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21.
Dorodame Moura Leito 《Journal of Polymer Science.Polymer Physics》1972,10(6):1111-1117
The permeation and solubility of propylene in polyethylene films were measured at temperatures and pressures near the condensation point of the vapor. Diffusion coefficients were calculated from these data. On the basis of the behavior of activation energies with relative vapor pressure, it is shown how diffusion and sorption influence permeation phenomena in this region. 相似文献
22.
Adams J Aggarwal MM Ahammed Z Amonett J Anderson BD Arkhipkin D Averichev GS Badyal SK Bai Y Balewski J Barannikova O Barnby LS Baudot J Bekele S Belaga VV Bellwied R Berger J Bezverkhny BI Bharadwaj S Bhasin A Bhati AK Bhatia VS Bichsel H Billmeier A Bland LC Blyth CO Bonner BE Botje M Boucham A Brandin AV Bravar A Bystersky M Cadman RV Cai XZ Caines H Calderón de la Barca Sánchez M Carroll J Castillo J Cebra D Chajecki Z Chaloupka P Chattopdhyay S Chen HF Chen Y Cheng J Cherney M Chikanian A 《Physical review letters》2004,93(25):252301
Results on high transverse momentum charged particle emission with respect to the reaction plane are presented for Au + Au collisions at square root s(NN)=200 GeV. Two- and four-particle correlations results are presented as well as a comparison of azimuthal correlations in Au + Au collisions to those in p + p at the same energy. The elliptic anisotropy v(2) is found to reach its maximum at p(t) approximately 3 GeV/c, then decrease slowly and remain significant up to p(t) approximately 7-10 GeV/c. Stronger suppression is found in the back-to-back high-p(t) particle correlations for particles emitted out of plane compared to those emitted in plane. The centrality dependence of v(2) at intermediate p(t) is compared to simple models based on jet quenching. 相似文献
23.
Maria Raquel Cavalcanti Inácio Maria de Fátima Vitória de Moura Kássio Michell Gomes de Lima 《Vibrational Spectroscopy》2011,57(2):342-345
This paper proposes a methodology for the classification and determination of total protein in milk powder using near infrared reflectance spectrometry (NIRS) and variable selection. Two brands of milk powder were acquired from three Brazilian cities (Natal-RN, Salvador-BA and Rio de Janeiro-RJ). The protein content of 38 samples was determined by the Kjeldahl method and NIRS analysis. Principal component regression (PCR) and partial least squares (PLS) multivariate calibrations were used to predict the total protein. Soft independent modeling of class analogy (SIMCA) was also used for full-spectrum classification, resulting in almost 100% classification accuracy, regardless of the significance level adopted for the F-test. Using this strategy, it was feasible to classify powder milk rapidly and nondestructively without the need for various analytical determinations. Concerning the multivariate calibration models, the results show that PCR, PLS and MLR-SPA models are good for predicting total protein in powder milk; the respective root mean square errors of prediction (RMSEP) were 0.28 (PCR), 0.25 (PLS), 0.11 wt% (MLR-SPA) with an average sample protein content of 8.1 wt%. The results obtained in this investigation suggest that the proposed methodology is a promising alternative for the determination of total protein in milk powder. 相似文献
24.
O. V. Vikhrova Yu. A. Danilov B. N. Zvonkov A. V. Kudrin V. V. Podol’skiĭ Yu. N. Drozdov M. V. Sapozhnikov C. Moura M. I. Vasilevskiy M. P. Temiryazeva 《Physics of the Solid State》2008,50(1):52-55
The InMnAs layers with ferromagnetic properties at room temperature are prepared by laser ablation. This is confirmed by the results of investigating the anomalous Hall and magneto-optical Kerr effects and by magnetic-force microscopy. According to x-ray diffraction data, the InMnAs layers have a fairly high crystal quality but contain inclusions of the MnAs hexagonal phase. An analysis of the electrical properties of the InMnAs layers suggests that the ferromagnetism revealed at room temperature cannot be accounted for by the presence of the MnAs phase but is associated with the charge carrier transfer in the InMnAs matrix. 相似文献
25.
Layered stable equilibria of a reaction-diffusion equation with nonlinear Neumann boundary condition
Arnaldo Simal do Nascimento Renato José de Moura 《Journal of Mathematical Analysis and Applications》2008,347(1):123-135
In this work we investigate the existence and asymptotic profile of a family of layered stable stationary solutions to the scalar equation ut=ε2Δu+f(u) in a smooth bounded domain Ω⊂R3 under the boundary condition εν∂u=δεg(u). It is assumed that Ω has a cross-section which locally minimizes area and limε→0εlnδε=κ, with 0?κ<∞ and δε>1 when κ=0. The functions f and g are of bistable type and do not necessarily have the same zeros what makes the asymptotic geometric profile of the solutions on the boundary to be different from the one in the interior. 相似文献
26.
The flow activation free energy ( ΔG *) is the minimum energy necessary to induce a flow in a system that is at rest. It can be calculated from the system viscosity using the Andrade--Eyring theory. In the present work the flow activation free energy of cholesteric lyotropic liquid crystals was studied as a function of D-(+)-mannose concentration added to a nematic mesophase. The results obtained showed that all the systems can be characterized as Newtonian, but a smooth time-dependent effect can be observed mainly in systems with a lower chiral inductor concentration. It has also been observed that an increase of cholestericity leads to a decrease of ΔH * values until a limit is reached at 1 mol % of inductor. From a positive ΔS * variation it was possible to verify the existence of a locally less organized transient state during the process of micellar diffusion. When the cholesterization process was considered, the increase of the inductor concentration leads to a decrease of ΔS * and consequently to a system, as a whole, more orderly, possibly as a result of the restriction of movement caused by the presence of chiral interactions. 相似文献
27.
Time and temperature induced phase transformation in L‐isoleucine hydrochloride monohydrated crystal
Ricardo S. Ferreira Júnior Geanso M. Moura Andreia C. Pereira Paulo R. da Silva Ribeiro Luzeli M. da Silva Adenilson O. dos Santos 《Crystal Research and Technology》2016,51(12):738-741
Semi organic crystals have been intensively studied aiming applications in nonlinear optical (NLO). Such applicability requires crystals with both high quality and thermal stability, which make the full characterization of this material a topic issue. In this paper, single crystals of L‐isoleucine hydrochloride monohydrated (L‐Ile.H2O.HCl) was synthesized by slow evaporation technique and characterized by thermal analysis and X‐ray diffraction (XRD) measurements. XRD results at 298 K showed that the sample crystallize with the orthorhombic structure, and the lattice parameters obtained by Rietveld refinement were a = 5.873(3) Å, b = 24.814(4) Å, and c = 6.873(5) Å. Thermal analysis measurements shows four decomposition stages between 328 ‐480 K which were associated with loss of water by desolvation, loss crystallization water and decomposition of L‐Ile.HCl. XRD measurements as a function of temperature up to 428 K show an irreversible phase transformation. This transformation was obtained after 32 hours keeping the L‐Ile.HCl.H2O sample at 413 K. The analysis shows that phase transformation occurs due to water and chlorine losses without destroy the amino acid carbon chain and in the end of transformation only the precursor amino acid remains. L‐Ile.HCl.H2O present low thermal stability and the phase transformation is time and temperature dependent. 相似文献
28.
Thales R. de Moura Sahra L. Cavalcanti Paulo R. D. V. de Godoy Elza T. Sakamoto-Hojo Fillipe V. Rocha Eduardo T. de Almeida Victor M. Deflon Antonio E. Mauro Adelino V. G. Netto 《Transition Metal Chemistry》2017,42(6):565-574
Complexes of the type cis-[PdX2(imzt)(PPh3)] {imzt = imidazolidine-2-thione; PPh3 = triphenylphosphine; X = Cl (1), Br (2), I (3), SCN (4)} have been synthesized and characterized by elemental analyses, molar conductance, IR and 1H NMR spectroscopies. The complex 1·MeOH was obtained from the reaction of [PdCl2(CH3CN)2], imidazolidine-2-thione and triphenylphosphine in CHCl3/CH3OH. Complexes 2·MeOH, 3 and 4 were prepared by metathesis of the chlorido ligands in 1 with bromide, iodide and thiocyanate, respectively. Elemental analyses showed good agreement with the expected mononuclear compositions, while the molar conductivities of the complexes in DMF were consistent with their nonelectrolytic nature. NMR spectra confirmed coordination of the imidazolidine-2-thione and triphenylphosphine ligands. Single-crystal X-ray diffraction determination of 1·CH3OH showed that the coordination geometry around PdII is nearly square planar, with the chlorido ligands in a cis configuration. All four complexes have been tested in vitro by XTT assay for their cytotoxicity against human glioblastoma cell line (U87MG). The binding of 1 with guanosine was studied by 1H NMR spectroscopy, revealing that the coordination takes place via N7. 相似文献
29.
Elisana Afonso Moura Lidiane Pinto Correia Márcia Ferraz Pinto José Valdilânio Virgulino Procópio Fábio Santos de Souza Rui Oliveira Macedo 《Journal of Thermal Analysis and Calorimetry》2010,100(1):289-293
This article had studied the thermal characterization of the raw material and different fluconazole crystals, obtained through
recrystallization with different solvents using thermoanalytical techniques (TG, DTA, DSC-50, DSC Photovisual, DSC-60) and
Pyr-GC/MS. The results confirmed that the fluconazole volatilizes without decomposition until 250 °C. Pyr-GC/MS showed hexachlorobenzene
like impurities in fluconazole raw material. 相似文献
30.
Marli Roehsig Daniela Mendes Louzada de Paula Sidnei Moura Edna Maria de Albuquerque Diniz Mauricio Yonamine 《Journal of separation science》2010,33(14):2115-2122
A number of fatty acid ethyl esters (FAEEs) have recently been detected in meconium samples. Several of these FAEEs have been evaluated as possible biomarkers for in utero ethanol exposure. In the present study, a method was optimized and validated for the simultaneous determination of eight FAEEs (ethyl laurate, ethyl myristate, ethyl palmitate, ethyl palmitoleate, ethyl stearate, ethyl oleate, ethyl linoleate and ethyl arachidonate) in meconium samples. FAEEs were extracted by headspace solid‐phase microextraction. Analyte detection and quantification were carried out using GC‐MS operated in chemical ionization mode. The corresponding D5‐ethyl esters were synthesized and used as internal standards. The LOQ and LOD for each analyte were <150 and <100 ng/g, respectively. The method showed good linearity (r2>0.98) in the concentration range studied (LOQ – 2000 ng/g). The intra‐ and interday imprecision, given by the RSD of the method, was lower than 15% for all FAEEs studied. The validated method was applied to 63 authentic specimens. FAEEs could be detected in alcohol‐exposed newborns (>600 ng/g cumulative concentration). Interestingly, FAEEs could also be detected in some non‐exposed newborns, although the concentrations were much lower than those measured in exposed cases. 相似文献