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991.
Suzana Bissacot Barbosa Silvia Rodrigues Machado Marcelo Pinto Marcelli 《Micron (Oxford, England : 1993)》2009,40(5-6):536-542
(Thallus structure and isidium development in two Parmeliaceae species (lichenized Ascomycota)). Conventional techniques for structural studies under light microscope and scanning electron microscope were employed to describe and compare the histology of thallus and isidia development in Parmotrema tinctorum and Parmelinopsis minarum. Although presenting layers typical of the heteromerous structure of Parmeliaceae lichens, the studied species have very distinct anatomical details including: the type of upper cortex, medulla thickness, hyphal orientation pattern and distinct strata in this layer, variations of crystal shape, color, location and degree of association with medullary hyphae, rhizines thickness and covering by a cortical layer. Isidium formation starts with cortical cell proliferation, which results in a small protuberance on the thallus surface, followed by the photobiont cell proliferation. Medullary hyphal intrusions occur only after the formation of this protuberance. In this stage medullary hyphae grow, ramifying or not inside the protuberance. In a posterior stage, the isidium base becomes constricted, which facilitates its detachment from the thallus. 相似文献
992.
Luis Simn FranciscoM. Muiz Silvia Sez Csar Raposo Francisca Sanz JoaquínR. Morn 《Helvetica chimica acta》2005,88(7):1682-1701
Different xanthone‐based receptors ( 2 – 10 ) for lactones and lactams have been prepared, and the feasibility of these compounds to mimic the known enzymatic ‘oxyanion‐hole’ structure is discussed. The self‐association of the receptors was found to pose a serious drawback for complex formation. X‐Ray crystal structures of receptor dimers allowed us to understand the reasons for their self‐association and to improve the design of the catalysts. The catalytic activity of the receptors has been tested towards the nucleophilic addition of pyrrolidine to unsaturated lactones. Since the resulting complexes were very weak in organic solvents, new receptors were developed for lactams, which showed better stabilities, and their catalytic activities were studied. 相似文献
993.
Giulia Bragaggia Andrea Cacciatore Elisa Poffe Claudia Capone Federico Zorzi Valerio Causin Silvia Gross 《Molecules (Basel, Switzerland)》2021,26(15)
Thermochromic dynamic cool materials present a reversible change of their properties wherein by increasing the temperature, the reflectance, conductivity, and transmittance change due to a reversible crystalline phase transition. In particular, vanadium (IV) dioxide shows a reversible phase transition, accompanied by a change in optical properties, from monoclinic VO2(M1) to tetragonal VO2(R). In this paper, we report on a systematic exploration of the parameters for the synthesis of vanadium dioxide VO2(M1) via an easy, sustainable, reproducible, fast, scalable, and low-cost hydrothermal route without hazardous chemicals, followed by an annealing treatment. The metastable phase VO2(B), obtained via a hydrothermal route, was converted into the stable VO2(M1), which shows a metal–insulator transition (MIT) at 68 °C that is useful for different applications, from energy-efficient smart windows to dynamic concrete. Within this scenario, a further functionalization of the oxide nanostructures with tetraethyl orthosilicate (TEOS), characterized by an extreme alkaline environment, was carried out to ensure compatibility with the concrete matrix. Structural properties of the synthesized vanadium dioxides were investigated using temperature-dependent X-ray Diffraction analysis (XRD), while compositional and morphological properties were assessed using Scanning Electron Microscopy, Energy Dispersive X-ray Analysis (SEM-EDX), and Transmission Electron Microscopy (TEM). Differential Scanning Calorimetry (DSC) analysis was used to investigate the thermal behavior. 相似文献
994.
Gianluigi Broggini Simona Galli Micol Rigamonti Silvia Sottocornola Gaetano Zecchi 《Tetrahedron letters》2009,50(13):1447-5771
Allenylamides of Boc-protected α-aminoacids easily gave in basic medium heterocyclic products arising from attack of the NH group on the inside C-C double bond of the 1,2-diene moiety, namely imidazolidinones, pyrazinones, and a pyrrole compound. The microwave-assisted heterocyclization occurred cleanly at C-β of the allenyl group with formation of pyrazin-2-ones having an endo- or exocyclic double bond. 相似文献
995.
The 3051 USEPA method (or alternatively, the 3051A) can be considered nowadays as a reference method to extract metals from sediments. However, after microwave heating, the sample must be allowed to cool down, which results in a considerable lengthening of the whole analytical process. Microwave ovens and their maintenance are, in addition, expensive, and its use is relatively dangerous. The use of ultrasound focused energy to assist the extraction of chemicals from solid samples is a safe and relatively cheap technique. In this work we propose a new method to extract simultaneously several elements from sediments using ultrasound energy focused in a glass probe to accelerate the process, and check its possibilities to become an alternative to the EPA3051(A) approach. The optimised procedure allows extracting 13 elements in only 6 min, with similar recoveries and, in general, better repetitivities than the EPA3051. In addition, the suspension is only slightly heated during the leaching process. 相似文献
996.
Rafael Gozalbes Silvia Mosulén Rodrigo J. Carbajo Antonio Pineda-Lucena 《Journal of computer-aided molecular design》2009,23(8):555-569
A combined strategy based on the development of pharmacophore hypotheses and NMR approaches is reported for the identification
of novel inhibitors of heparanase, a key enzyme involved in tumor metastasis through the remodeling of the subepithelial and
subendothelial basement membranes, resulting in the dissemination of metastatic cancer cells. Several pharmacophore hypotheses
were initially developed from the most active heparanase inhibitors known to date and, after their application to a pool of
27 known heparanase inhibitors and a database of 1,120 compounds approved by the FDA, a four-point pharmacophore model was
selected as the most predictive. This model was subsequently applied to a database of 686 chemical fragments, and a subset
of 100 fragments accomplishing completely or partially the four-point model was selected to perform nuclear magnetic resonance
experiments to validate the hypothesis. The experimental studies confirmed the reliability of our pharmacophore model, its
applicability to in silico databases in order to reduce the number of compounds to be experimentally screened, and the possibility
of generating fragment libraries enriched in heparanase inhibitors.
Rafael Gozalbes and Silvia Mosulén contributed equally to this work. 相似文献
997.
Urska Lavrencic Stangar Alessandro Sassi Alfonso Venzo Andrea Zattin Boštjan Japelj Boris Orel Silvia Gross 《Journal of Sol-Gel Science and Technology》2009,49(3):329-335
The sol–gel reactions of the two methacrylate-modified silanes methacryloxymethyltriethoxysilane (MAMTES) and methacryloxypropyltrimethoxysilane
(MAPTMS) were followed by using two independent time-resolved spectroscopic methods, viz., IR ATR and NMR with the aim to
optimise their pre-hydrolysis times and consequently their use as precursors for hybrid materials. Time resolved measurements
were carried out on the two systems under sol–gel conditions. Whereas the hydrolysis of both siloxanes is very fast, condensation
proceeds gradually and is not completely finished within 5 h. 相似文献
998.
Nicola Marchi Qingshan Teng Minh T Nguyen Linda Franic Nirav K Desai Thomas Masaryk Peter Rasmussen Silvia Trasciatti Damir Janigro 《BMC neuroscience》2010,11(1):34
Background
Stem cells or immune cells targeting the central nervous system (CNS) bear significant promises for patients affected by CNS disorders. Brain or spinal cord delivery of therapeutic cells is limited by the blood-brain barrier (BBB) which remains one of the recognized rate-limiting steps. Osmotic BBB disruption (BBBD) has been shown to improve small molecule chemotherapy for brain tumors, but successful delivery of cells in conjunction with BBBD has never been reported. 相似文献999.
Leandro Javier Salvo Lorenzo Coiana Cecilia Dobrecky Valeria Tripodi Sabrina Flor Silvia Lucangioli 《Electrophoresis》2019,40(12-13):1719-1721
A simple and highly sensitive CE–UV method was applied in the determination of l ‐ctrulline, which was developed from an oral formulation for pediatric use. The novel method was based on the analysis of l ‐citrulline for direct ultraviolet detection at 198 nm. The BGE consisted of 10 mM sodium tetraborate and 50 mM SDS at pH 9, and the electrophoretic parameters were optimized. The method was validated in terms of specificity, linearity, LOD, LOQ, precision, accuracy, and robustness. The LOD and LOQ obtained were 1.36 and 4.54 μg/mL, respectively. In addition, the method offers higher sensitivity and specificity compared with the results obtained from HPLC method using UV‐detectors, in which l‐ citrulline needs to be derivatizated. Furthermore, low cost and simplicity of the system allowed the rapid and simple quantitation of l‐ citrulline in the oral formulation for quality control and stability indicated method. 相似文献
1000.