Valence-State Effect of Iridium Dopant in NiFe(OH)2 Catalyst for Hydrogen Evolution Reaction.

Engineering high-performance electrocatalysts is of great importance for energy conversion and storage. As an efficient strategy, element doping has long been adopted to improve catalytic activity, however, it has not been clarified how the valence state of dopant affects the catalytic mechanism and properties. Herein, it is reported that the valence state of a doping element plays a crucial role in improving catalytic performance. Specifically, in the case of iridium doped nickel-iron layer double hydroxide (NiFe-LDH), trivalent iridium ions (Ir3+ ) can boost hydrogen evolution reaction (HER) more efficiently than tetravalent iridium (Ir4+ ) ions. Ir3+ -doped NiFe-LDH delivers an ultralow overpotential (19 mV @ 10 mA cm-2 ) for HER, which is superior to Ir4+ doped NiFe-LDH (44 mV@10 mA cm-2 ) and even commercial Pt/C catalyst (40 mV@ 10 mA cm-2 ), and reaches the highest level ever reported for NiFe-LDH-based catalysts. Theoretical and experimental analyses reveal that Ir3+ ions donate more electrons to their neighboring O atoms than Ir4+ ions, which facilitates the water dissociation and hydrogen desorption, eventually boosting HER. The same valence-state effect is found for Ru and Pt dopants in NiFe-LDH, implying that chemical valence state should be considered as a common factor in modulating catalytic performance.

Iodination/Amidation of the N-Alkyl (Iso)quinolinium Salts.

The NaIO4-mediated sequential iodination/amidation reaction of N-alkyl quinolinium iodide salts has been first developed. This cascade process provides an efficient way to rapidly synthesize 3-iodo-N-alkyl quinolinones with high regioselectivity and good functional group tolerance. This protocol was also amenable to the isoquinolinium salts, thus providing a complementary method for preparing the 4-iodo-N-alkyl isoquinolinones.

Palladium-Catalyzed Direct Arylation of Alkylpyridine via Activated N-Methylpyridinium Salts.

An efficient Pd-catalyzed arylation of alkylpyridine based on the pyridinium activation strategy has been developed for synthesis of mixed aryl alkylpyridines. It was found that (1) the N-methyl group in the pyridinium salts acted as a transient activator and could be automatically departed after the reaction, (2) CuBr was an indispensable additive for achieving the C6-selective arylation, (3) the α-branched alkyl chain on the alkylpyridine greatly increased the yield of the product. Deuterium labelling experiment revealed that in the case of the α-branched alkylpyridine, the presence of CuBr completely inhibited the H/D exchange at the benzylic position and thus enabled the selective arylation at the C6 position. This protocol demonstrates a broad substrate scope, and with respect to both the aryl iodides and the α-branched alkylpyridine, the desired mixed aryl alkylpyridines were obtained in generally good to excellent yields.

Research progress in RNA interference against the infection of mosquito-borne viruses.

Mosquito-borne diseases have become an important public health issue of global concern because of their high incidence and transmission rate. As a vector for mosquito-borne diseases, studying the interaction mechanism between mosquitoes and mosquito-borne viruses will help control mosquito-borne diseases. The impaired innate immunity and immune barriers evasion caused by mosquito-borne viruses in mosquitoes pose a potential risk for the persistent infection of the virus in mosquitoes and the outbreak of mosquito-borne diseases. The RNA interference (RNAi) pathway, as a powerful antiviral defense barrier in mosquitoes, can inhibit viral replication and transmission by producing a variety of small RNAs to degrade viral RNA. In this review, we summarize the related studies on the innate immune mechanism against mosquito- borne virus infection in mosquitoes about small interfering RNA (siRNA), microRNA (miRNA), and Piwi-interacting RNA (piRNA), aiming to provide a theoretical reference for the prevention and control of mosquito-borne diseases.

Electroreduction of Carbon Dioxide in Metallic Nanopores through a Pincer Mechanism.

Metallic catalysts with nanopores are advantageous on improving both activity and selectivity, while the reason behind that remains unclear all along. In this work, porous Zn nanoparticles (P-Zn) were adopted as a model catalyst to investigate the catalytic behavior of metallic nanopores. In situ X-ray absorption spectroscopy, in situ Fourier transform infrared spectroscopy, and density functional theory (DFT) analyses reveal that the concave surface of nanopores works like a pincer to capture and clamp CO2 and H2 O precursors simultaneously, thus lowering the energy barriers of CO2 electroreduction. Resultantly, the pincer mechanism endows P-Zn with a high Faradic efficiency (98.1 %) towards CO production at the potential of -0.95 V vs. RHE. Moreover, DFT calculation demonstrates that Co and Cu nanopores exhibit the pincer behavior as well, suggesting that this mechanism is universal for metallic nanopores.

Dehydrogenation of Alcohols to Carboxylic Acid Catalyzed by in Situ-Generated Facial Ruthenium-CPP Complex.

A selective catalytic system for the dehydrogenation of primary alcohols to carboxylic acids using a facial ruthenium complex generated in situ from the [Ru(COD)Cl2]n and a hybrid N-heterocyclic carbene (NHC)-phosphine-phosphine ligand (CPP) has been first reported. The facial coordination model was unveiled by NMR analysis of the reaction mixture. Such a fac-ruthenium catalyst system exhibited high catalytic activity and stability, and a high turnover number of 20 000 could be achieved with catalyst loading as low as 0.002 mol %. The exceedingly high catalyst stability was tentatively attributed to both the anchoring role of NHC and the hemi-lability of phosphines. The catalytic system also features a wide substrate scope. In particular, the facial coordination of CPP ligands was found to be beneficial for sterically hindered alcohols, and ortho-substituted benzylic alcohols and bulky adamantanyl methanol as well as cholesterol were all found to be viable dehydrogenation substrates.

Iridium-Catalyzed Alkylation of Amine and Nitrobenzene with Alcohol to Tertiary Amine under Base- and Solvent-Free Conditions.

Herein, an efficient and green method for the selective synthesis of tertiary amines has been developed that involves iridium-catalyzed alkylation of various primary amines with aromatic or aliphatic alcohols. Notably, the catalytic protocol enables this transformation in the absence of additional base and solvent. Furthermore, the alkylation of nitrobenzene with primary alcohol to tertiary amine has also been achieved by the same catalytic system. Deuterium-labeling experiments and a series of control experiments were conducted, and the results suggested that an intermolecular borrowing hydrogen pathway might exist in the alkylation process.

Palladium-Catalyzed Domino Reaction for Stereoselective Synthesis of Multisubstituted Olefins: Construction of Blue Luminogens.

The first Pd-catalyzed multicomponent reaction of aryl iodides, alkenyl bromides, and strained alkenes has been developed, which allowed us to synthesize a variety of multisubsituted olefins in yields of 45-96% with excellent stereoselectivity. The configuration of the product was controlled by the configuration of the alkenyl bromides. Moreover, this practical methodology employing readily available substrates was found to be tolerant to a wide range of functional groups. Fifty six examples of highly stereoselective tri- or tetrasubstituted olefins have been successfully synthesized via this methodology. Most of the synthesized tetrasubstituted olefins are good aggregation-induced emission (AIE) luminogens.

Modest Oxygen-Defective Amorphous Manganese-Based Nanoparticle Mullite with Superior Overall Electrocatalytic Performance for Oxygen Reduction Reaction.

Manganese-based oxides have exhibited high promise as noncoinage alternatives to Pt/C for catalyzing oxygen reduction reaction (ORR) in basic solution and a mix of Mn3+/4+ valence is believed to be vital in achieving optimum ORR performance. Here, it is proposed that, distinct from the most studied perovskites and spinels, Mn-based mullites with equivalent molar ratio of Mn3+ and Mn4+ provide a unique platform to maximize the role of Mn valence in facile ORR kinetics by introducing modest content of oxygen deficiency, which is also beneficial to enhanced catalytic activity. Accordingly, amorphous mullite SmMn2 O5-δ nanoparticles with finely tuned concentration of oxygen vacancies are synthesized via a versatile top-down approach and the modest oxygen-defective sample with an Mn3+ /Mn4+ ratio of 1.78, i.e., Mn valence of 3.36 gives rise to a superior overall ORR activity among the highest reported for the family of Mn-based oxides, comparable to that of Pt/C. Altogether, this study opens up great opportunities for mullite-based catalysts to be a cost-effective alternative to Pt/C in diverse electrochemical energy storage and conversion systems.

An Approach to the Synthesis of 1-Propenylnaphthols and 3-Arylnaphtho[2,1-b]furans.

A simple and efficient strategy for the synthesis of 1-propenylnaphthols from readily accessible 3-arylallylnaphthyl ethers has been developed. By using K2CO3 as base and 2-methoxyethanol as solvent, direct access to a wide range of 1-propenylnaphthols can be achieved in generally good yield (up to 99%) with high stereoselectivity toward the Z isomer. The control experiments indicate that the reaction proceeds through a sequential Claisen rearrangement/isomerization process. Furthermore, starting from the same material, the highly valuable 3-arylnaphtho[2,1-b]furans can be obtained in N,N-dimethylformamide and in the presence of Ag2O as the oxidant via a one-pot sequential Claisen rearrangement/isomerization/cyclization reaction. Mechanistic studies confirm that 1-propenylnaphthols are the key intermediates to form the 3-arylnaphtho[2,1-b]furans. In addition, these two operationally simple and practical protocols could be scaled up to a gram level.

An Additive Effect of Promoting Thermogenic Gene Expression in Mice Adipose-Derived Stromal Vascular Cells by Combination of Rosiglitazone and CL316,243.

It is well-documented that CL316,243 (a ß3 agonist) or rosiglitazone (a PPARγ agonist) can induce white adipocyte populations to brown-like adipocytes, thus increasing energy consumption and combating obesity. However, whether there is a combined effect remains unknown. In the present study, stromal vascular cells of inguinal white adipose tissue (iWAT-SVCs for short) from mice were cultured and induced into browning by CL316,243, rosiglitazone, or both. Results showed that a combination of CL316,243 and rosiglitazone significantly upregulated the expression of the core thermogenic gene Ucp1 as well as genes related with mitochondrial function (Cidea, Cox5b, Cox7a1, Cox8b, and Cycs), compared with the treatment of CL316,243 or rosiglitazone alone. Moreover, co-treatment with rosiglitazone could reverse the downregulation of Adiponectin resulting from CL316,243 stimuli alone. Taken together, a combination of rosiglitazone and CL316,243 can produce an additive effect of promoting thermogenic gene expression and an improvement of insulin sensitivity in mouse iWAT-SVCs.

[Research progress on application of DNA barcoding technique in Culicidae taxonomy].

DNA barcoding technique is a fast and accurate method for species identification. The DNA barcoding based on cytochrome c oxidase subunit Ⅰ (COⅠ) has recently been successfully applied for species identification of Culicidae. In this paper, we introduce the technique and principle of DNA barcoding, application and limitation of the technique based on CO I gene for species identification, as well as research development on applications of other molecular makers such as COⅡ,16S RNA, and the first and the second internal transcribed spacers (ITS1 and ITS2) in species identification and to assist the COⅠ gene in identifying Culicidae species.

ZnFe2 O4 Leaves Grown on TiO2 Trees Enhance Photoelectrochemical Water Splitting.

TiO2 has excellent electrochemical properties but limited solar photocatalytic performance in light of its large bandgap. One important class of visible-wavelength sensitizers of TiO2 is based on ZnFe2 O4 , which has shown fully a doubling in performance relative to pure TiO2 . Prior efforts on this important front have relied on presynthesized nanoparticles of ZnFe2 O4 adsorbed on a TiO2 support; however, these have not yet achieved the full potential of this system since they do not provide a consistently maximized area of the charge-separating heterointerface per volume of sensitizing absorber. A novel atomic layer deposition (ALD)-enhanced synthesis of sensitizing ZnFe2 O4 leaves grown on the trunks of TiO2 trees is reported. These new materials exhibit fully a threefold enhancement in photoelectrochemical performance in water splitting compared to pristine TiO2 under visible illumination. The new materials synthesis strategy relies first on the selective growth of FeOOH nanosheets, 2D structures that shoot off from the sides of the TiO2 trees; these templates are then converted to ZnFe2 O4 with the aid of a novel ALD step, a strategy that preserves morphology while adding the Zn cation to achieve enhanced optical absorption and optimize the heterointerface band alignment.

CTSB promotes porcine preadipocytes differentiation by degrading fibronectin and attenuating the Wnt/ß-catenin signaling pathway.

The process of preadipocytes differentiation plays a vital role in adipose tissue expansion and many factors are involved in this event. Cathepsin B (CTSB), secreted from lysosome, has been reported in regulating a variety of physiological processes. In this study, we demonstrated CTSB promotes lipid accumulation and adipogenic genes expression in porcine primary preadipocytes by degrading fibronectin (Fn), a key component of extracellular matrix. Lithium chloride (LiCl) is an activator of Wnt/ß-catenin signaling through stabilizing ß-catenin. We found that CTSB can relieve the anti-adipogenic effects of LiCl, indicating that CTSB could impact Wnt/ß-catenin signaling pathway. Interestingly, Fn is an important target gene of Wnt/ß-catenin. So we considered that CTSB promote preadipocytes differentiation by suppressing these two pathways.

miR-125a inhibits porcine preadipocytes differentiation by targeting ERRα.

MicroRNAs are a family of small, non-coding RNAs that regulate gene expression in a sequence-specific manner. Estrogen-related receptor α (ERRα) is an orphan nuclear receptor which plays an important role in adipocyte differentiation. Our previous Solexa sequencing results indicated a high expression of miR-125a in adult pig backfat. In this study, we predicated and experimentally validated ERRα as a target of miR-125a. To explore the role of miR-125a in porcine preadipocytes differentiation, miRNA agomir and antagomir were used to perform miR-125a overexpression or knockdown, respectively. Our results showed that overexpression of miR-125a could dramatically reduce the mRNA expression of adipogenic markers PPARγ, LPL, and aP2, as well as its target gene ERRα. Western blotting showed the protein level of aP2 and ERRα was also significantly down-regulated. The overexpression of miR-125a also led to a notable reduction in lipid accumulation which was detected by Oil Red O staining. In contrast, we observed promoted differentiation of porcine preadipocytes upon miR-125a inhibition. In conclusion, we verified miR-125a inhibits porcine preadipocytes differentiation through targeting ERRα for the first time, which may provide new insights in pork quality improvement and obesity control.

Copper-Mediated and Palladium-Catalyzed Cross-Coupling of Indoles and N-Methylpyridinium Salts: A Practical Way to Prepare 3-(Pyridin-2-yl)indoles.

Herein, a Pd/Cu bimetallic-catalyzed direct C-H heteroarylation of pyridines via the traceless protecting group strategy is described. A series of N-methyl-activated pyridines and 1-methylindoles are coupled with high regioselectivity to produce the corresponding 3-(pyridin-2-yl)indoles in moderate to good yields, wherein related electron-rich heterocycles (e.g., indole, 1-methylpyrrole, benzofuran, benzo[b]thiophene) are also applicable. Streamlined operation, good functional group tolerance, and late-stage modifications make this twofold C-H activation protocol an attractive route for the synthesis of 3-(pyridin-2-yl)indole derivatives.

[Cloning of AGO2 and Dcr-2 gene fragments and analysis of their transcription level in different developmental stages of Aedes albopictus].

OBJECTIVE: To perform molecular cloning of the AGO2 and Dcr-2 gene fragments associated with RNA interference pathway of Aedes albopictus and characterize the transcription level of the two genes across all life stages of the mosquito. METHODS: The degenerate primers were designed based on the conserved regions of AGO2 and Dcr-2 amino acid sequences, and the AGO2 and Dcr-2 cDNA fragments were amplified from total RNA of a female mosquito by RT-PCR. The PCR products were cloned into pMD18-T vector and transformed into E. coli DH5alpha strain, and the positive clones were selected and sequenced, with the results for homology analysis by Blastx. The specific primers were designed according to the sequences of AGO2 and Dcr-2 from Ae. albopictus, which were used to investigate the transcription levels of these two genes from eggs, I and II instars larvae, III and IV instars larvae, pupa, male and female mosquitoes by semi-quantitative RT-PCR. RESULTS: The AGO2 and Dcr-2 cDNA fragments obtained were 326 bp and 491 bp in length, with the Accession number of JQ764670 and JQ764671, respectively. The Blastx analysis showed that the AGO2 and Dcr-2 amino acid sequences shared 91% similarity to AGO2 of Ae. aegypti and 98% to Dcr-2 of Ae. albopictus. The transcription of AGO2 and Dcr-2 genes was detected in all life stages of Ae. albopictus, with the highest level of mRNA in female mosquitoes, which was 3.1 times and 15.5 times higher for AGO2 and Dcr-2 than in male mosquitoes, respectively, and significantly higher than other developmental stages (P<0.05). CONCLUSION: The AGO2 and Dcr-2 cDNA sequences have been partially obtained and the highest transcription level found in female Ae. albopictus, suggesting that AGO2 and Dcr-2 are the key genes of RNA interference in female mosquitoes.

The Zinc Finger Transcription Factor BbCmr1 Regulates Conidium Maturation in Beauveria bassiana.

The entomopathogenic fungus Beauveria bassiana is a typical filamentous fungus and has been used for pest biocontrol. Conidia are the main active agents of fungal pesticides; however, we know little about conidial developmental mechanisms and less about maturation mechanisms. We found that a Zn2Cys6 transcription factor of B. bassiana (named BbCmr1) was mainly expressed in late-stage conidia and was involved in conidium maturation regulation. Deletion of Bbcmr1 impaired the conidial cell wall and resulted in a lower conidial germination rate under UV (UV), heat shock, H2O2, Congo red (CR) and SDS stresses compared to the wild type. Transcription levels of the genes associated with conidial wall components and trehalose synthase were significantly reduced in the ΔBbcmr1 mutant. Further analysis found that BbCmr1 functions by upregulating BbWetA, a well-known transcription factor in the central development of BrlA-AbaA-WetA. The expression of Bbcmr1 was positively regulated by BbBrlA. These results indicated that BbCmr1 played important roles in conidium maturation by interacting with the central development pathway, which provided insight into the conidial development networks in B. bassiana. IMPORTANCE Conidium maturation is a pivotal event in conidial development and affects fungal survival ability under various biotic/abiotic stresses. Although many transcription factors have been reported to regulate conidial development, we know little about the molecular mechanism of conidium maturation. Here, we demonstrated that the transcription factor BbCmr1 of B. bassiana was involved in conidium maturation, regulating cell wall structure, the expression of cell wall-related proteins, and trehalose synthesis. BbCmr1 orchestrated conidium maturation by interplaying with the central development pathway BrlA-AbaA-WetA. BbBrlA positively regulated the expression of Bbcmr1, and the latter positively regulated BbwetA expression, which forms a regulatory network mediating conidial development. This finding was critical to understand the molecular regulatory networks of conidial development in B. bassiana and provided avenues to engineer insect fungal pathogens with high-quality conidia.

Electrochemical Cross-Dehydrogenative Aromatization Protocol for the Synthesis of Aromatic Amines.

The introduction of amines onto aromatics without metal catalysts and chemical oxidants is synthetically challenging. Herein, we report the first example of an electrochemical cross-dehydrogenative aromatization (ECDA) reaction of saturated cyclohexanones and amines to construct anilines without additional metal catalysts and chemical oxidants. This reaction exhibits a broad scope of cyclohexanones including heterocyclic ketones, affording a variety of aromatic amines with various functionalities, and shows great potential in the synthesis of biologically active compounds.