Heteroatom-Modulated Assembly of Hexalanthanoid-Containing Polyoxometalate-Based Coordination Networks.

Two series of lanthanoid (Ln)-containing polyoxometalates (POMs) {[Ln6(ampH)4(H2O)24-n(ampH2)n(PW11O39)2]·21H2O (Ln = Tb, n = 0 (1), Ln = Er, n = 1 (2)) and K2[Ln6(ampH)4(H2O)22(SiW11O39)2]·23H2O (Ln = Tb (3), Er (4)) (ampH2 = (aminomethyl) phosphonic acid)} have been synthesized with tri-lacunary Keggin-type POMs containing different types of heteroatoms. Compounds 1 and 2 display neutral organic-inorganic hybrid POM molecules containing {Ln6(ampH)4} ({Ln6}) cores sandwiched by two {PW11O39} units. By changing the heteroatoms from PV to SiIV, the extended 2D networks of 3 and 4 were successfully isolated where the adjacent {Ln6} clusters were connected by {SiW11O39} moieties. Luminescence performances and magnetic properties of 1-4 have been systematically surveyed. The solid-state fluorescence spectra of 1-4 display characteristic emissions of Ln components resulting from the 4f-4f transitions, and energy transfer from the POM segments to Ln3+ centers in 1 and 3 has been observed based on the lifetime decay behaviors. Furthermore, all compounds can be utilized as electrocatalysts toward reduction of nitrite with high stability.

One-Week-Ahead Prediction of Cyanobacterial Harmful Algal Blooms in Iowa Lakes.

Cyanobacterial harmful algal blooms (CyanoHABs) pose serious risks to inland water resources. Despite advancements in our understanding of associated environmental factors and modeling efforts, predicting CyanoHABs remains challenging. Leveraging an integrated water quality data collection effort in Iowa lakes, this study aimed to identify factors associated with hazardous microcystin levels and develop one-week-ahead predictive classification models. Using water samples from 38 Iowa lakes collected between 2018 and 2021, feature selection was conducted considering both linear and nonlinear properties. Subsequently, we developed three model types (Neural Network, XGBoost, and Logistic Regression) with different sampling strategies using the nine selected variables (mcyA_M, TKN, % hay/pasture, pH, mcyA_M:16S, % developed, DOC, dewpoint temperature, and ortho-P). Evaluation metrics demonstrated the strong performance of the Neural Network with oversampling (ROC-AUC 0.940, accuracy 0.861, sensitivity 0.857, specificity 0.857, LR+ 5.993, and 1/LR- 5.993), as well as the XGBoost with downsampling (ROC-AUC 0.944, accuracy 0.831, sensitivity 0.928, specificity 0.833, LR+ 5.557, and 1/LR- 11.569). This study exhibited the intricacies of modeling with limited data and class imbalances, underscoring the importance of continuous monitoring and data collection to improve predictive accuracy. Also, the methodologies employed can serve as meaningful references for researchers tackling similar challenges in diverse environments.

Corrosion Behavior of Nitrogen-Containing Low-Nickel Weld Cladding in KCl-MgCl2 Eutectic Molten Salt at 900 °C.

In this paper, the element nitrogen (N) is used to partially replace the element nickel (Ni) in flux-cored wire. A 44%Ni-24%Cr-0.18N nitrogen-containing low-nickel flux-cored wire with excellent corrosion resistance is prepared. The corrosion behavior of nitrogen-containing low-nickel weld cladding and Inconel 625 weld cladding in 40 KCl + 60 MgCl2 (wt%) molten salt at 900 °C is studied. The results show that the selective dissolution of Cr occurs in both weld claddings. The corrosion resistance of the 44%Ni-24%Cr-0.18N nitrogen-containing low-nickel weld cladding is better than that of the Inconel 625 weld cladding. The reason is that added N can react with H+ in molten salt to generate NH4+, remove corrosive impurities of MgOH+ in molten salt and change the corrosion environment. N preferentially combines with Cr to form Cr2N, reduces the diffusion precipitation of Cr and improves the corrosion resistance.

Up-regulation of caveolin 1 mediated by chitosan activates Wnt/ ß-catenin pathway in chronic refractory wound diabetic rat model.

Diabetes mellitus (DM) can be implicated in the perturbations of vascular integrity and the dysfunction of angiogenesis. Chitosan has the advantage of promoting the vascular endothelial cell proliferation. However, the molecular mechanism of action in the promotion of wound healing by chitosan derivatives is still debated. In the current study, DM with chronic wound (CW) model rats were prepared and treated with chitosan. Vascular endothelial cells isolated from granulation tissues were conducted by RNA sequencing. Two thousand three hundred and sixteen genes were up-regulated, while 1,864 genes were down-regulated after chitosan treatment compared to CW group. Here, we observed that caveolin 1 (CAV1) was highly expressed induced by chitosan. Furthermore, we observed that CAV1 knockdown could compromise the activation of Wnt pathway by reduction of ß-catenin in rat aortic endothelial cells (RAOECs) and brain endothelium four cells (RBE4s). Moreover, we determined a direct interaction between CAV1 and ß-catenin by IP assay. The C-terminus of CAV1 and ß-catenin (24 to 586 amino acids) contributed to the interaction of these two proteins. Finally, the protein docking analysis indicated that the fragments of ß-catenin (253-261 'FYAITTLHN' and 292-303 'KFLAITTDCLQI') might have affected the structure by CAV1 and facilitated the resistance to degradation. Taken together, our study demonstrates that chitosan can up-regulate CAV1 expression, and CAV1 can interact with ß-catenin for promotion of canonical Wnt signaling pathway activity. Our results deepens the molecular mechanism of the Wnt pathway in vascular endothelial cells and is beneficial to developing new targets to assist in enhancing the pharmacological effect of chitosan on wound healing and angiogenesis against DM.

Improved detection of mcyA genes and their phylogenetic origins in harmful algal blooms.

Microcystins, a group of cyanotoxins produced by cyanobacterial strains, have become a significant microbial hazard to human and animal health due to increases in the frequency and intensity of cyanobacterial harmful algal blooms (CyanoHABs). Many studies have explored the correlation between microcystin concentrations and abundances of toxin-producing genes (e.g., mcyA genes) measured using quantitative PCR, and discrepancies between toxin concentrations and gene abundances are often observed. In this study, the results show that these discrepancies are at least partially due to primer sets that do not capture the phylogenetic diversity of naturally present toxin-producers. We designed three novel primer gene probes based on known mcyA genes to improve the detection and quantification of these genes in environmental samples. These primers were shown to improve the identification of mcyA genes compared to previously published primers in freshwater metagenomes, cyanobacterial isolates, and lake water samples. Unlike previously published primers, our primer sets could selectively amplify and resolve Microcystis, Anabaena, and Planktothrix mcyA genes. In lake water samples, abundance estimations of mcyA genes were found to correlate strongly with microcystin concentrations. Based on our results, these primers offer significant improvements over previously published probes to accurately identify and quantify mcyA genes in the environment. There is an increasing need to develop models based on microbial information and environmental factors to predict CyanoHABs, and improved primers will play an important role in aiding monitoring efforts to collect reliable and consistent data on toxicity risks.

[Genetic characteristics of HIV-1 primary drug resistance-associated mutations in treatment-naive individuals in Liaoning province, 2004-2008].

OBJECTIVE: To investigate the HIV-1 drug resistance associated mutations and examine the susceptibility of HIV-1 with these mutations to antiretroviral in treatment-naive individuals in Liaoning province from 2004 to 2008. METHODS: RNA was extracted from 20 plasma samples of diagnosed untreated HIV-1-infected treatment-naive patients by drawing method. After the viral loading (VL) test, the protease and nucleoside reverse transcriptase coding regions were amplified by RT-PCR, nested PCR and sequence analysis directly. Levels of resistance and prevalence were evaluated according to the Stanford University HIV Drug Resistance Database's algorithm (http://hivdb.stanford.edu). RESULTS: Among the 20 plasma samples, 13 got PCR products because of their VL values higher than 1000 copies/ml.Meanwhile, the 13 samples got 65 sequences by using 5 primers each. Polymorphisms in subtype H and circulating recombinant forms (CRFs) CRF10_CD sequences were identified. An overall prevalence of 30.8% (4/13) resistance to NNRTIs, 7.7% (1/13) to PI and no NRTIs mutations were found. The most frequent substitutions (4/13) in the RT region at positions P225H, K238S, V179D, K238T and a major position I54S in PR implied to a multiple drug-resistance. A71V or L10V only, respectively, substitution in PR was found in 3 samples, but no any worse with drug sensitivity. CONCLUSION: HIV-1 polymorphisms in subtype H and CRFs CRF10_CD sequences were identified circulating in Liaoning. A major mutation position I54S in PR implied that it would be the time to commence a higher level drug regimen.

Highly selective palladium-catalyzed one-pot, five-fold B-H/C-H cross coupling of monocarboranes with alkenes.

Palladium-catalyzed dehydrogenative B-H/C-H cross coupling of monocarborane anions with alkenes is reported, allowing for the first time the isolation of selectively penta-alkenylated boron clusters. The reaction cascade is regioselective for the cage positions, leading directly to B2-6 functionalization. Under mild and convenient conditions, styrenes, benzylic alkenes and aliphatic alkenes are demonstrated to be viable coupling partners with exclusive vinyl-type B-C bond formation. Multiple subsequent transformations provide access to directing group-free products, chiral derivatives and penta-alkylated cages. The five-fold coupling, combined with the latter reactions, represents a powerful methodology for the straightforward synthesis of new classes of boron clusters.

Rhodium(iii)-catalyzed dehydrogenative dialkenylation of the monocarba-closo-decaborate cluster by regioselective B-H activation.

closo-Boranes and closo-carboranes, clusters with a closed-cage structure, exhibit remarkable inertness and are unique components of products with applications in areas such as medicinal chemistry, fluorescence and materials science. Herein, we report the first transition metal-catalyzed functionalization of the mono-closo-decaborate cluster [1-CB9H10]- by regioselective B-H activation. Using terminal alkenes bearing a wide range of functional groups, dehydrogenative coupling under mild conditions leads to B2/3-dialkenylated products, as verified by X-ray crystallography and NMR studies. This substitution pattern has not been accessible by other methods and enables the straightforward synthesis of new derivatives of the {CB9} cluster.

B-H functionalization of the monocarba-closo-dodecaborate anion by rhodium and iridium catalysis.

The regioselective derivatization of the monocarba-closo-dodecaborate anion via catalytic B-H bond activation is reported. Amide directing groups in combination with rhodium and iridium catalysts allowed for the direct functionalization of cage boron vertices. Products comprising B-C, B-N and B-Cl bonds were synthesized. As a key intermediate of the B-H activation step, an iridium complex with a direct B-Ir interaction was isolated and fully characterized by spectroscopic methods as well as X-ray crystallography.