This article examines the three-way relationship between right coherency of a monoid S, solutions of equations over S-acts, and injectivity properties of S-acts. A monoid S is right coherent if every ...finitely generated subact of every finitely presented (right) S-act itself has a finite presentation. Purity properties of an S-act A may either be expressed in terms of solutions in A of certain consistent sets of equations over A, or in terms of injectivity properties. For example, an S-act A is absolutely pure (almost pure) if every finite consistent set of equations over A (in one variable) has a solution in A. Equivalently, A is absolutely pure (almost pure) if it is injective with respect to inclusions of finitely generated subacts into finitely presented (monogenic finitely presented) S-acts.
Our first main result shows that for a right coherent monoid S the classes of almost pure and absolutely pure S-acts coincide. Our second main result is that a monoid S is right coherent if and only if the classes of mfp-pure and absolutely pure S-acts coincide: an S-act is mfp-pure if it is injective with respect to inclusions of finitely presented subacts into monogenic finitely presented S-acts. We give specific examples of monoids S that are not right coherent yet are such that the classes of almost pure and absolutely pure S-acts coincide. Finally we give a condition on a monoid S for all almost pure S-acts to be absolutely pure in terms of finitely presented S-acts, their finitely generated subacts, and certain canonical extensions.
All inorganic halide perovskite (IHP) nanocrystals (NCs) have emerged as a new class of optoelectronic materials for various applications. Surface ligands as surface passivators are essential ...components of nucleation and growth processes, photoluminescence quantum yields (PL QY), stability, and photoelectric applications. In this review, the relationship of perovskite structure modified is outlined by surface ligand and some properties on account of the ion structure features. This review specifically focuses on the roles of surface ligands in the construction of IHP NCs with fewer defects, higher PL QY, and better stability. Generally, ligands binding to the surface of IHP NCs can form passivation layer, which are beneficial to not only the improvement of PL QY by filling the Br− or Pb2+ vacancy but also the enhancement of stability. The surface passivation mechanisms are attributed to the Br⋯HN+ hydrogen‐bonding, chelation, and dative covalent bond interactions. Furthermore, degradation mechanisms assigned to the hydration, ion migration, and dissociation are discussed. The equilibrium problem of purifying and QY and possible reasons are also addressed, which are believed to be solved in the near future with the help of coordination chemistry and surface engineering. Finally, a brief outlook including challenges and possible development is provided.
The instability of CsPbBr3 nanocrystals (NCs) is attributed to not only the internal crystal structure feature but also to the external factors including the illumination, humidity, oxygen, and UV, which lead to the degradation and photoluminescence (PL) loss of CsPbBr3 NCs. Therefore, surface passivation plays a crucial role in the improvement of PL quantum yield, stability, and device performance.
The stability and optoelectronic device performance of perovskite quantum dots (Pe‐QDs) are severely limited by present ligand strategies since these ligands exhibit a highly dynamic binding state, ...resulting in serious complications in QD purification and storage. Here, a “Br‐equivalent” ligand strategy is developed in which the proposed strong ionic sulfonate heads, for example, benzenesulfonic acid, can firmly bind to the exposed Pb ions to form a steady binding state, and can also effectively eliminate the exciton trapping probability due to bromide vacancies. From these two aspects, the sulfonate heads play a similar role as natural Br ions in a perfect perovskite lattice. Using this approach, high photoluminescence quantum yield (PL QY) > 90% is facilely achieved without the need for amine‐related ligands. Furthermore, the prepared PL QYs are well maintained after eight purification cycles, more than five months of storage, and high‐flux photo‐irradiation. This is the first report of high and versatile stabilities of Pe‐QD, which should enable their improved application in lighting, displays, and biologic imaging.
A new equivalent ligand strategy with a strong ionic sulfonate head is demonstrated and the purification and storage problems of perovskite nanocrystals are overcome. Both theoretical and experimental results prove the elimination of nonradiative recombination and high quantum efficiency are maintained throughout purification, storage, and irradiation.
Fucosylation is the process of transferring fucose from GDP-fucose to their substrates, which includes certain proteins, N- and O-linked glycans in glycoprotein or glycolipids, by fucosyltransferases ...in all mammalian cells. Fucosylated glycans play vital role in selectin-mediated leukocyte extravasation, lymphocyte homing, and pathogen-host interactions, whereas fucosylated proteins are essential for signaling transduction in numerous ontogenic events. Aberrant fucosylation due to the availability of high energy donor GDP-fucose, abnormal expression of FUTs and/or α-fucosidase, and the availability of their substrates leads to different fucosylated glycan or protein structures. Accumulating evidence demonstrates that aberrant fucosylation plays important role in all aspects of cancer biology. In this review, we will summarize the current knowledge about fucosylation in different physiological and pathological processes with a focus on their roles not only in cancer cell proliferation, invasion, and metastasis but also in tumor immune surveillance. Furthermore, the clinical potential and applications of fucosylation in cancer diagnosis and treatment will also be discussed.
With growing demand for propylene and increasing production of propane from shale gas, the technologies of propylene production, including direct dehydrogenation and oxidative dehydrogenation of ...propane, have drawn great attention in recent years. In particular, direct dehydrogenation of propane to propylene is regarded as one of the most promising methods of propylene production because it is an on-purpose technique that exclusively yields propylene instead of a mixture of products. In this critical review, we provide the current investigations on the heterogeneous catalysts (such as Pt, CrOx, VOx, GaOx-based catalysts, and nanocarbons) used in the direct dehydrogenation of propane to propylene. A detailed comparison and discussion of the active sites, catalytic mechanisms, influencing factors (such as the structures, dispersions, and reducibilities of the catalysts and promoters), and supports for different types of catalysts is presented. Furthermore, rational designs and preparation of high-performance catalysts for propane dehydrogenation are proposed and discussed.
This review presents the state-of-the-art catalysts (including Pt, CrOx, VOx, GaOx, ZnO, FeOx, CoOx, SnOx, ZrO2-based catalysts, and nanocarbons) that have been reported in recent years for direct dehydrogenation of propane to propylene.
Analyzing customers' characteristics and giving the early warning of customer churn based on machine learning algorithms, can help enterprises provide targeted marketing strategies and personalized ...services, and save a lot of operating costs. Data cleaning, oversampling, data standardization and other preprocessing operations are done on 900,000 telecom customer personal characteristics and historical behavior data set based on Python language. Appropriate model parameters were selected to build BPNN (Back Propagation Neural Network). Random Forest (RF) and Adaboost, the two classic ensemble learning models were introduced, and the Adaboost dual-ensemble learning model with RF as the base learner was put forward. The four models and the other four classical machine learning models-decision tree, naive Bayes, K-Nearest Neighbor (KNN), Support Vector Machine (SVM) were utilized respectively to analyze the customer churn data. The results show that the four models have better performance in terms of recall rate, precision rate, F1 score and other indicators, and the RF-Adaboost dual-ensemble model has the best performance. Among them, the recall rates of BPNN, RF, Adaboost and RF-Adaboost dual-ensemble model on positive samples are respectively 79%, 90%, 89%,93%, the precision rates are 97%, 99%, 98%, 99%, and the F1 scores are 87%, 95%, 94%, 96%. The RF-Adaboost dual-ensemble model has the best performance, and the three indicators are 10%, 1%, and 6% higher than the reference. The prediction results of customer churn provide strong data support for telecom companies to adopt appropriate retention strategies for pre-churn customers and reduce customer churn.
Previous studies have revealed the critical roles of N6-methyladenosine (m6A) modification of mRNA in embryonic stem cells (ESCs), but the biological function of m6A in large intergenic noncoding RNA ...(lincRNA) is unknown. Here, we showed that the internal m6A modification of linc1281 mediates a competing endogenous RNA (ceRNA) model to regulate mouse ESC (mESC) differentiation. We demonstrated that loss of linc1281 compromises mESC differentiation and that m6A is highly enriched within linc1281 transcripts. Linc1281 with RRACU m6A sequence motifs, but not an m6A-deficient mutant, restored the phenotype in linc1281-depleted mESCs. Mechanistic analyses revealed that linc1281 ensures mESC identity by sequestering pluripotency-related let-7 family microRNAs (miRNAs), and this RNA-RNA interaction is m6A dependent. Collectively, these findings elucidated the functional roles of linc1281 and its m6A modification in mESCs and identified a novel RNA regulatory mechanism, providing a basis for further exploration of broad RNA epigenetic regulatory patterns.
•Co, Mn-LDH nanoneedle arrays grown on Ni foam with strong adhesion is fabricated.•The unique structure had good conductivity, and relieved volume change.•It exhibits large specific capacitance, ...superior rate capability and cyclability.
To solve the agglomeration of layered double hydroxides (LDH) for improving their supercapacitor performances, Co, Mn-LDH nanoneedle arrays grown on Ni foam (Co, Mn-LDH@NF hybrid) was fabricated via a one-step hydrothermal strategy. The Ni foam served as the skeleton frame for anchoring Co, Mn-LDH nanoneedles to form three dimensional net structures, and open spaces among Co, Mn-LDH nanoneedles. When Co, Mn-LDH@NF hybrid was used as binder-free electrodes for supercapacitors, it displayed outstanding supercapacitor performances with a high specific capacitance of 2422 F g−1 at 1 A g−1, and superior cyclic stability for maintaining a capacitance of 2096 F g−1 after 3000 cycles, which was only 13.5% capacity loss ratio. The excellent supercapacitor performances were ascribed to three dimensional net structure and LDH nanoneedle structure, which provided abundant electrochemical active sites, alleviated volume expansion, and had good electrical conductivity.
Candida albicans is a benign member of gut microbiota, but also causes life-threatening disseminated infections, suggesting that this fungus commensalism has evolved with retention of virulence ...traits. Here we reveal that N-acetylglucosamine (GlcNAc) enables C. albicans to balance between commensalism and pathogenesis. Although GlcNAc catabolism is beneficial for commensal growth of C. albicans, deleting GlcNAc sensor-transducer Ngs1 confers enhanced fitness, indicating that GlcNAc signaling is detrimental to commensalism. Interestingly, addition of GlcNAc attenuates commensal fitness of gut-evolved C. albicans but retains its disease-causing potential. We further demonstrate that GlcNAc is a major inducer of hypha-associated transcription in the gut, which represents the key determinant for commensal-pathogenic equilibrium. In addition to yeast-to-hypha morphogenesis, we also identify other factors, including Sod5 and Ofi1, that contribute to the balance. Thus, C. albicans uses GlcNAc to build up a tradeoff between fungal programs supporting commensalism and virulence, which may explain its success as a commensal and pathogen.
Abstract
Fluorescent type nuclear battery consisting of scintillator and photovoltaic device enables semipermanent power source for devices working under harsh circumstances without instant energy ...supply. In spite of the progress of device structure design, the development of scintillators is far behind. Here, a Cs
3
Cu
2
I
5
: Mn scintillator showing a high light yield of ~67000 ph MeV
−1
at 564 nm is presented. Doping and intrinsic features endow Cs
3
Cu
2
I
5
: Mn with robust thermal stability and irradiation hardness that 71% or >95% of the initial radioluminescence intensity can be maintained in an ultra-broad temperature range of 77 K-433 K or after a total irradiation dose of 2590 Gy, respectively. These superiorities allow the fabrication of efficient and stable nuclear batteries, which show an output improvement of 237% respect to the photovoltaic device without scintillator. Luminescence mechanisms including self-trapped exciton, energy transfer, and impact excitation are proposed for the anomalous dramatic radioluminescence improvement. This work will open a window for the fields of nuclear battery and radiography.
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