Microwave-Assisted Synthesis of Silver Vanadium Phosphorus Oxide, Ag₂VO₂PO₄: Crystallite Size Control and Impact on Electrochemistry

Silver vanadium phosphorus oxide, Ag₂VO₂PO₄, is a promising cathode material for Li batteries due in part to its large capacity and high current capability. Herein, a new synthesis of Ag₂VO₂PO₄ based on microwave heating is presented, where the reaction time is reduced by approximately 100× relative to other reported methods, and the crystallite size is controlled via synthesis temperature, showing a linear correlation of crystallite size with temperature. Notably, under galvanostatic reduction, the Ag₂VO₂PO₄ sample with the smallest crystallite size delivers the highest capacity and shows the highest loaded voltage. Further, pulse discharge tests show a significant resistance decrease during the initial discharge coincident with the formation of Ag metal. Thus, the magnitude of the resistance decrease observed during pulse tests depends on the Ag₂VO₂PO₄ crystallite size, with the largest resistance decrease observed for the smallest crystallite size. Additional electrochemical measurements indicate a quasi-reversible redox reaction involving Li⁺ insertion/deinsertion, with capacity fade due to structural changes associated with the discharge/charge process. In summary, this work demonstrates a faster synthetic approach for bimetallic polyanionic materials which also provides the opportunity for tuning of electrochemical properties through control of material physical properties such as crystallite size

Experimental discharge voltage profiles of disordered rocksalt cathodes

An open-source dataset of disordered rocksalt cathode electrochemical discharge voltages.</p

Transition Metal-Mediated CO and CC Bond-Forming Reactions: A Regioselective Strategy for the Synthesis of Imidazo[1,2‑<i>a</i>]pyridines and Imidazo[1,2‑<i>a</i>]pyrazines

A novel and convenient transformation for the regiospecific synthesis of functionalized imidazo­[1,2-<i>a</i>]­pyridine aldehydes/ketones and 3-vinyl imidazo­[1,2-<i>a</i>]­pyridines has been developed via copper­(I)- and palladium­(II)-catalyzed cyclization. The one-pot reaction proceeds smoothly with commercially available catalysts and affords the products in moderate to good yields. It represents an efficient approach for the formation of C–N, CO, and CC bonds under mild conditions

Genetic control of the root system in rice under normal and drought stress conditions by genome-wide association study

<div><p>A variety of adverse conditions including drought stress severely affect rice production. Root system plays a critical role in drought avoidance, which is one of the major mechanisms of drought resistance. In this study, we adopted genome-wide association study (GWAS) to dissect the genetic basis controlling various root traits by using a natural population consisting of 529 representative rice accessions. A total of 413 suggestive associations, containing 143 significant associations, were identified for 21 root traits, such as maximum root length, root volume, and root dry weight under normal and drought stress conditions at the maturation stage. More than 80 percent of the suggestive loci were located in the region of reported QTLs for root traits, while about 20 percent of suggestive loci were novel loci detected in this study. Besides, 11 reported root-related genes, including <i>DRO1</i>, <i>WOX11</i>, and <i>OsPID</i>, were found to co-locate with the association loci. We further proved that the association results can facilitate the efficient identification of causal genes for root traits by the two case studies of <i>Nal1</i> and <i>OsJAZ1</i>. These loci and their candidate causal genes provide an important basis for the genetic improvement of root traits and drought resistance.</p></div

Association of family history and physical activities with prevalence of MS according to IDF criteria among 13,505 women in rural China, the NMSS during 2007–2008.

a<p>Adjusted for age at interview and BMI.</p>b<p>Adjusted for age at interview, BMI, education level, income status, occupation, ever smoker, ever drinker and tea consumption in family history calculation, additionally adjusted for history of diabetes and CVD in physical activity calculation.</p>c<p>LPA: Leisure-time physical activity.</p>d<p>OPA: Occupational physical activity.</p>e<p>CPA: Commuting physical activity.</p>f<p>Score was sum of LPA, OPA, CPA by bicycle, walking and both walking and taking bus.</p>g<p>P for trend was calculated by entering the ordinal exposure as continuous parameters in the model.</p

Association of alcohol consumption and MS risk.

<p>Legend: Association of metabolic syndrome risk and alcohol intake by all beverage and rice wine among 13,505 women in rural China, the NMSS during 2007–2008.</p

Criteria of metabolic syndrome used in current study.

<p>Criteria of metabolic syndrome used in current study.</p

Phenotype comparison between normal and drought stress conditions.

<p>Phenotype comparison between normal and drought stress conditions.</p

Unveiling the Structural Evolution of Ag_1.2Mn₈O₁₆ under Coulombically Controlled (De)Lithiation

MnO₂ materials are considered promising cathode materials for rechargeable lithium, sodium, and magnesium batteries due to their earth abundance and environmental friendliness. One polymorph of MnO₂, α-MnO₂, has 2 × 2 tunnels (4.6 Å × 4.6 Å) in its structural framework, which provide facile diffusion pathways for guest ions. In this work, a silver-ion-containing α-MnO₂ (Ag_1.2Mn₈O₁₆) is examined as a candidate cathode material for Li based batteries. Electrochemical stability of Ag_1.2Mn₈O₁₆ is investigated through Coulombically controlled reduction under 2 or 4 molar electron equivalents (e.e.). Terminal discharge voltage remains almost constant under 2 e.e. of cycling, whereas it continuously decreases under repetitive reduction by 4 e.e. Thus, detailed structural analyses were utilized to investigate the structural evolution upon lithiation. Significant increases in lattice <i>a</i> (17.7%) and atomic distances (∼4.8%) are observed when <i>x</i> in Li_<i>x</i>Ag_1.2Mn₈O₁₆ is >4. Ag metal forms at this level of lithiation concomitant with a large structural distortion to the Mn–O framework. In contrast, lattice <i>a</i> only expands by 2.2% and Mn–O/Mn-Mn distances show minor changes (∼1.4%) at <i>x</i> < 2. The structural deformation (tunnel breakage) at <i>x</i> > 4 inhibits the recovery of the original structure, leading to poor cycle stability at high lithiation levels. This report establishes the correlation among local structure changes, amorphization processes, formation of Ag⁰, and long-term cycle stability for this silver-containing α-MnO₂ type material at both low and high lithiation levels

Genome-wide association results for 8 root traits.

<p>Manhattan plots (left) and quantile-quantile plots (right) are presented for (A) RWDD, (B) RWDN, (C) RVDN, (D) RVTN, (E) DRVD, (F) RWSN, (G) RVDD, and (H) RWTN. For the Manhattan plots, -log₁₀ <i>P</i>-values from a genome-wide scan were plotted against the position of the SNPs on each of 12 chromosomes and the horizontal grey dashed line indicates the suggestive threshold (<i>P</i> = 1.21×10⁻⁶). For the quantile-quantile plots, the horizontal axis indicates the -log₁₀-transformed expected <i>P</i>-values, and the vertical axis indicates the -log₁₀-transformed observed <i>P</i>-values. The names of reported root-related genes near the association signals are indicated.</p