Studying chemical reactions at the nanoscale level could aid to better understand and control reaction processes. In this paper, the redox reaction between hydroquinone and Ag+ via gold nanoparticles ...as a suitable surface was taken as an example, where its thermochemical values were computed by using density functional theory (DFT) methods with the 6-31G(d) basis set. The calculated results exhibited that the reaction kinetics was related to pH values and concluded as three different kinds of processes. Assisted by the gold nanoparticles, we tracked the reduction of Ag+ in real time by plasmon resonance Rayleigh scattering spectroscopy and dark-field microscopy. Moreover, discrete dipole approximation and transmission electron microscope images were also conducted, and the calculated results were in good agreement with the experimental ones. In addition, we utilized the pH response of the redox reaction to distinguish cancer cells from the normal ones, which showed promising applications in promoting the development of disease diagnosis.
Plasmon resonance energy transfer (PRET) has been widely applied in the detection of bio-recognition, heavy metal ions and cellular reactions with high sensitivity, based on the overlap between the ...plasmon resonance scattering band of nanoparticles and the absorption band of the surface-modified chromophore molecules. Previous sensors based on PRET were all implemented on gold nanospheres with scattering light in the range of 530 to 600 nm. In this work, a PRET-based nanosensor was developed on a thiol-di(2-picolyl)amine-modified single gold nanorod for the detection of Cu(2+) ions in aqueous solution with high sensitivity and selectivity. Compared to nanospheres, gold nanorods with tunable and wide plasmon resonance bands from the near-infrared to the infrared region exhibit promising potential for development as sensing probes.
A biological nanopore is one of the predominant single-molecule approaches as a result of its controllable single-biomolecule interface, which could reflect the “intrinsic” information on an ...individual molecule in a label-free way. Because the current blockage is normally treated as the most important parameter for nanopore identification of every single molecule, the fluctuation of current blockage for certain types of molecules, defined as full width at half maximum (fwhm) of current blockage, actually owns a dominant influence on nanopore resolution. Therefore, controlling the fwhm of current blockage of molecules is critical for the sensing capability of the nanopore. Here, taking an aerolysin nanopore as a model, by precisely controlling the functional group in this single-biomolecule interface, we could narrow the fwhm of nanopore current blockage for DNA identification and prolong the duration inside the nanopore. Moreover, a substantial correlation between fwhm of current blockage and duration is established, showing a non-monotonic variation. Besides, the mechanism is also clarified with studying the detailed current blockage events. This proposed correlation is further demonstrated to be applied uniformly across different mutant aerolysins for a certain DNA. This study proposes a new strategy for regulating molecular sensing from the duration of the analyte, which could guide the resolution of heterogeneity analysis using nanopores.
50% diamond particle (5 μm) reinforced 2024 aluminum matrix (diamond/2024 Al) composites were prepared by pressure infiltration method. Diamond particles were distributed uniformly without any ...particle clustering, and no apparent porosities or significant casting defects were observed in the composites. The diamond-Al interfaces of as-cast and annealed diamond/2024 Al composites were clean, smooth and free from interfacial reaction product. However, a large number of Al2Cu precipitates were found at diamond-Al interface after aging treatment. Moreover, needle-shaped Al2MgCu precipitates in Al matrix were observed after aging treatment. The coefficient of thermal expansion (CTE) of diamond/2024 Al composites was about 8.5×10−6 °C−1 between 20 and 100 °C, which was compatible with that with chip materials. Annealing treatment showed little effect on thermal expansion behavior, and aging treatment could further decrease the CTE of the composites. The thermal conductivity of obtained diamond/ 2024 Al composites was about 100 W/(m·K), and it was slightly increased after annealing while decreased after aging treatment.
A new type of online accelerated cooling equipment for seamless steel pipe and its application experiments were introduced in the present work. The equipment can simultaneously cool the inner and ...outer surface of seamless steel pipes. By using online accelerated cooling process, the mechanical properties of the test steel pipe made of Q345B composition meet the requirements of Q460E steel grade index, with the yield strength of 460~475MPa, the tensile strength of 601~603MPa, the elongation of 21.5~26.5%, and the -40°Cimpact energy of 136J.
Quantum dots (QDs) have attracted increasing interest in bioimaging and sensing. Here, we report a biosensor of complex I using ubiquinone-terminated disulphides with different alkyl spacers (QnNS, n ...= 2, 5 and 10) as surface-capping ligands to functionalise CdSe/ZnS QDs. The enhancement or quenching of the QD bioconjugates fluorescence changes as a function of the redox state of QnNS, since QDs are highly sensitive to the electron-transfer processes. The bioconjugated QnNS-QDs emission could be modulated by complex I in the presence of NADH, which simulates an electron-transfer system part of the mitochondrial respiratory chain, providing an in vitro and intracellular complex I sensor. Epidemiological studies suggest that Parkinson's patients have the impaired activity of complex I in the electron-transfer chain of mitochondria. We have demonstrated that the QnNS-QDs system could aid in early stage Parkinson's disease diagnosis and progression monitoring by following different complex I levels in SH-SY5Y cells.
The paper aims to analyze the shielding properties of concrete and lead materials against gamma rays at different energies, and the relationships between the shield thickness of the two materials and ...gamma ray energy and attenuation factor have been obtained by using the method of attenuation multiple and the method of half-value-thickness, respectively. The results show that when the gamma ray energy and the attenuation factor are determined, the thickness of the concrete shield layer obtained by the method of attenuation multiple is greater than that obtained by the half-value-thickness method. The relative magnitude of thickness of lead shield obtained by the method of attenuation multiple and the method of half-value-thickness method is relate to the gamma ray energy. When the gamma ray energy is lower than 8 MeV, the thickness of lead shield calculated by the method of attenuation multiple is larger than that obtained by the half-value-thickness method, while when the gamma ray energy is higher than 8 MeV, the conclusion is opposite.
Herein, the unzipping and translocation of DNA duplexes through a sub-2 nm silicon nitride (SiN
) solid-state nanopore have been demonstrated by well-resolved three-level blockades. In order to ...examine our observations, we applied a simple model which is applicable to the unzipping and translocation processes of DNA duplexes through solid-state nanopores. The generation of these highly recognizable signatures is an important step towards the real applications of solid-state nanopores in complex samples.
To achieve accurate detection of cancer biomarkers with nanopore sensors, the precise recognition of multi-level current blockage events (signature) is a pivotal problem. However, it remains rather a ...challenge to identify the multi-level current blockages of target biomarkers in nanopore experiments, especially for the nanopore analysis of serum samples. In this work, we combined a modified DBSCAN (Density-Based Spatial Clustering of Applications with Noise) algorithm with the Viterbi training algorithm of the hidden Markov model (HMM) to achieve intelligent retrieval of multi-level current signatures from microRNA in serum samples. The results showed that the developed intelligent data analysis method is highly efficient for processing the large-scale nanopore data, which facilitates future application of nanopores to the clinical detection of cancer biomarkers.
分析了城乡有机废弃物如畜禽粪便、农作物秸秆、餐厨垃圾和城市污泥等资源的利用及研究现状，提出了制约有机废弃物资源化利用发展的若干问题，并从法律保障、顶层设计、政策支持和技术发展等方面给出了建议和对策，以期为城乡有机废弃物资源化利用提供参考。 The resource utilization and research status of the main urban and rural ...organic wastes, such as animal excrement, crop straw, kitchen waste and urban sewage sludge, were analyzed. Several problems restricting resource utilization of these organic waste were raised. It also put forward some suggestions and countermeasures from the aspects of legal guarantee, top-level design, policy support and development of technology, in order to provide an important reference for the resource utilization of organic waste in urban and rural areas.
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