Bi- and tri-dentate imino-based iron and cobalt pre-catalysts for ethylene oligo-/polymerization

Recent progress on the use of iron and cobalt complex pre-catalysts for ethylene reactivity is reviewed. The review is organized in terms of the denticity of the chelate ligands employed, with particular reference to the influence of the ligand frameworks and their substituents on the catalytic performance for ethylene oligomerization/polymerization catalysis. The majority of the systems bear tri-dentate ligation at the iron/cobalt centre, though it is clear that bi-dentate iron/cobalt complex pre-catalysts have also attracted significant attention. Such systems produce in most cases highly linear products ranging from oligomeric α-olefins to high molecular weight polyethylene, and as such are promising candidates for both academic and industrial considerations

Ethyleneglycol tungsten complexes of calix[6 and 8]arenes: Synthesis, characterization and ROP of ε-caprolactone

By varying the reaction conditions, the reaction of [W(eg)₃] (eg = 1,2-ethanediolato) with p-tert-butylcalix[n]areneHn (n = 6 or 8) in refluxing toluene affords, following work-up, a number of products which have been fully characterized. From the reaction of p-tert-butylcalix[6]areneH₆ with one or two equivalents of [W(eg)₃], only the oxo-bridged complex {[W(eg)]₂(μ-O)p-tert-butylcalix[6]arene} (1) could be isolated, whereas the use of four equivalents of [W(eg)₃], in the presence of molecular sieves, afforded {[W(eg)₂]₂p-tert-butylcalix[6]areneH₂}·2MeCN (2); molecules of 2 pack in bi-layers. Under similar conditions, use of one or two equivalents of [W(eg)₃] and p-tert-butylcalix[8]areneH₈ afforded {[W(eg)]₂p-tert-butylcalix[8]arene}·MeCN (3) in which each tungsten centre was bound by four calixarene oxygens. By contrast, the small orange prisms resulting from the use of four equivalents of [W(eg)₃] and p-tert-butylcalix[8]areneH₈ were shown by synchrotron radiation to be a mixture of two isomers (4a/4b·3.5MeCN). In the major isomer {1,2-[W(eg)₂]₂p-tert-butylcalix[8]areneH₄} (4a), two tungsten centres bind to neighbouring sets of phenolate oxygens, whereas in the minor isomer {1,3-[W(eg)₂]₂p-tert-butylcalix[8]areneH₄} (4b), there is a protonated phenolic group between the two pairs of phenolate oxygens bound to tungsten; the major:minor ratio is about 83:17. Use of p-tert-butyltetrahomodioxacalix[6]areneH₆ with two equivalents of [W(eg)₃] resulted in the isolation of {[WO(eg)]₂p-tert-butyltetrahomodioxacalix[6]areneH₂} (5·0.83toluene·MeCN), in which each dimethyleneoxa bridge is bound to an oxotungsten(VI) centre. Complexes 1–5, together with the known complex [W(eg)p-tert-butylcalix[4]arene] (6), have been screened for their ability to ring open polymerize (ROP) ε-caprolactone; for 1, 2 and 5, 6 conversion rates were good (>88%) at 110 °C over 12 or 24 h, whereas the calix[8]arene complexes 3 and 4 under the same conditions were inactive

A convenient tandem one-pot synthesis of donor-acceptor-type triphenylene 2,3-dicarboxylic esters from diarylacetylene

A tandem one-pot method for the direct synthesis of polysubstituted triphenylene 2,3-dicarboxylic esters with different substitution patterns was developed by enyne metathesis of diarylacetylene, followed by Diels–Alder, aromatization and a cyclization cascade

Dconformer: A denoising convolutional transformer with joint learning strategy for intelligent diagnosis of bearing faults

Rolling bearings are the core components of rotating machinery, and their normal operation is crucial to entire industrial applications. Most existing condition monitoring methods have been devoted to extracting discriminative features from vibration signals that reflect bearing health status. However, the complex working conditions of rolling bearings often make the fault-related information easily buried in noise and other interference. Therefore, it is challenging for existing approaches to extract sufficient critical features in these scenarios. To address this issue, this paper proposes a novel CNN-Transformer network, referred to as Dconformer, capable of extracting both local and global discriminative features from noisy vibration signals. The main contributions of this research include: (1) Developing a novel joint-learning strategy that simultaneously enhances the performance of signal denoising and fault diagnosis, leading to robust and accurate diagnostic results; (2) Constructing a novel CNN-transformer network with a multi-branch cross-cascaded architecture, which inherits the strengths of CNNs and transformers and demonstrates superior anti-interference capability. Extensive experimental results reveal that the proposed Dconformer outperforms five state-of-the-art approaches, particularly in strong noisy scenarios

Fascin-1 and Digestive System Carcinoma

Invasion and metastasis are major reason for poor prognosis of digestive system carcinoma patients. Motility and migratory capacity are important in contributing to tumor cells’ invasion and metastasis. Fascin is one of actin cross-linking proteins and can participate in forming parallel actin bundles in cell protrusions. Fascin-1 is consequently involved in cell adhesion, motility, and signaling. In cultured cells, over-expression of fascin-1 can increase migration and invasion capacity of cells. Many studies show up-expressions of fascin-1 are significantly associated with worse prognosis, poor differentiation, TNM stage, positive for lymph node metastasis, and positive for distant metastasis in digestive system carcinoma patients. So fascin-1 may have prognostic value as an early biomarker for more aggressive digestive system carcinoma. This review provides detailed account of preclinical studies conducted to determine the utility of fascin-1 as a therapeutic and predictive agent in invasion and metastasis of carcinomas

Testing the Bell Inequality at Experiments of High Energy Physics

Besides using the laser beam, it is very tempting to directly testify the Bell inequality at high energy experiments where the spin correlation is exactly what the original Bell inequality investigates. In this work, we follow the proposal raised in literature and use the successive decays $J/\psi\to\gamma\eta_c\to \Lambda\bar\Lambda\to p\pi^-\bar p\pi^+$ to testify the Bell inequality. Our goal is twofold, namely, we first make a Monte-Carlo simulation of the processes based on the quantum field theory (QFT). Since the underlying theory is QFT, it implies that we pre-admit the validity of quantum picture. Even though the QFT is true, we need to find how big the database should be, so that we can clearly show deviations of the correlation from the Bell inequality determined by the local hidden variable theory. There have been some critiques on the proposed method, so in the second part, we suggest some improvements which may help to remedy the ambiguities indicated by the critiques. It may be realized at an updated facility of high energy physics, such as BES III.Comment: 16 pages, 5 figure

Coumarins from the Herb Cnidium monnieri and Chemically Modified Derivatives as Antifoulants against Balanus albicostatus and Bugula neritina Larvae

In the search for new environmental friendly antifouling (AF) agents, four coumarins were isolated from the herbal plant Cnidium monnieri, known as osthole (1), imperatorin (2), isopimpinellin (3) and auraptenol (4). Furthermore, five coumarin derivatives, namely 8-epoxypentylcoumarin (5), meranzin hydrate (6), 2'-deoxymetranzin hydrate (7), 8-methylbutenalcoumarin (8), and micromarin-F (9) were synthesized from osthole. Compounds 1, 2, 4, 7 showed high inhibitory activities against larval settlement of Balanus albicostatus with EC50 values of 4.64, 3.39, 3.38, 4.67 mu g mL(-1). Compound 8 could significantly inhibit larval settlement of Bugula neritina with an EC50 value of 3.87 mu g mL(-1). The impact of functional groups on anti-larval settlement activities suggested that the groups on C-5' and C-2'/C-3' of isoamylene chian could affect the AF activities

Identification of miRNAs and their target genes in developing soybean seeds by deep sequencing

<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) regulate gene expression by mediating gene silencing at transcriptional and post-transcriptional levels in higher plants. miRNAs and related target genes have been widely studied in model plants such as <it>Arabidopsis </it>and rice; however, the number of identified miRNAs in soybean (<it>Glycine max</it>) is limited, and global identification of the related miRNA targets has not been reported in previous research.</p> <p>Results</p> <p>In our study, a small RNA library and a degradome library were constructed from developing soybean seeds for deep sequencing. We identified 26 new miRNAs in soybean by bioinformatic analysis and further confirmed their expression by stem-loop RT-PCR. The miRNA star sequences of 38 known miRNAs and 8 new miRNAs were also discovered, providing additional evidence for the existence of miRNAs. Through degradome sequencing, 145 and 25 genes were identified as targets of annotated miRNAs and new miRNAs, respectively. GO analysis indicated that many of the identified miRNA targets may function in soybean seed development. Additionally, a soybean homolog of Arabidopsis SUPPRESSOR OF GENE SLIENCING 3 (<it>AtSGS3</it>) was detected as a target of the newly identified miRNA Soy_25, suggesting the presence of feedback control of miRNA biogenesis.</p> <p>Conclusions</p> <p>We have identified large numbers of miRNAs and their related target genes through deep sequencing of a small RNA library and a degradome library. Our study provides more information about the regulatory network of miRNAs in soybean and advances our understanding of miRNA functions during seed development.</p