Determination of Inorganic Anions and Melamine in Fertilizers by Ion Chromatography

A chromatographic analysis method for determining inorganic anions and melamine in fertilizers was established using ion chromatography(IC).The fertilizer samples were extracted by ultrasonic method with 7 g/L trichloroacetic acid solution and centrifuged.The supernatant is purified by a solid phase extraction column.Then,the anions in the solution were purified using SH-AP-1(250 mm×4.0 mm)as a separation column,and measured by a suppressed conductivity detector;the melamine in the solution was separated using SH-CC-4(200 mm×4.0 mm)as a separation column and detected by a UV detector.The results show that the mass concentration of anions had a linear relationship with its peak area within a certain range,the linear correlation coefficient r of the standard curve was greater than 0.999,the recovery rate of spiked samples was 93.4%-104.4%,and the relative standard deviation(RSD)of the measured value(n=6)was less than 4%.Thus,this method is widely suitable for detection of anions and cations in a variety of fertilizer samples.

Solution-Processed Hybrid Europium (Ⅱ) lodide Scintillator for Sensitive X-Ray Detection

Lead halide perovskite nanocrystals have recently demonstrated great potential as x-ray scintillators,yet they stll suffer toxicity issues,inferior light yield(LY)caused by severe self-absorption.Nontoxic bivalent europium ions(Eu^(2+))with intrinsically efficient and self-absorption-free d-f transition are a prospective replacement for the toxic Pb^(2+).Here,we demonstrated solution-processed organic-inorganic hybrid halide BA_(10)Eul_(12)(BA denotes C_(4)H_(9)NH_(4)^(+))single crystals for the first time.

Perovskite nanocrystals:synthesis,properties and applications

Halide perovskites have emerged as superstar materials for optoelectronic devices. Besides the fever of research in solar cells, these materials show great promise on light emitting diodes(LEDs), photodetectors and lasers as well. Rapid advances in bulk perovskite materials aroused universal interest for the development of perovskite nanocrystals, inspired by the great progress of classic colloidal semiconductor quantum dots. Perovskite nanocrystals have been synthesized based on solution process and exhibited high luminescence quantum yield, sharp emission peak, and emission color tunability. Significant progresses have been made about the application of perovskite nanocrystals for LED and lasers in recent years. In this paper, we will comprehensively introduce the synthesis strategies, physical and chemical characteristics, as well as their applications in optoelectronic devices.

Supersaturation controlled growth of MAFAPbI3 perovskite film for high efficiency solar cells

Controlling the nucleation and growth of organic-inorganic hybrids perovskite is of key importance to improve the morphology and crystallinity of perovskite films. However, the growth mechanism of perovskite films based on classical crystallization theory is not fully understood. Here, we develop a supersaturation controlled strategy(SCS) to balance the nucleation and crystal growth speeds. By this strategy, we are able to find an ideal supersaturation region to realize a balance of nucleation and crystal growth, which yields highly crystallized perovskite films with micrometer-scale grains. Besides, we provide a thoughtful analysis of nucleation and growth based on the fabrication of the perovskite films. As a result, the highest photovoltaic power conversion efficiencies(PCE) of 19.70% and 20.31% are obtained for the planar and the meso-superstructured devices, respectively. This strategy sheds some light for understanding the film growth mechanism of high quality perovskite film, and it provides a facile strategy to fabricate high efficiency perovskite solar cells.

Material exploration via designing spatial arrangement of octahedral units: a case study of lead halide perovskites

Halide perovskites have attracted tremendous attention as semiconducting materials for various optoelectronic applications.The functional metal-halide octahedral units and their spatial arrangements play a key role in the optoelectronic properties of these materials.At present,most of the efforts for material exploration focus on substituting the constituent elements of functional octahedral units,whereas designing the spatial arrangement of the functional units has received relatively little consideration.In this work,via a global structure search based on density functional theory(DFT),we discovered a metastable three-dimensional honeycomb-like perovskite structure with the functional octahedral units arranged through mixed edge-and comer-sharing.We experimentally confirmed that the honeycomb-like perovskite structure can be stabilized by divalent molecular cations with suitable size and shape,such as 2,2’-bisimidazole(BIM).DFT calculations and experimental characterizations revealed that the honeycomb-like perovskite with the formula of BIMPb2l6,synthesized through a solution process,exhibits high electronic dimensionality,a direct allowed bandgap of 2.1 eV,small effective masses for both electrons and holes,and high optical absorption coefficients,which indicates a significant potential for optoelectronic applications.The employed combination of DFT and experimental study provides an exemplary approach to explore prospective optoelectronic semiconductors via spatially arranging functional units.

Increased EZH2 Levels in Anterior Cingulate Cortex Microglia Aggravate Neuropathic Pain by Inhibiting Autophagy Following Brachial Plexus Avulsion in Rats

After brachial plexus avulsion(BPA),microglia induce inflammation,initiating and maintaining neuropathic pain.EZH2(enhancer of zeste homolog 2) has been implicated in inflammation and neuropathic pain,but the mechanisms by which it regulates neuropathic pain remain unclear.Here,we found that EZH2 levels were markedly upregulated during BPA-induced neuropathic pain in vivo and in vitro,stimulating pro-inflammatory cytokines(IL-1β,TNF-α,and IL-6) secretion in vivo.In rats with BPAinduced neuropathic pain,mechanical and cold hypersensitivities were induced by EZH2 upregulation and inhibited by EZH2 downregulation in the anterior cingulate cortex.Microglial autophagy was also significantly inhibited,with EZH2 inhibition activating autophagy and reducing neuroinflammation in vivo.However,this effect was impaired by inhibiting autophagy with 3-methyladenine,suggesting that the MTOR signaling pathway is a functional target of EZH2.These data suggest that EZH2 regulates neuroinflammation and neuropathic pain via a novel MTOR-mediated autophagy signaling pathway,providing a promising approach for managing neuropathic pain.

NPC1-regulated dynamic of clathrin-coated pits is essential for viral entry

Viruses utilize cellular lipids and manipulate host lipid metabolism to ensure their replication and spread.Therefore,the identification of lipids and metabolic pathways that are suitable targets for antiviral development is crucial.Using a library of compounds targeting host lipid metabolic factors and testing them for their ability to block pseudorabies virus(PRV)and vesicular stomatitis virus(VSV)infection,we found that U18666A,a specific inhibitor of Niemann-Pick C1(NPC1),is highly potent in suppressing the entry of diverse viruses including pseudotyped severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).NPC1 deficiency markedly attenuates viral growth by decreasing cholesterol abundance in the plasma mem-brane,thereby inhibiting the dynamics of clathrin-coated pits(CCPs),which are indispensable for clathrin-mediated endocytosis.Significantly,exogenous cholesterol can complement the dynamics of CCPs,leading to efficient viral entry and infectivity.Administration of U18666A improves the survival and pathology of PRV-and influenza A virus-infected mice.Thus,our studies demonstrate a unique mechanism by which NPC1 inhibition achieves broad antiviral activity,indicating a potential new therapeutic strategy against SARS-CoV-2,as well as other emerging viruses.

An integrative analysis of miRNA and mRNA expression in the brains of Alzheimer's disease transgenic mice after real-world PM_(2.5)exposure

Fine particulate matter(PM_(2.5))is associated with increased risks of Alzheimer's disease(AD),yet the toxicological mechanisms of PM_(2.5)promoting AD remain unclear.In this study,wildtype and APP/PS1 transgenic mice(AD mice)were exposed to either filtered air(FA)or PM_(2.5)for eight weeks with a real-world exposure system in Taiyuan,China(mean PM_(2.5)concentration in the cage was 61μg/m~3).We found that PM_(2.5)exposure could remarkably aggravate AD mice's ethological and brain ultrastructural damage,along with the elevation of the pro-inflammatory cytokines(IL-6 and TNF-α),Aβ-42 and ACh E levels and the decline of Ch AT levels in the brains.Based on high-throughput sequencing results,some differentially expressed(DE)m RNAs and DE mi RNAs in the brains of AD mice after PM_(2.5)exposure were screened.Using RT-q PCR,seven DE mi RNAs(mmu-mi R-193b-5p,122b-5p,466h-3p,10b-5p,1895,384–5p,and 6412)and six genes(Pcdhgb8,Unc13b,Robo3,Prph,Pter,and Tbata)were evidenced the and verified.Two mi RNA-target gene pairs(mi R-125b-Pcdhgb8 pair and mi R-466h-3p-IL-17Rα/TGF-βR2/Aβ-42/ACh E pairs)were demonstrated that they were more related to PM_(2.5)-induced brain injury.Results of Gene Ontology(GO)pathways and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathways predicted that synaptic and postsynaptic regulation,axon guidance,Wnt,MAPK,and m TOR pathways might be the possible regulatory mechanisms associated with pathological response.These revealed that PM_(2.5)-elevated pro-inflammatory cytokine levels and PM_(2.5)-altered neurotransmitter levels in AD mice could be the important causes of brain damage and proposed the promising mi RNA and m RNA biomarkers and potential mi RNA-m RNA interaction networks of PM_(2.5)-promoted AD.

Synthesis of Clionastatins A and B through Enhancement of Chlorination and Oxidation Levels of Testosterone

A full account of semisyntheses of polychlorinated marine steroids clionastatins A and B is described.We have developed a unique two-stage chlorination-oxidation strategy that enabled concise and divergent semisyntheses of clionastatins A and B in 16 steps from inexpensive testosterone.Key transformations in chlorination stage include(a)conformationally controlled,stereospecific dichlorination through an unusualβ-chloronium intermediate to install the diequatorial C1,C2-dichloride;(b)C4-OH directed C19–H oxygenation followed by challenging neopentyl chlorination to install the C19–Cl.The high oxidation level was constructed through(a)the desaturation at C6–C7 through one-pot photochemical dibromination–reductive debromination;(b)regioselective anti-Markovnikov oxidation of the C6–C7 double bond by photoredox-metal dual catalysis to forge the B ring enone;(c)late-stage desaturation with SeO_(2)to introduce C8–C9 double bond.Wharton transposition was used to forge the D-ring enone,and thermodynamically driven epimerization secured the cis-fused C/D ring system.Furthermore,we also provided a 14-step approach to clionastatin A by optimizing the construction of the D-ring enone with a dehydration-oxidation sequence.