5,5′-Di-4-pyridyl-2,2′-(p-phenyl­ene)di-1,3,4-oxadiazole

In the crystal structure of the title compound, C20H12N6O2, the mol­ecules are located on centres of inversion. The complete mol­ecule is almost planar, with a maximum deviation from the mean plane of 0.0657 (1) Å for the O atom. In the crystal, mol­ecules are stacked into columns elongated in the a axis direction. The centroid–centroid distances between the aromatic rings of the mol­ecules within the columns are 3.6406 (1) and 3.6287 (2) Å. Mol­ecules are additionally connected via weak inter­molecular C—H⋯N hydrogen bonding

(μ-5-Carb­oxy-1H-imidazole-4-carboxyl­ato-κ4 N 1,O 5:N 3,O 4)bis­[amminesilver(I)]

In the title compound, [Ag2(C5H2N2O4)(NH3)2], each of the two AgI atoms is coordinated by two N atoms from an ammonia mol­ecule and a 5-carb­oxy-1H-imidazole-4-carboxyl­ate ligand in an almost linear geometry, and by one carboxyl­ate O atom with a weak inter­action. The Ag atoms are assembled into a linear tetra­mer through Ag⋯Ag inter­actions. Each Ag tetra­mer is linked by four 5-carb­oxy-1H-imidazole-4-carboxyl­ate ligands, forming a puckered chain. The complex involves a strong intra­molecular O—H⋯O hydrogen bond

4-Hydr­oxy-6-[(4-hydr­oxy-1-oxo-1,2-dihydro­phthalazin-6-yl)carbon­yl]phthalazin-1(2H)-one

In the crystal structure of the title compound, C17H10N4O5, the mol­ecules lie on twofold axes (through the ketone bridge C and O atoms). The dihedral angle between the two phthalazine rings is 52.25 (1)°. In the crystal, inter­molecular N—H⋯O and O—H⋯O inter­actions link the mol­ecules

New definition of potential spicity by the least square method

Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 123 (2018): 7351-7365, doi:10.1029/2018JC014306.A differentiable function whose contours are orthogonal to potential density (σ) contours does not exist. However, such a function, called potential spicity (π), can be defined in the least square sense; these two functions form a practically orthogonal coordinate system in potential temperature‐salinity (θ‐S) space. Thus, in addition to the classical potential temperature‐salinity (θ‐S) diagram, seawater properties can be studied in the potential density‐potential spicity (σ − π) diagram.Guangzhou Science and Technology Program key projects. Grant Number: 201804020056 National Natural Science Foundation of China. Grant Numbers: 41476167, 91752108 National Natural Science Foundation of Guangdong Province, China Grant Number: 2016A030311042; Strategic Priority Research Program of the Chinese Academy of Sciences Grant Number: XDA11030302; Guangzhou Science and Technology Program; NSF of Guangdong Province, China2019-04-1

Comparative genomic analyses of Mycoplasma hyopneumoniae pathogenic 168 strain and its high-passaged attenuated strain

Background: Mycoplasma hyopneumoniae is the causative agent of porcine enzootic pneumonia (EP), a mild, chronic pneumonia of swine. Despite presenting with low direct mortality, EP is responsible for major economic losses in the pig industry. To identify the virulence-associated determinants of M. hyopneumoniae, we determined the whole genome sequence of M. hyopneumoniae strain 168 and its attenuated high-passage strain 168-L and carried out comparative genomic analyses. Results: We performed the first comprehensive analysis of M. hyopneumoniae strain 168 and its attenuated strain and made a preliminary survey of coding sequences (CDSs) that may be related to virulence. The 168-L genome has a highly similar gene content and order to that of 168, but is 4,483 bp smaller because there are 60 insertions and 43 deletions in 168-L. Besides these indels, 227 single nucleotide variations (SNVs) were identified. We further investigated the variants that affected CDSs, and compared them to reported virulence determinants. Notably, almost all of the reported virulence determinants are included in these variants affected CDSs. In addition to variations previously described in mycoplasma adhesins (P97, P102, P146, P159, P216, and LppT), cell envelope proteins (P95), cell surface antigens (P36), secreted proteins and chaperone protein (DnaK), mutations in genes related to metabolism and growth may also contribute to the attenuated virulence in 168-L. Furthermore, many mutations were located in the previously described repeat motif, which may be of primary importance for virulence. Conclusions: We studied the virulence attenuation mechanism of M. hyopneumoniae by comparative genomic analysis of virulent strain 168 and its attenuated high-passage strain 168-L. Our findings provide a preliminary survey of CDSs that may be related to virulence. While these include reported virulence-related genes, other novel virulence determinants were also detected. This new information will form the foundation of future investigations into the pathogenesis of M. hyopneumoniae and facilitate the design of new vaccines

Phylogeny and evolutionary history of Leymus (Triticeae; Poaceae) based on a single-copy nuclear gene encoding plastid acetyl-CoA carboxylase

<p>Abstract</p> <p>Background</p> <p>Single- and low- copy genes are less likely subject to concerted evolution, thus making themselves ideal tools for studying the origin and evolution of polyploid taxa. <it>Leymus </it>is a polyploid genus with a diverse array of morphology, ecology and distribution in Triticeae. The genomic constitution of <it>Leymus </it>was assigned as NsXm, where Ns was presumed to be originated from <it>Psathyrostachys</it>, while Xm represented a genome of unknown origin. In addition, little is known about the evolutionary history of <it>Leymus</it>. Here, we investigate the phylogenetic relationship, genome donor, and evolutionary history of <it>Leymus </it>based on a single-copy nuclear <it>Acc1 </it>gene.</p> <p>Results</p> <p>Two homoeologues of the <it>Acc1 </it>gene were isolated from nearly all the sampled <it>Leymus </it>species using allele-specific primer and were analyzed with those from 35 diploid taxa representing 18 basic genomes in Triticeae. Sequence diversity patterns and genealogical analysis suggested that (1) <it>Leymus </it>is closely related to <it>Psathyrostachys</it>, <it>Agropyron</it>, and <it>Eremopyrum</it>; (2) <it>Psathyrostachys juncea </it>is an ancestral Ns-genome donor of <it>Leymus </it>species; (3) the Xm genome in <it>Leymus </it>may be originated from an ancestral lineage of <it>Agropyron </it>and <it>Eremopyrum triticeum</it>; (4) the <it>Acc1 </it>sequences of <it>Leymus </it>species from the Qinghai-Tibetan plateau are evolutionarily distinct; (5) North America <it>Leymus </it>species might originate from colonization via the Bering land bridge; (6) <it>Leymus </it>originated about 11-12MYA in Eurasia, and adaptive radiation might have occurred in <it>Leymus </it>during the period of 3.7-4.3 MYA and 1.7-2.1 MYA.</p> <p>Conclusion</p> <p><it>Leymus </it>species have allopolyploid origin. It is hypothesized that the adaptive radiation of <it>Leymus </it>species might have been triggered by the recent upliftings of the Qinghai-Tibetan plateau and subsequent climatic oscillations. Adaptive radiation may have promoted the rapid speciation, as well as the fixation of unique morphological characters in <it>Leymus</it>. Our results shed new light on our understanding of the origin of Xm genome, the polyploidization events and evolutionary history of <it>Leymus </it>that could account for the rich diversity and ecological adaptation of <it>Leymus </it>species.</p

Epidemiology, causes, clinical manifestation and diagnosis, prevention and control of coronavirus disease (COVID-19) during the early outbreak period

__Background:__ The coronavirus disease (COVID-19) has been identified as the cause of an outbreak of respiratory illness in Wuhan, Hubei Province, China beginning in December 2019. As of 31 January 2020, this epidemic had spread to 19 countries with 11 791 confirmed cases, including 213 deaths. The World Health Organization has declared it a Public Health Emergency of International Concern. __Methods:__ A scoping review was conducted following the methodological framework suggested by Arksey and O'Malley. In this scoping review, 65 research articles published before 31 January 2020 were analyzed and discussed to better understand the epidemiology, causes, clinical diagnosis, prevention and control of this virus. The research domains, dates of publication, journal language, authors' affiliations, and methodological characteristics were included in the analysis. All the findings and statements in this review regarding the outbreak are based on published information as listed in the references. __Results:__ Most of the publications were written using the English language (89.2%). The largest proportion of published articles were related to causes (38.5%) and a majority (67.7%) were published by Chinese scholars. Research articles initially focused on causes, but over time there was an increase of the articles related to prevention and control. Studies thus far have shown that the virus' origination is in connection to a seafood market in Wuhan, but specific animal associations have not been confirmed. Reported symptoms include fever, cough, fatigue, pneumonia, headache, diarrhea, hemoptysis, and dyspnea. Preventive measures such as masks, hand hygiene practices, avoidance of public contact, case detection, contact tracing, and quarantines have been discussed as

Near-real-time monitoring of global CO₂ emissions reveals the effects of the COVID-19 pandemic

The COVID-19 pandemic is impacting human activities, and in turn energy use and carbon dioxide (CO₂) emissions. Here we present daily estimates of country-level CO2 emissions for different sectors based on near-real-time activity data. The key result is an abrupt 8.8% decrease in global CO₂ emissions (−1551 Mt CO₂) in the first half of 2020 compared to the same period in 2019. The magnitude of this decrease is larger than during previous economic downturns or World War II. The timing of emissions decreases corresponds to lockdown measures in each country. By July 1st, the pandemic’s effects on global emissions diminished as lockdown restrictions relaxed and some economic activities restarted, especially in China and several European countries, but substantial differences persist between countries, with continuing emission declines in the U.S. where coronavirus cases are still increasing substantially