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81.
Lilian S. Schaffroth Jakob Lenz Veit Giegold Maximilian Kgl Achim Hartschuh R. Thomas Weitz 《Advanced materials (Deerfield Beach, Fla.)》2019,31(16)
Determining the electronic properties of nanoscopic, low‐dimensional materials free of external influences is key to the discovery and understanding of new physical phenomena. An example is the suspension of graphene, which has allowed access to their intrinsic charge transport properties. Furthermore, suspending thin films enables their application as membranes, sensors, or resonators, as has been explored extensively. While the suspension of covalently bound, electronically active thin films is well established, semiconducting thin films composed of functional molecules only held together by van der Waals interactions could only be studied supported by a substrate. In the present work, it is shown that by utilizing a surface‐crystallization method, electron conductive films with thicknesses of down to 6 nm and planar chiral optical activity can be freely suspended across several hundreds of nanometers. The suspended membranes exhibit a Young's modulus of 2–13 GPa and are electronically decoupled from the environment, as established by temperature‐dependent field‐effect transistor measurements. 相似文献
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84.
Lilian Anne Krug Douglas Francisco Marcolino Gherardi José Luiz Stech Zelinda Margarida De Andrade Nery Leão Ruy Kenji Papa De Kikuchi 《International journal of remote sensing》2013,34(13):4059-4074
The relation between climate variability and coral bleaching in the Bahia reefs was investigated in an attempt to characterize the bleaching environments. The following 13-year time series were derived from the remote-sensing, analysis and reanalysis data: maximum summertime sea surface temperature (SST), maximum sea surface temperature (MaxSST) accumulated in 5 days (SSTAc5day), diffuse attenuation coefficient for downward irradiance at 490 nm (K 490), rainfall and magnitude of surface wind fields, including the zonal (U) and meridional components. Principal component analysis, non-metric multidimensional scaling (MDS) and cluster and similarity analyses indicate the complex nature of the bleaching patterns and the influence of the strong 1997–1998 El Niño. A significant (global R-value?=?0.65; p < 0.01) compounding effect of the reef location and bleaching intensity on the differentiation of bleaching environments was detected. A combination of high SSTAc5day and low K 490 may cause coral bleaching in the northernmost reefs. Evidence clearly points to a scenario where the influence of reef location, bleaching year and intensity may produce a compounded effect that determines the bleaching environments in Bahia. 相似文献
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86.
Jefferson Rodrigues de Souza Lilian da Silva Márcia Silva da Rocha Tatiana Dillenburg Saint’Pierre 《Food Analytical Methods》2017,10(9):3088-3097
The aim of this work was to evaluate different approaches employing a reaction cell to circumvent spectral interferences over 80Se+ to increase the sensitivity in the determination of Se by inductively coupled plasma mass spectrometry (ICP-MS). Different gases (NH3, CH4, and O2) were employed, and the operating conditions were optimized by a central composite design, evaluating the effect of the reaction gas flow rate and the rejection parameter q (Rpq) on the limit of detection (LOD) of the method. All reaction gases studied reduced the interference by 40Ar2 + over 80Se+, reducing the LOD when compared to the LOD obtained with ICP-MS operating in the standard mode (LOD = 0.2 μg kg?1). A better LOD (0.01 μg kg?1) was obtained with CH4, while 0.1 μg kg?1 was the LOD with NH3. The use of O2 as a reaction gas enabled the determination of Se at m/z 96 (80Se16O+) with adequate analytical performance (LOD = 0.03 μg kg?1). The accuracy of the method was evaluated by analyzing the certified reference material (CRM) Selm-1, and the results obtained ranged from 99 to 104% of the certified value. In addition, Se dietary supplements of four different brands and commercial yeast were analyzed, and the major sources of uncertainty were studied. The dietary supplements followed the criteria adopted by Brazilian legislation, although the uncertainty study highlighted the great variation in the Se content of each brand. Clearly, the manufacturing process of dietary supplements needs more rigorous quality control, considering that this product can affect the health of consumers. 相似文献
87.
Nancy Robledo Luis López Andrea Bunger Cristian Tapia Lilian Abugoch 《Food and Bioprocess Technology》2018,11(8):1566-1574
The effectiveness of the edible coating with thymol nanoemulsion on the safety, sensorial properties, and quality of refrigerated strawberries was investigated under commercial storage conditions. Spontaneous emulsification was used to obtain the thymol nanoemulsion that was included on quinoa protein/chitosan coatings. During the entire storage time, strawberries coated with thymol-antimicrobial packaging had a lower fungal and yeast load compared with the controls (uncoated and coated with quinoa protein/chitosan). The flavour and aroma of the coated strawberries was initially affected, although this sensory appreciation was improved from the fifth day of storage and showed similar scores than the controls, and presenting better aroma score at day 12 of storage. Furthermore, the shelf life of the thymol nanoemulsion-coated strawberries increased in 4 days, unlike that in the both controls. Further, the application of these biocoatings on strawberries significantly decreased the weight loss relative to that in the control, during 16 days of storage at 5 °C and 90% relative humidity, and did not alter the quality parameters (pH, titrable acidity, and percentage of soluble solids). These results suggest that the application of thymol/nanomulsion-loaded edible films is an effective strategy to increase the shelf life of highly perishable products such as strawberries. 相似文献
88.
Two series of arborescent polystyrenes were prepared by successive cycles of functionalization and anionic grafting reactions. A target branching functionality of around 15 side chains per backbone chain and a constant branch molecular weight of either 5000 g mol−1 (S05 series) or 30 000 g mol−1 (S30 series) were used for each generation. The intrinsic viscosity of each polymer series was relatively insensitive to molecular weight, a behaviour typical of hard spheres. The S30 polymers expanded considerably in toluene relative to cyclohexane, but the S05 polymers were unaffected by change in solvent quality. Analysis by d.s.c. showed that limiting Tg values are reached in the upper generations of each polymer series, similarly to polymer networks prepared from primary chains with a low molecular weight. A lower ΔCp and a broader transition range observed for the upper generation S05 polymers may be related to a decrease in chain mobility inside the molecules. No similar effects were observed in the S30 polymers. © 1997 Elsevier Science Ltd. 相似文献
89.
We have evaluated the effect of filgrastim on proliferation and differentiation activity of granulopoietic cells in mice pretreated with methotrexate. Filgrastim was injected daily, from day 8 to 28 after cytotoxic agent administration. The granulopoiesis changes were measured by assessment of GM-CFU cells content, marrow and spleen granuloid cells pool as well as circulating neutrophils. In MTX pretreated mice, bone marrow GM-CFU oscillating values were higher than normal values, but these changes were not followed by high proliferative activity in granuloid precursor cell compartment. After MTX treatment, filgrastim administration was unable to stimulate marrow granulopoiesis as observed in normal mice. In the spleen, MTX led to dramatic changes in the proliferative activity of GM-CFU cells, but did not result in spleen granuloid cell changes. However, filgrastim treatment induced a spleen granuloid amplification, similar to the changes observed in circulating neutrophils values. We suggest that these findings can be explained by inhibition of differentiation of marrow GM-CFU cells into the more mature granulopoietic cells and/or by an inhibited proliferative activity of marrow granuloid cells. They can be also explained in terms of an unfavorable marrow microenvironment for granulopoiesis, contrary to a supportive spleen microenvironment. 相似文献
90.
玉米须提取物对食品腐败菌及致病菌抑制作用的研究 总被引:18,自引:1,他引:17
首次以玉米须提取物对七种常见的食品腐败菌及致病菌进行抑菌试验,发现玉米须的乙醇提取物的效果最好,其最低抑菌浓度(MIC)为3.0g/100g。此外,对食品加工条件(如杀菌方式等)及食品介质(如pH)对玉米须提取物抑菌活性的影响也作了研究。结果表明。玉米须提取物在常规食品杀菌条件(UHT)及中酸到酸性环境下抑菌活性稳定,因而可做为潜在的食品防腐剂。 相似文献