Long-term impacts of reservoir operation on the spatiotemporal variation in nitrogen forms in the post-Three Gorges Dam period (2004-2016).

Nitrogen (N) is an essential nutrient limiting life, and its biochemical cycling and distribution in rivers have been markedly affected by river engineering construction and operation. Here, we comprehensively analyzed the spatiotemporal variations and driving environmental factors of N distributions based on the long-term observations (from 2004 to 2016) of seven stations in the Three Gorges Reservoir (TGR). In the study period, several water quality indexes of the river reach improved, whereas N pollution was severe and tended to be aggravated after the TGR impoundment.

Visible-light driven photodegradation on Ag nanoparticle-embedded fullerene (C) heterostructural microcubes.

Three-dimensional Ag(I)-fullerene hybrid microcrystal is fabricated by AgNO assisted liquid-liquid interfacial precipitation, containing the abundant sp-π-electron system. With a mild chemical reduction, it produces the massive Ag nanocluster/fullerene junctions, on which fullerene doubles role as the excellent electron acceptor and photon scavenger, enabling the Plasmon-driven catalytic reaction. Ag nanocluster employed alone could not perform this photocatalytic reaction, neither of fullerene (C) crystal.

Ag(I)-Hived Fullerene Microcube as an Enhanced Catalytic Substrate for the Reduction of 4-Nitrophenol and the Photodegradation of Orange G Dye.

We report a facile approach to fabricate an Ag-embedded fullerene (C) catalyst by the chemical reduction of the AgNO complex encapsulated fullerene microcrystal, which showed an enhanced catalytic reduction of 4-nitrophenol because of the strong absorption and propagation of H along the fullerene surface. With the aid of visible-light radiation, photodegradation of orange G dye is achieved through the formation of an electron donor-acceptor dyad between plasmon Ag nanostructures and fullerene molecules, which effectively offsets the "electron-hole" recombination. Neither Ag nanoparticle nor fullerene crystal used in isolation could perform this chemical conversion, implying that the metal-fullerene hybrid structure is imperative for performing the catalytic reaction.

Unraveling a self-assembling mechanism of isomeric aminothiophenol on Ag dendrite by correlated SERS and matrix-free LDI-MS.

Correlated spectroscopic analysis can provide complementary chemical insights that are often unattainable by either approach used in isolation. We distinguished the different self-assembling behavior of isomeric aminothiophenols (ATPs) on Ag dendrite by the correlation of surface-enhanced Raman spectroscopy and laser-induced desorption ionization mass spectrometry, demonstrating that steric effect impinged significantly upon surface molecular density and plasmon-driven catalytic reaction yield, which led to drastic variations in the resulting SERS spectra. The correlative measurement shows that ortho-substitute barely formed a self-assemble monolayer, relative to the para-isomer, which can form a close-packed self-assembled monolayer and perform a decent azo-coupling reaction.

Quantitative Determining of Ultra-Trace Aluminum Ion in Environmental Samples by Liquid Phase Microextraction Assisted Anodic Stripping Voltammetry.

Direct detecting of trace amount Al(III) in aqueous solution by stripping voltammetry is often frustrated by its irreversible reduction, resided at −1.75 V (vs. Ag/AgCl reference), which is in a proximal potential of proton reduction.

Surface invasive cleavage assay on a maskless light-directed diamond DNA microarray for genome-wide human SNP mapping.

The surface invasive cleavage assay, because of its innate accuracy and ability for self-signal amplification, provides a potential route for the mapping of hundreds of thousands of human SNP sites. However, its performance on a high density DNA array has not yet been established, due to the unusual "hairpin" probe design on the microarray and the lack of chemical stability of commercially available substrates. Here we present an applicable method to implement a nanocrystalline diamond thin film as an alternative substrate for fabricating an addressable DNA array using maskless light-directed photochemistry, producing the most chemically stable and biocompatible system for genetic analysis and enzymatic reactions.

Nanoporous GaN-Ag composite materials prepared by metal-assisted electroless etching for direct laser desorption-ionization mass spectrometry.

Three-dimensional nanoporous gallium nitride(PGaN) produced by metal-assisted electroless etching is chemically embedded with silver nanoparticles via electroless deposition, forming a metallized semiconductor membrane with large surface area and nanoscale metal features. A new application utilizing the unique chemical and morphological features of these composite nanostructures is described here, laser induced desorption-ionization(LDI) of biomolecules(e.g.

Correlation of surface-enhanced Raman spectroscopy and laser desorption-ionization mass spectrometry acquired from silver nanoparticle substrates.

Applying complementary experiments, like laser desorption-ionization mass spectrometry (LDI-MS) and confocal surface-enhanced Raman microscopy, to the same physical sample location has the potential to elucidate the behavior of complex chemical and biochemical systems in ways that are not available to either method applied in isolation. In these experiments surface-enhanced Raman scattering (SERS) and LDI-MS are applied to the same sample spot using a common structure, deposited Ag colloids, both as ionization matrix and simultaneously as enhancing media for surface-enhanced Raman scattering of small organic molecules, dyes and lipids, and the behavior is compared. Three compounds-p-aminothiophenol (ATP), rhodamine 6G and cholesterol-which exhibit different strengths of interaction with Ag are examined in detail by correlated SERS and LDI-MS.

Quantitative high-performance liquid chromatography-electrospray ionization tandem mass spectrometry analysis of bis-N7-guanine DNA-DNA cross-links in white blood cells of cancer patients receiving cyclophosphamide therapy.

Cyclophosphamide (CPA) is a DNA alkylating agent widely used in cancer chemotherapy. CPA undergoes metabolic activation to phosphoramide mustard and nornitrogen mustard (NOR) which alkylate the N-7 position of guanine in DNA to produce N-[2-(N7-guaninyl) ethyl]-N-[2-hydroxyethyl]-amine (G-NOR-OH) monoadducts and N,N-bis[2-(N7-guaninyl) ethyl] amine cross-links (G-NOR-G). G-NOR-G cross-links are strongly cytotoxic and are thought to be responsible for the biological activity of CPA.

Targeted quantitative analysis of superoxide dismutase 1 in cisplatin-sensitive and cisplatin-resistant human ovarian cancer cells.

Protein quantification in a complex protein mixture presents a daunting task in biochemical analysis. Antibody-based immunoassays are traditional methods for protein quantification. However, there are issues associated with accuracy and specificity in these assays, especially when the changes are small (e.

Targeting superoxide dismutase 1 to overcome cisplatin resistance in human ovarian cancer.

Purpose: Clinical drug resistance to platinum-based chemotherapy is considered a major impediment in the treatment of human ovarian cancer. Multiple pathways associated with drug resistance have been suggested by many previous studies. Over expression of several key proteins involved in DNA repair, drug transport, redox regulation, and apoptosis has been recently reported by our group using a global quantitative proteomic profiling approach.

Quantitative detection of individual cleaved DNA molecules on surfaces using gold nanoparticles and scanning electron microscope imaging.

Single-nucleotide polymorphisms (SNPs) are the most frequent type of human genetic variation. Recent work has shown that it is possible to directly analyze SNPs in unamplified human genomic DNA samples using the surface-invasive cleavage reaction followed by rolling circle amplification (RCA) labeling of the cleavage products. The individual RCA amplicon molecules were counted on the surface using fluorescence microscopy.

Scoring single-nucleotide polymorphisms at the single-molecule level by counting individual DNA cleavage events on surfaces.

Single-nucleotide polymorphisms (SNPs) are the most frequent type of human genetic variation. Recent work has shown that it is possible to directly analyze SNPs in unamplified human genomic DNA samples using the surface-invasive cleavage reaction followed by rolling circle amplification (RCA) of the cleavage products. The ability of RCA to produce single-stranded DNA tens of thousands of nucleotides in length from a single cleaved DNA molecule on the surface suggested the possibility of detecting individual cleavage events on the surface.