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BackgroundCellulose nanocrystalline (CNC) particles possess unique functional properties such as vastly modifiable surface, considerable mechanical strength and acid resistance, as well as, high aspect ratio. CNCs have received great attention for application in diverse fields of technology including (composite) hydrogels fabrication for the gastric protection and enteral delivery of drugs and nutraceuticals.Scope and approachThe orogastrointestinal digestibility and absorbability of the orally administered CNCs is overviewed in the current article. At first, some surface charge-related characteristics of acid-isolated CNCs are communicated. Then, the biocompatibility and biodegradability of CNCs and CNC-reinforced hydrogels are reviewed, followed by presenting credible digestion and absorption scenarios. Finally, the post-absorption metabolism of CNCs is briefly debated.Key findings and conclusionsBacterial cellulose shows good biocompatibility and hemocompatibility. CNC oxidation provides biologically beneficial impacts; for instance, the TEMPO- and periodate-oxidized CNCs have been shown to regulate some blood metabolic variables and improve the degradability in simulated human blood plasma, respectively. Spherical and carboxyl-bearing cellulose nanoparticles can be isolated through ammonium persulfate digestion. The sphericity of particles results in faster cellular uptake. Negatively-charged CNCs are non-mucoadhesive and thus upon ingestion can penetrate into the buccal and intestinal mucosa. One may augment the absorption of CNCs by targeted receptor-mediated endocytosis. It was postulated that sodium bicarbonate secretion into the duodenum can alter CNCs surface chemistry and influence CNC interaction with gut microbiota. 相似文献
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《International Journal of Hydrogen Energy》2020,45(16):9635-9647
In this work, a cascade structure among ZnSe, carbon membrane and TiO2 NTAs was constructed precisely. This carbon membrane bridged ZnSe and TiO2 composite exhibits excellent H2 evolution activity, the H2 evolution rate of ZnSe/C/TiO2 NTAs (866.76 μmol/cm2) is about 6.95 times higher than that of pure TiO2 NTAs (124.64 μmol/cm2) after 200 min irradiation. The introduction of carbon membrane can greatly facilitate the electron transfer from ZnSe to TiO2, ZnSe/C/TiO2 ternary composite exhibits the highest transient photocurrent density (1.05 mA/cm2) and the lowest impedance (677.6 Ω) among all the samples. Besides, the contact between TiO2 and electrolyte is improved after introducing carbon membrane, therefore C/TiO2 NTAs shows more positive flat band potential of (1.86 V) compared with TiO2 NTAs (0.50 V). It is also found that pure carbon powder can achieve H2 production under visible light irradiation, its sensitization effect can further improve photocurrent density of the composite under 500 nm light radiation, the electrons produced in carbon film can inject into TiO2, and holes from TiO2 can quickly transfer to carbon film, leading to excellent H2 evolution efficiency. 相似文献
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II3V2 semiconductors have become increasingly popular for a variety of applications including solar light harvesting, near‐IR imaging, and low energy light detection. The bulk physical and electronic structure of these materials is highlighted, followed by an in‐depth survey on progress in synthesizing these semiconductors as colloidal nanocrystals. Interestingly, no universal synthetic approach has yet been developed to access all compounds within this family. A discussion on how the complex crystal structure of these materials translates to small domain sizes will highlight current challenges in the characterization of II3V2 nanocrystals. Finally, potential avenues for further research will be proposed as a way to advance this field towards greater utilization in light harvesting applications. 相似文献
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Jiasong Zhong Weidong Xiang Zhaoping Chen Haijun Zhao Xiaojuan Liang 《Materials Science and Engineering: B》2013,178(15):998-1003
Cu nanocrystals embedded in sodium borosilicate glass of varied Cu contents from 0.5 to 1.5 wt% have been successfully prepared through a sol–gel process. According to the results of X-ray diffraction (XRD) and the energy dispersive X-ray spectrometry (EDS), the metal Cu nanocrystals in cubic crystal system were well distributed inside glass matrix. Fourier Transform Infrared (FTIR) indicated the sodium borosilicate matrix had no major structural change for gels with different Cu contents. The optical absorption peaks due to the surface plasmon resonance of Cu particles were observed in the wavelength range of 550–600 nm. The absorption peak showed a red-shift trend with increasing Cu contents from 0.5 to 1.5 wt%. Transmission electron microscopy (TEM) revealed the existence of spherical Cu nanocrystals in the matrix. The diameter of Cu nanocrystals varied from 1 to 3.5 nm. Furthermore, the third-order nonlinear optical properties were investigated by Z-scan technique at 800 nm. Experimental results indicated the Cu nanocrystals have obvious positive refractive nonlinearities and reverse saturated absorption performance. 相似文献
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Nengbing Long Yanqing Fu Tianxiang Xu Dashuang Ding Shaoqian Zhang Shengzhi Sun Shiliang Kang Tiefeng Xu Shixun Dai Qiuhua Nie Changgui Lin 《Journal of the European Ceramic Society》2021,41(8):4584-4589
The confinement of CsPbX3 (X = Cl, Br, and I) perovskite nanocrystals (NCs) in a stabilized inorganic glass matrix is a new strategy for improving their long-term stability and promoting their applications in the optoelectronic field. Here, in situ nanocrystallization strategy is developed to precipitate CsPbBr3?xIx NCs with arbitrary I/Br ratio among an elaborately designed GeS2–Sb2S3-based chalcogenide glass matrix. Spherical CsPbBr3?xIx NCs are homogeneously distributed in the glass matrix after thermal treatment. The photoluminescence (PL) spectra show that the emission peaks of CsPbBr3?xIx NCs can be tuned from 570 nm to 722 nm with the replacement of Br by I. The fs transient absorption (TA) spectra reveal that there exists some structural defects in the NCs, leading to short PL decay life. This work would shed light on confining CsPbX3 NCs into glassy matrices, facilitating their future applications in photoelectronic fields. 相似文献
8.
《Ceramics International》2020,46(9):13331-13341
In this study, zirconia (ZrO2) and dysprosia-stabilized zirconia (DySZ) nanocrystals were synthesized using a chemical coprecipitation method. The crystal structure and micromorphology of the as-synthesized powders, as well as the structural evolution from precursors to oxides were investigated, and the synthesis mechanism was also examined. Results show that pure ZrO2 powders mainly comprise the monoclinic ZrO2 phase with trace tetragonal ZrO2, while the DySZ powders exhibit a tetragonal ZrO2 structure. In addition, the crystal growth rate of DySZ is far slower than that of the pure ZrO2 under elevated calcination temperature. The addition of Dy could significantly improve the phase stability of DySZ powder and effectively inhibit the crystal growth of DySZ. In the DySZ precursor, the binding energy of chemical bonds is significantly difference than in the ZrO2 precursor. A composite hydroxide can be formed with -Zr-OH-Dy- and -Zr-OH-Zr- units in the tetramer structure because of the in-situ substitution of Zr by Dy atoms. Both the ZrO2 and DySZ precursors exhibit analogous dehydration and crystallization behaviours in calcination process. Dy-doping plays a significant role in stabilizing both the intermediate product and the DySZ crystal. 相似文献
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Xu Changfu Ma Mo Zeng Songjun Ren Guozhong Yang Liwen Yang Qibin 《Journal of Alloys and Compounds》2011,509(30):7943-7947
A series of monodisperse ultrasmall Ba2YbF7 nanocrystals with intense upconversion emission were synthesized via a facile solvothermal method by using oleic acid as capping ligands. X-ray diffraction (XRD) and transmission electron microscopy (TEM) assays revealed that the as-synthesized Ba2YbF7 nanocrystals are of cubic structure, rather than the reported tetragonal structure. The cell parameter of the particles is 5.918 Å. The Er3+ or Tm3+ doped Ba2YbF7 nanocrystals with the size of sub-10 nm can give an intense upconversion emission under the 980 nm laser excitation and the upconversion processes were discussed. The Ba2YbF7 nanocrystals show a potential application as a bioimaging agent. 相似文献