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排序方式: 共有77条查询结果,搜索用时 15 毫秒
41.
Anna Carolina da Silva Alana Emília Soares de França Queiroz Talita Camila Evaristo dos Santos Nascimento Cristine Rodrigues José Erick Galindo Gomes Cristina Maria Souza-Motta Luciana Porto de Souza Vandenberghe Erika Valente de Medeiros Keila Aparecida Moreira Polyanna Nunes Herculano 《Applied biochemistry and biotechnology》2014,173(7):1652-1666
Of the many reported applications for xylanase, its use as a food supplement has played an important role for monogastric animals, because it can improve the utilisation of nutrients. The aim of this work was to produce xylanase by extractive fermentation in an aqueous two-phase system using Aspergillus tamarii URM 4634, increasing the scale of production in a bioreactor, partially characterising the xylanase and evaluating its influence on monogastric digestion in vitro. Through extractive fermentation in a bioreactor, xylanase was obtained with an activity of 331.4 U mL?1 and 72 % yield. The xylanase was stable under variable pH and temperature conditions, and it was optimally active at pH 3.6 and 90 °C. Xylanase activity potentiated the simulation of complete monogastric digestion by 6 %, and only Mg2+ inhibited its activity. This process provides a system for efficient xylanase production by A. tamarii URM 4634 that has great potential for industrial use. 相似文献
42.
Crossley EL Issa F Scarf AM Kassiou M Rendina LM 《Chemical communications (Cambridge, England)》2011,47(44):12179-12181
New 1,2-closo- and 7,8-nido-carboranylpyrazolopyrimidines bind to the translocator protein (TSPO) with high affinity, providing the first evidence of a unique two-site binding profile for the closo-carborane derivative. The boron-rich compounds can also deliver boron to human glioma cells far more effectively than clinical agents used in boron neutron capture therapy (BNCT). 相似文献
43.
Kouznetsov DA Arkhangelsky SE Berdieva AG Khasigov PZ Orlova MA 《Isotopes in environmental and health studies》2004,40(3):221-227
A simple and efficient preparative electrophoretic technique has been proposed to obtain a modified creatine kinase (CK, E.C.2.7.3.2) molecule with an increased content of 25Mg in the active site. A key point of the method is the special design of a 0.9 x 12.0 cm column for ascendent electrophoresis, packed consecutively, from the bottom to the top, with layers of 30 % PAAG (polyacrylamide grade), 25Mg2+ -containing 7.5 % PAAG, enzyme-binding ADP Sepharose and 2.2 % agarose gels, based on different tris-glycine and tris-HCl separation buffer systems. The isotope substitution process was a result of simultaneous desorption of enzyme from ADP Sepharose and electrically directed extensive flow of 25Mg2+ cations through the porous gel matrix. Greater than 8-fold 25Mg enrichment, i.e. a 10.2-86.3 % increase of 25Mg contribution to total enzyme magnesium, has been reached. The modified 25Mg-rich CK samples manifest higher (2.4-fold increase) values of specific catalytic activity when compared with intact (control) ones. 相似文献
44.
Simorellis AK Flynn PF 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,170(2):267-328
Pulsed gradient simulated-echo (PGSE) NMR diffusion measurements provide a facile and accurate means for determining the self-diffusion coefficients for molecules over a wide range of sizes and conditions. The measurement of diffusion in solvents of low intrinsic viscosity is particularly challenging, due to the persistent presence of convection. Although convection can occur in most solvent systems at elevated temperatures, in lower viscosity solvents (e.g., short chain alkanes), convection may manifest itself even at ambient laboratory temperatures. In most circumstances, solvent suppression will also be required, and for solvents that have multiple resonances, effective suppression can likewise represent a substantial challenge. In this article, we report an NMR experiment that combines a double-stimulated echo PFG approach with a WET-based solvent suppression scheme that effectively and simultaneously address the issues of dynamic range and the deleterious effects of convection. The experiment described will be of general benefit to studies aimed at the characterization of diffusion of single molecules directly dissolved in low-viscosity solvents, and should also be of substantial utility in studies of supramolecular assemblies such as reverse-micelles dissolved in apolar solvents. 相似文献
45.
Letícia F. da Silva Celito C. Guerra Alana Foresti Ana M. Bergold 《Chemical Papers》2017,71(3):661-672
Quantification of bioactive phenols, like stilbenes and flavonols (SaF), has been conducted to evaluate the nutraceutical potential of red wines. However, there is still a lack of full validated, fast and accessible liquid chromatography methods offering high selectivity and a simple procedure. We present here the use of a high-resolution mass spectrometer to evaluate the selectivity of a feasible and traditional liquid chromatography technique (HPLC–DAD) to analyze markers of aglycone SaF in red wines. The SaF compounds were tested: trans-resveratrol, trans-ε-viniferin, quercetin, myricetin, and kaempferol, as well as trans-cinnamic acid, one of their precursors. System suitability and validation tests were employed for the selected conditions (octylsilane column, methanol mobile phase, and gradient elution). The validation process ensured the HPLC–DAD method was selective, linear, sensitive, precise, accurate and robust. The method was then applied to red wine samples from the Campanha Gaúcha region, Southern Brazil. The real samples contained different SaF levels, showing that the method is applicable to routine use. Furthermore, this was the first SaF characterization of red wines from the Campanha Gaúcha, contributing to regional and product development. 相似文献
46.
da Silva Daniel J. da Silva Barbosa Rennan F. de Souza Alana G. Ferreira Rafaela R. Camani Paulo H. Nantes-Cardoso Iseli L. Rosa Derval S. 《Cellulose (London, England)》2021,28(12):8153-8175
Cellulose - In this work, we developed bactericidal cotton fabrics treated with ZnO and Cu2+, with citric acid as a binder and reduction agent, via microwave irradiation. Fabrics were characterized... 相似文献
47.
Julia J. Chang Andrew Martin Chuanshen Du Alana M. Pauls Martin Thuo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(38):16488-16493
Fabrication of bio-templated metallic structures is limited by differences in properties, processing conditions, packing, and material state(s). Herein, by using undercooled metal particles, differences in modulus and processing temperatures can be overcome. Adoption of autonomous processes such as self-filtration, capillary pressure, and evaporative concentration leads to enhanced packing, stabilization (jamming) and point sintering with phase change to create solid metal replicas of complex bio-based features. Differentiation of subtle differences between cultivars of the rose flower with reproduction over large areas shows that this biomimetic metal patterning (BIOMAP) is a versatile method to replicate biological features either as positive or negative reliefs irrespective of the substrate. Using rose petal patterns, we illustrate the versatility of bio-templated mapping with undercooled metal particles at ambient conditions, and with unprecedented efficiency for metal structures. 相似文献
48.
The reaction of the aryne complex (PEt3)2Ni(eta2-C6H2-4,5-F2) with a catalytic amount of Ni(PEt3)2 results in a dinuclear Ni(I) complex from the coupling of the isomer (PEt3)2Ni(eta2-C6H2-3,4-F2), obtained via rearrangement of the aromatic C-H bonds, which demonstrates that Ni(PEt3)2 is kinetically capable of C-H bond activation, even in the presence of C-F bonds. The intermediate [(PEt3)2Ni]2(mu-eta2:eta2-C6H2-4,5-F2) was isolated and crystallographically characterized; the mu-eta2:eta2-bonding mode observed is unprecedented in aryne chemistry. 相似文献
49.
Duda TF Collis JM Lin YT Newhall AE Lynch JF DeFerrari HA 《The Journal of the Acoustical Society of America》2012,131(2):1782-1797
Sound at 85 to 450 Hz propagating in approximately 80-m depth water from fixed sources to a joint horizontal/vertical line array (HLA/VLA) is analyzed. The data are from a continental shelf area east of Delaware Bay (USA) populated with tidally generated long- and short-wavelength internal waves. Sound paths are 19 km in the along-shore (along internal-wave crest) direction and 30 km in the cross-shore direction. Spatial statistics of HLA arrivals are computed as functions of beam steering angle and time. These include array gain, horizontally lagged spatial correlation function, and coherent beam power. These quantities vary widely in magnitude, and vary over a broad range of time scales. For example, correlation scale can change rapidly from forty to five wavelengths, and correlation-scale behavior is anisotropic. In addition, the vertical array can be used to predict correlation expected for adiabatic propagation with cylindrical symmetry, forming a benchmark. Observed variations are in concert with internal-wave activity. Temporal variations of three coherence measures, horizontal correlation length, array gain, and ratio of actual correlation length to predicted adiabatic-mode correlation length, are very strong, varying by almost a factor of ten as internal waves pass. 相似文献
50.
Rafael Conceição Simões Bruno Anderson Matias Rocha Maria Julia Barbosa Bezerra Ito Liberato Barroso‐Neto Francisco Nascimento Pereira‐Junior Raniere da Mata Moura Kyria Santiago do Nascimento Celso Shiniti Nagano Plinio Delatorre Alana de Freitas Pires Ana Maria Sampaio Assreuy Alexandre Holanda Sampaio Benildo Sousa Cavada 《Rapid communications in mass spectrometry : RCM》2012,26(7):811-818