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51.
Hydrophobic‐Force‐Driven Removal of Organic Compounds from Water by Reduced Graphene Oxides Generated in Agarose Hydrogels
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Chongling Cheng Dr. Yongqing Cai Dr. Guijian Guan Prof. Leslie Yeo Prof. Dayang Wang 《Angewandte Chemie (International ed. in English)》2018,57(35):11177-11181
Hydrophobic reduced graphene oxides (rGOs) were generated in agarose hydrogel beads (AgarBs) by NaBH4 reduction of graphene oxides (GOs) initially loaded in the AgarBs. The resulting rGO‐loaded AgarBs were able to effectively adsorb organic compounds in water as a result of the attractive hydrophobic force between the rGOs in the AgarBs and the organic compounds dissolved in aqueous media. The adsorption capacity of the rGOs was fairly high even toward reasonably water‐soluble organic compounds such as rhodamine B (321.7 mg g?1) and aspirin (196.4 mg g?1). Yet they exhibited salinity‐enhanced adsorption capacity and preferential adsorption of organic compounds with lower solubility in water. Such peculiar adsorption behavior highlights the exciting possibility for adopting an adsorption strategy, driven by hydrophobic forces, in practical wastewater treatment processes. 相似文献
52.
Dr. Qingqing Miao Dr. David C. Yeo Dr. Christian Wiraja Dr. Jianjian Zhang Xiaoyu Ning Prof. Chenjie Xu Prof. Kanyi Pu 《Angewandte Chemie (International ed. in English)》2018,57(5):1256-1260
Early detection of skin diseases is imperative for their effective treatment. However, fluorescence molecular probes that allow this are rare. The first activatable near‐infrared (NIR) fluorescent molecular probe is reported for sensitive imaging of keloid cells, skin cells from abnormal scar fibrous lesions. As keloid cells have high expression levels of fibroblast activation protein‐alpha (FAPα), the probe (FNP1) is designed to have a caged NIR dye and a FAPα‐cleavable peptide substrate linked by a self‐immolative segment. FNP1 can quickly and specifically turn on its fluorescence at 710 nm by 45‐fold in the presence of FAPα, allowing it to effectively recognize keloid cells from normal skin cells. Integration of FNP1 with a simple microneedle‐assisted topical application enables sensitive detection of keloid cells in metabolically‐active human skin tissue with a theoretical limit of detection down to 20 000 cells. 相似文献
53.
Towards chemical analysis of nanostructures in biofilms II: tip-enhanced Raman spectroscopy of alginates 总被引:1,自引:1,他引:0
Schmid T Messmer A Yeo BS Zhang W Zenobi R 《Analytical and bioanalytical chemistry》2008,391(5):1907-1916
This study examines the feasibility of using tip-enhanced Raman spectroscopy (TERS) for label-free chemical characterization
of nanostructures in biological systems. For this purpose, a well-defined model system consisting of calcium alginate fibers
is studied. In a companion paper, calcium alginate fibers and their network structures were shown to be a good model for the
extracellular polysaccharides of biofilms at the nanoscale. TERS analysis of biological macromolecules, such as alginates,
is complicated by heterogeneity in their sequence, molecular weight, and conformations, their small Raman cross-section, and
the large number of functional groups, which can chemically interact with the silver surface of the tip and cause significant
band shifts. Due to these effects, Raman frequencies in TERS spectra of biopolymers do not necessarily resemble band positions
in the normal Raman spectrum of the bulk material, as is the case for less complex samples (e.g., dye molecules) studied so
far. Additionally, analyte decomposition due to laser heating can have a significant influence, and carbon contamination signals
can sometimes even overwhelm the weak analyte signals. Based on the investigation of alginates, strategies for spectra correction,
choice of appropriate reference samples, and data interpretation are presented. With this approach, characteristic frequency
ranges and specific marker bands can be found for biological macromolecules that can be employed for their identification
in complex environments.
Figure TERS spectrum of a calcium alginate fiber bundle 相似文献
54.
Schmid T Burkhard J Yeo BS Zhang W Zenobi R 《Analytical and bioanalytical chemistry》2008,391(5):1899-1905
Due to their direct influence on the stability of bacterial biofilms, a better insight into the nanoscopic spatial arrangement
of the different extracellular polymeric substances (EPS), e.g., polysaccharides and proteins, is important for the improvement
of biocides and for process optimization in wastewater treatment and biofiltration. Here, the first application of a combination
of confocal laser-scanning microscopy (CLSM) and atomic force microscopy (AFM) to the investigation of river-water biofilms
and related biopolymers is presented. AFM images collected at selected areas of CLS micrographs dramatically demonstrate the
heterogeneity of biofilms at the nanometer scale and the need for a chemical imaging method with nanoscale resolution. The
nanostructures (e.g., pili, flagella, hydrocolloids, and EPS) found in the extracellular matrix are classified according to
shape and size, which is typically 50–150 nm in width and 1–10 nm in thickness, and sets the demands regarding spatial resolution
of a potential chemical imaging method. Additionally, thin layers of the polysaccharide alginate were investigated. We demonstrate
that calcium alginate is a good model for the EPS architecture at the nanometer scale, because of its similar network-like
structure.
Figure CLSM-AFM allows imaging of nanometer-sized extracellular structures 相似文献
55.
Min Yeo K Ji Gao C Ahn KH Su Lee I 《Chemical communications (Cambridge, England)》2008,(38):4622-4624
The incorporation of superparamagnetic iron oxide nanoparticles with sulfur-oxidized diarylethene molecules resulted in a novel multifunctional nanosystem, in which the fluorescent performance and flocculation and dispersion are reversibly switched by light irradiation and external magnetic field, respectively. 相似文献
56.
57.
From the ethyl acetate fraction of the roots of Ostericum koreanum, a new chromone, 11-hydroxy-sec-O-glucosylhamaudol (1) along with the known compounds: four chromones, three coumarins, six phenolic compounds, and three quinic acids were isolated. These compounds were assessed for antioxidant activities in the DPPH radical and superoxide anion radical scavenging assay systems. Among isolates, 4-(2-hydroxy-vinyl)-benzene-1,2-diol (12) showed the most potent DPPH radical scavenging activity (IC(50)=4.80+/-0.62 mug/ml) and superoxide anion radical scavenging activity (IC(50)=11.05+/-0.83 microg/ml) in the xanthine/xanthine oxidase system. The antioxidant activities of 12 were comparable to those of quercetin and luteolin. 相似文献
58.
Jae Cheol Cho Keon Hyeong Kim Kwang Ung Kim Soonjong Kwak Jungahn Kim Won Ho Jo Moon Seok Chun Chan Hong Lee Jong Ki Yeo Roderic P. Quirk 《Journal of polymer science. Part A, Polymer chemistry》1998,36(11):1743-1753
The most important variable affecting the yield in the coupling reactions of polymeric organolithium compounds with chlorosilane compounds has been investigated through size-exclusion chromatographic (SEC) analysis. The coupling reaction of poly(styryl)lithium with dichlorodimethylsilane as a silane-coupling agent provided 44 wt % of the coupling yield. The coupling yield, depending on the chain end reactivity of active polymers, was not greatly affected. The addition of a Lewis base such as N,N,N′,N′-tetramethylethylenediamine (TMEDA) even after complete polymerization of the dienes in hydrocarbon seems to affect the coupling reaction, resulting in decreasing the yield. The 1,2- or 3,4-enchain contents in the polydiene backbones affected the reduction of the linking efficiency in the coupling of the poly(dienyl)lithiums with chlorosilanes as the linking agent. The linking yields of the active polymers including over 75 mol % of 1,2- or 3,4-enchainment on the polydiene segment were below 20 wt %. The linking yields exhibited a dependence not only on the steric requirement of the chain end, but also the microstructure of the polydiene segment. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1743–1753, 1998 相似文献
59.
Anders Yeo 《Journal of Graph Theory》1999,32(2):123-136
The local irregularity of a digraph D is defined as il(D) = max {|d+ (x) − d− (x)| : x ϵ V(D)}. Let T be a tournament, let Γ = {V1, V2, …, Vc} be a partition of V(T) such that |V1| ≥ |V2| ≥ … ≥ |Vc|, and let D be the multipartite tournament obtained by deleting all the arcs with both end points in the same set in Γ. We prove that, if |V(T)| ≥ max{2il(T) + 2|V1| + 2|V2| − 2, il(T) + 3|V1| − 1}, then D is Hamiltonian. Furthermore, if T is regular (i.e., il(T) = 0), then we state slightly better lower bounds for |V(T)| such that we still can guarantee that D is Hamiltonian. Finally, we show that our results are best possible. © 1999 John Wiley & Sons, Inc. J Graph Theory 32: 123–136, 1999 相似文献
60.
A very simple model based on the three‐dimensional desingularized boundary integral method is applied to study the evolution of bubble(s) with or without the presence of solid structures. The choice of the desingularization parameters, which is crucial to the success of the method, is studied in the context of bubble dynamics. With the proper choice of parameters, the new model is far more efficient than previous models with virtually the same level of accuracy being achieved. This is largely attributed to the simplicity of the desingularization method. Furthermore, the new model offers a simple and attractive way for mesh refinement. Although it has limitations in the sense that, with this model the time stepping tends to slow down as two surfaces approach each other, this can be easily rectified by switching over to a direct method so that the two surfaces can be drawn closer as required in the context of jet impact. After this the new model can be reinstated to treat the complicated doubly connected geometry involving toroidal bubbles that would otherwise be very difficult to deal with. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献