47,747 research outputs found
Fibras de vidro a base de Li20 - Zr02 - BaO - Si02 recobertas com Nb205 para utilização em micro-extração em fase sólida
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-graduação em QuímicaNeste trabalho são descritas as metodologias para obtenção e modificações da superfície de fibras de vidro de composição Li2O-ZrO2-BaO-SiO2. Apresenta-se também as aplicações destas fibras na determinação, por SPME, de fenol e de uma mistura de álcoois. Para obtenção das fibras de vidro construiu-se um equipamento, o qual baseia-se na técnica de estiramento. As fibras de vidro foram recobertas utilizando-se duas técnicas: Decomposição de Organometálicos, onde o etóxido de nióbio (V) foi empregado como reagente precursor do óxido de nióbio (V), e Deposição de Vapor Químico, na qual fez-se uso do cloreto de nióbio como precursor do óxido de nióbio (V).Utilizou-se da técnica de Microscopia Eletrônica de Varredura para avaliar a morfologia das fibras sem recobrimento e recobertas. O recobrimento com óxido de nióbio sobre a superfície das fibras foi estudado pela técnica de "Color Map" e as análises químicas realizadas pela Microssonda de Energia Dispersiva, ambas as técnica acopladas ao MEV. A Técnica de Micro-extração em Fase Sólida foi utilizada para avaliar a capacidade de adsorsão de compostos polares e apolares pelas fibras recobertas. Com os resultados obtidos, verficou-se que pela técnica de CVD obtem-se fibras com um recobrimento mais homogêneo e espesso. Estas fibras apresentaram melhor eficiência no processo de adsorção como verificado pelos resultados cromatográficos
[Letter from Arthur S. Rosichan to J. L. Zuber - August 11, 1944]
No full textLetter from Arthur S. Rosichan to J. L. Zuber: August 11, 1944. Subject of the letter is the author moving to Houston to work for the Jewish Community Council
Macrocheles embersoni Azevedo, Castilho & Berto, n. sp.
No full textMacrocheles embersoni Azevedo, Castilho & Berto, n. sp. Adult female (Fig. 2–11). Five specimens measured. Gnathosoma. Fixed cheliceral digit 105 (100–110) long, with three teeth in addition to apical tooth and a setiform pilus dentilis (Fig. 2); movable digit 92 (90–95) long, with three teeth in addition to apical tooth; antiaxial and dorsal lyrifissures as well as dorsal seta distinct. Arthrodial process of chelicera double brush-shaped. Numbers of setae on palp trochanter, femur and genu 2–5–6; all setiform; apotele three-tined. Epistome with a distally bifurcate anteromedian extension flanked by a pair of shorter distally expanded anterolateral extensions (Fig. 3). Hypostome microtuberculate; deutosternum with six roughly transverse lines, the most distal smooth, others multidenticulate (Fig. 4). Internal malae fused, with external margin fimbriate. Corniculus horn-shaped, about twice as long as its basal width. Seta h 3 about in longitudinal line with h 1, mesad of and slightly anteriad of h 2. Measurements of setae: h 1 68 (60–73), h 2 36 (28–43), h 3 95 (88–100), sc 37 (33–43); all aciculate and smooth. Dorsal idiosoma (Fig. 5). Idiosoma 900 (870–950) long and 600 (570–650) wide at widest level. Dorsal shield reticulate (except in central region of podonotal region, smooth) and punctate; 815 (735–830) long and 520 (483– 542) wide at level of coxa III, attenuate posteriorly; with 28 pairs of setae (j 1– j 6, z 1, z 2, z 5, z 6, s 2– s 6, r 2– r 4, J 2, J 5, Z 1, Z 3– Z 5, S 1, S 2, S 4 and S 5) and 22 pairs of distinguishable pores; with a cell-like depression (cj 3) between j 2 and j 3; with procurved line well developed posteriad of j 6, z 6, s 5 and r 4; with a posterior depression encompassing pore pZ5 and insertions of J5 and Z 5. Unsclerotised cuticle laterad of dorsal shield with nine pairs of setae (r 5, r 6, R 1–6 and R x). Measurements of setae: j 1 44 (41–48); j 2 57 (50–65); j 3 63 (58–64); j 4 65 (60–70); j 5 67 (63–70); j 6 43 (38–48); z 1 19 (14–25); z 2 65 (57–70); z 5 42 (39–45); z 6 51 (45–55); s 2 53 (47–60); s 3 64 (58–67); s 4 71 (62– 75); s 5 66 (60–75); s 6 65 (55–72); r 2 62 (57–67); r 3 63 (57–67); r 4 58 (51–65); r 5 30 (20–35); r 6 27 (25–30); J 2 45 (40–50); J 5 29 (21–33); Z 1 67 (60–75); Z 3 61 (50–65); Z 4 60 (50–65); Z 5 59 (51–67); S 1 53 (50–57); S 2 61 (52–70); S 4 68 (57–75); S 5 67 (59–76); R 1 29 (25–35); R 2 33 (28–40); R 3 38 (33–43); R 4 38 (33–43); R 5 43 (38– 45); R6 48 (43–55); R x 53 (48–55). All setae distinctly pilose distally (Fig. 6), r 6 aciculate and smooth; j 1 stouter than other setae and with remote insertions. Ventral idiosoma (Fig. 7). Base of tritosternum 54 (43–65) long and 24 (23–25) wide proximally; laciniae 117 (95–133) long, pilose (Fig. 8). Sternal shield with micropunctations and lines l. m. t., l. o. a. and l. o. p.; a. p. p. absent; 123 (120–125) long and 170 (162–183) wide at level of coxae II; with three pairs of setae and two pairs of lyrifissures. Seta st 4 and associated lyrifissure on metasternal platelet. Epigynal shield with micropunctations; 149 (138–155) long and 147 (133–158) wide at widest level, posterior margin straight; with a pair of accessory sclerites and with a pair of epigynal setae (st 5). Ventrianal shield with micropunctations and semiconcentric lines; 245 (220– 262) long and 187 (165–203) wide at widest level; with three pairs of pre-anal setae (Jv 1, Jv 2 and Jv 3) in addition to circum-anal setae; without distinguishable pores. Opisthogastric unsclerotised cuticle with seven pairs of setae (Jv 4, Jv 5 and Zv 1- Zv5). Peritreme extending anteriorly almost to level of z 1; with two pairs of lyrifissures (at level of posterior margin of coxa III and at level of coxa I) (Fig. 9). Peritrematic shield restricted to the length of peritreme, fused to dorsal shield at level of z 4; with one pair of pores next to posterior tip of peritreme and one pair of pores at level of median region of coxa II; one pair of lyrifissures at level of posterior margin of coxa III. Cribral glands tuberculate and easily discernible at the cribral margins. Measurements of setae: st 1 56 (50–60); st 2 56 (50– 58); st 3 53 (47–58); st 4 45 (43–50); st 5 44 (43–48); Jv 1 39 (33–42); Jv 2 38 (30–42); Jv 3 33 (30–38); Jv 4 33 (30– 35); Jv 5 32 (30–35); Zv 1 30 (23–38); Zv 2 33 (28–35); Zv 3 33 (28–35); Zv 4 34 (28–38); Zv 5 46 (40–55); para-anal 37 (35–40); post-anal 11 (10–13). All ventral idiosomal setae aciculate and smooth. Spermathecal apparatus (Fig. 10). Similar to that of Macrocheles robustulus Berlese, illustrated by Costa (1966). Solenostome apparently opening at posteromedian margin of base of coxa III; infundibulum discreet. Sacculus foeminus consisting of two globular structures connected by a broad passage; tubulus annulatus meeting each globular structure via cone-shaped ramus sacculus; cornu sacculus thick-walled at region near sacculus foeminus, continuing as a narrow duct that flares distally into a rugose structure. Legs. Length of legs (except ambulacrum): I, 620 (600–650); II, 654 (560–750); III, 676 (630–720); and IV, 1000 (920–1060). Chaetotaxy (coxa–tibia), I: 0 0/2 0/0 0, 1 0/1 1/1 1, 1 3/2 2/3 2, 3 2/2 1/1 2, 3 2/2 1/2 2; II: 0 0/1 0/1 0, 1 0/1 0/2 1, 2 3/1 2/2 1, 2 3/1 2/1 2, 2 2/1 2/1 2; III: 0 0/1 0/1 0, 1 1/2 0/0 1, 1 3/1 0/0 1, 1 2/1 2/0 1, 1 2/1 1/1 1; IV: 0 0/1 0/0 0, 1 1/2 0/1 0, 1 2/1 1/0 1, 1 2/1 1/0 1 (Fig. 11), 1 2/1 1/1 1. Tarsi II–IV with 18 setae each. Tarsus I without ambulacrum and claw; tarsi II–IV with well developed ambulacra and claws. Material examined. Holotype female and four paratype females from accumulations of dung at “Fazenda Paraíso” (22°27’20’’S; 49°20’15’’W), Cabrália Paulista, São Paulo state, Brazil, 24 March 2014. All types collected by L.H. Azevedo and deposited at Departamento de Entomologia e Acarologia, Escola Superior de Agricultura “ Luiz de Queiroz ” (ESALQ), Universidade de São Paulo (USP), Piracicaba, São Paulo state, Brazil. Etymology. The specific name embersoni is in honour of Dr. Rowan Mark Emberson, Lincoln University, Canterbury, New Zealand, for his extensive contributions to the taxonomy of Macrochelidae. Remarks. Macrocheles embersoni is similar to species of the woodruffi cluster of the dimidiatus complex of the dimidiatus species group (Krantz, 2007), mainly by having the dorsal shield attenuated posteriorly and with procurved line; j l pectinate and stouter than j 2; and ventrianal shield very small, with transverse section of anterior margin shorter than posterior margin of epigynal shield, with rounded anterolateral corners. Macrocheles embersoni is similar to Macrocheles spickai Krantz & Whitaker, 1988 but females of the latter species have unsclerotised cuticle laterad of dorsal shield with 10 pairs of setae (r 5– r 6, R 1–6 and two R x), sternal shield with l. ang. and a. p. p. present, and ventral idiosomal setae pilose distally. The species of this group are a strongly cohesive assemblage not only morphologically, but also geographically and behaviourally. Members of the group are confined to the New World, with the vast majority of species being found in the neotropics (Krantz, 2007).Published as part of Azevedo, Letícia H., Castilho, Raphael C., Berto, Marielle M. & De Moraes, Gilberto J., 2017, Macrochelid mites (Mesostigmata: Macrochelidae) from São Paulo state, Brazil, with description of a new species of Macrocheles, pp. 413-426 in Zootaxa 4269 (3) on pages 416-418, DOI: 10.11646/zootaxa.4269.3.5, http://zenodo.org/record/58248
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
Effect of heat treatment on fatigue behavior of as-built notched Co-Cr-Mo parts produced by Selective Laser Melting
No full textIn this paper Cobalt-Chromium-Molybdenum (Co-Cr-Mo) specimens produced by Selective Laser Melting (SLM) for biomedical field were studied. In particular, fatigue tests were carried out comparing as-built condition with Hot Isostatic Pressing (HIP) and a heat treatment under vacuum condition. The influence on microstructure and fatigue properties was investigated on plain specimens and with a V-notched geometry. Both vacuum heat treatment and HIP had effects on the microstructure and internal defects, which resulted in an enhancement of quasi-static and fatigue properties. Lastly, notch sensitivity and applicability of ASED failure criterion for fatigue life prediction notched specimens were evaluated
Applicability of strain energy density criterion for fracture prediction of notched PLA specimens produced via fused deposition modeling
No full textThe Averaged Strain Energy Density (ASED) criterion is validated for the failure prediction of notched Polylactide Acid specimens fabricated by Fused Deposition Modeling by means of experimental data and the results are compared to the Theory of Critical Distances. The common approach of estimating the ASED control volume radius based on the measured fracture toughness was shown to be suboptimal, arguably because of the difficulties of obtaining the fracture toughness with such complex materials. Therefore, a more robust approach is evaluated in analogy of the TCD and it is shown to successfully extend the range of applicability of the ASED criterion. © 2021 The Author(s
Precision measurements of B[psi(3686) -> pi(+)pi(-)J/psi] and B[J/psi -> l(+)l(-)]
No full text<p>Based on (106.41 +/- 0.86) x 10(6) psi(3686) events collected with the BESIII detector at the BEPCII collider, the branching fractions of psi(3686) -> pi(+)pi(-)J/psi, J/psi -> e(+)e(-), and J/psi -> mu(+)mu(-) are measured. We obtain B[psi(3686) -> pi(+)pi(-)J/psi] = (34.98 +/- 0.02 +/- 0.45)%, B[J/psi -> e(+)e(-)] = (5.983 +/- 0.007 +/- 0.037)%, and B[J/psi -> mu(+)mu(-)] = (5.973 +/- 0.0007 +/- 0.038)%. The measurement of B[psi(3686) -> pi(+)pi(-)J/psi] confirms the CLEO-c measurement, and is apparently larger than the others. The measured J/psi leptonic decay branching fractions agree with previous experiments within one standard deviation. These results lead to B[J/psi -> l(+)l(-)] = (5.978 +/- 0.005 +/- 0.040)% by averaging over the e(+)e(-) and mu(+)mu(-) channels and a ratio of B[J/psi -> e(+)e(-)]/B[J/psi -> mu(+)mu(-)] = 1.0017 +/- 0.0017 +/- 0.0033, which tests e- mu universality at the four tenths of a percent level. All the measurements presented in this paper are the most precise in the world to date.</p>
Strain energy density approach as fatigue assessment of Ti6Al4V specimens machined by WEDM single step technology
No full textThe present paper summarizes the results from force-controlled fatigue tests performed on Ti6Al4V specimens machined by wire electrical discharge machining (WEDM) single step technology. For this aim, blunt V-notched specimens with various notch root radii and un-notched “dog bone” specimens are considered. The fatigue behaviour of this alloy machined by WEDM single step technology is an extremely important issue but, despite this, the literature on this topic is very poor and the effect of geometrical discontinuities on the fatigue life of has still to be investigated. Fatigue data, generated by testing a total number of 62 specimen, are re-analysed by means of the Strain Energy Density (SED) method, investigating the possibility to use this method following a numerical approach. Estimation of the critical radius is performed on the basis of finite element analysis to overcome the lack of knowledge of the material properties often related to the machining process. Thanks to the SED method, it is possible to summarize in a single scatter-band all the collected fatigue data, independently of the specimen geometry. The proposed numerical approach is capable to reduce the scatter index compared to the actual procedure with modest extra effort, also solving the issue related to the geometry selection for the critical radius identification. The method is successfully validated by assessing the fatigue life of specimens with two notch geometries not considered during the critical radius identification. © 2022 The Author(s
Fatigue tests and fatigue-life prediction models for hybrid welded-bolted demountable shear connectors
No full textFour push out tests were conducted to assess the structural performance of a welded demountable shear connector (WDSC) under high-cycle fatigue loading. The primary failure mode observed was stud fracture at the base. The presence of grout inside the tube significantly increased the WDSC's fatigue life by 5.4 times. The study also analysed stiffness degradation and relative slip evolution during fatigue cycles. Two finite element-based approaches were employed for fatigue life prediction: the critical plane method for fatigue crack initiation life and fracture mechanics for crack propagation life. Based on the experimental and numerical results, fatigue life prediction formulas (Wöhler curves) are proposed for WDSCs with and without grout to aid in predicting fatigue failure in fatigue-sensitive structural designs
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