Members of the genus Streptococcus within the phylum Firmicutes are among the most diverse and significant zoonotic pathogens. This genus has gone through considerable taxonomic revision due to ...increasing improvements of chemotaxonomic approaches, DNA hybridization and 16S rRNA gene sequencing. It is proposed to place the majority of streptococci into "species groups". However, the evolutionary implications of species groups are not clear presently. We use comparative genomic approaches to yield a better understanding of the evolution of Streptococcus through genome dynamics, population structure, phylogenies and virulence factor distribution of species groups. Genome dynamics analyses indicate that the pan-genome size increases with the addition of newly sequenced strains, while the core genome size decreases with sequential addition at the genus level and species group level. Population structure analysis reveals two distinct lineages, one including Pyogenic, Bovis, Mutans and Salivarius groups, and the other including Mitis, Anginosus and Unknown groups. Phylogenetic dendrograms show that species within the same species group cluster together, and infer two main clades in accordance with population structure analysis. Distribution of streptococcal virulence factors has no obvious patterns among the species groups; however, the evolution of some common virulence factors is congruous with the evolution of species groups, according to phylogenetic inference. We suggest that the proposed streptococcal species groups are reasonable from the viewpoints of comparative genomics; evolution of the genus is congruent with the individual evolutionary trajectories of different species groups.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Iron fluoride, an intercalation-conversion cathode for lithium ion batteries, promises a high theoretical energy density of 1922 Wh kg
However, poor electrochemical reversibility due to repeated ...breaking/reformation of metal fluoride bonds poses a grand challenge for its practical application. Here we report that both a high reversibility over 1000 cycles and a high capacity of 420 mAh g
can be realized by concerted doping of cobalt and oxygen into iron fluoride. In the doped nanorods, an energy density of ~1000 Wh kg
with a decay rate of 0.03% per cycle is achieved. The anion's and cation's co-substitutions thermodynamically reduce conversion reaction potential and shift the reaction from less-reversible intercalation-conversion reaction in iron fluoride to a highly reversible intercalation-extrusion reaction in doped material. The co-substitution strategy to tune the thermodynamic features of the reactions could be extended to other high energy conversion materials for improved performance.
Hydroxide exchange membrane fuel cells offer possibility of adopting platinum-group-metal-free catalysts to negotiate sluggish oxygen reduction reaction. Unfortunately, the ultrafast hydrogen ...oxidation reaction (HOR) on platinum decreases at least two orders of magnitude by switching the electrolytes from acid to base, causing high platinum-group-metal loadings. Here we show that a nickel-molybdenum nanoalloy with tetragonal MoNi
phase can catalyze the HOR efficiently in alkaline electrolytes. The catalyst exhibits a high apparent exchange current density of 3.41 milliamperes per square centimeter and operates very stable, which is 1.4 times higher than that of state-of-the-art Pt/C catalyst. With this catalyst, we further demonstrate the capability to tolerate carbon monoxide poisoning. Marked HOR activity was also observed on similarly designed WNi
catalyst. We attribute this remarkable HOR reactivity to an alloy effect that enables optimum adsorption of hydrogen on nickel and hydroxyl on molybdenum (tungsten), which synergistically promotes the Volmer reaction.
The effect of H2O in electrolytes and in electrode lattices on the thermodynamics and kinetics of reversible multivalent‐ion intercalation chemistry based on a model platform of layered VOPO4 has ...been investigated. The presence of H2O at the electrolyte/electrode interface plays a key role in assisting Zn2+ diffusion from electrolyte to the surface, while H2O in the lattice structure alters the working potential. More importantly, a dynamic equilibrium between bulk electrode and electrolyte is eventually reached for H2O transport during the charge/discharge cycles, with the water activity serving as the key parameter determining the direction of water movement and the cycling stability.
Water of life: H2O at the electrolyte/electrode interface plays a key role in assisting Zn2+ diffusion from electrolytes to the bulk surface, while H2O in the lattice structure alters the working potential. A dynamic equilibrium between the bulk electrode and electrolyte is eventually established for H2O transport during the charge/discharge cycles.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Alkaline fuel cells can permit the adoption of platinum group metal‐free (PGM‐free) catalysts and cheap bipolar plates, thus further lowering the cost. With the exploration of PGM‐free hydrogen ...oxidation reaction (HOR) catalysts, nickel‐based compounds have been considered as the most promising HOR catalysts in alkali. Here we report an interfacial engineering through the formation of nickel‐vanadium oxide (Ni/V2O3) heterostructures to activate Ni for efficient HOR catalysis in alkali. The strong electron transfer from Ni to V2O3 could modulate the electronic structure of Ni sites. The optimal Ni/V2O3 catalyst exhibits a high intrinsic activity of 0.038 mA cm−2 and outstanding stability. Experimental and theoretical studies reveal that Ni/V2O3 interface as the active sites can enable to optimize the hydrogen and hydroxyl bindings, as well as protect metallic Ni from extensive oxidation, thus achieving the notable activity and durability.
An interfacial engineering approach was developed to fabricate a low‐cost Ni/V2O3 heterostructure catalyst, which can efficiently and stably catalyze the hydrogen oxidation reaction (HOR) in alkaline media. Experimental and theoretical studies reveal that the Ni/V2O3 interface sites can optimize the hydrogen and hydroxyl bindings, as well as protect metallic Ni from extensive oxidation, thus achieving the notable HOR performance.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Li-Ion batteries (LIBs) are approaching their energy limits imposed by their intercalation chemistry nature. As alternatives, multivalent (MV) chemistries bring both promises and challenges, with the ...main obstacle being the sluggish diffusion of MV-cations due to their strong electrostatic interaction with host lattices. In this work, we demonstrated that polyanion based robust crystal architecture could enable ultrafast and reversible Zn2+-intercalation and de-intercalation at a high working voltage. The nominal bivalence of Zn2+ was successfully delocalized by multiple atoms through the p–d hybridization between the V-d and O-p orbitals; hence the inserted Zn2+ only bears an effective charge of 1.336, rendering its high mobility. The novel aqueous rechargeable 1.7 V Zn/LiV2(PO4)3 cell based on such a mechanism delivers a high power density (8000 W kg−1 at 60C) comparable to supercapacitors, and a high energy density (218 W h kg−1 at 1C) close to LIBs, with an extraordinarily long cycle life of 4000 cycles. All of these parameters far exceed those of Zn batteries reported so far. The cell-level volumetric and specific energy densities of the Zn/LiV2(PO4)3 cell are 320 W h L−1 and 150 W h kg−1, respectively, which are even better than those of first-generation LIBs. Combined with the intrinsic safety of its aqueous chemistry and its wide working temperature range, this cell makes a strong candidate for automotive applications.
BACKGROUND—There is a paucity of data from large cohort studies examining the prognostic significance of obstructive sleep apnea (OSA) in patients with coronary artery disease. We hypothesized that ...OSA predicts subsequent major adverse cardiac and cerebrovascular events (MACCEs) in patients undergoing percutaneous coronary intervention.
METHODS AND RESULTS—The Sleep and Stent Study was a prospective, multicenter registry of patients successfully treated with percutaneous coronary intervention in 5 countries. Between December 2011 and April 2014, 1748 eligible patients were prospectively enrolled. The 1311 patients who completed a sleep study within 7 days of percutaneous coronary intervention formed the cohort for this analysis. Drug-eluting stents were used in 80.1% and bioresorbable vascular scaffolds in 6.3% of the patients, and OSA, defined as an apnea-hypopnea index of ≥15 events per hour, was found in 45.3%. MACCEs, a composite of cardiovascular mortality, nonfatal myocardial infarction, nonfatal stroke, and unplanned revascularization, occurred in 141 patients during the median follow-up of 1.9 years (interquartile range, 0.8 years). The crude incidence of an MACCEs was higher in the OSA than the non-OSA group (3-year estimate, 18.9% versus 14.0%; p=0.001). Multivariate Cox regression analysis indicated that OSA was a predictor of MACCEs, with an adjusted hazard ratio of 1.57 (95% confidence interval, 1.10–2.24; P=0.013), independently of age, sex, ethnicity, body mass index, diabetes mellitus, and hypertension.
CONCLUSIONS—OSA is independently associated with subsequent MACCEs in patients undergoing percutaneous coronary intervention. Evaluation of therapeutic approaches to mitigate OSA-associated risk is warranted.
CLINICAL TRIAL REGISTRATION—URLhttp://www.clinicaltrials.gov. Unique identifierNCT01306526.
Adding a 200-mile range in 10 min, so-called extreme fast charging (XFC), is the key to mainstream adoption of battery electric vehicles (BEVs). Here, we present an asymmetric temperature modulation ...(ATM) method that, on one hand, charges a Li-ion cell at an elevated temperature of 60°C to eliminate Li plating and, on the other, limits the exposure time at 60°C to only ∼10 min per cycle, or 0.1% of the lifetime of a BEV, to prevent severe solid-electrolyte-interphase growth. The asymmetric temperature between charge and discharge opens a new path to enhance kinetics and transport during charging while still achieving long life. We show that a 9.5-Ah 170-Wh/kg cell sustained 1,700 XFC cycles (6 C charge to 80% state of charge) at 20% capacity loss with the ATM, compared to 60 cycles for a control cell, and that a 209-Wh/kg BEV cell retained 91.7% capacity after 2,500 XFC cycles.
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•Asymmetric charge and discharge temperatures enable durable extreme fast charging•High-temperature charging eliminates Li plating by enhanced transport and kinetics•Limited exposure time to high temperature avoids severe SEI growth•Elevated charging temperature reduces battery cooling need by >12×
Electric vehicles will only be truly competitive when they can be charged as fast as refilling a gas tank. The US Department of Energy has set a goal of developing extreme fast charging (XFC) technology that can add 200 miles of driving range in 10 min. A critical barrier to XFC is Li plating, which usually occurs at high charge rates and drastically deteriorates battery life and safety. Here, we present an asymmetric temperature modulation (ATM) method that charges a Li-ion cell at an elevated temperature of 60°C to eliminate Li plating and limits the exposure time to 60°C to only ∼10 min per cycle to prevent serious materials degradation. Using industrially available battery materials, we show that a high-energy (209 Wh/kg) Li-ion cell with the ATM method retains 91.7% capacity after 2,500 XFC cycles (equal to 500,000 miles of driving range), far exceeding the US Department of Energy (DOE) target (500 cycles at 20% loss).
An asymmetric temperature modulation method is presented in which a Li-ion cell is rapidly pre-heated to and charged at ∼60°C, and the cell’s exposure time to 60°C is limited to ∼10 min per cycle. The elevated temperature enhances kinetics and transport and hence eliminates Li plating; the limited exposure time to 60°C avoids severe materials degradation. We demonstrate that a high energy (209 Wh/kg) cell retains 91.7% capacity after 2,500 cycles of 10-min extreme fast charging, far exceeding the DOE target.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this article, we propose a new factorization technique for nonlinear ODEs involving local fractional derivatives for the first time. By making use of the traveling-wave transformation, the exact ...solutions for nonlinear local fractional FitzHugh–Nagumo and Newell–Whitehead equations are given. The obtained results illustrate that the proposed method is efficient and accurate for finding the exact solutions for a class of local fractional PDEs occurring in mathematical physics.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A dynamical model of spinning multi-span pipes conveying fluid is proposed.•The functionally graded materials (FGMs) are applied in the structure to get various vibration characteristics.•The ...intermediate supports can heighten the rigidity and improve the stability of spinning drill strings.•The mode rules obtained would facilitate to estimate the locations of vibration amplitude of multi-span drill strings.
In this paper, a dynamical model of spinning multi-span pipes conveying fluid is proposed and the transverse natural and resonant frequencies and mode characteristics of such system are explored. The pipe body is considered to be composed of functionally graded materials (FGMs), in which a power law is used to govern the distribution of material properties along the pipe wall thickness. The partial differential equations (PDEs) governing two transverse motions of the pipe are derived by the extended Hamilton principle, in which the contributions of the FGM and intermediate supports are highlighted. The PDEs are discretized by the Galerkin procedure and the eigensystem theorem is applied to find the numerical solutions. The results show that various frequency characteristics can be attainable by use of different materials and mixing patterns. Attachments of intermediate supports can heighten the rigidity and improve the stability of spinning FG pipes conveying fluid, which are consequently used as “stabilizers” for the slender drill strings. Also, the mode characteristics of different spans will determine the locations of vibration amplitude of the pipes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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