mostrando que a pré-degomagem é realmente necessária, pois a eficiência da extração aumentou para 57% para o óleo de soja e 42% para o de castanha do Pará totalmente degomados, sendo que o método escolhido deve extrair tanto as gomas hidratáveis como as não-hidratáveis. Finalmente, utilizou-se cossolvente (etanol a 1-5% do peso do óleo para auxiliar a extração, observando-se um aumento na eficiência para aproximadamente 65% para o óleo de soja e 56% para o de castanha do Pará totalmente degomados a 140 bar e 80oC por 40-160 minutos.Purification of Vegetable Oils using Supercritical CO2. This work presents a study on the extraction of free fatty acids from crude soy and Brazil nut oils, using supercritical carbon dioxide. It was developed in two stages, at first moment we verified the possibility to extract free fatty acids from these oils and then the extraction conditions

Interaction of GaN epitaxial layers with atomic hydrogen

Energy Technology Data Exchange (ETDEWEB)

Losurdo, M.; Giangregorio, M.M.; Capezzuto, P.; Bruno, G.; Namkoong, G.; Doolittle, W.A.; Brown, A.S

2004-08-15

GaN surface passivation processes are still under development and among others hydrogen treatments are investigated. In this study, we use non-destructive optical and electrical probes such as spectroscopic ellipsometry (SE) and surface potential Kelvin probe microscopy (SP-KPM) in conjunction with non-contact atomic force microscopy (AFM) for the study of the different reactivity of Ga-polar and N-polar GaN epitaxial layers with atomic hydrogen. The GaN epitaxial layers are grown by molecular beam epitaxy on sapphire (0 0 0 1) substrates, and GaN and AlN buffer layers are used to grow N-polar and Ga-polar films, respectively. The atomic hydrogen is produced by a remote rf (13.56 MHz) H{sub 2} plasma in order to rule out any ion bombardment of the GaN surface and make the interaction chemical. It is found that the interaction of GaN surfaces with atomic hydrogen depends on polarity, with N-polar GaN exhibiting greater reactivity. Furthermore, it is found that atomic hydrogen is effective in the passivation of grain boundaries and surface defects states.

Interaction of GaN epitaxial layers with atomic hydrogen

International Nuclear Information System (INIS)

Losurdo, M.; Giangregorio, M.M.; Capezzuto, P.; Bruno, G.; Namkoong, G.; Doolittle, W.A.; Brown, A.S.

2004-01-01

GaN surface passivation processes are still under development and among others hydrogen treatments are investigated. In this study, we use non-destructive optical and electrical probes such as spectroscopic ellipsometry (SE) and surface potential Kelvin probe microscopy (SP-KPM) in conjunction with non-contact atomic force microscopy (AFM) for the study of the different reactivity of Ga-polar and N-polar GaN epitaxial layers with atomic hydrogen. The GaN epitaxial layers are grown by molecular beam epitaxy on sapphire (0 0 0 1) substrates, and GaN and AlN buffer layers are used to grow N-polar and Ga-polar films, respectively. The atomic hydrogen is produced by a remote rf (13.56 MHz) H 2 plasma in order to rule out any ion bombardment of the GaN surface and make the interaction chemical. It is found that the interaction of GaN surfaces with atomic hydrogen depends on polarity, with N-polar GaN exhibiting greater reactivity. Furthermore, it is found that atomic hydrogen is effective in the passivation of grain boundaries and surface defects states

ATIVIDADE DE DETERRÊNCIA ALIMENTAR DO ÓLEO ESSENCIAL DE LARANJA AMARGA SOBRE Helicoverpa armigera HÜBNER

Directory of Open Access Journals (Sweden)

Victor Luiz de Souza Lima

2017-01-01

Full Text Available Diversas plantas possuem compostos secundários com propriedades inseticidas e o óleo essencial de laranja amarga mostra-se com grande potencial para o controle de pragas. Recentemente, foi registrada no Brasil a espécie Helicoverpa armigera, uma das maiores pragas da agricultura mundial. Tendo em vista a falta de métodos alternativos aos inseticidas para o controle dessa praga, o objetivo desse trabalho foi avaliar os efeitos do óleo essencial de laranja amarga sobre H. armigera. Foi realizado um teste de escolha para avaliar a atividade deterrente. Folhas de tomate foram imersas em soluções contendo óleo de laranja amarga em três concentrações (1, 10 e 100 mg L-1. As folhas tratadas com óleo e folhas não tratadas foram oferecidas à lagartas de segunda instar e após 24h foi calculado o índice de deterrência alimentar (IDA. A concentração de 1 mg L-1 apresentou 71% de deterrência alimentar. Porém as concentrações de 10 e 100 mg L-1 causaram fitotoxidez às folhas de tomate, inviabilizando o consumo pelas lagartas e a estimativa do IDA. Novos testes devem ser realizados com concentrações menores para evitar a fitotoxidez.

Clinical value of radionuclide small intestine transit time measurement combined with lactulose hydrogen breath test for the diagnosis of bacterial overgrowth in irritable bowel syndrome.

Science.gov (United States)

Ning, Yanli; Lou, Cen; Huang, Zhongke; Chen, Dongfang; Huang, Huacheng; Chen, Liang; Zhang, Bucheng; Dai, Ning; Zhao, Jianmin; Zhen, Xia

2016-01-01

Small intestine bacterial overgrowth (SIBO) may be a pathogenetic factor for irritable bowel syndrome (IBS). This syndrome cannot be explained by structural abnormalities and has no specific diagnostic laboratory tests or biomarkers. We studied quantitatively and semi-quantitatively, using lactulose hydrogen breath test (LHBT), small intestinal transit time (SITT) (99m)technetium-diethylene triamine pentaacetic acid ((99m)Tc-DTPA) in order to examine the mobility of small intestine as an indication of bacterial overgrowth in patients. Eighty nine consecutive patients who met Rome criteria for IBS were retrospectively studied. According to the diagnostic criteria, all patients were divided into two groups: the SIBO group and the non-SIBO group. The tracer was a mixture of 10g lactulose, 37MBq (99m)Tc-DTPA and 100mL water. The patient drank the whole mixture during 1min and the SITT study started immediately. The SITT and the LHBT followed every 15min for up to 3h after emptying the urine bladder. Spearman's rank correlation was applied to assess the correlation of oro-cecum transit time (OCTT) between imaging and LHBT. The semi-quantitative index between the SIBO group and the non-SIBO group was analyzed with Wilcoxon's rank sum test. If there was significant group difference, the receiver operating characteristic (ROC) curve was used. Pintestinal transit time study using a lactose hydrogen breath test and (99m)Tc-DTPA is a real-time test for small intestine bacteria overgrowth in IBS patients and can be used as an indicator of the disease.

Toxicidade de óleos essenciais de Piper aduncum e Piper hispidinervum em Sitophilus zeamais

OpenAIRE

Estrela,Joelma Lima Vidal; Fazolin,Murilo; Catani,Valdomiro; Alécio,Marcio Rodrigues; Lima,Marilene Santos de

2006-01-01

Óleos essenciais de Piper aduncum L. e Piper hispidinervum C.DC. (Piperaceae) foram avaliados quanto ao efeito inseticida em Sitophilus zeamais Motsch. por ação de contato, fumigação e tópica. Na determinação da DL50 e CL50, foi utilizada a análise de Probit. Médias porcentuais de mortalidade dos insetos foram comparadas por meio da análise de regressão linear e superposição das barras do erro padrão. S. zeamais foi mais suscetível ao efeito de contato do óleo de P. hispidinervum em relação a...

Increased placental nutrient transport in a novel mouse model of maternal obesity with fetal overgrowth.

Science.gov (United States)

Rosario, Fredrick J; Kanai, Yoshikatsu; Powell, Theresa L; Jansson, Thomas

2015-08-01

To identify possible mechanisms linking obesity in pregnancy to increased fetal adiposity and growth, a unique mouse model of maternal obesity associated with fetal overgrowth was developed, and the hypothesis that maternal obesity causes up-regulation of placental nutrient transporter expression and activity was tested. C57BL/6J female mice were fed a control (C) or a high-fat/high-sugar (HF/HS) pelleted diet supplemented by ad libitum access to sucrose (20%) solution, mated, and studied at embryonic day 18.5. HF/HS diet increased maternal fat mass by 2.2-fold (P Maternal circulating insulin, leptin, and cholesterol were increased (P maternal obesity. © 2015 The Obesity Society.

A comparative study of transport properties in polycrystalline and epitaxial chromium nitride films

KAUST Repository

Duan, X. F.

2013-01-08

Polycrystalline CrNx films on Si(100) and glass substrates and epitaxial CrNx films on MgO(100) substrates were fabricated by reactive sputtering with different nitrogen gas flow rates (fN2). With the increase of fN2, a lattice phase transformation from metallic Cr2N to semiconducting CrN appears in both polycrystalline and epitaxial CrNx films. At fN2= 100 sccm, the low-temperature conductance mechanism is dominated by both Mott and Efros-Shklovskii variable-range hopping in either polycrystalline or epitaxial CrN films. In all of the polycrystalline and epitaxial films, only the polycrystalline CrNx films fabricated at fN2 = 30 and 50 sccm exhibit a discontinuity in ρ(T) curves at 260-280 K, indicating that both the N-vacancy concentration and grain boundaries play important roles in the metal-insulator transition. © 2013 American Institute of Physics.

Actividad antiurolítica del extracto etanólico de propóleo ayacuchano en ratas

Directory of Open Access Journals (Sweden)

Rita López-Cabanillas

Full Text Available RESUMEN Objetivos Determinar la actividad antiurolítica del extracto etanólico de propóleo ayacuchano en un modelo preventivo de urolitiasis inducido en ratas. Materiales y métodos Se estudiaron 45 ratas albinas macho Sprague-Dawley. El efecto antiurolítico se analizó en cinco grupos de seis animales: blanco, control (1 mL de etilenglicol al 5% y 1 mL cloruro de amonio al 5% y tres grupos tratados con el extracto etanólico de propóleo a dosis diaria de 250, 350 y 500 mg/Kg. Las sustancias fueron administradas mediante canulación orogástrica durante 16 días. El efecto diurético se evaluó en 15 ratas distribuidas en cinco grupos: blanco, control (furosemida 20 mg/Kg y tres grupos tratados con extracto etanólico de propóleo a dosis de 250, 350 y 500 mg/Kg. Se midió el pH urinario, densidad urinaria y sedimentación del oxalato de calcio; la presencia de cálculos renales se evaluó mediante cortes histopatológicos por tinción con hematoxilina-eosina bajo luz polarizada. Resultados El extracto etanólico de propóleo ayacuchano produjo cambios significativos en los valores de ácido úrico, lactato deshidrogenasa sérico, pH, densidad urinaria al comparar los tres grupos dosis; en el análisis histológico observado a luz polarizada se observó menor presencia de cristales de oxalato de calcio en células tubulares del riñón en el grupo tratado a dosis de 250 mg/Kg; el efecto diurético en el grupo tratado con dosis de 250 mg/kg fue mayor en comparación con la furosemida. Conclusiones El extracto etanólico de propóleo ayacuchano presenta actividad antiurolítica en el modelo preventivo de urolitiasis en ratas albinas.

Effect of LEO cycling on 125 Ah advanced design IPV nickel-hydrogen battery cells

Science.gov (United States)

Smithrick, John J.; Hall, Stephen W.

1990-01-01

An advanced 125 Ah individual pressure vessel (IPV) nickel-hydrogen cell was designed. The primary function of the advanced cell is to store and deliver energy for long-term, low earth-orbit (LEO) spacecraft missions. The new features of this design are: (1) use of 26 percent rather than 31 percent potassium hydroxide (KOH) electrolyte, (2) use of a patented catalyzed wall wick, (3) use of serrated-edge separators to facilitate gaseous oxygen and hydrogen flow within the cell, while still maintaining physical contact with the wall wick for electrolyte management, and (4) use of a floating rather than a fixed stack (state-of-the-art) to accommodate nickel electrode expansion. Six 125-Ah flight cells based on this design were fabricated by Eagle-Picher. Three of the cells contain all of the advanced features (test cells) and three are the same as the test cells except they don't have catalyst on the wall wick (control cells). All six cells are in the process of being evaluated in a LEO cycle life test. The cells have accumulated about 4700 LEO cycles (60 percent DOD 10 C). There have been no cell failures; the catalyzed wall wick cells, however, are performing better.

New insights into microstructural evolution of epitaxial Ni-Mn-Ga films on MgO (1 0 0) substrate by high-resolution X-ray diffraction and orientation imaging investigations

Science.gov (United States)

Sharma, Amit; Mohan, Sangeneni; Suwas, Satyam

2018-04-01

In this work, a detailed investigation has been performed on hetero-epitaxial growth and microstructural evolution in highly oriented Ni-Mn-Ga (1 0 0) films grown on MgO (1 0 0) substrate using high-resolution X-ray diffraction and orientation imaging microscopy. Mosaicity of the films has been analysed in terms of tilt angle, twist angle, lateral and vertical coherence length and threading dislocation densities by performing rocking curve measurements and reciprocal space mapping. Density of edge dislocations is found to be an order of magnitude higher than the density of screw dislocations, irrespective of film thickness. X-ray pole figure measurements have revealed an orientation relationship of ? || (1 0 0)MgO; ? || [0 0 1]MgO between the film and substrate. Microstructure predicted by X-ray diffraction is in agreement with that obtained from electron microscopy and atomic force microscopy. The evolution of microstructure in the film with increasing thickness has been explained vis-à-vis dislocation generation and growth mechanisms. Orientation imaging microscopy observations indicate evolutionary growth of film by overgrowth mechanism. Decrease in coercivity with film thickness has been explained as an interplay between stress field developed due to crystal defects and magnetic domain pinning due to surface roughness.

Satellite Telemetry and Command using Big LEO Mobile Telecommunications Systems

Science.gov (United States)

Huegel, Fred

1998-01-01

Various issues associated with satellite telemetry and command using Big LEO mobile telecommunications systems are presented in viewgraph form. Specific topics include: 1) Commercial Satellite system overviews: Globalstar, ICO, and Iridium; 2) System capabilities and cost reduction; 3) Satellite constellations and contact limitations; 4) Capabilities of Globalstar, ICO and Iridium with emphasis on Globalstar; and 5) Flight transceiver issues and security.

LEO 1.0. An assistant software for maintenance of corroded reinforced concrete structures

International Nuclear Information System (INIS)

Gerard, B.; Petre-Lazar, I.

1998-04-01

The reinforced concrete structures capacity to fulfill the users requirements decreases in time and a constant preoccupation for the maintenance is required at EDF. In order to ease up the site investigations, a computer program - LEO - is developed. Its general layout is proposed in this document. LEO 1.0 is developed to be applied to corroded reinforced concrete structures. A simplified model based on the main mechanisms of the steel corrosion in concrete has been developed. It can quantify the influence of the reinforcement corrosion on the structure performances. A probabilistic calculus which takes into account the variability of the input data (material properties, environment, etc.) was also performed using PROBAN computer code. This type of analysis quantifies the time evolution of the structure (incubation, initiation, propagation, collapse). (author)

AVALIAÇÃO DO POTENCIAL FUNGITÓXICO DO ÓLEO ESSENCIAL DE Syzygium aromaticum(L. MERR & PERRY (CRAVO-DA-ÍNDIA

Directory of Open Access Journals (Sweden)

Milene Aparecida Andrade

2007-12-01

Full Text Available As plantas produzem uma variedade de compostos orgânicos. Muitos destes são conhecidos como metabólitos secundários, eestão relacionados com a interação da planta e o meio ambiente, como por exemplo, a defesa da planta contra insetos, bactérias efungos. Os óleos essenciais constituem um tipo de metabólito secundário de grande importância econômica, pois muitos podem serutilizados como medicamentos, inseticidas e antimicrobianos. O objetivo do presente trabalho foi verificar o potencial fungitóxico doóleo essencial de Syzygium aromaticum sobre fungos fitopatogênicos. O óleo essencial foi extraído dos botões florais secos,empregando a técnica de arraste a vapor de água, utilizando o aparelho de Clevenger modificado. A fungitoxicidade do óleo foiavaliada sobre Fusarium oxysporum e Rhizoctonia solani. Os testes foram realizados “in vitro”, observando-se o crescimento destesfitopatógenos, na presença de diferentes concentrações de óleo 100, 200, 500, 1000 e 2000mg/Kg, usando o meio de cultura BDA(Batata-Dextrose-Ágar. Os fungos foram incubados em câmara de germinação com controle de temperatura e luz, realizando-se 3repetições. Observou-se que o óleo essencial de Syzygium aromaticum reduziu o crescimento micelial de Fusarium oxysporum eRhizoctonia solani. A inibição do crescimento micelial (ICM ocorreu em todas as concentrações citadas acima, sendo que a partir de500mg/Kg ocorreu a inibição total dos fungos.

Anterior Overgrowth in Primary Curves, Compensatory Curves and Junctional Segments in Adolescent Idiopathic Scoliosis.

Science.gov (United States)

Schlösser, Tom P C; van Stralen, Marijn; Chu, Winnie C W; Lam, Tsz-Ping; Ng, Bobby K W; Vincken, Koen L; Cheng, Jack C Y; Castelein, René M

2016-01-01

Although much attention has been given to the global three-dimensional aspect of adolescent idiopathic scoliosis (AIS), the accurate three-dimensional morphology of the primary and compensatory curves, as well as the intervening junctional segments, in the scoliotic spine has not been described before. A unique series of 77 AIS patients with high-resolution CT scans of the spine, acquired for surgical planning purposes, were included and compared to 22 healthy controls. Non-idiopathic curves were excluded. Endplate segmentation and local longitudinal axis in endplate plane enabled semi-automatic geometric analysis of the complete three-dimensional morphology of the spine, taking inter-vertebral rotation, intra-vertebral torsion and coronal and sagittal tilt into account. Intraclass correlation coefficients for interobserver reliability were 0.98-1.00. Coronal deviation, axial rotation and the exact length discrepancies in the reconstructed sagittal plane, as defined per vertebra and disc, were analyzed for each primary and compensatory curve as well as for the junctional segments in-between. The anterior-posterior difference of spinal length, based on "true" anterior and posterior points on endplates, was +3.8% for thoracic and +9.4% for (thoraco)lumbar curves, while the junctional segments were almost straight. This differed significantly from control group thoracic kyphosis (-4.1%; P<0.001) and lumbar lordosis (+7.8%; P<0.001). For all primary as well as compensatory curves, we observed linear correlations between the coronal Cobb angle, axial rotation and the anterior-posterior length difference (r≥0.729 for thoracic curves; r≥0.485 for (thoraco)lumbar curves). Excess anterior length of the spine in AIS has been described as a generalized growth disturbance, causing relative anterior spinal overgrowth. This study is the first to demonstrate that this anterior overgrowth is not a generalized phenomenon. It is confined to the primary as well as the

Ge-on-Si : Single-Crystal Selective Epitaxial Growth in a CVD Reactor

NARCIS (Netherlands)

Sammak, A.; De Boer, W.B.; Nanver, L.K.

2012-01-01

A standard Si/SiGe ASM CVD reactor that was recently modified for merging GaAs and Si epitaxial growth in one system is utilized to achieve intrinsic and doped epitaxial Ge-on-Si with low threading dislocation and defect densities. For this purpose, the system is equipped with 2% diluted GeH4 as the

Mamona: determinação quantitativa do teor de óleo Quantitive determination of castor oil

Directory of Open Access Journals (Sweden)

Míriam Bottiglia Tambascia

1986-01-01

Full Text Available Foi desenvolvida uma metodologia para quantificar o teor de óleo em sementes de mamona, a partir da determinação do índice de refração de soluções etanólicas de diferentes concentrações a diferentes temperaturas. Os resultados mostraram um comportamento linear entre índice de refração e concentração de óleo para cada temperatura, com um excelente coeficiente de correlação, permitindo, assim, a quantificação do teor de óleo de mamona por metodologia bastante rápida e precisa.A methodology was developed to quantify the castor oil seed content, through the determination of refractive index of ethanolic solutions with different oil concentrations and temperatures. The results showed a nearly linear relationship between the refractive index and oil concentration for each temperature. This correlation permits to quantify castor oil content of ethanolic solutions by calculation from the quickly and accurate measurement of refractive index.

PROSPECÇÃO TECNOLÓGICA DE ÓLEO ESSENCIAL DE AROEIRA-DA-PRAIA (Schinus terebinthifolius Raddi.

Directory of Open Access Journals (Sweden)

Valéria Melo Mendonça

2014-03-01

Full Text Available A aroeira-da-praia (Schinusterebinthifolius Raddi. é uma espécie brasileira com grande importânciano cenário mundial por diversas características de interesse, dentre elas, oóleo essencial por seu valor fitoterápico. Com o intuito de verificarinformações sobre o uso do óleo essencial desta planta foi realizada umaprospecção em bancos de dados de pesquisa científica, tecnológica e de patentes.Existem muitos trabalhos acadêmicos sobre a aroeira-da-praia, mas poucos sobreóleo essência e número de depósito de patentes. Sendo assim, nota-se umadiscrepância entre o conhecimento acadêmico e o desenvolvimento tecnológico. Onúmero reduzido de patentes corrobora com o pouco registro de medicamentos efitoterápicos em órgãos de controle e certificação, como os Ministérios daSaúde e da Agricultura, e Vigilância Sanitária.

Control growth of silicon nanocolumns' epitaxy on silicon nanowires

Energy Technology Data Exchange (ETDEWEB)

Chong, Su Kong, E-mail: sukong1985@yahoo.com.my [University of Malaya, Low Dimensional Materials Research Centre, Department of Physics (Malaysia); Dee, Chang Fu [Universiti Kebangsaan Malaysia (UKM), Institute of Microengineering and Nanoelectronics (IMEN) (Malaysia); Yahya, Noorhana [Universiti Teknologi PETRONAS, Faculty of Science and Information Technology (Malaysia); Rahman, Saadah Abdul [University of Malaya, Low Dimensional Materials Research Centre, Department of Physics (Malaysia)

2013-04-15

The epitaxial growth of Si nanocolumns on Si nanowires was studied using hot-wire chemical vapor deposition. A single-crystalline and surface oxide-free Si nanowire core (core radius {approx}21 {+-} 5 nm) induced by indium crystal seed was used as a substance for the vapor phase epitaxial growth. The growth process is initiated by sidewall facets, which then nucleate upon certain thickness to form Si islands and further grow to form nanocolumns. The Si nanocolumns with diameter of 10-20 nm and aspect ratio up to 10 can be epitaxially grown on the surface of nanowires. The results showed that the radial growth rate of the Si nanocolumns remains constant with the increase of deposition time. Meanwhile, the radial growth rates are controllable by manipulating the hydrogen to silane gas flow rate ratio. The optical antireflection properties of the Si nanocolumns' decorated SiNW arrays are discussed in the text.

Silicon epitaxy on textured double layer porous silicon by LPCVD

International Nuclear Information System (INIS)

Cai Hong; Shen Honglie; Zhang Lei; Huang Haibin; Lu Linfeng; Tang Zhengxia; Shen Jiancang

2010-01-01

Epitaxial silicon thin film on textured double layer porous silicon (DLPS) was demonstrated. The textured DLPS was formed by electrochemical etching using two different current densities on the silicon wafer that are randomly textured with upright pyramids. Silicon thin films were then grown on the annealed DLPS, using low-pressure chemical vapor deposition (LPCVD). The reflectance of the DLPS and the grown silicon thin films were studied by a spectrophotometer. The crystallinity and topography of the grown silicon thin films were studied by Raman spectroscopy and SEM. The reflectance results show that the reflectance of the silicon wafer decreases from 24.7% to 11.7% after texturing, and after the deposition of silicon thin film the surface reflectance is about 13.8%. SEM images show that the epitaxial silicon film on textured DLPS exhibits random pyramids. The Raman spectrum peaks near 521 cm -1 have a width of 7.8 cm -1 , which reveals the high crystalline quality of the silicon epitaxy.

Molecular-beam epitaxy growth of high-performance midinfrared diode lasers

International Nuclear Information System (INIS)

Turner, G.W.; Choi, H.K.; Calawa, D.R.

1994-01-01

Recent advances in the performance of GaInAsSb/AlGaAsSb quantum-well diode lasers have been directly related to improvements in the quality of the molecular-beam epitaxy (MBE)-grown epitaxial layers. These improvements have been based on careful measurement and control of lattice matching and intentional strain, changes in shutter sequencing at interfaces, and a generally better understanding of the growth of Sb-based epitaxial materials. By using this improved MBE-grown material, significantly enhanced performance has been obtained for midinfrared lasers. These lasers, which are capable of ∼2-μm emission at room temperature, presently exhibit threshold current densities of 143 A/cm 2 , continuous wave powers of 1.3 W, and diffraction-limited powers of 120 mW. Such high-performance midinfrared diode lasers are of interest for a wide variety of applications, including eye-safe laser radar, remote sensing of atmospheric contaminants and wind turbulence, laser surgery, and pumping of solid-state laser media. 12 refs., 3 figs

The preparation of Zn-ferrite epitaxial thin film from epitaxial Fe3O4:ZnO multilayers by ion beam sputtering deposition

International Nuclear Information System (INIS)

Su, Hui-Chia; Dai, Jeng-Yi; Liao, Yen-Fa; Wu, Yu-Han; Huang, J.C.A.; Lee, Chih-Hao

2010-01-01

A new method to grow a well-ordered epitaxial ZnFe 2 O 4 thin film on Al 2 O 3 (0001) substrate is described in this work. The samples were made by annealing the ZnO/Fe 3 O 4 multilayer which was grown with low energy ion beam sputtering deposition. Both the Fe 3 O 4 and ZnO layers were found grown epitaxially at low temperature and an epitaxial ZnFe 2 O 4 thin film was formed after annealing at 1000 o C. X-ray diffraction shows the ZnFe 2 O 4 film is grown with an orientation of ZnFe 2 O 4 (111)//Al 2 O 3 (0001) and ZnFe 2 O 4 (1-10)//Al 2 O 3 (11-20). X-ray absorption spectroscopy studies show that Zn 2+ atoms replace the tetrahedral Fe 2+ atoms in Fe 3 O 4 during the annealing. The magnetic properties measured by vibrating sample magnetometer show that the saturation magnetization of ZnFe 2 O 4 grown from ZnO/Fe 3 O 4 multilayer reaches the bulk value after the annealing process.

Powder free PECVD epitaxial silicon by plasma pulsing or increasing the growth temperature

Science.gov (United States)

Chen, Wanghua; Maurice, Jean-Luc; Vanel, Jean-Charles; Cabarrocas, Pere Roca i.

2018-06-01

Crystalline silicon thin films are promising candidates for low cost and flexible photovoltaics. Among various synthesis techniques, epitaxial growth via low temperature plasma-enhanced chemical vapor deposition is an interesting choice because of two low temperature related benefits: low thermal budget and better doping profile control. However, increasing the growth rate is a tricky issue because the agglomeration of clusters required for epitaxy leads to powder formation in the plasma. In this work, we have measured precisely the time evolution of the self-bias voltage in silane/hydrogen plasmas at millisecond time scale, for different values of the direct-current bias voltage applied to the radio frequency (RF) electrode and growth temperatures. We demonstrate that the decisive factor to increase the epitaxial growth rate, i.e. the inhibition of the agglomeration of plasma-born clusters, can be obtained by decreasing the RF OFF time or increasing the growth temperature. The influence of these two parameters on the growth rate and epitaxial film quality is also presented.

Reduced defect densities in the ZnO epilayer grown on Si substrates by laser-assisted molecular-beam epitaxy using a ZnS epitaxial buffer layer

International Nuclear Information System (INIS)

Onuma, T.; Chichibu, S.F.; Uedono, A.; Yoo, Y.-Z.; Chikyow, T.; Sota, T.; Kawasaki, M.; Koinuma, H.

2004-01-01

Nonradiative photoluminescence (PL) lifetime (τ nr ) and point defect density in the (0001) ZnO epilayer grown on (111) Si substrates by laser-assisted molecular-beam epitaxy (L-MBE) using a (0001) ZnS epitaxial buffer layer were compared with those in the ZnO films on (111) and (001) Si substrates prepared by direct transformation of ZnS epilayers on Si by thermal oxidation [Yoo et al., Appl. Phys. Lett. 78, 616 (2001)]. Both the ZnO films exhibited excitonic reflectance anomalies and corresponding PL peaks at low temperature, and the density or size of vacancy-type point defects (Zn vacancies), which were measured by the monoenergetic positron annihilation measurement, in the L-MBE epilayer was lower than that in the films prepared by the oxidation transformation. The ZnO epilayer grown on a (0001) ZnS epitaxial buffer on (111) Si exhibited longer τ nr of 105 ps at room temperature

Cultivo intercalares em fase inicial de desenvolvimento e desempenho produtivo de cultivares de palma de óleo em diferentes ambientes de Roraima

OpenAIRE

Antonia Dianaia Oliveira Lopes

2014-01-01

A expansão da cultura da palma de óleo nas áreas já desflorestadas da Amazônia legal é reconhecida como uma excelente alternativa para a produção de óleo para fins alimentícios e energéticos. O estado de Roraima apresenta as condições edafoclimáticas adequadas para seu desenvolvimento e introdução na estrutura da agricultura familiar. Objetivou-se com este trabalho desenvolver sistemas de cultivos nas entrelinhas da palma de óleo em área de floresta alterada, durante o período inicial de dese...

Laser molecular beam epitaxy of ZnO thin films and heterostructures

International Nuclear Information System (INIS)

Opel, Matthias; Geprägs, Stephan; Althammer, Matthias; Brenninger, Thomas; Gross, Rudolf

2014-01-01

We report on the growth of epitaxial ZnO thin films and ZnO-based heterostructures on sapphire substrates by laser molecular beam epitaxy (MBE). We first discuss some recent developments in laser-MBE such as flexible ultraviolet laser beam optics, infrared laser heating systems or the use of atomic oxygen and nitrogen sources, and describe the technical realization of our advanced laser-MBE system. Then we describe the optimization of the deposition parameters for ZnO films such as laser fluence and substrate temperature and the use of buffer layers. The detailed structural characterization by x-ray analysis and transmission electron microscopy shows that epitaxial ZnO thin films with high structural quality can be achieved, as demonstrated by a small out-of-plane and in-plane mosaic spread as well as the absence of rotational domains. We also demonstrate the heteroepitaxial growth of ZnO-based multilayers as a prerequisite for spin transport experiments and the realization of spintronic devices. As an example, we show that TiN/Co/ZnO/Ni/Au multilayer stacks can be grown on (0 0 0 1)-oriented sapphire with good structural quality of all layers and well defined in-plane epitaxial relations. (paper)

Epitaxial YBa2Cu3O7-δ/Sr2RuO4 heterostructures

International Nuclear Information System (INIS)

Schlom, D.G.; Merritt, B.A.; Madhavan, S.

1997-01-01

The anisotropic oxide superconductors YBa 2 Cu 3 O 7-δ and Sr 2 RuO 4 have been epitaxially combined in various ways (c-axis on c-axis, c-axis on a-axis, and a-axis on a-axis) though the use of appropriate substrates. Phase-pure a-axis oriented or c-axis oriented epitaxial Sr 2 RuO 4 films were grown by pulsed laser deposition. YBa 2 Cu 3 O 7-δ films were then grown on both orientations of Sr 2 RuO 4 films and the resulting epitaxy was characterized

LEOS 2002: summer electronics and signal processing symposium

International Nuclear Information System (INIS)

Karadzhinov, Ljupcho; Ivanovski, Zoran

2002-01-01

LEOS 2002 was the first Macedonian symposium on electronics and signal processing. It was organized in recognition to a growing need to exchange the research results as well as to raise competent discussions among different research groups from both academic and industrial environment in Macedonia. The topics covered in this meeting were defined by the IEEE experts as follows: Power Electronics, Industrial Electronics, Signal Processing, Image and Video Processing, Instrumentation and Measurements, Engineering in Medicine and Biology, Electron Devices and Automatic Control. Papers were mainly from Macedonia, but there was one invited lecture

The science of 'man-eating' among lions Panthera Leo with a ...

African Journals Online (AJOL)

The story of the 'Man-eaters of Tsavo' has been retold through script, cinema, and oral tradition in the 100+ years since their infamous 'reign of terror'. Despite their predictably broad popular appeal, the details pertaining to the natural history of these lions Panthera leo have never been reviewed. The skulls and skins of ...

COMPOSIÇÃO QUÍMICA E AVALIAÇÃO DA ATIVIDADE CARRAPATICIDA DO ÓLEO ESSENCIAL DE Cinnamomun zeylanicum NO CONTROLE DE Rhipicephalus microplus

OpenAIRE

ILDENICE NOGUEIRA MONTEIRO

2013-01-01

Os constituintes do óleo de Cinnamomum zeylanicum foram identificados por cromatografia gasosa acoplada à espectrometria de massas (CG-EM). Também foi avaliada a atividade deste óleo essencial contra larvas e fêmeas de Rhipicephalus microplus (carrapato bovino). O óleo das folhas mostrou um rendimento de 1,03% e seus principais constituintes foram Benzoato de Benzila (65,39%), Linalol (5,37%), E-Cinamaldeido (3,97%), α-Pineno (3,95%), β-Felandreno (3,42%), Eugenol (3,36%) e Benzalde...

Layered growth model and epitaxial growth structures for SiCAlN alloys

International Nuclear Information System (INIS)

Liu Zhaoqing; Ni Jun; Su Xiaoao; Dai Zhenhong

2009-01-01

Epitaxial growth structures for (SiC) 1-x (AlN) x alloys are studied using a layered growth model. First-principle calculations are used to determine the parameters in the layered growth model. The phase diagrams of epitaxial growth are given. There is a rich variety of the new metastable polytype structures at x=1/6 ,1/5 ,1/4 ,1/3 , and 1/2 in the layered growth phase diagrams. We have also calculated the electronic properties of the short periodical SiCAlN alloys predicted by our layered growth model. The results show that various ordered structures of (SiC) 1-x (AlN) x alloys with the band gaps over a wide range are possible to be synthesized by epitaxial growth.

Consumo e Descarte do Óleo Comestível em um Município do sul de Minas Gerais/ Consumption and Disposal of Edible Oil in a city of Southern Minas Gerais

OpenAIRE

Patricia Calixto Novaes; Alexandre Magno Batista Machado; Fábio Vieira Lacerda

2014-01-01

Objetivo: Estimar a quantidade de óleo residual comercializado na cidade, tendo como amostras os grandes revendedores do produto, e estimar a quantidade de óleo destinada por meio dos ecopontos de coleta de óleo no município. Métodos: Foi coletada, em cinco estabelecimentos de referência na cidade, a quantidade de óleo que foi comercializada no ano de 2013, juntamente com a quantidade de óleo destinada para reaproveitamento. Os dados foram confrontados e discutidos seguindo as diretrizes da l...

Process for depositing an oxide epitaxially onto a silicon substrate and structures prepared with the process

Science.gov (United States)

McKee, Rodney A.; Walker, Frederick J.

1993-01-01

A process and structure involving a silicon substrate utilizes an ultra high vacuum and molecular beam epitaxy (MBE) methods to grow an epitaxial oxide film upon a surface of the substrate. As the film is grown, the lattice of the compound formed at the silicon interface becomes stabilized, and a base layer comprised of an oxide having a sodium chloride-type lattice structure grows epitaxially upon the compound so as to cover the substrate surface. A perovskite may then be grown epitaxially upon the base layer to render a product which incorporates silicon, with its electronic capabilities, with a perovskite having technologically-significant properties of its own.

Estabilidade oxidativa de óleos vegetais utilizados em frituras de mandioca palito congelada Oxidative stability of vegetable oils used in frozen cassava chips frying

Directory of Open Access Journals (Sweden)

Mara da Silva Corsini

2006-03-01

Full Text Available O presente estudo teve como objetivo determinar a medida da estabilidade oxidativa e a alteração total dos óleos de algodão, girassol e palma durante a fritura descontínua de mandioca palito congelada. As frituras foram conduzidas em uma fritadeira elétrica doméstica, onde o óleo foi aquecido, à temperatura de 180°C, por 25 h, com reposição de óleo fresco. Para a análise da estabilidade oxidativa das amostras de óleos, obtidas durante as frituras, foram realizadas a medida do período de indução (horas e determinação de compostos polares totais (%. Os resultados mostraram uma diminuição do período de indução, independente do tipo de óleo. O óleo de palma refinado apresentou um maior período de indução quando comparado ao óleo de algodão e girassol, o que pode ser atribuído à diferença da composição em ácidos graxos. Todos os óleos em estudo apresentaram valores de compostos polares totais abaixo do limite de descarte para óleos de fritura, exigido pela legislação internacional (24-27%. Verificou-se também que, à medida que se formaram os compostos de degradação, diminuiu a estabilidade oxidativa dos óleos.The present study aimed at determining the oxidative stability measurement and the total alteration of cotton, sunflower and palm oils during frozen cassava chips discontinued frying. The fryings were performed in a household electric frying pan, where the oil was heated up to 180°C temperature, for 25 h, with fresh oil replacement. For the oxidative stability analysis of the oil samples obtained during the fryings, were used the induction period (hours and total polar compounds determinations (%. The results showed a decrease in the induction period, regardless of the oil type. The refined palm oil presented a higher induction period when compared to the cotton and sunflower oils, which can be attributed to the fatty acids composition difference. All of the oils studied showed total polar

AVALIAÇÃO DO POTENCIAL FUNGITÓXICO DO ÓLEO ESSENCIAL DE Syzygium aromaticum (L. MERR & PERRY (CRAVO-DA-ÍNDIA

Directory of Open Access Journals (Sweden)

Maria da Graça Cardoso

2007-12-01

Full Text Available As plantas produzem uma variedade de compostos orgânicos. Muitos destes são conhecidos como metabólitos secundários, e estão relacionados com a interação da planta e o meio ambiente, como por exemplo, a defesa da planta contra insetos, bactérias e fungos. Os óleos essenciais constituem um tipo de metabólito secundário de grande importância econômica, pois muitos podem ser utilizados como medicamentos, inseticidas e antimicrobianos. O objetivo do presente trabalho foi verificar o potencial fungitóxico do óleo essencial de Syzygium aromaticum sobre fungos fitopatogênicos. O óleo essencial foi extraído dos botões florais secos, empregando a técnica de arraste a vapor de água, utilizando o aparelho de Clevenger modificado. A fungitoxicidade do óleo foi avaliada sobre Fusarium oxysporum e Rhizoctonia solani. Os testes foram realizados “in vitro”, observando-se o crescimento destes fitopatógenos, na presença de diferentes concentrações de óleo 100, 200, 500, 1000 e 2000mg/Kg, usando o meio de cultura BDA (Batata-Dextrose-Ágar. Os fungos foram incubados em câmara de germinação com controle de temperatura e luz, realizando-se 3 repetições. Observou-se que o óleo essencial de Syzygium aromaticum reduziu o crescimento micelial de Fusarium oxysporum e Rhizoctonia solani. A inibição do crescimento micelial (ICM ocorreu em todas as concentrações citadas acima, sendo que a partir de 500mg/Kg ocorreu a inibição total dos fungos

Seed layer technique for high quality epitaxial manganite films

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P. Graziosi

2016-08-01

Full Text Available We introduce an innovative approach to the simultaneous control of growth mode and magnetotransport properties of manganite thin films, based on an easy-to-implement film/substrate interface engineering. The deposition of a manganite seed layer and the optimization of the substrate temperature allows a persistent bi-dimensional epitaxy and robust ferromagnetic properties at the same time. Structural measurements confirm that in such interface-engineered films, the optimal properties are related to improved epitaxy. A new growth scenario is envisaged, compatible with a shift from heteroepitaxy towards pseudo-homoepitaxy. Relevant growth parameters such as formation energy, roughening temperature, strain profile and chemical states are derived.

Zirconia thin films from aqueous precursors: Processing, microstructural development, and epitaxial growth

International Nuclear Information System (INIS)

Miller, K.T.

1991-01-01

Thin films of ZrO 2 (Y 2 O 3 ) were prepared from aqueous salt precursors by spin coating. Films were pyrolyzed to produce porous polycrystalline thin films of 5-10 nm grain size. Subsequent microstructural development depends greatly upon the nature of the substrate. Upon randomly oriented sapphire, the films initially sintered to full density; further heat treatment and grain growth causes these films to break into interconnected islands and finally isolated particles. Thermodynamic calculations predict that breakup is energetically favorable when the grain-size film-thickness ratio exceeds a critical value. Upon basal-plane-oriented sapphire, grain growth and breakup prefer the (100) oriented grains, presumably because this orientation is a special interface of low energy. The isolated, oriented grains produced by film breakup act as seeds for the growth of newly deposited material. Upon (100) cubic zirconia, true epitaxial films develop. Epitaxial growth was observed for lattice mismatches up to 1.59%. Growth proceeds from a fine epitaxial layer which is produced during the initial stages of heat treatment, consuming the porous polycrystalline material and producing a dense epitaxial thin film whose misfit is accommodated by a combination of film strain and misfit dislocations

OBTENÇÃO DO BIODIESEL ATRAVÉS DA TRANSESTERIFICAÇÃO DO ÓLEO DE Moringa Oleífera Lam

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Daniele Silva Oliveira

2012-03-01

Full Text Available A Moringa Oleífera Lam é uma oleaginosa que tem um grande potencial para a produção de bicombustível no semi-árido nordestino, uma vez que se adapta a várias condições climáticas. A semente produz entre 35 % a 40 % de óleo. O objetivo desse trabalho foi obter o biodiesel através do processo de transesterificação e caracterizar as propriedades físico-químicas do óleo e biodiesel de acordo com as normas estabelecidas pela ANP. O biodiesel foi produzido pela rota metílica com o catalisador KOH. Os resultados mostraram que a semente de moringa produz óleo em boa quantidade com características físico-químicas adequadas para ser usado como matéria prima na transesterificação para obtenção de biodiesel. O teor de óleo médio encontrado para as sementes de moringa foi de 40 %, fornecendo rendimento de 83,68% em biodiesel e conversão dos ácidos graxos em ésteres metílicos de 99,9 %.

ÓLEO DE DENDÊ NA PRODUÇÃO DE BIODIESEL:UM ESTUDO DE CASO DAS VANTAGENS E DESVANTAGENS ECONÔMICA, ECOLÓGICA E SOCIAL DA CULTURA DESTA OLEAGINOSA PARA A PRODUÇÃO DE BIODIESEL.

OpenAIRE

Henkes, Jairo Afonso; Lebid, Taras

2015-01-01

O objetivo deste estudo é analisar as vantagens e desvantagens no campo econômico, social e ecológico da cultura do dendê (Elaeis guineensis) destinada à extração de óleo de palma e óleo de palmiste para produção do biodiesel. Conforme o Programa Nacional de Produção e Uso do Biodiesel (PNPB), o óleo diesel distribuído nos postos do Brasil possui em sua composição 6% de óleo vegetal e 94% de óleo diesel derivado do petróleo (B6) e esta mistura tende a crescer em percentual de óleo vegetal até...

Hard gap in epitaxial semiconductor-superconductor nanowires

DEFF Research Database (Denmark)

Chang, W.; Albrecht, S. M.; Jespersen, T. S.

2015-01-01

a continuum of subgap states---a situation that nullifies topological protection. Here, we report a hard superconducting gap induced by proximity effect in a semiconductor, using epitaxial Al-InAs superconductor-semiconductor nanowires. The hard gap, along with favorable material properties and gate...

Petróleo y cambio social como programa de investigación en Venezuela

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Luis J. González Oquendo

2006-01-01

Full Text Available Alo largo del siglo xx, el petróleo ha sido el elemento estructural que ha explicado la estructuración de la sociedad venezolana. Es una idea extendida que Venezuela es lo que la actividad petrolera le ha permitido ser. El presente trabajo se está interesado en estudiar cómo la construcción de la sociedad venezolana ha sido posible desde la óptica de productos intelectuales científico sociales. No interesa sólo una lectura teórica sino hacer una aproximación epistemológica que determine la existencia de un programa de investigación. Se utilizó el modelo VIE de José Padrón para analizar la obra de cinco científicos sociales clave que han estudiado el impacto social del petróleo en Venezuela: Rodolfo Quintero, Carmen Vallarino de Bracho, Roberto Briceño León, María Sol Pérez Schael y Fernando Coronil. Finalmente, se pudo demostrar que el único elemento en común entre estos estudios de investigación es el objeto, aunque cada uno de ellos tiene diferentes construcciones teóricas acerca de éste. De este modo, «petróleo y cambio social en Venezuela» no es todavía un programa de investigación

Royalties do petróleo e emprego público nos municípios Brasileiros

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Lauro Carnicelli

2014-09-01

Full Text Available O objetivo deste artigo é investigar se as transferências do petróleo (royalties e participações especiais levaram as prefeituras beneficiadas a aumentar a contratação de funcionários públicos, em desacordo com as recomendações legais. Para isto, aplicou-se o método Duplamente Robusto a um painel de municípios observados entre 2000 e 2009. O método compõe-se de dois estágios. Primeiramente, estimaram-se as probabilidades de recepção de receitas do petróleo condicionadas a variáveis observáveis; em um segundo estágio, estimou-se um painel de efeitos fixos no conjunto de observações pertencentes a um suporte comum construído a partir dos propensity scores estimados no primeiro estágio. Os resultados mostram que as prefeituras elevam o seu quadro de funcionários diante do usufruto de rendas do petróleo, mas a despesa média com pessoal não aumenta nas cidades pertencentes ao grupo de tratamento. No Rio de Janeiro, sujeito a determinações mais específicas de seu Tribunal de Contas, o efeito não é significativo, indicando a aderência das prefeituras às regras.

The influence of Fe doping on the surface topography of GaN epitaxial material

International Nuclear Information System (INIS)

Cui Lei; Yin Haibo; Jiang Lijuan; Wang Quan; Feng Chun; Xiao Hongling; Wang Cuimei; Wang Xiaoliang; Gong Jiamin; Zhang Bo; Li Baiquan; Wang Zhanguo

2015-01-01

Fe doping is an effective method to obtain high resistivity GaN epitaxial material. But in some cases, Fe doping could result in serious deterioration of the GaN material surface topography, which will affect the electrical properties of two dimensional electron gas (2DEG) in HEMT device. In this paper, the influence of Fe doping on the surface topography of GaN epitaxial material is studied. The results of experiments indicate that the surface topography of Fe-doped GaN epitaxial material can be effectively improved and the resistivity could be increased after increasing the growth rate of GaN materials. The GaN material with good surface topography can be manufactured when the Fe doping concentration is 9 × 10 19 cm −3 . High resistivity GaN epitaxial material which is 1 × 10 9 Ω·cm is achieved. (paper)

MgO monolayer epitaxy on Ni (100)

Science.gov (United States)

Sarpi, B.; Putero, M.; Hemeryck, A.; Vizzini, S.

2017-11-01

The growth of two-dimensional oxide films with accurate control of their structural and electronic properties is considered challenging for engineering nanotechnological applications. We address here the particular case of MgO ultrathin films grown on Ni (100), a system for which neither crystallization nor extended surface ordering has been established previously in the monolayer range. Using Scanning Tunneling Microscopy and Auger Electron Spectroscopy, we report on experiments showing MgO monolayer (ML) epitaxy on a ferromagnetic nickel surface, down to the limit of atomic thickness. Alternate steps of Mg ML deposition, O2 gas exposure, and ultrahigh vacuum thermal treatment enable the production of a textured film of ordered MgO nano-domains. This study could open interesting prospects for controlled epitaxy of ultrathin oxide films with a high magneto-resistance ratio on ferromagnetic substrates, enabling improvement in high-efficiency spintronics and magnetic tunnel junction devices.

Epitaxial Garnets and Hexagonal Ferrites.

Science.gov (United States)

1982-04-20

guide growth of the epitaxial YIG films. Aluminum or gallium substitu- tions for iron were used in combination with lanthanum substitutions for yttrium... gallate spinel sub- strates. There was no difficulty with nucleation in the melt and film quality appeared to be similar to that observed previously...hexagonal ferrites. We succeeded in growing the M-type lead hexaferrite (magnetoplumbite) on gallate spinel substrates. We found that the PbO-based

Scalable solution-phase epitaxial growth of symmetry-mismatched heterostructures on two-dimensional crystal soft template.

Science.gov (United States)

Lin, Zhaoyang; Yin, Anxiang; Mao, Jun; Xia, Yi; Kempf, Nicholas; He, Qiyuan; Wang, Yiliu; Chen, Chih-Yen; Zhang, Yanliang; Ozolins, Vidvuds; Ren, Zhifeng; Huang, Yu; Duan, Xiangfeng

2016-10-01

Epitaxial heterostructures with precisely controlled composition and electronic modulation are of central importance for electronics, optoelectronics, thermoelectrics, and catalysis. In general, epitaxial material growth requires identical or nearly identical crystal structures with small misfit in lattice symmetry and parameters and is typically achieved by vapor-phase depositions in vacuum. We report a scalable solution-phase growth of symmetry-mismatched PbSe/Bi 2 Se 3 epitaxial heterostructures by using two-dimensional (2D) Bi 2 Se 3 nanoplates as soft templates. The dangling bond-free surface of 2D Bi 2 Se 3 nanoplates guides the growth of PbSe crystal without requiring a one-to-one match in the atomic structure, which exerts minimal restriction on the epitaxial layer. With a layered structure and weak van der Waals interlayer interaction, the interface layer in the 2D Bi 2 Se 3 nanoplates can deform to accommodate incoming layer, thus functioning as a soft template for symmetry-mismatched epitaxial growth of cubic PbSe crystal on rhombohedral Bi 2 Se 3 nanoplates. We show that a solution chemistry approach can be readily used for the synthesis of gram-scale PbSe/Bi 2 Se 3 epitaxial heterostructures, in which the square PbSe (001) layer forms on the trigonal/hexagonal (0001) plane of Bi 2 Se 3 nanoplates. We further show that the resulted PbSe/Bi 2 Se 3 heterostructures can be readily processed into bulk pellet with considerably suppressed thermal conductivity (0.30 W/m·K at room temperature) while retaining respectable electrical conductivity, together delivering a thermoelectric figure of merit ZT three times higher than that of the pristine Bi 2 Se 3 nanoplates at 575 K. Our study demonstrates a unique epitaxy mode enabled by the 2D nanocrystal soft template via an affordable and scalable solution chemistry approach. It opens up new opportunities for the creation of diverse epitaxial heterostructures with highly disparate structures and functions.

Graphene nanoribbons epitaxy on boron nitride

Energy Technology Data Exchange (ETDEWEB)

Lu, Xiaobo; Wang, Shuopei; Wu, Shuang; Chen, Peng; Zhang, Jing; Zhao, Jing; Meng, Jianling; Xie, Guibai; Wang, Duoming; Wang, Guole; Zhang, Ting Ting; Yang, Rong; Shi, Dongxia [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Yang, Wei [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Laboratoire Pierre Aigrain, ENS-CNRS UMR 8551, Universités Pierre et Marie Curie and Paris-Diderot, 24 rue Lhomond, 75231 Paris Cedex 05 (France); Watanabe, Kenji; Taniguchi, Takashi [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Zhang, Guangyu, E-mail: gyzhang@aphy.iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100190 (China)

2016-03-14

In this letter, we report a pilot study on epitaxy of monolayer graphene nanoribbons (GNRs) on hexagonal boron nitride (h-BN). We found that GNRs grow preferentially from the atomic steps of h-BN, forming in-plane heterostructures. GNRs with well-defined widths ranging from ∼15 nm to ∼150 nm can be obtained reliably. As-grown GNRs on h-BN have high quality with a carrier mobility of ∼20 000 cm{sup 2} V{sup −1} s{sup −1} for ∼100-nm-wide GNRs at a temperature of 1.7 K. Besides, a moiré pattern induced quasi-one-dimensional superlattice with a periodicity of ∼15 nm for GNR/h-BN was also observed, indicating zero crystallographic twisting angle between GNRs and h-BN substrate. The superlattice induced band structure modification is confirmed by our transport results. These epitaxial GNRs/h-BN with clean surfaces/interfaces and tailored widths provide an ideal platform for high-performance GNR devices.

Controle pós-colheita da antracnose do maracujazeiro: amarelo com aplicação de óleo de copaíba

Directory of Open Access Journals (Sweden)

Sebastião Elviro de Araújo Neto

2014-06-01

Full Text Available O objetivo deste trabalho foi avaliar a aplicação de óleo essencial de copaíba no controle da antracnose, nos frutos do maracujazeiro-amarelo, e comparar sua ação fungicida/fungistática in vitro com o óleo resina de copaíba. No experimento in vivo, os frutos foram inoculados com uma suspensão de esporos da ordem de 10(6 conídios mL-1 e 1% de Tween 80, acondicionados em bandejas de polipropileno e colocados em câmara incubadora com temperatura de 25ºC e 90% de umidade relativa do ar. Passadas 24 horas da inoculação, pulverizou-se óleo essencial nas seguintes concentrações: T1= 0 mL L-1; T2= 0,25 mL L-1; T3= 0,5 mL L-1; T4= 0,75 mL L-1; T5= 1,0 mL L-1, sendo avaliados a perda de massa do fruto, a severidade da antracnose e o número de lesões, ambas aos seis dias. Para o experimento in vitro, utilizou-se do meio de cultura batata-dextrose-ágar (BDA que, após ser esterilizado em autoclave (120 ºC, recebeu óleo essencial e óleo resina de copaíba (0; 0,5; 1,0; 1,5 e 2,0 mL L-1. Após o resfriamento do meio de cultura, foi repicado para o centro da placa um disco de micélio de 12,5 mm de diâmetro de Colletotrichum gloeosporioides; e as placas, incubadas a 25ºC e 90% de umidade. A aferição do crescimento micelial foi verificada com o auxílio de paquímetro analógico, após sete dias de crescimento micelial. O óleo essencial de copaíba, nas concentrações de 0,25 mL L-1 a 1.0 mL L-1, não foi eficaz no controle pós-colheita do fungo da antracnose in vivo e na perda de massa dos frutos de maracujá. O óleo resina de copaíba inibiu o crescimento de C. gloeosporioides in vitro de forma mais eficiente que o óleo essencial de copaíba.

Surface Chemistry Involved in Epitaxy of Graphene on 3C-SiC(111/Si(111

Directory of Open Access Journals (Sweden)

Abe Shunsuke

2010-01-01

Full Text Available Abstract Surface chemistry involved in the epitaxy of graphene by sublimating Si atoms from the surface of epitaxial 3C-SiC(111 thin films on Si(111 has been studied. The change in the surface composition during graphene epitaxy is monitored by in situ temperature-programmed desorption spectroscopy using deuterium as a probe (D2-TPD and complementarily by ex situ Raman and C1s core-level spectroscopies. The surface of the 3C-SiC(111/Si(111 is Si-terminated before the graphitization, and it becomes C-terminated via the formation of C-rich (6√3 × 6√3R30° reconstruction as the graphitization proceeds, in a similar manner as the epitaxy of graphene on Si-terminated 6H-SiC(0001 proceeds.

Epitaxial growth of semiconducting β-FeSi2 and its application to light-emitting diodes

International Nuclear Information System (INIS)

Suemasu, T.; Takakura, K.; Li, Cheng; Ozawa, Y.; Kumagai, Y.; Hasegawa, F.

2004-01-01

In this paper, we review the detailed study of epitaxial growth of β-FeSi 2 films by reactive deposition epitaxy (RDE), multilayer technique and molecular beam epitaxy (MBE). The p- and n-type β-FeSi 2 was formed when it was grown under an Fe-rich and an Si-rich condition, respectively. The maximum electron and hole mobilities of the β-FeSi 2 epitaxial films reached 6900 and 13000 cm 2 /V·s for the n- and p-type β-FeSi 2 , respectively, at around 50 K. Room temperature (RT) 1.6 μm electroluminescence (EL) was realized by optimizing the growth conditions for p-Si/β-FeSi 2 particles/n-Si structures prepared by RDE for β-FeSi 2 and by MBE for Si

Variáveis hematológicas em tambaquis anestesiados com óleo de cravo e benzocaína

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Santiago Benites de Pádua

2013-08-01

Full Text Available O objetivo deste trabalho foi avaliar o efeito anestésico de óleo de cravo e benzocaína sobre os parâmetros hematológicas e a fragilidade osmótica dos eritrócitos em tambaqui (Colossoma macropomum. Trinta peixes adultos foram avaliados em três tratamentos: controle, sem anestesia; anestesia com óleo de cravo a 50 mg L-1; e anestesia com benzocaína a 100 mg L-1. O sangue dos peixes foi coletado para a determinação do hemograma, e o teste de fragilidade osmótica dos eritrócitos foi aplicado. As doses utilizadas de óleo de cravo e benzocaína não são adequadas para estudos hematológicos, para estabelecer valores de referência em tambaquis, pois causam alterações expressivas dos parâmetros hematológicos, tais como leucocitose e hemólise iatrogênica.

Adição de óleo de palma na dieta sobre a lipidemia e a qualidade do sêmen de bubalinos (Bubalus bubalis

Directory of Open Access Journals (Sweden)

G.R. Silva

2014-02-01

Full Text Available O estudo visou investigar o efeito da suplementação dietética com óleo de palma sobre o perfil sérico lipídico e as características seminais de touros bubalinos (Bubalus bubalis, bem como suas correlações. Doze touros foram alocados no Grupo CONT (n=5 ou Grupo ÓLEO (n=7 e receberam alimentação isoproteica composta por silagem de milho e concentrado (milho triturado, farelo de trigo e ureia, com proporção volumoso/concentrado de 50%, durante 130 dias (Períodos 1 e 2. Diferencialmente, óleo de palma foi adicionado ao concentrado (2% MS do Grupo ÓLEO. Sêmen e sangue foram colhidos quinzenalmente. Houve aumento nas concentrações séricas de colesterol, HDL e lipídios totais nos animais do Grupo ÓLEO, enquanto o período influenciou nas taxas de colesterol, LDL, lipídios totais e VLDL (P<0,05. Houve decréscimo no turbilhonamento e discreta redução na integridade de membranas nos animais do Grupo ÓLEO (P<0,05. Correlações significativas foram encontradas entre triglicerídeos e defeitos menores (r=-0,412; P=0,006, LDL e defeitos totais (r=-0,333; P=0,030, lipídios totais e defeitos menores (r=-0.366; P= 0,017, lipídios totais e defeitos totais (r=-0.309; P= 0,046, e VLDL e viabilidade espermática (r=0,381; P=0,012, apontando efeitos positivos da maior lipidemia na morfologia e na viabilidade espermática. O uso de óleo de palma alterou o perfil lipídico sérico, mas não favoreceu per se os parâmetros seminais relacionados com o potencial de fertilidade dos touros.

Strain and crystalline defects in epitaxial GaN layers studied by high-resolution X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Chierchia, Rosa

2007-07-01

This thesis treats strain and dislocations in MOVPE GaN layers. The mosaic structure of metalorganic vapour phase epitaxy (MOVPE)-grown GaN layers was studied in dependence on the grain diameter utilizing high-resolution XRD. Different models for the defect structure were analyzed, the edge type TD densities were calculated under the assumption that the dislocations are not randomly distributed but localized at the grain boundaries. Moreover, in situ measurements have shown that the layers are under tension in the c-plane when a nucleation layer is used. The second part of this thesis treats a particular approach to reduce dislocations in MOVPE GaN layers, i.e. maskless pendeo epitaxial growth of MOVPE GAN layers. FE simulations assuming the strain to be completely induced during cooling of the structures after growth agree only partly with experimental data. The strain state of single layers and stripes of GaN grown on SiC was studied to exploit the evolution of the strain in the different phases of the PE growth. The biaxial compressive stress, due to the lattice mismatch between the GaN layer and the AlN nucleation layer is plastically relieved before overgrowth. Temperature dependent measurements show a linear reduction of the wing tilt with increasing temperature varying from sample to sample. Bent TDs have been observed in TEM images of maskless PE samples. Stress induced from the mismatch between the AlN buffer layer and the GaN also contributes to the remaining part of the wing tilt not relieved thermally. It has to be noted that the rest tilt value varies from sample to sample at the growth temperature. In fact some of the data indicate that the wing tilt decreases with increasing V/III ratio. In the last Chapter the application of X-ray techniques for the analysis of strain and composition in layers of inhomogeneous composition is explored. In the first part of the Chapter the strain state and the Al content of AlGaN buffer layers grown directly on (0001

Epitaxial growth of zinc on ferritic steel under high current density electroplating conditions

International Nuclear Information System (INIS)

Greul, Thomas; Comenda, Christian; Preis, Karl; Gerdenitsch, Johann; Sagl, Raffaela; Hassel, Achim Walter

2013-01-01

Highlights: •EBSD of electroplated Zn on Fe or steel was performed. •Zn grows epitaxially on electropolished ferritic steel following Burger's orientation relation. •Surface deformation of steel leads to multiple electroplated zinc grains with random orientation. •Zn grows epitaxially even on industrial surfaces with little surface deformation. •Multiple zinc grains on one steel grain can show identical orientation relations. -- Abstract: The dependence of the crystal orientation of electrodeposited zinc of the grain orientation on ferritic steel substrate at high current density deposition (400 mA cm −2 ) during a pulse-plating process was investigated by means of EBSD (electron backscatter diffraction) measurements. EBSD-mappings of surface and cross-sections were performed on samples with different surface preparations. Furthermore an industrial sample was investigated to compare lab-coated samples with the industrial process. The epitaxial growth of zinc is mainly dependent on the condition of the steel grains. Deformation of steel grains leads to random orientation while zinc grows epitaxially on non-deformed steel grains even on industrial surfaces

LEOPACK The integrated services communications system based on LEO satellites

Science.gov (United States)

Negoda, A.; Bunin, S.; Bushuev, E.; Dranovsky, V.

LEOPACK is yet another LEO satellite project which provides global integrated services for 'business' communications. It utilizes packet rather then circuit switching in both terrestrial and satellite chains as well as cellular approach for frequencies use. Original multiple access protocols and decentralized network control make it possible to organize regionally or logically independent and world-wide networks. Relatively small number of satellites (28) provides virtually global network coverage.

Adsorption-controlled growth of BiMnO3 films by molecular-beam epitaxy

International Nuclear Information System (INIS)

Lee, J. H.; Ke, X.; Misra, R.; Schiffer, P.; Ihlefeld, J. F.; Mei, Z. G.; Liu, Z. K.; Xu, X. S.; Musfeldt, J. L.; Heeg, T.; Schlom, D. G.; Roeckerath, M.; Schubert, J.

2010-01-01

We have developed the means to grow BiMnO 3 thin films with unparalleled structural perfection by reactive molecular-beam epitaxy and determined its band gap. Film growth occurs in an adsorption-controlled growth regime. Within this growth window bounded by oxygen pressure and substrate temperature at a fixed bismuth overpressure, single-phase films of the metastable perovskite BiMnO 3 may be grown by epitaxial stabilization. X-ray diffraction reveals phase-pure and epitaxial films with ω rocking curve full width at half maximum values as narrow as 11 arc sec (0.003 deg. ). Optical absorption measurements reveal that BiMnO 3 has a direct band gap of 1.1±0.1 eV.

CARACTERIZAÇÃO E AVALIAÇÃO DA ATIVIDADE LARVICIDA DO ÓLEO ESSENCIAL DO Zingiber officinale Roscoe (GENGIBRE) FRENTE AO MOSQUITO Aedes aegypti

OpenAIRE

ANDRESON LEANDRO SANTANA SILVA

2012-01-01

Na procura pelo controle químico alternativo contra o mosquito Aedes aegypti, diversas pesquisas são desenvolvidas e estimuladas no intuito de descobrirem novas substâncias inseticidas de origem vegetal. Neste trabalho a partir da extração e do estudo analítico do óleo essencial dos rizomas do Zingiber officinale Roscoe, foi analisado o efeito larvicida do óleo contra larvas em terceiro estágio do mosquito Aedes aegypti (Linnaeus, 1792). Extraiu-se quantitativamente o óleo essencial por hidro...

Estudo do escoamento imiscível água/óleo mediante experimentação em célula de Hele-Shaw e simulação CFD

OpenAIRE

Mariano, Gabriel Cassemiro

2008-01-01

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Química O estudo de sistemas água-óleo é de fundamental importância para diversos processos industriais. Procedimentos como a recuperação secundária de petróleo e o bombeamento de óleos de viscosidade elevada, mediante a injeção conjunta de água, exemplificam situações na indústria petrolífera em que o comportamento da interface água-óleo traz importantes conseqüênci...

ALTERAÇÕES DO ÓLEO DE SOJA EM FRITURA DESCONTÍNUA DE PRODUTOS EMPANADOS CONGELADOS EM UMA UNIDADE DE ALIMENTAÇÃO E NUTRIÇÃO

Directory of Open Access Journals (Sweden)

Fabiele WITSCHINSKI

2012-08-01

Full Text Available O objetivo do presente estudo foi avaliar as alterações e o nível de degradação de óleo de soja utilizado em processo de fritura descontínuo de produtos empanados congelados (risóles, croquetes, coxinhas e pastéis em uma Unidade de Alimentação e Nutrição. Durante o processo de fritura descontínua (com e sem reposição de óleo, coletouse amostras de óleo de soja periodicamente a fim de avaliar a estabilidade oxidativa (Acidez total, Índice de peróxido e do ácido tiobarbitúrico TBARS e de cor. Na fritura de produtos empanados congelados observou que a acidez do óleo de soja aumentou gradativamente com o tempo de fritura, atingindo 0,9 % de ácido oleico com 6,7 horas de fritura no lote com reposição de óleo e 6,2 horas no lote sem reposição, respectivamente. No entanto, o grau de rancidez hidrolítica (hidroperóxidos e malonaldeido e o escurecimento do óleo foi mais acentuada após 10 horas de processamento, perdendo luminosidade (brancura, predominando a cor mais intensa para amarelo e com teores de peróxidos e malonaldeído superiores a 9 mEq.Kg-1 e 0,49 mg de malonaldeído.Kg-1, respectivamente. O grau das alterações no óleo de soja, submetido à fritura descontínua, variou principalmente em função de características dos produtos empanados congelados (tamanho das porções, atividade de água dos alimentos e quantidade de partículas sólidas e da reposição ou não de óleo durante o processamento, sendo que o período máximo de utilização do óleo foi de aproximadamente 10 horas.

Epitaxy, thin films and superlattices

International Nuclear Information System (INIS)

Jagd Christensen, Morten

1997-05-01

This report is the result of structural investigations of 3d transition metal superlattices consisting of Fe/V, Cr/Mn, V/Mn and Fe/Mn, and a structural and magnetic study of a series of Ho/Pr alloys. The work includes preparation and characterization of substrates as well as growth of thin films and Fe/V superlattices by molecular beam epitaxy, including in-situ characterization by reflection high energy electron diffraction and Auger electron spectroscopy. Structural characterization has been done by x-ray diffraction and neutron diffraction. The x-ray diffraction experiments have been performed on the rotating copper anode at Risoe, and at synchrotron facilities in Hamburg and Brookhaven, and the neutron scattering was done at the Danish research reactor DR3 at Risoe. In addition to longitudinal scans, giving information about the structural parameters in the modulation direction, non-specular scans were also performed. This type of scans gives information about in-plane orientation and lattice parameters. From the analysis, structural information is obtained about lattice parameters, epitaxial strain, coherence lengths and crystallographic orientation for the superlattice systems, except Fe/Mn superlattices, which could not be modelled. For the Ho/Pr alloys, x-ray magnetic scattering was performed, and the crystal and magnetic structure was investigated. (au)

Epitaxy, thin films and superlattices

Energy Technology Data Exchange (ETDEWEB)

Jagd Christensen, Morten

1997-05-01

This report is the result of structural investigations of 3d transition metal superlattices consisting of Fe/V, Cr/Mn, V/Mn and Fe/Mn, and a structural and magnetic study of a series of Ho/Pr alloys. The work includes preparation and characterization of substrates as well as growth of thin films and Fe/V superlattices by molecular beam epitaxy, including in-situ characterization by reflection high energy electron diffraction and Auger electron spectroscopy. Structural characterization has been done by x-ray diffraction and neutron diffraction. The x-ray diffraction experiments have been performed on the rotating copper anode at Risoe, and at synchrotron facilities in Hamburg and Brookhaven, and the neutron scattering was done at the Danish research reactor DR3 at Risoe. In addition to longitudinal scans, giving information about the structural parameters in the modulation direction, non-specular scans were also performed. This type of scans gives information about in-plane orientation and lattice parameters. From the analysis, structural information is obtained about lattice parameters, epitaxial strain, coherence lengths and crystallographic orientation for the superlattice systems, except Fe/Mn superlattices, which could not be modelled. For the Ho/Pr alloys, x-ray magnetic scattering was performed, and the crystal and magnetic structure was investigated. (au) 14 tabs.; 58 ills., 96 refs.

Laboratory Instrumentation Design Research for Scalable Next Generation Epitaxy: Non-Equilibrium Wide Application Epitaxial Patterning by Intelligent Control (NEW-EPIC). Volume 1. 3D Composition/Doping Control via Micromiror Patterned Deep UV Photodesorption: Revolutionary in situ Characterization/Control

Science.gov (United States)

2009-02-19

34 (to be submitted to APL) " Positron Annihilation Spectroscopy of Annealed and As-grown Be-doped GaN" (to be submitted to APL - delayed by the...WIDE APPLICATION EPITAXIAL PATTERNING BY INTELLIGENT CONTROL (NEW-EPIC) 6. AUTHOR(S) DRS DOOLITTILE, FRAZIER, BURNHAM, PRITCHETT, BILLINGSLEY...NEXT GENERATION EPITAXY: NON-EQUILIBRIUM WIDE APPLICATION EPITAXIAL PATTERNING BY INTELLIGENT CONTROL (NEW-EPIC) VOLUME I 3D COMPOSITION/DOPING

Composição e fungitoxicidade do óleo essencial de capim citronela em função da adubação orgânica

Directory of Open Access Journals (Sweden)

Ronice Alves Veloso

2012-12-01

Full Text Available O objetivo deste trabalho foi avaliar a influência da adubação orgânica sobre o teor e a composição do óleo essencial de capim citronela (Cymbopogon nardus, bem como a fungitoxicidade desse óleo ao crescimento micelial dos fungos Didymella bryoniae, Colletotrichum gloeosporioides e Amphobotrys ricini. A extração do óleo essencial foi realizada por hidrodestilação, a partir de plantas cultivadas em quatro doses de adubação orgânica (0, 3, 6 e 9 kg de esterco bovino curtido por cova, e a identificação dos constituintes químicos foi conduzida por cromatografia gasosa/espectrometria de massas. Para avaliar a inibição do crescimento micelial, o experimento foi instalado no delineamento inteiramente casualizado, em arranjo fatorial. Foram testadas sete alíquotas do óleo essencial (0, 5, 10, 15, 20, 25 e 30 µL, em cinco épocas de avaliação, com quatro repetições. O teor de óleo essencial do capim citronela não foi afetado pela adubação orgânica, e o óleo essencial do capim citronela apresentou 24 compostos químicos, entre estes monoterpenos e sesquiterpenos, com maior concentração dos compostos citronelal, β-citronelol, geraniol e elemol. O óleo essencial do capim citronela apresenta maior efeito de inibição a Amphobotrys ricini, em comparação aos fungos Didymella bryoniae e Colletotrichum gloeosporioides.

Transfer-free electrical insulation of epitaxial graphene from its metal substrate.

Science.gov (United States)

Lizzit, Silvano; Larciprete, Rosanna; Lacovig, Paolo; Dalmiglio, Matteo; Orlando, Fabrizio; Baraldi, Alessandro; Gammelgaard, Lauge; Barreto, Lucas; Bianchi, Marco; Perkins, Edward; Hofmann, Philip

2012-09-12

High-quality, large-area epitaxial graphene can be grown on metal surfaces, but its transport properties cannot be exploited because the electrical conduction is dominated by the substrate. Here we insulate epitaxial graphene on Ru(0001) by a stepwise intercalation of silicon and oxygen, and the eventual formation of a SiO(2) layer between the graphene and the metal. We follow the reaction steps by X-ray photoemission spectroscopy and demonstrate the electrical insulation using a nanoscale multipoint probe technique.

Transfer-Free Electrical Insulation of Epitaxial Graphene from its Metal Substrate

DEFF Research Database (Denmark)

Lizzit, Silvano; Larciprete, Rosanna; Lacovig, Paolo

2012-01-01

High-quality, large-area epitaxial graphene can be grown on metal surfaces, but its transport properties cannot be exploited because the electrical conduction is dominated by the substrate. Here we insulate epitaxial graphene on Ru(0001) by a stepwise intercalation of silicon and oxygen......, and the eventual formation of a SiO2 layer between the graphene and the metal. We follow the reaction steps by X-ray photoemission spectroscopy and demonstrate the electrical insulation using a nanoscale multipoint probe technique....

Pseudomorphic growth of organic semiconductor thin films driven by incommensurate epitaxy

International Nuclear Information System (INIS)

Sassella, A.; Campione, M.; Raimondo, L.; Borghesi, A.; Bussetti, G.; Cirilli, S.; Violante, A.; Goletti, C.; Chiaradia, P.

2009-01-01

A stable pseudomorphic phase of α-quaterthiophene, a well known organic semiconductor, is obtained by growing films with organic molecular beam epitaxy (OMBE) on a single crystal of another organic semiconductor, namely, tetracene. The structural characteristics of the new phase are investigated by monitoring in situ the OMBE process by reflectance anisotropy spectroscopy; thus assessing that incommensurate epitaxy is in this case, the driving force for tuning the molecular packing in organic molecular films and in turn, their solid state properties

IMPACTO DEL PETRÓLEO CRUDO EN SUELO SOBRE LA MICROBIOTA DE VIDA LIBRE FIJADORA DE NITRÓGENO

Directory of Open Access Journals (Sweden)

Mayra Vázquez-Luna

2011-11-01

Full Text Available Los derrames de petróleo afectan las propiedades físicas del suelo y especialmente las poblaciones naturales de microorganismos. En particular causan disminución en bacterias fijadoras de nitrógeno de vida libre, encargadas de asimilar y reciclar nutrientes en los ciclos biogeoquímicos; al alterarse éstos, se afecta la fertilidad del suelo. El objetivo de esta investigación fue evaluar el impacto del petróleo crudo sobre bacterias fijadoras de nitrógeno de vida libre en un suelo bajo condiciones controladas. Se experimentó en suelo contaminado con cinco concentraciones de petróleo (1200, 3500, 10,000, 20,000 y 40,000 mg kg-1 en peso seco en un diseño completamente al azar. Se midieron las poblaciones bacterias fijadoras de nitrógeno de vida libre en cada concentración. El índice del impacto microbiano de las bacterias mostró que al final de la prueba (219 h, en cada una de las cinco concentraciones de petróleo hubo un incremento exponencial de colonias bacterianas altamente significativo (P ≤ 0.01, 2 a 3.5 veces más abundantes que en el testigo. Se infiere un fenómeno de recolonización y adaptación al medio. A nivel macroscópico, en los tratamientos con mayor concentración de petróleo hubo menor diversidad de colonias, pero las poblaciones fueron significativamente mayores. También, en los tratamientos de mayor concentración del hidrocarburo, se observaron colonias bacterianas no presentes en el tratamiento testigo. Las bacterias fijadoras de nitrógeno de vida libre podrían adaptarse a condiciones adversas. La selección de las más aptas sería útil en la biorremediación o saneamiento de zonas impactadas por petróleo crudo.

Efeito fungitóxico in vitro do óleo resina e do óleo essencial de copaíba (Copaifera multijuga Hayne In vitro fungitoxic effect of the oil-resin and the essential oil of copaiba (Copaifera multijuga Hayne

Directory of Open Access Journals (Sweden)

R.J.A. Deus

2009-01-01

Full Text Available Óleo de Copaifera multijuga Hayne, in natura e as frações foram avaliadas quanto às atividades fungitóxicas in vitro, frente a cinco espécies de fungos filamentosos do gênero Aspergillus e três espécies de leveduras do gênero Candida. Concentrações de óleo resina e de óleo essencial na faixa de 0,08 mg mL-1 a 1,6 mg mL-1 foram usadas para as análises qualitativa e quantitativas. As amostras foram dispostas sobre discos de papel de 5 mm de diâmetro e distribuídos sobre o meio Saboraud em placas de Petri, inoculadas com esporos dos microorganismos e incubadas a 28ºC durante 10 dias. Utilizou-se solução com 1,6 mg mL-1 de nitrato de miconazol como controle positivo. Os resultados qualitativos mostraram que o óleo resina apresentou boa atividade fungistática, porém uma das frações do óleo essencial se mostrou altamente efetiva contra Candida parapsilosis IOC-2882, Aspergillus flavus IOC-3874 e A tamarii IOC-187 com halos de inibição de 16,0±1,4 mm, 19,5±2,1 mm e 12,5±3,5 mm, respectivamente. Já a avaliação quantitativa mostrou que 0,3 mg mL-1 do óleo resina inibiu o crescimento de A. flavus e C. parapsilosis, enquanto que 0,08 mg mL-1 da fração do óleo essencial atingiu esta mesma atividade.Copaifera multijuga Hayne oil, crude and fractions, was evaluated for its in vitro fungitoxic activities against five species of filamentous fungi belonging to the genus Aspergillus and three yeast species of the genus Candida. Oil-resin and essential oil concentrations ranging from 0.008 mg mL-1 to 1.6 mg mL-1 were used in qualitative and quantitative analyses. Samples were placed onto 5mm-diameter paper disks and distributed on Saboraud culture medium in Petri dishes inoculated with conidia and incubated at 28ºC during 10 days. A solution with 1.6 mg mL-1 of miconazole nitrate was used as positive control. Qualitative results indicated that the oil-resin presented good fungistatic activity; however, one of the essential

Avaliação do efeito antifúngico do óleo resina e do óleo essencial de copaíba (Copaifera multijuga Hayne Evaluation of the antifungal effect of oleoresin and essential oil of copaiba (Copaifera multijuga Hayne

Directory of Open Access Journals (Sweden)

R.J.A Deus

2011-01-01

Full Text Available Óleo de Copaifera multijuga Hayne, in natura e as frações foram avaliados quanto às suas atividades fungitóxicas, frente a cinco espécies de fungos filamentosos do gênero Aspergillus e três espécies de leveduras do gênero Candida. Concentrações de óleo resina e de óleo essencial na faixa de 0,08 mg mL-1a 1,6 mg mL-1 foram usadas para as análises qualitativa e quantitativas. As amostras foram dispostas sobre discos de papel de 5 mm de diâmetro e distribuídos sobre o meio Saboraud em placas de Petri, inoculadas com esporos dos microrganismos e incubadas a 28ºC durante 10 dias. Utilizou-se uma solução com 1,6 mg mL-1 de nitrato de miconazol como controle positivo. Os resultados qualitativos mostraram que o óleo resina apresentou boa atividade, porém uma das frações do óleo essencial se mostrou altamente efetivo contra C. parapsilosis IOC - 2882, A.flavus IOC-3874 e A. tamarii IOC-187 com halos de inibição de 16,0±1,4 mm, 19,5±2,1 mm e 12,5±3,5 mm, respectivamente. Já a avaliação quantitativa mostrou que 0,3 mg mL-1 do óleo resina inibiu o crescimento de A. flavus e C. parapsilosis, enquanto que 0,08 mg mL-1 da fração do óleo essencial atingiu esta mesma atividade.Copaifera multijuga Hayne oil in natura and its fractions were evaluated as to their fungitoxic activities against five filamentous fungus species belonging to the genus Aspergillus and three yeast species of the genus Candida. Oleoresin and essential oil concentrations ranging from 0.08 mg mL-1 to 1.6 mg mL-1 were used for qualitative and quantitative analyses. The samples were placed onto 5mm-diameter paper discs distributed on Sabouraud's medium in Petri dishes inoculated with spores of the microorganisms and incubated at 28ºC for 10 days. A solution containing 1.6 mg mL-1 miconazole nitrate was used as positive control. Qualitative results showed that the oleoresin presented good activity, while a fraction of the essential oil was highly effective

Sizing of "Mother Ship and Catcher" Missions for LEO Small Debris and for GEO Large Object Capture

Science.gov (United States)

Bacon, John B.

2009-01-01

Most LEO debris lies in a limited number of inclination "bands" associated with specific useful orbits. Objects in such narrow inclination bands have all possible Right Ascensions of Ascending Node (RAANs), creating a different orbit plane for nearly every piece of debris. However, a low-orbiting satellite will always phase in RAAN faster than debris objects in higher orbits at the same inclination, potentially solving the problem. Such a low-orbiting base can serve as a "mother ship" that can tend and then send small, disposable common individual catcher/deboost devices--one for each debris object--as the facility drifts into the same RAAN as each higher object. The dV necessary to catch highly-eccentric orbit debris in the center of the band alternatively allows the capture of less-eccentric debris in a wider inclination range around the center. It is demonstrated that most LEO hazardous debris can be removed from orbit in three years, using a single LEO launch of one mother ship--with its onboard magazine of freeflying low-tech catchers--into each of ten identified bands, with second or potentially third launches into only the three highest-inclination bands. The nearly 1000 objects near the geostationary orbit present special challenges in mass, maneuverability, and ultimate disposal options, leading to a dramatically different architecture and technology suite than the LEO solution. It is shown that the entire population of near-GEO derelict objects can be gathered and tethered together within a 3 year period for future scrap-yard operations using achievable technologies and only two earth launches.

Bromine doping of CdTe and CdMnTe epitaxial layers grown by molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Waag, A. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Scholl, S. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Schierstedt, K. von (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Hommel, D. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Landwehr, G. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Bilger, G. (Zentrum fuer Sonnenenergie und Wasserstoff-Forschung, Stuttgart (Germany))

1993-03-01

We report on the n-type doping of CdTe and CdMnTe with bormine as a novel dopant material. /the thin films were grown by molecular beam epitaxy. ZnBr[sub 2] was used as a source material for the n-type doping. Free carrier concentrations at room temperature of up to 2.8x10[sup 18] cm[sup -3] could be readily obtained for both CdTe as well as CdMnTe thin films with Mn concentrations below 10%. This is to our knowledge the highest value ever obtained for the dilute magnetic semiconductor CdMnTe. For ZnBr[sub 2] source temperatures up to 60 C - corresponding to a free carrier concentration of (2-3)x10[sup 18] cm[sup -3] - the free carrier concentration of the epitaxial film increases with ZnBr[sub 2] source temperature. For higher ZnBr[sub 2] source temperatures compensation becomes dominant, which is indicated by a steep decrease of the free carrier concentration with increasing ZnBr[sub 2] source temperature. In addition the carrier mobility decreases drastically for such high dopant fluxes. A model of bromine incorporation is proposed. (orig.)

Epitaxial growth and characterization of CuGa2O4 films by laser molecular beam epitaxy

Directory of Open Access Journals (Sweden)

Hongling Wei

2017-11-01

Full Text Available Ga2O3 with a wide bandgap of ∼ 4.9 eV can crystalize in five crystalline phases. Among those phases, the most stable monoclinic β-Ga2O3 has been studied most, however, it is hard to find materials lattice matching with β-Ga2O3 to grown epitaxial thin films for optoelectronic applications. In this work, CuGa2O4 bulk were prepared by solid state reaction as target, and the films were deposited on sapphire substrates by laser molecular beam epitaxy (L-MBE at different substrate temperatures. The influences of substrate temperature on structural and optical properties have been systematically investigated by means of X-ray diffraction, Transmission electron microscope and UV-vis absorption spectra. High quality cubic structure and [111] oriented CuGa2O4 film can be obtained at substrate temperature of 750 °C. It’s also demonstrated that the CuGa2O4 film has a bandgap of ∼ 4.4 eV and a best crystal quality at 750 °C, suggesting that CuGa2O4 film is a promising candidate for applications in ultraviolet optoelectronic devices.

The Role of Intestinal Bacteria Overgrowth in Obesity-Related Nonalcoholic Fatty Liver Disease

Directory of Open Access Journals (Sweden)

Silvia M. Ferolla

2014-12-01

Full Text Available Nonalcoholic fatty liver disease (NAFLD is the most common chronic liver disease worldwide. It is a progressive disorder involving a spectrum of conditions that include pure steatosis without inflammation, nonalcoholic steatohepatitis (NASH, fibrosis and cirrhosis. The key factor in the pathophysiology of NAFLD is insulin resistance that determines lipid accumulation in the hepatocytes, which may be followed by lipid peroxidation, production of reactive oxygen species and consequent inflammation. Recent studies suggest that the characteristics of the gut microbiota are altered in NAFLD, and also, that small intestinal bacterial overgrowth (SIBO contributes to the pathogenesis of this condition. This review presents the chief findings from all the controlled studies that evaluated SIBO, gut permeability and endotoxemia in human NAFLD. We also discuss the possible mechanisms involving SIBO, lipid accumulation and development of NASH. The understanding of these mechanisms may allow the development of new targets for NASH treatment in the future.

Quasi van der Waals epitaxy of copper thin film on single-crystal graphene monolayer buffer

Science.gov (United States)

Lu, Zonghuan; Sun, Xin; Washington, Morris A.; Lu, Toh-Ming

2018-03-01

Quasi van der Waals epitaxial growth of face-centered cubic Cu (~100 nm) thin films on single-crystal monolayer graphene is demonstrated using thermal evaporation at an elevated substrate temperature of 250 °C. The single-crystal graphene was transferred to amorphous (glass) and crystalline (quartz) SiO2 substrates for epitaxy study. Raman analysis showed that the thermal evaporation method had minimal damage to the graphene lattice during the Cu deposition. X-ray diffraction and electron backscatter diffraction analyses revealed that both Cu films are single-crystal with (1 1 1) out-of-plane orientation and in-plane Σ3 twin domains of 60° rotation. The crystallinity of the SiO2 substrates has a negligible effect on the Cu crystal orientation during the epitaxial growth, implying the strong screening effect of graphene. We also demonstrate the epitaxial growth of polycrystalline Cu on a commercial polycrystalline monolayer graphene consisting of two orientation domains offset 30° to each other. It confirms that the crystal orientation of the epitaxial Cu film follows that of graphene, i.e. the Cu film consists of two orientation domains offset 30° to each other when deposited on polycrystalline graphene. Finally, on the contrary to the report in the literature, we show that the direct current and radio frequency flip sputtering method causes significant damage to the graphene lattice during the Cu deposition process, and therefore neither is a suitable method for Cu epitaxial growth on graphene.

Epitaxial growth of a methoxy-functionalized quaterphenylene on alkali halide surfaces

Energy Technology Data Exchange (ETDEWEB)

Balzer, F., E-mail: fbalzer@mci.sdu.dk [University of Southern Denmark, Mads Clausen Institute, Alsion 2, DK-6400 Sønderborg (Denmark); Sun, R. [University of Southern Denmark, Mads Clausen Institute, Alsion 2, DK-6400 Sønderborg (Denmark); Parisi, J. [University of Oldenburg, Energy and Semiconductor Research Laboratory, Institute of Physics, Carl-von-Ossietzky-Str. 9-11, D-26111 Oldenburg (Germany); Rubahn, H.-G. [University of Southern Denmark, Mads Clausen Institute, Alsion 2, DK-6400 Sønderborg (Denmark); Lützen, A. [University of Bonn, Kekulé Institute of Organic Chemistry and Biochemistry, Gerhard-Domagk-Str. 1, D-53121 Bonn (Germany); Schiek, M. [University of Oldenburg, Energy and Semiconductor Research Laboratory, Institute of Physics, Carl-von-Ossietzky-Str. 9-11, D-26111 Oldenburg (Germany)

2015-12-31

The epitaxial growth of the methoxy functionalized para-quaterphenylene (MOP4) on the (001) faces of the alkali halides NaCl and KCl and on glass is investigated by a combination of low energy electron diffraction (LEED), polarized light microscopy (PLM), atomic force microscopy (AFM), and X-ray diffraction (XRD). Both domains from upright molecules as well as fiber-like crystallites from lying molecules form. Neither a wetting layer from lying molecules nor widespread epitaxial fiber growth on the substrates is detected. Our results focus on the upright standing molecules, which condense into a thin film phase with an enlarged layer spacing compared to the bulk phase. - Highlights: • Growth of a methoxy-functionalized para-phenylene on dielectric surfaces is investigated. • Low-energy electron diffraction and X-ray diffraction techniques are employed for structural characterization. • Epitaxial growth of upright molecules only is documented. • Polarized optical microscopy together with atomic force microscopy complements the findings.

Epitaxial growth of a methoxy-functionalized quaterphenylene on alkali halide surfaces

International Nuclear Information System (INIS)

Balzer, F.; Sun, R.; Parisi, J.; Rubahn, H.-G.; Lützen, A.; Schiek, M.

2015-01-01

The epitaxial growth of the methoxy functionalized para-quaterphenylene (MOP4) on the (001) faces of the alkali halides NaCl and KCl and on glass is investigated by a combination of low energy electron diffraction (LEED), polarized light microscopy (PLM), atomic force microscopy (AFM), and X-ray diffraction (XRD). Both domains from upright molecules as well as fiber-like crystallites from lying molecules form. Neither a wetting layer from lying molecules nor widespread epitaxial fiber growth on the substrates is detected. Our results focus on the upright standing molecules, which condense into a thin film phase with an enlarged layer spacing compared to the bulk phase. - Highlights: • Growth of a methoxy-functionalized para-phenylene on dielectric surfaces is investigated. • Low-energy electron diffraction and X-ray diffraction techniques are employed for structural characterization. • Epitaxial growth of upright molecules only is documented. • Polarized optical microscopy together with atomic force microscopy complements the findings.

Quantum Nanostructures by Droplet Epitaxy

OpenAIRE

Somsak Panyakeow

2009-01-01

Droplet epitaxy is an alternative growth technique for several quantum nanostructures. Indium droplets are distributed randomly on GaAs substrates at low temperatures (120-350'C). Under background pressure of group V elements, Arsenic and Phosphorous, InAs and InP nanostructures are created. Quantum rings with isotropic shape are obtained at low temperature range. When the growth thickness is increased, quantum rings are transformed to quantum dot rings. At high temperature range, anisotropic...

Charge collection properties of heavily irradiated epitaxial silicon detectors

International Nuclear Information System (INIS)

Kramberger, G.; Cindro, V.; Dolenc, I.; Fretwurst, E.; Lindstroem, G.; Mandic, I.; Mikuz, M.; Zavrtanik, M.

2005-01-01

Detectors processed on epitaxial silicon seem to be a viable solution for the extreme radiation levels in the innermost layers of tracking detectors at upgraded LHC (SLHC). A set of epitaxial pad detectors of 50 and 75μm thicknesses (ρ=50Ωcm) was irradiated with 24GeV/c protons and reactor neutrons up to equivalent fluences of 10 16 cm -2 . Charge collection for minimum ionizing electrons from a 90 Sr source was measured using a charge sensitive preamplifier and a 25ns shaping circuit. The dependence of collected charge on annealing time and operation temperature was studied. Results were used to predict the performance of fine pitch pixel detectors proposed for SLHC

Charge collection properties of heavily irradiated epitaxial silicon detectors

Energy Technology Data Exchange (ETDEWEB)

Kramberger, G. [Institute Jozef Stefan, Jamova 39, SI-1111 Ljubljana (Slovenia)]. E-mail: Gregor.Kramberger@ijs.si; Cindro, V. [Institute Jozef Stefan, Jamova 39, SI-1111 Ljubljana (Slovenia); Dolenc, I. [Institute Jozef Stefan, Jamova 39, SI-1111 Ljubljana (Slovenia); Fretwurst, E. [University of Hamburg, Institut fuer Experimentalphysik, Luruper Chaussee 149, D-22761 Hamburg (Germany); Lindstroem, G. [University of Hamburg, Institut fuer Experimentalphysik, Luruper Chaussee 149, D-22761 Hamburg (Germany); Mandic, I. [Institute Jozef Stefan, Jamova 39, SI-1111 Ljubljana (Slovenia); Mikuz, M. [Institute Jozef Stefan, Jamova 39, SI-1111 Ljubljana (Slovenia); Zavrtanik, M. [Institute Jozef Stefan, Jamova 39, SI-1111 Ljubljana (Slovenia)

2005-12-01

Detectors processed on epitaxial silicon seem to be a viable solution for the extreme radiation levels in the innermost layers of tracking detectors at upgraded LHC (SLHC). A set of epitaxial pad detectors of 50 and 75{mu}m thicknesses ({rho}=50{omega}cm) was irradiated with 24GeV/c protons and reactor neutrons up to equivalent fluences of 10{sup 16}cm{sup -2}. Charge collection for minimum ionizing electrons from a {sup 90}Sr source was measured using a charge sensitive preamplifier and a 25ns shaping circuit. The dependence of collected charge on annealing time and operation temperature was studied. Results were used to predict the performance of fine pitch pixel detectors proposed for SLHC.

Otimização da síntese de ésteres metílicos e etílicos a partir de óleo de dendê

OpenAIRE

Jhonatan Luiz Fiorio

2014-01-01

Atualmente o óleo de soja é o mais utilizado para a produção de biodiesel, porém tem se buscado oleaginosas que possam suprir a demanda de óleo, dentre essas o dendê pode ser um possível substituto, devido ao rendimento em óleo ser superior ao da soja. Com o objetivo de obter ésteres metílicos e etílicos a partir do óleo de dendê, foram conduzidas reações de transesterificação por metanólise e etanólise, utilizando catálise homogênea com metóxido de sódio (CH3ONa) e etóxido de sódio (CH3CH2ON...

ANÁLISE DE SUPERFÍCIE DE RESPOSTA DOS BLENDS DO ÓLEO DE MAMONA E BABAÇU

OpenAIRE

Francisco Francielle Pinheiro dos Santos; Francisca Diva Lima Almeida; Francisco de Assis da Silva Mota; Maria Alexsandra de Sousa Rios; Auceliane André da Silva Lima

2014-01-01

A mamona, (Ricinus communis L.), é uma planta oleaginosa que tem recebido grande destaque no programa brasileiro de biodiesel. O Programa fez a opção pelo plantio da mamona devido as suas características de cultivo, adaptação a múltiplos tipos de solo e características da gestão familiar. No entanto, devido a sua elevada viscosidade, o óleo de mamona tem sido cada vez mais descartado do cenário brasileiro da produção de biodiesel, sendo assim, torna-se necessário a mistura (blends) deste óleo...

EXTRAÇÃO E CARACTERIZAÇÃO DO ÓLEO ESSENCIAL DE MELALEUCA E DESENVOLVIMENTO DE UMA FORMULAÇÃO SEMI-SÓLIDA DE USO TÓPICO

Directory of Open Access Journals (Sweden)

Marcielli Indiara de Oliveira

2015-06-01

Full Text Available As plantas medicinais são bastante conhecidas e muito utilizadas pela maioria da população, sendo empregada em diversas finalidades na culinária, perfumaria, aromaterapia, para tratar e prevenir doenças, bem como no desenvolvimento de novos produtos. A espécie Melaleuca alternifolia, é uma planta rica em um óleo essencial com uma poderosa ação antimicrobiana e antifúngica. O objetivo desse trabalho é realizar a extração do óleo essencial da melaleuca e avaliar sua composição química, bem como desenvolver uma formulação semi-sólida de uso tópico para a incorporação do óleo. O óleo foi extraído por arraste a vapor, utilizando-se de um aparelho do tipo Clevenger nos tempos de 4 e 6 horas e sua composição química foi avaliada por cromatografia gasosa acoplada ao espectrômetro de massas (CG/MS. Após obtenção do óleo, o mesmo foi incorporado na formulação e avaliada sua estabilidade preliminar e acelerada. O rendimento do óleo extraído foi de 0,82% para 4 horas e 1,59% para 6 horas. Através das análises cromatográficas foi possível obter um perfil do óleo extraído, encontrando os compostos α – terpineno, γ- terpineno, ρ – cimeno, terpinen-4-ol, 1,8 – cineol como majoritários. Após incorporação do óleo de melaleuca (4% na pomada, a formulação foi aprovada nos estudos conduzidos quanto aos critérios de cor, odor, aspecto e pH.

Epitaxial GaN around ZnO nanopillars

Energy Technology Data Exchange (ETDEWEB)

Fikry, Mohamed; Scholz, Ferdinand [Institut fuer Optoelektronik, Universitaet Ulm, Albert-Einstein-Allee 45, 89081 Ulm (Germany); Madel, Manfred; Tischer, Ingo; Thonke, Klaus [Institut fuer Quantenmaterie, Universitaet Ulm, Albert-Einstein-Allee 45, 89081 Ulm (Germany)

2011-07-01

We report on an investigation of the epitaxial quality of GaN layers overgrown coaxially around ZnO nanopillars. In a first step, regularly arranged ZnO nanopillars were grown using pre-patterning by e-beam lithography or self-organized hexagonal polystyrene sphere masks. Alternatively, ZnO pillars were also successfully grown on top of GaN pyramids. In a second step, GaN layers were grown around the ZnO pillars by Metal Organic Vapor Phase Epitaxy. At growth temperatures above 800 C, the ZnO pillars are dissolved by the hydrogen carrier gas leaving hollow GaN nanotubes. Characterization involved photoluminescence (PL), scanning electron microscopy and cathodoluminescence. The fair quality of the deposited GaN layers is confirmed by a sharp low temperature PL peak at 3.48 eV attributed to the donor bound exciton emission. Further peaks at 3.42 eV and 3.29 eV show the possible existence of basal plane and prismatic stacking faults.

Epitaxial growth of thin single-crystals and their quality study by Rutherford scattering in channeling conditions

International Nuclear Information System (INIS)

Kirsch, Robert.

1975-01-01

Some aspects of thin crystalline layers are reminded: vacuum deposition, epitaxial growth, annealing and interdiffusion ion channeling and scattering of 1-2MeV helium ions are used to study the crystalline quality, the annealing effects and in some cases the interdiffusion in epitaxial multilayers of silver, copper gold and nickel. Thin single-crystals of gold and nickel oriented (III) plan parallel to the surface were obtained by successive epitaxial growth from muscovite mica clivages. The mounting techniques of single crystalline, self-supporting, 300 to 1200 Angstroems thick, gold and nickel targets of 3mm diameter are described. The gold single-crystals have dislocation densities of 10 8 cm -2 and the various epitaxial layers are obtained without twinning [fr

Epitaxial growth of silicon and germanium on (100-oriented crystalline substrates by RF PECVD at 175 °C

Directory of Open Access Journals (Sweden)

Mauguin O.

2012-11-01

Full Text Available We report on the epitaxial growth of crystalline Si and Ge thin films by standard radio frequency plasma enhanced chemical vapor deposition at 175 °C on (100-oriented silicon substrates. We also demonstrate the epitaxial growth of silicon films on epitaxially grown germanium layers so that multilayer samples sustaining epitaxy could be produced. We used spectroscopic ellipsometry, Raman spectroscopy, transmission electron microscopy and X-ray diffraction to characterize the structure of the films (amorphous, crystalline. These techniques were found to provide consistent results and provided information on the crystallinity and constraints in such lattice-mismatched structures. These results open the way to multiple quantum-well structures, which have been so far limited to few techniques such as Molecular Beam Epitaxy or MetalOrganic Chemical Vapor Deposition.

Epitaxial Integration of Nanowires in Microsystems by Local Micrometer Scale Vapor Phase Epitaxy

DEFF Research Database (Denmark)

Mølhave, Kristian; Wacaser, Brent A.; Petersen, Dirch Hjorth

2008-01-01

deposition (CVD) or metal organic VPE (MOVPE). However, VPE of semiconducting nanowires is not compatible with several microfabrication processes due to the high synthesis temperatures and issues such as cross-contamination interfering with the intended microsystem or the VPE process. By selectively heating...... a small microfabricated heater, growth of nanowires can be achieved locally without heating the entire microsystem, thereby reducing the compatibility problems. The first demonstration of epitaxial growth of silicon nanowires by this method is presented and shows that the microsystem can be used for rapid...

Actividade antimicrobiana do óleo essencial do Foeniculum vulgare Miller Antimicrobial activity of Foeniculum vulgare Miller essential oil

OpenAIRE

M. T. Tinoco; M. R. Martins; J. Cruz-Morais

2007-01-01

O Foeniculum vulgare Mill. subsp. vulgare é uma planta espontânea da região mediterrânea, pertencente à família Apiaceae. O seu óleo essencial, principalmente o dos frutos secos, é amplamente utilizado nas indústrias alimentar, farmacêutica, cosmética e perfumaria. Neste trabalho, pretendeu-se avaliar a actividade antimicrobiana do óleo essencial dos frutos verdes e das folhas da variedade de funcho doce colhido no Alentejo, na região de Évora, e relacionar essa actividade com a respectiva co...

Uso de óleo de aroeira-vermelha sobre o desempenho e a morfometria intestinal de frangos de corte

OpenAIRE

Silva,Maria Aparecida da; Pessotti,Bruna Mirelly de Sousa; Zanini,Surama Freitas; Colnago,Geraldo Luiz; Nunes,Louisiane de Carvalho; Rodrigues,Maria Regina Alves; Ferreira,Larissa

2010-01-01

Avaliou-se a utilização do óleo essencial extraído dos frutos de aroeira-vermelha (Schinus terebinthifolius Raddi) na dieta de frangos de corte sobre o desempenho e a morfometria intestinal. Utilizaram-se 240 pintos de um dia de idade, machos, da linhagem Cobb, distribuídos em delineamento inteiramente casualizado em grupos de cinco tratamentos e quatro repetições: sem antibiótico e anticoccidiano (controle negativo); com antibiótico e anticoccidiano (controle positivo); com 0,1% de óleo de a...

In silico carbon molecular beam epitaxial growth of graphene on the h-BN substrate: carbon source effect on van der Waals epitaxy

Science.gov (United States)

Lee, Jonghoon; Varshney, Vikas; Park, Jeongho; Farmer, Barry L.; Roy, Ajit K.

2016-05-01

Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon molecular beam epitaxy (CMBE) techniques using solid carbon sublimation have reported relatively poor quality of the graphene. In this article, the CMBE growth of graphene on the h-BN substrate is numerically studied in order to identify the effect of the carbon source on the quality of the graphene film. The carbon molecular beam generated by the sublimation of solid carbon source materials such as graphite and glassy carbon is mostly composed of atomic carbon, carbon dimers and carbon trimers. Therefore, the graphene film growth becomes a complex process involving various deposition characteristics of a multitude of carbon entities. Based on the study of surface adsorption and film growth characteristics of these three major carbon entities comprising graphite vapour, we report that carbon trimers convey strong traits of vdW epitaxy prone to high quality graphene growth, while atomic carbon deposition is a surface-reaction limited process accompanied by strong chemisorption. The vdW epitaxial behaviour of carbon trimers is found to be substantial enough to nucleate and develop into graphene like planar films within a nanosecond of high flux growth simulation, while reactive atomic carbons tend to impair the structural integrity of the crystalline h-BN substrate upon deposition to form an amorphous interface between the substrate and the growing carbon film. The content of reactive atomic carbons in the molecular beam is suspected to be the primary cause of low quality graphene reported in the literature. A possible optimization of the molecular beam composition towards the synthesis of better quality graphene films is suggested.Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon

Mass savings domain of plasma propulsion for LEO to GEO transfer

International Nuclear Information System (INIS)

Choueiri, E.Y.; Kelly, A.J.; Jahn, R.G.

1993-01-01

A parametric model is used to study the mass savings of plasma propulsion over advanced chemical propulsion for lower earth orbit (LEO) to geosynchronous orbit (GEO) transfer. Such savings are characterized by stringent requirements of massive payloads (O(10) metric tons) and high power levels (O(100) kW). Mass savings on the order of the payload mass are possible but at the expense of longer transfer times (8--20 months). Typical of the savings domain is the case of a self-field magnetoplasmadynamic (MPD) thruster running quasi-steadily, at an I s of 2000 s, with 600 kW of input power, raising a 50 metric ton satellite in 270 days. The initial mass at LEO will be 65 tons less than a 155 ton LO 2 /LH 2 advanced chemical high thrust spacecraft. An optimum I s can only be found if the cost savings associated with mass savings are counterbalanced by the cost losses incurred by longer transfer times. A simplistic cost model that illustrates the overall trends in the optimization yielded an optimum I s of about 2200 s for a cost effective baseline MPD system

TEM characterization of catalyst- and mask-free grown GaN nanorods

International Nuclear Information System (INIS)

Schowalter, M; Aschenbrenner, T; Kruse, C; Hommel, D; Rosenauer, A

2010-01-01

Catalyst- and mask-free grown GaN nanorods have been investigated using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and energy filtered transmission electron microscopy (EFTEM). The nanorods were grown on nitridated r-plane sapphire substrates in a molecular beam epitaxy reactor. We investigated samples directly after the nitridation and after the overgrowth of the structure with GaN. High resolution transmission electron microscopy (HRTEM) and EFTEM revealed that AlN islands have formed due to nitridation. After overgrowth, the AlN islands could not be observed any more, neither by EFTEM nor by Z-contrast imaging. Instead, a smooth layer consisting of AlGaN was found. The investigation of the overgrown sample revealed that an a-plane GaN layer and GaN nanorods on top of the a-plane GaN have formed. The nanorods reduced from top of the a-plane GaN towards the a-plane GaN/sapphire interface suggesting that the nanorods originate at the AlN islands found after nitridation. However, this could not be shown unambiguously. The number of threading dislocations in the nanorods was very low. The analysis of the epitaxial relationship to the a-plane GaN showed that the nanorods grew along the [000-1] direction, and the [1-100] direction of the rods was parallel to the [0001] direction of the a-plane GaN.

Análise química por CG-EM e toxicidade do óleo essencial de Ocimumselloi Benth. e estragol para Spodoptera frugiperda e Zabrotes subfasciatus

OpenAIRE

Menezes, Claubert Wagner Guimarães de

2015-01-01

A espécie Ocimum selloi Benth. (Lamiaceae) possui constituintes químicos em seu óleo essencial com ação inseticida. Objetivou-se avaliar o efeito inseticida por ingestão e por fumigação do óleo essencial de O. selloie do estragol sobre Spodoptera frugiperda(Smith, 1797) (Lepidoptera: Noctuidae)eo efeito por fumigação do óleo essencial sobreZabrotes subfasciatus(Bohemann, 1833) (Coleoptera, Bruchidae). No primeiro experimento, larvas de 48 horas d...

Changes in lion (Panthera leo) home range size in Waza National Park, Cameroon

NARCIS (Netherlands)

Tumenta, P.N.; Van't Zelfde, M.; Croes, B.M.; Buij, R.; Funston, P.J.; Haes, de H.A.U.; longh, De H.H.

2013-01-01

The spatial ecology of Africa lions (Panthera leo) was studied from 2007 to 2009 in Waza National Park, Cameroon, by equipping individual lions with GPS/VHF radio-collars. Mean home range estimates using 100% minimum convex polygons (MCP) and 95% kernel-density estimation (KDE) were respectively

A Parametric Study on Using Active Debris Removal for LEO Environment Remediation

Science.gov (United States)

2010-01-01

Recent analyses on the instability of the orbital debris population in the low Earth orbit (LEO) region and the collision between Iridium 33 and Cosmos 2251 have reignited the interest in using active debris removal (ADR) to remediate the environment. There are; however, monumental technical, resource, operational, legal, and political challenges in making economically viable ADR a reality. Before a consensus on the need for ADR can be reached, a careful analysis of its effectiveness must be conducted. The goal is to demonstrate the need and feasibility of using ADR to better preserve the future environment and to guide its implementation to maximize the benefit-to-cost ratio. This paper describes a new sensitivity study on using ADR to stabilize the future LEO debris environment. The NASA long-term orbital debris evolutionary model, LEGEND, is used to quantify the effects of several key parameters, including target selection criteria/constraints and the starting epoch of ADR implementation. Additional analyses on potential ADR targets among the currently existing satellites and the benefits of collision avoidance maneuvers are also included.

Atividade antifúngica de óleos essenciais sobre espécies de Candida

Directory of Open Access Journals (Sweden)

Igara de Oliveira Lima

Full Text Available A candidíase apresenta-se como uma infecção fúngica superficial ou profunda causada por leveduras pertencentes ao gênero Candida, sendo considerada a principal infecção micótica em ambiente nosocomial. O objetivo do presente estudo foi determinar a concentração inibitória mínima - CIM do óleo essencial de Cinnamomum zeylanicum Blume, Citrus limon Risso, Eucalyptus citriodora HK, Eugenia uniflora L., Peumus boldus Benth e de Rosmarinus officinialis L. sobre cepas de Candida albicans, C. guilliermondii, C. krusei, C. parapsilosis, C. stellatoidea e C. tropicalis. Os ensaios de atividade antifúngica foram realizados através da técnica de difusão em meio sólido. Os óleos essenciais de C. zeylanicum e P. boldus mostraram os mais destacáveis resultados, visto que inibiram o crescimento de 58% das cepas ensaiadas e apresentaram CIM de 4%.

The Komplast Experiment: Space Environmental Effects after 12 Years in LEO (and Counting)

Science.gov (United States)

Golden, J. L.; Shaevich, S.; Aleksandrov, N. G.; Shumov, A. E.; Novikov, L. S.; Alred, J. A.; Shindo, D. J.; Kravchenko, M.

2014-01-01

The Komplast materials experiment was designed by the Khrunichev Space Center, together with other Russian scientific institutes, and has been carried out by Mission Control Moscow since 1998. The purpose is to study the effect of the low earth orbit (LEO) environment on exposed samples of various spacecraft materials. The Komplast experiment began with the launch of the first International Space Station (ISS) module on November 20, 1998. Two of eight experiment panels were retrieved during Russian extravehicular activity in February 2011 after 12 years of LEO exposure, and were subsequently returned to Earth by Space Shuttle "Discovery" on the STS-133/ULF-5 mission. The retrieved panels contained an experiment to detect micrometeoroid and orbital debris (MMOD) impacts, radiation sensors, a temperature sensor, several pieces of electrical cable, both carbon composite and adhesive-bonded samples, and many samples made from elastomeric and fluoroplastic materials. Our investigation is complete and a summary of the results obtained from this uniquely long-duration exposure experiment will be presented.

PREVALENCE OF SMALL INTESTINAL BACTERIAL OVERGROWTH IN IRRITABLE BOWEL SYNDROME

Directory of Open Access Journals (Sweden)

Premaletha Narayanan

2017-12-01

Full Text Available BACKGROUND Irritable Bowel Syndrome (IBS is a common functional disorder and the pathophysiology of IBS is poorly understood. The aim of the study is to assess the prevalence of SIBO in patients with IBS using Lactulose Hydrogen Breath Test (LHBT. Diagnosis of IBS was made according to the Rome III Criteria and Lactulose Hydrogen Breath Test (LHBT was done. MATERIALS AND METHODS The current hypothesis suggests that altered gastrointestinal motility, disturbance of visceral hypersensitivity and infection may contribute to the symptoms. Gut microbiota and intestinal pathogens are likely to influence the pathogenesis of IBS. Small Intestinal Bacterial Overgrowth (SIBO is defined as an abnormally high bacterial count (≥105 colony-forming units/mL in the proximal small intestine. RESULTS Out of the 120 patients, 9 were LHBT positive (7.5% compared to none in controls (p <0.01. IBS patients with LHBT positivity was correlated well with the increased frequency of stools. There was no correlation noted with LHBT positivity and abdominal pain or flatulence or bloating compared to IBS patients who were LHBT negative. CONCLUSION These findings may suggest that patients with chronic diarrhoea including IBS should be tested for SIBO. Our study also showed that LHBT positivity is associated with increased frequency of stools and diarrhoea. If SIBO is found in patients with chronic diarrhoea, specific treatment with antibiotics may benefit them.

Potential of eleven Eucalyptus species for the production of essential oils Potencial de onze espécies de eucalipto para a produção de óleos essenciais

Directory of Open Access Journals (Sweden)

Paulo Henrique Müller da Silva

2006-02-01

Full Text Available Most Eucalyptus plantations in Brazil aim the production of paper and charcoal, but the use of the species for lumbering, construction and extraction of essential oil has increased. Eleven species of Eucalyptus were assessed in regard to their essential oil production potential, nine never used before for commercial, essential oil extraction. Assessements were compared with Eucalyptus citriodora and Eucalyptus globulus, already explored in oil production for perfume and medical purposes, aiming to increase the availability of commercial species and the relationship between oil production and climatic conditions. Eucalyptus leaves were seasonally sampled (three months interval for distillation and determination of productivity and chemical composition of oil - contents of oils main components. Eucalyptus viminalis showed the highest potential for cineol, and standed out among the species not yet used commercially. Influenced by soil moisture contents and air temperature, the lowest and the highest oil production happened respectively in Spring and Summer. Water deficiency in Spring caused the lowest oil production. In the Summer, on the other hand, the highest oil production was observed when temperatures were higher and no water deficiency registered. There was no climatic influence on the main oil chemical component.A maioria das plantações de Eucalyptus brasileiras tem como objetivo a produção de papel e carvão, mas o uso das espécies para madeira, construção e extração de óleo essencial tem aumentado. Neste trabalho foram estudadas onze espécies de eucalipto quanto ao potencial para a obtenção de óleo essencial. Entre as espécies estudadas, nove não têm sido utilizadas na obtenção comercial de óleo. Para efeito comparativo, avaliou-se também duas outras espécies, o Eucalyptus citriodora e o Eucalyptus globulus, as quais são amplamente utilizadas, respectivamente, para a obtenção de óleo aromatizante e óleo para

Photovoltaic x-ray detectors based on the GaAs epitaxial structures

CERN Document Server

Akhmadullin, R A; Dvoryankina, G G; Dikaev, Y M; Ermakov, M G; Ermakova, O N; Krikunov, A I; Kudryashov, A A; Petrov, A G; Telegin, A A

2002-01-01

The new photovoltaic detector of the X-ray radiation is proposed on the basis of the GaAs epitaxial structures, which operates with high efficiency of the charge carriers collection without shift voltage and at the room temperature. The structures are grown by the method of the gas-phase epitaxy on the n sup + -type highly-alloyed substrates. The range of sensitivity to the X-ray radiation is within the range of effective energies from 8 up to 120 keV. The detector maximum response in the current short circuit mode is determined

Epitaxial heterojunctions of oxide semiconductors and metals on high temperature superconductors

Science.gov (United States)

Vasquez, Richard P. (Inventor); Hunt, Brian D. (Inventor); Foote, Marc C. (Inventor)

1994-01-01

Epitaxial heterojunctions formed between high temperature superconductors and metallic or semiconducting oxide barrier layers are provided. Metallic perovskites such as LaTiO3, CaVO3, and SrVO3 are grown on electron-type high temperature superconductors such as Nd(1.85)Ce(0.15)CuO(4-x). Alternatively, transition metal bronzes of the form A(x)MO(3) are epitaxially grown on electron-type high temperature superconductors. Also, semiconducting oxides of perovskite-related crystal structures such as WO3 are grown on either hole-type or electron-type high temperature superconductors.

Design and Fabrication of DebriSat - A Representative LEO Satellite for Improvements to Standard Satellite Breakup Models

Science.gov (United States)

Clark, S.; Dietrich, A.; Fitz-Coy, N.; Weremeyer, M.; Liou, J.-C.

2012-01-01

This paper discusses the design and fabrication of DebriSat, a 50 kg satellite developed to be representative of a modern low Earth orbit satellite in terms of its components, materials used, and fabrication procedures. DebriSat will be the target of a future hypervelocity impact experiment to determine the physical characteristics of debris generated after an on-orbit collision of a modern LEO satellite. The major ground-based satellite impact experiment used by DoD and NASA in their development of satellite breakup models was SOCIT, conducted in 1992. The target used for that experiment was a Navy transit satellite (40 cm, 35 kg) fabricated in the 1960's. Modern satellites are very different in materials and construction techniques than those built 40 years ago. Therefore, there is a need to conduct a similar experiment using a modern target satellite to improve the fidelity of the satellite breakup models. To ensure that DebriSat is truly representative of typical LEO missions, a comprehensive study of historical LEO satellite designs and missions within the past 15 years for satellites ranging from 1 kg to 5000 kg was conducted. This study identified modern trends in hardware, material, and construction practices utilized in recent LEO missions. Although DebriSat is an engineering model, specific attention is placed on the quality, type, and quantity of the materials used in its fabrication to ensure the integrity of the outcome. With the exception of software, all other aspects of the satellite s design, fabrication, and assembly integration and testing will be as rigorous as that of an actual flight vehicle. For example, to simulate survivability of launch loads, DebriSat will be subjected to a vibration test. As well, the satellite will undergo thermal vacuum tests to verify that the components and overall systems meet typical environmental standards. Proper assembly and integration techniques will involve comprehensive joint analysis, including the precise

Reducing classification error of grassland overgrowth by combing low-density lidar acquisitions and optical remote sensing data

Science.gov (United States)

Pitkänen, T. P.; Käyhkö, N.

2017-08-01

Mapping structural changes in vegetation dynamics has, for a long time, been carried out using satellite images, orthophotos and, more recently, airborne lidar acquisitions. Lidar has established its position as providing accurate material for structure-based analyses but its limited availability, relatively short history, and lack of spectral information, however, are generally impeding the use of lidar data for change detection purposes. A potential solution in respect of detecting both contemporary vegetation structures and their previous trajectories is to combine lidar acquisitions with optical remote sensing data, which can substantially extend the coverage, span and spectral range needed for vegetation mapping. In this study, we tested the simultaneous use of a single low-density lidar data set, a series of Landsat satellite frames and two high-resolution orthophotos to detect vegetation succession related to grassland overgrowth, i.e. encroachment of woody plants into semi-natural grasslands. We built several alternative Random Forest models with different sets of variables and tested the applicability of respective data sources for change detection purposes, aiming at distinguishing unchanged grassland and woodland areas from overgrown grasslands. Our results show that while lidar alone provides a solid basis for indicating structural differences between grassland and woodland vegetation, and orthophoto-generated variables alone are better in detecting successional changes, their combination works considerably better than its respective parts. More specifically, a model combining all the used data sets reduces the total error from 17.0% to 11.0% and omission error of detecting overgrown grasslands from 56.9% to 31.2%, when compared to model constructed solely based on lidar data. This pinpoints the efficiency of the approach where lidar-generated structural metrics are combined with optical and multitemporal observations, providing a workable framework to

Structural evolution of epitaxial SrCoOx films near topotactic phase transition

OpenAIRE

Hyoungjeen Jeen; Ho Nyung Lee

2015-01-01

Control of oxygen stoichiometry in complex oxides via topotactic phase transition is an interesting avenue to not only modifying the physical properties, but utilizing in many energy technologies, such as energy storage and catalysts. However, detailed structural evolution in the close proximity of the topotactic phase transition in multivalent oxides has not been much studied. In this work, we used strontium cobaltites (SrCoOx) epitaxially grown by pulsed laser epitaxy (PLE) as a model syste...

Phylogeographic Patterns in Africa and High Resolution Delineation of Genetic Clades in the Lion (Panthera leo)

Science.gov (United States)

Bertola, L. D.; Jongbloed, H.; van der Gaag, K. J.; de Knijff, P.; Yamaguchi, N.; Hooghiemstra, H.; Bauer, H.; Henschel, P.; White, P. A.; Driscoll, C. A.; Tende, T.; Ottosson, U.; Saidu, Y.; Vrieling, K.; de Iongh, H. H.

2016-08-01

Comparative phylogeography of African savannah mammals shows a congruent pattern in which populations in West/Central Africa are distinct from populations in East/Southern Africa. However, for the lion, all African populations are currently classified as a single subspecies (Panthera leo leo), while the only remaining population in Asia is considered to be distinct (Panthera leo persica). This distinction is disputed both by morphological and genetic data. In this study we introduce the lion as a model for African phylogeography. Analyses of mtDNA sequences reveal six supported clades and a strongly supported ancestral dichotomy with northern populations (West Africa, Central Africa, North Africa/Asia) on one branch, and southern populations (North East Africa, East/Southern Africa and South West Africa) on the other. We review taxonomies and phylogenies of other large savannah mammals, illustrating that similar clades are found in other species. The described phylogeographic pattern is considered in relation to large scale environmental changes in Africa over the past 300,000 years, attributable to climate. Refugial areas, predicted by climate envelope models, further confirm the observed pattern. We support the revision of current lion taxonomy, as recognition of a northern and a southern subspecies is more parsimonious with the evolutionary history of the lion.

Phylogeographic Patterns in Africa and High Resolution Delineation of Genetic Clades in the Lion (Panthera leo).

Science.gov (United States)

Bertola, L D; Jongbloed, H; van der Gaag, K J; de Knijff, P; Yamaguchi, N; Hooghiemstra, H; Bauer, H; Henschel, P; White, P A; Driscoll, C A; Tende, T; Ottosson, U; Saidu, Y; Vrieling, K; de Iongh, H H

2016-08-04

Comparative phylogeography of African savannah mammals shows a congruent pattern in which populations in West/Central Africa are distinct from populations in East/Southern Africa. However, for the lion, all African populations are currently classified as a single subspecies (Panthera leo leo), while the only remaining population in Asia is considered to be distinct (Panthera leo persica). This distinction is disputed both by morphological and genetic data. In this study we introduce the lion as a model for African phylogeography. Analyses of mtDNA sequences reveal six supported clades and a strongly supported ancestral dichotomy with northern populations (West Africa, Central Africa, North Africa/Asia) on one branch, and southern populations (North East Africa, East/Southern Africa and South West Africa) on the other. We review taxonomies and phylogenies of other large savannah mammals, illustrating that similar clades are found in other species. The described phylogeographic pattern is considered in relation to large scale environmental changes in Africa over the past 300,000 years, attributable to climate. Refugial areas, predicted by climate envelope models, further confirm the observed pattern. We support the revision of current lion taxonomy, as recognition of a northern and a southern subspecies is more parsimonious with the evolutionary history of the lion.

Liquid phase electro epitaxy growth kinetics of GaAs-A three-dimensional numerical simulation study

International Nuclear Information System (INIS)

Mouleeswaran, D.; Dhanasekaran, R.

2006-01-01

A three-dimensional numerical simulation study for the liquid phase electro epitaxial growth kinetic of GaAs is presented. The kinetic model is constructed considering (i) the diffusive and convective mass transport, (ii) the heat transfer due to thermoelectric effects such as Peltier effect, Joule effect and Thomson effect, (iii) the electric current distribution with electromigration and (iv) the fluid flow coupled with concentration and temperature fields. The simulations are performed for two configurations namely (i) epitaxial growth from the arsenic saturated gallium rich growth solution, i.e., limited solution model and (ii) epitaxial growth from the arsenic saturated gallium rich growth solution with polycrystalline GaAs feed. The governing equations of liquid phase electro epitaxy are solved numerically with appropriate initial and boundary conditions using the central difference method. Simulations are performed to determine the following, a concentration profiles of solute atoms (As) in the Ga-rich growth solution, shape of the substrate evolution, the growth rate of the GaAs epitaxial film, the contributions of Peltier effect and electromigration of solute atoms to the growth with various experimental growth conditions. The growth rate is found to increase with increasing growth temperature and applied current density. The results are discussed in detail

Improvement of Metal-Graphene Ohmic Contact Resistance in Bilayer Epitaxial Graphene Devices

International Nuclear Information System (INIS)

He Ze-Zhao; Yang Ke-Wu; Yu Cui; Li Jia; Liu Qing-Bin; Lu Wei-Li; Feng Zhi-Hong; Cai Shu-Jun

2015-01-01

We report on an improved metal-graphene ohmic contact in bilayer epitaxial graphene on a SiC substrate with contact resistance below 0.1 ω·mm. Monolayer and bilayer epitaxial graphenes are prepared on a 4H-SiC substrate in this work. Their contact resistances are measured by a transfer length method. An improved photoresist-free device fabrication method is used and is compared with the conventional device fabrication method. Compared with the monolayer graphene, the contact resistance R c of bilayer graphene improves from an average of 0.24 ω·mm to 0.1 ω·mm. Ohmic contact formation mechanism analysis by Landauer's approach reveals that the obtained low ohmic contact resistance in bilayer epitaxial graphene is due to their high carrier density, high carrier transmission probability, and p-type doping introduced by contact metal Au. (paper)

Optical and electro-optic anisotropy of epitaxial PZT thin films

Science.gov (United States)

Zhu, Minmin; Du, Zehui; Jing, Lin; Yoong Tok, Alfred Iing; Tong Teo, Edwin Hang

2015-07-01

Strong optical and electro-optic (EO) anisotropy has been investigated in ferroelectric Pb(Zr0.48Ti0.52)O3 thin films epitaxially grown on Nb-SrTiO3 (001), (011), and (111) substrates using magnetron sputtering. The refractive index, electro-optic, and ferroelectric properties of the samples demonstrate the significant dependence on the growth orientation. The linear electro-optic coefficients of the (001), (011), and (111)-oriented PZT thin films were 270.8, 198.8, and 125.7 pm/V, respectively. Such remarkable anisotropic EO behaviors have been explained according to the structure correlation between the orientation dependent distribution, spontaneous polarization, epitaxial strain, and domain pattern.

Superconductivity of Rock-Salt Structure LaO Epitaxial Thin Film.

Science.gov (United States)

Kaminaga, Kenichi; Oka, Daichi; Hasegawa, Tetsuya; Fukumura, Tomoteru

2018-06-06

We report a superconducting transition in a LaO epitaxial thin film with the superconducting transition onset temperature ( T c ) at around 5 K. This T c is higher than those of other lanthanum monochalcogenides and opposite to their chemical trend: T c = 0.84, 1.02, and 1.48 K for LaX (X = S, Se, Te), respectively. The carrier control resulted in a dome-shaped T c as a function of electron carrier density. In addition, the T c was significantly sensitive to epitaxial strain in spite of the highly symmetric crystal structure. This rock-salt superconducting LaO could be a building block to design novel superlattice superconductors.

ANÁLISE DE SUPERFÍCIE DE RESPOSTA DOS BLENDS DO ÓLEO DE MAMONA E BABAÇU

Directory of Open Access Journals (Sweden)

Francisco Francielle Pinheiro dos Santos

2014-09-01

Full Text Available A mamona, (Ricinus communis L., é uma planta oleaginosa que tem recebido grande destaque no programa brasileiro de biodiesel. O Programa fez a opção pelo plantio da mamona devido as suas características de cultivo, adaptação a múltiplos tipos de solo e características da gestão familiar. No entanto, devido a sua elevada viscosidade, o óleo de mamona tem sido cada vez mais descartado do cenário brasileiro da produção de biodiesel, sendo assim, torna-se necessário a mistura (blends deste óleo com outros de menor viscosidade. Diante deste contexto, temos como objetivo determinar através de análise de superfície de resposta, a faixa de blends entre os óleos de mamona e babaçu que possuam viscosidades aceitáveis de acordo com as normas vigentes. Este trabalho também analisará aspectos reacionais uma vez que leva em consideração a variação da razão molar na reação.

Los derrames de petróleo : Su impacto ambiental

OpenAIRE

Zlatar, Yerko

1994-01-01

Los yacimientos de hidrocarburos se localizan, en su mayoría, en lugares alejados de los centros de consumo o de las industrias de procesamiento (destilerías), por tanto el petróleo y sus derivados se transportan mediante embarcaciones de gran tonelaje. Casi el 50% de la flota mundial, que navega a través de las vías marítimas y fluviales, está compuesta por barcos cisternas (tanqueros) que trasladan miles de millones de metros cúbicos de hidrocarburos. Durante las operaciones de carga y desc...

The Tectonics of Love in Leo Tolstoy’s Resurrection

Directory of Open Access Journals (Sweden)

Głąb Anna

2016-09-01

Full Text Available The text analyzes Leo Tolstoy’s Resurrection focusing on the feelings expressed in the novel. It focuses on: (I the ways in which the content of the novel is expressed through artistic means; (II Tolstoy’s anthropology; (III the notion of love presented by Ronald de Sousa in his last book Love. A Very Short Introduction: the difference between love and mood or emotion; the classification of love (philia, storge, agape, eros; the distinction between love and lust; love as a reason-free desire; and the notion of the historicity of love.

Study on structural properties of epitaxial silicon films on annealed double layer porous silicon

International Nuclear Information System (INIS)

Yue Zhihao; Shen Honglie; Cai Hong; Lv Hongjie; Liu Bin

2012-01-01

In this paper, epitaxial silicon films were grown on annealed double layer porous silicon by LPCVD. The evolvement of the double layer porous silicon before and after thermal annealing was investigated by scanning electron microscope. X-ray diffraction and Raman spectroscopy were used to investigate the structural properties of the epitaxial silicon thin films grown at different temperature and different pressure. The results show that the surface of the low-porosity layer becomes smooth and there are just few silicon-bridges connecting the porous layer and the substrate wafer. The qualities of the epitaxial silicon thin films become better along with increasing deposition temperature. All of the Raman peaks of silicon films with different deposition pressure are situated at 521 cm -1 under the deposition temperature of 1100 °C, and the Raman intensity of the silicon film deposited at 100 Pa is much closer to that of the monocrystalline silicon wafer. The epitaxial silicon films are all (4 0 0)-oriented and (4 0 0) peak of silicon film deposited at 100 Pa is more symmetric.

Boron, arsenic and phosphorus dopant incorporation during low temperature low pressure silicon epitaxial growth

International Nuclear Information System (INIS)

Borland, J.O.; Thompson, T.; Tagle, V.; Benzing, W.

1987-01-01

Submicron silicon epitaxial structures with very abrupt epi/substrate transition widths have been realized through the use of low temperature silicon epitaxial growth techniques. At these low temperature and low pressure epitaxial growth conditions there is minimal, if any, dopant diffusion from the substrate into the epilayer during deposition. The reincorporation of autodoped dopant as well as the incorporation of intentional dopant can be a trade-off at low temperatures and low pressures. For advanced CMOS and Bi-CMOS technologies, five to six orders of magnitude change in concentration levels are desirable. In this investigation, all of the epitaxial depositions were carried out in an AMC-7810 epi-reactor with standard jets for a turbulent mixing system, and using a modified center inject configuration to achieve a single pass laminar flow system. To simulate the reincorporation of various autodoped dopant, the authors ran a controlled dopant flow of 100 sccm for each of the three dopants (boron, phosphorus and arsenic) to achieve the controlled background dopant level in the reactor gas stream

Personality assessment and feline–keepers relationship in lions (Panthera leo)

OpenAIRE

Quintavalle Pastorino, Giovanni; Soares, Nuno; Mazzola, Silvia Michela; Preziosi, Richard; Albertini, Mariangela

2016-01-01

Animal personality is a growing research area due to the increasing evidence of the impact that it has on welfare, health and management of animals in captivity (Freeman and Gosling, 2010). Testing and improving existent methodologies, as well as develop new ones, to outline animal personality is an important step towards welfare, health and longevity of captive animals (Phillips, 2007; Whitham and Wielebnowski, 2013). Lions (Panthera leo) were chosen for this study because the species is und...

PRIMA Platform capability for satellite missions in LEO and MEO (SAR, Optical, GNSS, TLC, etc.)

Science.gov (United States)

Logue, T.; L'Abbate, M.

2016-12-01

PRIMA (Piattaforma Riconfigurabile Italiana Multi Applicativa) is a multi-mission 3-axis stabilized Platform developed by Thales Alenia Space Italia under ASI contract.PRIMA is designed to operate for a wide variety of applications from LEO, MEO up to GEO and for different classes of satellites Platform Family. It has an extensive heritage in flight heritage (LEO and MEO Satellites already fully operational) in which it has successfully demonstrated the flexibility of use, low management costs and the ability to adapt to changing operational conditions.The flexibility and modularity of PRIMA provides unique capability to satisfy different Payload design and mission requirements, thanks to the utilization of recurrent adaptable modules (Service Module-SVM, Propulsion Module-PPM, Payload Module-PLM) to obtain mission dependent configuration. PRIMA product line development is continuously progressing, and is based on state of art technology, modular architecture and an Integrated Avionics. The aim is to maintain and extent multi-mission capabilities to operate in different environments (LEO to GEO) with different payloads (SAR, Optical, GNSS, TLC, etc.). The design is compatible with a wide range of European and US equipment suppliers, thus maximising cooperation opportunity. Evolution activities are mainly focused on the following areas: Structure: to enable Spacecraft configurations for multiple launch; Thermal Control: to guarantee thermal limits for new missions, more demanding in terms of environment and payload; Electrical: to cope with higher power demand (e.g. electrical propulsion, wide range of payloads, etc.) considering orbital environment (e.g. lighting condition); Avionics : AOCS solutions optimized on mission (LEO observation driven by agility and pointing, agility not a driver for GEO). Use of sensors and actuators tailored for specific mission and related environments. Optimised Propulsion control. Data Handling, SW and FDIR mission customization

Aproveitamento dos subprodutos da extra??o do ?leo do pau-rosa (Aniba rosaeodora Ducke) para a obten??o de bioprodutos

OpenAIRE

Cust?dio, Dayana Lacerda

2013-01-01

A fam?lia Lauraceae destaca-se por apresentar esp?cies com grande import?ncia econ?mica, dentre elas Aniba rosaeodora Ducke, utilizada na extra??o de ?leo essencial. Seu ?leo essencial ? formado majoritariamente por linalol, utilizado como fixador na perfumaria. Os subprodutos da extra??o do pau-rosa s?o geralmente empregados como fonte de energia para o aquecimento das caldeiras nas pr?prias usinas. Estes subprodutos cont?m subst?ncias com grande potencial de aproveitamento como biopro...

Epitaxial Al2O3 capacitors for low microwave loss superconducting quantum circuits

Directory of Open Access Journals (Sweden)

K.-H. Cho

2013-10-01

Full Text Available We have characterized the microwave loss of high-Q parallel plate capacitors fabricated from thin-film Al/Al2O3/Re heterostructures on (0001 Al2O3 substrates. The superconductor-insulator-superconductor trilayers were grown in situ in a hybrid deposition system: the epitaxial Re base and polycrystalline Al counterelectrode layers were grown by sputtering, while the epitaxial Al2O3 layer was grown by pulsed laser deposition. Structural analysis indicates a highly crystalline epitaxial Al2O3 layer and sharp interfaces. The measured intrinsic (low-power, low-temperature quality factor of the resonators is as high as 3 × 104. These results indicate that low-loss grown Al2O3 is an attractive candidate dielectric for high-fidelity superconducting qubit circuits.

Epitaxial strain-engineered self-assembly of magnetic nanostructures in FeRh thin films

International Nuclear Information System (INIS)

Witte, Ralf; Kruk, Robert; Molinari, Alan; Wang, Di; Brand, Richard A; Hahn, Horst; Schlabach, Sabine; Provenzano, Virgil

2017-01-01

In this paper we introduce an innovative bottom–up approach for engineering self-assembled magnetic nanostructures using epitaxial strain-induced twinning and phase separation. X-ray diffraction, 57 Fe Mössbauer spectroscopy, scanning tunneling microscopy, and transmission electron microscopy show that epitaxial films of a near-equiatomic FeRh alloy respond to the applied epitaxial strain by laterally splitting into two structural phases on the nanometer length scale. Most importantly, these two structural phases differ with respect to their magnetic properties, one being paramagnetic and the other ferromagnetic, thus leading to the formation of a patterned magnetic nanostructure. It is argued that the phase separation directly results from the different strain-dependence of the total energy of the two competing phases. This straightforward relation directly enables further tailoring and optimization of the nanostructures’ properties. (paper)

Avaliação da atividade fungicida de extratos e óleos essenciais sobre ferrugem asiática da soja

Directory of Open Access Journals (Sweden)

Daísa Bigaton

Full Text Available Os extratos e óleos essenciais extraídos de plantas têm grande potencial no controle de fitopatógenos, por sua ação fungitóxica direta, inibindo o crescimento micelial e a germinação de esporos, e pela capacidade de induzir o acúmulo de fitoalexinas nas plantas. Objetivou-se com esse trabalho avaliar o efeito de diferentes extratos metanólicos e óleos essenciais sobre a ferrugem asiática da soja (Phakopsora pachyrhizi. O experimento foi realizado em casa-de-vegetação e sala de incubação. Utilizou-se o delineamento inteiramente casualizado com sete tratamentos e dez repetições. A cultivar de soja utilizada foi a BRS 245RR; os tratamentos constaram de óleos essenciais e extratos metanólicos dos gêneros Schinus terebinthifolius (aroeira-pimenteira, e Trichilia silvatica (quebra-machado, catiguá-vermelho, surfactante Tween 80 a 1% (v/v e a testemunha água. As plantas foram pulverizadas com os respectivos tratamentos e inoculadas artificialmente com o fungo cerca de 24 horas depois. As características analisadas foram: número de folíolos/parcela; índice de clorofila; altura de plantas; intensidade da ferrugem asiática da soja; número de folíolos com ferrugem; número de folíolos com aspecto queimado. As plantas pulverizadas com extrato de Schinus a 5% (m/v e óleo de Schinus a 1% (v/v mostraram maior intensidade da doença, comparadas às pulverizadas com água. Estes dois tratamentos e o óleo de Trichilia a 1% provocaram uma maior incidência de folíolos queimados, indicando fitotoxicidade à cultura.

Changes in the composition, structure and friction property of sputtered MoS2 films by LEO environment exposure

International Nuclear Information System (INIS)

Gao, Xiaoming; Hu, Ming; Sun, Jiayi; Fu, Yanlong; Yang, Jun; Liu, Weimin; Weng, Lijun

2015-01-01

Highlights: • Sputtered MoS 2 films were exposed in real low earth orbit (LEO) environment. • LEO exposure resulted in the oxidation and S loss of MoS 2 film surface. • Depth affected by the LEO exposure was limited within 10 nm. • The exposed MoS 2 film exhibited a slight increase in friction coefficient at initial sliding stage. - Abstract: Radio frequency-sputtered MoS 2 films had been exposed for 43.5 h in real low earth orbit (LEO) space environment by a space environment exposure device (SEED) aboard China Shenzhou-7 manned spaceship. The composition, morphology, phase structure and friction property of the exposed films were investigated using X-ray photoelectron spectroscope (XPS), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), X-ray energy-dispersive spectroscopy (EDS) and ball-on-disk tribometer. XRD and EDS results revealed that the as-deposited MoS 2 films were characterized by a MoS x O y phase structure, in which x and y values were determined to be ∼0.65 and 1.24, respectively. XPS analysis revealed that due to space atomic oxygen attack, the film surface was oxidized to MoO 3 and MoS x O y with higher O concentration, while the partial S was lost. However, the affected depth was restricted within the surface layer because of protective function of the oxidation layer. As a result, the friction coefficient only exhibited a slight increase at initial stage of sliding friction

A critical discussion of the vacancy diffusion model of ion beam induced epitaxial crystallization

International Nuclear Information System (INIS)

Heera, V.

1989-01-01

A simple vacancy diffusion model of ion beam induced epitaxial crystallization of silicon including divacancy formation is developed. The model reproduces some of the experimental findings, as e.g. the dose rate dependence of the crystallization rate. However, the measured activation energy of the ion beam induced epitaxial crystallization cannot be accounted for by vacancy diffusion alone. (author)

Structural and magentic characterization of rare earth and transition metal films grown on epitaxial buffer films on semiconductor substrates

International Nuclear Information System (INIS)

Farrow, R.F.C.; Parkin, S.S.P.; Speriosu, V.S.; Bezinge, A.; Segmuller, A.P.

1989-01-01

Structural and magnetic data are presented and discussed for epitaxial films of rare earth metals (Dy, Ho, Er) on LaF 3 films on the GaAs(TTT) surface and Fe on Ag films on the GaAs(001) surface. Both systems exhibit unusual structural characteristics which influence the magnetic properties of the metal films. In the case of rare earth epitaxy on LaF 3 the authors present evidence for epitaxy across an incommensurate or discommensurate interface. Coherency strain is not transmitted into the metal which behaves much like bulk crystals of the rare earths. In the case of Fe films, tilted epitaxy and long-range coherency strain are confirmed by X- ray diffractometry. Methods of controlling some of these structural effects by modifying the epitaxial structures are presented

A problemática do petróleo

OpenAIRE

Nunes, João Belchior

2013-01-01

Tudo que se digaou se escreva sobre o preço do barril de petróleo no mercado, não provará que este resulta da lei da oferta e da procura. este facto é considerado na medida em que a oferta é, de alguma forma controlada pelos países produtores que, por enquanto, excepção feita para algumas traições, não deixam que exista um excesso de oferta. isto não obsta que não se possa dizer que existe um oligopólio da oferta, a organização dos Países exportador...

A new approach to epitaxially grow high-quality GaN films on Si substrates: the combination of MBE and PLD.

Science.gov (United States)

Wang, Wenliang; Wang, Haiyan; Yang, Weijia; Zhu, Yunnong; Li, Guoqiang

2016-04-22

High-quality GaN epitaxial films have been grown on Si substrates with Al buffer layer by the combination of molecular beam epitaxy (MBE) and pulsed laser deposition (PLD) technologies. MBE is used to grow Al buffer layer at first, and then PLD is deployed to grow GaN epitaxial films on the Al buffer layer. The surface morphology, crystalline quality, and interfacial property of as-grown GaN epitaxial films on Si substrates are studied systematically. The as-grown ~300 nm-thick GaN epitaxial films grown at 850 °C with ~30 nm-thick Al buffer layer on Si substrates show high crystalline quality with the full-width at half-maximum (FWHM) for GaN(0002) and GaN(102) X-ray rocking curves of 0.45° and 0.61°, respectively; very flat GaN surface with the root-mean-square surface roughness of 2.5 nm; as well as the sharp and abrupt GaN/AlGaN/Al/Si hetero-interfaces. Furthermore, the corresponding growth mechanism of GaN epitaxial films grown on Si substrates with Al buffer layer by the combination of MBE and PLD is hence studied in depth. This work provides a novel and simple approach for the epitaxial growth of high-quality GaN epitaxial films on Si substrates.

Investigação da presença de óleo essencial em Eucalyptus smithii R.T. Baker por meio da anatomia de seu lenho e casca.

Directory of Open Access Journals (Sweden)

Fernando José Fabrowski

2010-08-01

Full Text Available O material utilizado no presente estudo foi proveniente de 15 árvores de Eucalyptus smithii R.T. Baker cultivadas no município de Colombo - PR, em campo experimental da Embrapa Florestas, plantadas em 1988. Caracterizou-se anatomicamente o lenho e a casca por meio de lâminas preparadas no Laboratório de Anatomia e Identificação de Madeiras do IPT e Laboratório de Anatomia da Madeira, do Centro de Ciências Florestais e da Madeira, da Universidade Federal do Paraná. Para a extração do óleo essencial, a madeira foi transformada em serragem e a casca desfibrada manualmente. Para a determinação do rendimento e análise do óleo essencial, foram efetuadas destilações conforme ABNT no Laboratório de Fitoquímica do Departamento de Farmácia da Universidade Federal do Paraná. Os rendimentos do óleo essencial foram dados em volume (ml de óleo essencial por massa (g de material. O Eucalyptus smithii apresenta estrutura anatômica homogênea do lenho e da casca. Na casca, observou-se a presença de cavidades secretoras; no entanto, no lenho, não foi encontrada nenhuma estrutura semelhante, apenas bolsas de quino, sendo desprezível a quantidade de óleo essencial presente na madeira. O óleo essencial da casca apresentou características físico-químicas fora das especificações para óleos essenciais de eucaliptos ricos em 1,8-cineol, não sendo economicamente viável para a exploração desse componente.

Caracterización preliminar de la jalea de propóleos al 10 % para uso estomatológico

OpenAIRE

Padró-Rodríguez, Lourdes; Chil-Núñez, Idelsys

2014-01-01

El propóleos constituye la base de muchas formulaciones farmacéuticas. El presente trabajo propone la caracterización preliminar de una jalea de propóleos para el tratamiento de la gingivitis. Se realizó un estudio en el Laboratorio de Tecnología Farmacéutica de la Universidad de Oriente en el periodo marzo-mayo 2013; por medio del empleo del método de incorporación se procedió a la elaboración de la jalea, a la cual se le evaluaron los parámetros de calidad establecidos. Los mismos mostraron...

Avaliação das Propriedades de Óleos Vegetais Visando a Produção de Biodiesel

OpenAIRE

Melo, Maria Andrea Mendes Formiga

2014-01-01

A maior conscientização dos países na busca por combustíveis alternativos que minimizem a emissão de poluentes tem contribuído para que sejam desenvolvidos combustíveis a partir de biomassas renováveis. Dentre estas, os óleos vegetais aparecem como uma excelente alternativa para substituição do diesel mineral, uma vez que o processo de transesterificação resulta na produção do biodiesel. O presente estudo teve por objetivos estabelecer a composição em metilésteres dos óleos ...

EPOXIDAÇÃO DE ÓLEOS DE SOJA, GIRASSOL E MAMONA E AVALIAÇÃO QUIMIOMÉTRICA POR PCA e HCA

Directory of Open Access Journals (Sweden)

Fernanda Carla Bock

2014-11-01

Full Text Available Este estudo teve por objetivo realizar a epoxidação de diferentes óleos vegetais (girassol, mamona e soja e realizar a identificação assim como o acompanhamento reacional através da espectroscopia no infravermelho médio aplicando métodos multivariados de análise (análise de componentes principais – PCA e análise de agrupamento hierárquico – HCA. Os resultados obtidos mostraram que é possível obter epóxidos a partir de ésteres dos óleos de mamona, soja e girassol e que a taxa de conversão está associada ao tempo, a quantidade de enzima e ao óleo vegetal empregado. O estudo também indica que é possível o acompanhamento reacional através da espectroscopia no infravermelho médio associado à análise de componentes principais (PCA e a identificação dos epóxidos obtidos a partir de óleos de girassol, mamona e soja através da espectroscopia no infravermelho médio associada à análise de componentes principais (PCA e análise por agrupamento hierárquico (HCA.

X-ray diffraction study of rare earth epitaxial structures grown by MBE onto (111) GaAs

International Nuclear Information System (INIS)

Bennett, W.R.; Farrow, R.F.C.; Parkin, S.S.P.; Marinero, E.E.; Segmuller, A.P.

1989-01-01

The authors report on the new epitaxial system LaF 3 /Er/Dy/Er/LaF 3 /GaAs(111) grown by molecular beam epitaxy. X-ray diffraction studies have been used to determine the epitaxial relationships between the rare earths, the LaF 3 and the substrate. Further studies of symmetric and asymmetric reflections yielded the in-plane and perpendicular strain components of the rare earth layers. Such systems may be used to probe the effects of magnetoelastic interactions and dimensionality on magnetic ordering in rare earth metal films

Avaliação da qualidade do óleo de palma e frações (Elaeis guineenses) armazenados em diferentes condições de estocagem

OpenAIRE

Matos, Vanessa de Souza

2015-01-01

O óleo de palma bruto (OPB) ou azeite de dendê (Elaeis guineenses) apresenta composição equilibrada em ácidos graxos saturados e insaturados, o que permite fracionar o óleo em dois principais componentes: fração líquida, a oleína de palma e fração sólida, a estearina. A degradação do óleo de palma durante armazenamento pode ser provocada pela ação da luz natural ou artificial, hidrólise autocatalítica, umidade, temperatura, material utilizado nas embalagens, ar e por micro-orga...

Strain induced ionic conductivity enhancement in epitaxial Ce0.9Gd0.1O22d

DEFF Research Database (Denmark)

Kant, K. Mohan; Esposito, Vincenzo; Pryds, Nini

2012-01-01

-plane ionic conductivity in CGO epitaxial thin films. The ionic conductivity is found to increase with decrease in buffer layer thickness. The tailored ionic conductivity enhancement is explained in terms of close relationships among epitaxy, strain, and ionic conductivity....

FRACIONAMENTO DE ÓLEOS DE CITROS UTILIZANDO FLUIDOS SUPERCRÍTICOS

Directory of Open Access Journals (Sweden)

Marisa MENDES

1997-12-01

Full Text Available O objetivo deste trabalho é o estudo sobre o fracionamento do óleo de laranja. Neste sentido, o limoneno e o linalol foram considerados os componentes-chaves do óleo de laranja, representando os terpenos e compostos oxigenados, respectivamente. Para modelar os dados de equilíbrio de fases foi usada a equação de estado de Peng-Robinson, juntamente com as regras de mistura de van der Waals, uni e biparamétrica, e de Panagiotopoulos e Reid. O uso desses modelos termodinâmicos permitiu determinar as condições de temperatura e pressão que levaram aos melhores valores do par seletividade-capacidade.The objective of this work is to study the fractionation of the citrus oils, especially orange oil. The orange oil is considered to be a mixture of two main components, limonene and linalool, which represent the terpenes and oxygenated group fractions, respectively. The Peng-Robinson equation of state using the van der Waals, with one or two parameters, and Panagiotopoulos and Reid mixing rules, were used to correlate and predict the binary and ternary high pressure phase equilibria of CO2 containing systems . The use of thermodynamic models to predict the phase equilibria allowed to establish the conditions of temperature and pressure, which led to the best results of selectivities and capacities of the extraction.

InAs migration on released, wrinkled InGaAs membranes used as virtual substrate

International Nuclear Information System (INIS)

Filipe Covre da Silva, S; Lanzoni, E M; De Araujo Barboza, V; Deneke, Ch; Malachias, A; Kiravittaya, S

2014-01-01

Partly released, relaxed and wrinkled InGaAs membranes are used as virtual substrates for overgrowth with InAs. Such samples exhibit different lattice parameters for the unreleased epitaxial parts, the released flat, back-bond areas and the released wrinkled areas. A large InAs migration towards the released membrane is observed with a material accumulation on top of the freestanding wrinkles during overgrowth. A semi-quantitative analysis of the misfit strain shows that the material migrates to the areas of the sample with the lowest misfit strain, which we consider as the areas of the lowest chemical potential of the surface. Material migration is also observed for the edge-supported, freestanding InGaAs membranes found on these samples. Our results show that the released, wrinkled nanomembranes offer a growth template for InAs deposition that fundamentally changes the migration behavior of the deposited material on the growth surface. (paper)

On the kinetic barriers of graphene homo-epitaxy

International Nuclear Information System (INIS)

Zhang, Wei; Yu, Xinke; Xie, Ya-Hong; Cahyadi, Erica; Ratsch, Christian

2014-01-01

The diffusion processes and kinetic barriers of individual carbon adatoms and clusters on graphene surfaces are investigated to provide fundamental understanding of the physics governing epitaxial growth of multilayer graphene. It is found that individual carbon adatoms form bonds with the underlying graphene whereas the interaction between graphene and carbon clusters, consisting of 6 atoms or more, is very weak being van der Waals in nature. Therefore, small carbon clusters are quite mobile on the graphene surfaces and the diffusion barrier is negligibly small (∼6 meV). This suggests the feasibility of high-quality graphene epitaxial growth at very low growth temperatures with small carbon clusters (e.g., hexagons) as carbon source. We propose that the growth mode is totally different from 3-dimensional bulk materials with the surface mobility of carbon hexagons being the highest over graphene surfaces that gradually decreases with further increase in cluster size

Estudo dos efeitos comportamentais, neuroquÃmicos e tÃxicos do Ãleo essencial de Zingiber officinale Roscoe

OpenAIRE

CÃcero Francisco Bezerra Felipe

2004-01-01

O Gengibre (Zingiber officinale Roscoe) Ã uma planta bastante apreciada em todo o mundo, nÃo apenas como um condimento, mas tambÃm por suas importantes propriedades medicinais. Os efeitos comportamentais e neuroquÃmicos do Ãleo essencial do gengibre - OEG foram estudados em camundongos tratados diariamente com o Ãleo essencial de gengibre (OEG 25, 50 e 100 mg/Kg, i.p. e v.o.). No sÃtimo dia de tratamento foram realizados os testes do labirinto em cruz elevado (LCE), campo aberto (CA), rota ro...

95 päeva sõjatandril, päevik tagataskus / Leo Kunnas ; interv. Erkki Bahovski

Index Scriptorium Estoniae

Kunnas, Leo, 1967-

2006-01-01

Kolonelleitnant Leo Kunnas räägib Iraagi sissisõjast ja oma raamatust "Viiv pikas sõjas. Märkmeid Iraagi sõjast", mis põhineb tema Iraagi-kogemustel. Vt. samas: Sõda, kus eestlane on sisside vastu

General Top-Down Ion Exchange Process for the Growth of Epitaxial Chalcogenide Thin Films and Devices

KAUST Repository

Xia, Chuan; Li, Peng; Li, Jun; Jiang, Qiu; Zhang, Xixiang; Alshareef, Husam N.

2016-01-01

) epitaxial chalcogenide metallic and semiconducting films and (2) free-standing chalcogenide films and (3) completed in situ formation of atomically sharp heterojunctions by selective ion exchange. Epitaxial NiCo2S4 thin films prepared by our process show 115

A new system to quantify uncertainties in LEO satellite position determination due to space weather events

Data.gov (United States)

National Aeronautics and Space Administration — We propose to develop a new system for quantitative assessment of uncertainties in LEO satellite position caused by storm time changes in space environmental...

Changes in the shapes of self-organized PbSe quantum dots during PbEuTe overgrowth investigated by anomalous X-ray diffraction

International Nuclear Information System (INIS)

Holy, V.; Schuelli, T.U.; Lechner, R.T.; Springholz, G.; Bauer, G.

2006-01-01

Anomalous X-ray diffraction was used for the investigation of shape and chemical composition of self-organized PbSe quantum dots covered by PbEuTe capping layers. From reciprocal-space maps of diffracted intensities measured at two energies of the primary radiation, we discriminated the contributions of the dot volumes and the surrounding crystal lattice to the diffracted intensity. We have found that the presence of Eu atoms suppresses the flattening of the dots during their overgrowth

Magnetic anisotropy basis sets for epitaxial (110) and (111) REFe2 nanofilms

International Nuclear Information System (INIS)

Bowden, G J; Martin, K N; Fox, A; Rainford, B D; Groot, P A J de

2008-01-01

Magnetic anisotropy basis sets for the cubic Laves phase rare earth intermetallic REFe 2 compounds are discussed in some detail. Such compounds can be either free standing, or thin films grown in either (110) or (111) mode using molecular beam epitaxy. For the latter, it is useful to rotate to a new coordinate system where the z-axis coincides with the growth axes of the film. In this paper, three symmetry adapted basis sets are given, for multi-pole moments up to n = 12. These sets can be used for free-standing compounds and for (110) and (111) epitaxial films. In addition, the distortion of REFe 2 films, grown on sapphire substrates, is also considered. The distortions are different for the (110) and (111) films. Strain-induced harmonic sets are given for both specific and general distortions. Finally, some predictions are made concerning the preferred direction of easy magnetization in (111) molecular beam epitaxy grown REFe 2 films

Raman investigation of GaP–Si interfaces grown by molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Bondi, A.; Cornet, C.; Boyer, S.; Nguyen Thanh, T.; Létoublon, A.; Pedesseau, L.; Durand, O. [Université Européenne de Bretagne, INSA, FOTON, UMR CNRS 6082, 20 Avenue des Buttes de Coësmes, F-35708 Rennes (France); Moreac, A. [Institut de Physique de Rennes, UMR-CNRS n°6251, Université Rennes1, Campus de Beaulieu — 35042 Rennes cedex (France); Ponchet, A. [CEMES, UPR CNRS 8011, F-31055 Toulouse (France); Le Corre, A. [Université Européenne de Bretagne, INSA, FOTON, UMR CNRS 6082, 20 Avenue des Buttes de Coësmes, F-35708 Rennes (France); Even, J., E-mail: jacky.even@insa.rennes.fr [Université Européenne de Bretagne, INSA, FOTON, UMR CNRS 6082, 20 Avenue des Buttes de Coësmes, F-35708 Rennes (France)

2013-08-31

Raman spectroscopy was used to investigate the residual strain in thin GaP layers deposited on Si substrates by molecular beam epitaxy. Different growth conditions were used to obtain a clean GaP–Si interface, including migration enhanced epitaxy. The strain induced Raman shifts of the longitudinal and the transverse optical GaP lattice modes were analyzed. The effects of crystalline defects are discussed, supported by high resolution transmission electron microscopy and X-ray scattering studies. Finally, Raman Spectroscopy reveals the presence of disorder (or surface)-activated optical phonons. This result is discussed in the light of surface morphology analyses. - Highlights: ► GaP thin layers grown by molecular beam epitaxy on Si substrates. ► Strain-induced Raman shifts of the optical GaP modes are analyzed. ► Simulation of optical GaP modes by density functional perturbation theory. ► Comparison with X-ray diffraction and electron and scanning probe microscopy data.

Epitaxial hexagonal materials on IBAD-textured substrates

Science.gov (United States)

Matias, Vladimir; Yung, Christopher

2017-08-15

A multilayer structure including a hexagonal epitaxial layer, such as GaN or other group III-nitride (III-N) semiconductors, a oriented textured layer, and a non-single crystal substrate, and methods for making the same. The textured layer has a crystalline alignment preferably formed by the ion-beam assisted deposition (IBAD) texturing process and can be biaxially aligned. The in-plane crystalline texture of the textured layer is sufficiently low to allow growth of high quality hexagonal material, but can still be significantly greater than the required in-plane crystalline texture of the hexagonal material. The IBAD process enables low-cost, large-area, flexible metal foil substrates to be used as potential alternatives to single-crystal sapphire and silicon for manufacture of electronic devices, enabling scaled-up roll-to-roll, sheet-to-sheet, or similar fabrication processes to be used. The user is able to choose a substrate for its mechanical and thermal properties, such as how well its coefficient of thermal expansion matches that of the hexagonal epitaxial layer, while choosing a textured layer that more closely lattice matches that layer.

Epitaxial growth of Ge-Sb-Te based phase change materials

International Nuclear Information System (INIS)

Perumal, Karthick

2013-01-01

Ge-Sb-Te based phase change materials are considered as a prime candidate for optical and electrical data storage applications. With the application of an optical or electrical pulse, they can be reversibly switched between amorphous and crystalline state, thereby exhibiting large optical and electrical contrast between the two phases, which are then stored as information in the form of binary digits. Single crystalline growth is interesting from both the academic and industrial perspective, as ordered Ge-Sb-Te based metamaterials are known to exhibit switching at reduced energies. The present study deals with the epitaxial growth and analysis of Ge-Sb-Te based thin films. The first part of the thesis deals with the epitaxial growth of GeTe. Thin films of GeTe were grown on highly mismatched Si(111) and (001) substrates. On both the substrate orientations the film grows along [111] direction with an amorphous-to-crystalline transition observed during the initial stages of growth. The amorphous-to-crystalline transition was studied in-vivo using azimuthal reflection high-energy electron diffraction scans and grazing incidence X-ray diffraction. In the second part of the thesis epitaxy and characterization of Sb 2 Te 3 thin films are presented. The third part of the thesis deals with the epitaxy of ternary Ge-Sb-Te alloys. The composition of the films are shown to be highly dependent on growth temperatures and vary along the pseudobinary line from Sb 2 Te 3 to GeTe with increase in growth temperatures. A line-of-sight quadrupole mass spectrometer was used to reliably control the GeSbTe growth temperature. Growth was performed at different Ge, Sb, Te fluxes to study the compositional variation of the films. Incommensurate peaks are observed along the [111] direction by X-ray diffraction. The possibility of superstructural vacancy ordering along the [111] direction is discussed.

Tensão superficial estática de soluções aquosas com óleos minerais e vegetais utilizados na agricultura Surface tension of mineral oils and vegetable oils

Directory of Open Access Journals (Sweden)

Cristina G. de Mendonça

2007-01-01

Full Text Available O trabalho teve como objetivo avaliar a tensão superficial estática de soluções aquosas com formulações de óleos minerais e vegetais emulsionáveis utilizados como adjuvantes na agricultura. Os óleos minerais e vegetais, quando adicionados aos produtos fitossanitários, podem imprimir características desejáveis à calda de pulverização, como reduzir a tensão superficial em soluções aquosas, possibilitar maior contato da calda com a superfície vegetal ou reduzir o potencial de deriva durante as pulverizações. Foram testados os seguintes produtos comerciais: óleos minerais (Assist, Attach, Dytrol, Iharol, Mineral Oil, Spinner, Sunspray-E e Triona e óleos vegetais (Agrex'oil Vegetal, Crop Oil, Natur'l Óleo, Óleo Vegetal Nortox e Veget Oil, todos com registro de uso na agricultura. A tensão superficial das soluções aquosas foi avaliada em 11 concentrações para cada produto (0,025; 0,05; 0,1; 0,25; 0,5; 0,75; 1,0; 1,5; 2,0; 2,5 e 3,0% v/v. Essa propriedade dos óleos minerais e dos óleos vegetais foi estimada medindo-se a massa das gotas formadas na extremidade de uma bureta. Ao conjunto de dados obtidos para cada produto, na avaliação da tensão superficial, foram determinadas as análises de variância e de regressão, ajustando-se os dados ao Modelo de Mitscherlich. Entre os óleos minerais, destacaram-se os produtos: Assist, Dytrol, Iharol e Mineral Oil por apresentarem as menores tensões superficiais mínimas estimadas pelo Modelo, respectivamente, 29,255; 28,442; 26,097 e 28,584 mN m-1. Os óleos vegetais que apresentaram os menores valores de tensão superficial mínima estimados pelo Modelo, foram: Agrex' oil Vegetal (27,716 mN m-1, Natur'l óleo (28,216 mN m-1, Veget Oil (27,308 mN m-1 e Crop Oil (29,964 mN m-1.The aim of this work was to evaluate the surface tension of water emulsion with mineral oils and vegetable oils used as adjuvant. The mineral and vegetable oils when added to the agrochemicals can

Investigation of epitaxial silicon layers as a material for radiation hardened silicon detectors

International Nuclear Information System (INIS)

Li, Z.; Eremin, V.; Ilyashenko, I.; Ivanov, A.; Verbitskaya, E.

1997-12-01

Epitaxial grown thick layers (≥ 100 micrometers) of high resistivity silicon (Epi-Si) have been investigated as a possible candidate of radiation hardened material for detectors for high-energy physics. As grown Epi-Si layers contain high concentration (up to 2 x 10 12 cm -3 ) of deep levels compared with that in standard high resistivity bulk Si. After irradiation of test diodes by protons (E p = 24 GeV) with a fluence of 1.5 x 10 11 cm -2 , no additional radiation induced deep traps have been detected. A reasonable explanation is that there is a sink of primary radiation induced defects (interstitial and vacancies), possibly by as-grown defects, in epitaxial layers. The ''sinking'' process, however, becomes non-effective at high radiation fluences (10 14 cm -2 ) due to saturation of epitaxial defects by high concentration of radiation induced ones. As a result, at neutron fluence of 1 x 10 14 cm -2 the deep level spectrum corresponds to well-known spectrum of radiation induced defects in high resistivity bulk Si. The net effective concentration in the space charge region equals to 3 x 10 12 cm -3 after 3 months of room temperature storage and reveals similar annealing behavior for epitaxial as compared to bulk silicon