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排序方式: 共有1143条查询结果,搜索用时 31 毫秒
71.
Maria Michela Salvatore Ilaria Di Lelio Marina DellaGreca Rosario Nicoletti Francesco Salvatore Elia Russo Gennaro Volpe Andrea Becchimanzi Alla Eddine Mahamedi Akila Berraf-Tebbal Anna Andolfi 《Molecules (Basel, Switzerland)》2022,27(7)
An undescribed 5,6-dihydropyran-2-one, namely diplopyrone C, was isolated and characterized from the cultures of an isolate of the fungus Diplodia corticola recovered from Quercus suber in Algeria. The structure and relative stereostructure of (5S,6S,7Z,9S,10S)-5-hydroxy-6-(2-(3-methyloxiran-2-yl)vinyl)-5,6-dihydro-2H-pyran-2-one were assigned essentially based on NMR and MS data. Furthermore, ten known compounds were isolated and identified in the same cultures. The most abundant product, the tetracyclic pimarane diterpene sphaeropsidin A, was tested for insecticidal effects against the model sucking aphid, Acyrthosiphon pisum. Results showed a toxic dose-dependent oral activity of sphaeropsidin A, with an LC50 of 9.64 mM. 相似文献
72.
Rodríguez Patino JM Molina Ortiz SE Carrera Sánchez C Rodríguez Niño MR Añón MC 《Journal of colloid and interface science》2003,268(1):50-57
In this paper we present surface dilatational properties of soy globulins (beta-conglycinin, glycinin, and reduced glycinin with 10 mM of dithiothreitol (DTT)) adsorbed onto the air-water interface, as a function of adsorption time. The experiments were performed at constant temperature (20 degrees C), pH (8.0), and ionic strength (0.05 M). The surface rheological parameters were measured as a function of protein concentration (ranging from 1 to 1x10(-3)% wt/wt). We found that the surface dilatational modulus, E, increases, and the phase angle, phi, decreases with time, theta, which may be associated with protein adsorption. These phenomena have been related to protein adsorption, unfolding, and/or protein-protein interactions (at long-term adsorption) as a function of protein concentration in solution. From a rheological point of view, the surface viscoelastic characteristics of soy globulin films adsorbed at the air-water interface are practically elastic. The main conclusion is that the dilatational properties of the adsorbed films depend on the molecular structure of the protein. 相似文献
73.
Jazer Jose H. Togonon Eugene A. Esparcia Jr. Prof. Julie Anne D. del Rosario Prof. Joey D. Ocon 《ChemistryOpen》2021,10(4):471-476
Biodegradable primary batteries, also known as transient batteries, are essential to realize autonomous biodegradable electronic devices with high performance and advanced functionality. In this work, magnesium, copper, iron, and zinc – metals that exist as trace elements in the human body – were tested as materials for biomedical transient electronic devices. Different full cell combinations of Mg and X (where X = Cu, Fe, and Zn and the anodized form of the metals) with phosphate buffered saline (PBS) as electrolyte were studied. To form the cathodes, metal foils were anodized galvanostatically at a current density of 2.0 mA cm−2 for 30 mins. Electrochemical measurements were then conducted for each electrode combination to evaluate full cell battery performance. Results showed that the Mg−Cuanodized chemistry has the highest power density at 0.99 mW/cm2. Nominal operating voltages of 1.26 V for the first 0.50 h and 0.63 V for the next 3.7 h were observed for Mg−Cuanodized which was discharged at a current density of 0.70 mA cm−2. Among the materials tested, Mg−Cuanodized exhibited the best discharge performance with an average specific capacity of 2.94 mAh cm−2, which is comparable to previous reports on transient batteries. 相似文献
74.
Stephen L. Howard Joyce E. Newberry Rosario C. Sausa Andrzej W. Miziolek 《Journal of the American Society for Mass Spectrometry》1993,4(2):152-158
A recently developed research apparatus for characterization of low-pressure premixed flames has been developed and was used to characterize the C2H4/N2O/Ar flame at 20 torr. This instrument incorporates several diagnostic techniques in one apparatus so that individual techniques can be quantitatively compared and the usable detection range (both in terms of resolution and species detection) expanded. Results discussed in this report include mass analysis by triple quadrupole mass spectrometer and temperature measurement by thermocouple. Concentration profiles in the one-dimensional flame include CO, N2, and C2H4, at nominal m/z 28 as well as CO2 and N2O at m/z 44. 相似文献
75.
Eduardo Rosado Paloma Delgado-Fernndez Blanca de las Rivas Rosario Muoz Francisco Javier Moreno Nieves Corzo Cesar Mateo 《Molecules (Basel, Switzerland)》2022,27(4)
The synthesis of β-galactosyl xylitol derivatives using immobilized LacA β-galactosidase from Lactobacillus plantarum WCFS1 is presented. These compounds have the potential to replace traditional sugars by their properties as sweetener and taking the advantages of a low digestibility. The enzyme was immobilized on different supports, obtaining immobilized preparations with different activity and stability. The immobilization on agarose-IDA-Zn-CHO in the presence of galactose allowed for the conserving of 78% of the offered activity. This preparation was 3.8 times more stable than soluble. Since the enzyme has polyhistidine tags, this support allowed the immobilization, purification and stabilization in one step. The immobilized preparation was used in synthesis obtaining two main products and a total of around 68 g/L of β-galactosyl xylitol derivatives and improving the synthesis/hydrolysis ratio by around 30% compared to that of the soluble enzyme. The catalyst was recycled 10 times, preserving an activity higher than 50%. The in vitro intestinal digestibility of the main β-galactosyl xylitol derivatives was lower than that of lactose, being around 6 and 15% for the galacto-xylitol derivatives compared to 55% of lactose after 120 min of digestion. The optimal amount immobilized constitutes a very useful tool to synthetize β-galactosyl xylitol derivatives since it can be used as a catalyst with high yield and being recycled for at least 10 more cycles. 相似文献
76.
77.
Kobra Mahdavipour Mahshid Khazaei Shadfar Hossein Rangani Jahromi Roberto Morandotti Rosario Lo Franco 《Entropy (Basel, Switzerland)》2022,24(3)
A witness of non-Markovianity based on the Hilbert–Schmidt speed (HSS), a special type of quantum statistical speed, has been recently introduced for low-dimensional quantum systems. Such a non-Markovianity witness is particularly useful, being easily computable since no diagonalization of the system density matrix is required. We investigate the sensitivity of this HSS-based witness to detect non-Markovianity in various high-dimensional and multipartite open quantum systems with finite Hilbert spaces. We find that the time behaviors of the HSS-based witness are always in agreement with those of quantum negativity or quantum correlation measure. These results show that the HSS-based witness is a faithful identifier of the memory effects appearing in the quantum evolution of a high-dimensional system with a finite Hilbert space. 相似文献
78.
Nikolay Djourelov Corine Bas Daniel Sillou Rosario Benavente Ernesto Pérez María L. Cerrada 《Journal of Polymer Science.Polymer Physics》2010,48(18):1994-2002
Copolymers of propylene and 1‐octadecene synthesized by a metallocene catalyst were characterized by PALS, WAXD, DSC, and density measurements. The change in the sizes and the number density of free‐volume holes as a function of the 1‐octadecene content were compared to the master laws published for copolymers of propylene with α‐olefins of shorter lengths. It was found that the samples were separated into two groups. The first set of samples obeyed the master laws while the second group deviated. This behavior was explained by the difference in the copolymer structure. The WAXD analysis confirmed the separation as well. The deviation was explained as due to the mesomorphic crystalline structure of the second group of samples, in contrast to the monoclinic one for the first group, which was a result of the relatively fast cooling from the molten state and from the high comonomer molar content. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1994–2002, 2010 相似文献
79.
Alcohol‐Induced C−N Bond Cleavage of Cyclometalated N‐Heterocyclic Carbene Ligands with a Methylene‐Linked Pendant Imidazolium Ring
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Dr. Wei Zhong Dr. Zhaofu Fei Dr. Rosario Scopelliti Prof. Dr. Paul J. Dyson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(34):12138-12144
Reaction of the pentamethylcyclopentadienyl rhodium iodide dimer [Cp*RhI2]2 with 1,1′‐diphenyl‐3,3′‐methylenediimidazolium diiodide in non‐alcohol solvents, in the presence of base, led to the formation of bis‐carbene complex [Cp*Rh(bis‐NHC)I]I (bis‐NHC=1,1′‐diphenyl‐4,4′‐methylenediimidazoline‐5,5′‐diylidene). In contrast, when employing alcohols as the solvent in the same reaction, cleavage of a methylene C?N bond is observed, affording ether‐functionalized (cyclometalated) carbene ligands coordinated to the metal center and the concomitant formation of complexes with a coordinated imidazole ligand. Studies employing other 1,1′‐diimidazolium salts indicate that the cyclometalation step is a prerequisite for the activation/scission of the C?N bond and, based on additional experimental data, a SN2 mechanism for the reaction is tentatively proposed. 相似文献
80.
Nirupama Singh Surbhi Choudhary Sumant Upadhyay Vibha R. Satsangi Sahab Dass Rohit Shrivastav 《Journal of Solid State Electrochemistry》2014,18(2):523-533
Nanocrystalline Zn1???x Ag x O y (x?=?10??3???50?×?10??3) thin films evolved through electrodeposition over ITO substrate have been investigated for photoelectrochemical splitting of water. Samples were characterized by XRD, EDX, SEM, AFM, UV–visible optical absorption, and Mössbauer spectral analysis. Ag incorporation led to a decrease in the band gap energy and alterations in microstructural and semiconductor properties. Raising Ag concentration in samples up to 1 % at. caused a significant reduction in density and electrical resistivity, enhanced absorption along with red shift to the band gap energy, anodic shift in flat band potential, and increased charge carrier density, enabling 1 % at. Ag-incorporated ZnO films most photosensitive by yielding highest short-circuit current, photocurrent density, and applied bias photon to current efficiency. Plausible reasons have been offered. 相似文献