Solar-driven water splitting provides a leading approach to store the abundant yet intermittent solar energy and produce hydrogen as a clean and sustainable energy carrier. A straightforward route to ...light-driven water splitting is to apply self-supported particulate photocatalysts, which is expected to allow solar hydrogen to be competitive with fossil-fuel-derived hydrogen on a levelized cost basis. More importantly, the powder-based systems can lend themselves to making functional panels on a large scale while retaining the intrinsic activity of the photocatalyst. However, all attempts to generate hydrogen via powder-based solar water-splitting systems to date have unfortunately fallen short of the efficiency values required for practical applications. Photocatalysis on photocatalyst particles involves three sequential steps: (i) absorption of photons with higher energies than the bandgap of the photocatalysts, leading to the excitation of electron–hole pairs in the particles, (ii) charge separation and migration of these photoexcited carriers, and (iii) surface chemical reactions based on these carriers. In this review, we focus on the challenges of each step and summarize material design strategies to overcome the obstacles and limitations. This review illustrates that it is possible to employ the fundamental principles underlying photosynthesis and the tools of chemical and materials science to design and prepare photocatalysts for overall water splitting.
Iron metabolism in inflammation has been mostly characterized in macrophages exposed to pathogens or inflammatory conditions. The aim of this study is to investigate the cross-regulatory interactions ...between M1 macrophage polarization and iron metabolism. Firstly, we characterized the transcription of genes related to iron homeostasis in M1 RAW264.7 macrophages stimulated by IFN-γ. The molecular signature of M1 macrophages showed high levels of iron storage (ferritin), a low level of iron export (ferroportin), and changes of iron regulators (hepcidin and transferrin receptors), which favour iron sequestration in the reticuloendothelial system and are benefit for inflammatory disorders. Then, we evaluated the effect of iron on M1 macrophage polarization. Iron significantly reduced mRNA levels of IL-6, IL-1β, TNF-α, and iNOS produced by IFN-γ-polarized M1 macrophages. Immunofluorescence analysis showed that iron also reduced iNOS production. However, iron did not compromise but enhanced the ability of M1-polarized macrophages to phagocytose FITC-dextran. Moreover, we demonstrated that STAT1 inhibition was required for reduction of iNOS and M1-related cytokines production by the present of iron. Together, these findings indicated that iron decreased polarization of M1 macrophages and inhibited the production of the proinflammatory cytokines. The results expanded our knowledge about the role of iron in macrophage polarization.
Zero-shot learning for visual recognition, e.g., object and action recognition, has recently attracted a lot of attention. However, it still remains challenging in bridging the semantic gap between ...visual features and their underlying semantics and transferring knowledge to semantic categories unseen during learning. Unlike most of the existing zero-shot visual recognition methods, we propose a stagewise bidirectional latent embedding framework of two subsequent learning stages for zero-shot visual recognition. In the bottom–up stage, a latent embedding space is first created by exploring the topological and labeling information underlying training data of known classes via a proper supervised subspace learning algorithm and the latent embedding of training data are used to form landmarks that guide embedding semantics underlying unseen classes into this learned latent space. In the top–down stage, semantic representations of unseen-class labels in a given label vocabulary are then embedded to the same latent space to preserve the semantic relatedness between all different classes via our proposed semi-supervised Sammon mapping with the guidance of landmarks. Thus, the resultant latent embedding space allows for predicting the label of a test instance with a simple nearest-neighbor rule. To evaluate the effectiveness of the proposed framework, we have conducted extensive experiments on four benchmark datasets in object and action recognition, i.e., AwA, CUB-200-2011, UCF101 and HMDB51. The experimental results under comparative studies demonstrate that our proposed approach yields the state-of-the-art performance under inductive and transductive settings.
Due to the increasing popularity of cloud computing, more and more data owners are motivated to outsource their data to cloud servers for great convenience and reduced cost in data management. ...However, sensitive data should be encrypted before outsourcing for privacy requirements, which obsoletes data utilization like keyword-based document retrieval. In this paper, we present a secure multi-keyword ranked search scheme over encrypted cloud data, which simultaneously supports dynamic update operations like deletion and insertion of documents. Specifically, the vector space model and the widely-used TF x IDF model are combined in the index construction and query generation. We construct a special tree-based index structure and propose a "Greedy Depth-first Search" algorithm to provide efficient multi-keyword ranked search. The secure kNN algorithm is utilized to encrypt the index and query vectors, and meanwhile ensure accurate relevance score calculation between encrypted index and query vectors. In order to resist statistical attacks, phantom terms are added to the index vector for blinding search results. Due to the use of our special tree-based index structure, the proposed scheme can achieve sub-linear search time and deal with the deletion and insertion of documents flexibly. Extensive experiments are conducted to demonstrate the efficiency of the proposed scheme.
Cuprotosis is a mode of cell death triggered by copper accumulation. There is a lack of studies on the role of cuprotosis-related lncRNA in acute myeloid leukaemia (AML).
Expression data and ...corresponding clinical data of lncRNA and mRNA were sourced from TCGA database. Pearson's correlation, differential expression, univariate Cox regression, and least absolute shrinkage and selection operator (LASSO) analysis were performed to screen for a cuprotosis-related lncRNA signature and to evaluate its prognostic significance. A prognostic model was constructed, and patients were categorized into high- and low-risk groups according to their calculated risk scores. The model's performance was then assessed in internal training, and internal and external testing sets. The high- and low- risk groups were examined to explore their involvement in AML. The relationship between the risk score and various clinical parameters, mutational landscapes, immune cell scores, and drug sensitivity were investigated.
Five cuprotosis-related lncRNAs (AC020571.3, CTD-2325M2.1, RP11-802O23.3, RP11-474N24.6, and UCA1) were identified, which were differentially expressed in AML datasets in comparison to normal controls and significantly associated with prognosis. Consistent with the results obtained from the training and testing sets, the high-risk group had a poor prognosis with good predictive power. The high- and low-risk groups differed significantly in immune-related biological processes and the IC50 values of WH-4.023, mitomycin C, navitoclaxin, and PD-0325901.
Five cuprotosis-related lncRNA signatures were screened as prognostic predictors to provide new insights into lncRNA-based diagnostic and therapeutic strategies for AML.
Linguistic expressions of interest instantiated by
interesting
,
intriguing
, and
fascinating
that signal the authorial stance are not uncommon in applied linguistics research articles. Nevertheless, ...they have received little scholarly attention. This paper, taking a cognitive semantic approach, reports on a study that sought to examine how linguistically expressed interest in applied linguistics research articles is leveraged by researchers’ geo-academic location (the Core vs. the Periphery). Drawing on a semantic frame generated for interest markers in academic writing, this study focused on the incidence of the various elements of the Interest frame in the discipline of applied linguistics based on a mixed-methods approach. The corpus-based quantitative analyses found that academic writers’ geo-academic location was a robust predictor of authors’ overall use of interest markers and some frame elements associated with the Interest frame. Triangulation with the interview data obtained from disciplinary specialists revealed that the observed differences could be attributable to the hierarchical academia featuring periphery-based scholars’ unequal access to the knowledge production market and under-representation.
We systematically study the chaotic signatures in a quantum many-body system consisting of an ensemble of interacting two-level atoms coupled to a single-mode bosonic field, the so-called extended ...Dicke model. The presence of the atom-atom interaction also leads us to explore how the atomic interaction affects the chaotic characters of the model. By analyzing the energy spectral statistics and the structure of eigenstates, we reveal the quantum signatures of chaos in the model and discuss the effect of the atomic interaction. We also investigate the dependence of the boundary of chaos extracted from both eigenvalue-based and eigenstate-based indicators on the atomic interaction. We show that the impact of the atomic interaction on the spectral statistics is stronger than on the structure of eigenstates. Qualitatively, the integrablity-to-chaos transition found in the Dicke model is amplified when the interatomic interaction in the extended Dicke model is switched on.
Power train electrification is promoted as a potential alternative to reduce carbon intensity of transportation. Lithium-ion batteries are found to be suitable for hybrid electric vehicles (HEVs) and ...pure electric vehicles (EVs), and temperature control on lithium batteries is vital for long-term performance and durability. Unfortunately, battery thermal management (BTM) has not been paid close attention partly due to poor understanding of battery thermal behaviour. Cell performance change dramatically with temperature, but it improves with temperature if a suitable operating temperature window is sustained. This paper provides a review on two aspects that are battery thermal model development and thermal management strategies. Thermal effects of lithium-ion batteries in terms of thermal runaway and response under cold temperatures will be studied, and heat generation methods are discussed with aim of performing accurate battery thermal analysis. In addition, current BTM strategies utilised by automotive suppliers will be reviewed to identify the imposing challenges and critical gaps between research and practice. Optimising existing BTMs and exploring new technologies to mitigate battery thermal impacts are required, and efforts in prioritising BTM should be made to improve the temperature uniformity across the battery pack, prolong battery lifespan, and enhance the safety of large packs.
Lattice thermal conductivity of penta-graphene Wang, Fancy Qian; Yu, Jiabing; Wang, Qian ...
Carbon (New York),
August 2016, 2016-08-00, 2016-08-01, Volume:
105, Issue:
C
Journal Article
Peer reviewed
Open access
Motivated by the unique geometry and novel properties of penta-graphene proposed recently as a new carbon allotrope consisting of pure pentagons Zhang et al. Proc. Natl. Acad. Sci. 2015, 112, 2372, ...we systematically investigated its phonon transport properties by solving exactly the linearized phonon Boltzmann transport equation combined with first principles calculations. The intrinsic lattice thermal conductivity Klat of penta-graphene is found to be about 645 W/mK at room temperature, which is significantly reduced as compared to that of graphene. The underlying reason is the strong anharmonic effect introduced by the buckled pentagonal structure with hybridized sp2 and sp3 bonding. A detailed analysis of the phonons of penta-graphene reveals that the ZA mode is the primary heat carrier (nearly 60%). The Klat is dominated by three-phonon scattering where the scattering rate of the Normal scattering process is comparable to that of the Umklapp scattering process. The phonon mean free path of the collective phonon excitations is in the order of micrometers. Complementing the high thermal conductivity of graphene, the low thermal conductivity of penta-graphene adds additional features to the family of carbon materials for thermal applications.
ABSTRACT We present results from a deep Chandra X-ray observation of a merging galaxy cluster A520. A high-resolution gas temperature map reveals a long trail of dense, cool clumps-apparently the ...fragments of a cool core that has been stripped from the infalling subcluster by ram pressure. The clumps should still be connected by the stretched magnetic field lines. The observed temperature variations imply that thermal conductivity is suppressed by a factor across the presumed direction of the magnetic field (as found in other clusters), and is also suppressed along the field lines by a factor of several. Two massive clumps in the periphery of A520, visible in the weak-lensing mass map and the X-ray image, have apparently been completely stripped of gas during the merger, but then re-accreted the surrounding high-entropy gas upon exit from the cluster. The mass clump that hosted the stripped cool core is also reaccreting hotter gas. An X-ray hydrostatic mass estimate for the clump that has the simplest geometry agrees with the lensing mass. Its current gas mass to total mass ratio is very low, 1.5%-3%, which makes it a "dark subcluster." We also found a curious low X-ray brightness channel (likely a low-density sheet in projection) going across the cluster along the direction of an apparent secondary merger. The channel may be caused by plasma depletion in a region of an amplified magnetic field (with plasma ). The shock in A520 will be studied in a separate paper.
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