A standard errors-in-variables (EIV) model refers to a Gauss–Markov model with an uncertain model matrix from a geodetic perspective. Least squares within the EIV model is usually called the total ...least squares (TLS) technique because of its symmetrical adjustment. However, the solutions and computational advantages of the weighted TLS problem with a general weight matrix (WTLS) are mostly unknown. In this study, the WTLS problem was solved using three different approaches: iterative methods based on the normal equation, the iteratively linearized Gauss–Helmert model with algebraic Jacobian matrices, and numerical analysis. Furthermore, sufficient conditions for WTLS optimization were investigated systematically as proposed solutions yield only necessary conditions for optimality. A WTLS solution was considered to treat random parameters within the EIV model. Last, applications to test these novel algorithms are presented.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
While drinking water disinfection has effectively prevented waterborne diseases, an unintended consequence is the generation of disinfection byproducts (DBPs). Epidemiological studies have ...consistently observed an association between consumption of chlorinated drinking water with an increased risk of bladder cancer. Out of the >600 DBPs identified, regulations focus on a few classes, such as trihalomethanes (THMs), whose concentrations were hypothesized to correlate with the DBPs driving the toxicity of disinfected waters. However, the DBPs responsible for the bladder cancer association remain unclear. Utilities are switching away from a reliance on chlorination of pristine drinking water supplies to the application of new disinfectant combinations to waters impaired by wastewater effluents and algal blooms. In light of these changes in disinfection practice, this article discusses new approaches being taken by analytical chemists, engineers, toxicologists and epidemiologists to characterize the DBP classes driving disinfected water toxicity, and suggests that DBP exposure should be measured using other DBP classes in addition to THMs.
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IJS, KILJ, NUK, PNG, UL, UM
In recent years, strenuous efforts have been devoted to exploring ZnO functionalized TiO2 nanotube arrays (ZnO/TNTs) nanocomposites; however, there is still a paucity of reports on the construction ...of well-defined ZnO/TNTs heterostructure via efficient and easily accessible approach. In this work, drawing on a two-step anodization combined pyrolysis strategy, we attained a highly ordered ZnO/TNTs hybrid nanostructure. Combined with a collection of characterizations including X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), diffusion reflectance spectrum (DRS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), we found that, in this coupling, in situ formed ZnO phases were uniformly grafted to TNTs framework giving rise to hybrid nanostructure, which is ascribed to cooperative interfacial interaction between polar TiO2 layer and ZnO precursor. The underlying interaction leading to judicious combination of TNTs and ZnO was unveiled by Fourier transformed infrared spectrum (FTIR) and XPS. Alternatively, it has been shown that ZnO nanocrystals distributed on the TNTs could serve as favorable hole channels and receptors for efficient separation of photoexcited charge carriers, which results in significantly enhanced photocatalytic performances of ZnO/TNTs heterostructure in comparison with pure TNTs, ZnO film, and P25 particulate film. Furthermore, it is found that the hybrid photocatalyst demonstrated excellent photostability. It is hoped that our work could present a straightforward paradigm for preparation of hierarchical semiconductor/1-D semiconductor heterostructures.
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IJS, KILJ, NUK, PNG, UL, UM
Although recent years have witnessed considerable progress in the synthesis of metal clusters, there is still a paucity of reports on photoelectrochemical (PEC) properties of metal ...cluster/semiconductor systems for solar energy conversion. In this work, highly ordered glutathione (GSH)-protected gold (Au) cluster (Au
@GSH) enwrapped ZnO nanowire array (NW) heterostructures (Au
/ZnO NWs) were designed by a facile, green, simple yet efficient in situ etching-induced electrostatic self-assembly strategy by modulating the intrinsic surface charge properties of building blocks, which renders negatively charged Au
clusters spontaneously and uniformly self-assembles them on positively charged ZnO NWs framework with intimate interfacial integration. It was unraveled that such Au
/ZnO NWs heterostructures demonstrated significantly enhanced PEC water splitting performance in comparison with single ZnO NWs, Au nanoparticles (Au/ZnO NWs) and GSH-capped Ag
clusters (Ag
/ZnO NWs) decorated ZnO NWs counterparts under both simulated solar and visible light irradiation. The vitally important role of Au
clusters as photosensitizer was unambiguously revealed and the merits of Au
clusters in boosting charge transfer arising from their unique core-shell architecture were highlighted by systematic comparison under identical conditions, based on which Au
cluster-mediated PEC water splitting mechanism is delineated. It is anticipated that our work can highlight the possibility of harnessing metal clusters as efficient light-harvest antennas and open new avenues for rational construction of various highly energy efficient metal cluster/semiconductor heterostructures for widespread photocatalytic and PEC applications.
Sentiment analysis or opinion mining is one of the major tasks of NLP (Natural Language Processing). Sentiment analysis has gain much attention in recent years. In this paper, we aim to tackle the ...problem of sentiment polarity categorization, which is one of the fundamental problems of sentiment analysis. A general process for sentiment polarity categorization is proposed with detailed process descriptions. Data used in this study are online product reviews collected from Amazon.com. Experiments for both sentence-level categorization and review-level categorization are performed with promising outcomes. At last, we also give insight into our future work on sentiment analysis.
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CEKLJ, NUK, ODKLJ, UL, UM, UPUK
Recent years have witnessed increasing interest in the solution‐phase synthesis of atomically precise thiolate‐protected gold clusters (Aux); nonetheless, research on the photocatalytic properties of ...Aux–semiconductor nanocomposites is still in its infancy. In this work, recently developed glutathione‐capped gold clusters and highly ordered nanoporous layer‐covered TiO2 nanotube arrays (NP‐TNTAs) are employed as nanobuilding blocks for the construction of a well‐defined Aux/NP‐TNTA heterostructure via a facile electrostatic self‐assembly strategy. Versatile photocatalytic performances of the Aux/NP‐TNTA heterostructure which acts as a model catalyst, including photocatalytic oxidation of organic pollutant, photocatalytic reduction of aromatic nitro compounds and photoelectrochemical (PEC) water splitting under simulated solar light irradiation, are systematically exploited. It is found that synergistic interaction stemming from monodisperse coverage of Aux clusters on NP‐TNTAs in combination with hierarchical nanostructure of NP‐TNTAs reinforce light absorption of Aux/NP‐TNTA heterostructure especially within visible region, hence contributing to the significantly enhanced photocatalytic and PEC water splitting performances. Moreover, photocatalytic and PEC mechanisms over Aux/NP‐TNTA heterostructure are elucidated and corresponding reaction models were presented. It is anticipated that this work could boost new insight for photocatalytic properties of metal‐cluster‐sensitized semiconductor nanocomposites.
A well‐defined heterostructure consisting of monodisperse Au clusters and hierarchically ordered nanoporous TiO2 nanotube arrays (Aux/NP‐TNTAs) is fabricated via a facile two‐step anodization approach combined with efficient electrostatic self‐assembly. The hierarchically ordered Aux/NP‐TNTA heterostructure demonstrates versatile photocatalytic redox and photoelectrochemical performances under simulated solar light irradiation under ambient conditions.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Atomically precise metal nanoclusters (NCs) have garnered tremendous attention as light‐harvesting antennas in heterogeneous photocatalysis due to unique atomic stacking mode, quantum confinement ...effect, and enriched active sites. However, metal NCs as photosensitizers suffer from extremely short carrier lifetime, poor photostability, and difficulty in carrier migration, which hinder the wide‐spread utilization of metal NCs in solar energy conversion. To solve these problems, herein, Ag‐doped glutathione (GSH)‐capped gold NCs, i.e., alloy Au1−xAgx@GSH NCs and non‐conjugated insulating polymer of poly(diallyl‐dimethylammonium chloride) (PDDA) are utilized as the building blocks for layer‐by‐layer assembly of spatially multilayered alloy NCs/metal oxide (MO) photosystems. The alternately deposited ultrathin PDDA layer in‐between Au1−xAgx@GSH NCs on the MO substrate functions as an efficient charge flow mediator to relay the directional photoelectron transfer over Au1−xAgx@GSH NCs, giving rise to the cascade charge transfer chain. This peculiar carrier migration mode endowed by exquisite interface configuration design significantly boosts the unidirectional electron migration from the Au1−xAgx@GSH NCs to the MO substrate, substantially improving the visible‐light‐driven photoelectrochemical water oxidation performances of MO/(PDDA‐Au1−xAgx)n multilayer heterostructured photoanodes. The work will inspire the rational construction of alloy metal NCs‐based photosystems for modulating spatially controllable charge transfer pathway for solar energy conversion.
Cascade charge transfer channel is elaborately designed over alloy nanoclusters via a facile, easily accessible, and efficient layer‐by‐layer assembly strategy for boosted photoelectrochemical water oxidation. The favorable energy level alignment between metal oxide and atomically precise alloy nanoclusters stimulates the advantageous interfacial charge migration and separation, prolonging the charge lifetime.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Synthetic DNA motors have great potential to mimic natural protein motors in cells but the operation of synthetic DNA motors in living cells remains challenging and has not been demonstrated. Here we ...report a DNAzyme motor that operates in living cells in response to a specific intracellular target. The whole motor system is constructed on a 20 nm gold nanoparticle (AuNP) decorated with hundreds of substrate strands serving as DNA tracks and dozens of DNAzyme molecules each silenced by a locking strand. Intracellular interaction of a target molecule with the motor system initiates the autonomous walking of the motor on the AuNP. An example DNAzyme motor responsive to a specific microRNA enables amplified detection of the specific microRNA in individual cancer cells. Activated by specific intracellular targets, these self-powered DNAzyme motors will have diverse applications in the control and modulation of biological functions.
In recent years, increasing interest has been devoted to synthesizing graphene–semiconductor nanocomposites as efficient photocatalysts for extensive applications. Unfortunately, it is still ...challenging to make uniform graphene–semiconductor composite films with controllable film thickness and architecture, which are of paramount importance to meet the application requirements. In this work, stable aqueous dispersion of polymer-modified graphene nanosheets (GNs) was prepared via in situ reduction of exfoliated graphite oxide in the presence of cationic poly(allylamine hydrochloride) (PAH). The resultant water-soluble PAH-modified GNs (GNs-PAH) in conjunction with tailor-made negatively charged CdS quantum dots (QDs) were utilized as nanobuilding blocks for sequential layer-by-layer (LbL) self-assembly of well-defined GNs–CdS QDs hybrid films, in which CdS QDs overspread evenly on the two-dimensional (2D) GNs. It was found that the alternating GNs–CdS QDs multilayered films showed significantly enhanced photoelectrochemical and photocatalytic activities under visible light irradiation as compared to pure CdS QDs and GNs films. The enhancement was attributed to the judicious integration of CdS QDs with GNs in an alternating manner, which maximizes the 2D structural advantage of GNs in GNs–CdS QDs composite films. In addition, photocatalytic and photoelectrochemical mechanisms of the GNs–CdS QDs multilayered films were also discussed. It is anticipated that our work may open new directions for the fabrication of uniform semiconductor/GNs hybrid films for a wide range of applications.
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IJS, KILJ, NUK, PNG, UL, UM
Atomically precise metal nanoclusters (NCs) represent a promising generation of metal nanomaterial because of characteristic atomic stacking mode, abundant catalytic active sites, and molecular‐like ...discrete energy band structure. However, crafting metal NCs‐dominated photocatalytic systems with mediated charge transport pathways for photoredox catalysis is in the infant stage and their photocatalytic mechanisms remain elusive, which is largely hampered by the ultra‐short charge lifetime, generic instability, and complicated electronic structure of metal NCs. In this study, the smart construction of all‐solid‐state metal NCs‐transition metal chalcogenides quantum dots (TMCs QDs) Z‐scheme artificial photosystems for robust and stable solar‐to‐hydrogen conversion is demonstrated. The concurrent favorable photosensitization efficiency of metal NCs and TMCs QDs synergistically stimulate the unexpected Z‐scheme charge transport pathway, which significantly boosts the anisotropic spatial vectorial charge transport/separation, giving rise to considerably enhanced visible‐light‐responsive photocatalytic hydrogen generation performances along with favorable stability. This study would push forward the prosperity of exploring metal NCs‐based photosystems for solar‐to‐hydrogen conversion.
Atomically precise metal nanoclusters mediated Z‐scheme photosystems are for the first time exquisitely crafted for solar‐to‐hydrogen conversion. The favorable energy level alignment among Au25(GSH)18 nanoclusters, CdSe QDs, and MoSe2 along with elegant interface configuration modulation facilitates the directional charge migration and separation, giving rise to high‐performance Z‐scheme photosystem for photocatalytic hydrogen generation under visible light irradiation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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