Zika virus (ZIKV) has become a threat to global health since the outbreak in Brazil in 2015. Although ZIKV is generally considered an Aedes-transmitted pathogen, new evidence has shown that parts of ...the virus closely resemble Culex-transmitted viruses. Therefore, it is important to evaluate the competence of Culex species for ZIKV to understand their potential as vectors. In this study, female Culex pipiens quinquefasciatus were orally exposed to ZIKV. Mosquito midguts, salivary glands and ovaries were tested for ZIKV to measure infection and dissemination at 2, 4, 6, 8, 12, 16 and 18 days post exposure (pe). In addition, saliva was collected from mosquitoes after infection and infant mice were bitten by infected mosquitoes to measure the transmission ability of Cx. p. quinquefasciatus. The results showed that the peak time of virus appearance in the salivary glands was day 8 pe, with 90% infection rate and an estimated virus titer of 3.92±0.49 lg RNA copies/mL. Eight of the nine infant mice had positive brains after being bitten by infected mosquitoes, which meant that Cx. p. quinquefasciatus could be infected with and transmit ZIKV following oral infection. These laboratory results clearly demonstrate the potential role of Cx. p. quinquefasciatus as a vector of ZIKV in China. Because there are quite different vector management strategies required to control Aedes (Stegomyia) species and Cx. p. quinquefasciatus, an integrated approach may be required should a Zika epidemic occur.
A Concise Total Synthesis of (−)‐Berkelic Acid Cheng, Hong‐Gang; Yang, Zhenjie; Chen, Ruiming ...
Angewandte Chemie International Edition,
March 1, 2021, Letnik:
60, Številka:
10
Journal Article
Recenzirano
Reported here is a concise total synthesis of (−)‐berkelic acid in eight linear steps. This synthesis features a Catellani reaction/oxa‐Michael cascade for the construction of the isochroman ...scaffold, a one‐pot deprotection/spiroacetalization operation for the formation of the tetracyclic core structure, and a late‐stage Ni‐catalyzed reductive coupling for the introduction of the lateral chain. Notably, four stereocenters are established from a single existing chiral center with excellent stereocontrol during the deprotection/spiroacetalization process. Stereocontrol of the intriguing deprotection/spiroacetalization process is supported by DFT calculations.
A concise total synthesis of (−)‐berkelic acid in eight linear steps was developed. This synthesis features a Catellani reaction/oxa‐Michael cascade for the construction of the isochroman scaffold, a one‐pot deprotection/spiroacetalization operation for the formation of tetracyclic core structure, and a late‐stage Ni‐catalyzed reductive coupling for the introduction of the lateral chain.
Anopheles stephensi is native to Southeast Asia and the Arabian Peninsula and has emerged as an effective and invasive malaria vector. Since invasion was reported in Djibouti in 2012, the global ...invasion range of An. stephensi has been expanding, and its high adaptability to the environment and the ongoing development of drug resistance have created new challenges for malaria control. Climate change is an important factor affecting the distribution and transfer of species, and understanding the distribution of An. stephensi is an important part of malaria control measures, including vector control.
In this study, we collected existing distribution data for An. stephensi, and based on the SSP1-2.6 future climate data, we used the Biomod2 package in R Studio through the use of multiple different model methods such as maximum entropy models (MAXENT) and random forest (RF) in this study to map the predicted global An. stephensi climatically suitable areas.
According to the predictions of this study, some areas where there are no current records of An. stephensi, showed significant areas of climatically suitable for An. stephensi. In addition, the global climatically suitability areas for An. stephensi are expanding with global climate change, with some areas changing from unsuitable to suitable, suggesting a greater risk of invasion of An. stephensi in these areas, with the attendant possibility of a resurgence of malaria, as has been the case in Djibouti.
This study provides evidence for the possible invasion and expansion of An. stephensi and serves as a reference for the optimization of targeted monitoring and control strategies for this malaria vector in potential invasion risk areas.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Porous molecular crystals sustained by hydrogen bonds and/or weaker connections are an intriguing type of adsorbents, but they rarely demonstrate efficient adsorptive separation because of poor ...structural robustness and tailorability. Herein, we report a porous molecular crystal based on hydrogen‐bonded cyclic dinuclear AgI complex, which exhibits exceptional hydrophobicity with a water contact angle of 134°, and high chemical stability in water at pH 2–13. The seemingly rigid adsorbent shows a pore‐opening or nonporous‐to‐porous type butane adsorption isotherm and complete exclusion of isobutane, indicating potential molecular sieving. Quantitative column breakthrough experiments show slight co‐adsorption of isobutane with an experimental butane/isobutane selectivity of 23, and isobutane can be purified more efficiently than for butane. In situ powder/single‐crystal X‐ray diffraction and computational simulations reveal that a trivial guest‐induced structural transformation plays a critical role.
A rigid hydrogen‐bonded porous molecular crystal shows not only exceptionally high hydrophobicity and chemical stability, but also molecular‐sieving‐like separation of butane/isobutane associated with a trivial guest‐induced structural transformation revealed by powder/single‐crystal X‐ray diffraction and computational simulations.
Electrolyte additive is an effective strategy to inhibit the uncontrolled growth of Li dendrites for lithium metal batteries (LMBs). However, most of the additives are complex synthesis and prone to ...decompose in cycling. Herein, in order to guide the homogeneous deposition of Li+, carbonized polymer dots (CPDs) as electrolyte additives are successfully designed and synthesized by microwave (M‐CPDs) and hydrothermal (H‐CPDs) approaches. The controllable functional groups containing N or O (especially pyridinic‐N, pyrrolic‐N, and carboxyl group) enable CPDs to keep stable in electrolytes for at least 3 months. Meanwhile, the clusters formed between CPDs and Li+ through electrostatic interaction effectively guide the uniform Li dispersion and limit the “tip effect” and dendrite formation. Moreover, as lithiophilic groups increase, the strong electrostatic interference for the solvation effect of Li+ in the electrolyte is formed, which induces faster Li+ diffusion/transfer. As expected, H‐CPDs achieve the ultra‐even Li+ transfer. The corresponding Li//LiFePO4 full cell delivers a high capacity retention rate of 93.8% after 200 cycles, which is much higher than that of the cells without additives (61.2%) and with M‐CPDs (83.7%) as additives. The strategy in this work provides a theoretical direction for CPDs as electrolyte additives used in energy storage devices.
Two kinds of carbonized polymer dots (CPDs) (M‐CPDs and H‐CPDs) as electrolyte additives are successfully designed and synthesized. H‐CPDs with more pyridinic‐N, pyrrolic‐N, and COOH deliver more even Li+ flux through abundant H‐CPDs‐Li clusters bound by strong electrostatic interaction. The symmetrical cell exhibits enhanced cycling stability of 3700 h.
Increased glucose production and reduced hepatic glycogen storage contribute to metabolic abnormalities in diabetes. Irisin, a newly identified myokine, induces the browning of white adipose tissue, ...but its effects on gluconeogenesis and glycogenesis are unknown. In the present study, we investigated the effects and underlying mechanisms of irisin on gluconeogenesis and glycogenesis in hepatocytes with insulin resistance, and its therapeutic role in type 2 diabetic mice. Insulin resistance was induced by glucosamine (GlcN) or palmitate in human hepatocellular carcinoma (HepG2) cells and mouse primary hepatocytes. Type 2 diabetes was induced by streptozotocin/high-fat diet (STZ/HFD) in mice. In HepG2 cells, irisin ameliorated the GlcN-induced increases in glucose production, phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) expression, and glycogen synthase (GS) phosphorylation; it prevented GlcN-induced decreases in glycogen content and the phosphoinositide 3-kinase (PI3K) p110α subunit level, and the phosphorylation of Akt/protein kinase B, forkhead box transcription factor O1 (FOXO1) and glycogen synthase kinase-3 (GSK3). These effects of irisin were abolished by the inhibition of PI3K or Akt. The effects of irisin were confirmed in mouse primary hepatocytes with GlcN-induced insulin resistance and in human HepG2 cells with palmitate-induced insulin resistance. In diabetic mice, persistent subcutaneous perfusion of irisin improved the insulin sensitivity, reduced fasting blood glucose, increased GSK3 and Akt phosphorylation, glycogen content and irisin level, and suppressed GS phosphorylation and PEPCK and G6Pase expression in the liver. Irisin improves glucose homoeostasis by reducing gluconeogenesis via PI3K/Akt/FOXO1-mediated PEPCK and G6Pase down-regulation and increasing glycogenesis via PI3K/Akt/GSK3-mediated GS activation. Irisin may be regarded as a novel therapeutic strategy for insulin resistance and type 2 diabetes.
Many concerns have been raised about ecological and environmental risks from the disposal of red mud (RM) in the aluminium industry. For a long time a suitable use for RM, due to the huge amount ...produced, has been needed. This study, for the first time, applies RM as an efficient electrochemical catalyst in the emerging nitrate-to-ammonia reduction reaction (NARR) based on renewable energy, in which the produced green ammonia can supply energy for rechargeable ammonia energy storage (RAES). The performance of RM stands out among many other synthetic catalysts in the NARR as well as further combination with photovoltaic technology. Specifically, it exhibits a superior faradaic efficiency toward NH
3
of 92.8% and an NH
3
formation rate of 0.16 mmol cm
−2
h
−1
under −0.73 V (
vs
. reversible hydrogen electrode) in a neutral phosphate buffer solution with 1.0 M NO
3
−
. The energy efficiency toward NH
3
is over 30% in a two-electrode system, and that of the solar-to-NH
3
conversion is 2.09% at a light intensity of 0.06 W cm
−2
based on a commercial poly-Si photovoltaic cell. The results promise a low-cost RM catalyst for the NARR sustainable route, realizing RM recycling and zero-carbon ammonia-energy production.
A sustainable red mud disposal solution is proposed based on the emerging electrocatalytic nitrate-to-ammonia reduction reaction, exhibiting outstanding performance and efficient energy conversion compared to many other synthetic catalysts.
We present a detailed DFT mechanistic study on the first Ni-catalyzed direct carbonyl-Heck coupling of aryl triflates and aldehydes to afford ketones. The precatalyst Ni(COD)
2
is activated with the ...phosphine (phos) ligand, followed by coordination of the substrate PhOTf, to form Ni(phos)(PhOTf) for intramolecular PhOTf to Ni(0) oxidative addition. The ensuing phenyl-Ni(
ii
) triflate complex substitutes benzaldehyde for triflate by an interchange mechanism, leaving the triflate anion in the second coordination sphere held by Coulomb attraction. The Ni(
ii
) complex cation undergoes benzaldehyde C&z.dbd;O insertion into the Ni-Ph bond, followed by β-hydride elimination, to produce Ni(
ii
)-bound benzophenone, which is released by interchange with triflate. The resulting neutral Ni(
ii
) hydride complex leads to regeneration of the active catalyst following base-mediated deprotonation/reduction. The benzaldehyde C&z.dbd;O insertion is the rate-determining step. The triflate anion, while remaining in the second sphere, engages in electrostatic interactions with the first sphere, thereby stabilizing the intermediate/transition state and enabling the desired reactivity. This is the first time that such second-sphere interaction and its impact on cross-coupling reactivity has been elucidated. The new insights gained from this study can help better understand and improve Heck-type reactions.
We present a detailed DFT mechanistic study on the first Ni-catalyzed direct carbonyl-Heck coupling of aryl triflates and aldehydes to afford ketones.
As the cost-effective and nontoxic alternative for hydrogen evolution reaction (HER), Co9S8 has attracted much attention. This paper explores the regulation of Zn doping impacted the unique ...nanostructure and electrocatalytic performance on Co9S8. Herein, utilizing copper foam (CF) as substrate, a series of different nanostructure of (Zn-)Co9S8@CF has been synthesized by accurately varying the ratio of Zn2+ to Co2+. Compared with aggregated pure Co9S8 and other different ratios contrast samples, Zn–Co9S8@CF-(1-1) with a zinc to cobalt ratio of 1 possesses highly dispersity which can be attributed to the novel nano-neuron network structure. The electrochemical measurements for HER demonstrate that Zn–Co9S8@CF-(1-1) not only reveals superior activity with small overpotentials to achieve a current density of 10 mA cm−2 in acidic (278 mV) and alkaline (273 mV) media, but also exhibits long-time durability in the solution with a wide range of pH. The excellent performance of Zn–Co9S8@CF-(1-1) can be attributed to the unique reticular structure which can facilitate exposure of numerous active sites and favorable long-term stability. The substrate of three-dimensional CF can provide the remarkable conductivity. This work provides a precise and effective approach to regulate three-dimensional nanostructure of Zn-doped electrocatalysts for HER.
Display omitted
•Zn–Co9S8 on copper foam (CF) with a nano-neuron network structure is synthesized.•The ratios of Zn2+ to Co2+ can affect the structure of Zn–Co9S8@CF.•Zn–Co9S8@CF exhibits excellent activity and long-time durability with a wide range of pH.•Zn doping is a promising method for construct the novel structure of electrocatalysts.
The design of electrocatalysts including precious and nonprecious metals for the hydrogen evolution reaction (HER) in alkaline media remains challenging due to the sluggish reaction kinetics caused ...by the additional water dissociation step. Herein, we fabricate tungsten-doped Ni-Co phosphides based on Ni foam (W-NiCoP/NF), which have multiple catalytic sites for water dissociation and H
2
formation steps, respectively. Physical and electrochemical studies imply that bimetallic Ni-Co sites are responsible for water dissociation by absorbing hydroxide, while the W atoms function as binding sites for hydrogen intermediates (H
ad
) in the second step of the alkaline HER process. Benefiting from the moderate combination ability between W and H atoms, W sites could effectively convert H
ad
to H
2
, and the synergistic effect between Ni-Co sites and W sites can accelerate the HER rate. W-NiCoP/NF exhibits a low overpotential of 29.6 mV at a current density of 10 mA cm
−2
and a small Tafel slope of 38 mV dec
−1
, which is close to that of the Pt/C catalyst. W-NiCoP/NF also displays excellent oxygen evolution reaction (OER) performance and thus outstanding performance for overall water splitting. This work may provide a way to modulate multisite catalysts based on transition metal phosphides for wider application in other electrolysis fields.
The design of electrocatalysts including precious and nonprecious metals for the hydrogen evolution reaction (HER) in alkaline media remains challenging due to the sluggish reaction kinetics caused by the additional water dissociation step.
PDF
