Estimating the thickness of diffusive solid electrolyte interface

NASA Astrophysics Data System (ADS)

Wang, XiaoHe; Shen, WenHao; Huang, XianFu; Zang, JinLiang; Zhao, YaPu

2017-06-01

The solid electrolyte interface (SEI) is a hierarchical structure formed in the transition zone between the electrode and the electrolyte. The properties of lithium-ion (Li-ion) battery, such as cycle life, irreversible capacity loss, self-discharge rate, electrode corrosion and safety are usually ascribed to the quality of the SEI, which are highly dependent on the thickness. Thus, understanding the formation mechanism and the SEI thickness is of prime interest. First, we apply dimensional analysis to obtain an explicit relation between the thickness and the number density in this study. Then the SEI thickness in the initial charge-discharge cycle is analyzed and estimated for the first time using the Cahn-Hilliard phase-field model. In addition, the SEI thickness by molecular dynamics simulation validates the theoretical results. It has been shown that the established model and the simulation in this paper estimate the SEI thickness concisely within order-of-magnitude of nanometers. Our results may help in evaluating the performance of SEI and assist the future design of Li-ion battery.

High-Performance Cells Containing Lithium Metal Anodes, LiNi0.6Co0.2Mn0.2O2 (NCM 622) Cathodes, and Fluoroethylene Carbonate-Based Electrolyte Solution with Practical Loading.

PubMed

Salitra, Gregory; Markevich, Elena; Afri, Michal; Talyosef, Yosef; Hartmann, Pascal; Kulisch, Joern; Sun, Yang-Kook; Aurbach, Doron

2018-06-13

We report on the highly stable lithium metal|LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM 622) cells with practical electrodes' loading of 3.3 mA h g -1 , which can undergo many hundreds of stable cycles, demonstrating high rate capability. A key issue was the use of fluoroethylene carbonate (FEC)-based electrolyte solutions (1 M LiPF 6 in FEC/dimethyl carbonate). Li|NCM 622 cells can be cycled at 1.5 mA cm -2 for more than 600 cycles, whereas symmetric Li|Li cells demonstrate stable performance for more than 1000 cycles even at higher areal capacity and current density. We attribute the excellent performance of both Li|NCM and Li|Li cells to the formation of a stable and efficient solid electrolyte interphase (SEI) on the surface of the Li metal electrodes cycled in FEC-based electrolyte solutions. The composition of the SEI on the Li and the NCM electrodes is analyzed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. A drastic capacity fading of Li|NCM cells is observed, followed by spontaneous capacity recovery during prolonged cycling. This phenomenon depends on the current density and the amount of the electrolyte solution and relates to kinetic limitations because of SEI formation on the Li anodes in the FEC-based electrolyte solution.

Offset Initial Sodium Loss To Improve Coulombic Efficiency and Stability of Sodium Dual-Ion Batteries.

PubMed

Ma, Ruifang; Fan, Ling; Chen, Suhua; Wei, Zengxi; Yang, Yuhua; Yang, Hongguan; Qin, Yong; Lu, Bingan

2018-05-09

Sodium dual-ion batteries (NDIBs) are attracting extensive attention recently because of their low cost and abundant sodium resources. However, the low capacity of the carbonaceous anode would reduce the energy density, and the formation of the solid-electrolyte interphase (SEI) in the anode during the initial cycles will lead to large amount consumption of Na + in the electrolyte, which results in low Coulombic efficiency and inferior stability of the NDIBs. To address these issues, a phosphorus-doped soft carbon (P-SC) anode combined with a presodiation process is developed to enhance the performance of the NDIBs. The phosphorus atom doping could enhance the electric conductivity and further improve the sodium storage property. On the other hand, an SEI could preform in the anode during the presodiation process; thus the anode has no need to consume large amounts of Na + to form the SEI during the cycling of the NDIBs. Consequently, the NDIBs with P-SC anode after the presodiation process exhibit high Coulombic efficiency (over 90%) and long cycle stability (81 mA h g -1 at 1000 mA g -1 after 900 cycles with capacity retention of 81.8%), far more superior to the unsodiated NDIBs. This work may provide guidance for developing high performance NDIBs in the future.

Lithium Dinitramide as an Additive in Lithium Power Cells

NASA Technical Reports Server (NTRS)

Gorkovenko, Alexander A.

2007-01-01

Lithium dinitramide, LiN(NO2)2 has shown promise as an additive to nonaqueous electrolytes in rechargeable and non-rechargeable lithium-ion-based electrochemical power cells. Such non-aqueous electrolytes consist of lithium salts dissolved in mixtures of organic ethers, esters, carbonates, or acetals. The benefits of adding lithium dinitramide (which is also a lithium salt) include lower irreversible loss of capacity on the first charge/discharge cycle, higher cycle life, lower self-discharge, greater flexibility in selection of electrolyte solvents, and greater charge capacity. The need for a suitable electrolyte additive arises as follows: The metallic lithium in the anode of a lithium-ion-based power cell is so highly reactive that in addition to the desired main electrochemical reaction, it engages in side reactions that cause formation of resistive films and dendrites, which degrade performance as quantified in terms of charge capacity, cycle life, shelf life, first-cycle irreversible capacity loss, specific power, and specific energy. The incidence of side reactions can be reduced through the formation of a solid-electrolyte interface (SEI) a thin film that prevents direct contact between the lithium anode material and the electrolyte. Ideally, an SEI should chemically protect the anode and the electrolyte from each other while exhibiting high conductivity for lithium ions and little or no conductivity for electrons. A suitable additive can act as an SEI promoter. Heretofore, most SEI promotion was thought to derive from organic molecules in electrolyte solutions. In contrast, lithium dinitramide is inorganic. Dinitramide compounds are known as oxidizers in rocket-fuel chemistry and until now, were not known as SEI promoters in battery chemistry. Although the exact reason for the improvement afforded by the addition of lithium dinitramide is not clear, it has been hypothesized that lithium dinitramide competes with other electrolyte constituents to react with lithium on the surface of the anode to form a beneficial SEI. Apparently, nitrides and oxides that result from reduction of lithium dinitramide on the anode produce a thin, robust SEI different from the SEIs formed from organic SEI promoters. The SEI formed from lithium dinitramide is more electronically insulating than is the film formed in the presence of an otherwise identical electrolyte that does not include lithium dinitramide. SEI promotion with lithium dinitramide is useful in batteries with metallic lithium and lithium alloy anodes.

Determination of the Solid Electrolyte Interphase Structure Grown on a Silicon Electrode Using a Fluoroethylene Carbonate Additive

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veith, Gabriel M.; Doucet, Mathieu; Sacci, Robert L.

2017-07-24

In this work we explore how an electrolyte additive (fluorinated ethylene carbonate – FEC) mediates the thickness and composition of the solid electrolyte interphase formed over a silicon anode in situ as a function of state-of-charge and cycle. We show the FEC condenses on the surface at open circuit voltage then is reduced to C-O containing polymeric species around 0.9 V (vs. Li/Li +). The resulting film is about 50 Å thick. Upon lithiation the SEI thickens to 70 Å and becomes more organic-like. With delithiation the SEI thins by 13 Å and becomes more inorganic in nature, consistent withmore » the formation of LiF. This thickening/thinning is reversible with cycling and shows the SEI is a dynamic structure. We compare the SEI chemistry and thickness to 280 Å thick SEI layers produced without FEC and provide a mechanism for SEI formation using FEC additives.« less

Mechanistic elucidation of thermal runaway in potassium-ion batteries

NASA Astrophysics Data System (ADS)

Adams, Ryan A.; Varma, Arvind; Pol, Vilas G.

2018-01-01

For the first time, thermal runaway of charged graphite anodes for K-ion batteries is investigated, using differential scanning calorimetry (DSC) to probe the exothermic degradation reactions. Investigated parameters such as state of charge, cycle number, surface area, and binder demonstrate strong influences on the DSC profiles. Thermal runaway initiates at 100 °C owing to KxC8 - electrolyte reactions, but the K-ion graphite anode evolves significantly less heat as compared to the analogous Li-ion system (395 J g-1 vs. 1048 J g-1). The large volumetric expansion of graphite during potassiation cracks the SEI layer, enabling contact and reaction of KC8 - electrolyte, which diminishes with cycle number due to continuous SEI growth. High surface area graphite decreases the total heat generation, owing to thermal stability of the K-ion SEI layer. These findings illustrate the dynamic nature of K-ion thermal runaway and its many contrasts with the Li-ion graphite system, permitting possible engineering solutions for safer batteries.

Degradation Mechanisms of Electrochemically Cycled Graphite Anodes in Lithium-ion Cells

NASA Astrophysics Data System (ADS)

Bhattacharya, Sandeep

This research is aimed at developing advanced characterization methods for studying the surface and subsurface damage in Li-ion battery anodes made of polycrystalline graphite and identifying the degradation mechanisms that cause loss of electrochemical capacity. Understanding microstructural aspects of the graphite electrode degradation mechanisms during charging and discharging of Li-ion batteries is of key importance in order to design durable anodes with high capacity. An in-situ system was constructed using an electrochemical cell with an observation window, a large depth-of-field digital microscope and a micro-Raman spectrometer. It was revealed that electrode damage by removal of the surface graphite fragments of 5-10 mum size is the most intense during the first cycle that led to a drastic capacity drop. Once a solid electrolyte interphase (SEI) layer covered the electrode surface, the rate of graphite particle loss decreased. Yet, a gradual loss of capacity continued by the formation of interlayer cracks adjacent to SEI/graphite interfaces. Deposition of co-intercalation compounds, LiC6, Li2CO3 and Li2O, near the crack tips caused partial closure of propagating graphite cracks during cycling and reduced the crack growth rate. Bridging of crack faces by delaminated graphite layers also retarded crack propagation. The microstructure of the SEI layer, formed by electrochemical reduction of the ethylene carbonate based electrolyte, consisted of ˜5-20 nm sized crystalline domains (containing Li2CO3, Li2O 2 and nano-sized graphite fragments) dispersed in an amorphous matrix. During the SEI formation, two regimes of Li-ion diffusion were identified at the electrode/electrolyte interface depending on the applied voltage scan rate (dV/dt). A low Li-ion diffusion coefficient ( DLi+) at dV/dt < 0.05 mVs-1 produced a tubular SEI that uniformly covered the graphite surface and prevented damage at 25°C. At 60°C, a high D Li+ formed a Li2CO3-enriched SEI and ensued a 28% increase in the battery capacity at 25°C. On correlating the microscopic information to the electrochemical performance, novel Li2CO3-coated electrodes were fabricated that were durable. The SEI formed on pre-treated electrodes reduced the strain in the graphite lattice from 0.4% (for uncoated electrodes) to 0.1%, facilitated Li-ion diffusion and hence improved the capacity retention of Li-ion batteries during long-term cycling.

Tuning the Solid Electrolyte Interphase for Selective Li- and Na-Ion Storage in Hard Carbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soto, Fernando A.; Yan, Pengfei; Engelhard, Mark H.

Solid-electrolyte interphase (SEI) with controllable properties are highly desirable to improve battery performance. In this paper, we use a combined experimental and simulation approach to study the SEI formation on hard carbon in Li and Na-ion batteries. We show that with proper additives, stable SEI can be formed on hard carbon by pre-cycling the electrode materials in Li or Na-ion electrolyte. Detailed mechanistic studies suggest that the ion transport in the SEI layer is kinetically controlled and can be tuned by the applied voltage. Selective Na and Li-ion SEI membranes are produced using the Na or Li-ion based electrolytes respectively.more » The large Na ion SEI allows easy transport of Li ions, while the small Li ion SEI shuts off the Na-ion transport. Na-ion storage can be manipulated by tuning the SEI with film-forming electrolyte additives or preforming a SEI on the electrodes’ surface. The Na specific capacity can be controlled to <25 mAh/g, ~1/10 of the normal capacity (250 mAh/g). Unusual selective/preferential transport of Li-ion is demonstrated by preforming a SEI on the electrode’s surface and corroborated with a mixed electrolyte. This work may provide new guidance for preparing good ion selective conductors using electrochemical approaches in the future.« less

High performance red phosphorus electrode in ionic liquid-based electrolyte for Na-ion batteries

NASA Astrophysics Data System (ADS)

Dahbi, Mouad; Fukunishi, Mika; Horiba, Tatsuo; Yabuuchi, Naoaki; Yasuno, Satoshi; Komaba, Shinichi

2017-09-01

Electrochemical performance of the red phosphorus electrode was examined in ionic-liquid electrolyte, 0.25 mol dm-3 sodium bisfluorosulfonylamide (NaFSA) dissolved N-methyl-N-propylpyridinium-bisfluorosulfonylamide (MPPFSA), at room temperature. We compared its electrochemical performance to conventional EC/PC/DEC, EC/DEC, and PC solutions containing 1 mol dm-3 NaPF6. The electrode in NaFSA/MPPFSA demonstrated a reversible capacity of 1480 mAh g-1 and excellent capacity retention of 93% over 80 cycles, which is much better than those in the conventional electrolytes. The difference in capacity retention for the electrolytes correlates to the different solid electrolyte interphase (SEI) layer formed on the phosphorus electrode. To understand the SEI formation in NaFSA/MPPFSA and its evolution during cycling, we investigate the surface layer of the red phosphorus electrodes with hard X-ray photoelectron spectroscopy (HAXPES) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). A detailed analysis of HAXPES spectra demonstrates that SEI layer consists of major inorganic and minor organic species, originating from decomposition of MPP+ and FSA-. Homogenous surface layer is formed during the first cycle in NaFSA/MPPFSA while in alkyl carbonate ester electrolytes, continuous growth of surface film up to the 20th cycle is observed. Possibility of red phosphorous electrode for battery applications with pure ionic liquid is discussed.

Direct determination of solid-electrolyte interphase thickness and composition as a function of state of charge on a silicon anode

DOE PAGES

Veith, Gabriel M.; Doucet, Mathieu; Baldwin, J. K.; ...

2015-08-17

Using neutron reflectometry we have determined the thickness and chemistry of the solid-electrolyte interphase (SEI) layer grown on a silicon anode as a function of state of charge and during cycling. We show the chemistry of this SEI layer becomes more LiF like with increasing lithiation and more Li-C-O-F like with delithiation. More importantly the SEI layer thickness appears to increase (about 250 ) as the electrode becomes less lithiated and thins to 180 with increasing Li content (Li 3.7Si). We attribute this breathing to the continual consumption of electrolyte with cycling.

Separators for Li-Ion and Li-Metal Battery Including Ionic Liquid Based Electrolytes Based on the TFSI− and FSI− Anions

PubMed Central

Kirchhöfer, Marija; von Zamory, Jan; Paillard, Elie; Passerini, Stefano

2014-01-01

The characterization of separators for Li-ion or Li-metal batteries incorporating hydrophobic ionic liquid electrolytes is reported herein. Ionic liquids made of N-butyl-N-methylpyrrolidinium (PYR14+) or N-methoxyethyl-N-methylpyrrolidinium (PYR12O1+), paired with bis(trifluoromethanesulfonyl)imide (TFSI−) or bis(fluorosulfonyl)imide (FSI−) anions, were tested in combination with separators having different chemistries and morphologies in terms of wetting behavior, Gurley and McMullin number, as well as Li/(Separator + Electrolyte) interfacial properties. It is shown that non-functionalized microporous polyolefin separators are poorly wetted by FSI−-based electrolytes (contrary to TFSI−-based electrolytes), while the ceramic coated separator Separion® allows good wetting with all electrolytes. Furthermore, by comparing the lithium solid electrolyte interphase (SEI) resistance evolution at open circuit and during cycling, depending on separator morphologies and chemistries, it is possible to propose a scale for SEI forming properties in the order: PYR12O1FSI > PYR14FSI > PYR14TFSI > PYR12O1TFSI. Finally, the impact the separator morphology is evidenced by the SEI resistance evolution and by comparing Li electrodes cycled using separators with two different morphologies. PMID:25153637

The Electrochemical Performance of Silicon Nanoparticles in Concentrated Electrolyte.

PubMed

Chang, Zeng-Hua; Wang, Jian-Tao; Wu, Zhao-Hui; Gao, Min; Wu, Shuai-Jin; Lu, Shi-Gang

2018-06-11

Silicon is a promising material for anodes in energy-storage devices. However, excessive growth of a solid-electrolyte interphase (SEI) caused by the severe volume change during the (de)lithiation processes leads to dramatic capacity fading. Here, we report a super-concentrated electrolyte composed of lithium bis(fluorosulfonyl)imide (LiFSI) and propylene carbonate (PC) with a molar ratio of 1:2 to improve the cycling performance of silicon nanoparticles (SiNPs). The SiNP electrode shows a remarkably improved cycling performance with an initial delithiation capacity of approximately 3000 mAh g -1 and a capacity of approximately 2000 mAh g -1 after 100 cycles, exhibiting about 6.8 times higher capacity than the cells with dilute electrolyte LiFSI-(PC) 8 . Raman spectra reveal that most of the PC solvent and FSI anions are complexed by Li + to form a specific solution structure like a fluid polymeric network. The reduction of FSI anions starts to play an important role owing to the increased concentration of contact ion pairs (CIPs) or aggregates (AGGs), which contribute to the formation of a more mechanically robust and chemically stable complex SEI layer. The complex SEI layer can effectively suppress the morphology evolution of silicon particles and self-limit the excessive growth, which mitigates the crack propagation of the silicon electrode and the deterioration of the kinetics. This study will provide a new direction for screening cycling-stable electrolytes for silicon-based electrodes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Behavior of Lithium Metal Anodes under Various Capacity Utilization and High Current Density in Lithium Metal Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiao, Shuhong; Zheng, Jianming; Li, Qiuyan

Lithium (Li) metal batteries (LMBs) are regarded as the most promising power sources for electric vehicles. Besides the Li dendrite growth and low Li Coulombic efficiency, how to well match Li metal anode with a high loading (normally over 3.0 mAh cm-2) cathode is another key challenge to achieve the real high energy density battery. In this work, we systematically investigate the effects of the Li metal capacity usage in each cycle, manipulated by varying the cathode areal loading, on the stability of Li metal anode and the cycling performance of LMBs using the LiNi1/3Mn1/3Co1/3O2 (NMC) cathode and an additive-containingmore » dual-salt/carbonate-solvent electrolyte. It is demonstrated that the Li||NMC cells show decent long-term cycling performance even with NMC areal capacity loading up to ca. 4.0 mAh cm-2 and at a charge current density of 1.0 mA cm-2. The increase of the Li capacity usage in each cycle causes variation in the components of the solid electrolyte interphase (SEI) layer on Li metal anode and generates more ionic conductive species from this electrolyte. Further study reveals for the first time that the degradation of Li metal anode and the thickness of SEI layer on Li anode show linear relationship with the areal capacity of NMC cathode. Meanwhile, the expansion rate of consumed Li and the ratio of SEI thickness to NMC areal loading are kept almost the same value with increasing cathode loading, respectively. These fundamental findings provide new perspectives on the rational evaluation of Li metal anode stability for the development of rechargeable LMBs.« less

A structural study of solid electrolyte interface on negative electrode of lithium-Ion battery by electron microscopy.

PubMed

Matsushita, Tadashi; Watanabe, Jiro; Nakao, Tatsuya; Yamashita, Seiichi

2014-11-01

For the last decades, the performance of the lithium-ion battery (LIB) has been significantly improved and its applications have been expanding rapidly. However, its performance has yet to be enhanced.In the lithium-ion battery development, it is important to elucidate the electrode structure change in detail during the charge and discharge cycling. In particular, solid electrolyte interface (SEI) formed by decomposition of the electrolytes on the graphite negative electrode surface should play an important role for battery properties. Therefore, it is essential to control the structure and composition of SEI to improve the battery performance. Here, we conducted a scanning electron microscope (SEM) and transmission electron microscope (TEM) study to elucidate the structures of the SEI during the charge and discharge process using LiNi1/3Co1/3Mn1/3O2 [1] cathode and graphite anode. [2] Since SEI is a lithium-containing compound with high activity, it was observed without being exposed to the atmosphere. The electrodes including SEI were sampled after dismantling batteries with cutoff voltages of 3V and 4.2V for the charge process and 3V for the discharge process. Fig.1 shows SEM images of the graphite electrode surface during the charge and discharge process. The change of the SEI structure during the process was clearly observed. Further, TEM images showed that the SEI grew thicker during the charge process and becomes thinner when discharged. These results with regard to the reversible SEI structure could give a new insight for the battery development.jmicro;63/suppl_1/i21/DFU056F1F1DFU056F1Fig. 1.SEM images of the graphite electrode surface:(a) before charge process;(b) with charge-cutoff voltage of 3.0V; (c) with charge-cutoff voltage of 4.2V; (d) with discharge-cutoff voltage of 3.0V. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A rechargeable Li-O2 battery using a lithium nitrate/N,N-dimethylacetamide electrolyte.

PubMed

Walker, Wesley; Giordani, Vincent; Uddin, Jasim; Bryantsev, Vyacheslav S; Chase, Gregory V; Addison, Dan

2013-02-13

A major challenge in the development of rechargeable Li-O(2) batteries is the identification of electrolyte materials that are stable in the operating environment of the O(2) electrode. Straight-chain alkyl amides are one of the few classes of polar, aprotic solvents that resist chemical degradation in the O(2) electrode, but these solvents do not form a stable solid-electrolyte interphase (SEI) on the Li anode. The lack of a persistent SEI leads to rapid and sustained solvent decomposition in the presence of Li metal. In this work, we demonstrate for the first time successful cycling of a Li anode in the presence of the solvent, N,N-dimethylacetamide (DMA), by employing a salt, lithium nitrate (LiNO(3)), that stabilizes the SEI. A Li-O(2) cell containing this electrolyte composition is shown to cycle for more than 2000 h (>80 cycles) at a current density of 0.1 mA/cm(2) with a consistent charging profile, good capacity retention, and O(2) detected as the primary gaseous product formed during charging. The discovery of an electrolyte system that is compatible with both electrodes in a Li-O(2) cell may eliminate the need for protecting the anode with a ceramic membrane.

Modulation of solid electrolyte interphase of lithium-ion batteries by LiDFOB and LiBOB electrolyte additives

NASA Astrophysics Data System (ADS)

Huang, Shiqiang; Wang, Shuwei; Hu, Guohong; Cheong, Ling-Zhi; Shen, Cai

2018-05-01

Solid-electrolyte interphase (SEI) layer is an organic-inorganic composite layer that allows Li+ transport across but blocks electron flow across and prevents solvent diffusing to electrode surface. Morphology, thickness, mechanical and chemical properties of SEI are important for safety and cycling performance of lithium-ion batteries. Herein, we employ a combination of in-situ AFM and XPS to investigate the effects of two electrolyte additives namely lithium difluoro(oxalate)borate (LiDFOB) and lithium bis(oxalato)borate (LiBOB) on SEI layer. LiDFOB is found to result in a thin but hard SEI layer containing more inorganic species (LiF and LiCO3); meanwhile LiBOB promotes formation of a thick but soft SEI layer containing more organic species such as ROCO2Li. Findings from present study will help development of electrolyte additives that promote formation of good SEI layer.

Multinuclear NMR Study of the Solid Electrolyte Interface Formed in Lithium Metal Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wan, Chuan; Xu, Suochang; Hu, Mary Y.

The composition of the solid electrolyte interphase (SEI) layers associated with a high performance Cu|Li cell using lithium bis(fluorosulfonyi)imide (LiFSI) in 1,2-dimethoxyethane (DME) as electrolyte is determined by a multinuclear (6Li, 19F, 13C and 1H) solid-state MAS NMR study at high magnetic field (850 MHz). This cell can be cycled at high rates (4 mA•cm-2) for more than 1000 cycles with no increase in the cell impedance at high Columbic efficiency (average of 98.4%) in a highly concentrated LiFSI-DME electrolyte (4 M). LiFSI, LiF, Li2O2 (and/or CH3OLi), LiOH, Li2S and Li2O are observed in the SEI and validated by comparingmore » with the spectra acquired on standard compounds and literature reports. To gain further insight into the role of the solute and its concentration dependence on the formation of SEIs while keeping the solvent of DME unchanged, the SEIs from different concentrations of LiFSI-DME and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)-DME electrolyte are also investigated. It is found that LiF, a lithiated compound with superior mechanical strength and good Li+ ionic conductivity, is observed in the concentrated 4.0 M LiFSI-DME and the 3.0 M LiTFSI-DME systems but not in the diluted 1.0 M LiFSI-DME system. Li2O exists in both low and high concentration of LiFSI-DME while no Li2O is observed in the LiTFSI system. Furthermore, the dead metallic Li is reduced in the 4 M LiFSI-DME system compared with that in the 1 M LiFSI-DME system. Quantitative 6Li MAS results indicate that the SEI associated with the 4 M LiFSI-DEME is denser or thicker than that of the 1 M LiFSI-DME and the 3 M LiTFSI-DME systems. These findings are likely the reasons for explaining the high electrochemical performance associated with the high concentration LiFSI-DME system.« less

Electrochemical performance and interfacial investigation on Si composite anode for lithium ion batteries in full cell

NASA Astrophysics Data System (ADS)

Shobukawa, Hitoshi; Alvarado, Judith; Yang, Yangyuchen; Meng, Ying Shirley

2017-08-01

Lithium ion batteries (LIBs) containing silicon (Si) as a negative electrode have gained much attention recently because they deliver high energy density. However, the commercialization of LIBs with Si anode is limited due to the unstable electrochemical performance associated with expansion and contraction during electrochemical cycling. This study investigates the electrochemical performance and degradation mechanism of a full cell containing Si composite anode and LiFePO4 (lithium iron phosphate (LFP)) cathode. Enhanced electrochemical cycling performance is observed when the full cell is cycled with fluoroethylene carbonate (FEC) additive compared to the standard electrolyte. To understand the improvement in the electrochemical performance, x-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) are used. Based on the electrochemical behavior, FEC improves the reversibility of lithium ion diffusion into the solid electrolyte interphase (SEI) on the Si composite anode. Moreover, XPS analysis demonstrates that the SEI composition generated from the addition of FEC consists of a large amount of LiF and less carbonate species, which leads to better capacity retention over 40 cycles. The effective SEI successively yields more stable capacity retention and enhances the reversibility of lithium ion diffusion through the interphase of the Si anode, even at higher discharge rate. This study contributes to a basic comprehension of electrochemical performance and SEI formation of LIB full cells with a high loading Si composite anode.

Simultaneous Formation of Artificial SEI Film and 3D Host for Stable Metallic Sodium Anodes.

PubMed

Zhang, Di; Li, Bin; Wang, Shuai; Yang, Shubin

2017-11-22

Metallic sodium is a promising anode for sodium-based batteries, owing to its high theoretical capacity (1165 mAh g -1 ) and low potential (-2.714 V vs standard hydrogen electrode). However, the growth of sodium dendrites and the infinite volume change of metallic sodium during sodium striping/plating result in a low Coulombic efficiency and poor cycling stability, generating a safety hazard of sodium-based batteries. Here, an efficient approach was proposed to simultaneously generate an artificial SEI film and 3D host for metallic sodium based on a conversion reaction (CR) between sodium and MoS 2 (4Na + MoS 2 = 2Na 2 S + Mo) at room temperature. In the resultant sodium-MoS 2 hybrid after the conversion reaction (Na-MoS 2 (CR)), the production Na 2 S is homogeneously dispersed on the surface of metallic sodium, which can act as an artificial SEI film, efficiently preventing the growth of sodium dendrites; the residual MoS 2 nanosheets can construct a 3D host to confine metallic sodium, accommodating largely the volume change of sodium. Consequently, the Na-MoS 2 (CR) hybrid exhibits very low overpotential of 25 mV and a very long cycle stability more than 1000 cycles. This novel strategy is promising to promote the development of metal (lithium, sodium, zinc)-based electrodes.

Artificial Solid Electrolyte Interphase-Protected LixSi Nanoparticles: An Efficient and Stable Prelithiation Reagent for Lithium-Ion Batteries.

PubMed

Zhao, Jie; Lu, Zhenda; Wang, Haotian; Liu, Wei; Lee, Hyun-Wook; Yan, Kai; Zhuo, Denys; Lin, Dingchang; Liu, Nian; Cui, Yi

2015-07-08

Prelithiation is an important strategy to compensate for lithium loss in lithium-ion batteries, particularly during the formation of the solid electrolyte interphase (SEI) from reduced electrolytes in the first charging cycle. We recently demonstrated that LixSi nanoparticles (NPs) synthesized by thermal alloying can serve as a high-capacity prelithiation reagent, although their chemical stability in the battery processing environment remained to be improved. Here we successfully developed a surface modification method to enhance the stability of LixSi NPs by exploiting the reduction of 1-fluorodecane on the LixSi surface to form a continuous and dense coating through a reaction process similar to SEI formation. The coating, consisting of LiF and lithium alkyl carbonate with long hydrophobic carbon chains, serves as an effective passivation layer in the ambient environment. Remarkably, artificial-SEI-protected LixSi NPs show a high prelithiation capacity of 2100 mA h g(-1) with negligible capacity decay in dry air after 5 days and maintain a high capacity of 1600 mA h g(-1) in humid air (∼10% relative humidity). Silicon, tin, and graphite were successfully prelithiated with these NPs to eliminate the irreversible first-cycle capacity loss. The use of prelithiation reagents offers a new approach to realize next-generation high-energy-density lithium-ion batteries.

Active Mechanism of the Interphase Film-Forming Process for an Electrolyte Based on a Sulfolane Solvent and a Chelato-Borate Complexe.

PubMed

Li, Chunlei; Wang, Peng; Li, Shiyou; Zhao, Dongni; Zhao, Qiuping; Liu, Haining; Cui, Xiao-Ling

2018-06-14

Electrolytes based on sulfolane (SL) solvents and lithium bis(oxalato)borate (LiBOB) chelato-borate complexes have been reported many times for use in advanced lithium-ion batteries due to their many advantages. This study aims to clarify the active mechanism of the interphase film-forming process to optimize the properties of these batteries by experimental analysis and theoretical calculations. The results indicate that the self-repairing film-forming process during the first cycle is divided into three stages: the initial film formation with an electric field force of ~1.80 V, the further growth of the preformation solid electrolyte interface (SEI) film at ~1.73 V, and the final formation of a complete SEI film at a potential below 0.7 V. Additionally, we can deduce that the decomposition of LiBOB and SL occurs throughout nearly the entire process of the formation of the SEI film. The decomposition product of BOB- anions tends to form films with an irregular structure, while the decomposition product of SL is in favor of the formation of a uniform SEI film.

Capacity Fading Mechanisms of Silicon Nanoparticle Negative Electrodes for Lithium Ion Batteries

DOE PAGES

Yoon, Taeho; Nguyen, Cao Cuong; Seo, Daniel M.; ...

2015-09-16

A thorough analysis of the evolution of the voltage profiles of silicon nanoparticle electrodes upon cycling has been conducted. The largest changes to the voltage profiles occur at the earlier stages (> 0.16 V vs Li/Li +) of lithiation of the silicon nanoparticles. The changes in the voltage profiles suggest that the predominant failure mechanism of the silicon electrode is related to incomplete delithiation of the silicon electrode during cycling. The incomplete delithiation is attributed to resistance increases during delithiation, which are predominantly contact and solid electrolyte interface (SEI) resistance. The capacity retention can be significantly improved by lowering delithiationmore » cutoff voltage or by introducing electrolyte additives, which generate a superior SEI. The improved capacity retention is attributed to the reduction of the contact and SEI resistance.« less

Multistage Mechanism of Lithium Intercalation into Graphite Anodes in the Presence of the Solid Electrolyte Interface.

PubMed

Dinkelacker, Franz; Marzak, Philipp; Yun, Jeongsik; Liang, Yunchang; Bandarenka, Aliaksandr S

2018-04-25

A so-called solid electrolyte interface (SEI) in a lithium-ion battery largely determines the performance of the whole system. However, it is one of the least understood objects in these types of batteries. SEIs are formed during the initial charge-discharge cycles, prevent the organic electrolytes from further decomposition, and at the same time govern lithium intercalation into the graphite anodes. In this work, we use electrochemical impedance spectroscopy and atomic force microscopy to investigate the properties of a SEI film and an electrified "graphite/SEI/electrolyte interface". We reveal a multistage mechanism of lithium intercalation and de-intercalation in the case of graphite anodes covered by SEI. On the basis of this mechanism, we propose a relatively simple model, which perfectly explains the impedance response of the "graphite/SEI/electrolyte" interface at different temperatures and states of charge. From the whole data obtained in this work, it is suggested that not only Li + but also negatively charged species, such as anions from the electrolyte or functional groups of the SEI, likely interact with the surface of the graphite anode.

Coordinated Expression of Cyclin-dependent Kinase-4 and its Regulators in Human Oral Tumors

PubMed Central

POI, MING J.; KNOBLOCH, THOMAS J.; SEARS, MARTA T.; UHRIG, LANA K.; WARNER, BLAKE M.; WEGHORST, CHRISTOPHER M.; LI, JUNAN

2014-01-01

Background/Aim While aberrant expression of cyclin-dependent kinase-4 (CDK4) has been found in squamous cell carcinoma of the head and neck (SCCHN), the associations between CDK4 and its regulators, namely, cyclin D1, cyclin E, gankyrin, SEI1, and BMI1 in gene expression remain to be explored. Herein we investigated the mRNA profiles of these oncogenes and their interrelations in different oral lesion tissues. Materials and Methods Thirty SCCHN specimens and patient-matched high at-risk mucosa (HARM) and 16 healthy control specimens were subjected to quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analyses. Results The mRNA levels of CDK4, cyclin D1, gankyrin, SEI1, BMI1 were significantly elevated in both HARM and SCCHN (in comparison with control specimens), and statistically significant correlations were found among these markers in gene expression. Conclusion Up-regulation of CDK4 and its regulators takes place in oral cancer progression in a coordinate manner, and HARM and SCCHN share a similar molecular signature within the CDK4-pRB pathway. PMID:24982332

Integrating Software-Architecture-Centric Methods into the Rational Unified Process

DTIC Science & Technology

2004-07-01

Architecture Design ...................................................................................... 19...QAW in a life- cycle context. One issue that needs to be addressed is how scenarios produced in a QAW can be used by a software architecture design method...implementation testing. 18 CMU/SEI-2004-TR-011 CMU/SEI-2004-TR-011 19 4 Architecture Design The Attribute-Driven Design (ADD) method

A stable lithiated silicon-chalcogen battery via synergetic chemical coupling between silicon and selenium.

PubMed

Eom, KwangSup; Lee, Jung Tae; Oschatz, Martin; Wu, Feixiang; Kaskel, Stefan; Yushin, Gleb; Fuller, Thomas F

2017-01-05

Li-ion batteries dominate portable energy storage due to their exceptional power and energy characteristics. Yet, various consumer devices and electric vehicles demand higher specific energy and power with longer cycle life. Here we report a full-cell battery that contains a lithiated Si/graphene anode paired with a selenium disulfide (SeS 2 ) cathode with high capacity and long-term stability. Selenium, which dissolves from the SeS 2 cathode, was found to become a component of the anode solid electrolyte interphase (SEI), leading to a significant increase of the SEI conductivity and stability. Moreover, the replacement of lithium metal anode impedes unwanted side reactions between the dissolved intermediate products from the SeS 2 cathode and lithium metal and eliminates lithium dendrite formation. As a result, the capacity retention of the lithiated silicon/graphene-SeS 2 full cell is 81% after 1,500 cycles at 268 mA g SeS2 -1 . The achieved cathode capacity is 403 mAh g SeS2 -1 (1,209 mAh cm SeS2 -3 ).

Phosphorus Enrichment as a New Composition in the Solid Electrolyte Interphase of High-Voltage Cathodes and Its Effects on Battery Cycling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Pengfei; Zheng, Jianming; Kuppan, Saravanan

2015-11-10

Immersion of a solid into liquid often leads to the modification of both the structure and chemistry of surface of the solid, which subsequently affects the chemical and physical properties of the system. For the case of the rechargeable lithium ion battery, such a surface modification is termed as solid electrolyte interphase (SEI) layer, which has been perceived to play critical role for the stable operation of the batteries. However, the structure and chemical composition of SEI layer and its spatial distribution and dependence on the battery operating condition remain unclear. By using aberration corrected scanning transmission electron microscopy coupledmore » with ultra-high sensitive energy dispersive x-ray spectroscopy, we probed the structure and chemistry of SEI layer on several high voltage cathodes. We show that layer-structured cathodes, when cycled at a high cut off voltage, can form a P-rich SEI layer on their surface, which is a direct evidence of Li-salt (LiPF6) decomposition. Our systematical investigations indicate such cathode/Li-salt side reaction shows strong dependence on structure of the cathode materials, operating voltage and temperature, indicating the feasibility of SEI engineering. These findings provide us valuable insights into the complex interface between the high-voltage cathode and the electrolyte.« less

Surface and interface engineering of anatase TiO2 anode for sodium-ion batteries through Al2O3 surface modification and wise electrolyte selection

NASA Astrophysics Data System (ADS)

Li, Tao; Gulzar, Umair; Bai, Xue; Monaco, Simone; Longoni, Gianluca; Prato, Mirko; Marras, Sergio; Dang, Zhiya; Capiglia, Claudio; Proietti Zaccaria, Remo

2018-04-01

In the present study, Al2O3 is utilized for the first time as coating agent on nanostructured anatase TiO2 in order to investigate its effect on sodium-ion batteries performance. Our results show that the Al2O3 coating, introduced by a facile two-step approach, provides beneficial effects to the TiO2-based anodes. However, the coated TiO2 still suffers of capacity fading upon cycling when using 1.0 M of NaClO4 in propylene carbonate (PC) as electrolyte. To address this issue, the influence of different electrolytes (NaClO4 salt in various solvents) is further studied. It is found that the modified TiO2 exhibits significant improvements in cycling performance using binary ethylene carbonate (EC) and PC solvent mixture without the need of the commonly used fluoroethylene carbonate (FEC) additive. Under the best configuration, our battery could deliver a high reversible capacity of 188.1 mAh g-1 at 0.1C after 50 cycles, good rate capability up to 5C, and remarkable long-term cycling stability at 1C rate for 650 cycles. This excellent performance can be ascribed to the synergistic effects of surface and interface engineering enabling the formation of a stable and highly ionic conductive interface layer in EC:PC based electrolyte which combines the native SEI film and an 'artificial' SEI layer of irreversibly formed Na-Al-O.

Bubble-Sheet-Like Interface Design with an Ultrastable Solid Electrolyte Layer for High-Performance Dual-Ion Batteries.

PubMed

Qin, Panpan; Wang, Meng; Li, Na; Zhu, Haili; Ding, Xuan; Tang, Yongbing

2017-05-01

In this work, a bubble-sheet-like hollow interface design on Al foil anode to improve the cycling stability and rate performance of aluminum anode based dual-ion battery is reported, in which, a carbon-coated hollow aluminum anode is used as both anode materials and current collector. This anode structure can guide the alloying position inside the hollow nanospheres, and also confine the alloy sizes within the hollow nanospheres, resulting in significantly restricted volumetric expansion and ultrastable solid electrolyte interface (SEI). As a result, the battery demonstrates an excellent long-term cycling stability within 1500 cycles with ≈99% capacity retention at 2 C. Moreover, this cell displays an energy density of 169 Wh kg -1 even at high power density of 2113 W kg -1 (10 C, charge and discharge within 6 min), which is much higher than most of conventional lithium ion batteries. The interfacial engineering strategy shown in this work to stabilize SEI layer and control the alloy forming position could be generalized to promote the research development of metal anodes based battery systems. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Auger Electrons as Probes for Composite Micro- and Nano- structured Materials: Application to Solid Electrolyte Interphases in Graphite and Silicon-Graphite Electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalaga, Kaushik; Shkrob, Ilya A.; Haasch, Richard T.

In this study, Auger electron spectroscopy (AES) combined with ion sputtering profilometry, Xray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) have been used in a complementary fashion to examine chemical and microstructural changes in graphite (Gr) and silicon/graphite (Si/Gr) blends contained in the negative electrodes of lithium-ion cells. We demonstrate how AES can be used to characterize morphology of the solid-electrolyte interphase (SEI) deposits in such heterogeneous media, complementing well-established methods, such as XPS and SEM. In this way we demonstrate that the SEI does not consist of uniformly thick layers on the graphite and silicon; the thickness ofmore » the SEI layers in cycle-life aged electrodes follows an exponential distribution with a mean of ca. 13 nm for the graphite and ca. 20-25 nm for the silicon nanoparticles (with a crystalline core of 50-70 nm in diameter). Furthermore, a “sticky-sphere” model, in which Si nanoparticles are covered with a layer of polymer binder (that is replaced by the SEI during cycling) of variable thickness is introduced to account for the features observed.« less

Auger Electrons as Probes for Composite Micro- and Nano- structured Materials: Application to Solid Electrolyte Interphases in Graphite and Silicon-Graphite Electrodes

DOE PAGES

Kalaga, Kaushik; Shkrob, Ilya A.; Haasch, Richard T.; ...

2017-10-05

In this study, Auger electron spectroscopy (AES) combined with ion sputtering profilometry, Xray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) have been used in a complementary fashion to examine chemical and microstructural changes in graphite (Gr) and silicon/graphite (Si/Gr) blends contained in the negative electrodes of lithium-ion cells. We demonstrate how AES can be used to characterize morphology of the solid-electrolyte interphase (SEI) deposits in such heterogeneous media, complementing well-established methods, such as XPS and SEM. In this way we demonstrate that the SEI does not consist of uniformly thick layers on the graphite and silicon; the thickness ofmore » the SEI layers in cycle-life aged electrodes follows an exponential distribution with a mean of ca. 13 nm for the graphite and ca. 20-25 nm for the silicon nanoparticles (with a crystalline core of 50-70 nm in diameter). Furthermore, a “sticky-sphere” model, in which Si nanoparticles are covered with a layer of polymer binder (that is replaced by the SEI during cycling) of variable thickness is introduced to account for the features observed.« less

Poly(isobutylene-alt-maleic anhydride) binders containing lithium for high-performance Li-ion batteries

NASA Astrophysics Data System (ADS)

Ku, Jun-Hwan; Hwang, Seung-Sik; Ham, Dong-Jin; Song, Min-Sang; Shon, Jeong-Kuk; Ji, Sang-Min; Choi, Jae-Man; Doo, Seok-Gwang

2015-08-01

Anode materials including graphite are known to be thermodynamically unstable toward organic solvents and salts and become covered by a passivating film (Solid electrolyte interphase, SEI) which retards the kinetics because of the high electronic resistivity. To achieve high performance in lithium ion batteries (LIBs), the SEIs are required to be mechanically stable during repeated cycling and possess highly ion-conductive. In this work, we have investigated an artificial pre-SEI on graphite electrode using a polymer binder containing lithium (i.e., a Li-copolymer of isobutylene and maleic anhydride, Li-PIMA) and its effect on the anode performances. During charging, the polymer binder with the functional group (-COOLi) acts as a SEI component, reducing the electrolyte decomposition and providing a stable passivating layer for the favorable penetration of lithium ions. Hence, by using the binder containing lithium, we have been able to obtain the first Coulombic efficiency of 84.2% (compared to 77.2% obtained using polyvinylidene fluoride as the binder) and a capacity retention of 99% after 100 cycles. The results of our study demonstrate that binder containing lithium we have used is a favorable candidate for the development of high-performance LIBs.

Density Functional Theory Research into the Reduction Mechanism for the Solvent/Additive in a Sodium-Ion Battery.

PubMed

Liu, Qi; Mu, Daobin; Wu, Borong; Wang, Lei; Gai, Liang; Wu, Feng

2017-02-22

The solid-electrolyte interface (SEI) film in a sodium-ion battery is closely related to capacity fading and cycling stability of the battery. However, there are few studies on the SEI film of sodium-ion batteries and the mechanism of SEI film formation is unclear. The mechanism for the reduction of ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), ethylene sulfite (ES), 1,3-propylene sulfite (PS), and fluorinated ethylene carbonate (FEC) is studied by DFT. The reaction activation energies, Gibbs free energies, enthalpies, and structures of the transition states are calculated. It is indicated that VC, ES, and PS additives in the electrolyte are all easier to form organic components in the anode SEI film by one-electron reduction. The priority of one-electron reduction to produce organic SEI components is in the order of VC>PC>EC; two-electron reduction to produce the inorganic Na 2 CO 3 component is different and follows the order of EC>PC>VC. Two-electron reduction for sulfites ES and PS to form inorganic Na 2 SO 3 is harder than that of carbonate ester reduction. It is also suggested that the one- and two-electron reductive decomposition pathway for FEC is more feasible to produce inorganic NaF components. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The design of a Li-ion full cell battery using a nano silicon and nano multi-layer graphene composite anode

NASA Astrophysics Data System (ADS)

Eom, KwangSup; Joshi, Tapesh; Bordes, Arnaud; Do, Inhwan; Fuller, Thomas F.

2014-03-01

In this study, a Si-graphene composite, which is composed of nano Si particles and nano-sized multi-layer graphene particles, and micro-sized multi-layer graphene plate conductor, was used as the anode for Li-ion battery. The Si-graphene electrode showed the high capacity and stable cyclability at charge/discharge rate of C/2 in half cell tests. Nickel cobalt aluminum material (NCA) was used as a cathode in the full cell to evaluate the practicality of the new Si-graphene material. Although the Si-graphene anode has more capacity than the NCA cathode in this designed full cell, the Si-graphene anode had a greater effect on the full-cell performance due to its large initial irreversible capacity loss and continuous SEI formation during cycling. When fluoro-ethylene carbonate was added to the electrolyte, the cyclability of the full cell was much improved due to less SEI formation, which was confirmed by the decreases in the 1st irreversible capacity loss, overpotential for the 1st lithiation, and the resistance of the SEI.

Understanding electrical conduction in lithium ion batteries through multi-scale modeling

NASA Astrophysics Data System (ADS)

Pan, Jie

Silicon (Si) has been considered as a promising negative electrode material for lithium ion batteries (LIBs) because of its high theoretical capacity, low discharge voltage, and low cost. However, the utilization of Si electrode has been hampered by problems such as slow ionic transport, large stress/strain generation, and unstable solid electrolyte interphase (SEI). These problems severely influence the performance and cycle life of Si electrodes. In general, ionic conduction determines the rate performance of the electrode, while electron leakage through the SEI causes electrolyte decomposition and, thus, causes capacity loss. The goal of this thesis research is to design Si electrodes with high current efficiency and durability through a fundamental understanding of the ionic and electronic conduction in Si and its SEI. Multi-scale physical and chemical processes occur in the electrode during charging and discharging. This thesis, thus, focuses on multi-scale modeling, including developing new methods, to help understand these coupled physical and chemical processes. For example, we developed a new method based on ab initio molecular dynamics to study the effects of stress/strain on Li ion transport in amorphous lithiated Si electrodes. This method not only quantitatively shows the effect of stress on ionic transport in amorphous materials, but also uncovers the underlying atomistic mechanisms. However, the origin of ionic conduction in the inorganic components in SEI is different from that in the amorphous Si electrode. To tackle this problem, we developed a model by separating the problem into two scales: 1) atomistic scale: defect physics and transport in individual SEI components with consideration of the environment, e.g., LiF in equilibrium with Si electrode; 2) mesoscopic scale: defect distribution near the heterogeneous interface based on a space charge model. In addition, to help design better artificial SEI, we further demonstrated a theoretical design of multicomponent SEIs by utilizing the synergetic effect found in the natural SEI. We show that the electrical conduction can be optimized by varying the grain size and volume fraction of two phases in the artificial multicomponent SEI.

A stable lithiated silicon–chalcogen battery via synergetic chemical coupling between silicon and selenium

PubMed Central

Eom, KwangSup; Lee, Jung Tae; Oschatz, Martin; Wu, Feixiang; Kaskel, Stefan; Yushin, Gleb; Fuller, Thomas F.

2017-01-01

Li-ion batteries dominate portable energy storage due to their exceptional power and energy characteristics. Yet, various consumer devices and electric vehicles demand higher specific energy and power with longer cycle life. Here we report a full-cell battery that contains a lithiated Si/graphene anode paired with a selenium disulfide (SeS2) cathode with high capacity and long-term stability. Selenium, which dissolves from the SeS2 cathode, was found to become a component of the anode solid electrolyte interphase (SEI), leading to a significant increase of the SEI conductivity and stability. Moreover, the replacement of lithium metal anode impedes unwanted side reactions between the dissolved intermediate products from the SeS2 cathode and lithium metal and eliminates lithium dendrite formation. As a result, the capacity retention of the lithiated silicon/graphene—SeS2 full cell is 81% after 1,500 cycles at 268 mA gSeS2−1. The achieved cathode capacity is 403 mAh gSeS2−1 (1,209 mAh cmSeS2−3). PMID:28054543

High-temperature solid electrolyte interphases (SEI) in graphite electrodes

NASA Astrophysics Data System (ADS)

Rodrigues, Marco-Tulio F.; Sayed, Farheen N.; Gullapalli, Hemtej; Ajayan, Pulickel M.

2018-03-01

Thermal fragility of the solid electrolyte interphase (SEI) is a major source of performance decay in graphite anodes, and efforts to overcome the issues offered by extreme environments to Li-ion batteries have had limited success. Here, we demonstrate that the SEI can be extensively reinforced by carrying the formation cycles at elevated temperatures. Under these conditions, decomposition of the ionic liquid present in the electrolyte favored the formation of a thicker and more protective layer. Cells in which the solid electrolyte interphase was cast at 90 °C were significantly less prone to self-discharge when exposed to high temperature, with no obvious damages to the formed SEI. This additional resilience was accomplished at the expense of rate capability, as charge transfer became growingly inefficient in these systems. At slower rates, however, cells that underwent SEI formation at 90 °C presented superior performances, as a result of improved Li+ transport through the SEI, and optimal wetting of graphite by the electrolyte. This work analyzes different graphite hosts and ionic liquids, showing that this effect is more pervasive than anticipated, and offering the unique perspective that, for certain systems, temperature can actually be an asset for passivation.

A self-cleaning Li-S battery enabled by a bifunctional redox mediator

NASA Astrophysics Data System (ADS)

Ren, Y. X.; Zhao, T. S.; Liu, M.; Zeng, Y. K.; Jiang, H. R.

2017-09-01

The polysulfide shuttle effect and lithium dendrite growth in lithium-sulfur (Li-S) batteries can repeatedly breach the anodic solid electrolyte interphase (SEI) over cycling. As a result, irreversible short-chain sulfide side products (Li2Sx, x = 1, 2) keep depositing on the Li anode, leading to the active material loss, increasing the Li+ transport resistance, and thereby reducing the cycle life. In this work, indium iodide (InI3) is investigated as a bifunctional electrolyte additive for Li-S batteries to protect the Li anode and decompose the side products spontaneously. On the one hand, Indium (In) is electrodeposited onto the Li anode prior to Li plating during the initial charging process, forming a chemically and mechanically stable SEI to prevent the Li anode from reacting with soluble polysulfide species to form Li2Sx (x = 1, 2) side products. On the other hand, by adequately overcharging the battery, the triiodide/iodide redox mediator is capable of chemically transforming side products deposited on the Li anode and separator into soluble polysulfides, which can be recycled by the cathode. It is shown that the battery with the InI3 additive exhibits a prolonged cycle life, and is capable of retrieving its capacity by a facile overcharging process.

Highly Stable Lithium Metal Batteries Enabled by Regulating the Solvation of Lithium Ions in Nonaqueous Electrolytes.

PubMed

Zhang, Xue-Qiang; Chen, Xiang; Cheng, Xin-Bing; Li, Bo-Quan; Shen, Xin; Yan, Chong; Huang, Jia-Qi; Zhang, Qiang

2018-05-04

Safe and rechargeable lithium metal batteries have been difficult to achieve because of the formation of lithium dendrites. Herein an emerging electrolyte based on a simple solvation strategy is proposed for highly stable lithium metal anodes in both coin and pouch cells. Fluoroethylene carbonate (FEC) and lithium nitrate (LiNO 3 ) were concurrently introduced into an electrolyte, thus altering the solvation sheath of lithium ions, and forming a uniform solid electrolyte interphase (SEI), with an abundance of LiF and LiN x O y on a working lithium metal anode with dendrite-free lithium deposition. Ultrahigh Coulombic efficiency (99.96 %) and long lifespans (1000 cycles) were achieved when the FEC/LiNO 3 electrolyte was applied in working batteries. The solvation chemistry of electrolyte was further explored by molecular dynamics simulations and first-principles calculations. This work provides insight into understanding the critical role of the solvation of lithium ions in forming the SEI and delivering an effective route to optimize electrolytes for safe lithium metal batteries. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

IEEE Computer Society/Software Engineering Institute Software Process Achievement (SPA) Award 2009

DTIC Science & Technology

2011-03-01

capabilities to our GDM. We also introduced software as a service ( SaaS ) as part our technology solutions and have further enhanced our ability to...model PROSPER Infosys production support methodology Q&P quality and productivity R&D research and development SaaS software as a service ... Software Development Life Cycle (SDLC) 23 Table 10: Scientific Estimation Coverage by Service Line 27 CMU/SEI-2011-TR-008 | vi CMU/SEI-2011

Comparative study of imide-based Li salts as electrolyte additives for Li-ion batteries

NASA Astrophysics Data System (ADS)

Sharova, Varvara; Moretti, Arianna; Diemant, Thomas; Varzi, Alberto; Behm, R. Jürgen; Passerini, Stefano

2018-01-01

Herein, we report the results of a detailed study on the use of different Li imide salts (LiTFSI, LiFSI, and LiFTFSI) as electrolyte additives for lithium-ion batteries. The introduction of lithium imide salts in the electrolyte is shown to considerably improve the first cycle coulombic efficiency and the long-term cycling stability of graphite/LiFePO4 cells. Using LiTFSI, a capacity fading of only ∼2% occurred over 600 cycles while the control cell with the state-of-the-art additive (VC) lost ∼20% of the initial capacity at 20 °C. The results of the XPS and impedance spectroscopy measurements of graphite electrodes show that, after the formation cycle, the SEI obtained in the presence of imide salts is thinner, contains more LiF and is less resistive than that obtained using VC. Despite the beneficial effect of the imide salts on the lithium-ion cell performance, a slightly reduced thermal stability of the SEI is observed.

Synthesis and mode of action studies of N-[(-)-jasmonyl]-S-tyrosin and ester seiridin jasmonate.

PubMed

Reveglia, Pierluigi; Chini, Andrea; Mandoli, Alessandro; Masi, Marco; Cimmino, Alessio; Pescitelli, Gennaro; Evidente, Antonio

2018-03-01

Recent analyses on fungal jasmonic acid (JA)-containing metabolites suggest a mode-of-action of these naturally occurring compounds as inactive storage pools of JA. Plants and/or fungi can catabolize JA into the bioactive jasmonyl-isoleucine (JA-Ile) that in turn activates the JA-Ile-pathway in planta. To extend our knowledge on JA-derivates related to natural occurring JA conjugates, N-[(-)-jasmonyl]-S-tyrosin (JA-Tyr) and the ester JA-Sei between JA and seiridin, a fungal disubstituted furanone, were synthesized. The classical procedures for ester synthesis were applied for compound JA-Sei, while N-[(-)-jasmonyl]-S-tyrosin was synthesized with an optimized procedure. JA-Tyr and JA-Sei were characterized by spectroscopic method (essentially 1D and 2D NMR spectroscopy and ESI-MS) and their stereochemical composition was determined by means of HPLC and circular dichroism analysis. Finally, the activity of these JA-derivates was analyzed in planta. JA-Tyr and JA-Sei trigger JA-regulated plant responses, such as protein degradation and growth inhibition. These effects require the conversion of JA into JA-Ile and its recognition by the plant JA-Ile perception complex COI1-JAZ. Overall, these data suggest a mode-of-action of JA-Tyr and JA-Sei as inactive pool of JA that can be transformed into the bioactive JA-Ile to induce the canonical JA-Ile-pathway. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transition metal dissolution, ion migration, electrocatalytic reduction and capacity loss in Lithium-ion full cells

DOE PAGES

Gilbert, James A.; Shkrob, Ilya A.; Abraham, Daniel P.

2017-01-05

Continuous operation of full cells with layered transition metal (TM) oxide positive electrodes (NCM523) leads to dissolution of TM ions and their migration and incorporation into the solid electrolyte interphase (SEI) of the graphite-based negative electrode. These processes correlate with cell capacity fade and accelerate markedly as the upper cutoff voltage (UCV) exceeds 4.30 V. At voltages ≥ 4.4 V there is enhanced fracture of the oxide during cycling that creates new surfaces and causes increased solvent oxidation and TM dissolution. Despite this deterioration, cell capacity fade still mainly results from lithium loss in the negative electrode SEI. Among TMs,more » Mn content in the SEI shows a better correlation with cell capacity loss than Co and Ni contents. As Mn ions become incorporated into the SEI, the kinetics of lithium trapping change from power to linear at the higher UCVs, indicating a large effect of these ions on SEI growth and implicating (electro)catalytic reactions. Lastly, we estimate that each Mn II ion deposited in the SEI causes trapping of ~10 2 additional Li + ions thereby hastening the depletion of cyclable lithium ions. Using these results, we sketch a mechanism for cell capacity fade, emphasizing the conceptual picture over the chemical detail.« less

Building Organic/Inorganic Hybrid Interphases for Fast Interfacial Transport in Rechargeable Metal Batteries.

PubMed

Zhao, Qing; Tu, Zhengyuan; Wei, Shuya; Zhang, Kaihang; Choudhury, Snehashis; Liu, Xiaotun; Archer, Lynden A

2018-01-22

We report a facile in situ synthesis that utilizes readily accessible SiCl 4 cross-linking chemistry to create durable hybrid solid-electrolyte interphases (SEIs) on metal anodes. Such hybrid SEIs composed of Si-interlinked OOCOR molecules that host LiCl salt exhibit fast charge-transfer kinetics and as much as five-times higher exchange current densities, in comparison to their spontaneously formed analogues. Electrochemical analysis and direct optical visualization of Li and Na deposition in symmetric Li/Li and Na/Na cells show that the hybrid SEI provides excellent morphological control at high current densities (3-5 mA cm -2 ) for Li and even for notoriously unstable Na metal anodes. The fast interfacial transport attributes of the SEI are also found to be beneficial for Li-S cells and stable electrochemical cycling was achieved in galvanostatic studies at rates as high as 2 C. Our work therefore provides a promising approach towards rational design of multifunctional, elastic SEIs that overcome the most serious limitations of spontaneously formed interphases on high-capacity metal anodes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Capacity Fade and Its Mitigation in Li-Ion Cells with Silicon-Graphite Electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bareno, Javier; Shkrob, Ilya A.; Gilbert, James A.

Silicon-graphite (Si-Gr) electrodes typically contain lithiated carboxylates as polymer binders that are introduced through aqueous processing. Li-ion cells with such electrodes show significantly faster capacity fade than cells with graphite (Gr) electrodes. Here we examine the causes for capacity loss in Si-Gr cells containing LiPF 6-based electrolytes. The presence of SiO xF y in the Si-Gr electrode, fluorophosphate species in the electrolyte, and silica on the positive electrode indicates the crucial role of the hydrolytic cycle. In particular, HF acid that is generated through LiPF 6 hydrolysis corrodes Si particles. As it reacts, the released water re-enters the cycle. Wemore » trace the moisture initiating this detrimental cycle to the hydration water in the lithiated binders that cannot be fully removed by thermal treatment. The rate of HF corrosion can be reduced through the use of electrolyte additives. For the fluoroethylene carbonate (FEC) additive, the improved performance arises from changes to the solid electrolyte interphase (SEI) that serves as a barrier against HF attack. Here, we propose that the greater extent of polymer cross-linking, that gives FEC-derived SEI elastomer properties, slows down HF percolation through this SEI membrane and inhibits the formation of deep cracks through which HF can access and degrade the Si surface.« less

Capacity Fade and Its Mitigation in Li-Ion Cells with Silicon-Graphite Electrodes

DOE PAGES

Bareno, Javier; Shkrob, Ilya A.; Gilbert, James A.; ...

2017-09-06

Silicon-graphite (Si-Gr) electrodes typically contain lithiated carboxylates as polymer binders that are introduced through aqueous processing. Li-ion cells with such electrodes show significantly faster capacity fade than cells with graphite (Gr) electrodes. Here we examine the causes for capacity loss in Si-Gr cells containing LiPF 6-based electrolytes. The presence of SiO xF y in the Si-Gr electrode, fluorophosphate species in the electrolyte, and silica on the positive electrode indicates the crucial role of the hydrolytic cycle. In particular, HF acid that is generated through LiPF 6 hydrolysis corrodes Si particles. As it reacts, the released water re-enters the cycle. Wemore » trace the moisture initiating this detrimental cycle to the hydration water in the lithiated binders that cannot be fully removed by thermal treatment. The rate of HF corrosion can be reduced through the use of electrolyte additives. For the fluoroethylene carbonate (FEC) additive, the improved performance arises from changes to the solid electrolyte interphase (SEI) that serves as a barrier against HF attack. Here, we propose that the greater extent of polymer cross-linking, that gives FEC-derived SEI elastomer properties, slows down HF percolation through this SEI membrane and inhibits the formation of deep cracks through which HF can access and degrade the Si surface.« less

Ionic Liquid-Enhanced Solid State Electrolyte Interface (SEI) for Lithium Sulfur Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Jianming; Gu, Meng; Chen, Honghao

2013-05-16

Li-S battery is a complicated system with many challenges existing before its final market penetration. While most of the reported work for Li-S batteries is focused on the cathode design, we demonstrate in this work that the anode consumption accelerated by corrosive polysulfide solution also critically determines the Li-S cell performance. To validate this hypothesis, ionic liquid (IL) N-methyl-N-butylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Py14TFSI) has been employed to modify the properties of SEI layer formed on Li metal surface in Li-S batteries. It is found that the IL-enhanced passivation film on the lithium anode surface exhibits much different morphology and chemical compositions, effectivelymore » protecting lithium metal from continuous attack by soluble polysulfides. Therefore, both cell impedance and the irreversible consumption of polysulfides on lithium metal are reduced. As a result, the Coulombic efficiency and the cycling stability of Li-S batteries have been greatly improved. After 120 cycles, Li-S battery cycled in the electrolyte containing IL demonstrates a high capacity retention of 94.3% at 0.1 C rate. These results unveil another important failure mechanism for Li-S batteries and shin the light on the new approaches to improve Li-S battery performances.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehdi, Beata L.; Qian, Jiangfeng; Nasybulin, Eduard

Lithium (Li)-ion batteries are currently used for a wide variety of portable electronic devices, electric vehicles and renewable energy applications. In addition, extensive worldwide research efforts are now being devoted to more advanced “beyond Li-ion” battery chemistries - such as lithium-sulfur (Li-S) and lithium-air (Li-O2) - in which the carbon anode is replaced with Li metal. However, the practical application of Li metal anode systems has been highly problematic. The main challenges involve controlling the formation of a solid-electrolyte interphase (SEI) layer and the suppression of Li dendrite growth during the charge/discharge process (achieving “dendrite-free” cycling). The SEI layer formationmore » continuously consumes the electrolyte components creating highly resistive layer, which leads to the rapid decrease of cycling performance and degradation of the Li anode. The growth of Li metal dendrites at the anode contributes to rapid capacity fading (the presence of “dead Li” created during the discharge leads to an increased overpotential) and, in the case of continuous growth, leads to internal short circuits and extreme safety issues. Here we demonstrate the application of an operando electrochemical scanning transmission electron microscopy (ec-(S)TEM) cell to study the SEI layer formation and the initial stages of Li dendrite growth - the goal is to develop a mechanism for mitigating the degradation processes and increasing safety. Bright field (BF) STEM images in Figure 1 A-C show Li metal deposition and dissolution processes at the interface between the Pt working electrode and the lithium hexafluorophosphate (LiPF6) in propylene carbonate (PC) electrolyte during three charge/discharge cycles. A contrast reversal caused by Li metal being lighter/less dense than surrounding electrolyte (Li appears brighter than the background in BF STEM images) allows Li to be uniquely identified from the other components in the system - the only solid material that is less dense than the electrolyte is Li metal. Using these images, we can precisely quantify the total volume of Li deposition, the thickness of the SEI layer (observed as a ring of positive contrast around the electrode) and alloy formation due to Li+ ion insertion during each cycle. Furthermore, at the end of each discharge cycle we can quantify the presence of “dead Li” detached from the Pt electrode, thereby demonstrating the degree of irreversibility (and degradation of Pt electrode) associated with insertion/removal of Li+during this process with direct correlation to electrochemical performance. Such analyses provide significant insights into Li metal dendrite growth, which is critical to understand the complex interfacial reactions needed to be controlled for future Li-based and next generation energy storage systems.« less

Formation and Inhibition of Metallic Lithium Microstructures in Lithium Batteries Driven by Chemical Crossover

DOE PAGES

Li, Wangda; Kim, Un-Hyuck; Dolocan, Andrei; ...

2017-05-14

The formation of metallic lithium microstructures in the form of dendrites or mosses at the surface of anode electrodes (e.g., lithium metal, graphite, and silicon) leads to rapid capacity fade and poses grave safety risks in rechargeable lithium batteries. In this work, we present here a direct, relative quantitative analysis of lithium deposition on graphite anodes in pouch cells under normal operating conditions, paired with a model cathode material, the layered nickel-rich oxide LiNi 0.61Co 0.12Mn 0.27O 2, over the course of 3000 charge-discharge cycles. Secondary-ion mass spectrometry chemically dissects the solid-electrolyte interphase (SEI) on extensively cycled graphite with virtuallymore » atomic depth resolution and reveals substantial growth of Li-metal deposits. With the absence of apparent kinetic (e.g., fast charging) or stoichiometric restraints (e.g., overcharge) during cycling, we show lithium deposition on graphite is triggered by certain transition-metal ions (manganese in particular) dissolved from the cathode in a disrupted SEI. This insidious effect is found to initiate at a very early stage of cell operation (<200 cycles) and can be effectively inhibited by substituting a small amount of aluminum (~1 mol %) in the cathode, resulting in much reduced transition-metal dissolution and drastically improved cyclability. In conclusion, our results may also be applicable to studying the unstable electrodeposition of lithium on other substrates, including Li metal.« less

Formation and Inhibition of Metallic Lithium Microstructures in Lithium Batteries Driven by Chemical Crossover

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Wangda; Kim, Un-Hyuck; Dolocan, Andrei

The formation of metallic lithium microstructures in the form of dendrites or mosses at the surface of anode electrodes (e.g., lithium metal, graphite, and silicon) leads to rapid capacity fade and poses grave safety risks in rechargeable lithium batteries. In this work, we present here a direct, relative quantitative analysis of lithium deposition on graphite anodes in pouch cells under normal operating conditions, paired with a model cathode material, the layered nickel-rich oxide LiNi 0.61Co 0.12Mn 0.27O 2, over the course of 3000 charge-discharge cycles. Secondary-ion mass spectrometry chemically dissects the solid-electrolyte interphase (SEI) on extensively cycled graphite with virtuallymore » atomic depth resolution and reveals substantial growth of Li-metal deposits. With the absence of apparent kinetic (e.g., fast charging) or stoichiometric restraints (e.g., overcharge) during cycling, we show lithium deposition on graphite is triggered by certain transition-metal ions (manganese in particular) dissolved from the cathode in a disrupted SEI. This insidious effect is found to initiate at a very early stage of cell operation (<200 cycles) and can be effectively inhibited by substituting a small amount of aluminum (~1 mol %) in the cathode, resulting in much reduced transition-metal dissolution and drastically improved cyclability. In conclusion, our results may also be applicable to studying the unstable electrodeposition of lithium on other substrates, including Li metal.« less

Connecting the irreversible capacity loss in Li-ion batteries with the electronic insulating properties of solid electrolyte interphase (SEI) components.

DOE PAGES

Leung, Kevin; Lin, Yu -Xiao; Liu, Zhe; ...

2016-01-01

The formation and continuous growth of a solid electrolyte interphase (SEI) layer are responsible for the irreversible capacity loss of batteries in the initial and subsequent cycles, respectively. In this article, the electron tunneling barriers from Li metal through three insulating SEI components, namely Li 2CO 3, LiF and Li 3PO 4, are computed by density function theory (DFT) approaches. Based on electron tunneling theory, it is estimated that sufficient to block electron tunneling. It is also found that the band gap decreases under tension while the work function remains the same, and thus the tunneling barrier decreases under tensionmore » and increases under compression. A new parameter, η, characterizing the average distances between anions, is proposed to unify the variation of band gap with strain under different loading conditions into a single linear function of η. An analytical model based on the tunneling results is developed to connect the irreversible capacity loss, due to the Li ions consumed in forming these SEI component layers on the surface of negative electrodes. As a result, the agreement between the model predictions and experimental results suggests that only the initial irreversible capacity loss is due to the self-limiting electron tunneling property of the SEI.« less

Quantitative investigation of the gassing behavior in cylindrical Li4Ti5O12 batteries

NASA Astrophysics Data System (ADS)

Wang, Qian; Zhang, Jian; Liu, Wei; Xie, Xiaohua; Xia, Baojia

2017-03-01

The Li4Ti5O12 gassing behavior is a critical limitation for applications in lithium-ion batteries. The impact of electrode/electrolyte interface, as well as the underlying mechanisms involved during the gassing process, are still debated. Herein, a quantitative evolution of the internal pressure in 18650-type cylindrical Li4Ti5O12 batteries is investigated using a self-designed pressure testing device. The results indicate that the internal pressure significantly increases during the formation cycle and continues growing during the following cycles. After several charge and discharge cycles, the pressure finally reaches constant. Simultaneously, the formation of the solid electrolyte interphase (SEI) film is also investigated. The results suggest that the initial formed SEI film has a thickness of 24 nm, and is observed to shrink during the following cycles. Furthermore, no apparent increase in thickness accompanying the pressure rising is noticed. These comparative investigations reveal a possible mechanism of the gassing behavior. We suggest that the gassing behavior is associated with side reactions which are determined by the potential of the Li4Ti5O12 electrode, where the active sites of the electrode/electrolyte interface manage the extent of the reaction.

Fundamental Investigation of Silicon Anode in Lithium-Ion Cells

NASA Technical Reports Server (NTRS)

Wu, James J.; Bennett, William R.

2012-01-01

Silicon is a promising and attractive anode material to replace graphite for high capacity lithium ion cells since its theoretical capacity is 10 times of graphite and it is an abundant element on Earth. However, there are challenges associated with using silicon as Li-ion anode due to the significant first cycle irreversible capacity loss and subsequent rapid capacity fade during cycling. Understanding solid electrolyte interphase (SEI) formation along with the lithium ion insertion/de-insertion kinetics in silicon anodes will provide greater insight into overcoming these issues, thereby lead to better cycle performance. In this paper, cyclic voltammetry and electrochemical impedance spectroscopy are used to build a fundamental understanding of silicon anodes. The results show that it is difficult to form the SEI film on the surface of a Si anode during the first cycle; the lithium ion insertion and de-insertion kinetics for Si are sluggish, and the cell internal resistance changes with the state of lithiation after electrochemical cycling. These results are compared with those for extensively studied graphite anodes. The understanding gained from this study will help to design better Si anodes, and the combination of cyclic voltammetry with impedance spectroscopy provides a useful tool to evaluate the effectiveness of the design modifications on the Si anode performance.

Enhanced performance of graphite anode materials by AlF3 coating for lithium-ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, Fei; Xu, Wu; Choi, Daiwon

2012-04-27

In order to form the stable surface film and to further enhance the long-term cycling stability of the graphite anodes of lithium-ion batteries, the surface of graphite powders has been modified by AlF3 coating through chemical precipitation method. The AlF3-coated graphite shows no evident changes in the bulk structure and a thin AlF3-coating layer of about 2 nm thick is found to uniformly cover the graphite particles with 2 wt% AlF3 content. However, it delivers a higher initial discharge capacity and largely improved rate performances compared to the pristine graphite. Remarkably, AlF3 coated graphite demonstrated a much better cycle life.more » After 300 cycles, AlF3 coated graphite and uncoated graphite show capacity retention of 92% and 81%, respectively. XPS measurement shows that a more conductive solid electrode interface (SEI) layer was formed on AlF3 coated graphite as compared to uncoated graphite. SEM monograph also reveals that the AlF3-coated graphite particles have a much more stable surface morphology after long-term cycling. Therefore, the improved electrochemical performance of AlF3 coated graphite can be attributed to a more stable and conductive SEI formed on coated graphite anode during cycling process.« less

Exploring Lithium Deficiency in Layered Oxide Cathode for Li-Ion Battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Sung-Jin; Uddin, Md-Jamal; Alaboina, Pankaj K.

Abstract or short description: The ever-growing demand for high capacity cathode materials is on the rise since the futuristic applications are knocking on the door. Conventional approach to developing such cathode relies on the lithium-excess materials to operate the cathode at high voltage and extract more lithium-ion. Yet, they fail to satiate the needs because of their unresolved issues upon cycling such as, for lithium manganese-rich layered oxides – their voltage fading, and for as nickel-based layered oxides – the structural transition. Here, in contrast, lithium-deficient ratio is demonstrated as a new approach to attain high capacity at high voltagemore » for layered oxide cathodes. Rapid and cost effective lithiation of a porous hydroxide precursor with lithium deficient ratio acted as a driving force to partially convert the layered material to spinel phase yielding in a multiphase structure (MPS) cathode material. Upon cycling, MPS revealed structural stability at high voltage and high temperature and resulted in fast lithium-ion diffusion by providing a distinctive SEI chemistry – MPS displayed minimum lithium loss in SEI and formed a thinner SEI. MPS thus offer high energy and high power applications and provides a new perspective compared to the conventional layered cathode materials denying the focus for lithium excess material.« less

Homogeneous lithium electrodeposition with pyrrolidinium-based ionic liquid electrolytes.

PubMed

Grande, Lorenzo; von Zamory, Jan; Koch, Stephan L; Kalhoff, Julian; Paillard, Elie; Passerini, Stefano

2015-03-18

In this study, we report on the electroplating and stripping of lithium in two ionic liquid (IL) based electrolytes, namely N-butyl-N-methylpyrrolidinium bis(fluorosulfonyl) imide (Pyr14FSI) and N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI), and mixtures thereof, both on nickel and lithium electrodes. An improved method to evaluate the Li cycling efficiency confirmed that homogeneous electroplating (and stripping) of Li is possible with TFSI-based ILs. Moreover, the presence of native surface features on lithium, directly observable via scanning electron microscope imaging, was used to demonstrate the enhanced electrolyte interphase (SEI)-forming ability, that is, fast cathodic reactivity of this class of electrolytes and the suppressed dendrite growth. Finally, the induced inhomogeneous deposition enabled us to witness the SEI cracking and revealed previously unreported bundled Li fibers below the pre-existing SEI and nonrod-shaped protuberances resulting from Li extrusion.

Tuning the Solid Electrolyte Interphase for Selective Li- and Na-Ion Storage in Hard Carbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soto, Fernando A.; Yan, Pengfei; Engelhard, Mark H.

Solid-electrolyte interphase (SEI) films with controllable properties are highly desirable for improving battery performance. In this paper, a combined experimental and theoretical approach is used to study SEI films formed on hard carbon in Li- and Na-ion batteries. It is shown that a stable SEI layer can be designed by precycling an electrode in a desired Li- or Na-based electrolyte, and that ionic transport can be kinetically controlled. Selective Li- and Na-based SEI membranes are produced using Li- or Na-based electrolytes, respectively. The Na-based SEI allows easy transport of Li ions, while the Li-based SEI shuts off Na-ion transport. Na-ionmore » storage can be manipulated by tuning the SEI layer with film-forming electrolyte additives, or by preforming an SEI layer on the electrode surface. The Na specific capacity can be controlled to < 25 mAh g(-1); approximate to 1/10 of the normal capacity (250 mAh g(-1)). Unusual selective/ preferential transport of Li ions is demonstrated by preforming an SEI layer on the electrode surface and corroborated with a mixed electrolyte. This work may provide new guidance for preparing good ion-selective conductors using electrochemical approaches.« less

Dissecting seipin function: the localized accumulation of phosphatidic acid at ER/LD junctions in the absence of seipin is suppressed by Sei1p(ΔNterm) only in combination with Ldb16p.

PubMed

Han, Sungwon; Binns, Derk D; Chang, Yu-Fang; Goodman, Joel M

2015-12-04

Seipin is required for the correct assembly of cytoplasmic lipid droplets. In the absence of the yeast seipin homolog Sei1p (formerly Fld1p), droplets are slow to bud from the endoplasmic reticulum, lack the normal component of proteins on their surface, are highly heterogeneous in size and shape, often bud into the nucleus, and promote local proliferation of the endoplasmic reticulum in which they become tangled. But the mechanism by which seipin catalyzes lipid droplet formation is still uncertain. Seipin prevents a localized accumulation of phosphatidic acid (PA puncta) at ER-droplet junctions. PA puncta were detected with three different probes: Opi1p, Spo20p(51-91) and Pah1p. A system of droplet induction was used to show that PA puncta were not present until droplets were formed; the puncta appeared regardless of whether droplets consisted of triacylglycerol or steryl ester. Deletion strains were used to demonstrate that a single phosphatidic acid-producing enzyme is not responsible for the generation of the puncta, and the puncta remain resistant to overexpression of enzymes that metabolize phosphatidic acid, suggesting that this lipid is trapped in a latent compartment. Suppression of PA puncta requires the first 14 amino acids of Sei1p (Nterm), a domain that is also important for initiation of droplet assembly. Consistent with recent evidence that Ldb16p and Sei1p form a functional unit, the PA puncta phenotype in the ldb16Δ sei1Δ strain was rescued by human seipin. Moreover, PA puncta in the sei1Δ strain expressing Sei1p(ΔNterm) was suppressed by overexpression of Ldb16p, suggesting a functional interaction of Nterm with this protein. Overexpression of both Sei1p and Ldb16p, but not Sei1p alone, is sufficient to cause a large increase in droplet number. However, Ldb16p alone increases triacylglycerol accumulation in the ldb16Δ sei1Δ background. We hypothesize that seipin prevents formation of membranes with extreme curvature at endoplasmic reticulum/droplet junctions that would attract phosphatidic acid. While Ldb16p alone can affect triacylglycerol accumulation, proper droplet formation requires the collaboration of Sei1p and Ldb16.

Computational Exploration of the Li-Electrode|Electrolyte Interface in the Presence of a Nanometer Thick Solid-Electrolyte Interphase Layer [Computational exploration of the Li-electrode|electrolyte interface complicated by a nanometer thin solid-electrolyte interphase (SEI) layer

DOE PAGES

Li, Yunsong; Leung, Kevin; Qi, Yue

2016-09-30

A nanometer thick passivation layer will spontaneously form on Li-metal in battery applications due to electrolyte reduction reactions. This passivation layer in rechargeable batteries must have “selective” transport properties: blocking electrons from attacking the electrolytes, while allowing Li + ion to pass through so the electrochemical reactions can continue. The classical description of the electrochemical reaction, Li + + e → Li 0, occurring at the Li-metal|electrolyte interface is now complicated by the passivation layer and will reply on the coupling of electronic and ionic degrees of freedom in the layer. We consider the passivation layer, called “solid electrolyte interphasemore » (SEI)”, as “the most important but the least understood in rechargeable Li-ion batteries,” partly due to the lack of understanding of its structure–property relationship. In predictive modeling, starting from the ab initio level, we find that it is an important tool to understand the nanoscale processes and materials properties governing the interfacial charge transfer reaction at the Li-metal|SEI|electrolyte interface. Here, we demonstrate pristine Li-metal surfaces indeed dissolve in organic carbonate electrolytes without the SEI layer. Based on joint modeling and experimental results, we point out that the well-known two-layer structure of SEI also exhibits two different Li + ion transport mechanisms. The SEI has a porous (organic) outer layer permeable to both Li + and anions (dissolved in electrolyte), and a dense (inorganic) inner layer facilitate only Li + transport. This two-layer/two-mechanism diffusion model suggests only the dense inorganic layer is effective at protecting Li-metal in electrolytes. This model suggests a strategy to deconvolute the structure–property relationships of the SEI by analyzing an idealized SEI composed of major components, such as Li 2CO 3, LiF, Li 2O, and their mixtures. After sorting out the Li+ ion diffusion carriers and their diffusion pathways, we design methods to accelerate the Li + ion conductivity by doping and by using heterogonous structure designs. We will predict the electron tunneling barriers and connect them with measurable first cycle irreversible capacity loss. We note that the SEI not only affects Li + and e – transport, but it can also impose a potential drop near the Li-metal|SEI interface. Our challenge is to fully describe the electrochemical reactions at the Li -metal|SEI|electrolyte interface. This will be the subject of ongoing efforts.« less

Computational Exploration of the Li-Electrode|Electrolyte Interface in the Presence of a Nanometer Thick Solid-Electrolyte Interphase Layer [Computational exploration of the Li-electrode|electrolyte interface complicated by a nanometer thin solid-electrolyte interphase (SEI) layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yunsong; Leung, Kevin; Qi, Yue

A nanometer thick passivation layer will spontaneously form on Li-metal in battery applications due to electrolyte reduction reactions. This passivation layer in rechargeable batteries must have “selective” transport properties: blocking electrons from attacking the electrolytes, while allowing Li + ion to pass through so the electrochemical reactions can continue. The classical description of the electrochemical reaction, Li + + e → Li 0, occurring at the Li-metal|electrolyte interface is now complicated by the passivation layer and will reply on the coupling of electronic and ionic degrees of freedom in the layer. We consider the passivation layer, called “solid electrolyte interphasemore » (SEI)”, as “the most important but the least understood in rechargeable Li-ion batteries,” partly due to the lack of understanding of its structure–property relationship. In predictive modeling, starting from the ab initio level, we find that it is an important tool to understand the nanoscale processes and materials properties governing the interfacial charge transfer reaction at the Li-metal|SEI|electrolyte interface. Here, we demonstrate pristine Li-metal surfaces indeed dissolve in organic carbonate electrolytes without the SEI layer. Based on joint modeling and experimental results, we point out that the well-known two-layer structure of SEI also exhibits two different Li + ion transport mechanisms. The SEI has a porous (organic) outer layer permeable to both Li + and anions (dissolved in electrolyte), and a dense (inorganic) inner layer facilitate only Li + transport. This two-layer/two-mechanism diffusion model suggests only the dense inorganic layer is effective at protecting Li-metal in electrolytes. This model suggests a strategy to deconvolute the structure–property relationships of the SEI by analyzing an idealized SEI composed of major components, such as Li 2CO 3, LiF, Li 2O, and their mixtures. After sorting out the Li+ ion diffusion carriers and their diffusion pathways, we design methods to accelerate the Li + ion conductivity by doping and by using heterogonous structure designs. We will predict the electron tunneling barriers and connect them with measurable first cycle irreversible capacity loss. We note that the SEI not only affects Li + and e – transport, but it can also impose a potential drop near the Li-metal|SEI interface. Our challenge is to fully describe the electrochemical reactions at the Li -metal|SEI|electrolyte interface. This will be the subject of ongoing efforts.« less

Organizational Considerations for Implementing Systems Engineering and Integration in the Ares Projects Office

NASA Technical Reports Server (NTRS)

Thomas, LeAnn; Doreswamy, Rajiv N.

2008-01-01

Systems Engineering and Integration (SE&I) is a critical discipline in developing new space systems. In 2005, NASA performed an internal study of 24 agency and Department of Defense (DoD) programs to evaluate methods of integrating SE&I practices and determine their effectiveness. The goal of the study was to determine the best SE&I implementation strategy for the Ares Projects Office. The study identified six SE&I organizational structures: 1. Lead systems integrator (LSI) with SE&I responsibility and government technical insight. 2a. Integration contractor with government SE&I responsibility (government insight). 2b. Integration contractor with government SE&I responsibility (government oversight). 3a. Prime contractor with SE&I responsibility (government insight). 3b. Prime contractor with SE&I responsibility (government oversight). 3c. Prime contractor with SE&I responsibility (government/industry partnership). 4a.Prime contractor with government SE&I responsibility (government insight). 4b. Prime contractor with government SE&I responsibility (government oversight). 4d.Prime contractors with total system performance responsibility (TSPR). 5. Prime contractor with government SE&I responsibility and integration products through a Federally Funded Research and Development Center (FFRDC). 6. Government/FFRDC in-house development with SE&I responsibility and function. The organizational structure used most often was number 4, using a prime contractor with government SE&I responsibility and government technical insight. However, data analyses did not establish a positive relationship between program development costs and specific SE&I organizational types, nor did it positively determine the relationship between successful programs or projects and their SE&I structure. The SE&I study reached the following conclusions: (1) Large, long-duration, technically complex programs or projects reach their technical goals, but rarely meet schedule or cost goals. NASA's recent successes have been smaller, short-duration development projects using heritage hardware/software, focused technology development, technical oversight and stable external factors. (2) Programs and projects have failed or been terminated due to lack of technical insight, relaxing of SE&I processes, and unstable external factors. (3) The study did not find a single, clear optimum SE&I organization type to fit all projects. However, while any organizational structure can be made to work, the fewer complexities in the program, the better the likelihood of success. (4) The most common successful SE&I organization structure type in the study was type 4b, where the government maintained integration responsibility, with the prime contractor providing SE&I products and the government providing technical oversight. This study was instrumental in helping the APO select organization structure 4, following the same SE&I and oversight process used during humanlund7s last voyages to the Moon.

Alkali Metal Rankine Cycle Boiler Technology Challenges and Some Potential Solutions for Space Nuclear Power and Propulsion Applications

NASA Technical Reports Server (NTRS)

Stone, James R.

1994-01-01

Alkali metal boilers are of interest for application to future space Rankine cycle power conversion systems. Significant progress on such boilers was accomplished in the 1960's and early 1970's, but development was not continued to operational systems since NASA's plans for future space missions were drastically curtailed in the early 1970's. In particular, piloted Mars missions were indefinitely deferred. With the announcement of the Space Exploration Initiative (SEI) in July 1989 by President Bush, interest was rekindled in challenging space missions and, consequently in space nuclear power and propulsion. Nuclear electric propulsion (NEP) and nuclear thermal propulsion (NTP) were proposed for interplanetary space vehicles, particularly for Mars missions. The potassium Rankine power conversion cycle became of interest to provide electric power for NEP vehicles and for 'dual-mode' NTP vehicles, where the same reactor could be used directly for propulsion and (with an additional coolant loop) for power. Although the boiler is not a major contributor to system mass, it is of critical importance because of its interaction with the rest of the power conversion system; it can cause problems for other components such as excess liquid droplets entering the turbine, thereby reducing its life, or more critically, it can drive instabilities-some severe enough to cause system failure. Funding for the SEI and its associated technology program from 1990 to 1993 was not sufficient to support significant new work on Rankine cycle boilers for space applications. In Fiscal Year 1994, funding for these challenging missions and technologies has again been curtailed, and planning for the future is very uncertain. The purpose of this paper is to review the technologies developed in the 1960's and 1970's in the light of the recent SEI applications. In this way, future Rankine cycle boiler programs may be conducted most efficiently. This report is aimed at evaluating alkali metal boiler technology for space Rankine cycle systems. Research is summarized on the problems of flow stability, liquid carryover, pressure drop and heat transfer, and on potential solutions developed, primarily those developed by the NASA Lewis Research Center in the 1960's and early 1970's.

Effects of High and Low Salt Concentration in Electrolytes at Lithium–Metal Anode Surfaces

DOE PAGES

Camacho-Forero, Luis E.; Smith, Taylor W.; Balbuena, Perla B.

2016-12-16

The use of high concentration salts in electrolyte solutions of lithium-sulfur (Li-S) batteries has been shown beneficial for mitigating some effects such as polysulfide shuttle and dendrite growth at the Li metal anode. Such complex solutions have structural, dynamical, and reactivity associated issues that need to be analyzed for a better understanding of the reasons behind such beneficial effects. A passivation interfacial layer known as solid-electrolyte interphase (SEI) is generated during battery cycling as a result of electron transfer from the metal anode causing electrolyte decomposition. Here in this work, we investigate using density functional theory and ab initio molecularmore » dynamics simulations the salt decomposition, solvation effects, interactions among intermediate products and other species, and potential components of the SEI layer as a function of chemical nature and concentration of the salt, for lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluorosulfonyl)imide (LiFSI) at 1M and 4M concentrations in dimethoxyethane. It is found that LiTFSI undergoes a less complete reduction and facilitates charge transfer from the anode, whereas LiFSI shows a more complete decomposition forming LiF as one of the main SEI products. In addition, the specific decomposition mechanisms of each salt clearly point to the initial SEI components and the potential main products derived from them. Finally, very complex networks are found among the salt and solvent molecules in their attempt to maximize Li ion solvation that is quantified through the determination of coordination numbers.« less

Fluorinated End-Groups in Electrolytes Induce Ordered Electrolyte/Anode Interface Even at Open-Circuit Potential as Revealed by Sum Frequency Generation Vibrational Spectroscopy

DOE PAGES

Horowitz, Yonatan; Han, Hui-Ling; Ralston, Walter T.; ...

2017-05-12

Fluorine-based additives have a tremendously beneficial effect on the performance of lithium-ion batteries, yet the origin of this phenomenon is unclear. This study shows that the formation of a solid-electrolyte interphase (SEI) on the anode surface in the first five charge/discharge cycles is affected by the stereochemistry of the electrolyte molecules on the anode surface starting at open-circuit potential (OCP). This study shows an anode-specific model system, the reduction of 1,2-diethoxy ethane with lithium bis(trifluoromethane)sulfonimide, as a salt on an amorphous silicon anode, and compares the electrochemical response and SEI formation to its fluorinated version, bis(2,2,2-trifluoroethoxy) ethane (BTFEOE), by summore » frequency generation (SFG) vibrational spectroscopy under reaction conditions. The SFG results suggest that the —CF 3 end-groups of the linear ether BTFEOE change their adsorption orientation on the a-Si surface at OCP, leading to a better protective layer. Finally, supporting evidence from ex situ scanning electron microscopy and X-ray photoelectron spectroscopy depth profiling measurements shows that the fluorinated ether, BTFEOE, yields a smooth SEI on the a-Si surface and enables lithium ions to intercalate deeper into the a-Si bulk.« less

Fluorinated End-Groups in Electrolytes Induce Ordered Electrolyte/Anode Interface Even at Open-Circuit Potential as Revealed by Sum Frequency Generation Vibrational Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horowitz, Yonatan; Han, Hui-Ling; Ralston, Walter T.

Fluorine-based additives have a tremendously beneficial effect on the performance of lithium-ion batteries, yet the origin of this phenomenon is unclear. This study shows that the formation of a solid-electrolyte interphase (SEI) on the anode surface in the first five charge/discharge cycles is affected by the stereochemistry of the electrolyte molecules on the anode surface starting at open-circuit potential (OCP). This study shows an anode-specific model system, the reduction of 1,2-diethoxy ethane with lithium bis(trifluoromethane)sulfonimide, as a salt on an amorphous silicon anode, and compares the electrochemical response and SEI formation to its fluorinated version, bis(2,2,2-trifluoroethoxy) ethane (BTFEOE), by summore » frequency generation (SFG) vibrational spectroscopy under reaction conditions. The SFG results suggest that the —CF 3 end-groups of the linear ether BTFEOE change their adsorption orientation on the a-Si surface at OCP, leading to a better protective layer. Finally, supporting evidence from ex situ scanning electron microscopy and X-ray photoelectron spectroscopy depth profiling measurements shows that the fluorinated ether, BTFEOE, yields a smooth SEI on the a-Si surface and enables lithium ions to intercalate deeper into the a-Si bulk.« less

Compact-Nanobox Engineering of Transition Metal Oxides with Enhanced Initial Coulombic Efficiency for Lithium-Ion Battery Anodes.

PubMed

Zhu, Yanfei; Hu, Aiping; Tang, Qunli; Zhang, Shiying; Deng, Weina; Li, Yanhua; Liu, Zheng; Fan, Binbin; Xiao, Kuikui; Liu, Jilei; Chen, Xiaohua

2018-03-14

A novel strategy is proposed to construct a compact-nanobox (CNB) structure composed of irregular nanograins (average diameter ≈ 10 nm), aiming to confine the electrode-electrolyte contact area and enhance initial Coulombic efficiency (ICE) of transition metal oxide (TMO) anodes. To demonstrate the validity of this attempt, CoO-CNB is taken as an example which is synthesized via a carbothermic reduction method. Benefiting from the compact configuration, electrolyte can only contact the outer surface of the nanobox, keeping the inner CoO nanograins untouched. Therefore, the solid electrolyte interphase (SEI) formation is reduced. Furthermore, the internal cavity leaves enough room for volume variation upon lithiation and delithiation, resulting in superior mechanical stability of the CNB structure and less generation of fresh SEI. Consequently, the SEI remains stable and spatially confined without degradation, and hence, the CoO-CNB electrode delivers an enhanced ICE of 82.2%, which is among the highest values reported for TMO-based anodes in lithium-ion batteries. In addition, the CoO-CNB electrode also demonstrates excellent cyclability with a reversible capacity of 811.6 mA h g -1 (90.4% capacity retention after 100 cycles). These findings open up a new way to design high-ICE electrodes and boost the practical application of TMO anodes.

Cu2+1O coated polycrystalline Si nanoparticles as anode for lithium-ion battery.

PubMed

Zhang, Junying; Zhang, Chunqian; Wu, Shouming; Liu, Zhi; Zheng, Jun; Zuo, Yuhua; Xue, Chunlai; Li, Chuanbo; Cheng, Buwen

2016-12-01

Cu2+1O coated Si nanoparticles were prepared by simple hydrolysis and were investigated as an anode material for lithium-ion battery. The coating of Cu2+1O on the surface of Si particles remarkably improves the cycle performance of the battery than that made by the pristine Si. The battery exhibits an initial reversible capacity of 3063 mAh/g and an initial coulombic efficiency (CE) of 82.9 %. With a current density of 300 mA/g, its reversible capacity can remains 1060 mAh/g after 350 cycles, corresponding to a CE ≥ 99.8 %. It is believed that the Cu2+1O coating enhances the electrical conductivity, and the elasticity of Cu2+1O further helps buffer the volume changes during lithiation/delithiation processes. Experiment results indicate that the electrode maintained a highly integrated structure after 100 cycles and it is in favour of the formation of stable solid electrolyte interface (SEI) on the Si surface to keep the extremely high CE during long charge and discharge cycles.

High performance sulfur graphite full cell for next generation sulfur Li-ion battery

NASA Astrophysics Data System (ADS)

Wu, Yunwen; Momma, Toshiyuki; Yokoshima, Tokihiko; Nara, Hiroki; Osaka, Tetsuya

2018-06-01

Sulfur (S) Li-ion battery which use the metallic Li free anode is deemed as a promising solution to conquer the hazards originating from Li metal. However, stable cycling performance and low production price of the S Li-ion battery still remain challenging. Here, we propose a S-LixC full cell system by paring a S cathode and a pre-lithiated graphite anode which is cheap and commercially available. It shows stable cycling performance with a capacity around 1300 mAh (g-S)-1 at 0.2 C-rate and 1000 mAh (g-S)-1 at 0.5 C-rate. In addition, 0.1% per cycle capacity fading rate with a capacity retention of 880 mAh (g-S)-1 after 400 cycles at 0.2 C-rate has been achieved. The pre-formed solid electrolyte interphase (SEI) layer on the pre-lithaited graphite anode largely contributes to the high capacity performance. Notably, a 10-times-enlarged scale of S-LixC laminate type full cell has been assembled with high capacity performance (around 1000 mAh (g-S)-1) even after high rate cycling.

Degradation diagnosis of lithium-ion batteries with a LiNi0.5Co0.2Mn0.3O2 and LiMn2O4 blended cathode using dV/dQ curve analysis

NASA Astrophysics Data System (ADS)

Ando, Keisuke; Matsuda, Tomoyuki; Imamura, Daichi

2018-06-01

Understanding the degradation factors (cathode and anode degradation and solid electrolyte interface (SEI) formation) of lithium-ion batteries (LIBs) with a blended cathode is necessary to improve their durability because battery drive vehicles often use LIBs with a blended cathode due to advantages of power and cost. We developed a dV/dQ curve analysis adapted for through a dQ/dV curve analysis to elucidate the relations between cycle test conditions and degradation factors. To compare said factors, cycle tests were conducted under different conditions: one charge/discharge rate (C/3), two state-of-charge (SoC) ranges (100%-0% and 100%-70%), and three temperatures (0 °C, 25 °C, and 45 °C). We confirmed that there are clear differences in the degree of contribution of each degradation factor depending on conditions. For instance, at 0 °C, although the capacity reduction rate was almost the same regardless of the SoC range, the degradation mechanisms were different, i.e., the cathode degradation and the SEI formation occurred at the same time, resulting in the reduced capacity for the 100%-0% SoC range, while capacity reduction was mainly due to SEI formation for the 100%-70% SoC range.

The effect of water-containing electrolyte on lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

Wu, Heng-Liang; Haasch, Richard T.; Perdue, Brian R.; Apblett, Christopher A.; Gewirth, Andrew A.

2017-11-01

Dissolved polysulfides, formed during Li-S battery operation, freely migrate and react with both the Li anode and the sulfur cathode. These soluble polysulfides shuttle between the anode and cathode - the so-called shuttle effect - resulting in an infinite recharge process and poor Columbic efficiency. In this study, water present as an additive in the Li-S battery electrolyte is found to reduce the shuttle effect in Li-S batteries. Batteries where water content was below 50 ppm exhibited a substantial shuttle effect and low charge capacity. Alternatively, addition of 250 ppm water led to stable charge/discharge behavior with high Coulombic efficiency. XPS results show that H2O addition results in the formation of solid electrolyte interphase (SEI) film with more LiOH on Li anode which protects the Li anode from the polysulfides. Batteries cycled without water result in a SEI film with more Li2CO3 likely formed by direct contact between the Li metal and the solvent. Intermediate quantities of H2O in the electrolyte result in high cycle efficiency for the first few cycles which then rapidly decays. This suggests that H2O is consumed during battery cycling, likely by interaction with freshly exposed Li metal formed during Li deposition.

Fast-pulverization enabled simultaneous enhancement on cycling stability and rate capability of C@NiFe2O4 hierarchical fibrous bundle

NASA Astrophysics Data System (ADS)

Chen, Zerui; Zhang, Yu; Wang, Xiaoling; Sun, Wenping; Dou, Shixue; Huang, Xin; Shi, Bi

2017-09-01

Electrochemical-grinding induced pulverization is the origin of capacity fading in NiFe2O4. Increasing current density normally accelerates the pulverization that deteriorates lithium storage properties of NiFe2O4. Here we show that the high current induced fast-pulverization can serve as an efficient activation strategy for quick and simultaneous enhancement on cycling stability and rate capability of NiFe2O4 nanoparticles (NPs) that are densely packed on the hierarchically structured carbon nanofiber strand. At a high current density, the pulverization of NiFe2O4 NPs can be accomplished in a few cycles exposing more active surface. During the fast-pulverization, the hierarchically structured carbon nanofiber strand maintains conductive contact for the densely packed NiFe2O4 NPs regardless of charge or discharge, which also effectively suppresses the repetitive breaks and growths of solid-electrolyte-interphase (SEI) via multiple-level structural adaption that favourites the quick formation of a thin and dense SEI, thus providing strong interparticle connectivity with enhancement on cycling stability and rate capability (e.g. doubled capacity). Our findings demonstrate the potential importance of high current induced fast-pulverization as an efficient activation strategy for achieving durable electrode materials suffering from electrochemical-grinding effects.

Electrolyte additive enabled fast charging and stable cycling lithium metal batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Jianming; Engelhard, Mark H.; Mei, Donghai

2017-03-01

Lithium (Li) metal battery is an attractive energy storage system owing to the ultrahigh specific capacity and the lowest redox potential of Li metal anode. However, safety concern associated with dendrite growth and limited cycle life especially at a high charge current density are two critical challenges hindering the practical applications of rechargeable Li metal batteries. Here, we report for the first time that an optimal amount (0.05 M) of LiPF6 as additive in the LiTFSI-LiBOB dual-salt/carbonate-based electrolyte can significantly enhance the charging capability and the long-term cycle life of Li metal batteries with a moderately high cathode loading ofmore » 1.75 mAh cm-2. Unprecedented stable-cycling (97.1% capacity retention after 500 cycles) along with very limited increase in electrode over-potential has been achieved at a high current density of 1.75 mA cm-2. This unparalleled fast charging and stable cycling performance is contributed from both the stabilized Al cathode current collector, and, more importantly, the robust and conductive SEI layer formed on Li metal anode in the presence of the LiPF6 additive.« less

The effect of gradient boracic polyanion-doping on structure, morphology, and cycling performance of Ni-rich LiNi0.8Co0.15Al0.05O2 cathode material

NASA Astrophysics Data System (ADS)

Chen, Tao; Li, Xiang; Wang, Hao; Yan, Xinxiu; Wang, Lei; Deng, Bangwei; Ge, Wujie; Qu, Meizhen

2018-01-01

A gradient boracic polyanion-doping method is applied to Ni-rich LiNi0.8Co0.15Al0.05O2 (NCA) cathode material in this study to suppress the capacity/potential fade during charge-discharge cycling. Scanning electron microscope (SEM) results show that all samples present spherical morphology and the secondary particle size increases with increasing boron content. X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) results demonstrate that boracic polyanions are successfully introduced into the bulk material and more enriched in the outer layer. XPS analysis further reveals that the valence state of Ni3+ is partly reduced to Ni2+ at the surface due to the incorporation of boracic polyanions. From the electrochemical measurements, B0.015-NCA electrode exhibits excellent cycling performance, even at high potential and elevated temperature. Moreover, the SEM images illustrate the presence of cracks and a thick SEI layer on pristine particles after 100 cycles at high temperature, while the B0.015-NCA particles show an intact structure and thin SEI layer. Electrochemical impedance spectroscopy confirms that the boracic polyanion doping could hinder the impedance increase during cycling at elevated temperature. These results clearly indicate that the gradient boracic polyanion-doping contributes to the remarkable enhancement of structure stability and cycling performance of NCA.

Interfacial reactions in lithium batteries

NASA Astrophysics Data System (ADS)

Chen, Zonghai; Amine, Rachid; Ma, Zi-Feng; Amine, Khalil

2017-08-01

The lithium-ion battery was first commercially introduced by Sony Corporation in 1991 using LiCoO2 as the cathode material and mesocarbon microbeads (MCMBs) as the anode material. After continuous research and development for 25 years, lithium-ion batteries have been the dominant energy storage device for modern portable electronics, as well as for emerging applications for electric vehicles and smart grids. It is clear that the success of lithium-ion technologies is rooted to the existence of a solid electrolyte interphase (SEI) that kinetically suppresses parasitic reactions between the lithiated graphitic anodes and the carbonate-based non-aqueous electrolytes. Recently, major attention has been paid to the importance of a similar passivation/protection layer on the surface of cathode materials, aiming for a rational design of high-energy-density lithium-ion batteries with extended cycle/calendar life. In this article, the physical model of the SEI, as well as recent research efforts to understand the nature and role of the SEI are summarized, and future perspectives on this important research field will also be presented.

Evaluation of the SEI using a multilayer spectroscopic ellipsometry model

DOE PAGES

Dufek, Eric J.

2014-08-28

A multilayer spectroscopic ellipsometry (SE) model has been developed to characterize SEI formation. The model, which consists of two Cauchy layers, is constructed with an inner layer meant to model primarily inorganic compounds adjacent to an electrode and an outer layer which mirrors polymeric, organic constituents on the exterior of the SEI. Comparison of 1:1 EC:EMC and 1:4 EC:EMC with 1.0 M LiPF₆ shows distinct differences in the two modeled layers. The data suggest that the thickness of both layers change over a wide potential range. These changes have been linked with other reports on the growth of the SEI.

Silicon algae with carbon topping as thin-film anodes for lithium-ion microbatteries by a two-step facile method

NASA Astrophysics Data System (ADS)

Biserni, E.; Xie, M.; Brescia, R.; Scarpellini, A.; Hashempour, M.; Movahed, P.; George, S. M.; Bestetti, M.; Li Bassi, A.; Bruno, P.

2015-01-01

Silicon-based electrodes for Li-ion batteries (LIB) attract much attention because of their high theoretical capacity. However, their large volume change during lithiation results in poor cycling due to mechanical cracking. Moreover, silicon can hardly form a stable solid electrolyte interphase (SEI) layer with common electrolytes. We present a safe, innovative strategy to prepare nanostructured silicon-carbon anodes in a two-step process. The nanoporosity of Si films accommodates the volume expansion while a disordered graphitic C layer on top promotes the formation of a stable SEI. This approach shows its promises: carbon-coated porous silicon anodes perform in a very stable way, reaching the areal capacity of ∼175 μAh cm-2, and showing no decay for at least 1000 cycles. With requiring only a two-step deposition process at moderate temperatures, this novel very simple cell concept introduces a promising way to possibly viable up-scaled production of next-generation nanostructured Si anodes for lithium-ion microbatteries.

Hollow carbon nanospheres/silicon/alumina core-shell film as an anode for lithium-ion batteries

PubMed Central

Li, Bing; Yao, Fei; Bae, Jung Jun; Chang, Jian; Zamfir, Mihai Robert; Le, Duc Toan; Pham, Duy Tho; Yue, Hongyan; Lee, Young Hee

2015-01-01

Hollow carbon nanospheres/silicon/alumina (CNS/Si/Al2O3) core-shell films obtained by the deposition of Si and Al2O3 on hollow CNS interconnected films are used as the anode materials for lithium-ion batteries. The hollow CNS film acts as a three dimensional conductive substrate and provides void space for silicon volume expansion during electrochemical cycling. The Al2O3 thin layer is beneficial to the reduction of solid-electrolyte interphase (SEI) formation. Moreover, as-designed structure holds the robust surface-to-surface contact between Si and CNSs, which facilitates the fast electron transport. As a consequence, the electrode exhibits high specific capacity and remarkable capacity retention simultaneously: 1560 mA h g−1 after 100 cycles at a current density of 1 A g−1 with the capacity retention of 85% and an average decay rate of 0.16% per cycle. The superior battery properties are further confirmed by cyclic voltammetry (CV) and impedance measurement. PMID:25564245

Facile synthesis of tin dioxide-based high performance anodes for lithium ion batteries assisted by graphene gel

NASA Astrophysics Data System (ADS)

Wan, Yuanxin; Sha, Ye; Luo, Shaochuan; Deng, Weijia; Wang, Xiaoliang; Xue, Gi; Zhou, Dongshan

2015-11-01

Tin dioxide (SnO2) is an attractive material for anodes in energy storage devices, because it has four times the theoretical capacity of the prevalent anode material (graphite). The main obstacle hampers SnO2 from practical application is the pulverization problem caused by drastic volume change (∼300%) during lithium-ion insertion or extraction, which would lead to the loss of electrical conductivity, unstable solid-electrolyte interphase (SEI) formation and consequently severe capacity fading in the cycling. Here, we anchored the SnO2 nanocrystals into three dimensional graphene gel network to tackle this problem. As a result of the three dimensional (3-D) architecture, the huge volume change during cycling was tolerated by the large free space in this 3-D construction, resulting in a high capacity of 1090 mAh g-1 even after 200 cycles. What's more, at a higher current density 5 A g-1, a reversible capacity of about 491 mAh g-1 was achieved with this electrode.

Interfacial Chemistry Regulation via a Skin-Grafting Strategy Enables High-Performance Lithium-Metal Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Yue; Zhao, Yuming; Li, Yuguang C.

The lithium (Li) metal anode suffers severe interfacial instability from its high reactivity toward liquid electrolytes, especially carbonate-based electrolytes, resulting in poor electrochemical performance of batteries that use 4 V high-capacity cathodes. In this paper, we report a new skin-grafting strategy that stabilizes the Li metal–liquid electrolyte interface by coating the Li metal surface with poly((N-2,2-dimethyl-1,3-dioxolane-4-methyl)-5-norbornene-exo-2,3-dicarboximide), a chemically and electrochemically active polymer layer. This layer, composed of cyclic ether groups with a stiff polycyclic main chain, serves as a grafted polymer skin on the Li metal anode not only to incorporate ether-based polymeric components into the solid-electrolyte interphase (SEI) butmore » also to accommodate Li deposition/dissolution under the skin in a dendrite/moss-free manner. Consequently, a Li-metal battery employing a Li metal anode with the grafted skin paired with LiNi 0.5Co 0.2Mn 0.3O 2 cathode has a 90.0% capacity retention after 400 charge/discharge cycles and a capacity of 1.2 mAh/cm 2 in a carbonate-based electrolyte. Finally, this proof-of-concept study provides a new direction for regulating the interfacial chemistry of Li metal anodes and for enabling high-performance Li-metal batteries.« less

Interfacial Chemistry Regulation via a Skin-Grafting Strategy Enables High-Performance Lithium-Metal Batteries

DOE PAGES

Gao, Yue; Zhao, Yuming; Li, Yuguang C.; ...

2017-10-06

The lithium (Li) metal anode suffers severe interfacial instability from its high reactivity toward liquid electrolytes, especially carbonate-based electrolytes, resulting in poor electrochemical performance of batteries that use 4 V high-capacity cathodes. In this paper, we report a new skin-grafting strategy that stabilizes the Li metal–liquid electrolyte interface by coating the Li metal surface with poly((N-2,2-dimethyl-1,3-dioxolane-4-methyl)-5-norbornene-exo-2,3-dicarboximide), a chemically and electrochemically active polymer layer. This layer, composed of cyclic ether groups with a stiff polycyclic main chain, serves as a grafted polymer skin on the Li metal anode not only to incorporate ether-based polymeric components into the solid-electrolyte interphase (SEI) butmore » also to accommodate Li deposition/dissolution under the skin in a dendrite/moss-free manner. Consequently, a Li-metal battery employing a Li metal anode with the grafted skin paired with LiNi 0.5Co 0.2Mn 0.3O 2 cathode has a 90.0% capacity retention after 400 charge/discharge cycles and a capacity of 1.2 mAh/cm 2 in a carbonate-based electrolyte. Finally, this proof-of-concept study provides a new direction for regulating the interfacial chemistry of Li metal anodes and for enabling high-performance Li-metal batteries.« less

Cycling behavior of NCM523/graphite lithium-ion cells in the 3–4.4 V range: Diagnostic studies of full cells and harvested electrodes

DOE PAGES

Gilbert, James A.; Bareño, Javier; Spila, Timothy; ...

2016-09-22

Energy density of full cells containing layered-oxide positive electrodes can be increased by raising the upper cutoff voltage above the current 4.2 V limit. In this article we examine aging behavior of cells, containing LiNi 0.5Co 0.2Mn 0.3O 2 (NCM523)-based positive and graphite-based negative electrodes, which underwent up to ~400 cycles in the 3-4.4 V range. Electrochemistry results from electrodes harvested from the cycled cells were obtained to identify causes of cell performance loss; these results were complemented with data from X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) measurements. Our experiments indicate that the full cell capacitymore » fade increases linearly with cycle number and results from irreversible lithium loss in the negative electrode solid electrolyte interphase (SEI) layer. The accompanying electrode potential shift reduces utilization of active material in both electrodes and causes the positive electrode to cycle at higher states-of-charge. Here, full cell impedance rise on aging arises primarily at the positive electrode and results mainly from changes at the electrode-electrolyte interface; the small growth in negative electrode impedance reflects changes in the SEI layer. Our results indicate that cell performance loss could be mitigated by modifying the electrode-electrolyte interfaces through use of appropriate electrode coatings and/or electrolyte additives.« less

The Measurement, Nomological Net, and Theory of Perceived Self-Esteem Instability: Applying the Conservation of Resources Theory to Understand the Construct.

PubMed

Howard, Matt C

2018-01-01

The current article performs the first focused investigation into the construct of perceived self-esteem instability (P-SEI). Four studies investigate the construct's measurement, nomological net, and theoretical dynamics. Study 1 confirms the factor structure of a P-SEI Measure, supporting that P-SEI can be adequately measured. Study 2 identifies an initial nomological net surrounding P-SEI, showing that the construct is strongly related to stable aspects of the self (i.e., neuroticism and core self-evaluations). In Studies 3 and 4, the Conservation of Resources Theory is applied to develop and test five hypotheses. These studies show that P-SEI is predicted by self-esteem level and stressors, and the relationship of certain stressors is moderated by self-esteem contingencies. P-SEI also predicts stress, depression, anxiety, and certain defensive postures. From these studies and the integration of Conservation of Resources Theory, we suggest that P-SEI emerges through an interaction between environmental influences and personal resources, and we provide a theoretical model to better understand the construct of P-SEI. We suggest that this theory-driven model can prompt the initial field of study on P-SEI.

Enhancing cycling durability of Li-ion batteries with hierarchical structured silicon-graphene hybrid anodes.

PubMed

Loveridge, Melanie J; Lain, Michael J; Huang, Qianye; Wan, Chaoying; Roberts, Alexander J; Pappas, George S; Bhagat, Rohit

2016-11-09

Hybrid anode materials consisting of micro-sized silicon (Si) particles interconnected with few-layer graphene (FLG) nanoplatelets and sodium-neutralized poly(acrylic acid) as a binder were evaluated for Li-ion batteries. The hybrid film has demonstrated a reversible discharge capacity of ∼1800 mA h g -1 with a capacity retention of 97% after 200 cycles. The superior electrochemical properties of the hybrid anodes are attributed to a durable, hierarchical conductive network formed between Si particles and the multi-scale carbon additives, with enhanced cohesion by the functional polymer binder. Furthermore, improved solid electrolyte interphase (SEI) stability is achieved from the electrolyte additives, due to the formation of a kinetically stable film on the surface of the Si.

76 FR 72729 - SEI Investments Management Corporation, et al.

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-25

...] SEI Investments Management Corporation, et al. November 18, 2011. AGENCY: Securities and Exchange... Application: Applicants request an order to permit open-end management investment companies relying on rule 12d1-2 under the Act to invest in certain financial instruments. Applicants: SEI Investments Management...

A parametric study of non-thermal plasma synthesis of silicon nanoparticles from a chlorinated precursor

NASA Astrophysics Data System (ADS)

Ding, Yi; Yamada, Riku; Gresback, Ryan; Zhou, Shu; Pi, Xiaodong; Nozaki, Tomohiro

2014-12-01

Silicon nanoparticles (Si NPs) synthesized in non-thermal plasma with silicon tetrachloride (SiCl4) are anticipated as a non-toxic and inexpensive Si source for important applications. This study examines the crystallinity, yield, and size distribution of Si NPs in terms of specific energy input (SEI) for 2.5-65 J cm‒3 and the H2/SiCl4 ratio (1-10). The particle growth mechanism is discussed comprehensively. Atomic hydrogen (H) production using non-thermal plasma is the primary important step for SiCl4 dechlorination at low temperatures. The Si NP yield increases with SEI (plasma power divided by total gas flow) because SiCl4 conversion increases with energy fed into the unit volume of the feed gas. At low SEI, Si NPs were mostly in amorphous material because of insufficient plasma heating. A maximum yield of 50 wt% was obtained when SEI = 10 J cm‒3 (H2/SiCl4 = 10) with a crystal fraction of about 1%. Increased SEI is necessary to improve crystal fraction, but excessive SEI decreases the NP yield remarkably. The NP yield losses correspond to increasing NP-free thin film growth on the reactor wall. Mass spectrometry shows that SiCl4 is highly decomposed with greater SEI. Hydrogen chloride (HCl) increases as a by-product. At higher SEI, particle nucleation and subsequent growth are suppressed.

CMMI on the Web: Remastered

DTIC Science & Technology

2009-09-01

Patrick Kirwin: www.sei.cmu.edu/library/abstracts/webinars/18jul2008.cfm  Also see: www.sei.cmu.edu/prime  ISO 9001/15504/ 12207 /15288 Process...Improvement with CMMI V1.2 and ISO Standards by Boris Mutafelija and Harvey Stromberg (Book)  www.sei.cmu.edu/library/abstracts/presentations/Mutafelija

Free-standing Fe2O3 nanomembranes enabling ultra-long cycling life and high rate capability for Li-ion batteries.

PubMed

Liu, Xianghong; Si, Wenping; Zhang, Jun; Sun, Xiaolei; Deng, Junwen; Baunack, Stefan; Oswald, Steffen; Liu, Lifeng; Yan, Chenglin; Schmidt, Oliver G

2014-12-12

With Fe2O3 as a proof-of-concept, free-standing nanomembrane structure is demonstrated to be highly advantageous to improve the performance of Li-ion batteries. The Fe2O3 nanomembrane electrodes exhibit ultra-long cycling life at high current rates with satisfactory capacity (808 mAh g(-1) after 1000 cycles at 2 C and 530 mAh g(-1) after 3000 cycles at 6 C) as well as repeatable high rate capability up to 50 C. The excellent performance benefits particularly from the unique structural advantages of the nanomembranes. The mechanical feature can buffer the strain of lithiation/delithiation to postpone the pulverization. The two-dimensional transport pathways in between the nanomembranes can promote the pseudo-capacitive type storage. The parallel-laid nanomembranes, which are coated by polymeric gel-like film and SEI layer with the electrolyte in between layers, electrochemically behave like numerous "mini-capacitors" to provide the pseudo-capacitance thus maintain the capacity at high rate.

In Situ Study of Silicon Electrode Lithiation with X-ray Reflectivity

DOE PAGES

Cao, Chuntian; Steinrück, Hans-Georg; Shyam, Badri; ...

2016-10-26

Surface sensitive X-ray reflectivity (XRR) measurements were performed to investigate the electrochemical lithiation of a native oxide terminated single crystalline silicon (100) electrode in real time during the first galvanostatic discharge cycle. This allows us to gain nanoscale, mechanistic insight into the lithiation of Si and the formation of the solid electrolyte interphase (SEI). We describe an electrochemistry cell specifically designed for in situ XRR studies and have determined the evolution of the electron density profile of the lithiated Si layer (Li xSi) and the SEI layer with subnanometer resolution. We propose a three-stage lithiation mechanism with a reaction limited,more » layer-by-layer lithiation of the Si at the Li xSi/Si interface.« less

Risk management for the Space Exploration Initiative

NASA Technical Reports Server (NTRS)

Buchbinder, Ben

1993-01-01

Probabilistic Risk Assessment (PRA) is a quantitative engineering process that provides the analytic structure and decision-making framework for total programmatic risk management. Ideally, it is initiated in the conceptual design phase and used throughout the program life cycle. Although PRA was developed for assessment of safety, reliability, and availability risk, it has far greater application. Throughout the design phase, PRA can guide trade-off studies among system performance, safety, reliability, cost, and schedule. These studies are based on the assessment of the risk of meeting each parameter goal, with full consideration of the uncertainties. Quantitative trade-off studies are essential, but without full identification, propagation, and display of uncertainties, poor decisions may result. PRA also can focus attention on risk drivers in situations where risk is too high. For example, if safety risk is unacceptable, the PRA prioritizes the risk contributors to guide the use of resources for risk mitigation. PRA is used in the Space Exploration Initiative (SEI) Program. To meet the stringent requirements of the SEI mission, within strict budgetary constraints, the PRA structure supports informed and traceable decision-making. This paper briefly describes the SEI PRA process.

Skin exposure to aliphatic polyisocyanates in the auto body repair and refinishing industry: III. A personal exposure algorithm.

PubMed

Liu, Youcheng; Stowe, Meredith H; Bello, Dhimiter; Sparer, Judy; Gore, Rebecca J; Cullen, Mark R; Redlich, Carrie A; Woskie, Susan R

2009-01-01

Isocyanate skin exposure may play an important role in sensitization and the development of isocyanate asthma, but such exposures are frequently intermittent and difficult to assess. Exposure metrics are needed to better estimate isocyanate skin exposures. The goal of this study was to develop a semiquantitative algorithm to estimate personal skin exposures in auto body shop workers using task-based skin exposure data and daily work diaries. The relationship between skin and respiratory exposure metrics was also evaluated. The development and results of respiratory exposure metrics were previously reported. Using the task-based data obtained with a colorimetric skin exposure indicator and a daily work diary, we developed a skin exposure algorithm to estimate a skin exposure index (SEI) for each worker. This algorithm considered the type of personal protective equipment (PPE) used, the percentage of skin area covered by PPE and skin exposures without and underneath the PPE. The SEI was summed across the day (daily SEI) and survey week (weekly average SEI) for each worker, compared among the job title categories and also compared with the respiratory exposure metrics. A total of 893 person-days was calculated for 232 workers (49 painters, 118 technicians and 65 office workers) from 33 auto body shops. The median (10th-90th percentile, maximum) daily SEI was 0 (0-0, 1.0), 0 (0-1.9, 4.8) and 1.6 (0-3.5, 6.1) and weekly average SEI was 0 (0-0.0, 0.7), 0.3 (0-1.6, 4.2) and 1.9 (0.4-3.0, 3.6) for office workers, technicians and painters, respectively, which were significantly different (P < 0.0001). The median (10th-90th percentile, maximum) daily SEI was 0 (0-2.4, 6.1) and weekly average SEI was 0.2 (0-2.3, 4.2) for all workers. A relatively weak positive Spearman correlation was found between daily SEI and time-weighted average (TWA) respiratory exposure metrics (microg NCO m(-3)) (r = 0.380, n = 893, P < 0.0001) and between weekly SEI and TWA respiratory exposure metrics (r = 0.482, n = 232, P < 0.0001). The skin exposure algorithm developed in this study provides task-based personal daily and weekly average skin exposure indices that are adjusted for the use of PPE. These skin exposure indices can be used to assess isocyanate exposure-response relationships.

Ionic liquid electrolytes for Li-air batteries: lithium metal cycling.

PubMed

Grande, Lorenzo; Paillard, Elie; Kim, Guk-Tae; Monaco, Simone; Passerini, Stefano

2014-05-08

In this work, the electrochemical stability and lithium plating/stripping performance of N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI) are reported, by investigating the behavior of Li metal electrodes in symmetrical Li/electrolyte/Li cells. Electrochemical impedance spectroscopy measurements and galvanostatic cycling at different temperatures are performed to analyze the influence of temperature on the stabilization of the solid electrolyte interphase (SEI), showing that TFSI-based ionic liquids (ILs) rank among the best candidates for long-lasting Li-air cells.

Ionic Liquid Electrolytes for Li–Air Batteries: Lithium Metal Cycling

PubMed Central

Grande, Lorenzo; Paillard, Elie; Kim, Guk-Tae; Monaco, Simone; Passerini, Stefano

2014-01-01

In this work, the electrochemical stability and lithium plating/stripping performance of N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI) are reported, by investigating the behavior of Li metal electrodes in symmetrical Li/electrolyte/Li cells. Electrochemical impedance spectroscopy measurements and galvanostatic cycling at different temperatures are performed to analyze the influence of temperature on the stabilization of the solid electrolyte interphase (SEI), showing that TFSI-based ionic liquids (ILs) rank among the best candidates for long-lasting Li–air cells. PMID:24815072

An Initial Comparative Analysis of the CMMI Version 1.2 Development Constellation and the ISO 9000 Family

DTIC Science & Technology

2009-03-01

www.loc.gov/catdir/toc/els031/2002038518.html [ Humphrey 1987] Watts S . Humphrey . Characterizing the Software Process: A Maturity Framework (CMU/SEI...five-stage organizational maturity scale developed by the SEI and first described in an SEI technical report authored by Watts Humphrey in 1987... Humphrey 1987]. In 2007, an additional model was released (CMMI for Acquisition, V1.2), but this technical report focuses only on CMMI-DEV, V1.2. In

75 FR 39577 - Draft Supplemental Environmental Impact Statement on the Issuance of Annual Regulations...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-09

... timing of the general regulatory process. (2) Frequency of review and adoption of duck regulatory packages. Duck regulatory packages are the set of framework regulations that apply to the general duck... limits), and closed. In the draft SEIS, we present two alternatives regarding how frequently duck...

A Bibliography of the Personal Software Process (PSP) and the Team Software Process (TSP)

DTIC Science & Technology

2009-10-01

Postmortem.‖ Proceedings of the TSP Symposium (September 2007). http://www.sei.cmu.edu/tspsymposium/ Rickets , Chris; Lindeman, Robert; & Hodgins, Brad... Rickets , Chris A. ―A TSP Software Maintenance Life Cycle.‖ CrossTalk (March 2005). Rozanc, I. & Mahnic, V. ―Teaching Software Quality with Emphasis on PSP

Argonne Chemical Sciences & Engineering - Center for Electrical Energy

Science.gov Websites

electrodes at the SEI interface, Li-ion batteries show limited calendar and cycle life--less than 2 years energy storage requirements. The CEES will focus on lithium batteries, as they offer the best opportunity of Argonne's Applied Battery Research and Development Program. EFRCs at Argonne The Center for

Graphene Oxides Used as a New "Dual Role" Binder for Stabilizing Silicon Nanoparticles in Lithium-Ion Battery.

PubMed

Shan, Changsheng; Wu, Kaifeng; Yen, Hung-Ju; Narvaez Villarrubia, Claudia; Nakotte, Tom; Bo, Xiangjie; Zhou, Ming; Wu, Gang; Wang, Hsing-Lin

2018-05-09

For the first time, we report that graphene oxide (GO) can be used as a new "dual-role" binder for Si nanoparticles (SiNPs)-based lithium-ion batteries (LIBs). GO not only provides a graphene-like porous 3D framework for accommodating the volume changes of SiNPs during charging/discharging cycles, but also acts as a polymer-like binder that forms strong chemical bonds with SiNPs through its Si-OH functional groups to trap and stabilize SiNPs inside the electrode. Leveraging this unique dual-role of GO binder, we fabricated GO/SiNPs electrodes with remarkably improved performances as compared to using the conventional polyvinylidene fluoride (PVDF) binder. Specifically, the GO/SiNPs electrode showed a specific capacity of 2400 mA h g -1 at the 50th cycle and 2000 mA h g -1 at the 100th cycle, whereas the SiNPs/PVDF electrode only showed 456 mAh g -1 at the 50th cycle and 100 mAh g -1 at 100th cycle. Moreover, the GO/SiNPs film maintained its structural integrity and formed a stable solid-electrolyte interphase (SEI) film after 100 cycles. These results, combined with the well-established facile synthesis of GO, indicate that GO can be an excellent binder for developing high performance Si-based LIBs.

Two-Dimensional Porous Sandwich-Like C/Si-Graphene-Si/C Nanosheets for Superior Lithium Storage.

PubMed

Yao, Weiqi; Chen, Jie; Zhan, Liang; Wang, Yanli; Yang, Shubin

2017-11-15

A novel two-dimensional porous sandwich-like Si/carbon nanosheet is designed and successfully fabricated as an anode for superior lithium storage, where a porous Si nanofilm grows on the two sides of reduced graphene oxide (rGO) and is then coated with a carbon layer (denoted as C/Si-rGO-Si/C). The coexistence of micropores and mesopores in C/Si-rGO-Si/C nanosheets offers a rapid Li + diffusion rate, and the porous Si provides a short pathway for electric transportation. Meanwhile, the coated carbon layer not only can promote to form a stable SEI layer, but also can improve the electric conductivity of nanoscale Si coupled with rGO. Thus, the unique nanostructures offer the resultant C/Si-rGO-Si/C electrode with high reversible capacity (1187 mA h g -1 after 200 cycles at 0.2 A g -1 ), excellent cycle stability (894 mA h g -1 after 1000 cycles at 1 A g -1 ), and high rate capability (694 mA h g -1 at 5 A g -1 , 447 mA h g -1 at 10 A g -1 ).

Degradation of lithium ion batteries employing graphite negatives and nickel-cobalt-manganese oxide + spinel manganese oxide positives: Part 2, chemical-mechanical degradation model

NASA Astrophysics Data System (ADS)

Purewal, Justin; Wang, John; Graetz, Jason; Soukiazian, Souren; Tataria, Harshad; Verbrugge, Mark W.

2014-12-01

Capacity fade is reported for 1.5 Ah Li-ion batteries containing a mixture of Li-Ni-Co-Mn oxide (NCM) + Li-Mn oxide spinel (LMO) as positive electrode material and a graphite negative electrode. The batteries were cycled at a wide range of temperatures (10 °C-46 °C) and discharge currents (0.5C-6.5C). The measured capacity losses were fit to a simple physics-based model which calculates lithium inventory loss from two related mechanisms: (1) mechanical degradation at the graphite anode particle surface caused by diffusion-induced stresses (DIS) and (2) chemical degradation caused by lithium loss to continued growth of the solid-electrolyte interphase (SEI). These two mechanisms are coupled because lithium is consumed through SEI formation on newly exposed crack surfaces. The growth of crack surface area is modeled as a fatigue phenomenon due to the cyclic stresses generated by repeated lithium insertion and de-insertion of graphite particles. This coupled chemical-mechanical degradation model is consistent with the observed capacity loss features for the NCM + LMO/graphite cells.

Na2.5Fe1.75(SO4)3/Ketjen/rGO: An advanced cathode composite for sodium ion batteries

NASA Astrophysics Data System (ADS)

Goñi, A.; Iturrondobeitia, A.; Gil de Muro, I.; Lezama, L.; Rojo, T.

2017-11-01

An advanced cathode composite Na2.5Fe1.75(SO4)3/Ketjen/rGO for sodium ion batteries has been prepared, joining together the excellent electrochemical properties of the three components: off stoichiometric iron sulfate alluaudite, Ketjen Black carbon and reduced graphene oxide (rGO). This electrode material has been exhaustively characterized by XRD, thermogravimetric analysis, Raman spectroscopy and SEM and TEM microscopy. The study has demonstrated that a high quality electrode material has been designed containing a porous sulfate core properly coated by interweaved rGO fibers and Ketjen Black nanoparticles. The electrochemical study has revealed an excellent performance providing specific capacities close to the theoretical one at 1C. Additionally, this composite has shown a very good rate capability and a great cycling stability for at least 200 cycles maintaining a coulombic efficiency of 96%. The post mortem analysis, which includes EPR and XPS measurements, has demonstrated that the carbonaceous coating on the composite generates a stable and protective SEI layer over the active material guaranteeing a successful performance during a long cycle life.

Decomposition of the fluoroethylene carbonate additive and the glue effect of lithium fluoride products for the solid electrolyte interphase: an ab initio study.

PubMed

Okuno, Yukihiro; Ushirogata, Keisuke; Sodeyama, Keitaro; Tateyama, Yoshitaka

2016-03-28

Additives in the electrolyte solution of lithium-ion batteries (LIBs) have a large impact on the performance of the solid electrolyte interphase (SEI) that forms on the anode and is a key to the stability and durability of LIBs. We theoretically investigated effects of fluoroethylene carbonate (FEC), a representative additive, that has recently attracted considerable attention for the enhancement of cycling stability of silicon electrodes and the improvement of reversibility of sodium-ion batteries. First, we intensively examined the reductive decompositions by ring-opening, hydrogen fluoride (HF) elimination to form a vinylene carbonate (VC) additive and intermolecular chemical reactions of FEC in the ethylene carbonate (EC) electrolyte, by using density functional theory (DFT) based molecular dynamics and the blue-moon ensemble technique for the free energy profile. The results show that the most plausible product of the FEC reductive decomposition is lithium fluoride (LiF), and that the reactivity of FEC to anion radicals is found to be inert compared to the VC additive. We also investigated the effects of the generated LiF on the SEI by using two model systems; (1) LiF molecules distributed in a model aggregate of organic SEI film components (SFCs) and (2) a LiF aggregate interfaced with the SFC aggregate. DFT calculations of the former system show that F atoms form strong bindings with the Li atoms of multiple organic SFC molecules and play as a joint connecting them. In the latter interface system, the LiF aggregate adsorbs the organic SFCs through the F-Li bindings. These results suggest that LiF moieties play the role of glue in the organic SFC within the SEI film. We also examined the interface structure between a LiF aggregate and a lithiated silicon anode, and found that they are strongly bound. This strong binding is likely to be related to the effectiveness of the FEC additive in the electrolyte for the silicon anode.

An Ultrahigh Capacity Graphite/Li 2S Battery with Holey-Li 2S Nanoarchitectures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Fangmin; Noh, Hyungjun; Lee, Hongkyung

The pairing of high-capacity Li 2S cathode (1166 mAh g -1) and lithium-free anode (LFA) provides an unparalleled potential in developing safe and energy-dense next-generation secondary batteries. However, the low utilization of the Li 2S cathode and the lack of electrolytes compatible to both electrodes are impeding the development. Here, a novel graphite/Li 2S battery system, which features a self-assembled, holey-Li 2S nanoarchitecture and a stable solid electrolyte interface (SEI) on the graphite electrode, is reported. The holey structure on Li 2S is beneficial in decomposing Li 2S at the first charging process due to the enhanced Li ion extractionmore » and transfer from the Li 2S to the electrolyte. In addition, the concentrated dioxolane (DOL)-rich electrolyte designed lowers the irreversible capacity loss for SEI formation. By using the combined strategies, the graphite/holey-Li 2S battery delivers an ultrahigh discharge capacity of 810 mAh g -1 at 0.1 C (based on the mass of Li 2S) and of 714 mAh g -1 at 0.2 C. Moreover, it exhibits a reversible capacity of 300 mAh g -1 after a record lifecycle of 600 cycles at 1 C. These results suggest the great potential of the designed LFA/holey-Li 2S batteries for practical use.« less

An Ultrahigh Capacity Graphite/Li 2S Battery with Holey-Li 2S Nanoarchitectures

DOE PAGES

Ye, Fangmin; Noh, Hyungjun; Lee, Hongkyung; ...

2018-05-07

The pairing of high-capacity Li 2S cathode (1166 mAh g -1) and lithium-free anode (LFA) provides an unparalleled potential in developing safe and energy-dense next-generation secondary batteries. However, the low utilization of the Li 2S cathode and the lack of electrolytes compatible to both electrodes are impeding the development. Here, a novel graphite/Li 2S battery system, which features a self-assembled, holey-Li 2S nanoarchitecture and a stable solid electrolyte interface (SEI) on the graphite electrode, is reported. The holey structure on Li 2S is beneficial in decomposing Li 2S at the first charging process due to the enhanced Li ion extractionmore » and transfer from the Li 2S to the electrolyte. In addition, the concentrated dioxolane (DOL)-rich electrolyte designed lowers the irreversible capacity loss for SEI formation. By using the combined strategies, the graphite/holey-Li 2S battery delivers an ultrahigh discharge capacity of 810 mAh g -1 at 0.1 C (based on the mass of Li 2S) and of 714 mAh g -1 at 0.2 C. Moreover, it exhibits a reversible capacity of 300 mAh g -1 after a record lifecycle of 600 cycles at 1 C. These results suggest the great potential of the designed LFA/holey-Li 2S batteries for practical use.« less

76 FR 60017 - Notice of Intent To Prepare a Supplemental Environmental Impact Statement (SEIS) for the...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-28

..., irradiation will increase from today's 544 TPBARs per fuel cycle to a projected steady state rate of... requesting authorization for TPBAR irradiation to be increased in fiscal year 2016 to a level that is beyond... the Nuclear Regulatory Commission (NRC) to permit the irradiation of a greater number of TPBARs per...

Ilmenite Nanotubes for High Stability and High Rate Sodium-Ion Battery Anodes.

PubMed

Yu, Litao; Liu, Jun; Xu, Xijun; Zhang, Liguo; Hu, Renzong; Liu, Jiangwen; Ouyang, Liuzhang; Yang, Lichun; Zhu, Min

2017-05-23

To solve the problem of large volume change and low electronic conductivity of earth-abundant ilmenite used in rechargeable Na-ion batteries (SIBs), an anode of tiny ilmenite FeTiO 3 nanoparticle embedded carbon nanotubes (FTO⊂CNTs) has been successfully proposed. By introducing a TiO 2 shell on metal-organic framework (Fe-MOF) nanorods by sol-gel deposition and subsequent solid-state annealing treatment of these core-shell Fe-MOF@TiO 2 , such well-defined FTO⊂CNTs are obtained. The achieved FTO⊂CNT electrode has several distinct advantages including a hollow interior in the hybrid nanostructure, fully encapsulated ultrasmall electroactive units, flexible conductive carbon matrix, and stable solid electrolyte interface (SEI) of FTO in cycles. FTO⊂CNT electrodes present an excellent cycle stability (358.8 mA h g -1 after 200 cycles at 100 mA g -1 ) and remarkable rate capability (201.8 mA h g -1 at 5000 mA g -1 ) with a high Coulombic efficiency of approximately 99%. In addition, combined with the typical Na 3 V 2 (PO 4 ) 3 cathode to constitute full SIBs, the assembled FTO⊂CNT//Na 3 V 2 (PO 4 ) 3 batteries are also demonstrated with superior rate capability and a long cycle life.

Understanding and improving lithium ion batteries through mathematical modeling and experiments

NASA Astrophysics Data System (ADS)

Deshpande, Rutooj D.

There is an intense, worldwide effort to develop durable lithium ion batteries with high energy and power densities for a wide range of applications, including electric and hybrid electric vehicles. For improvement of battery technology understanding the capacity fading mechanism in batteries is of utmost importance. Novel electrode material and improved electrode designs are needed for high energy- high power batteries with less capacity fading. Furthermore, for applications such as automotive applications, precise cycle-life prediction of batteries is necessary. One of the critical challenges in advancing lithium ion battery technologies is fracture and decrepitation of the electrodes as a result of lithium diffusion during charging and discharging operations. When lithium is inserted in either the positive or negative electrode, there is a volume change associated with insertion or de-insertion. Diffusion-induced stresses (DISs) can therefore cause the nucleation and growth of cracks, leading to mechanical degradation of the batteries. With different mathematical models we studied the behavior of diffusion induces stresses and effects of electrode shape, size, concentration dependent material properties, pre-existing cracks, phase transformations, operating conditions etc. on the diffusion induced stresses. Thus we develop tools to guide the design of the electrode material with better mechanical stability for durable batteries. Along with mechanical degradation, chemical degradation of batteries also plays an important role in deciding battery cycle life. The instability of commonly employed electrolytes results in solid electrolyte interphase (SEI) formation. Although SEI formation contributes to irreversible capacity loss, the SEI layer is necessary, as it passivates the electrode-electrolyte interface from further solvent decomposition. SEI layer and diffusion induced stresses are inter-dependent and affect each-other. We study coupled chemical-mechanical degradation of electrode materials to understand the capacity fading of the battery with cycling. With the understanding of chemical and mechanical degradation, we develop a simple phenomenological model to predict battery life. On the experimental part we come up with a novel concept of using liquid metal alloy as a self-healing battery electrode. We develop a method to prepare thin film liquid gallium electrode on a conductive substrate. This enabled us to perform a series of electrochemical and characterization experiments which certify that liquid electrode undergo liquid-solid-liquid transition and thus self-heals the cracks formed during de-insertion. Thus the mechanical degradation can be avoided. We also perform ab-initio calculations to understand the equilibrium potential of various lithium-gallium phases. KEYWORDS: Lithium ion batteries, diffusion induced stresses, self-healing electrode, coupled chemical and mechanical degradation, life-prediction model.

Season-Ending Shoulder Injuries in the National Collegiate Athletic Association: Data From the NCAA Injury Surveillance Program, 2009-2010 Through 2013-2014.

PubMed

Goodman, Avi D; DeFroda, Steven F; Gil, Joseph A; Kleiner, Justin E; Li, Neill Y; Owens, Brett D

2018-05-01

Examination of the incidence of shoulder season-ending injury (SEI) in the collegiate athlete population is limited. To determine the incidence of shoulder SEI in the National Collegiate Athletic Association (NCAA) and to investigate the risk factors for a shoulder injury ending an athlete's season. Descriptive epidemiology study. All shoulder injuries from the NCAA Injury Surveillance Program database for the years 2009-2010 to 2013-2014 were extracted, and SEI status was noted. The incidences of SEI and non-SEI were calculated for athlete, activity, and injury characteristics and compared via univariable analysis and risk ratios to determine risk factors for an injury being season ending. Shoulder injuries were season ending in 4.3% of cases. The overall incidence of shoulder SEI was 0.31 per 10,000 athlete exposures (AEs), as opposed to 7.25 per 10,000 AEs for all shoulder injuries. Shoulder instability constituted 49.1% of SEI, with an incidence of 0.15 per 10,000 AEs, while fractures had the highest rate of being season ending (41.9%). Men's wrestling had the highest incidence of shoulder SEI (1.65 per 10,000 AEs), while men's soccer had the highest proportion of shoulder injuries that ended a season (14.6%). Overall, men had a 6.3-fold higher incidence of SEI than women and a 2.4-fold increased likelihood that an injury would be season ending. Injury to the shoulder of an NCAA athlete, while somewhat infrequent, can have significant implications on time lost from play. Incidence of these injuries varies widely by sport and injury, with a number of associated risk factors. Athletes sustaining potentially season-ending shoulder injuries, with their coaches and medical providers, may benefit from these data to best manage expectations and outcomes.

Effect of Vinylene Carbonate and Fluoroethylene Carbonate on SEI Formation on Graphitic Anodes in Li-Ion Batteries

DOE PAGES

Nie, Mengyun; Demeaux, Julien; Young, Benjamin T.; ...

2015-07-23

Binder free (BF) graphite electrodes were utilized to investigate the effect of electrolyte additives fluoroethylene carbonate (FEC) and vinylene carbonate (VC) on the structure of the solid electrolyte interface (SEI). The structure of the SEI has been investigated via ex-situ surface analysis including X-ray Photoelectron spectroscopy (XPS), Hard XPS (HAXPES), Infrared spectroscopy (IR) and transmission electron microscopy (TEM). The components of the SEI have been further investigated via nuclear magnetic resonance (NMR) spectroscopy of D2O extractions. The SEI generated on the BF-graphite anode with a standard electrolyte (1.2 M LiPF6 in ethylene carbonate (EC) / ethyl methyl carbonate (EMC), 3/7more » (v/v)) is composed primarily of lithium alkyl carbonates (LAC) and LiF. Incorporation of VC (3% wt) results in the generation of a thinner SEI composed of Li2CO3, poly(VC), LAC, and LiF. Incorporation of VC inhibits the generation of LAC and LiF. Incorporation of FEC (3% wt) also results in the generation of a thinner SEI composed of Li2CO3, poly(FEC), LAC, and LiF. The concentration of poly(FEC) is lower than the concentration of poly(VC) and the generation of LAC is inhibited in the presence of FEC. The SEI appears to be a homogeneous film for all electrolytes investigated.« less

Reuse Adoption Guidebook. Version 02.00.05

DTIC Science & Technology

1993-11-01

Oriented Domain Analysis ( FODA ) Feasibiity Study, W Novak, and S. Peterson CMU/SEI-90-TR-21 Pittsburgh, Pennsylvania: Software 1990 Engineering Institute...Mettala and Graham 1992). " SEI has developed domain analysis techniques (Kang et al. 1990) and other reuse technology. Additionally, the SEI is in the...continue to build on your success. Figure 2-1 illustrates the Reuse Adoption process using a Structured Analysis and Design Thchmque (SADT) diagram

N-Allyl- N, N-Bis(trimethylsilyl)amine as a Novel Electrolyte Additive To Enhance the Interfacial Stability of a Ni-Rich Electrode for Lithium-Ion Batteries.

PubMed

Zheng, Qinfeng; Xing, Lidan; Yang, Xuerui; Li, Xiangfeng; Ye, Changchun; Wang, Kang; Huang, Qiming; Li, Weishan

2018-05-16

Enhancing the electrode/electrolyte interface stability of high-capacity LiNi 0.8 Co 0.15 Al 0.05 O 2 (LNCA) cathode material is urgently required for its application in next-generation lithium-ion battery. Herein, we demonstrate that enhanced interfacial stability of LNCA can be achieved by simply introducing 2 wt % N-allyl- N, N-bis(trimethylsilyl)amine (NNB) electrolyte additive. Electrolyte oxidation reactions and electrode structural destruction are greatly suppressed in the electrolyte with NNB additive, leading to improved cyclic stability of LNCA from 72.8 to 86.2% after 300 cycles. The mechanism of NNB on improving the cyclic stability of LNCA has been verified to its excellent solid electrolyte interface (SEI) film-forming capability. Moreover, the X-ray diffraction and X-ray photoelectron spectroscopy results indicate that the NNB-derived Si-containing SEI film restrains the Li/Ni disorder of LNCA during cycling, which further improves the cyclic stability of Ni-rich LNCA. Importantly, the charging/discharging test reveals that the NNB additive effectively improves the cyclic stability of the LNCA/graphite full cell.

Gas swelling behaviour at different stages in Li4Ti5O12/LiNi1/3Co1/3Mn1/3O2 pouch cells

NASA Astrophysics Data System (ADS)

Liu, Wei; Liu, Haohan; Wang, Qian; Zhang, Jian; Xia, Baojia; Min, Guoquan

2017-11-01

Gas swelling behaviour is a major drawback of batteries that are based on Li4Ti5O12 anode materials and hinders their application. In this article, the morphology and electronic structure changes of Li4Ti5O12 electrodes at ageing and cycling stages are investigated using scanning electron microscopy, X-ray absorption near-edge structure and X-ray photoelectron spectroscopy. A simple method that uses an air bag to collect the generated gases was conducted and the gases were then characterised by gas chromatography/mass spectrometry. The results indicate that the charge transformation of Ti ions would aggravate the gas swelling behaviour. The solid electrolyte interphase (SEI) films form on the surface of the Li4Ti5O12 particles and become thicker with increasing charge state. The gas components change significantly during the ageing and cycling, indicating the complexity of the gas swelling mechanism.

Engineering empty space between Si nanoparticles for lithium-ion battery anodes.

PubMed

Wu, Hui; Zheng, Guangyuan; Liu, Nian; Carney, Thomas J; Yang, Yuan; Cui, Yi

2012-02-08

Silicon is a promising high-capacity anode material for lithium-ion batteries yet attaining long cycle life remains a significant challenge due to pulverization of the silicon and unstable solid-electrolyte interphase (SEI) formation during the electrochemical cycles. Despite significant advances in nanostructured Si electrodes, challenges including short cycle life and scalability hinder its widespread implementation. To address these challenges, we engineered an empty space between Si nanoparticles by encapsulating them in hollow carbon tubes. The synthesis process used low-cost Si nanoparticles and electrospinning methods, both of which can be easily scaled. The empty space around the Si nanoparticles allowed the electrode to successfully overcome these problems Our anode demonstrated a high gravimetric capacity (~1000 mAh/g based on the total mass) and long cycle life (200 cycles with 90% capacity retention). © 2012 American Chemical Society

A contrastive study of three graphite anodes in the piperidinium based electrolytes for lithium ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Xiao-Tao; Wang, Chen-Yi; Gao, Kun, E-mail: gaokun0451@163.com

Graphical abstract: The fitting results of R{sub sei} and R{sub ct} of three graphite/Li cells. Besides three graphite/Li cells show the similar R{sub sei}, the NG198/Li cell demonstrates a higher R{sub ct} value in all test temperatures. Especially, the R{sub ct} at 333 K is even up to 355.8 Ω cm{sup 2}. Obviously, the narrow distribution of edge plane for NG198 caused this result, and then greatly restricts its cell capacity. By contrast, CMB with bigger specific surface area and more Li{sup +} insertion points shows lower resistance at room temperature, which should help to improve its capacity. - Highlights:more » • SEI film is closely related to graphite structures and formation temperature. • The graphite with bigger surface area and more Li{sup +} insertion points behaves better. • The graphite with narrow edge plane is uncompetitive for ionic liquid electrolyte. - Abstract: The electrochemical behaviors of natural graphite (NG198), artificial graphite (AG360) and carbon microbeads (CMB) in an ionic liquid based electrolyte are investigated by cyclic voltammetry (CV). The surface and structure of three graphite materials are characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD) before and after cycling. It is found that solid electrolyte interface (SEI) is closely related to graphite structure. Benefiting from larger specific surface area and more dispersed Li{sup +} insertion points, CMB shows a better Li{sup +} insertion/de-insertion behavior than NG198 and AG360. Furthermore, electrochemical impedance spectra (EIS) prove that the SEI of different graphite electrodes has different intrinsic resistance and Li{sup +} penetrability. By comparison, CMB behaves better cell performances than AG360, while the narrow edge plane makes NG198 uncompetitive as a potential anode for the ionic liquids (ILs)-type Li-ion battery.« less

Software Engineering Institute, Annual Report 2001

DTIC Science & Technology

2002-03-01

PSP and TSP written by Watts S . Humphrey for the Addison- Wesley SEI Series in...become SCAMPI Lead Assessors. SEI A n n u a l R epo r t fy20 0 1 • 25 CMM Pioneer: Watts S . Humphrey The effort to create the original concepts of the SW...CMM was led by SEI Fellow Watts S . Humphrey , who has had a profound impact on the field of software engineering. In February 2000, a new

Selecting the Best Graphite for Long-Life, High-Energy Li-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mao, Chengyu; Wood, Marissa; David, Lamuel Abraham

Here, most lithium-ion batteries still rely on intercalation-type graphite materials for anodes, so it is important to consider their role in full cells for applications in electric vehicles. Here, we systematically evaluate the chemical and physical properties of six commercially-available natural and synthetic graphites to establish which factors have the greatest impact on the cycling stability of full cells with nickel-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes. Electrochemical data and post-mortem characterization explain the origin of capacity fade. The NMC811 cathode shows large irreversible capacity loss and impedance growth, accounting for much of full cell degradation. However, six graphite anodes demonstrate significant differencesmore » with respect to structural change, surface area, impedance growth, and SEI chemistry, which impact overall capacity retention. We found long cycle life correlated most strongly with stable graphite crystallite size. In addition, graphites with lower surface area generally had higher coulombic efficiencies during formation cycles, which led to more stable long-term cycling. The best graphite screened here enables a capacity retention around 90% in full pouch cells over extensive long-term cycling compared to only 82% for cells with the lowest performing graphite. The results show that optimal graphite selection improves cycling stability of high energy lithium-ion cells.« less

Selecting the Best Graphite for Long-Life, High-Energy Li-Ion Batteries

DOE PAGES

Mao, Chengyu; Wood, Marissa; David, Lamuel Abraham; ...

2018-06-16

Here, most lithium-ion batteries still rely on intercalation-type graphite materials for anodes, so it is important to consider their role in full cells for applications in electric vehicles. Here, we systematically evaluate the chemical and physical properties of six commercially-available natural and synthetic graphites to establish which factors have the greatest impact on the cycling stability of full cells with nickel-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes. Electrochemical data and post-mortem characterization explain the origin of capacity fade. The NMC811 cathode shows large irreversible capacity loss and impedance growth, accounting for much of full cell degradation. However, six graphite anodes demonstrate significant differencesmore » with respect to structural change, surface area, impedance growth, and SEI chemistry, which impact overall capacity retention. We found long cycle life correlated most strongly with stable graphite crystallite size. In addition, graphites with lower surface area generally had higher coulombic efficiencies during formation cycles, which led to more stable long-term cycling. The best graphite screened here enables a capacity retention around 90% in full pouch cells over extensive long-term cycling compared to only 82% for cells with the lowest performing graphite. The results show that optimal graphite selection improves cycling stability of high energy lithium-ion cells.« less

Spontaneous evaluative inferences and their relationship to spontaneous trait inferences.

PubMed

Schneid, Erica D; Carlston, Donal E; Skowronski, John J

2015-05-01

Three experiments are reported that explore affectively based spontaneous evaluative impressions (SEIs) of stimulus persons. Experiments 1 and 2 used modified versions of the savings in relearning paradigm (Carlston & Skowronski, 1994) to confirm the occurrence of SEIs, indicating that they are equivalent whether participants are instructed to form trait impressions, evaluative impressions, or neither. These experiments also show that SEIs occur independently of explicit recall for the trait implications of the stimuli. Experiment 3 provides a single dissociation test to distinguish SEIs from spontaneous trait inferences (STIs), showing that disrupting cognitive processing interferes with a trait-based prediction task that presumably reflects STIs, but not with an affectively based social approach task that presumably reflects SEIs. Implications of these findings for the potential independence of spontaneous trait and evaluative inferences, as well as limitations and important steps for future study are discussed. (c) 2015 APA, all rights reserved).

Review on modeling of the anode solid electrolyte interphase (SEI) for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wang, Aiping; Kadam, Sanket; Li, Hong; Shi, Siqi; Qi, Yue

2018-03-01

A passivation layer called the solid electrolyte interphase (SEI) is formed on electrode surfaces from decomposition products of electrolytes. The SEI allows Li+ transport and blocks electrons in order to prevent further electrolyte decomposition and ensure continued electrochemical reactions. The formation and growth mechanism of the nanometer thick SEI films are yet to be completely understood owing to their complex structure and lack of reliable in situ experimental techniques. Significant advances in computational methods have made it possible to predictively model the fundamentals of SEI. This review aims to give an overview of state-of-the-art modeling progress in the investigation of SEI films on the anodes, ranging from electronic structure calculations to mesoscale modeling, covering the thermodynamics and kinetics of electrolyte reduction reactions, SEI formation, modification through electrolyte design, correlation of SEI properties with battery performance, and the artificial SEI design. Multi-scale simulations have been summarized and compared with each other as well as with experiments. Computational details of the fundamental properties of SEI, such as electron tunneling, Li-ion transport, chemical/mechanical stability of the bulk SEI and electrode/(SEI/) electrolyte interfaces have been discussed. This review shows the potential of computational approaches in the deconvolution of SEI properties and design of artificial SEI. We believe that computational modeling can be integrated with experiments to complement each other and lead to a better understanding of the complex SEI for the development of a highly efficient battery in the future.

Mussel-Inspired Polydopamine Coating for Enhanced Thermal Stability and Rate Performance of Graphite Anodes in Li-Ion Batteries.

PubMed

Park, Seong-Hyo; Kim, Hyeon Jin; Lee, Junmin; Jeong, You Kyeong; Choi, Jang Wook; Lee, Hochun

2016-06-08

Despite two decades of commercial history, it remains very difficult to simultaneously achieve both high rate capability and thermal stability in the graphite anodes of Li-ion batteries because the stable solid electrolyte interphase (SEI) layer, which is essential for thermal stability, impedes facile Li(+) ion transport at the interface. Here, we resolve this longstanding challenge using a mussel-inspired polydopamine (PD) coating via a simple immersion process. The nanometer-thick PD coating layer allows the formation of an SEI layer on the coating surface without perturbing the intrinsic properties of the SEI layer of the graphite anodes. PD-coated graphite exhibits far better performances in cycling test at 60 °C and storage test at 90 °C than bare graphite. The PD-coated graphite also displays superior rate capability during both lithiation and delithiation. As evidenced by surface free energy analysis, the enhanced performance of the PD-coated graphite can be ascribed to the Lewis basicity of the PD, which scavenges harmful hydrofluoric acid and forms an intermediate triple-body complex among a Li(+) ion, solvent molecules, and the PD's basic site. The usefulness of the proposed PD coating can be expanded to various electrodes in rechargeable batteries that suffer from poor thermal stability and interfacial kinetics.

Electrolyte Chemistry for Simultaneous Stabilization of Potassium Metal and Superoxide in K-O₂ Batteries.

PubMed

Xiao, Neng; Gourdin, Gerald; Wu, Yiying

2018-05-22

In the superoxide batteries based on O2/O2- redox chemistry, identifying an electrolyte to stabilize both alkali metal and superoxide remains challenging due to their reactivity towards electrolyte components. Bis(fluorosulfonyl)imide (FSI-) has been recognized as a "magical anion" for passivating alkali metals. Herein, we illustrate the chemical reactions between FSI- and superoxide, and the resultant dilemma when considering an anode-compatible electrolyte vs. a cathode-compatible one in K-O2 batteries. On one side, the KFSI-dimethoxyethane (DME) electrolyte passivates the potassium metal anode via the cleavage of S-F bond and formation of a KF-rich solid electrolyte interface (SEI). Nevertheless, the KFSI salt is chemically unstable due to the nucleophilic attack by superoxide and/or hydroxide species. On the other hand, potassium bis(trifluorosulfonyl)imide (KTFSI) is stable for KO2, but results in mossy deposition and irreversible plating and stripping. In order to circumvent this dilemma, we develop an artificial SEI for K metal anode to achieve long cycle-life K-O2 batteries. This work contributes to the understanding of electrolyte chemistry and guides the development of stable electrolytes and artificial SEI in metal-O2 batteries. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nuclear thermal propulsion transportation systems for lunar/Mars exploration

NASA Technical Reports Server (NTRS)

Clark, John S.; Borowski, Stanley K.; Mcilwain, Melvin C.; Pellaccio, Dennis G.

1992-01-01

Nuclear thermal propulsion technology development is underway at NASA and DoE for Space Exploration Initiative (SEI) missions to Mars, with initial near-earth flights to validate flight readiness. Several reactor concepts are being considered for these missions, and important selection criteria will be evaluated before final selection of a system. These criteria include: safety and reliability, technical risk, cost, and performance, in that order. Of the concepts evaluated to date, the Nuclear Engine for Rocket Vehicle Applications (NERVA) derivative (NDR) is the only concept that has demonstrated full power, life, and performance in actual reactor tests. Other concepts will require significant design work and must demonstrate proof-of-concept. Technical risk, and hence, development cost should therefore be lowest for the concept, and the NDR concept is currently being considered for the initial SEI missions. As lighter weight, higher performance systems are developed and validated, including appropriate safety and astronaut-rating requirements, they will be considered to support future SEI application. A space transportation system using a modular nuclear thermal rocket (NTR) system for lunar and Mars missions is expected to result in significant life cycle cost savings. Finally, several key issues remain for NTR's, including public acceptance and operational issues. Nonetheless, NTR's are believed to be the 'next generation' of space propulsion systems - the key to space exploration.

An activity-based methodology for operations cost analysis

NASA Technical Reports Server (NTRS)

Korsmeyer, David; Bilby, Curt; Frizzell, R. A.

1991-01-01

This report describes an activity-based cost estimation method, proposed for the Space Exploration Initiative (SEI), as an alternative to NASA's traditional mass-based cost estimation method. A case study demonstrates how the activity-based cost estimation technique can be used to identify the operations that have a significant impact on costs over the life cycle of the SEI. The case study yielded an operations cost of $101 billion for the 20-year span of the lunar surface operations for the Option 5a program architecture. In addition, the results indicated that the support and training costs for the missions were the greatest contributors to the annual cost estimates. A cost-sensitivity analysis of the cultural and architectural drivers determined that the length of training and the amount of support associated with the ground support personnel for mission activities are the most significant cost contributors.

Beneficial effect of added water on sodium metal cycling in super concentrated ionic liquid sodium electrolytes

NASA Astrophysics Data System (ADS)

Basile, Andrew; Ferdousi, Shammi A.; Makhlooghiazad, Faezeh; Yunis, Ruhamah; Hilder, Matthias; Forsyth, Maria; Howlett, Patrick C.

2018-03-01

The plating and stripping performance of sodium metal in an ionic liquid electrolyte is improved when including water as an additive. Herein we report for the first time the trend of improved cycling behavior of Na0/+ in N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide with 500 ppm H2O. The addition of water to this ionic liquid electrolyte promotes the breakdown of the [FSI]- anion towards beneficial SEI formation. The benefits during plating and stripping of sodium is observed as lower total polarization during symmetrical cell cycling and decreased electrode/electrolyte interface impedance. Sodium metal surfaces after cycling with 500 ppm H2O are shown to be smooth in morphology in comparison to lower additive concentrations. The outcome of adventitious moisture benefiting Na0/+ cycling in an ionic liquid, contrary to conventional electrolytes, allows flexibility in ionic liquid electrolyte design to the benefit of battery manufacturers.

Materials Challenges and Opportunities of Lithium-ion Batteries for Electrical Energy Storage

NASA Astrophysics Data System (ADS)

Manthiram, Arumugam

2011-03-01

Electrical energy storage has emerged as a topic of national and global importance with respect to establishing a cleaner environment and reducing the dependence on foreign oil. Batteries are the prime candidates for electrical energy storage. They are the most viable near-term option for vehicle applications and the efficient utilization of intermittent energy sources like solar and wind. Lithium-ion batteries are attractive for these applications as they offer much higher energy density than other rechargeable battery systems. However, the adoption of lithium-ion battery technology for vehicle and stationary storage applications is hampered by high cost, safety concerns, and limitations in energy, power, and cycle life, which are in turn linked to severe materials challenges. This presentation, after providing an overview of the current status, will focus on the physics and chemistry of new materials that can address these challenges. Specifically, it will focus on the design and development of (i) high-capacity, high-voltage layered oxide cathodes, (ii) high-voltage, high-power spinel oxide cathodes, (iii) high-capacity silicate cathodes, and (iv) nano-engineered, high-capacity alloy anodes. With high-voltage cathodes, a critical issue is the instability of the electrolyte in contact with the highly oxidized cathode surface and the formation of solid-electrolyte interfacial (SEI) layers that degrade the performance. Accordingly, surface modification of cathodes with nanostructured materials and self-surface segregation during the synthesis process to suppress SEI layer formation and enhance the energy, power, and cycle life will be emphasized. With the high-capacity alloy anodes, a critical issue is the huge volume change occurring during the charge-discharge process and the consequent poor cycle life. Dispersion of the active alloy nanoparticles in an inactive metal oxide-carbon matrix to mitigate this problem and realize long cycle life will be presented.

Web-structured graphitic carbon fiber felt as an interlayer for rechargeable lithium-sulfur batteries with highly improved cycling performance

NASA Astrophysics Data System (ADS)

Lee, Dong Kyu; Ahn, Chi Won; Jeon, Hwan-Jin

2017-08-01

Graphitic carbon fiber felt (GCFF) with a crystalline graphitic carbon structure was facilely prepared by a combination of electrospinning and graphitization (2800 °C heat treatment) and was used as an interlayer between the cathode and separator in Li-S batteries. This GCFF interlayer trapped the polysulfides on the cathode side and increased the utilization of sulfur by suppressing the shuttle phenomenon. Also, the GCFF was shown to be able to act as an upper current collector to reduce the charge-transfer resistance owing to the high crystallinity of the graphitic carbon fibers. The sulfur cathode with the GCFF interlayer showed a high specific initial discharge capacity of 1280.14 mAh g-1 and excellent cycling stability (1004.62 mAh g-1 after 100 cycles) at 0.2 C. Also, an image of the glass fiber (GF) separator on the anode side confirmed the presence of an SEI after 200 cycles, which apparently resulted from stable Li deposition on the Li metal because of the low or medium concentration of sulfur in the electrolyte solution. Our observations should contribute to elucidating the key features of complex three-dimensional carbon fabrics with crystalline graphitic structures that allow them, when inserted as interlayers, to markedly improve the performance of rechargeable batteries.

Adaptive harvest management: Adjustments for SEIS 2013

USGS Publications Warehouse

Boomer, Scott; Johnson, Fred A.; Zimmerman, Guthrie S.

2015-01-01

This report provides a summary of revised methods and assessment results based on updated adaptive harvest management (AHM) protocols developed in response to the preferred alternative specified in the Final Supplemental Environmental Impact Statement on the Issuance of Annual Regulations Permitting the Hunting of Migratory Birds (SEIS; U.S. Department of the Interior 2013). We describe necessary changes to optimization procedures and decision processes for the implementation of AHM for midcontinent, eastern and western mallards (Anas platyrhynchos), northern pintails (Anas acuta), and scaup (Aythya affinis, A. marila) decision frameworks. We present this final report for communication purposes, and acknowledge that any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Fluoroethylene Carbonate as a Directing Agent in Amorphous Silicon Anodes: Electrolyte Interface Structure Probed by Sum Frequency Vibrational Spectroscopy and Ab Initio Molecular Dynamics.

PubMed

Horowitz, Yonatan; Han, Hui-Ling; Soto, Fernando A; Ralston, Walter T; Balbuena, Perla B; Somorjai, Gabor A

2018-02-14

Fluorinated compounds are added to carbonate-based electrolyte solutions in an effort to create a stable solid electrolyte interphase (SEI). The SEI mitigates detrimental electrolyte redox reactions taking place on the anode's surface upon applying a potential in order to charge (discharge) the lithium (Li) ion battery. The need for a stable SEI is dire when the anode material is silicon as silicon cracks due to its expansion and contraction upon lithiation and delithiation (charge-discharge) cycles, consequently limiting the cyclability of a silicon-based battery. Here we show the molecular structures for ethylene carbonate (EC): fluoroethylene carbonate (FEC) solutions on silicon surfaces by sum frequency generation (SFG) vibrational spectroscopy, which yields vibrational spectra of molecules at interfaces and by ab initio molecular dynamics (AIMD) simulations at open circuit potential. Our AIMD simulations and SFG spectra indicate that both EC and FEC adsorb to the amorphous silicon (a-Si) through their carbonyl group (C═O) oxygen atom with no further desorption. We show that FEC additives induce the reorientation of EC molecules to create an ordered, up-right orientation of the electrolytes on the Si surface. We suggest that this might be helpful for Li diffusion under applied potential. Furthermore, FEC becomes the dominant species at the a-Si surface as the FEC concentration increases above 20 wt %. Our finding at open circuit potential can now initiate additive design to not only act as a sacrificial compound but also to produce a better suited SEI for the use of silicon anodes in the Li-ion vehicular industry.

Perfluoroalkyl-substituted ethylene carbonates: Novel electrolyte additives for high-voltage lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zhu, Ye; Casselman, Matthew D.; Li, Yan; Wei, Alexander; Abraham, Daniel P.

2014-01-01

A new family of polyfluoroalkyl-substituted ethylene carbonates is synthesized and tested as additives in lithium-ion cells containing EC:EMC + LiPF6-based electrolyte. The influence of these compounds is investigated in Li1.2Ni0.15Mn0.55Co0.1O2//graphite cells via a combination of galvanostatic cycling and electrochemical impedance spectroscopy (EIS) tests. Among the four additives studied in this work (4-(trifluoromethyl)-1,3-dioxolan-2-one (TFM-EC), 4-(perfluorobutyl)-1,3-dioxolan-2-one (PFB-EC), 4-(perfluorohexyl)-1,3-dioxolan-2-one (PFH-EC), and 4-(perfluorooctyl)-1,3-dioxolan-2-one (PFO-EC)), small amounts (0.5 wt%) of PFO-EC is found to be most effective in lessening cell performance degradation during extended cycling. Linear sweep voltammetry (LSV), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy are used to further characterize the effects of PFO-EC on the positive and negative electrodes. LSV data from the electrolyte, and XPS analyses of electrodes harvested after cycling, suggest that PFO-EC is oxidized on the cathode forming surface films that slow electrode/cell impedance rise. Differential capacity (dQ/dV) plots from graphite//Li cells suggest that PFO-EC is involved in solid electrolyte interphase (SEI) formation. Raman data from anodes after cycling suggest that structural disordering of graphite is reduced by the addition of PFO-EC, which may explain the improved cell capacity retention.

Issues in NASA program and project management

NASA Technical Reports Server (NTRS)

Hoban, Francis T. (Editor)

1992-01-01

This volume is the fifth in an ongoing series on aerospace project management at NASA. Articles in this volume cover: an overview of the project cycle; SE&I management for manned space flight programs; shared experiences from NASA Programs and Projects - 1975; cost control for Mariner Venus/Mercury 1973; and the Space Shuttle - a balancing of design and politics. A section on resources for NASA managers rounds out the publication.

Effects of Surface Oxygen on the Performance of Carbon as an Anode in Lithium-Ion Batteries

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh; Clark, Gregory W.

2001-01-01

Carbon materials with similar bulk structure but different surface oxygen were compared for their performance as anodes in lithium-ion battery. The bulk structure was such that the graphene planes were perpendicular to the surface. Three types of surfaces were examined: surface containing C=O type oxygen. surface containing -O-C type oxygen, and surface containing high concentration of active sites. The test involved cycles of lithium insertion into and release from the carbon materials, which was in the half cells of carbon/saturated LiI-50/50 (vol %) EC and DMC/lithium. During the first cycle of lithium insertion, the presence of adsorbed oxygen, -O-C type oxygen, active carbon sites, and C=O type oxygen resulted in the formation of solid-electrolyte interface (SEI) when the carbon's voltage relative to lithium metal was >1.35, 1 to 1.35, 0.5 to 1, and 0.67 to 0.7 V, respectively. An optimum -O-C type oxygen and a minimum C=O type oxygen was found to increase the reversible and decrease the irreversible capacity of carbon. Active sites on the carbon surface result in a large irreversible capacity and a second lithium insertion-release mechanism. However, this new mechanism has a short cycle life.

Double-plasma enhanced carbon shield for spatial/interfacial controlled electrodes in lithium ion batteries via micro-sized silicon from wafer waste

NASA Astrophysics Data System (ADS)

Chen, Bing-Hong; Chuang, Shang-I.; Duh, Jenq-Gong

2016-11-01

Using spatial and interfacial control, the micro-sized silicon waste from wafer slurry could greatly increase its retention potential as a green resource for silicon-based anode in lithium ion batteries. Through step by step spatial and interfacial control for electrode, the cyclability of recycled waste gains potential performance from its original poor retention property. In the stages of spatial control, the electrode stabilizers of active, inactive and conductive additives were mixed into slurries for maintaining architecture and conductivity of electrode. In addition, a fusion electrode modification of interfacial control combines electrolyte additive, technique of double-plasma enhanced carbon shield (D-PECS) to convert the chemical bond states and to alter the formation of solid electrolyte interphases (SEIs) in the first cycle. The depth profiles of chemical composition from external into internal electrode illustrate that the fusion electrode modification not only forms a boundary to balance the interface between internal and external electrodes but also stabilizes the SEIs formation and soothe the expansion of micro-sized electrode. Through these effect approaches, the performance of micro-sized Si waste electrode can be boosted from its serious capacity degradation to potential retention (200 cycles, 1100 mAh/g) and better meet the requirements for facile and cost-effective in industrial production.

CU’s Department of Geological Sciences - Science Education Initiative Project (GEOL-SEI): A five-year plan for introducing and supporting an evidence-based and scientific approach to teaching

NASA Astrophysics Data System (ADS)

Arthurs, L.; Budd, D. A.

2009-12-01

The Science Education Initiative (SEI) at the University of Colorado at Boulder was conceived in 2006 with the goal of improving science education at the undergraduate level by changing the basic approach to teaching in science departments. Five departments were selected on a competitive basis for participation in the SEI. The SEI is operating as a five year plan with funding of ~$1 million/year for the five departments. The goal of the SEI is to implement sustainable department-level change for an evidence-based and scientific approach to teaching. Among the five departments receiving funding for discipline-specific SEI projects is the Department of Geological Sciences (GEOL-SEI). The GEOL-SEI has worked to transform geology courses beginning with lower division large enrollment courses and moving towards upper division courses. They are transformed on the basis of existing research into how people learn, and they are characterized by the use of learning goals and effective instructional approaches. Furthermore, a natural component of the transformation towards evidence-based and scientific approaches to teaching is geocognition and geoscience education research. This research focuses on how students think about geologic concepts (e.g. misconceptions) and the effectiveness of different instructional approaches (e.g. the implementation of instructional technologies, peer learning activities, homework, and labs). The research is conducted by post-doctoral fellows (with PhDs in geology and pedagogical training) in collaboration with the instructional faculty members. The directorate of CU’s Science Education Initiative provides the fellows with training useful for conducting the research. Currently, into the 4th year of its 5-year plan, the GEOL-SEI is working towards publishing its findings and exploring options for sustaining various changes made to courses and new departmental programs that support student learning (e.g. GEOL Tutoring & Study Room).

‘Safer Environment Interventions’: A qualitative synthesis of the experiences and perceptions of people who inject drugs

PubMed Central

McNeil, Ryan; Small, Will

2014-01-01

There is growing acknowledgment that social, structural, and environmental forces produce vulnerability to health harms among people who inject drugs (PWID), and safer environment interventions (SEI) have been identified as critical to mitigating the impacts of these contextual forces on drug-related harm. To date, however, SEIs have been under-theorized in the literature, and how they minimize drug-related risks across intervention types and settings has not been adequately examined. This article presents findings from a systematic review and meta-synthesis of qualitative studies reporting PWID’s experiences with three types of SEIs (syringe exchange programmes, supervised injection facilities and peer-based harm reduction interventions) published between 1997 and 2012. This meta-synthesis seeks to develop a comprehensive understanding of SEIs informed by the experiences of PWID. Twenty-nine papers representing twenty-one unique studies that included an aggregate of more than 800 PWID were included in this meta-synthesis. This meta- synthesis found that SEIs fostered social and physical environments that mitigated drug-related harms and increased access to social and material resources. Specifically, SEIs: (1) provided refuge from street-based drug scenes; (2) enabled safer injecting by reshaping the social and environmental contexts of injection drug use; (3) mediated access to resources and health care services; and, (4) were constrained by drug prohibition and law enforcement activities. These findings indicate that it is critical to situate SEIs in relation to the lived experiences of PWID, and in particular provide broader environmental support to PWID. Given that existing drug laws limit the effectiveness of interventions, drug policy reforms are needed to enable public health, and specifically SEIs, to occupy a more prominent role in the response to injection drug use. PMID:24561777

Characterization of Staphylococcus aureus strains and evidence for the involvement of non-classical enterotoxin genes in food poisoning outbreaks.

PubMed

Ciupescu, Laurentiu-Mihai; Auvray, Frederic; Nicorescu, Isabela Madalina; Meheut, Thomas; Ciupescu, Veronica; Lardeux, Anne-Laure; Tanasuica, Rodica; Hennekinne, Jacques-Antoine

2018-06-05

To an increasing extent, molecular and genetic characterization is now used to investigate foodborne outbreaks. The aim of this study was to seek molecular links among coagulase-positive staphylococci (CPS) isolated from three recent food poisoning outbreaks in Romania using polymerase chain reaction and pulsed-field gel electrophoresis (PFGE) techniques. Nineteen CPS isolates were identified as Staphylococcus aureus by detection of the 23S rDNA gene. Among them, 15 carried at least one staphylococcal enterotoxin-encoding gene (se). The Calarași outbreak strains grouped in pulsotype 2 and were sed/sej/ser-positive, whereas the Arad outbreak strains clustered in pulsotype 17 and were either sed/seg/sei/sej/ser- or seg/sei-positive. The Pitești outbreak strains clustered in pulsotype 1 and, surprisingly, possessed only one enterotoxin gene, i.e. seh. Similar to other European countries, the seh gene has been identified with increasing frequency in Romanian outbreaks; this highlights the importance of considering the application of methods recommended for staphylococcal enterotoxin regulation in Europe.

Long-term lithium-ion battery performance improvement via ultraviolet light treatment of the graphite anode

DOE PAGES

An, Seong Jin; Li, Jianlin; Sheng, Yangping; ...

2016-01-01

Effects of ultraviolet (UV) light on dried graphite anodes were investigated in terms of the cycle life of lithium ion batteries. The time variations for the UV treatment were 0 (no treatment), 20, 40, and 60 minutes. UV-light-treated graphite anodes were assembled for cycle life tests in pouch cells with pristine Li 1.02Ni 0.50Mn 0.29Co 0.19O 2 (NMC 532) cathodes. UV treatment for 40 minutes resulted in the highest capacity retention and the lowest resistance after the cycle life testing. X-ray photoelectron spectroscopy (XPS) and contact angle measurements on the graphite anodes showed changes in surface chemistry and wetting aftermore » the UV treatment. XPS also showed increases in solvent products and decreases in salt products on the SEI surface when UV-treated anodes were used. In conclusion, the thickness of the surface films and their compositions on the anodes and cathodes were also estimated using survey scans and snapshots from XPS depth profiles.« less

Component-/structure-dependent elasticity of solid electrolyte interphase layer in Li-ion batteries: Experimental and computational studies

NASA Astrophysics Data System (ADS)

Shin, Hosop; Park, Jonghyun; Han, Sangwoo; Sastry, Ann Marie; Lu, Wei

2015-03-01

The mechanical instability of the Solid Electrolyte Interphase (SEI) layer in lithium ion (Li-ion) batteries causes significant side reactions resulting in Li-ion consumption and cell impedance rise by forming further SEI layers, which eventually leads to battery capacity fade and power fade. In this paper, the composition-/structure-dependent elasticity of the SEI layer is investigated via Atomic Force Microscopy (AFM) measurements coupled with X-ray Photoelectron Spectroscopy (XPS) analysis, and atomistic calculations. It is observed that the inner layer is stiffer than the outer layer. The measured Young's moduli are mostly in the range of 0.2-4.5 GPa, while some values above 80 GPa are also observed. This wide variation of the observed elastic modulus is elucidated by atomistic calculations with a focus on chemical and structural analysis. The numerical analysis shows the Young's moduli range from 2.4 GPa to 58.1 GPa in the order of the polymeric, organic, and amorphous inorganic components. The crystalline inorganic component (LiF) shows the highest value (135.3 GPa) among the SEI species. This quantitative observation on the elasticity of individual components of the SEI layer must be essential to analyzing the mechanical behavior of the SEI layer and to optimizing and controlling it.

Investigation of electrolytes utilized for high-voltage LiNi0.5Mn1.5O4 batteries

NASA Astrophysics Data System (ADS)

Qin, Yinping; Lin, Huan; Liu, Yang; Wang, Deyu

2017-10-01

The main challenge of high-voltage LiNi0.5Mn1.5O4 (LNMO), which is one of the most promising cathodes with the redox plateau of ˜4.75V vs Li+/Li, is the decomposition of electrolyte. In fact, our studies show that LNMO presents the good capacity retention ratio, higher than 80% after 300 cycles, in the electrolyte with the mixture of pure carbonate solvents. Even 92% of the initial capacity in the 300th cycle is remained in the optimal composition. Obviously, high-voltage LiNi0.5Mn1.5O4 can get excellent cycle performance without any special additives. In addition, we studied the electrochemical behavior of viny lene carbonate (VC) and ethylene sulfite (ES) in high potential. The results indicate that VC and ES can be electrochemically oxidized at 4.6 V and 4.05 V vs Li+/Li, respectively. In the cells with the electrolytes containing VC and ES respectively, the discharge capacities are significantly diminished. Also, the thick and high-resistance sediment layers are formed on the surface of LNMO. We concluded that the SEI-forming additives widely used in commercial batteries may firstly decompose on cathode side. Therefore, the electrolyte systems should be redesigned for graphite-LNMO batteries.

Fundamental Investigation of Si Anode in Li-Ion Cells

NASA Technical Reports Server (NTRS)

Wu, James J.; Bennett, William R.

2012-01-01

Silicon is a promising and attractive anode material to replace graphite for high capacity lithium ion cells since its theoretical capacity is approximately 10 times of graphite and it is an abundant element on earth. However, there are challenges associated with using silicon as Li-ion anode due to the significant first cycle irreversible capacity loss and subsequent rapid capacity fade during cycling. In this paper, cyclic voltammetry and electrochemical impedance spectroscopy are used to build a fundamental understanding of silicon anodes. The results show that it is difficult to form the SEI film on the surface of Si anode during the first cycle, the lithium ion insertion and de-insertion kinetics for Si are sluggish, and the cell internal resistance changes with the state of lithiation after electrochemical cycling. These results are compared with those for extensively studied graphite anodes. The understanding gained from this study will help to design better Si anodes.

Science & Engineering Indicators 2016. National Science Board

ERIC Educational Resources Information Center

National Science Foundation, 2016

2016-01-01

"Science and Engineering Indicators" (SEI) is first and foremost a volume of record comprising high-quality quantitative data on the U.S. and international science and engineering enterprise. SEI includes an overview and seven chapters that follow a generally consistent pattern. The chapter titles are as follows: (1) Elementary and…

Structured English Immersion: A Step-by-Step Guide for K-6 Teachers and Administrators.

ERIC Educational Resources Information Center

Haver, Johanna J.

This book describes Structured English Immersion (SEI) for English language learners (ELLs). Seven chapters focus on the following: (1) "Identification, Assessment, and Placement" (e.g., California's school districts implement SEI and proper placement of students); (2) "Listening Skills" (e.g., time on task, total physical…

78 FR 63069 - Special Regulations; Areas of the National Park System; Yellowstone National Park; Winter Use

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-23

... soundscapes, visitor use and experience, and park operations. Impacts associated with each of the alternatives..., soundscapes, and health and safety, were used in formulating the alternatives in the Plan/SEIS. Applies the... To mitigate impacts to wildlife, air quality, natural soundscapes, and visitor and employee safety...

CMMI (registered trademark) for Services, Version 1.2

DTIC Science & Technology

2009-02-01

background in information technology, especially those familiar with disciplines like service - oriented architecture (SOA) or software as a service ( SaaS ). In... services , the Software Engineering Institute (SEI) has found several dimensions that an organization can focus on to improve its business. Figure...International Business Machines) and the SEI [Humphrey 1989]. Humphrey’s book, Managing the Software Process, provides a CMMI for Services Version 1.2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strelcov, Evgheni; Cothren, Joshua E.; Leonard, Donovan N.

Progress in rational engineering of Li-ion batteries requires better understanding of the electrochemical processes and accompanying transformations in the electrode materials on multiple length scales. In spite of recent progress in utilizing transmission electron microscopy (TEM) to analyze these materials, in situ scanning electron microscopy (SEM) was mostly overlooked as a powerful tool that allows probing these phenomena on the nano and mesoscale. In this paper, we report on in situ SEM study of lithiation in a V 2O 5-based single-nanobelt battery with ionic liquid electrolyte. Coupled with cyclic voltammetry measurements, in situ SEM revealed the peculiarities of subsurface intercalation,more » formation of solid-electrolyte interface (SEI) and electromigration of liquid. We observed that single-crystalline vanadia nanobelts do not undergo large-scale amorphization or fracture during electrochemical cycling, but rather transform topochemically with only a slight shape distortion. Lastly, the SEI layer seems to have significant influence on the lithium ion diffusion and overall capacity of the single-nanobelt battery.« less

In Situ Potentiodynamic Analysis of the Electrolyte/Silicon Electrodes Interface Reactions - A Sum Frequency Generation Vibrational Spectroscopy Study

DOE PAGES

Horowitz, Yonatan; Han, Hui-Ling; Ross, Philip N.; ...

2015-12-11

The key factor in long-term use of batteries is the formation of an electrically insulating solid layer that allows lithium ion transport but stops further electrolyte redox reactions on the electrode surface, hence solid electrolyte interphase (SEI). In this paper, we have studied a common electrolyte, 1.0 M LiPF 6/ethylene carbonate (EC)/diethyl carbonate (DEC), reduction products on crystalline silicon (Si) electrodes in a lithium (Li) half-cell system under reaction conditions. We employed in situ sum frequency generation vibrational spectroscopy (SFG-VS) with interface sensitivity in order to probe the molecular composition of the SEI surface species under various applied potentials wheremore » electrolyte reduction is expected. We found that, with a Si(100)-hydrogen terminated wafer, a Si-ethoxy (Si-OC 2H 5) surface intermediate forms due to DEC decomposition. Our results suggest that the SEI surface composition varies depending on the termination of Si surface, i.e., the acidity of the Si surface. We provide the evidence of specific chemical composition of the SEI on the anode surface under reaction conditions. This supports an electrochemical electrolyte reduction mechanism in which the reduction of the DEC molecule to an ethoxy moiety plays a key role. Finally, these findings shed new light on the formation mechanism of SEI on Si anodes in particular and on SEI formation in general.« less

Depression in College Students: Student Experience Inventory.

ERIC Educational Resources Information Center

Kirkland, Angela G.; Redfield, Doris L.

To assess depression in college students, two inventories were compared: the Student Experience Inventory (SEI) and the Beck Depression Inventory (BDI). SEI, a self-report questionnaire, contains 56 items that are designed to measure hopelessness and decreased energy levels, as well as five factors covered in BDI: (1) negative affect toward self,…

Designer interphases for the lithium-oxygen electrochemical cell

PubMed Central

Choudhury, Snehashis; Wan, Charles Tai-Chieh; Al Sadat, Wajdi I.; Tu, Zhengyuan; Lau, Sampson; Zachman, Michael J.; Kourkoutis, Lena F.; Archer, Lynden A.

2017-01-01

An electrochemical cell based on the reversible oxygen reduction reaction: 2Li+ + 2e− + O2 ↔ Li2O2, provides among the most energy dense platforms for portable electrical energy storage. Such Lithium-Oxygen (Li-O2) cells offer specific energies competitive with fossil fuels and are considered promising for electrified transportation. Multiple, fundamental challenges with the cathode, anode, and electrolyte have limited practical interest in Li-O2 cells because these problems lead to as many practical shortcomings, including poor rechargeability, high overpotentials, and specific energies well below theoretical expectations. We create and study in-situ formation of solid-electrolyte interphases (SEIs) based on bromide ionomers tethered to a Li anode that take advantage of three powerful processes for overcoming the most stubborn of these challenges. The ionomer SEIs are shown to protect the Li anode against parasitic reactions and also stabilize Li electrodeposition during cell recharge. Bromine species liberated during the anchoring reaction also function as redox mediators at the cathode, reducing the charge overpotential. Finally, the ionomer SEI forms a stable interphase with Li, which protects the metal in high Gutmann donor number liquid electrolytes. Such electrolytes have been reported to exhibit rare stability against nucleophilic attack by Li2O2 and other cathode reaction intermediates, but also react spontaneously with Li metal anodes. We conclude that rationally designed SEIs able to regulate transport of matter and ions at the electrolyte/anode interface provide a promising platform for addressing three major technical barriers to practical Li-O2 cells. PMID:28439557

Focus on Resiliency: A Process-Oriented Approach to Security

DTIC Science & Technology

2005-11-01

by ANSI Std Z39-18 © 2005 Carnegie Mellon University CSI v1.0 2 Agenda About the SEI Characterizing the problem Security, resiliency, and risk A...2005 Carnegie Mellon University CSI v1.0 5 SEI Technical Programs Product Line Systems Dynamic Systems Software Engineering Process Management...University CSI v1.0 7 What is the problem? Is your organization’s security capability sufficient to identify and manage risks that result from failed

Enabling electrolyte compositions for columnar silicon anodes in high energy secondary batteries

NASA Astrophysics Data System (ADS)

Piwko, Markus; Thieme, Sören; Weller, Christine; Althues, Holger; Kaskel, Stefan

2017-09-01

Columnar silicon structures are proven as high performance anodes for high energy batteries paired with low (sulfur) or high (nickel-cobalt-aluminum oxide, NCA) voltage cathodes. The introduction of a fluorinated ether/sulfolane solvent mixture drastically improves the capacity retention for both battery types due to an improved solid electrolyte interface (SEI) on the surface of the silicon electrode which reduces irreversible reactions normally causing lithium loss and rapid capacity fading. For the lithium silicide/sulfur battery cycling stability is significantly improved as compared to a frequently used reference electrolyte (DME/DOL) reaching a constant coulombic efficiency (CE) as high as 98%. For the silicon/NCA battery with higher voltage, the addition of only small amounts of fluoroethylene carbonate (FEC) to the novel electrolyte leads to a stable capacity over at least 50 cycles and a CE as high as 99.9%. A high volumetric energy density close to 1000 Wh l-1 was achieved with the new electrolyte taking all inactive components of the stack into account for the estimation.

Integration of the tricarboxylic acid (TCA) cycle with cAMP signaling and Sfl2 pathways in the regulation of CO2 sensing and hyphal development in Candida albicans

PubMed Central

Tao, Li; Zhang, Yulong; Fan, Shuru; Nobile, Clarissa J.; Guan, Guobo; Huang, Guanghua

2017-01-01

Morphological transitions and metabolic regulation are critical for the human fungal pathogen Candida albicans to adapt to the changing host environment. In this study, we generated a library of central metabolic pathway mutants in the tricarboxylic acid (TCA) cycle, and investigated the functional consequences of these gene deletions on C. albicans biology. Inactivation of the TCA cycle impairs the ability of C. albicans to utilize non-fermentable carbon sources and dramatically attenuates cell growth rates under several culture conditions. By integrating the Ras1-cAMP signaling pathway and the heat shock factor-type transcription regulator Sfl2, we found that the TCA cycle plays fundamental roles in the regulation of CO2 sensing and hyphal development. The TCA cycle and cAMP signaling pathways coordinately regulate hyphal growth through the molecular linkers ATP and CO2. Inactivation of the TCA cycle leads to lowered intracellular ATP and cAMP levels and thus affects the activation of the Ras1-regulated cAMP signaling pathway. In turn, the Ras1-cAMP signaling pathway controls the TCA cycle through both Efg1- and Sfl2-mediated transcriptional regulation in response to elevated CO2 levels. The protein kinase A (PKA) catalytic subunit Tpk1, but not Tpk2, may play a major role in this regulation. Sfl2 specifically binds to several TCA cycle and hypha-associated genes under high CO2 conditions. Global transcriptional profiling experiments indicate that Sfl2 is indeed required for the gene expression changes occurring in response to these elevated CO2 levels. Our study reveals the regulatory role of the TCA cycle in CO2 sensing and hyphal development and establishes a novel link between the TCA cycle and Ras1-cAMP signaling pathways. PMID:28787458

The Education of English Language Learners in Arizona: A History of Underachievement

ERIC Educational Resources Information Center

Garcia, Eugene E.; Lawton, Kerry; Diniz De Figueriedo, Eduardo H.

2012-01-01

Background: The state of Arizona has recently mandated the Structured English Immersion Model (SEI) in the state's public schools, and as a result the local flexibility that existed regarding the choice of program models for ELLs has ended. In the school year 2008-09, these regulations were made even more restrictive after the implementation of…

The cell cycle of early mammalian embryos: lessons from genetic mouse models.

PubMed

Artus, Jérôme; Babinet, Charles; Cohen-Tannoudji, Michel

2006-03-01

Genes coding for cell cycle components predicted to be essential for its regulation have been shown to be dispensable in mice, at the whole organism level. Such studies have highlighted the extraordinary plasticity of the embryonic cell cycle and suggest that many aspects of in vivo cell cycle regulation remain to be discovered. Here, we discuss the particularities of the mouse early embryonic cell cycle and review the mutations that result in cell cycle defects during mouse early embryogenesis, including deficiencies for genes of the cyclin family (cyclin A2 and B1), genes involved in cell cycle checkpoints (Mad2, Bub3, Chk1, Atr), genes involved in ubiquitin and ubiquitin-like pathways (Uba3, Ubc9, Cul1, Cul3, Apc2, Apc10, Csn2) as well as genes the function of which had not been previously ascribed to cell cycle regulation (Cdc2P1, E4F and Omcg1).

75 FR 18572 - Supplemental Environmental Impact Statement for Sequoyah Nuclear Plant Units 1 and 2 License...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-12

... the carbon emissions of its generating system and take advantage of lower carbon dioxide-emitting.... The SEIS will include examination of a range of supply-side and demand- side management options for... both the scope of alternatives and environmental issues that should be addressed as part of the SEIS...

Coordination of Myeloid Differentiation with Reduced Cell Cycle Progression by PU.1 Induction of MicroRNAs Targeting Cell Cycle Regulators and Lipid Anabolism.

PubMed

Solomon, Lauren A; Podder, Shreya; He, Jessica; Jackson-Chornenki, Nicholas L; Gibson, Kristen; Ziliotto, Rachel G; Rhee, Jess; DeKoter, Rodney P

2017-05-15

During macrophage development, myeloid progenitor cells undergo terminal differentiation coordinated with reduced cell cycle progression. Differentiation of macrophages from myeloid progenitors is accompanied by increased expression of the E26 transformation-specific transcription factor PU.1. Reduced PU.1 expression leads to increased proliferation and impaired differentiation of myeloid progenitor cells. It is not understood how PU.1 coordinates macrophage differentiation with reduced cell cycle progression. In this study, we utilized cultured PU.1-inducible myeloid cells to perform genome-wide chromatin immunoprecipitation sequencing (ChIP-seq) analysis coupled with gene expression analysis to determine targets of PU.1 that may be involved in regulating cell cycle progression. We found that genes encoding cell cycle regulators and enzymes involved in lipid anabolism were directly and inducibly bound by PU.1 although their steady-state mRNA transcript levels were reduced. Inhibition of lipid anabolism was sufficient to reduce cell cycle progression in these cells. Induction of PU.1 reduced expression of E2f1 , an important activator of genes involved in cell cycle and lipid anabolism, indirectly through microRNA 223. Next-generation sequencing identified microRNAs validated as targeting cell cycle and lipid anabolism for downregulation. These results suggest that PU.1 coordinates cell cycle progression with differentiation through induction of microRNAs targeting cell cycle regulators and lipid anabolism. Copyright © 2017 American Society for Microbiology.

Anion-Dependent Potential Precycling Effects on Lithium Deposition/Dissolution Reaction Studied by an Electrochemical Quartz Crystal Microbalance.

PubMed

Smaran, Kumar Sai; Shibata, Sae; Omachi, Asami; Ohama, Ayano; Tomizawa, Eika; Kondo, Toshihiro

2017-10-19

The electrochemical quartz crystal microbalance technique was employed to study the initial stage of the electrodeposition and dissolution of lithium utilizing three kinds of electrolyte solutions such as LiPF 6 , LiTFSI, or LiFSI in tetraglyme. The native-SEI (solid-electrolyte interphase) formed by a potential prescan before lithium deposition/dissolution in all three solutions. Simultaneous additional SEI (add-SEI) deposition and its dissolution with lithium deposition and dissolution, respectively, were observed in LiPF 6 and LiTFSI. Conversely, the add-SEI dissolution with lithium deposition and its deposition with lithium dissolution were observed in LiFSI. Additional potential precycling resulted in the accumulation of a "pre-SEI" layer over the native-SEI layer in all of the solutions. With the pre-SEI, only lithium deposition/dissolution were significantly observed in LiTFSI and LiFSI. On the basis of the potential dependences of the mass and resistance changes, the anion-dependent effects of such a pre-SEI layer presence/absence on the lithium deposition/dissolution processes were discussed.

Proceedings of the Fourth International Workshop on a Research Agenda for Maintenance and Evolution of Service-Oriented Systems (MESOA 2010)

DTIC Science & Technology

2011-09-01

service -oriented systems • Software -as-a- Service ( SaaS ) • social network infrastructures • Internet marketing • mobile computing • context awareness...Maintenance and Evolution of Service -Oriented Systems (MESOA 2010), organized by members of the Carnegie Mellon Software Engineering Institute’s...CMU/SEI-2011-SR-008 | 1 1 Workshop Introduction The Software Engineering Institute (SEI) started developing a service -oriented architecture

Diet misreporting can be corrected: confirmation of the association between energy intake and fat-free mass in adolescents.

PubMed

Vainik, Uku; Konstabel, Kenn; Lätt, Evelin; Mäestu, Jarek; Purge, Priit; Jürimäe, Jaak

2016-10-01

Subjective energy intake (sEI) is often misreported, providing unreliable estimates of energy consumed. Therefore, relating sEI data to health outcomes is difficult. Recently, Börnhorst et al. compared various methods to correct sEI-based energy intake estimates. They criticised approaches that categorise participants as under-reporters, plausible reporters and over-reporters based on the sEI:total energy expenditure (TEE) ratio, and thereafter use these categories as statistical covariates or exclusion criteria. Instead, they recommended using external predictors of sEI misreporting as statistical covariates. We sought to confirm and extend these findings. Using a sample of 190 adolescent boys (mean age=14), we demonstrated that dual-energy X-ray absorptiometry-measured fat-free mass is strongly associated with objective energy intake data (onsite weighted breakfast), but the association with sEI (previous 3-d dietary interview) is weak. Comparing sEI with TEE revealed that sEI was mostly under-reported (74 %). Interestingly, statistically controlling for dietary reporting groups or restricting samples to plausible reporters created a stronger-than-expected association between fat-free mass and sEI. However, the association was an artifact caused by selection bias - that is, data re-sampling and simulations showed that these methods overestimated the effect size because fat-free mass was related to sEI both directly and indirectly via TEE. A more realistic association between sEI and fat-free mass was obtained when the model included common predictors of misreporting (e.g. BMI, restraint). To conclude, restricting sEI data only to plausible reporters can cause selection bias and inflated associations in later analyses. Therefore, we further support statistically correcting sEI data in nutritional analyses. The script for running simulations is provided.

BlueSeis3A - performance, laboratory tests and applications

NASA Astrophysics Data System (ADS)

Bernauer, F.; Wassermann, J. M.; de Toldi, E.; Guattari, F.; Ponceau, D.; Ripepe, M.; Igel, H.

2017-12-01

One of the most emerging developments in seismic instrumentation is the application of fiber optic gyroscopes as portable rotational ground motion sensors. In the framework of the European Research Council Project, ROMY (ROtational Motions in seismologY), BlueSeis3A was developed in a collaboration between researchers from Ludwig-Maximilians University of Munich, Germany, and the fiber optic sensors manufacturer iXblue, France. With its high sensitivity (20 nrads-1Hz-1/2) in a broad frequency range (0.001 Hz to 50 Hz) BlueSeis3A opens a variety of applications which were up to now hampered by the lack of such an instrument. In this contribution, we will first present performance characteristics of BlueSeis3A with a focus on timing stability and scale factor linearity. In a second part we demonstrate the benefit of directly measured rotational motion for dynamic tilt correction of measurements made with a classical seismometer. A well known tilt signal was produced with a shake table and recorded simultaneously with a classical seismometer and BlueSeis3A. The seismometer measurement could be improved significantly by subtracting the coherent tilt signal which was measured directly with the rotational motion sensor. As a last part we show the advantage of directly measured rotational motion for applications in civil engineering. Results from a measurement campaign in the Giotto bell tower in the city of Florence, Italy, show the possibility of direct observation of torsional modes by deploying a rotational motion sensor inside the structure.

Glassy Metal Alloy Nanofiber Anodes Employing Graphene Wrapping Layer: Toward Ultralong-Cycle-Life Lithium-Ion Batteries.

PubMed

Jung, Ji-Won; Ryu, Won-Hee; Shin, Jungwoo; Park, Kyusung; Kim, Il-Doo

2015-07-28

Amorphous silicon (a-Si) has been intensively explored as one of the most attractive candidates for high-capacity and long-cycle-life anode in Li-ion batteries (LIBs) primarily because of its reduced volume expansion characteristic (∼280%) compared to crystalline Si anodes (∼400%) after full Li(+) insertion. Here, we report one-dimensional (1-D) electrospun Si-based metallic glass alloy nanofibers (NFs) with an optimized composition of Si60Sn12Ce18Fe5Al3Ti2. On the basis of careful compositional tailoring of Si alloy NFs, we found that Ce plays the most important role as a glass former in the formation of the metallic glass alloy. Moreover, Si-based metallic glass alloy NFs were wrapped by reduced graphene oxide sheets (specifically Si60Sn12Ce18Fe5Al3Ti2 NFs@rGO), which can prevent the direct exposure of a-Si alloy NFs to the liquid electrolyte and stabilize the solid-electrolyte interphase (SEI) layers on the surfaces of rGO sheets while facilitating electron transport. The metallic glass nanofibers exhibited superior electrochemical cell performance as an anode: (i) Si60Sn12Ce18Fe5Al3Ti2 NFs show a high specific capacity of 1017 mAh g(-1) up to 400 cycles at 0.05C with negligible capacity loss as well as superior cycling performance (nearly 99.9% capacity retention even after 2000 cycles at 0.5C); (ii) Si60Sn12Ce18Fe5Al3Ti2 NFs@rGO reveals outstanding rate behavior (569.77 mAh g(-1) after 2000 cycles at 0.5C and a reversible capacity of around 370 mAh g(-1) at 4C). We demonstrate the potential suitability of multicomponent a-Si alloy NFs as a long-cycling anode material.

Enhanced charging capability of lithium metal batteries based on lithium bis(trifluoromethanesulfonyl)imide-lithium bis(oxalato)borate dual-salt electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiang, Hongfa; Shi, Pengcheng; Bhattacharya, Priyanka

2016-06-01

Rechargeable lithium (Li) metal batteries with conventional LiPF6-carbonate electrolytes have been reported to fail quickly at charging current densities of about 1.0 mA cm-2 and above. In this work, we demonstrate the rapid charging capability of the Li||LiNi0.8Co0.15Al0.05O2 (NCA) cells enabled by a dual-salt electrolyte of LiTFSI-LiBOB in a carbonate solvent mixture. It is found that the thickness of solid electrolyte interphase (SEI) layer on Li metal anode largely increases with increasing charging current density. However, the cells using the LiTFSI-LiBOB dual-salt electrolyte significantly outperforms those using the LiPF6 electrolyte at high charging current densities. At the charging current densitymore » of 1.50 mA cm-2, the Li||NCA cells with the dual-salt electrolyte can still deliver a discharge capacity of 131 mAh g-1 and a capacity retention of 80% after 100 cycles, while those with the LiPF6 electrolyte start to show fast capacity fading after the 30th cycle and only exhibit a low capacity of 25 mAh g-1 and a low retention of 15% after 100 cycles. The reasons for the good chargeability and cycling stability of the cells using LiTFSI-LiBOB dual-salt electrolyte can be attributed to the good film-formation ability of the electrolyte on lithium metal anode and the highly conductive nature of the sulfur-rich interphase layer.« less

Sinorhizobium meliloti CtrA Stability Is Regulated in a CbrA-Dependent Manner That Is Influenced by CpdR1

PubMed Central

Schallies, Karla B.; Sadowski, Craig; Meng, Julia; Chien, Peter

2015-01-01

ABSTRACT CbrA is a DivJ/PleC-like histidine kinase of DivK that is required for cell cycle progression and symbiosis in the alphaproteobacterium Sinorhizobium meliloti. Loss of cbrA results in increased levels of CtrA as well as its phosphorylation. While many of the known Caulobacter crescentus regulators of CtrA phosphorylation and proteolysis are phylogenetically conserved within S. meliloti, the latter lacks the PopA regulator that is required for CtrA degradation in C. crescentus. In order to investigate whether CtrA proteolysis occurs in S. meliloti, CtrA stability was assessed. During exponential growth, CtrA is unstable and therefore likely to be degraded in a cell cycle-regulated manner. Loss of cbrA significantly increases CtrA stability, but this phenotype is restored to that of the wild type by constitutive ectopic expression of a CpdR1 variant that cannot be phosphorylated (CpdR1D53A). Addition of CpdR1D53A fully suppresses cbrA mutant cell cycle defects, consistent with regulation of CtrA stability playing a key role in mediating proper cell cycle progression in S. meliloti. Importantly, the cbrA mutant symbiosis defect is also suppressed in the presence of CpdR1D53A. Thus, regulation of CtrA stability by CbrA and CpdR1 is associated with free-living cell cycle outcomes and symbiosis. IMPORTANCE The cell cycle is a fundamental process required for bacterial growth, reproduction, and developmental differentiation. Our objective is to understand how a two-component signal transduction network directs cell cycle events during free-living growth and host colonization. The Sinorhizobium meliloti nitrogen-fixing symbiosis with plants is associated with novel cell cycle events. This study identifies a link between the regulated stability of an essential response regulator, free-living cell cycle progression, and symbiosis. PMID:25897034

AlF 3 Surface-Coated Li[Li 0.2 Ni 0.17 Co 0.07 Mn 0.56 ]O 2 Nanoparticles with Superior Electrochemical Performance for Lithium-Ion Batteries

DOE PAGES

Sun, Shuwei; Yin, Yanfeng; Wan, Ning; ...

2015-06-24

For Li-rich layered cathode materials considerable attention has been paid owing to their high capacity performance for Li-ion batteries (LIBs). In our work, layered Li-rich Li[Li 0.2Ni 0.17Co 0.07Mn 0.56]O 2 nanoparticles are surface-modified with AlF 3 through a facile chemical deposition method. The AlF 3 surface layers have little impact on the structure of the material and act as buffers to prevent the direct contact of the electrode with the electrolyte; thus, they enhance the electrochemical performance significantly. The 3 wt% AlF 3-coated Li-rich electrode exhibits the best cycling capability and has a considerably enhanced capacity retention of 83.1%more » after 50 cycles. Moreover, the rate performance and thermal stability of the 3 wt% AlF3-coated electrode are also clearly improved. Finally, surface analysis indicates that the AlF 3 coating layer can largely suppress the undesirable growth of solid electrolyte interphase (SEI) film and, therefore, stabilizes the structure upon cycling.« less

Third SEI Technical Interchange: Proceedings

NASA Technical Reports Server (NTRS)

1992-01-01

Given here are the proceedings of the 3rd Space Exploration Initiative (SEI) Technical Interchange. Topics covered include the First Lunar Outpost (FLO), the Lunar Resource Mapper, lunar rovers, lunar habitat concepts, lunar shelter construction analysis, thermoelectric nuclear power systems for SEI, cryogenic storage, a space network for lunar communications, the moon as a solar power satellite, and off-the-shelf avionics for future SEI missions.

75 FR 39916 - Endangered and Threatened Species; Notice of Intent to Prepare a Recovery Plan for the Sei Whale

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-13

... Fisheries Service (NMFS) is announcing its intent to prepare a recovery plan for the Sei Whale (Balaenoptera... the fax comments as ``Sei Whale Recovery Plan Information'' 3. Mail: National Marine Fisheries Service... and Threatened Species; Notice of Intent to Prepare a Recovery Plan for the Sei Whale AGENCY: National...

The fast filling of nano-SnO2 in CNTs by vacuum absorption: a new approach to realize cyclic durable anodes for lithium ion batteries.

PubMed

Hu, Renzong; Sun, Wei; Liu, Hui; Zeng, Meiqin; Zhu, Min

2013-12-07

CNTs filled with amorphous-nanocrystalline SnO2, as a unique SnO2-based nanocomposite structure, were synthesized by a rapid vacuum absorption followed by calcination. The SnO2/CNT nanocomposite anodes had a much higher Li storage capacity than the pristine CNTs, as well as a markedly improved cyclic performance (430 mA h g(-1) after 300 cycles at 0.1 A g(-1)). These superior electrode properties resulted from the unique feature of the amorphous-nanocrystalline mixture of tin oxides stored in the CNT tubes of this nanocomposite, because this structure accommodated the stress and confined the volume change of Li(+) insertion/desertion in Sn. Although the nanocomposites had a large initial irreversible capacity loss due to SEI formation, it could be dramatically reduced by prelithiation treatment of the nanocomposite electrode.

Five years of specialised early intervention versus two years of specialised early intervention followed by three years of standard treatment for patients with a first episode psychosis: randomised, superiority, parallel group trial in Denmark (OPUS II).

PubMed

Albert, Nikolai; Melau, Marianne; Jensen, Heidi; Emborg, Charlotte; Jepsen, Jens Richardt Mollegaard; Fagerlund, Birgitte; Gluud, Christian; Mors, Ole; Hjorthøj, Carsten; Nordentoft, Merete

2017-01-12

To compare the effects of five years of specialised early intervention (SEI) treatment for first episode schizophrenia spectrum disorder with the standard two years of SEI plus three years of treatment as usual. Randomised, superiority, parallel group trial with blinded outcome assessment. Randomisation was centralised and computerised with concealed randomisation sequence carried out at an external site. Participants were recruited from six OPUS teams in Denmark between 2009 and 2012. OPUS teams provide SEI treatment to all patients diagnosed with a schizophrenia spectrum disorder in Denmark. 400 participants (51% women) with a mean age of 25.6 (standard deviation 4.3) were randomised to five years of SEI (experimental intervention; n=197) or to two years of SEI plus three years of treatment as usual (control; n=203). OPUS treatment consists of three core elements-modified assertive community treatment, family involvement, and social skill training-with a patient-case manager ratio of no more than 12:1. For participants randomised to five years of OPUS treatment, the treatment was largely unchanged. Participants randomised to the control group were mostly referred to community health centres after two years of SEI treatment. Follow-up assessments were conducted five years after start of OPUS treatment. Primary outcome was negative symptoms measured on the scale for assessment of negative symptoms (avolition-apathy, anhedonia, alogia, and affective blunting). Secondary outcomes were remission of both negative and psychotic symptoms, psychotic symptoms, suicidal ideation, substance abuse, compliance with medical treatment, adherence with treatment, client satisfaction, days in hospital care, and labour market affiliation. Levels of negative symptoms did not differ between the intervention group and control group (1.72 v 1.81 points; estimated mean difference -0.10 (95% confidence interval -0.33 to 0.13), P=0.39). Participants receiving five years of OPUS treatment were more likely to remain in contact with specialised mental health services (90.4% v 55.6%, P<0.001), had higher client satisfaction (estimated mean difference 2.57 points (95% confidence interval 1.36 to 3.79), P<0.001), and had a stronger working alliance (estimated mean difference 5.56 points (95% confidence interval 2.30 to 8.82), P=0.001) than the control group. This trial tests SEI treatment for up to five years for patients with first episode schizophrenia spectrum disorder; previous trials have found treatment effects for programmes lasting from one to three years. The prolonged SEI treatment had few effects, which could be due to the high level of treatment provided to control participants and the late start of specialised treatment.Trial registration Clinicaltrial.gov NCT00914238. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Rational design of Fe3O4@C yolk-shell nanorods constituting a stable anode for high-performance Li/Na-ion batteries.

PubMed

Wang, Beibei; Zhang, Xing; Liu, Xiaojie; Wang, Gang; Wang, Hui; Bai, Jintao

2018-05-24

In the current research project, we have prepared a novel Fe 3 O 4 @mesoporous carbon nanorod (denoted as Fe 3 O 4 @C) anode with yolk-shell structure for Li/Na-ion batteries via one-pot and surfactant-free synthesis strategy. The yolk-shell structure consists of Fe 3 O 4 nanorod yolk completely protected by a well-conductive mesoporous carbon shell. The substantial void space in the Fe 3 O 4 @C yolk-shell nanorod can not only accommodate the full volume expansion of inner Fe 3 O 4 nanorod, but also preserve the structural integrity of the Fe 3 O 4 @C anode and develop a stable SEI film on the outside mesoporous carbon shell during the repeated Li + /Na + insertion/extraction processes. As for lithium storage, the Fe 3 O 4 @C electrode exhibits a high specific capacity (1247 mAh g -1 ), stable cycling performance (a specific capacity of 954 mAh g -1 after 200 cycles at a current density of 0.5 A g -1 ) and excellent rate capability (specific capabilities of 1122, 958, 783, 577, and 374 mAh g -1 at 0.5, 1, 2, 4, and 8 A g -1 , respectively). As for sodium storage, the Fe 3 O 4 @C yolk-shell nanorods also maintain a reversible capacity of approximate 424 mAh g -1 at 0.1 A g -1 after 100 cycles. Copyright © 2018. Published by Elsevier Inc.

Caramel popcorn shaped silicon particle with carbon coating as a high performance anode material for Li-ion batteries.

PubMed

He, Meinan; Sa, Qina; Liu, Gao; Wang, Yan

2013-11-13

Silicon is a very promising anode material for lithium ion batteries. It has a 4200 mAh/g theoretical capacity, which is ten times higher than that of commercial graphite anodes. However, when lithium ions diffuse to Si anodes, the volume of Si will expand to almost 400% of its initial size and lead to the crack of Si. Such a huge volume change and crack cause significant capacity loss. Meanwhile, with the crack of Si particles, the conductivity between the electrode and the current collector drops. Moreover, the solid electrolyte interphase (SEI), which is generated during the cycling, reduces the discharge capacity. These issues must be addressed for widespread application of this material. In this work, caramel popcorn shaped porous silicon particles with carbon coating are fabricated by a set of simple chemical methods as active anode material. Si particles are etched to form a porous structure. The pores in Si provide space for the volume expansion and liquid electrolyte diffusion. A layer of amorphous carbon is formed inside the pores, which gives an excellent isolation between the Si particle and electrolyte, so that the formation of the SEI layer is stabilized. Meanwhile, this novel structure enhances the mechanical properties of the Si particles, and the crack phenomenon caused by the volume change is significantly restrained. Therefore, an excellent cycle life under a high rate for the novel Si electrode is achieved.

SEPG Europe 2012 Conference Proceedings

DTIC Science & Technology

2012-09-01

Process Management http://www.sei.cmu.edu SEI markings v3.2/ DM-0000022 / 30 August 2011 Copyright 2012 Carnegie Mellon University This material...Change Management Decisions in Large Enterprise Transformation Programs 18 3.1 Abstract 18 3.2 Introduction 18 3.3 Barriers for Transformation 18...Case Study #3: Enterprise Transformation Through Enterprise Data Management (Investment and Asset Management ) 25 3.7 Conclusions and Recommendations 27

Transitioning Domain Analysis: An Industry Experience.

DTIC Science & Technology

1996-06-01

References 6 Implementation 6.1 Analysis of Operator Services’ Requirements Process 21 6.2 Preliminary Planning for FODA Training by SEI 21...an academic and industry partnership took feature oriented domain analysis ( FODA ) from a methodology that is still being defined to a well-documented...to pilot the use of the Software Engineering Institute (SEI) domain analysis methodology known as feature-oriented domain analysis ( FODA ). Supported

Identification of a candidate oncogene SEI-1 within a minimal amplified region at 19q13.1 in ovarian cancer cell lines.

PubMed

Tang, Terence C-M; Sham, Jonathan S T; Xie, Dan; Fang, Yan; Huo, Ke-Ke; Wu, Qiu-Liang; Guan, Xin-Yuan

2002-12-15

High-level amplification of DNA sequence at 19q13.1 is one of the frequent genetic alterations in ovarian cancer. In an attempt to verify the minimal amplified region (MAR) at 19q13.1 and to identify the target oncogenes, 49 probes within a region from D19S425 to D19S907 ( approximately 19.5 cM) were used to survey the amplification status in four ovarian cancer cell lines that have been confirmed as containing amplification at 19q13.1. Two separated overlapping MARs, MAR1 (approximately 200 kb) and MAR2 (approximately 1.1 Mb), were identified at 19q13.1. Two candidate oncogenes, AKT2 and SEI-1, were identified in MAR2. Amplification and overexpression of these two genes in four ovarian cancer cell lines were confirmed by Southern and Northern blot analyses. The proliferation-related function of AKT2 and SEI-1 suggests that both genes are likely to be biological targets of an amplification event at 19q13.1 in ovarian cancer and to play important roles in ovarian tumorigenesis.

Mitigation of the irreversible capacity and electrolyte decomposition in a LiNi 0.5Mn 1.5O 4/nano-TiO 2 Li-ion battery

NASA Astrophysics Data System (ADS)

Brutti, Sergio; Gentili, Valentina; Reale, Priscilla; Carbone, Lorenzo; Panero, Stefania

Nanosized titanium oxides can achieve large reversible specific capacity (above 200 mAh g -1) and good rate capabilities, but suffer irreversible capacity losses in the first cycle. Moreover, due to the intrinsic safe operating potential (1.5 V), the use of titanium oxide requires to couple it with high-potential cathodes, such as lithium nickel manganese spinel (LNMO) in order to increase the energy density of the final cell. However the use of the 4.7 V vs. Li +/Li 0 LNMO cathode material requires to tackle the continuous electrolyte decomposition upon cycling. Coupling these two electrodes to make a lithium ion battery is thus highly appealing but also highly difficult because the cell balancing must account not only for the charge reversibly exchanged by each electrode but also for the irreversible charge losses. In this paper a LNMO-nano TiO 2 Li-ion cell with liquid electrolyte is presented: two innovative approaches on both the cathode and the anode sides were developed in order to mitigate the electrolyte decomposition upon cycling. In particular the LNMO surface was coated with ZnO in order to minimize the surface reactivity, and the TiO 2 nanoparticles where activated by incorporating nano-lithium in the electrode formulation to compensate for the irreversible capacity loss in the first cycle. With these strategies we were able to assemble balanced Li-ion coin cells thus avoiding the use of electrolyte additives and more hazardous and expensive ex-situ SEI preforming chemical or electrochemical procedures.

Guided Lithium Metal Deposition and Improved Lithium Coulombic Efficiency through Synergistic Effects of LiAsF 6 and Cyclic Carbonate Additives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Xiaodi; Zhang, Yaohui; Engelhard, Mark H.

Spatial and morphology control over lithium (Li) metal nucleation/growth, as well as improving Li Coulombic efficiency (CE) are of the most challenging issues for rechargeable Li metal batteries. Here, we report that LiAsF6 and vinylene carbonate (VC) can work synergistically to address these challenges. It is revealed that AsF6- can be reduced to Li3As and LiF, which can act as seeds for Li growth and form a robust solid electrolyte interphase (SEI) layer, respectively. The addition of VC is critical because it not only enables uniform AsF6- reduction by passivating the defect sites on Cu substrate, but also improves themore » SEI layer flexibility during the reductive polymerization process. As a result, highly compact, uniform and dendrite-free Li film with vertically aligned columns structure can be obtained with greatly increased Li CE, and the Li metal batteries using the electrolyte with both LiAsF6 and VC additives can have much improved cycle life.« less

Interfacial reactions in lithium batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Zonghai; Amine, Rachid; Ma, Zi-Feng

The lithium-ion battery was first commercially introduced by Sony Corporation on 1991 using LiCoO 2 as the cathode material and mesocarbon microbeads as the anode material. After continuous research and development for 25 years, lithium-ion batteries have been the dominant energy storage devices for modern portable electronics, as well as for the emerging application for electric vehicles and smart grids. It has been a common sense that the success of lithium-ion technologies is rooted to the existence of a solid electrolyte interphase (SEI) that kinetically suppresses the parasitic reactions between the lithiated 2 graphitic anodes and the carbonate-based non-aqueous electrolytes.more » Recently, major attention has been paid to the importance of a similar passivation/protection layer on the surface of cathode materials, aiming for rational design of high-energy-density lithiumion batteries with extended cycle/calendar life. In this article, the physical model of the solid electrolyte interphase, as well as the recent research effort to under the nature and role SEI are summarized, and future perspectives on this important research field will also be presented.« less

Interfacial reactions in lithium batteries

DOE PAGES

Chen, Zonghai; Amine, Rachid; Ma, Zi-Feng; ...

2017-06-29

The lithium-ion battery was first commercially introduced by Sony Corporation on 1991 using LiCoO 2 as the cathode material and mesocarbon microbeads as the anode material. After continuous research and development for 25 years, lithium-ion batteries have been the dominant energy storage devices for modern portable electronics, as well as for the emerging application for electric vehicles and smart grids. It has been a common sense that the success of lithium-ion technologies is rooted to the existence of a solid electrolyte interphase (SEI) that kinetically suppresses the parasitic reactions between the lithiated 2 graphitic anodes and the carbonate-based non-aqueous electrolytes.more » Recently, major attention has been paid to the importance of a similar passivation/protection layer on the surface of cathode materials, aiming for rational design of high-energy-density lithiumion batteries with extended cycle/calendar life. In this article, the physical model of the solid electrolyte interphase, as well as the recent research effort to under the nature and role SEI are summarized, and future perspectives on this important research field will also be presented.« less

Fluorinated reduced graphene oxide as a protective layer on the metallic lithium for application in the high energy batteries.

PubMed

Bobnar, Jernej; Lozinšek, Matic; Kapun, Gregor; Njel, Christian; Dedryvère, Rémi; Genorio, Boštjan; Dominko, Robert

2018-04-11

Metallic lithium is considered to be one of the most promising anode materials since it offers high volumetric and gravimetric energy densities when combined with high-voltage or high-capacity cathodes. However, the main impediment to the practical applications of metallic lithium is its unstable solid electrolyte interface (SEI), which results in constant lithium consumption for the formation of fresh SEI, together with lithium dendritic growth during electrochemical cycling. Here we present the electrochemical performance of a fluorinated reduced graphene oxide interlayer (FGI) on the metallic lithium surface, tested in lithium symmetrical cells and in combination with two different cathode materials. The FGI on the metallic lithium exhibit two roles, firstly it acts as a Li-ion conductive layer and electronic insulator and secondly, it effectively suppresses the formation of high surface area lithium (HSAL). An enhanced electrochemical performance of the full cell battery system with two different types of cathodes was shown in the carbonate or in the ether based electrolytes. The presented results indicate a potential application in future secondary Li-metal batteries.

In situ SEM Study of Lithium Intercalation in individual V 2O 5 Nanowires

DOE PAGES

Strelcov, Evgheni; Cothren, Joshua E.; Leonard, Donovan N.; ...

2015-01-08

Progress in rational engineering of Li-ion batteries requires better understanding of the electrochemical processes and accompanying transformations in the electrode materials on multiple length scales. In spite of recent progress in utilizing transmission electron microscopy (TEM) to analyze these materials, in situ scanning electron microscopy (SEM) was mostly overlooked as a powerful tool that allows probing these phenomena on the nano and mesoscale. In this paper, we report on in situ SEM study of lithiation in a V 2O 5-based single-nanobelt battery with ionic liquid electrolyte. Coupled with cyclic voltammetry measurements, in situ SEM revealed the peculiarities of subsurface intercalation,more » formation of solid-electrolyte interface (SEI) and electromigration of liquid. We observed that single-crystalline vanadia nanobelts do not undergo large-scale amorphization or fracture during electrochemical cycling, but rather transform topochemically with only a slight shape distortion. Lastly, the SEI layer seems to have significant influence on the lithium ion diffusion and overall capacity of the single-nanobelt battery.« less

Regulation of male germ cell cycle arrest and differentiation by DND1 is modulated by genetic background

PubMed Central

Cook, Matthew S.; Munger, Steven C.; Nadeau, Joseph H.; Capel, Blanche

2011-01-01

Human germ cell tumors show a strong sensitivity to genetic background similar to Dnd1Ter/Ter mutant mice, where testicular teratomas arise only on the 129/SvJ genetic background. The introduction of the Bax mutation onto mixed background Dnd1Ter/Ter mutants, where teratomas do not typically develop, resulted in a high incidence of teratomas. However, when Dnd1Ter/Ter; Bax–/– double mutants were backcrossed to C57BL/6J, no tumors arose. Dnd1Ter/Ter germ cells show a strong downregulation of male differentiation genes including Nanos2. In susceptible strains, where teratomas initiate around E15.5-E17.5, many mutant germ cells fail to enter mitotic arrest in G0 and do not downregulate the pluripotency markers NANOG, SOX2 and OCT4. We show that DND1 directly binds a group of transcripts that encode negative regulators of the cell cycle, including p27Kip1 and p21Cip1. P27Kip1 and P21Cip1 protein are both significantly decreased in Dnd1Ter/Ter germ cells on all strain backgrounds tested, strongly suggesting that DND1 regulates mitotic arrest in male germ cells through translational regulation of cell cycle genes. Nonetheless, in C57BL/6J mutants, germ cells arrest prior to M-phase of the cell cycle and downregulate NANOG, SOX2 and OCT4. Consistent with their ability to rescue cell cycle arrest, C57BL/6J germ cells overexpress negative regulators of the cell cycle relative to 129/SvJ. This work suggests that reprogramming of pluripotency in germ cells and prevention of tumor formation requires cell cycle arrest, and that differences in the balance of cell cycle regulators between 129/SvJ and C57BL/6 might underlie differences in tumor susceptibility. PMID:21115610

DACH1 regulates cell cycle progression of myeloid cells through the control of cyclin D, Cdk 4/6 and p21{sup Cip1}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Jae-Woong; Kim, Hyeng-Soo; Kim, Seonggon

2012-03-30

Highlights: Black-Right-Pointing-Pointer DACH1 increases cyclin D, F and Cdk 1, 4, 6 in mouse myeloid progenitor cells. Black-Right-Pointing-Pointer The knockdown of DACH1 blocked the cell cycle progression of HL-60 cells. Black-Right-Pointing-Pointer The novel effect of DACH1 related with cell cycle regulation and leukemogenesis. -- Abstract: The cell-fate determination factor Dachshund, a component of the Retinal Determination Gene Network (RDGN), has a role in breast tumor proliferation through the repression of cyclin D1 and several key regulators of embryonic stem cell function, such as Nanog and Sox2. However, little is known about the role of DACH1 in a myeloid lineage asmore » a cell cycle regulator. Here, we identified the differential expression levels of extensive cell cycle regulators controlled by DACH1 in myeloid progenitor cells. The forced expression of DACH1 induced p27{sup Kip1} and repressed p21{sup Cip1}, which is a pivotal characteristic of the myeloid progenitor. Furthermore, DACH1 significantly increased the expression of cyclin D1, D3, F, and Cdk 1, 4, and 6 in myeloid progenitor cells. The knockdown of DACH1 blocked the cell cycle progression of HL-60 promyeloblastic cells through the decrease of cyclin D1, D3, F, and Cdk 1, 4, and 6 and increase in p21{sup Cip1}, which in turn decreased the phosphorylation of the Rb protein. The expression of Sox2, Oct4, and Klf4 was significantly up-regulated by the forced expression of DACH1 in mouse myeloid progenitor cells.« less

Estrogens regulate the expression of NHERF1 in normal colon during the reproductive cycle of Wistar rats.

PubMed

Cuello-Carrión, F Darío; Troncoso, Mariana; Guiñazu, Elina; Valdez, Susana R; Fanelli, Mariel A; Ciocca, Daniel R; Kreimann, Erica L

2010-12-01

In breast cancer cell lines, the Na(+)/H(+) exchanger regulator factor 1 (NHERF1) gene is regulated at the transcriptional level by estrogens, the protein expression levels correlate with the presence of estrogen receptors and the effect is blocked by anti-estrogens. However, there is limited information regarding the regulation of NHERF1 by estrogens in normal colon tissue. The NHERF1 protein has an important role in the maintenance of the intestine ultrastructure. NHERF1-deficient mice showed defects in the intestinal microvilli as well as molecular alterations in brush border membrane proteins. Here, we have studied the expression of NHERF1 in normal rat colon and uterus during the reproductive cycle of Wistar rats. We found that NHERF1 expression in rat colon during the estral cycle is modified by estrogen levels: higher expression of NHERF1 was observed during the proestrous and estrous stages and lower expression in diestrous 1 when estrogen levels decreased. In uterus, NHERF1 was expressed in the apical region of the luminal epithelium and glands in all stages of the estral cycle, and in both colon and uterus, the expression was independent of the proliferation status. Our results show that NHERF1 expression is regulated by estrogens in colon during the rat estral cycle.

Telecommunications, navigation and information management concept overview for the Space Exploration Initiative program

NASA Technical Reports Server (NTRS)

Bell, Jerome A.; Stephens, Elaine; Barton, Gregg

1991-01-01

An overview is provided of the Space Exploration Initiative (SEI) concepts for telecommunications, information systems, and navigation (TISN), and engineering and architecture issues are discussed. The SEI program data system is reviewed to identify mission TISN interfaces, and reference TISN concepts are described for nominal, degraded, and mission-critical data services. The infrastructures reviewed include telecommunications for robotics support, autonomous navigation without earth-based support, and information networks for tracking and data acquisition. Four options for TISN support architectures are examined which relate to unique SEI exploration strategies. Detailed support estimates are given for: (1) a manned stay on Mars; (2) permanent lunar and Martian settlements; short-duration missions; and (4) systematic exploration of the moon and Mars.

Senescence-associated microRNAs target cell cycle regulatory genes in normal human lung fibroblasts.

PubMed

Markopoulos, Georgios S; Roupakia, Eugenia; Tokamani, Maria; Vartholomatos, George; Tzavaras, Theodore; Hatziapostolou, Maria; Fackelmayer, Frank O; Sandaltzopoulos, Raphael; Polytarchou, Christos; Kolettas, Evangelos

2017-10-01

Senescence recapitulates the ageing process at the cell level. A senescent cell stops dividing and exits the cell cycle. MicroRNAs (miRNAs) acting as master regulators of transcription, have been implicated in senescence. In the current study we investigated and compared the expression of miRNAs in young versus senescent human fibroblasts (HDFs), and analysed the role of mRNAs expressed in replicative senescent HFL-1 HDFs. Cell cycle analysis confirmed that HDFs accumulated in G 1 /S cell cycle phase. Nanostring analysis of isolated miRNAs from young and senescent HFL-1 showed that a distinct set of 15 miRNAs were significantly up-regulated in senescent cells including hsa-let-7d-5p, hsa-let-7e-5p, hsa-miR-23a-3p, hsa-miR-34a-5p, hsa-miR-122-5p, hsa-miR-125a-3p, hsa-miR-125a-5p, hsa-miR-125b-5p, hsa-miR-181a-5p, hsa-miR-221-3p, hsa-miR-222-3p, hsa-miR-503-5p, hsa-miR-574-3p, hsa-miR-574-5p and hsa-miR-4454. Importantly, pathway analysis of miRNA target genes down-regulated during replicative senescence in a public RNA-seq data set revealed a significant high number of genes regulating cell cycle progression, both G 1 /S and G 2 /M cell cycle phase transitions and telomere maintenance. The reduced expression of selected miRNA targets, upon replicative and oxidative-stress induced senescence, such as the cell cycle effectors E2F1, CcnE, Cdc6, CcnB1 and Cdc25C was verified at the protein and/or RNA levels. Induction of G1/S cell cycle phase arrest and down-regulation of cell cycle effectors correlated with the up-regulation of miR-221 upon both replicative and oxidative stress-induced senescence. Transient expression of miR-221/222 in HDFs promoted the accumulation of HDFs in G1/S cell cycle phase. We propose that miRNAs up-regulated during replicative senescence may act in concert to induce cell cycle phase arrest and telomere erosion, establishing a senescent phenotype. Copyright © 2017 Elsevier Inc. All rights reserved.

Mcl1 regulates the terminal mitosis of neural precursor cells in the mammalian brain through p27Kip1.

PubMed

Hasan, S M Mahmudul; Sheen, Ashley D; Power, Angela M; Langevin, Lisa Marie; Xiong, Jieying; Furlong, Michael; Day, Kristine; Schuurmans, Carol; Opferman, Joseph T; Vanderluit, Jacqueline L

2013-08-01

Cortical development requires the precise timing of neural precursor cell (NPC) terminal mitosis. Although cell cycle proteins regulate terminal mitosis, the factors that influence the cell cycle machinery are incompletely understood. Here we show in mice that myeloid cell leukemia 1 (Mcl1), an anti-apoptotic Bcl-2 protein required for the survival of NPCs, also regulates their terminal differentiation through the cell cycle regulator p27(Kip1). A BrdU-Ki67 cell profiling assay revealed that in utero electroporation of Mcl1 into NPCs in the embryonic neocortex increased NPC cell cycle exit (the leaving fraction). This was further supported by a decrease in proliferating NPCs (Pax6(+) radial glial cells and Tbr2(+) neural progenitors) and an increase in differentiating cells (Dcx(+) neuroblasts and Tbr1(+) neurons). Similarly, BrdU birth dating demonstrated that Mcl1 promotes premature NPC terminal mitosis giving rise to neurons of the deeper cortical layers, confirming their earlier birthdate. Changes in Mcl1 expression within NPCs caused concomitant changes in the levels of p27(Kip1) protein, a key regulator of NPC differentiation. Furthermore, in the absence of p27(Kip1), Mcl1 failed to induce NPC cell cycle exit, demonstrating that p27(Kip1) is required for Mcl1-mediated NPC terminal mitosis. In summary, we have identified a novel physiological role for anti-apoptotic Mcl1 in regulating NPC terminal differentiation.

Post mortem analysis of fatigue mechanisms in LiNi0.8Co0.15Al0.05O2 - LiNi0.5Co0.2Mn0.3O2 - LiMn2O4/graphite lithium ion batteries

NASA Astrophysics Data System (ADS)

Lang, Michael; Darma, Mariyam Susana Dewi; Kleiner, Karin; Riekehr, Lars; Mereacre, Liuda; Ávila Pérez, Marta; Liebau, Verena; Ehrenberg, Helmut

2016-09-01

The fatigue of commercial lithium ion batteries after long-term cycling at two different temperatures and cycling rates is investigated. The cells are opened after cycling and post-mortem analysis are conducted. Two main contributions to the capacity loss of the batteries are revealed. The loss of active lithium leads to a relative shift between anodes and cathodes potentials. A growth of the solid electrolyte interface (SEI) on the anode is determined as well as the formation of lithium fluoride species as an electrolyte decomposition product. Those effects are reinforced by increasing cycling rates from 1C/2C (charge/discharge) to 2C/3C as well as by increasing cycling temperatures from 25 °C to 40 °C. The other contribution to the capacity loss originates from a fatigue of the blended cathodes consisting of LiNi0.5Co0.2Mn0.3O2 (NCM), LiNi0.8Co0.15Al0.05O2 (NCA) and LiMn2O4 (LMO). Phase-specific capacity losses and fatigue mechanisms are identified. The layered oxides tend to form microcracks and reveal changes of the surface structure leading to a worsening of the lithium kinetics. The cathode exhibits a loss of manganese at 40 °C cycling temperature. Cycling at 40 °C instead of 25 °C has the major impact on cathodes capacity loss, while cycling at 2C/3C rates barely influences it.

The Effect of Electrolyte Additives upon the Lithium Kinetics of Li-Ion Cells Containing MCMB and LiNi(x)Co(1-x)O2 Electrodes and Exposed to High Temperatures

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Gozdz, A. S.; Mani, S.

2009-01-01

With the intent of improving the performance of lithium-ion cells at high temperatures, we have investigated the use of a number of electrolyte additives in experimental MCMB- Li(x)Ni(y)Co(1-y)O2 cells, which were exposed to temperatures as high as 80 C. In the present work, we have evaluated the use of a number of additives, namely vinylene carbonate (VC), dimethyl acetamide (DMAc), and mono-fluoroethylene carbonate (FEC), in an electrolyte solution anticipated to perform well at warm temperature (i.e., 1.0M LiPF6 in EC+EMC (50:50 v/v %). In addition, we have explored the use of novel electrolyte additives, namely lithium oxalate and lithium tetraborate. In addition to determining the capacity and power losses at various temperatures sustained as a result of high temperature cycling (cycling performed at 60 and 80 C), the three-electrode MCMB-Li(x)Ni(y)Co(1-y)O2 cells (lithium reference) enabled us to study the impact of high temperature storage upon the solid electrolyte interphase (SEI) film characteristics on carbon anodes (MCMB-based materials), metal oxide cathodes, and the subsequent impact upon electrode kinetics.

Results of SEI Independent Research and Development Projects

DTIC Science & Technology

2008-07-01

and the processes being followed. The coordination occurs uti- lizing one or more different media types. Figure 2-2: Factors Impacting Coordination...use of one media and be continued using another. Table 2-2: Styles of Coordination and Type of Tool Used for Each Style Teleconference E-mail... social and legal issues, stakeholder management, and training and education. These relationships are shown in Figure 4-1. 19 | CMU/SEI-2008-TR

Influence of temperature on the aging behavior of 18650-type lithium ion cells: A comprehensive approach combining electrochemical characterization and post-mortem analysis

NASA Astrophysics Data System (ADS)

Friesen, Alex; Mönnighoff, Xaver; Börner, Markus; Haetge, Jan; Schappacher, Falko M.; Winter, Martin

2017-02-01

The understanding of the aging behavior of lithium ion batteries in automotive and energy storage applications is essential for the acceptance of the technology. Therefore, aging experiments were conducted on commercial 18650-type state-of-the-art cells to determine the influence of the temperature during electrochemical cycling on the aging behavior of the different cell components. The cells, based on Li(Ni0.5Co0.2Mn0.3)O2 (NCM532)/graphite, were aged at 20 °C and 45 °C to different states of health. The electrochemical performance of the investigated cells shows remarkable differences depending on the cycling temperature. At contrast to the expected behavior, the cells cycled at 45 °C show a better electrochemical performance over lifetime than the cells cycled at 20 °C. Comprehensive post-mortem analyses revealed the main aging mechanisms, showing a complex interaction between electrodes and electrolyte. The main aging mechanisms of the cells cycled at 45 °C differ strongly at contrast to cells cycled at 20 °C. A strong correlation between the formed SEI, the electrolyte composition and the electrochemical performance over lifetime was observed.

Interaction of CuS and sulfur in Li-S battery system

DOE PAGES

Sun, Ke; Su, Dong; Zhang, Qing; ...

2015-10-27

Lithium-Sulfur (Li-S) battery has been a subject of intensive research in recent years due to its potential to provide much higher energy density and lower cost than the current state of the art lithiumion battery technology. In this work, we have investigated Cupric Sulfide (CuS) as a capacitycontributing conductive additive to the sulfur electrode in a Li-S battery. Galvanostatic charge/discharge cycling has been used to compare the performance of both sulfur electrodes and S:CuS hybrid electrodes with various ratios. We found that the conductive CuS additive enhanced the utilization of the sulfur cathode under a 1C rate discharge. However, undermore » a C/10 discharge rate, S:CuS hybrid electrodes exhibited lower sulfur utilization in the first discharge and faster capacity decay in later cycles than a pure sulfur electrode due to the dissolution of CuS. The CuS dissolution is found to be the result of strong interaction between the soluble low order polysulfide Li 2S 3 and CuS. As a result, we identified the presence of conductive copper-containing sulfides at the cycled lithium anode surface, which may degrade the effectiveness of the passivation function of the solid-electrolyte-interphase (SEI) layer, accounting for the poor cycling performance of the S:CuS hybrid cells at low rate.« less

Facile Fabrication of Ethoxy-Functional Polysiloxane Wrapped LiNi0.6Co0.2Mn0.2O2 Cathode with Improved Cycling Performance for Rechargeable Li-Ion Battery.

PubMed

Wang, Hao; Ge, Wujie; Li, Wen; Wang, Feng; Liu, Wenjing; Qu, Mei-Zhen; Peng, Gongchang

2016-07-20

Dealing with the water molecule on the surface of LiNi0.6Co0.2Mn0.2O2 (NCM) cathode and hydrogen fluoride in the electrolyte is one of the most difficult challenges in Li-ion battery research. In this paper, the surface polymerization of tetraethyl orthosilicate (TEOS) on NCM to generate ethoxy-functional polysiloxane (EPS) wrapped NCM (E-NCM) cathode under mild conditions and without any additions is utilized to solve this intractable problem. The differential scanning calorimetry, transmission electron microscopy, and X-ray photoelectron spectroscopy results show that the formed amorphous coating can provide a protective shell to improve the NCM thermal stability, suppress the thickening of the solid electrolyte interphase (SEI) layer, and scavenge HF in the electrolyte. The E-NCM composite with 2 mol % EPS delivers a high discharge capacity retention of 84.9% after 100 cycles at a 1 C discharge rate in the 2.8-4.3 V potential range at 55 °C. Moreover, electrochemical impedance spectroscopy measurements reveal that the EPS coating could alleviate the impedance rise during cycling especially at an elevated temperature. Therefore, the fabricated E-NCM cathode with long-term cycling and thermal stability is a promising candidate for use in a high-energy Li-ion battery.

Scalable Production of the Silicon-Tin Yin-Yang Hybrid Structure with Graphene Coating for High Performance Lithium-Ion Battery Anodes.

PubMed

Jin, Yan; Tan, Yingling; Hu, Xiaozhen; Zhu, Bin; Zheng, Qinghui; Zhang, Zijiao; Zhu, Guoying; Yu, Qian; Jin, Zhong; Zhu, Jia

2017-05-10

Alloy anodes possessed of high theoretical capacity show great potential for next-generation advanced lithium-ion battery. Even though huge volume change during lithium insertion and extraction leads to severe problems, such as pulverization and an unstable solid-electrolyte interphase (SEI), various nanostructures including nanoparticles, nanowires, and porous networks can address related challenges to improve electrochemical performance. However, the complex and expensive fabrication process hinders the widespread application of nanostructured alloy anodes, which generate an urgent demand of low-cost and scalable processes to fabricate building blocks with fine controls of size, morphology, and porosity. Here, we demonstrate a scalable and low-cost process to produce a porous yin-yang hybrid composite anode with graphene coating through high energy ball-milling and selective chemical etching. With void space to buffer the expansion, the produced functional electrodes demonstrate stable cycling performance of 910 mAh g -1 over 600 cycles at a rate of 0.5C for Si-graphene "yin" particles and 750 mAh g -1 over 300 cycles at 0.2C for Sn-graphene "yang" particles. Therefore, we open up a new approach to fabricate alloy anode materials at low-cost, low-energy consumption, and large scale. This type of porous silicon or tin composite with graphene coating can also potentially play a significant role in thermoelectrics and optoelectronics applications.

Improved electrochemical performance of spinel LiMn(1.5)Ni(0.5)O4 through MgF2 nano-coating.

PubMed

Wu, Qing; Zhang, Xiaoping; Sun, Shuwei; Wan, Ning; Pan, Du; Bai, Ying; Zhu, Huiyuan; Hu, Yong-Sheng; Dai, Sheng

2015-10-14

A spinel LiMn1.5Ni0.5O4 (LMNO) cathode material synthesized by a sol-gel method is modified by MgF2 nano-coating via a wet coating strategy. The results of X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) showed that the MgF2 nano-coating layers do not physically change the bulk structure of the pristine material. Compared with the pristine compound, the MgF2-coated LMNO electrodes display enhanced cycling stabilities. Particularly, the 5 wt% MgF2-coated LMNO demonstrates the best reversibility, with a capacity retention of 89.9% after 100 cycles, much higher than that of the pristine material, 69.3%. The dQ/dV analysis and apparent Li(+) diffusion coefficient calculation prove that the kinetic properties are enhanced after MgF2 surface modification, which partly explains the improved electrochemical performances. Electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR) data confirm that the MgF2 coating layer helps in suppressing the fast growth of the solid electrolyte interface (SEI) film in repeated cycling, which effectively stabilizes the spinel structure. Additionally, differential scanning calorimetry (DSC) tests show that the MgF2 nano-coating layer also helps in enhancing the thermal stability of the LMNO cathode.

The Yeast Cyclin-Dependent Kinase Routes Carbon Fluxes to Fuel Cell Cycle Progression.

PubMed

Ewald, Jennifer C; Kuehne, Andreas; Zamboni, Nicola; Skotheim, Jan M

2016-05-19

Cell division entails a sequence of processes whose specific demands for biosynthetic precursors and energy place dynamic requirements on metabolism. However, little is known about how metabolic fluxes are coordinated with the cell division cycle. Here, we examine budding yeast to show that more than half of all measured metabolites change significantly through the cell division cycle. Cell cycle-dependent changes in central carbon metabolism are controlled by the cyclin-dependent kinase (Cdk1), a major cell cycle regulator, and the metabolic regulator protein kinase A. At the G1/S transition, Cdk1 phosphorylates and activates the enzyme Nth1, which funnels the storage carbohydrate trehalose into central carbon metabolism. Trehalose utilization fuels anabolic processes required to reliably complete cell division. Thus, the cell cycle entrains carbon metabolism to fuel biosynthesis. Because the oscillation of Cdk activity is a conserved feature of the eukaryotic cell cycle, we anticipate its frequent use in dynamically regulating metabolism for efficient proliferation. Copyright © 2016 Elsevier Inc. All rights reserved.

SOFTWARE ENGINEERING INSTITUTE (SEI)

EPA Science Inventory

The Software Engineering Institute (SEI) is a federally funded research and development center established in 1984 by the U.S. Department of Defense and operated by Carnegie Mellon University. SEI has a broad charter to provide leadership in the practice of software engineering t...

Immobilization of Anions on Polymer Matrices for Gel Electrolytes with High Conductivity and Stability in Lithium Ion Batteries.

PubMed

Wang, Shih-Hong; Lin, Yong-Yi; Teng, Chiao-Yi; Chen, Yen-Ming; Kuo, Ping-Lin; Lee, Yuh-Lang; Hsieh, Chien-Te; Teng, Hsisheng

2016-06-15

This study reports on a high ionic-conductivity gel polymer electrolyte (GPE), which is supported by a TiO2 nanoparticle-decorated polymer framework comprising poly(acrylonitrile-co-vinyl acetate) blended with poly(methyl methacrylate), i.e. , PAVM: TiO2. High conductivity TiO2 is achieved by causing the PAVM:TiO2 polymer framework to swell in 1 M LiPF6 in carbonate solvent. Raman analysis results demonstrate that the poly(acrylonitrile) (PAN) segments and TiO2 nanoparticles strongly adsorb PF6(-) anions, thereby generating 3D percolative space-charge pathways surrounding the polymer framework for Li(+)-ion transport. The ionic conductivity of TiO2 is nearly 1 order of magnitude higher than that of commercial separator-supported liquid electrolyte (SLE). TiO2 has a high Li(+) transference number (0.7), indicating that most of the PF6(-) anions are stationary, which suppresses PF6(-) decomposition and substantially enlarges the voltage that can be applied to TiO2 (to 6.5 V vs Li/Li(+)). Immobilization of PF6(-) anions also leads to the formation of stable solid-electrolyte interface (SEI) layers in a full-cell graphite|electrolyte|LiFePO4 battery, which exhibits low SEI and overall resistances. The graphite|electrolyte|LiFePO4 battery delivers high capacity of 84 mAh g(-1) even at 20 C and presents 90% and 71% capacity retention after 100 and 1000 charge-discharge cycles, respectively. This study demonstrates a GPE architecture comprising 3D space charge pathways for Li(+) ions and suppresses anion decomposition to improve the stability and lifespan of the resulting LIBs.

Required number of records for ASCE/SEI 7 ground-motion scaling procedure

USGS Publications Warehouse

Reyes, Juan C.; Kalkan, Erol

2011-01-01

The procedures and criteria in 2006 IBC (International Council of Building Officials, 2006) and 2007 CBC (International Council of Building Officials, 2007) for the selection and scaling ground-motions for use in nonlinear response history analysis (RHA) of structures are based on ASCE/SEI 7 provisions (ASCE, 2005, 2010). According to ASCE/SEI 7, earthquake records should be selected from events of magnitudes, fault distance, and source mechanisms that comply with the maximum considered earthquake, and then scaled so that the average value of the 5-percent-damped response spectra for the set of scaled records is not less than the design response spectrum over the period range from 0.2Tn to 1.5Tn sec (where Tn is the fundamental vibration period of the structure). If at least seven ground-motions are analyzed, the design values of engineering demand parameters (EDPs) are taken as the average of the EDPs determined from the analyses. If fewer than seven ground-motions are analyzed, the design values of EDPs are taken as the maximum values of the EDPs. ASCE/SEI 7 requires a minimum of three ground-motions. These limits on the number of records in the ASCE/SEI 7 procedure are based on engineering experience, rather than on a comprehensive evaluation. This study statistically examines the required number of records for the ASCE/SEI 7 procedure, such that the scaled records provide accurate, efficient, and consistent estimates of" true" structural responses. Based on elastic-perfectly-plastic and bilinear single-degree-of-freedom systems, the ASCE/SEI 7 scaling procedure is applied to 480 sets of ground-motions. The number of records in these sets varies from three to ten. The records in each set were selected either (i) randomly, (ii) considering their spectral shapes, or (iii) considering their spectral shapes and design spectral-acceleration value, A(Tn). As compared to benchmark (that is, "true") responses from unscaled records using a larger catalog of ground-motions, it is demonstrated that the ASCE/SEI 7 scaling procedure is overly conservative if fewer than seven ground-motions are employed. Utilizing seven or more randomly selected records provides a more accurate estimate of the EDPs accompanied by reduced record-to-record variability of the responses. Consistency in accuracy and efficiency is achieved only if records are selected on the basis of their spectral shape and A(Tn).

Rapid differentiation of Staphylococcus aureus isolates harbouring egc loci with pseudogenes psient1 and psient2 and the selu or seluv gene using PCR-RFLP.

PubMed

Collery, Mark M; Smyth, Cyril J

2007-02-01

The egc locus of Staphylococus aureus harbours two enterotoxin genes (seg and sei) and three enterotoxin-like genes (selm, seln and selo). Between the sei and seln genes are located two pseudogenes, psient1 and psient2, or the selu or seluv gene. While these two alternative sei-seln intergenic regions can be distinguished by PCR, to date, DNA sequencing has been the only confirmatory option because of the very high degree of sequence similarity between egc loci bearing the pseudogenes and the selu or seluv gene. In silico restriction enzyme digestion of genomic regions encompassing the egc locus from the 3' end of the sei gene through the 5' first quarter of the seln gene allowed pseudogene- and selu- or seluv-bearing egc loci to be distinguished by PCR-RFLP. Experimental application of these findings demonstrated that endonuclease HindIII cleaved PCR amplimers bearing pseudogenes but not those with a selu or seluv gene, while selu- or seluv-bearing amplimers were susceptible to cleavage by endonuclease HphI, but not by endonuclease HindIII. The restriction enzyme BccI cleaved selu- or seluv-harbouring amplimers at a unique restriction site created by their signature 15 bp insertion compared with pseudogene-bearing amplimers, thereby allowing distinction of these egc loci. PCR-RFLP analysis using these restriction enzymes provides a rapid, easy to interpret alternative to DNA sequencing for verification of PCR findings on the nature of an egc locus type, and can also be used for the primary identification of the intergenic sei-seln egc locus type.

Regulation of TGF-β signaling, exit from the cell cycle, and cellular migration through cullin cross-regulation: SCF-FBXO11 turns off CRL4-Cdt2.

PubMed

Abbas, Tarek; Keaton, Mignon; Dutta, Anindya

2013-07-15

Deregulation of the cell cycle and genome instability are common features of cancer cells and various mechanisms exist to preserve the integrity of the genome and guard against cancer. The cullin 4-RING ubiquitin ligase (CRL4) with the substrate receptor Cdt2 (CRL4 (Cdt2)) promotes cell cycle progression and prevents genome instability through ubiquitylation and degradation of Cdt1, p21, and Set8 during S phase of the cell cycle and following DNA damage. Two recently published studies report the ubiquitin-dependent degradation of Cdt2 via the cullin 1-RING ubiquitin ligase (CRL1) in association with the substrate specificity factor and tumor suppressor FBXO11 (CRL1 (FBXO11)). The newly identified pathway restrains the activity of CRL4 (Cdt2) on p21 and Set8 and regulates cellular response to TGF-β, exit from the cell cycle and cellular migration. Here, we show that the CRL1 (FBXO11) also promotes the degradation of Cdt2 during an unperturbed cell cycle to promote efficient progression through S and G 2/M phases of the cell cycle. We discuss how this new method of regulating the abundance of Cdt2 participates in various cellular activities.

SiO2-coated LiNi0.915Co0.075Al0.01O2 cathode material for rechargeable Li-ion batteries.

PubMed

Zhou, Pengfei; Zhang, Zhen; Meng, Huanju; Lu, Yanying; Cao, Jun; Cheng, Fangyi; Tao, Zhanliang; Chen, Jun

2016-11-24

We reported a one-step dry coating of amorphous SiO 2 on spherical Ni-rich layered LiNi 0.915 Co 0.075 Al 0.01 O 2 (NCA) cathode materials. Combined characterization of XRD, EDS mapping, and TEM indicates that a SiO 2 layer with an average thickness of ∼50 nm was uniformly coated on the surface of NCA microspheres, without inducing any change of the phase structure and morphology. Electrochemical tests show that the 0.2 wt% SiO 2 -coated NCA material exhibits enhanced cyclability and rate properties, combining with better thermal stability compared with those of pristine NCA. For example, 0.2 wt% SiO 2 -coated NCA delivers a high specific capacity of 181.3 mA h g -1 with a capacity retention of 90.7% after 50 cycles at 1 C rate and 25 °C. Moreover, the capacity retention of this composite at 60 °C is 12.5% higher than that of pristine NCA at 1 C rate after 50 cycles. The effects of SiO 2 coating on the electrochemical performance of NCA are investigated by EIS, CV, and DSC tests, the improved performance is attributed to the surface coating layer of amorphous SiO 2 , which effectively suppresses side reactions between NCA and electrolytes, decreases the SEI layer resistance, and retards the growth of charge-transfer resistance, thus enhancing structural and cycling stability of NCA.

SEI Approach to Harmonization

DTIC Science & Technology

2008-07-18

PAs and PLA ISO 15504 and ISO 12207 COBIT EFQM ISO 9001 Improvement Method Elements Change management techniques: IDEAL and Six Sigma...Multimodel Improvement in Practice 12 SEI Webinar Series Northrop Grumman Mission Systems • CMMI, Six Sigma, ISO , KM • ―.. accelerate achievement of Levels...CMMI, ITIL, ISO 9001, P-CMM  ―Integrated Quality Mgmt System‖ • ―…development center…reduce[d]...in-process failure costs...5 to 1%...‖ Wipro • ISO

Environmental Influences on Diel Calling Behavior in Baleen Whales

DTIC Science & Technology

2013-09-30

to allow known calls (e.g., right whale upcall and gunshot, fin whale 20- Hz pulses, humpback whale downsweeps, sei whale low-frequency downsweeps...fin, humpback , sei, and North Atlantic right whales . Real-time detections were evaluated after recovery of the gliders by (1) comparing the acoustic...from both an aircraft and ship. The overall false detection rate for individual calls was 14%, and for right, humpback , and fin whales , false

Results of SEI Independent Research and Development Projects

DTIC Science & Technology

2011-02-01

ft’s Bit- poten- hout a ut de- r for CMU/SEI-2011-TR-002 | 8 more systems to install them. The implication to the Department of Defense and...Computing, June 2011. 2.7.1 Bibliography Challener, David; Yoder, K.; Catherman, R .; Saford, D.; & Van Doom, L. A Practical Guide to Trusted...number of publications and presentations: Brown, N.; Nord, R .; & Ozkaya, I. “Enabling Agility Through Architecture.” CrossTalk 23, 6 (November

The Domain-Specific Software Architecture Program

DTIC Science & Technology

1992-06-01

Kang, K.C; Cohen, S.C: Jess, J.A; Novak, W.E; Peterson, A.S. Feature- Oriented Domain Analysis ( FODA ) Feasibility Study. (CMU/SEI-90-TR-21, ADA235785...perspective of a con- trols engineer solving a problem using an iterative process of simulation and analysis . The CMU/SEI-92-SR-9 1 I ~math AnalysislP...for schedulability analysis and Markov processes for the determination of reliability. Software architectures are derived from these formal models. ORA

Space exploration initiative (SEI) logistics support lessons from the DoD

NASA Astrophysics Data System (ADS)

Cox, John R.; McCoy, Walbert G.; Jenkins, Terence

Proven and innovative logistics management approaches and techniques used for developing and supporting DoD and Strategic Defense Initiative Office (SDIO) systems are described on the basis of input from DoD to the SEI Synthesis Group; SDIO-developed logistics initiatives, innovative tools, and methodologies; and logistics planning support provided to the NASA/Johnson Planet Surface System Office. The approach is tailored for lunar/Martian surface operations, and provides guidelines for the development and management of a crucial element of the SEI logistics support program. A case study is presented which shows how incorporation of DoD's proven and innovative logistics management approach, tools, and techniques can substantially benefit early logistics planning for SEI, while also implementing many of DoD's recommendations for SEI.

Pannexins Are Potential New Players in the Regulation of Cerebral Homeostasis during Sleep-Wake Cycle

PubMed Central

Shestopalov, Valery I.; Panchin, Yuri; Tarasova, Olga S.; Gaynullina, Dina; Kovalzon, Vladimir M.

2017-01-01

During brain homeostasis, both neurons and astroglia release ATP that is rapidly converted to adenosine in the extracellular space. Pannexin-1 (Panx1) hemichannels represent a major conduit of non-vesicular ATP release from brain cells. Previous studies have shown that Panx1−/− mice possess severe disruption of the sleep-wake cycle. Here, we review experimental data supporting the involvement of pannexins (Panx) in the coordination of fundamental sleep-associated brain processes, such as neuronal activity and regulation of cerebrovascular tone. Panx1 hemichannels are likely implicated in the regulation of the sleep-wake cycle via an indirect effect of released ATP on adenosine receptors and through interaction with other somnogens, such as IL-1β, TNFα and prostaglandin D2. In addition to the recently established role of Panx1 in the regulation of endothelium-dependent arterial dilation, similar signaling pathways are the major cellular component of neurovascular coupling. The new discovered role of Panx in sleep regulation may have broad implications in coordinating neuronal activity and homeostatic housekeeping processes during the sleep-wake cycle. PMID:28769767

Pannexins Are Potential New Players in the Regulation of Cerebral Homeostasis during Sleep-Wake Cycle.

PubMed

Shestopalov, Valery I; Panchin, Yuri; Tarasova, Olga S; Gaynullina, Dina; Kovalzon, Vladimir M

2017-01-01

During brain homeostasis, both neurons and astroglia release ATP that is rapidly converted to adenosine in the extracellular space. Pannexin-1 (Panx1) hemichannels represent a major conduit of non-vesicular ATP release from brain cells. Previous studies have shown that Panx1 -/- mice possess severe disruption of the sleep-wake cycle. Here, we review experimental data supporting the involvement of pannexins (Panx) in the coordination of fundamental sleep-associated brain processes, such as neuronal activity and regulation of cerebrovascular tone. Panx1 hemichannels are likely implicated in the regulation of the sleep-wake cycle via an indirect effect of released ATP on adenosine receptors and through interaction with other somnogens, such as IL-1β, TNFα and prostaglandin D2. In addition to the recently established role of Panx1 in the regulation of endothelium-dependent arterial dilation, similar signaling pathways are the major cellular component of neurovascular coupling. The new discovered role of Panx in sleep regulation may have broad implications in coordinating neuronal activity and homeostatic housekeeping processes during the sleep-wake cycle.

Multiple division cycles and long-term survival of hepatocytes are distinctly regulated by extracellular signal-regulated kinases ERK1 and ERK2.

PubMed

Frémin, Christophe; Bessard, Anne; Ezan, Frédéric; Gailhouste, Luc; Régeard, Morgane; Le Seyec, Jacques; Gilot, David; Pagès, Gilles; Pouysségur, Jacques; Langouët, Sophie; Baffet, Georges

2009-03-01

We investigated the specific role of the mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase 1 (ERK1)/ERK2 pathway in the regulation of multiple cell cycles and long-term survival of normal hepatocytes. An early and sustained epidermal growth factor (EGF)-dependent MAPK activation greatly improved the potential of cell proliferation. In this condition, almost 100% of the hepatocytes proliferated, and targeting ERK1 or ERK2 via RNA interference revealed the specific involvement of ERK2 in this regulation. However, once their first cell cycle was performed, hepatocytes failed to undergo a second round of replication and stayed blocked in G1 phase. We demonstrated that sustained EGF-dependent activation of the MAPK/ERK kinase (MEK)/ERK pathway was involved in this blockage as specific transient inhibition of the cascade repotentiated hepatocytes to perform a new wave of replication and multiple cell cycles. We identified this mechanism by showing that this blockage was in part supported by ERK2-dependent p21 expression. Moreover, continuous MEK inhibition was associated with a lower apoptotic engagement, leading to an improvement of survival up to 3 weeks. Using RNA interference and ERK1 knockout mice, we extended these results by showing that this improved survival was due to the specific inhibition of ERK1 expression/phosphorylation and did not involve ERK2. Our results emphasize that transient MAPK inhibition allows multiple cell cycles in primary cultures of hepatocytes and that ERK2 has a key role in the regulation of S phase entry. Moreover, we revealed a major and distinct role of ERK1 in the regulation of hepatocyte survival. Taken together, our results represent an important advance in understanding long-term survival and cell cycle regulation of hepatocytes.

New promising lithium malonatoborate salts for high voltage lithium ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Xiao -Guang; Wan, Shun; Guang, Hong Yu

Here, three new lithium salts, lithium difluoro-2-methyl-2-fluoromalonaoborate (LiDFMFMB), lithium difluoro-2-ethyl-2-fluoromalonaoborate (LiDFEFMB), and lithium difluoro-2-propyl-2-fluoro malonaoborate (LiDFPFMB), have been synthesized and evaluated for application in lithium ion batteries. These new salts are soluble in a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (1:2 by wt.) and 1.0 M salt solutions can be easily prepared. The ionic conductivities of these new salts are close to those of LiBF 4 and LiPF 6. Cyclic voltammograms reveal that these new salt based electrolytes can passivate both natural graphite and high voltage spinel LiNi 0.5Mn 1.5O 4 (LNMO) to form effective solidmore » electrolyte interphases (SEIs). In addition, these new salts based electrolytes exhibit good cycling stability with high coulombic efficiencies in both LiNi 0.5Mn 1.5O 4 and graphite based half-cells and full cells.« less

New promising lithium malonatoborate salts for high voltage lithium ion batteries

DOE PAGES

Sun, Xiao -Guang; Wan, Shun; Guang, Hong Yu; ...

2016-12-01

Here, three new lithium salts, lithium difluoro-2-methyl-2-fluoromalonaoborate (LiDFMFMB), lithium difluoro-2-ethyl-2-fluoromalonaoborate (LiDFEFMB), and lithium difluoro-2-propyl-2-fluoro malonaoborate (LiDFPFMB), have been synthesized and evaluated for application in lithium ion batteries. These new salts are soluble in a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (1:2 by wt.) and 1.0 M salt solutions can be easily prepared. The ionic conductivities of these new salts are close to those of LiBF 4 and LiPF 6. Cyclic voltammograms reveal that these new salt based electrolytes can passivate both natural graphite and high voltage spinel LiNi 0.5Mn 1.5O 4 (LNMO) to form effective solidmore » electrolyte interphases (SEIs). In addition, these new salts based electrolytes exhibit good cycling stability with high coulombic efficiencies in both LiNi 0.5Mn 1.5O 4 and graphite based half-cells and full cells.« less

Identification of Primary Transcriptional Regulation of Cell Cycle-Regulated Genes upon DNA Damage

PubMed Central

Zhou, Tong; Chou, Jeff; Mullen, Thomas E.; Elkon, Rani; Zhou, Yingchun; Simpson, Dennis A.; Bushel, Pierre R.; Paules, Richard S.; Lobenhofer, Edward K.; Hurban, Patrick; Kaufmann, William K.

2007-01-01

The changes in global gene expression in response to DNA damage may derive from either direct induction or repression by transcriptional regulation or indirectly by synchronization of cells to specific cell cycle phases, such as G1 or G2. We developed a model that successfully estimated the expression levels of >400 cell cycle-regulated genes in normal human fibroblasts based on the proportions of cells in each phase of the cell cycle. By isolating effects on the gene expression associated with the cell cycle phase redistribution after genotoxin treatment, the direct transcriptional target genes were distinguished from genes for which expression changed secondary to cell synchronization. Application of this model to ionizing radiation (IR)-treated normal human fibroblasts identified 150 of 406 cycle-regulated genes as putative direct transcriptional targets of IR-induced DNA damage. Changes in expression of these genes after IR treatment derived from both direct transcriptional regulation and cell cycle synchronization. PMID:17404513

Longitudinal Course of Depression Scores with and without Insomnia in Non-Depressed Individuals: A 6-Year Follow-Up Longitudinal Study in a Korean Cohort

PubMed Central

Suh, Sooyeon; Kim, Hyun; Yang, Hae-Chung; Cho, Eo Rin; Lee, Seung Ku; Shin, Chol

2013-01-01

Study Objective: This is a population-based longitudinal study that followed insomnia symptoms over a 6-year period in non-depressed individuals. The purpose of the study was to (1) investigate the longitudinal course of depression based on number of insomnia episodes; and (2) describe longitudinal associations between insomnia and depression, and insomnia and suicidal ideation. Design: Population-based longitudinal study. Setting: Community-based sample from the Korean Genome and Epidemiology Study (KoGES). Participants: 1,282 non-depressed individuals (44% male, mean age 52.3 ± 7.14 years) Measurements and Results: This study prospectively assessed insomnia, depression, and suicidal ideation with 4 time points. Individuals were classified into no insomnia (NI), single episode insomnia (SEI), and persistent insomnia (PI; ≥ insomnia at 2+ time points) groups based on number of times insomnia was indicated. Mixed effects modeling indicated that depression scores increased significantly faster in the PI group compared to the NI (P < 0.001) and SEI (P = 0.02) groups. Additionally, the PI group had significantly increased odds of depression as compared to NI or SEI (OR 2.44, P = 0.001) groups, with 18.7% meeting criteria for depression compared to the NI (5.3%) and SEI (11.6%) groups at end point. The PI group also had significantly increased odds of suicidal ideation as compared to NI or SEI (OR 1.86, P = 0.002) groups. Conclusions: Persistent insomnia significantly increases the rate in which depression occurs over time in non-depressed individuals, which ultimately leads to higher risk for depression. Additionally, having persistent insomnia also increased the risk of suicidal ideation. Citation: Suh S; Kim H; Yang HC; Cho ER; Lee SK; Shin C. Longitudinal course of depression scores with and without insomnia in non-depressed individuals: a 6-year follow-up longitudinal study in a Korean cohort. SLEEP 2013;36(3):369-376. PMID:23449814

ARTD1 regulates cyclin E expression and consequently cell-cycle re-entry and G1/S progression in T24 bladder carcinoma cells.

PubMed

Léger, Karolin; Hopp, Ann-Katrin; Fey, Monika; Hottiger, Michael O

2016-08-02

ADP-ribosylation is involved in a variety of biological processes, many of which are chromatin-dependent and linked to important functions during the cell cycle. However, any study on ADP-ribosylation and the cell cycle faces the problem that synchronization with chemical agents or by serum starvation and subsequent growth factor addition already activates ADP-ribosylation by itself. Here, we investigated the functional contribution of ARTD1 in cell cycle re-entry and G1/S cell cycle progression using T24 urinary bladder carcinoma cells, which synchronously re-enter the cell cycle after splitting without any additional stimuli. In synchronized cells, ARTD1 knockdown, but not inhibition of its enzymatic activity, caused specific down-regulation of cyclin E during cell cycle re-entry and G1/S progression through alterations of the chromatin composition and histone acetylation, but not of other E2F-1 target genes. Although Cdk2 formed a functional complex with the residual cyclin E, p27(Kip 1) protein levels increased in G1 upon ARTD1 knockdown most likely due to inappropriate cyclin E-Cdk2-induced phosphorylation-dependent degradation, leading to decelerated G1/S progression. These results provide evidence that ARTD1 regulates cell cycle re-entry and G1/S progression via cyclin E expression and p27(Kip 1) stability independently of its enzymatic activity, uncovering a novel cell cycle regulatory mechanism.

Cell cycle arrest in plants: what distinguishes quiescence, dormancy and differentiated G1?

PubMed

Velappan, Yazhini; Signorelli, Santiago; Considine, Michael J

2017-10-17

Quiescence is a fundamental feature of plant life, which enables plasticity, renewal and fidelity of the somatic cell line. Cellular quiescence is defined by arrest in a particular phase of the cell cycle, typically G1 or G2; however, the regulation of quiescence and proliferation can also be considered across wider scales in space and time. As such, quiescence is a defining feature of plant development and phenology, from meristematic stem cell progenitors to terminally differentiated cells, as well as dormant or suppressed seeds and buds. While the physiology of each of these states differs considerably, each is referred to as 'cell cycle arrest' or 'G1 arrest'. Here the physiology and molecular regulation of (1) meristematic quiescence, (2) dormancy and (3) terminal differentiation (cell cycle exit) are considered in order to determine whether and how the molecular decisions guiding these nuclear states are distinct. A brief overview of the canonical cell cycle regulators is provided, and the genetic and genomic, as well as physiological, evidence is considered regarding two primary questions: (1) Are the canonical cell cycle regulators superior or subordinate in the regulation of quiescence? (2) Are these three modes of quiescence governed by distinct molecular controls? Meristematic quiescence, dormancy and terminal differentiation are each predominantly characterized by G1 arrest but regulated distinctly, at a level largely superior to the canonical cell cycle. Meristematic quiescence is intrinsically linked to non-cell-autonomous regulation of meristem cell identity, and particularly through the influence of ubiquitin-dependent proteolysis, in partnership with reactive oxygen species, abscisic acid and auxin. The regulation of terminal differentiation shares analogous features with meristematic quiescence, albeit with specific activators and a greater role for cytokinin signalling. Dormancy meanwhile appears to be regulated at the level of chromatin accessibility, by Polycomb group-type histone modifications of particular dormancy genes. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

1H,1H,5H-Perfluoropentyl-1,1,2,2-tetrafluoroethylether as a co-solvent for high voltage LiNi1/3Co1/3Mn1/3O2/graphite cells

NASA Astrophysics Data System (ADS)

Wang, Chengyun; Zuo, Xiaoxi; Zhao, Minkai; Xiao, Xin; Yu, Le; Nan, Junmin

2016-03-01

1H,1H,5H-Perfluoropentyl-1,1,2,2-tetrafluoroethylether (F-EAE) mixed with ethylene carbonate (EC), diethyl carbonate (DEC), and lithium hexafluorophosphate (LiPF6) is evaluated as a co-solvent high-potential electrolyte of LiNi1/3Co1/3Mn1/3O2/graphite batteries. Linear sweep voltammetry (LSV) and cyclic voltammetry (CV) indicate that the EC/DEC-based electrolyte with F-EAE possesses a high oxidation potential (>5.2 V vs. Li/Li+) and excellent film-forming characteristics. With 40 wt% F-EAE in the electrolyte, the capacity retention of the LiNi1/3Co1/3Mn1/3O2/graphite pouch cells that are cycled between 3.0 and 4.5 V is significantly improved from 28.8% to 86.8% after 100 cycles. In addition, electrochemical impedance spectroscopy (EIS) of three-electrode pouch cells, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) are used to characterize the effects of F-EAE on the enhanced capacity retention. It is demonstrated that F-EAE facilitates the formation of a stable surface electrolyte interface (SEI) layer with low impedance on the anode and effectively suppresses an increase in the charge-transfer resistance on the cathode. These results suggest that F-EAE can serve as an alternative electrolyte solvent for 4.5 V high voltage rechargeable lithium-ion batteries.

The MADS-box XAANTAL1 increases proliferation at the Arabidopsis root stem-cell niche and participates in transition to differentiation by regulating cell-cycle components

PubMed Central

García-Cruz, Karla V.; García-Ponce, Berenice; Garay-Arroyo, Adriana; Sanchez, María De La Paz; Ugartechea-Chirino, Yamel; Desvoyes, Bénédicte; Pacheco-Escobedo, Mario A.; Tapia-López, Rosalinda; Ransom-Rodríguez, Ivan; Gutierrez, Crisanto; Alvarez-Buylla, Elena R.

2016-01-01

Background Morphogenesis depends on the concerted modulation of cell proliferation and differentiation. Such modulation is dynamically adjusted in response to various external and internal signals via complex transcriptional regulatory networks that mediate between such signals and regulation of cell-cycle and cellular responses (proliferation, growth, differentiation). In plants, which are sessile, the proliferation/differentiation balance is plastically adjusted during their life cycle and transcriptional networks are important in this process. MADS-box genes are key developmental regulators in eukaryotes, but their role in cell proliferation and differentiation modulation in plants remains poorly studied. Methods We characterize the XAL1 loss-of-function xal1-2 allele and overexpression lines using quantitative cellular and cytometry analyses to explore its role in cell cycle, proliferation, stem-cell patterning and transition to differentiation. We used quantitative PCR and cellular markers to explore if XAL1 regulates cell-cycle components and PLETHORA1 (PLT1) gene expression, as well as confocal microscopy to analyse stem-cell niche organization. Key Results We previously showed that XAANTAL1 (XAL1/AGL12) is necessary for Arabidopsis root development as a promoter of cell proliferation in the root apical meristem. Here, we demonstrate that XAL1 positively regulates the expression of PLT1 and important components of the cell cycle: CYCD3;1, CYCA2;3, CYCB1;1, CDKB1;1 and CDT1a. In addition, we show that xal1-2 mutant plants have a premature transition to differentiation with root hairs appearing closer to the root tip, while endoreplication in these plants is partially compromised. Coincidently, the final size of cortex cells in the mutant is shorter than wild-type cells. Finally, XAL1 overexpression-lines corroborate that this transcription factor is able to promote cell proliferation at the stem-cell niche. Conclusion XAL1 seems to be an important component of the networks that modulate cell proliferation/differentiation transition and stem-cell proliferation during Arabidopsis root development; it also regulates several cell-cycle components. PMID:27474508

Measuring Li + inventory losses in LiCoO 2/graphite cells using Raman microscopy

DOE PAGES

Snyder, Chelsea Marie; Apblett, Christopher A.; Grillet, Anne; ...

2016-03-25

Here, the contribution from loss of Li + inventory to capacity fade is described for slow rates (C/10) and long-term cycling (up to 80 cycles). It was found through electrochemical testing and ex-situ Raman analysis that at these slow rates, the entirety of capacity loss up to 80 cycles can be explained by loss of Li + inventory in the cell. The Raman spectrum of LiCoO 2 is sensitive to the state of lithiation and can therefore be leveraged to quantify the state of lithiation for individual particles. With these Raman derived estimates, the lithiation state of the cathode inmore » the discharged state is compared to electrochemical data as a function of cycle number. High correlation is found between Raman quantifications of cycleable lithium and the capacity fade. Additionally, the linear relationship between discharge capacity and cell overpotential suggests that the loss of capacity stems from an impedance rise of the electrodes, which based on Li inventory losses, is caused by SEI formation and repair.« less

Centriole maturation requires regulated Plk1 activity during two consecutive cell cycles.

PubMed

Kong, Dong; Farmer, Veronica; Shukla, Anil; James, Jana; Gruskin, Richard; Kiriyama, Shigeo; Loncarek, Jadranka

2014-09-29

Newly formed centrioles in cycling cells undergo a maturation process that is almost two cell cycles long before they become competent to function as microtubule-organizing centers and basal bodies. As a result, each cell contains three generations of centrioles, only one of which is able to form cilia. It is not known how this long and complex process is regulated. We show that controlled Plk1 activity is required for gradual biochemical and structural maturation of the centrioles and timely appendage assembly. Inhibition of Plk1 impeded accumulation of appendage proteins and appendage formation. Unscheduled Plk1 activity, either in cycling or interphase-arrested cells, accelerated centriole maturation and appendage and cilia formation on the nascent centrioles, erasing the age difference between centrioles in one cell. These findings provide a new understanding of how the centriole cycle is regulated and how proper cilia and centrosome numbers are maintained in the cells.

Centriole maturation requires regulated Plk1 activity during two consecutive cell cycles

PubMed Central

Kong, Dong; Farmer, Veronica; Shukla, Anil; James, Jana; Gruskin, Richard; Kiriyama, Shigeo

2014-01-01

Newly formed centrioles in cycling cells undergo a maturation process that is almost two cell cycles long before they become competent to function as microtubule-organizing centers and basal bodies. As a result, each cell contains three generations of centrioles, only one of which is able to form cilia. It is not known how this long and complex process is regulated. We show that controlled Plk1 activity is required for gradual biochemical and structural maturation of the centrioles and timely appendage assembly. Inhibition of Plk1 impeded accumulation of appendage proteins and appendage formation. Unscheduled Plk1 activity, either in cycling or interphase-arrested cells, accelerated centriole maturation and appendage and cilia formation on the nascent centrioles, erasing the age difference between centrioles in one cell. These findings provide a new understanding of how the centriole cycle is regulated and how proper cilia and centrosome numbers are maintained in the cells. PMID:25246616

Targeting of the Fun30 nucleosome remodeller by the Dpb11 scaffold facilitates cell cycle-regulated DNA end resection

PubMed Central

Bantele, Susanne CS; Ferreira, Pedro; Gritenaite, Dalia; Boos, Dominik; Pfander, Boris

2017-01-01

DNA double strand breaks (DSBs) can be repaired by either recombination-based or direct ligation-based mechanisms. Pathway choice is made at the level of DNA end resection, a nucleolytic processing step, which primes DSBs for repair by recombination. Resection is thus under cell cycle control, but additionally regulated by chromatin and nucleosome remodellers. Here, we show that both layers of control converge in the regulation of resection by the evolutionarily conserved Fun30/SMARCAD1 remodeller. Budding yeast Fun30 and human SMARCAD1 are cell cycle-regulated by interaction with the DSB-localized scaffold protein Dpb11/TOPBP1, respectively. In yeast, this protein assembly additionally comprises the 9-1-1 damage sensor, is involved in localizing Fun30 to damaged chromatin, and thus is required for efficient long-range resection of DSBs. Notably, artificial targeting of Fun30 to DSBs is sufficient to bypass the cell cycle regulation of long-range resection, indicating that chromatin remodelling during resection is underlying DSB repair pathway choice. DOI: http://dx.doi.org/10.7554/eLife.21687.001 PMID:28063255

Socio-economic inequality and HIV in South Africa

PubMed Central

2013-01-01

Background The linkage between the socio-economic inequality and HIV outcomes was analysed using data from a population-based household survey that employed multistage-stratified sampling. The goal is to help refocus attention on how HIV is linked to inequalities. Methods A socio-economic index (SEI) score, derived using Multiple Correspondence Analysis of measures of ownership of durable assets, was used to generate three SEI groups: Low (poorest), Middle, and Upper (no so poor). Distribution of HIV outcomes (i.e. HIV prevalence, access to HIV/AIDS information, level of stigma towards HIV/AIDS, perceived HIV risk and sexual behaviour) across the SEI groups, and other background characteristics was assessed using weighted data. Univariate and multivariate logistic regression was used to assess the covariates of the HIV outcomes across the socio-economic groups. The study sample include 14,384 adults 15 years and older. Results More women (57.5%) than men (42.3%) were found in the poor SEI [P<0.001]. HIV prevalence was highest among the poor (20.8%) followed by those in the middle (15.9%) and those in the upper SEI (4.6%) [P<0.001]. It was also highest among women compared to men (19.7% versus 11.4% respectively) and among black Africans (20.2%) compared to other races [P<0.001]. Individuals in the upper SEI reported higher frequency of HIV testing (59.3%) compared to the low SEI (47.7%) [P< 0.001]. Only 20.5% of those in poor SEI had “good access to HIV/AIDS information” compared to 79.5% in the upper SEI (P<0.001). A higher percentage of the poor had a stigmatizing attitude towards HIV/AIDS (45.6%) compared to those in the upper SEI (34.8%) [P< 0.001]. There was a high personal HIV risk perception among the poor (40.0%) and it declined significantly to 10.9% in the upper SEI. Conclusions Our findings underline the disproportionate burden of HIV disease and HIV fear among the poor and vulnerable in South Africa. The poor are further disadvantaged by lack of access to HIV information and HIV/AIDS services such as testing for HIV infection. There is a compelling urgency for the national HIV/AIDS response to maximizing program focus for the poor particularly women. PMID:24180366

Socio-economic inequality and HIV in South Africa.

PubMed

Wabiri, Njeri; Taffa, Negussie

2013-11-04

The linkage between the socio-economic inequality and HIV outcomes was analysed using data from a population-based household survey that employed multistage-stratified sampling. The goal is to help refocus attention on how HIV is linked to inequalities. A socio-economic index (SEI) score, derived using Multiple Correspondence Analysis of measures of ownership of durable assets, was used to generate three SEI groups: Low (poorest), Middle, and Upper (no so poor). Distribution of HIV outcomes (i.e. HIV prevalence, access to HIV/AIDS information, level of stigma towards HIV/AIDS, perceived HIV risk and sexual behaviour) across the SEI groups, and other background characteristics was assessed using weighted data. Univariate and multivariate logistic regression was used to assess the covariates of the HIV outcomes across the socio-economic groups. The study sample include 14,384 adults 15 years and older. More women (57.5%) than men (42.3%) were found in the poor SEI [P<0.001]. HIV prevalence was highest among the poor (20.8%) followed by those in the middle (15.9%) and those in the upper SEI (4.6%) [P<0.001]. It was also highest among women compared to men (19.7% versus 11.4% respectively) and among black Africans (20.2%) compared to other races [P<0.001]. Individuals in the upper SEI reported higher frequency of HIV testing (59.3%) compared to the low SEI (47.7%) [P< 0.001]. Only 20.5% of those in poor SEI had "good access to HIV/AIDS information" compared to 79.5% in the upper SEI (P<0.001). A higher percentage of the poor had a stigmatizing attitude towards HIV/AIDS (45.6%) compared to those in the upper SEI (34.8%) [P< 0.001]. There was a high personal HIV risk perception among the poor (40.0%) and it declined significantly to 10.9% in the upper SEI. Our findings underline the disproportionate burden of HIV disease and HIV fear among the poor and vulnerable in South Africa. The poor are further disadvantaged by lack of access to HIV information and HIV/AIDS services such as testing for HIV infection. There is a compelling urgency for the national HIV/AIDS response to maximizing program focus for the poor particularly women.

Predicting Software Assurance Using Quality and Reliability Measures

DTIC Science & Technology

2014-12-01

errors are not found in unit testing . The rework effort to correct requirement and design problems in later phases can be as high as 300 to 1,000...Literature 31 Appendix B: Quality Cannot Be Tested In 35 Bibliography 38 CMU/SEI-2014-TN-026 | ii CMU/SEI-2014-TN-026 | iii List of Figures...Removal Densities During Development 10 Figure 8: Quality and Security-Focused Workflow 14 Figure 9: Testing Reliability Results for the Largest Project

A siloxane-incorporated copolymer as an in situ cross-linkable binder for high performance silicon anodes in Li-ion batteries

NASA Astrophysics Data System (ADS)

Jeena, M. T.; Bok, Taesoo; Kim, Si Hoon; Park, Sooham; Kim, Ju-Young; Park, Soojin; Ryu, Ja-Hyoung

2016-04-01

The electrochemical performance of Li-ion batteries (LIBs) can be highly tuned by various factors including the morphology of the anode material, the nature of the electrolyte, the binding material, and the percentage of conducting materials. Binding materials have been of particular interest to researchers over the decades as a means to further improve the cycle durability and columbic efficiency of LIBs. Such approaches include the introduction of different polymeric binders such as poly(acrylic acid) (PAA), carboxymethyl cellulose (CMC), and alginic acid (Alg) into the Si anode of LIBs. To achieve a better efficiency of LIBs, herein, we introduce a novel copolymer, poly(tert-butyl acrylate-co-triethoxyvinylsilane) (TBA-TEVS), as an efficient binder with stable cycle retention and excellent specific capacity. The binder forms a highly interconnected three-dimensional network upon thermal treatment as a result of de-protection of the tert-butyl group and the consequent inter-intra condensation reaction, which minimizes pulverization of the Si nanoparticles. Moreover, the siloxane group is expected to promote the formation of stable solid-electrolyte-interface (SEI) layers. A series of random copolymers were synthesized by varying the molar ratio of tert-butyl acrylate and triethoxyvinylsilane. Twenty-one percent of TEVS in the TBS-TEVS copolymer gave rise to a superior performance as a binder for Si anodes, where the anodes showed a stable specific capacity of 2551 mA h g-1 over hundreds of cycles and an initial columbic efficiency (ICE) of 81.8%.The electrochemical performance of Li-ion batteries (LIBs) can be highly tuned by various factors including the morphology of the anode material, the nature of the electrolyte, the binding material, and the percentage of conducting materials. Binding materials have been of particular interest to researchers over the decades as a means to further improve the cycle durability and columbic efficiency of LIBs. Such approaches include the introduction of different polymeric binders such as poly(acrylic acid) (PAA), carboxymethyl cellulose (CMC), and alginic acid (Alg) into the Si anode of LIBs. To achieve a better efficiency of LIBs, herein, we introduce a novel copolymer, poly(tert-butyl acrylate-co-triethoxyvinylsilane) (TBA-TEVS), as an efficient binder with stable cycle retention and excellent specific capacity. The binder forms a highly interconnected three-dimensional network upon thermal treatment as a result of de-protection of the tert-butyl group and the consequent inter-intra condensation reaction, which minimizes pulverization of the Si nanoparticles. Moreover, the siloxane group is expected to promote the formation of stable solid-electrolyte-interface (SEI) layers. A series of random copolymers were synthesized by varying the molar ratio of tert-butyl acrylate and triethoxyvinylsilane. Twenty-one percent of TEVS in the TBS-TEVS copolymer gave rise to a superior performance as a binder for Si anodes, where the anodes showed a stable specific capacity of 2551 mA h g-1 over hundreds of cycles and an initial columbic efficiency (ICE) of 81.8%. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01559j

Project Interface Requirements Process Including Shuttle Lessons Learned

NASA Technical Reports Server (NTRS)

Bauch, Garland T.

2010-01-01

Most failures occur at interfaces between organizations and hardware. Processing interface requirements at the start of a project life cycle will reduce the likelihood of costly interface changes/failures later. This can be done by adding Interface Control Documents (ICDs) to the Project top level drawing tree, providing technical direction to the Projects for interface requirements, and by funding the interface requirements function directly from the Project Manager's office. The interface requirements function within the Project Systems Engineering and Integration (SE&I) Office would work in-line with the project element design engineers early in the life cycle to enhance communications and negotiate technical issues between the elements. This function would work as the technical arm of the Project Manager to help ensure that the Project cost, schedule, and risk objectives can be met during the Life Cycle. Some ICD Lessons Learned during the Space Shuttle Program (SSP) Life Cycle will include the use of hardware interface photos in the ICD, progressive life cycle design certification by analysis, test, & operations experience, assigning interface design engineers to Element Interface (EI) and Project technical panels, and linking interface design drawings with project build drawings

Gambling Motives: Application of the Reasons for Gambling Questionnaire in an Australian Population Survey.

PubMed

Francis, K L; Dowling, N A; Jackson, A C; Christensen, D R; Wardle, H

2015-09-01

The Reasons for Gambling Questionnaire (RGQ) consist of 15 items forming five factors: enhancement, social, money, recreation and coping. The RGQ was developed for use in the 2010 British Gambling Prevalence Survey (BGPS) and has now been employed in the second Social and Economic Impact Study (SEIS) of Gambling in Tasmania study conducted in 2011 in Australia. Given differences between Britain and Australia in terms of socio-demographic profiles, gambling cultures and attitudes, gambling access and availability, gambling regulation, and rates and patterns of gambling participation, the aims of this study were to analyse the RGQ data from the SEIS to: (1) determine the most commonly endorsed gambling motives in an Australian jurisdiction, (2) explore the factor structure of the RGQ in an Australian sample, and (3) explore how motives for gambling vary among different Australian population sub-groups. A representative sample of the Tasmanian population who had gambled in the previous 12 months (n = 2,796) were administered the RGQ via computer-assisted telephone interviewing. The five most commonly endorsed reasons for gambling were for fun (62%), followed by the chance of winning big money (52%), it being something to do with friends and family (48%), to be sociable (40%), and excitement (38%). A principal component analysis revealed a five-factor structure that is slightly different from that derived in the BGPS: money, regulate internal state, positive feelings, social, and challenge reasons. Finally, gambling motives varied according to socio-demographic factors, number of gambling activities, problem gambling severity, and participation on different gambling activities. Although some of these findings are consistent with those from the BGPS, there are also some slight differences, suggesting that there may be regional-specific variations in gambling motives.

Cell cycle regulation in human embryonic stem cells: links to adaptation to cell culture.

PubMed

Barta, Tomas; Dolezalova, Dasa; Holubcova, Zuzana; Hampl, Ales

2013-03-01

Cell cycle represents not only a tightly orchestrated mechanism of cell replication and cell division but it also plays an important role in regulation of cell fate decision. Particularly in the context of pluripotent stem cells or multipotent progenitor cells, regulation of cell fate decision is of paramount importance. It has been shown that human embryonic stem cells (hESCs) show unique cell cycle characteristics, such as short doubling time due to abbreviated G1 phase; these properties change with the onset of differentiation. This review summarizes the current understanding of cell cycle regulation in hESCs. We discuss cell cycle properties as well as regulatory machinery governing cell cycle progression of undifferentiated hESCs. Additionally, we provide evidence that long-term culture of hESCs is accompanied by changes in cell cycle properties as well as configuration of several cell cycle regulatory molecules.

Carbon dioxide as a green carbon source for the synthesis of carbon cages encapsulating porous silicon as high performance lithium-ion battery anodes.

PubMed

Zhang, Yaguang; Du, Ning; Chen, Yifan; Lin, Yangfan; Jiang, Jinwei; He, Yuanhong; Lei, Yu; Yang, Deren

2018-03-28

Si/C composite is one of the most promising candidate materials for next-generation lithium-ion battery anodes. Herein, we demonstrate the novel structure of carbon cages encapsulating porous Si synthesized by the reaction between magnesium silicide (Mg 2 Si) and carbon dioxide (CO 2 ) and subsequent acid washing. Benefitting from the in situ deposition through magnesiothermic reduction of CO 2 , the carbon cage seals the inner Si completely and shows higher graphitization than that obtained from the decomposition of acetylene. After removing MgO, pores are created, which can accommodate the volume change of the Si anode during the charge/discharge process. As the anode material for lithium-ion batteries, the porous Si/C electrode shows a charge capacity of ∼1124 mA h g -1 after 100 cycles with 86.4% capacity retention at the current density of 0.4 A g -1 . When the current density increases to 1.6 and 3.2 A g -1 , the capacity can still be maintained at ∼860 and ∼460 mA h g -1 , respectively. The prominent cycling and rate performance is contributed by the built-in space for Si expansion, static carbon cages that prevent penetration of electrolyte and stabilize the solid electrolyte interface (SEI) outside, and fast charge transport by the novel structure.

A Reaction-ball-milling-driven Surface Coating Strategy to Suppress Pulverization of Microparticle Si Anodes.

PubMed

Yang, Yaxiong; Qu, Xiaolei; Zhang, Lingchao; Gao, Mingxia; Liu, Yongfeng; Pan, Hongge

2018-06-01

In this work, we report on a novel reaction-ball-milling surface coating strategy to suppress the pulverization of microparticle Si anodes upon lithiation/delithiation. By energetic milling the partially prelithiated microparticle Si in a CO2 atmosphere, a multicomponent amorphous layer composed of SiOx, C, SiC and Li2SiO3 is successfully coated on the surface of Si microparticles. The coating level strongly depends on the milling reaction duration, and the 12-h milled prelithiated Si microparticles (BM12h) under a pressure of 3 bar of CO2 exhibits a good conformal coating with 1.006 g cm3 of tap density. The presence of SiC remarkably enhances the mechanical properties of the SiOx/C coating matrix with an approximately 4-fold increase in the elastic modulus and the hardness values, which effectively alleviates the global volume expansion of the Si microparticles upon lithiation. Simultaneously, the existence of Li2SiO3 insures the Li-ion conductivity of the coating layer. Moreover, the SEI film formed on the electrode surface maintains relatively stable upon cycling due to the remarkably suppressed crack and pulverization of particles. These processes work together to allow the BM12h sample to offer much better cycling stability, as its reversible capacity remains at 1439 mAh g-1 at 100 mA g-1 after 100 cycles, which is nearly 4 times that of the pristine Si microparticles (381 mAh g-1). This work opens up new opportunities for the practical applications of micrometre-scaled Si anode.

On the use of Space Station Freedom in support of the SEI - Life science research

NASA Technical Reports Server (NTRS)

Leath, K.; Volosin, J.; Cookson, S.

1992-01-01

The use of the Space Station Freedom (SSF) for life sciences research is evaluated from the standpoint of requirements for the Space Exploration Initiative (SEI). SEI life sciences research encompasses: (1) biological growth and development in space; (2) life support and environmental health; (3) physiological/psychological factors of extended space travel; and (4) space environmental factors. The platforms required to support useful study in these areas are listed and include ground-based facilities, permanently manned spacecraft, and the Space Shuttle. The SSF is shown to be particularly applicable to the areas of research because its facilities can permit the study of gravitational biology, life-support systems, and crew health. The SSF can serve as an experimental vehicle to derive the required knowledge needed to establish a commitment to manned Mars missions and colonization plans.

Improved Battery Performance of Nanocrystalline Si Anodes Utilized by Radio Frequency (RF) Sputtered Multifunctional Amorphous Si Coating Layers.

PubMed

Ahn, In-Kyoung; Lee, Young-Joo; Na, Sekwon; Lee, So-Yeon; Nam, Dae-Hyun; Lee, Ji-Hoon; Joo, Young-Chang

2018-01-24

Despite the high theoretical specific capacity of Si, commercial Li-ion batteries (LIBs) based on Si are still not feasible because of unsatisfactory cycling stability. Herein, amorphous Si (a-Si)-coated nanocrystalline Si (nc-Si) formed by versatile radio frequency (RF) sputtering systems is proposed as a promising anode material for LIBs. Compared to uncoated nc-Si (retention of 0.6% and Coulombic efficiency (CE) of 79.7%), the a-Si-coated nc-Si (nc-Si@a-Si) anodes show greatly improved cycling retention (C 50th /C first ) of ∼50% and a first CE of 86.6%. From the ex situ investigation with electrochemical impedance spectroscopy (EIS) and cracked morphology during cycling, the a-Si layer was found to be highly effective at protecting the surface of the nc-Si from the formation of solid-state electrolyte interphases (SEI) and to dissipate the mechanical stress upon de/lithiation due to the high fracture toughness.

Designed synergetic effect of electrolyte additives to improve interfacial chemistry of MCMB electrode in propylene carbonate-based electrolyte for enhanced low and room temperature performance.

PubMed

Wotango, Aselefech Sorsa; Su, Wei-Nien; Haregewoin, Atetegeb Meazah; Chen, Hung-Ming; Cheng, Ju-Hsiang; Lin, Ming-Hsien; Wang, Chia-Hsin; Hwang, Bing-Joe

2018-05-09

The performance of lithium ion batteries rapidly falls at lower temperatures due to decreasing conductivity of electrolytes and Solid Electrolyte Interphase (SEI) on graphite anode. Hence, it limits the practical use of lithium ion batteries at sub-zero temperatures and also affects the development of lithium ion batteries for widespread applications. The SEI formed on the graphite surface is very influential in determining the performance of the battery. Herein, a new electrolyte additive, 4-Chloromethyl-1,3,2-dioxathiolane-2-oxide (CMDO), is prepared to improve the properties of commonly used electrolyte constituents - ethylene carbonate (EC), and fluoroethylene carbonate (FEC). The formation of an efficient passivation layer in propylene carbonate (PC) -based electrolyte for MCMB electrode was investigated. The addition of CMDO resulted in a much less irreversible capacity loss and induces thin SEI formation. However, the combination of the three additives played a key role to enhance reversible capacity of MCMB electrode at lower or ambient temperature. The electrochemical measurement analysis showed that the SEI formed from a mixture of the three additives gave better intercalation-deintercalation of lithium ions.

Inhibitor of DNA binding 1 regulates cell cycle progression of endothelial progenitor cells through induction of Wnt2 expression

PubMed Central

Xia, Xi; Yu, Yang; Zhang, Li; Ma, Yang; Wang, Hong

2016-01-01

Endothelial injury is a risk factor for atherosclerosis. Endothelial progenitor cell (EPC) proliferation contributes to vascular injury repair. Overexpression of inhibitor of DNA binding 1 (Id1) significantly promotes EPC proliferation; however, the underlying molecular mechanism remains to be fully elucidated. The present study investigated the role of Id1 in cell cycle regulation of EPCs, which is closely associated with proliferation. Overexpression of Id1 increased the proportion of EPCs in the S/G2M phase and significantly increased cyclin D1 expression levels, while knockdown of Id1 arrested the cell cycle progression of EPCs in the G1 phase and inhibited cyclin D1 expression levels. In addition, it was demonstrated that Id1 upregulated wingless-type mouse mammary tumor virus integration site family member 2 (Wnt2) expression levels and promoted β-catenin accumulation and nuclear translocation. Furthermore, Wnt2 knockdown counteracted the effects of Id1 on cell cycle progression of EPCs. In conclusion, the results of the present study indicate that Id1 promoted Wnt2 expression, which accelerated cell cycle progression from G1 to S phase. This suggests that Id1 may promote cell cycle progression of EPCs, and that Wnt2 may be important in Id1 regulation of the cell cycle of EPCs. PMID:27432753

The MPD thruster program at JPL

NASA Technical Reports Server (NTRS)

Barnett, John; Goodfellow, Keith; Polk, James; Pivirotto, Thomas

1991-01-01

The main topics covered include: (1) the Space Exploration Initiative (SEI) context; (2) critical issues of MPD Thruster design; and (3) the Magnetoplasmadynamic (MPD) Thruster Program at JPL. Under the section on the SEI context the nuclear electric propulsion system and some electric thruster options are addressed. The critical issues of MPD Thruster development deal with the requirements, status, and approach taken. The following areas are covered with respect to the MPD Thruster Program at JPL: (1) the radiation-cooled MPD thruster; (2) the High-Current Cathode Test Facility; (3) thruster component thermal modeling; and (4) alkali metal propellant studies.

Defense in Depth: Foundation for Secure and Resilient IT Enterprises

DTIC Science & Technology

2006-09-01

Gabbard , D., & May, C. (2003). Outsourcing Managed Security Service. http://www.sei.cmu.edu/publications/documents/sims/sim012.html. 296 CMU/SEI...security_matters/2001/2q01/security-2q01.htm. [Allen 03] Allen, J., Gabbard , D., & May, C. Outsourcing Managed Security Service (CMU/SEI-SIM-012

Science and Engineering Indicators 2010. NSB 10-01

ERIC Educational Resources Information Center

Lehming, Rolf F.; Alt, Martha Naomi; Chen, Xianglei; Hall, Leslie; Burton, Lawrence; Burrelli, Joan S.; Kannankutty, Nirmala; Proudfoot, Steven; Regets, Mark C.; Boroush, Mark; Moris, Francisco A.; Wolfe, Raymond M.; Britt, Ronda; Christovich, Leslie; Hill, Derek; Falkenheim, Jaquelina C.; Dunnigan, Paula C.

2010-01-01

"Science and Engineering Indicators" (SEI) is first and foremost a volume of record comprising the major high-quality quantitative data on the U.S. and international science and engineering enterprise. SEI is factual and policy neutral. It does not offer policy options, and it does not make policy recommendations. SEI employs a variety…

Science and Engineering Indicators 2012. NSB 12-01

ERIC Educational Resources Information Center

National Science Foundation, 2012

2012-01-01

Science and Engineering Indicators (SEI) is first and foremost a volume of record comprising the major high-quality quantitative data on the U.S. and international science and engineering enterprise. SEI is factual and policy neutral. It does not offer policy options, and it does not make policy recommendations. SEI employs a variety of…

The B-MYB Transcriptional Network Guides Cell Cycle Progression and Fate Decisions to Sustain Self-Renewal and the Identity of Pluripotent Stem Cells

PubMed Central

Zhan, Ming; Riordon, Daniel R.; Yan, Bin; Tarasova, Yelena S.; Bruweleit, Sarah; Tarasov, Kirill V.; Li, Ronald A.; Wersto, Robert P.; Boheler, Kenneth R.

2012-01-01

Embryonic stem cells (ESCs) are pluripotent and have unlimited self-renewal capacity. Although pluripotency and differentiation have been examined extensively, the mechanisms responsible for self-renewal are poorly understood and are believed to involve an unusual cell cycle, epigenetic regulators and pluripotency-promoting transcription factors. Here we show that B-MYB, a cell cycle regulated phosphoprotein and transcription factor critical to the formation of inner cell mass, is central to the transcriptional and co-regulatory networks that sustain normal cell cycle progression and self-renewal properties of ESCs. Phenotypically, B-MYB is robustly expressed in ESCs and induced pluripotent stem cells (iPSCs), and it is present predominantly in a hypo-phosphorylated state. Knockdown of B-MYB results in functional cell cycle abnormalities that involve S, G2 and M phases, and reduced expression of critical cell cycle regulators like ccnb1 and plk1. By conducting gene expression profiling on control and B-MYB deficient cells, ChIP-chip experiments, and integrative computational analyses, we unraveled a highly complex B-MYB-mediated transcriptional network that guides ESC self-renewal. The network encompasses critical regulators of all cell cycle phases and epigenetic regulators, pluripotency transcription factors, and differentiation determinants. B-MYB along with E2F1 and c-MYC preferentially co-regulate cell cycle target genes. B-MYB also co-targets genes regulated by OCT4, SOX2 and NANOG that are significantly associated with stem cell differentiation, embryonic development, and epigenetic control. Moreover, loss of B-MYB leads to a breakdown of the transcriptional hierarchy present in ESCs. These results coupled with functional studies demonstrate that B-MYB not only controls and accelerates cell cycle progression in ESCs it contributes to fate decisions and maintenance of pluripotent stem cell identity. PMID:22936984

The B-MYB transcriptional network guides cell cycle progression and fate decisions to sustain self-renewal and the identity of pluripotent stem cells.

PubMed

Zhan, Ming; Riordon, Daniel R; Yan, Bin; Tarasova, Yelena S; Bruweleit, Sarah; Tarasov, Kirill V; Li, Ronald A; Wersto, Robert P; Boheler, Kenneth R

2012-01-01

Embryonic stem cells (ESCs) are pluripotent and have unlimited self-renewal capacity. Although pluripotency and differentiation have been examined extensively, the mechanisms responsible for self-renewal are poorly understood and are believed to involve an unusual cell cycle, epigenetic regulators and pluripotency-promoting transcription factors. Here we show that B-MYB, a cell cycle regulated phosphoprotein and transcription factor critical to the formation of inner cell mass, is central to the transcriptional and co-regulatory networks that sustain normal cell cycle progression and self-renewal properties of ESCs. Phenotypically, B-MYB is robustly expressed in ESCs and induced pluripotent stem cells (iPSCs), and it is present predominantly in a hypo-phosphorylated state. Knockdown of B-MYB results in functional cell cycle abnormalities that involve S, G2 and M phases, and reduced expression of critical cell cycle regulators like ccnb1 and plk1. By conducting gene expression profiling on control and B-MYB deficient cells, ChIP-chip experiments, and integrative computational analyses, we unraveled a highly complex B-MYB-mediated transcriptional network that guides ESC self-renewal. The network encompasses critical regulators of all cell cycle phases and epigenetic regulators, pluripotency transcription factors, and differentiation determinants. B-MYB along with E2F1 and c-MYC preferentially co-regulate cell cycle target genes. B-MYB also co-targets genes regulated by OCT4, SOX2 and NANOG that are significantly associated with stem cell differentiation, embryonic development, and epigenetic control. Moreover, loss of B-MYB leads to a breakdown of the transcriptional hierarchy present in ESCs. These results coupled with functional studies demonstrate that B-MYB not only controls and accelerates cell cycle progression in ESCs it contributes to fate decisions and maintenance of pluripotent stem cell identity.

Highly Stable Operation of Lithium Metal Batteries Enabled by the Formation of a Transient High Concentration Electrolyte Layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Jianming; Yan, Pengfei; Mei, Donghai

2016-02-08

Lithium (Li) metal has been extensively investigated as an anode for rechargeable battery applications due to its ultrahigh specific capacity and the lowest redox potential. However, significant challenges including dendrite growth and low Coulombic efficiency are still hindering the practical applications of rechargeable Li metal batteries. Here, we demonstrate that long-term cycling of Li metal batteries can be realized by the formation of a transient high concentration electrolyte layer near the surface of Li metal anode during high rate discharge process. The highly concentrated Li+ ions in this transient layer will immediately solvate with the available solvent molecules and facilitatemore » the formation of a stable and flexible SEI layer composed of a poly(ethylene carbonate) framework integrated with other organic/inorganic lithium salts. This SEI layer largely suppresses the corrosion of Li metal anode by free organic solvents and enables the long-term operation of Li metal batteries. The fundamental findings in this work provide a new direction for the development and operation of Li metal batteries that could be operated at high current densities for a wide range of applications.« less

Lithium dendrite and solid electrolyte interphase investigation using OsO4

NASA Astrophysics Data System (ADS)

Zier, Martin; Scheiba, Frieder; Oswald, Steffen; Thomas, Jürgen; Goers, Dietrich; Scherer, Torsten; Klose, Markus; Ehrenberg, Helmut; Eckert, Jürgen

2014-11-01

Osmium tetroxide (OsO4) staining, commonly used to enhance scattering contrast in electron microscopy of biologic tissue and polymer blends, has been adopted for studies of graphite anodes in lithium-ion batteries. OsO4 shows a coordinated reaction with components of the solid electrolyte interphase (SEI) and lithium dendrites, thereby increasing material contrast for scanning electron microscopy investigations. Utilizing the high affinity of lithium metal to react with osmium tetroxide it was possible to localize even small lithium deposits on graphite electrodes. In spite of their reaction with the OsO4 fume, the lithium dendrite morphology remains almost untouched by the staining procedure, offering information on the dendrite growth process. Correlating the quantity of osmium detected with the amount of residual ("dead") lithium of a discharged electrode, it was possible to obtain a practical measure for lithium plating and stripping efficiencies. EDX mappings allowed for a localization of electrochemically stripped lithium dendrites by their residual stained SEI shells. Cross sections, prepared by focused ion beam (FIB) of cycled graphite electrodes treated with OsO4, revealed important information about deposition and distribution of metallic lithium and the electrolyte reduction layer across the electrode.

Modeling Solvation Structure and Charge Transfer at the Solid Electrolyte Interphase for Lithium-Ion Batteries

NASA Astrophysics Data System (ADS)

Raguette, Lauren Elizabeth

Rechargeable lithium-ion battery technology is providing a revolution in energy storage. However, in order to fully realize this revolution, a better understanding is required of both the bulk properties of battery materials and their interfaces. This work endeavors to use classical molecular dynamics (MD) to investigate the electrochemical interfaces present in lithium-ion batteries to understand the impact of chemical reactions on ion transport. When batteries containing cyclic carbonates and lithium salts are charge cycled, both species can react with the electrodes to form complex solid mixtures at the electrode/electrolyte interface, known as a solid electrolyte interphase (SEI). While decades of experiments have yielded significant insights into the structure of these films and their chemical composition, there remains a lack of connection between the properties of the films and observed ion transport when interfaced with the electrolyte. A combination of MD and enhanced sampling methods will be presented to elucidate the link between the SEI, containing mixtures of dilithium ethylene dicarbonate (Li2EDC), lithium fluoride, and lithium carbonate, and battery performance. By performing extensive free energy calculations, clarity is provided to the impact of ion desolvation on the measured resistance to ion transport within lithium ion batteries.

Solvent decompositions and physical properties of decomposition compounds in Li-ion battery electrolytes studied by DFT calculations and molecular dynamics simulations.

PubMed

Tasaki, Ken

2005-02-24

The density functional theory (DFT) calculations have been performed for the reduction decompositions of solvents widely used in Li-ion secondary battery electrolytes, ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonates (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), including a typical electrolyte additive, vinylene carbonate (VC), at the level of B3LYP/6-311+G(2d,p), both in the gas phase and solution using the polarizable conductor calculation model. In the gas phase, the first electron reduction for the cyclic carbonates and for the linear carbonates is found to be exothermic and endothermic, respectively, while the second electron reduction is endothermic for all the compounds examined. On the contrary, in solution both first and second electron reductions are exothermic for all the compounds. Among the solvents and the additive examined, the likelihood of undergoing the first electron reduction in solution was found in the order of EC > PC > VC > DMC > EMC > DEC with EC being the most likely reduced. VC, on the other hand, is most likely to undergo the second electron reduction among the compounds, in the order of VC > EC > PC. Based on the results, the experimentally demonstrated effectiveness of VC as an excellent electrolyte additive was discussed. The bulk thermodynamic properties of two dilithium alkylene glycol dicarbonates, dilithium ethylene glycol dicarbonate (Li-EDC) and dilithium 1,2-propylene glycol dicarbonate (Li-PDC), as the major component of solid-electrolyte interface (SEI) films were also examined through molecular dynamics (MD) simulations in order to understand the stability of the SEI film. It was found that film produced from a decomposition of EC, modeled by Li-EDC, has a higher density, more cohesive energy, and less solubility to the solvent than the film produced from decomposition of PC, Li-PDC. Further, MD simulations of the interface between the decomposition compound and graphite suggested that Li-EDC has more favorable interactions with the graphite surface than Li-PDC. The difference in the SEI film stability and the behavior of Li-ion battery cycling among the solvents were discussed in terms of the molecular structures.

National Launch System comparative economic analysis

NASA Technical Reports Server (NTRS)

Prince, A.

1992-01-01

Results are presented from an analysis of economic benefits (or losses), in the form of the life cycle cost savings, resulting from the development of the National Launch System (NLS) family of launch vehicles. The analysis was carried out by comparing various NLS-based architectures with the current Shuttle/Titan IV fleet. The basic methodology behind this NLS analysis was to develop a set of annual payload requirements for the Space Station Freedom and LEO, to design launch vehicle architectures around these requirements, and to perform life-cycle cost analyses on all of the architectures. A SEI requirement was included. Launch failure costs were estimated and combined with the relative reliability assumptions to measure the effects of losses. Based on the analysis, a Shuttle/NLS architecture evolving into a pressurized-logistics-carrier/NLS architecture appears to offer the best long-term cost benefit.

SMART: Analyzing the Reuse Potential of Legacy Systems in Service- Oriented Architecture (SOA) Environments

DTIC Science & Technology

2009-04-09

technical faculty for the Master in Software Engineering program at CMU. Grace holds a B.Sc. in Systems Engineering and an Executive MBA from Icesi...University in Cali, Colombia ; and a Master in Software Engineering from Carnegie Mellon University. 3 Version 1.7.3—SEI Webinar—April 2009 © 2009 Carnegie...Resources and Training SMART Report • http://www.sei.cmu.edu/publications/documents/08.reports/08tn008.html Public Courses • Migration of Legacy

Fine Scale Baleen Whale Behavior Observed via Tagging Over Daily Time Scales

DTIC Science & Technology

2012-09-30

right whales and sei whales) and the diel vertical migration behavior of their copepod prey. I hypothesize that (1) right whales track the diel...vertical migration of copepods by feeding near the bottom during the day and at the surface at night, and (2) sei whales are unable to feed on copepods at...depth during the day, and are therefore restricted to feeding on copepods at the surface only. Because copepod diel vertical migration is variable

Fine Scale Baleen Whale Behavior Observed via Tagging Over Daily Time Scales

DTIC Science & Technology

2013-09-30

sei whales) and the diel vertical migration behavior of their copepod prey. I hypothesize that (1) right whales track the diel vertical migration of... copepods by feeding near the bottom during the day and at the surface at night, and (2) sei whales are unable to feed on copepods at depth during the...day, and are therefore restricted to feeding on copepods at the surface only. Because copepod diel vertical migration is variable over time (days to

76 FR 38676 - Gulf of Mexico (GOM), Outer Continental Shelf (OCS), Central Planning Area (CPA), Oil and Gas...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-01

... September 2008. SUPPLEMENTARY INFORMATION: BOEMRE developed the Draft SEIS for CPA Lease Sale 216/222 to consider new information made available since completion of the Multisale EIS and 2009-2012 SEIS, including information concerning the Deepwater Horizon event and spill and new regulatory requirements. This Draft SEIS...

A Study of Arizona's Teachers of English Language Learners

ERIC Educational Resources Information Center

Rios-Aguilar, Cecilia; Gonzalez Canche, Manuel S.; Moll, Luis C.

2012-01-01

Background/Context: In September 2007, the Arizona State Board of Education adopted the Structured English Immersion (SEI) model proposed by the Arizona English Language Learner (ELL) Task Force.During the 2008-2009 academic year, it required all school districts to implement the SEI model.The SEI program, best known as the 4-hour English Language…

Proteomic Analysis of the Cell Cycle of Procylic Form Trypanosoma brucei.

PubMed

Crozier, Thomas W M; Tinti, Michele; Wheeler, Richard J; Ly, Tony; Ferguson, Michael A J; Lamond, Angus I

2018-06-01

We describe a single-step centrifugal elutriation method to produce synchronous Gap1 (G1)-phase procyclic trypanosomes at a scale amenable for proteomic analysis of the cell cycle. Using ten-plex tandem mass tag (TMT) labeling and mass spectrometry (MS)-based proteomics technology, the expression levels of 5325 proteins were quantified across the cell cycle in this parasite. Of these, 384 proteins were classified as cell-cycle regulated and subdivided into nine clusters with distinct temporal regulation. These groups included many known cell cycle regulators in trypanosomes, which validates the approach. In addition, we identify 40 novel cell cycle regulated proteins that are essential for trypanosome survival and thus represent potential future drug targets for the prevention of trypanosomiasis. Through cross-comparison to the TrypTag endogenous tagging microscopy database, we were able to validate the cell-cycle regulated patterns of expression for many of the proteins of unknown function detected in our proteomic analysis. A convenient interface to access and interrogate these data is also presented, providing a useful resource for the scientific community. Data are available via ProteomeXchange with identifier PXD008741 (https://www.ebi.ac.uk/pride/archive/). © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Androgen Receptor-Mediated Growth Suppression of HPr-1AR and PC3-Lenti-AR Prostate Epithelial Cells

PubMed Central

Bolton, Eric C.

2015-01-01

The androgen receptor (AR) mediates the developmental, physiologic, and pathologic effects of androgens including 5α-dihydrotestosterone (DHT). However, the mechanisms whereby AR regulates growth suppression and differentiation of luminal epithelial cells in the prostate gland and proliferation of malignant versions of these cells are not well understood, though they are central to prostate development, homeostasis, and neoplasia. Here, we identify androgen-responsive genes that restrain cell cycle progression and proliferation of human prostate epithelial cell lines (HPr-1AR and PC3-Lenti-AR), and we investigate the mechanisms through which AR regulates their expression. DHT inhibited proliferation of HPr-1AR and PC3-Lenti-AR, and cell cycle analysis revealed a prolonged G1 interval. In the cell cycle, the G1/S-phase transition is initiated by the activity of cyclin D and cyclin-dependent kinase (CDK) complexes, which relieve growth suppression. In HPr-1AR, cyclin D1/2 and CDK4/6 mRNAs were androgen-repressed, whereas CDK inhibitor, CDKN1A, mRNA was androgen-induced. The regulation of these transcripts was AR-dependent, and involved multiple mechanisms. Similar AR-mediated down-regulation of CDK4/6 mRNAs and up-regulation of CDKN1A mRNA occurred in PC3-Lenti-AR. Further, CDK4/6 overexpression suppressed DHT-inhibited cell cycle progression and proliferation of HPr-1AR and PC3-Lenti-AR, whereas CDKN1A overexpression induced cell cycle arrest. We therefore propose that AR-mediated growth suppression of HPr-1AR involves cyclin D1 mRNA decay, transcriptional repression of cyclin D2 and CDK4/6, and transcriptional activation of CDKN1A, which serve to decrease CDK4/6 activity. AR-mediated inhibition of PC3-Lenti-AR proliferation occurs through a similar mechanism, albeit without down-regulation of cyclin D. Our findings provide insight into AR-mediated regulation of prostate epithelial cell proliferation. PMID:26372468

Improved electrochemical performance of spinel LiMn 1.5Ni 0.5O 4 through MgF 2 nano-coating

DOE PAGES

Wu, Qing; Zhang, Xiaoping; Sun, Shuwei; ...

2015-07-08

In this paper, a spinel LiMn 1.5Ni 0.5O 4 (LMNO) cathode material synthesized by a sol–gel method is modified by MgF 2 nano-coating via a wet coating strategy. The results of X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) showed that the MgF 2 nano-coating layers do not physically change the bulk structure of the pristine material. Compared with the pristine compound, the MgF 2-coated LMNO electrodes display enhanced cycling stabilities. Particularly, the 5 wt% MgF 2-coated LMNO demonstrates the best reversibility, with a capacity retention of 89.9% after 100more » cycles, much higher than that of the pristine material, 69.3%. The dQ/dV analysis and apparent Li + diffusion coefficient calculation prove that the kinetic properties are enhanced after MgF 2 surface modification, which partly explains the improved electrochemical performances. Electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR) data confirm that the MgF 2 coating layer helps in suppressing the fast growth of the solid electrolyte interface (SEI) film in repeated cycling, which effectively stabilizes the spinel structure. Finally and additionally, differential scanning calorimetry (DSC) tests show that the MgF 2 nano-coating layer also helps in enhancing the thermal stability of the LMNO cathode.« less

Association between television viewing and self-esteem in children.

PubMed

Tin, Sze Pui Pamela; Ho, Daniel Sai Yin; Mak, Kwok Hang; Wan, Ka Leung; Lam, Tai Hing

2012-07-01

Few studies have examined the effect of excess television (TV) viewing on specific mental health outcomes, such as self-esteem. We explored the cross-sectional association between TV viewing hours and self-esteem in young children. A total of 70,210 primary 4 (US grade 4) participants of the Department of Health Student Health Service, Hong Kong, in 1998-2000 reported TV viewing hours in a standardized questionnaire. Self-esteem was assessed using the Culture-Free Self-Esteem Inventories for Children (SEI) with 4 subscales. Multivariate linear regression yielded beta coefficients (β) for SEI subscale scores by TV hours, adjusting for age, sex, body mass index, lifestyle characteristics, and highest parental education and occupational status. Only 10.9% of children watched >4 hours per day, while 45.3% watched TV for 1 to ≤2 hours per day. Compared with children who watched <1 hour of TV per day, those who watched a moderate amount (1 to ≤2 hours/day) had higher (more favorable) SEI scores in the General (β = 0.09; 95% confidence interval = 0.02-0.16), Social (0.05; 0.01-0.09), and Parent-Related (0.04; 0.00-0.08) subscales but lower scores in the Academic subscale (-0.06; -0.09 to -0.02). Children who watched >2 hours of TV per day had lower SEI scores than those who watched <1 hour per day in all 4 subscales. An inverted J-shaped relation was observed between TV viewing hours and self-esteem among young children. The development of self-esteem among children who report little or excessive TV viewing should be further studied.

Live-cell monitoring of periodic gene expression in synchronous human cells identifies Forkhead genes involved in cell cycle control

PubMed Central

Grant, Gavin D.; Gamsby, Joshua; Martyanov, Viktor; Brooks, Lionel; George, Lacy K.; Mahoney, J. Matthew; Loros, Jennifer J.; Dunlap, Jay C.; Whitfield, Michael L.

2012-01-01

We developed a system to monitor periodic luciferase activity from cell cycle–regulated promoters in synchronous cells. Reporters were driven by a minimal human E2F1 promoter with peak expression in G1/S or a basal promoter with six Forkhead DNA-binding sites with peak expression at G2/M. After cell cycle synchronization, luciferase activity was measured in live cells at 10-min intervals across three to four synchronous cell cycles, allowing unprecedented resolution of cell cycle–regulated gene expression. We used this assay to screen Forkhead transcription factors for control of periodic gene expression. We confirmed a role for FOXM1 and identified two novel cell cycle regulators, FOXJ3 and FOXK1. Knockdown of FOXJ3 and FOXK1 eliminated cell cycle–dependent oscillations and resulted in decreased cell proliferation rates. Analysis of genes regulated by FOXJ3 and FOXK1 showed that FOXJ3 may regulate a network of zinc finger proteins and that FOXK1 binds to the promoter and regulates DHFR, TYMS, GSDMD, and the E2F binding partner TFDP1. Chromatin immunoprecipitation followed by high-throughput sequencing analysis identified 4329 genomic loci bound by FOXK1, 83% of which contained a FOXK1-binding motif. We verified that a subset of these loci are activated by wild-type FOXK1 but not by a FOXK1 (H355A) DNA-binding mutant. PMID:22740631

Identification and characterization of the BmCyclin L1-BmCDK11A/B complex in relation to cell cycle regulation.

PubMed

Liu, Tai-Hang; Wu, Yun-Fei; Dong, Xiao-Long; Pan, Cai-Xia; Du, Guo-Yu; Yang, Ji-Gui; Wang, Wei; Bao, Xi-Yan; Chen, Peng; Pan, Min-Hui; Lu, Cheng

2017-05-03

Cyclin proteins are the key regulatory and activity partner of cyclin-dependent kinases (CDKs), which play pivotal regulatory roles in cell cycle progression. In the present study, we identified a Cyclin L1 and 2 CDK11 2 CDK11 splice variants, CDK11A and CDK11B, from silkworm, Bombyx mori. We determined that both Cyclin L1 and CDK11A/B are nuclear proteins, and further investigations were conducted to elucidate their spatiofunctional features. Cyclin L1 forms a complex with CDK11A/B and were co-localized to the nucleus. Moreover, the dimerization of CDK11A and CDK11B and the effects of Cyclin L1 and CDK11A/B on cell cycle regulation were also investigated. Using overexpression or RNA interference experiments, we demonstrated that the abnormal expression of Cyclin L1 and CDK11A/B leads to cell cycle arrest and cell proliferation suppression. Together, these findings indicate that CDK11A/B interacts with Cyclin L1 to regulate the cell cycle.

The Temporal Regulation of S Phase Proteins During G1

PubMed Central

Grant, Gavin D.; Cook, Jeanette G.

2018-01-01

Successful DNA replication requires intimate coordination with cell cycle progression. Prior to DNA replication initiation in S phase, a series of essential preparatory events in G1 phase ensures timely, complete, and precise genome duplication. Among the essential molecular processes are regulated transcriptional upregulation of genes that encode replication proteins, appropriate post-transcriptional control of replication factor abundance and activity, and the assembly of DNA-loaded protein complexes to license replication origins. In this chapter we describe these critical G1 events necessary for DNA replication and their regulation in the context of both cell cycle entry and cell cycle progression. PMID:29357066

Mechanisms involved in regulating DNA replication origins during the cell cycle and in response to DNA damage.

PubMed Central

Early, Anne; Drury, Lucy S; Diffley, John F X

2004-01-01

Replication origins in eukaryotic cells never fire more than once in a given S phase. Here, we summarize the role of cyclin-dependent kinases in limiting DNA replication origin usage to once per cell cycle in the budding yeast Saccharomyces cerevisiae. We have examined the role of different cyclins in the phosphorylation and regulation of several replication/regulatory factors including Cdc6, Sic1, ORC and DNA polymerase alpha-primase. In addition to being regulated by the cell cycle machinery, replication origins are also regulated by the genome integrity checkpoint kinases, Mec1 and Rad53. In response to DNA damage or drugs which interfere with the progression of replication forks, the activation of late-firing replication origins is inhibited. There is evidence indicating that the temporal programme of origin firing depends upon the local histone acetylation state. We have attempted to test the possibility that checkpoint regulation of late-origin firing operates through the regulation of the acetylation state. We found that overexpression of the essential histone acetylase, Esal, cannot override checkpoint regulation of origin firing. We have also constructed a temperature-sensitive esa1 mutant. This mutant is unable to resume cell cycle progression after alpha-factor arrest. This can be overcome by overexpression of the G1 cyclin, Cln2, revealing a novel role for Esal in regulating Start. PMID:15065654

DNA replication checkpoint promotes G1-S transcription by inactivating the MBF repressor Nrm1

PubMed Central

de Bruin, R. A. M.; Kalashnikova, T. I.; Aslanian, A.; Wohlschlegel, J.; Chahwan, C.; Yates, J. R.; Russell, P.; Wittenberg, C.

2008-01-01

The cell cycle transcriptional program imposes order on events of the cell-cycle and is a target for signals that regulate cell-cycle progression, including checkpoints required to maintain genome integrity. Neither the mechanism nor functional significance of checkpoint regulation of the cell-cycle transcription program are established. We show that Nrm1, an MBF-specific transcriptional repressor acting at the transition from G1 to S phase of the cell cycle, is at the nexus between the cell cycle transcriptional program and the DNA replication checkpoint in fission yeast. Phosphorylation of Nrm1 by the Cds1 (Chk2) checkpoint protein kinase, which is activated in response to DNA replication stress, promotes its dissociation from the MBF transcription factor. This leads to the expression of genes encoding components that function in DNA replication and repair pathways important for cell survival in response to arrested DNA replication. PMID:18682565

Porcine epidemic diarrhea virus through p53-dependent pathway causes cell cycle arrest in the G0/G1 phase.

PubMed

Sun, Pei; Wu, Haoyang; Huang, Jiali; Xu, Ying; Yang, Feng; Zhang, Qi; Xu, Xingang

2018-05-22

Porcine epidemic diarrhea virus (PEDV), an enteropathogenic Alphacoronavirus, has caused enormous economic losses in the swine industry. p53 protein exists in a wide variety of animal cells, which is involved in cell cycle regulation, apoptosis, cell differentiation and other biological functions. In this study, we investigated the effects of PEDV infection on the cell cycle of Vero cells and p53 activation. The results demonstrated that PEDV infection induces cell cycle arrest at G0/G1 phase in Vero cells, while UV-inactivated PEDV does not cause cell cycle arrest. PEDV infection up-regulates the levels of p21, cdc2, cdk2, cdk4, Cyclin A protein and down-regulates Cyclin E protein. Further research results showed that inhibition of p53 signaling pathway can reverse the cell cycle arrest in G0/G1 phase induced by PEDV infection and cancel out the up-regulation of p21 and corresponding Cyclin/cdk mentioned above. In addition, PEDV infection of the cells synchronized in various stages of cell cycle showed that viral subgenomic RNA and virus titer were higher in the cells released from G0/G1 phase synchronized cells than that in the cells released from the G1/S phase and G2/M phase synchronized or asynchronous cells after 18 h p.i.. This is the first report to demonstrate that the p53-dependent pathway plays an important role in PEDV induced cell cycle arrest and beneficially contributes to viral infection. Copyright © 2018 Elsevier B.V. All rights reserved.

The MADS-box XAANTAL1 increases proliferation at the Arabidopsis root stem-cell niche and participates in transition to differentiation by regulating cell-cycle components.

PubMed

García-Cruz, Karla V; García-Ponce, Berenice; Garay-Arroyo, Adriana; Sanchez, María De La Paz; Ugartechea-Chirino, Yamel; Desvoyes, Bénédicte; Pacheco-Escobedo, Mario A; Tapia-López, Rosalinda; Ransom-Rodríguez, Ivan; Gutierrez, Crisanto; Alvarez-Buylla, Elena R

2016-07-29

Morphogenesis depends on the concerted modulation of cell proliferation and differentiation. Such modulation is dynamically adjusted in response to various external and internal signals via complex transcriptional regulatory networks that mediate between such signals and regulation of cell-cycle and cellular responses (proliferation, growth, differentiation). In plants, which are sessile, the proliferation/differentiation balance is plastically adjusted during their life cycle and transcriptional networks are important in this process. MADS-box genes are key developmental regulators in eukaryotes, but their role in cell proliferation and differentiation modulation in plants remains poorly studied. We characterize the XAL1 loss-of-function xal1-2 allele and overexpression lines using quantitative cellular and cytometry analyses to explore its role in cell cycle, proliferation, stem-cell patterning and transition to differentiation. We used quantitative PCR and cellular markers to explore if XAL1 regulates cell-cycle components and PLETHORA1 (PLT1) gene expression, as well as confocal microscopy to analyse stem-cell niche organization. We previously showed that XAANTAL1 (XAL1/AGL12) is necessary for Arabidopsis root development as a promoter of cell proliferation in the root apical meristem. Here, we demonstrate that XAL1 positively regulates the expression of PLT1 and important components of the cell cycle: CYCD3;1, CYCA2;3, CYCB1;1, CDKB1;1 and CDT1a In addition, we show that xal1-2 mutant plants have a premature transition to differentiation with root hairs appearing closer to the root tip, while endoreplication in these plants is partially compromised. Coincidently, the final size of cortex cells in the mutant is shorter than wild-type cells. Finally, XAL1 overexpression-lines corroborate that this transcription factor is able to promote cell proliferation at the stem-cell niche. XAL1 seems to be an important component of the networks that modulate cell proliferation/differentiation transition and stem-cell proliferation during Arabidopsis root development; it also regulates several cell-cycle components. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Stable, fast and high-energy-density LiCoO2 cathode at high operation voltage enabled by glassy B2O3 modification

NASA Astrophysics Data System (ADS)

Zhou, Aijun; Wang, Weihang; Liu, Qin; Wang, Yi; Yao, Xu; Qing, Fangzhu; Li, Enzhu; Yang, Tingting; Zhang, Long; Li, Jingze

2017-09-01

In this work, commercial LiCoO2 is modified with a glassy B2O3 by solution mixing with H3BO3 followed by post-calcination in order to enhance its high-voltage electrochemical performance. The glassy B2O3 coating/additive is believed to serve as an effective physiochemical buffer and protection between LiCoO2 and liquid electrolyte, which can suppress the high-voltage induced electrolyte decomposition and active material dissolution. During the early cycling and due to the electrochemical force, the as-coated B2O3 glasses which have 3D open frameworks tend to accommodate some mobile Li+ and form a more chemically-resistant and ion-conductive lithium boron oxide (LBO) interphase as a major component of the solid electrolyte interphase (SEI), which consequently enables much easier Li+ diffusion/transfer at the solid-liquid interfaces upon further cycling. Due to the synergetic effects of B2O3 coating/modification, the high-voltage capacity and energy density of the B2O3-modified LiCoO2 cathode are promisingly improved by 35% and 30% after 100 cycles at 1 C within 3.0-4.5 V vs. Li/Li+. Meanwhile, the high-rate performance of the B2O3-modified electrode is even more greatly improved, showing a capacity of 105 mAh g-1 at 10 C while the bare electrode has dropped to no more than 30 mAh g-1 under this rate condition.

Circadian clock regulation of the cell cycle in the zebrafish intestine.

PubMed

Peyric, Elodie; Moore, Helen A; Whitmore, David

2013-01-01

The circadian clock controls cell proliferation in a number of healthy tissues where cell renewal and regeneration are critical for normal physiological function. The intestine is an organ that typically undergoes regular cycles of cell division, differentiation and apoptosis as part of its role in digestion and nutrient absorption. The aim of this study was to explore circadian clock regulation of cell proliferation and cell cycle gene expression in the zebrafish intestine. Here we show that the zebrafish gut contains a directly light-entrainable circadian pacemaker, which regulates the daily timing of mitosis. Furthermore, this intestinal clock controls the expression of key cell cycle regulators, such as cdc2, wee1, p21, PCNA and cdk2, but only weakly influences cyclin B1, cyclin B2 and cyclin E1 expression. Interestingly, food deprivation has little impact on circadian clock function in the gut, but dramatically reduces cell proliferation, as well as cell cycle gene expression in this tissue. Timed feeding under constant dark conditions is able to drive rhythmic expression not only of circadian clock genes, but also of several cell cycle genes, suggesting that food can entrain the clock, as well as the cell cycle in the intestine. Rather surprisingly, we found that timed feeding is critical for high amplitude rhythms in cell cycle gene expression, even when zebrafish are maintained on a light-dark cycle. Together these results suggest that the intestinal clock integrates multiple rhythmic cues, including light and food, to function optimally.

Circadian Clock Regulation of the Cell Cycle in the Zebrafish Intestine

PubMed Central

Peyric, Elodie; Moore, Helen A.; Whitmore, David

2013-01-01

The circadian clock controls cell proliferation in a number of healthy tissues where cell renewal and regeneration are critical for normal physiological function. The intestine is an organ that typically undergoes regular cycles of cell division, differentiation and apoptosis as part of its role in digestion and nutrient absorption. The aim of this study was to explore circadian clock regulation of cell proliferation and cell cycle gene expression in the zebrafish intestine. Here we show that the zebrafish gut contains a directly light-entrainable circadian pacemaker, which regulates the daily timing of mitosis. Furthermore, this intestinal clock controls the expression of key cell cycle regulators, such as cdc2, wee1, p21, PCNA and cdk2, but only weakly influences cyclin B1, cyclin B2 and cyclin E1 expression. Interestingly, food deprivation has little impact on circadian clock function in the gut, but dramatically reduces cell proliferation, as well as cell cycle gene expression in this tissue. Timed feeding under constant dark conditions is able to drive rhythmic expression not only of circadian clock genes, but also of several cell cycle genes, suggesting that food can entrain the clock, as well as the cell cycle in the intestine. Rather surprisingly, we found that timed feeding is critical for high amplitude rhythms in cell cycle gene expression, even when zebrafish are maintained on a light-dark cycle. Together these results suggest that the intestinal clock integrates multiple rhythmic cues, including light and food, to function optimally. PMID:24013905

Operando Measurement of Solid Electrolyte Interphase Formation at Working Electrode of Li-Ion Battery by Time-Slicing Neutron Reflectometry.

PubMed

Kawaura, Hiroyuki; Harada, Masashi; Kondo, Yasuhito; Kondo, Hiroki; Suganuma, Yoshitake; Takahashi, Naoko; Sugiyama, Jun; Seno, Yoshiki; Yamada, Norifumi L

2016-04-20

We report the first operando measurement of solid electrolyte interphase (SEI) formation at an electrode using in situ neutron reflectometry. The results revealed the growth of the SEI and intercalation of ions during the charge reaction. Furthermore, we propose a way of evaluating the charge used for the SEI formation.

Systems engineering and integration and management for manned space flight programs

NASA Technical Reports Server (NTRS)

Morris, Owen

1993-01-01

This paper discusses the history of SE&I management of the overall program architecture, organizational structure and the relationship of SE&I to other program organizational elements. A brief discussion of the method of executing the SE&I process, a summary of some of the major lessons learned, and identification of things that have proven successful are included.

Systems engineering and integration and management for manned space flight programs

NASA Astrophysics Data System (ADS)

Morris, Owen

This paper discusses the history of SE&I management of the overall program architecture, organizational structure and the relationship of SE&I to other program organizational elements. A brief discussion of the method of executing the SE&I process, a summary of some of the major lessons learned, and identification of things that have proven successful are included.

Urea cycle regulation by mitochondrial sirtuin, SIRT5.

PubMed

Nakagawa, Takashi; Guarente, Leonard

2009-06-29

Mammalian sirtuins have diverse roles in aging, metabolism and disease. Recently we reported a new function for SIRT5 in urea cycle regulation. Our study uncovered that SIRT5 localized to mitochondria matrix and deacetylates carbamoyl phosphate synthetase 1 (CPS1), an enzyme which is the first and rate-limiting step of urea cycle. Deacetylation of CPS1 by SIRT5 resulted in activation of CPS1 enzymatic activity. Indeed, SIRT5-deficient mice failed to up-regulate CPS1 activity and showed hyper ammonemia during fasting. Similar effects are also observed on high protein diet or calorie restriction. These data indicate SIRT5 also has an emerging role in the metabolic adaptation to fasting, high protein diet and calorie restriction.

Sonic hedgehog controls growth of external genitalia by regulating cell cycle kinetics

PubMed Central

Seifert, Ashley W.; Zheng, Zhengui; Ormerod, Brandi K.; Cohn, Martin J.

2010-01-01

During embryonic development, cells are instructed which position to occupy, they interpret these cues as differentiation programmes, and expand these patterns by growth. Sonic hedgehog (Shh) specifies positional identity in many organs; however, its role in growth is not well understood. In this study, we show that inactivation of Shh in external genitalia extends the cell cycle from 8.5 to 14.4 h, and genital growth is reduced by ∼75%. Transient Shh signalling establishes pattern in the genital tubercle; however, transcriptional levels of G1 cell cycle regulators are reduced. Consequently, G1 length is extended, leading to fewer progenitor cells entering S-phase. Cell cycle genes responded similarly to Shh inactivation in genitalia and limbs, suggesting that Shh may regulate growth by similar mechanisms in different organ systems. The finding that Shh regulates cell number by controlling the length of specific cell cycle phases identifies a novel mechanism by which Shh elaborates pattern during appendage development. PMID:20975695

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bae, Sijeong; Kwon, Hwang; Yoon, Hyemin

The sine oculis homeobox 1 (SIX1) is a member of the Six gene family. SIX1 is involved in tissue development by regulating proliferation, apoptosis, and differentiation. However, function of SIX1 in the uterus remains unknown. Here, we found that Six1 expression is regulated along the estrous cycle in mouse uterus. Six1 expression was significantly increased at estrus stage and decreased at the rest of stages. SIX1 is detected in the luminal and glandular epithelium of uterine endometrium at the estrus stage. Estrogen injection increased Six1 expression in the ovariectomized mouse uterus, whereas progesterone had no effect on its expression. Estrogenmore » receptor antagonist inhibited estrogen-induced Six1 expression. Our findings imply that SIX1 may play a role as an important regulator to orchestrate the dynamic of uterine endometrium in response to estrogen level during the estrous cycle. These results will give us a better understanding of uterine biology. - Highlights: • Six1 expression is regulated during the estrous cycle in mouse uterus. • Six1 is highly expressed at the estrus stage of estrous cycle. • SIX1 is detected in luminal/glandular epithelium of the uterus at the estrus stage. • Estrogen stimulates Six1 expression in an estrogen receptor-dependent manner.« less

Artificially-built solid electrolyte interphase via surface-bonded vinylene carbonate derivative on graphite by molecular layer deposition

NASA Astrophysics Data System (ADS)

Chae, Seulki; Lee, Jeong Beom; Lee, Jae Gil; Lee, Tae-jin; Soon, Jiyong; Ryu, Ji Heon; Lee, Jin Seok; Oh, Seung M.

2017-12-01

Vinylene carbonate (VC) is attached in a ring-opened form on a graphite surface by molecular layer deposition (MLD) method, and its role as a solid electrolyte interphase (SEI) former is studied. When VC is added into the electrolyte solution of a graphite/LiNi0.5Mn1.5O4 (LNMO) full-cell, it is reductively decomposed to form an effective SEI on the graphite electrode. However, VC in the electrolyte solution has serious adverse effects due to its poor stability against electrochemical oxidation on the LNMO positive electrode. A excessive acid generation as a result of VC oxidation is observed, causing metal dissolution from the LNMO electrode. The dissolved metal ions are plated on the graphite electrode to destroy the SEI layer, eventually causing serious capacity fading and poor Coulombic efficiency. The VC derivative on the graphite surface also forms an effective SEI layer on the graphite negative electrode via reductive decomposition. The detrimental effects on the LNMO positive electrode, however, can be avoided because the bonded VC derivative on the graphite surface cannot move to the LNMO electrode. Consequently, the graphite/LNMO full-cell fabricated with the VC-attached graphite outperforms the cells without VC or with VC in the electrolyte, in terms of Coulombic efficiency and capacity retention.

Constellation Program Life-cycle Cost Analysis Model (LCAM)

NASA Technical Reports Server (NTRS)

Prince, Andy; Rose, Heidi; Wood, James

2008-01-01

The Constellation Program (CxP) is NASA's effort to replace the Space Shuttle, return humans to the moon, and prepare for a human mission to Mars. The major elements of the Constellation Lunar sortie design reference mission architecture are shown. Unlike the Apollo Program of the 1960's, affordability is a major concern of United States policy makers and NASA management. To measure Constellation affordability, a total ownership cost life-cycle parametric cost estimating capability is required. This capability is being developed by the Constellation Systems Engineering and Integration (SE&I) Directorate, and is called the Lifecycle Cost Analysis Model (LCAM). The requirements for LCAM are based on the need to have a parametric estimating capability in order to do top-level program analysis, evaluate design alternatives, and explore options for future systems. By estimating the total cost of ownership within the context of the planned Constellation budget, LCAM can provide Program and NASA management with the cost data necessary to identify the most affordable alternatives. LCAM is also a key component of the Integrated Program Model (IPM), an SE&I developed capability that combines parametric sizing tools with cost, schedule, and risk models to perform program analysis. LCAM is used in the generation of cost estimates for system level trades and analyses. It draws upon the legacy of previous architecture level cost models, such as the Exploration Systems Mission Directorate (ESMD) Architecture Cost Model (ARCOM) developed for Simulation Based Acquisition (SBA), and ATLAS. LCAM is used to support requirements and design trade studies by calculating changes in cost relative to a baseline option cost. Estimated costs are generally low fidelity to accommodate available input data and available cost estimating relationships (CERs). LCAM is capable of interfacing with the Integrated Program Model to provide the cost estimating capability for that suite of tools.

The Application of Poly(3-hexylthiophene-2,5-diyl) as a Protective Coating for High Rate Cathode Materials

DOE PAGES

Lai, Chun-Han; Ashby, David S.; Lin, Terri C.; ...

2018-03-01

Poly (3-hexylthiophene-2,5-diyl) (P3HT), a conducting polymer studied extensively for its optoelectronic devices, offers a number of advantageous properties when used as a conductive binder for lithium-ion battery cathode materials. By mixing with carbon nanotubes (CNT), P3HTCNT serves as a surface coating for the cathode material LiNi 0.8Co 0.15Al 0.05O 2 (NCA). Oxidation of the P3HT enables high electronic and ionic conductivity to be achieved over the potential range where the NCA is electrochemically active. In addition to the conductivity benefits from electrochemical doping, the P3HT-CNT coating suppresses electrolyte breakdown, thus inhibiting growth of the solid electrolyte interphase (SEI) layer andmore » preventing intergranular cracking in the NCA particles. In conclusion, The use of the P3HT-CNT binder system leads to improved cycling for NCA at high power density with capacities of 80 mAh g -1 obtained after 1000 cycles at 16C, a value that is 4 times greater than what is achieved in the control electrode.« less

The Application of Poly(3-hexylthiophene-2,5-diyl) as a Protective Coating for High Rate Cathode Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lai, Chun-Han; Ashby, David S.; Lin, Terri C.

Poly (3-hexylthiophene-2,5-diyl) (P3HT), a conducting polymer studied extensively for its optoelectronic devices, offers a number of advantageous properties when used as a conductive binder for lithium-ion battery cathode materials. By mixing with carbon nanotubes (CNT), P3HTCNT serves as a surface coating for the cathode material LiNi 0.8Co 0.15Al 0.05O 2 (NCA). Oxidation of the P3HT enables high electronic and ionic conductivity to be achieved over the potential range where the NCA is electrochemically active. In addition to the conductivity benefits from electrochemical doping, the P3HT-CNT coating suppresses electrolyte breakdown, thus inhibiting growth of the solid electrolyte interphase (SEI) layer andmore » preventing intergranular cracking in the NCA particles. In conclusion, The use of the P3HT-CNT binder system leads to improved cycling for NCA at high power density with capacities of 80 mAh g -1 obtained after 1000 cycles at 16C, a value that is 4 times greater than what is achieved in the control electrode.« less

E2F1-mediated upregulation of p19INK4d determines its periodic expression during cell cycle and regulates cellular proliferation.

PubMed

Carcagno, Abel L; Marazita, Mariela C; Ogara, María F; Ceruti, Julieta M; Sonzogni, Silvina V; Scassa, María E; Giono, Luciana E; Cánepa, Eduardo T

2011-01-01

A central aspect of development and disease is the control of cell proliferation through regulation of the mitotic cycle. Cell cycle progression and directionality requires an appropriate balance of positive and negative regulators whose expression must fluctuate in a coordinated manner. p19INK4d, a member of the INK4 family of CDK inhibitors, has a unique feature that distinguishes it from the remaining INK4 and makes it a likely candidate for contributing to the directionality of the cell cycle. p19INK4d mRNA and protein levels accumulate periodically during the cell cycle under normal conditions, a feature reminiscent of cyclins. In this paper, we demonstrate that p19INK4d is transcriptionally regulated by E2F1 through two response elements present in the p19INK4d promoter. Ablation of this regulation reduced p19 levels and restricted its expression during the cell cycle, reflecting the contribution of a transcriptional effect of E2F1 on p19 periodicity. The induction of p19INK4d is delayed during the cell cycle compared to that of cyclin E, temporally separating the induction of these proliferative and antiproliferative target genes. Specific inhibition of the E2F1-p19INK4d pathway using triplex-forming oligonucleotides that block E2F1 binding on p19 promoter, stimulated cell proliferation and increased the fraction of cells in S phase. The results described here support a model of normal cell cycle progression in which, following phosphorylation of pRb, free E2F induces cyclin E, among other target genes. Once cyclinE/CDK2 takes over as the cell cycle driving kinase activity, the induction of p19 mediated by E2F1 leads to inhibition of the CDK4,6-containing complexes, bringing the G1 phase to an end. This regulatory mechanism constitutes a new negative feedback loop that terminates the G1 phase proliferative signal, contributing to the proper coordination of the cell cycle and provides an additional mechanism to limit E2F activity.

E2F1-Mediated Upregulation of p19INK4d Determines Its Periodic Expression during Cell Cycle and Regulates Cellular Proliferation

PubMed Central

Carcagno, Abel L.; Marazita, Mariela C.; Ogara, María F.; Ceruti, Julieta M.; Sonzogni, Silvina V.; Scassa, María E.; Giono, Luciana E.; Cánepa, Eduardo T.

2011-01-01

Background A central aspect of development and disease is the control of cell proliferation through regulation of the mitotic cycle. Cell cycle progression and directionality requires an appropriate balance of positive and negative regulators whose expression must fluctuate in a coordinated manner. p19INK4d, a member of the INK4 family of CDK inhibitors, has a unique feature that distinguishes it from the remaining INK4 and makes it a likely candidate for contributing to the directionality of the cell cycle. p19INK4d mRNA and protein levels accumulate periodically during the cell cycle under normal conditions, a feature reminiscent of cyclins. Methodology/Principal Findings In this paper, we demonstrate that p19INK4d is transcriptionally regulated by E2F1 through two response elements present in the p19INK4d promoter. Ablation of this regulation reduced p19 levels and restricted its expression during the cell cycle, reflecting the contribution of a transcriptional effect of E2F1 on p19 periodicity. The induction of p19INK4d is delayed during the cell cycle compared to that of cyclin E, temporally separating the induction of these proliferative and antiproliferative target genes. Specific inhibition of the E2F1-p19INK4d pathway using triplex-forming oligonucleotides that block E2F1 binding on p19 promoter, stimulated cell proliferation and increased the fraction of cells in S phase. Conclusions/Significance The results described here support a model of normal cell cycle progression in which, following phosphorylation of pRb, free E2F induces cyclin E, among other target genes. Once cyclinE/CDK2 takes over as the cell cycle driving kinase activity, the induction of p19 mediated by E2F1 leads to inhibition of the CDK4,6-containing complexes, bringing the G1 phase to an end. This regulatory mechanism constitutes a new negative feedback loop that terminates the G1 phase proliferative signal, contributing to the proper coordination of the cell cycle and provides an additional mechanism to limit E2F activity. PMID:21765927

Advancing Cyber Intelligence Practices Through the SEI’s Consortium

DTIC Science & Technology

2015-01-27

blogsjsocial media Extracurricular Activities Vu lnerabilities from these individuals roles with non-target entities-non-profits, activist groups, or...information to identify, track, and predict cyber capabilities, intentions, and activities to offer courses of action that enhance decision making 7 SEI...8 SEI Webinar Series January 27, 2015 © 2015 Carnegie Mellon University Offerings Steering Committee: Guide Consortium activities and plan for

Proliferation of Shadow Education Institutions (SEI's) in the Philippines: A Time Series Analysis

ERIC Educational Resources Information Center

de Castro, Belinda V.; de Guzman, Allan B.

2013-01-01

While the issue on the existence of shadow education institutions (SEI's) has only recently been the subject of investigation in studies in various countries worldwide, it is clear that its market is a huge industry in much of Asia and is growing fast elsewhere. Capitalizing on the annual number of SEI's gathered from key government agencies and…

Facile synthesis of hollow Sn-Co@PMMA nanospheres as high performance anodes for lithium-ion batteries via galvanic replacement reaction and in situ polymerization

NASA Astrophysics Data System (ADS)

Yu, Xiaohui; Jiang, Anni; Yang, Hongyan; Meng, Haowen; Dou, Peng; Ma, Daqian; Xu, Xinhua

2015-08-01

Polymethyl methacrylate (PMMA)-coated hollow Sn-Co nanospheres (Sn-Co@PMMA) with superior electrochemical performance had been synthesized via a facile galvanic replacement method followed by an in situ emulsion polymerization route. The properties were investigated in detail and results show that the hollow Sn-Co nanospheres were evenly coated with PMMA. Benefiting from the protection of the PMMA layers, the hollow Sn-Co@PMMA nanocomposite is capable of retaining a high capacity of 590 mAh g-1 after 100 cycles with a coulomb efficiency above 98%, revealing better electrochemical properties compared with hollow Sn-Co anodes. The PMMA coating could help accommodate the mechanical strain caused by volume expansion and stabilize the solid electrolyte interphase (SEI) film formed on the electrode. Such a facile process could be further extended to other anode materials for lithium-ion batteries.

SAMHD1 controls cell cycle status, apoptosis and HIV-1 infection in monocytic THP-1 cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonifati, Serena; Daly, Michele B.; St Gelais, Corine

SAMHD1 limits HIV-1 infection in non-dividing myeloid cells by decreasing intracellular dNTP pools. HIV-1 restriction by SAMHD1 in these cells likely prevents activation of antiviral immune responses and modulates viral pathogenesis, thus highlighting a critical role of SAMHD1 in HIV-1 physiopathology. Here, we explored the function of SAMHD1 in regulating cell proliferation, cell cycle progression and apoptosis in monocytic THP-1 cells. Using the CRISPR/Cas9 technology, we generated THP-1 cells with stable SAMHD1 knockout. We found that silencing of SAMHD1 in cycling cells stimulates cell proliferation, redistributes cell cycle population in the G{sub 1}/G{sub 0} phase and reduces apoptosis. These alterationsmore » correlated with increased dNTP levels and more efficient HIV-1 infection in dividing SAMHD1 knockout cells relative to control. Our results suggest that SAMHD1, through its dNTPase activity, affects cell proliferation, cell cycle distribution and apoptosis, and emphasize a key role of SAMHD1 in the interplay between cell cycle regulation and HIV-1 infection.« less

Selective Effects of PD-1 on Akt and Ras Pathways Regulate Molecular Components of the Cell Cycle and Inhibit T Cell Proliferation

PubMed Central

Patsoukis, Nikolaos; Brown, Julia; Petkova, Victoria; Liu, Fang; Li, Lequn; Boussiotis, Vassiliki A.

2017-01-01

The receptor programmed death 1 (PD-1) inhibits T cell proliferation and plays a critical role in suppressing self-reactive T cells, and it also compromises antiviral and antitumor responses. To determine how PD-1 signaling inhibits T cell proliferation, we used human CD4+ T cells to examine the effects of PD-1 signaling on the molecular control of the cell cycle. The ubiquitin ligase SCFSkp2 degrades p27kip1, an inhibitor of cyclin-dependent kinases (Cdks), and PD-1 blocked cell cycle progression through the G1 phase by suppressing transcription of SKP2, which encodes a component of this ubiquitin ligase. Thus, in T cells stimulated through PD-1, Cdks were not activated, and two critical Cdk substrates were not phosphorylated. Activation of PD-1 inhibited phosphorylation of the retinoblastoma gene product, which suppressed expression of E2F target genes. PD-1 also inhibited phosphorylation of the transcription factor Smad3, which increased its activity. These events induced additional inhibitory checkpoints in the cell cycle by increasing the abundance of the G1 phase inhibitor p15INK4 and repressing the Cdk-activating phosphatase Cdc25A. PD-1 suppressed SKP2 transcription by inhibiting phosphoinositide 3-kinase–Akt and Ras–mitogen-activated and extracellular signal–regulated kinase kinase (MEK)–extracellular signal–regulated kinase (ERK) signaling. Exposure of cells to the proliferation-promoting cytokine interleukin-2 restored activation of MEK-ERK signaling, but not Akt signaling, and only partially restored SKP2 expression. Thus, PD-1 blocks cell cycle progression and proliferation of T lymphocytes by affecting multiple regulators of the cell cycle. PMID:22740686

Microporous Carbon Polyhedrons Encapsulated Polyacrylonitrile Nanofibers as Sulfur Immobilizer for Lithium-Sulfur Battery.

PubMed

Zhang, Ye-Zheng; Wu, Zhen-Zhen; Pan, Gui-Ling; Liu, Sheng; Gao, Xue-Ping

2017-04-12

Microporous carbon polyhedrons (MCPs) are encapsulated into polyacrylonitrile (PAN) nanofibers by electrospinning the mixture of MCPs and PAN. Subsequently, the as-prepared MCPs-PAN nanofibers are employed as sulfur immobilizer for lithium-sulfur battery. Here, the S/MCPs-PAN multicomposites integrate the advantage of sulfur/microporous carbon and sulfurized PAN. Specifically, with large pore volume, MCPs inside PAN nanofibers provide a sufficient sulfur loading. While PAN-based nanofibers offer a conductive path and matrix. Therefore, the electrochemical performance is significantly improved for the S/MCPs-PAN multicomposite with a suitable sulfur content in carbonate-based electrolyte. At the current density of 160 mA g -1 sulfur , the S/MPCPs-PAN composite delivers a large discharge capacity of 789.7 mAh g -1 composite , high Coulombic efficiency of about 100% except in the first cycle, and good capacity retention after 200 cycles. In particular, even at 4 C rate, the S/MCPs-PAN composite can still release the discharge capacity of 370 mAh g -1 composite . On the contrary, the formation of the thick SEI layer on the surface of nanofibers with a high sulfur content are observed, which is responsible for the quick capacity deterioration of the sulfur-based composite in carbonate-based electrolyte. This design of the S/MCPs-PAN multicomposite is helpful for the fabrication of stable Li-S battery.

Cell cycle regulation of the BRCA1/acetyl-CoA-carboxylase complex.

PubMed

Ray, H; Suau, F; Vincent, A; Dalla Venezia, N

2009-01-16

Germ-line alterations in BRCA1 are associated with an increased susceptibility to breast and ovarian cancer. The BRCA1 protein has been implicated in multiple cellular functions. We have recently demonstrated that BRCA1 reduces acetyl-CoA-carboxylase alpha (ACCA) activity through its phospho-dependent binding to ACCA, and further established that the phosphorylation of the Ser1263 of ACCA is required for this interaction. Here, to gain more insight into the cellular conditions that trigger the BRCA1/ACCA interaction, we designed an anti-pSer1263 antibody and demonstrated that the Ser1263 of ACCA is phosphorylated in vivo, in a cell cycle-dependent manner. We further showed that the interaction between BRCA1 and ACCA is regulated during cell cycle progression. Taken together, our findings reveal a novel mechanism of regulation of ACCA distinct from the previously described phosphorylation of Ser79, and provide new insights into the control of lipogenesis through the cell cycle.

Alkyl Pyrocarbonate Electrolyte Additives for Performance Enhancement of Li Ion Cells

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Surampudi, S.

2000-01-01

Lithium ion rechargeable batteries are being developed for various aerospace applications under a NASA-DoD Interagency program. These applications require further improvements in several areas, specifically in the cycle life for LEO and GEO satellites and in the low temperature performance for the Mars Lander and Rover missions. Accordingly, we have been pursuing research studies to achieve improvement in the low temperature performance, long cycle life and active life of Li ion cells. The studies are mainly focused on electrolytes, to identify newer formulations of new electrolyte additives to enhance Li permeability (at low temperatures) and stability towards the electrode. The latter approach is particularly aimed at the formation suitable SEI (solid electrolyte interphase) on carbon electrodes. In this paper, we report the beneficial effect of using alkyl pyrocarbonates as electrolyte additives to improve the low temperature performance of Li ion cells.

Modeling of combined capacity fade with thermal effects for a cycled LixC6-LiyMn2O4 cell

NASA Astrophysics Data System (ADS)

Vazquez-Arenas, Jorge; Fowler, Michael; Mao, Xiaofeng; Chen, Shih-ken

2012-10-01

Li-ion batteries are the most promising technology for use in electric vehicles in the near future, and as such it is critical to understand their performance at both beginning of life (BOL) and end of life (EOL). In this work different thermal and capacity fade effects (e.g. SEI formation, dissolution of LiyMn2O4 particles) are modeled to account comprehensively for the behavior of a LixC6-LiyMn2O4 cell. The comparison between baseline and complex models is systematically used to analyze individual contributions and perform a deeper evaluation of the variables affecting the capacity fade with thermal inputs during typical cycle life tests. Some modifications in the original model are proposed to better describe the behavior of the cell and speed up the calculations.

Cell cycle gene expression under clinorotation

NASA Astrophysics Data System (ADS)

Artemenko, Olga

2016-07-01

Cyclins and cyclin-dependent kinase (CDK) are main regulators of the cell cycle of eukaryotes. It's assumes a significant change of their level in cells under microgravity conditions and by other physical factors actions. The clinorotation use enables to determine the influence of gravity on simulated events in the cell during the cell cycle - exit from the state of quiet stage and promotion presynthetic phase (G1) and DNA synthesis phase (S) of the cell cycle. For the clinorotation effect study on cell proliferation activity is the necessary studies of molecular mechanisms of cell cycle regulation and development of plants under altered gravity condition. The activity of cyclin D, which is responsible for the events of the cell cycle in presynthetic phase can be controlled by the action of endogenous as well as exogenous factors, but clinorotation is one of the factors that influence on genes expression that regulate the cell cycle.These data can be used as a model for further research of cyclin - CDK complex for study of molecular mechanisms regulation of growth and proliferation. In this investigation we tried to summarize and analyze known literature and own data we obtained relatively the main regulators of the cell cycle in altered gravity condition.

APPLICATIONS OF A MODEL FOR THE HORMONAL REGULATION OF THE MENSTRUAL CYCLE

EPA Science Inventory

APPLICATIONS OF A MODEL FOR THE HORMONAL REGULATION OF THE MENSTRUAL CYCLE. Leona H. Clark1, Paul M. Schlosser2, and James F. Selgrade3. 1US Environmental Protection Agency, ORD, NHEERL, ETD, Research Triangle Park, NC; 2CIIT, Research Triangle Park, NC; 3North Carolina State Un...

The Electrochemistry of Fe 3 O 4 /Polypyrrole Composite Electrodes in Lithium-Ion Cells: The Role of Polypyrrole in Capacity Retention

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruck, Andrea M.; Gannett, Cara N.; Bock, David C.

In two series of magnetite (Fe 3O4) composite electrodes, one group with and one group without added carbon, containing varying quantities of polypyrrole (PPy), and a non-conductive polyvinylidene difluoride (PVDF) binder were constructed and then analyzed using electrochemical and spectroscopic techniques. Galvanostatic cycling and alternating current (AC) impedance measurements were used in tandem to measure delivered capacity, capacity retention, and the related impedance at various stages of discharge and charge. Further, the reversibility of Fe 3O 4 to iron metal (Fe0) conversion observed during discharge was quantitatively assessed ex-situ using X-ray Absorption Spectroscopy (XAS). The Fe 3O 4 composite containingmore » the largest weight fraction of PPy (20 wt%) with added carbon demonstrated reduced irreversible capacity on initial cycles and improved cycling stability over 50 cycles, attributed to decreased reaction with the electrolyte in the presence of PPy. Our study illustrated the beneficial role of PPy addition to Fe 3O 4 based electrodes was not strongly related to improved electrical conductivity, but rather to improved ion transport related to the formation of a more favorable surface electrolyte interphase (SEI).« less

The Electrochemistry of Fe 3 O 4 /Polypyrrole Composite Electrodes in Lithium-Ion Cells: The Role of Polypyrrole in Capacity Retention

DOE PAGES

Bruck, Andrea M.; Gannett, Cara N.; Bock, David C.; ...

2016-12-15

In two series of magnetite (Fe 3O4) composite electrodes, one group with and one group without added carbon, containing varying quantities of polypyrrole (PPy), and a non-conductive polyvinylidene difluoride (PVDF) binder were constructed and then analyzed using electrochemical and spectroscopic techniques. Galvanostatic cycling and alternating current (AC) impedance measurements were used in tandem to measure delivered capacity, capacity retention, and the related impedance at various stages of discharge and charge. Further, the reversibility of Fe 3O 4 to iron metal (Fe0) conversion observed during discharge was quantitatively assessed ex-situ using X-ray Absorption Spectroscopy (XAS). The Fe 3O 4 composite containingmore » the largest weight fraction of PPy (20 wt%) with added carbon demonstrated reduced irreversible capacity on initial cycles and improved cycling stability over 50 cycles, attributed to decreased reaction with the electrolyte in the presence of PPy. Our study illustrated the beneficial role of PPy addition to Fe 3O 4 based electrodes was not strongly related to improved electrical conductivity, but rather to improved ion transport related to the formation of a more favorable surface electrolyte interphase (SEI).« less

Lis1 regulates dynein by sterically blocking its mechanochemical cycle

PubMed Central

Toropova, Katerina; Zou, Sirui; Roberts, Anthony J; Redwine, William B; Goodman, Brian S; Reck-Peterson, Samara L; Leschziner, Andres E

2014-01-01

Regulation of cytoplasmic dynein's motor activity is essential for diverse eukaryotic functions, including cell division, intracellular transport, and brain development. The dynein regulator Lis1 is known to keep dynein bound to microtubules; however, how this is accomplished mechanistically remains unknown. We have used three-dimensional electron microscopy, single-molecule imaging, biochemistry, and in vivo assays to help establish this mechanism. The three-dimensional structure of the dynein–Lis1 complex shows that binding of Lis1 to dynein's AAA+ ring sterically prevents dynein's main mechanical element, the ‘linker’, from completing its normal conformational cycle. Single-molecule experiments show that eliminating this block by shortening the linker to a point where it can physically bypass Lis1 renders single dynein motors insensitive to regulation by Lis1. Our data reveal that Lis1 keeps dynein in a persistent microtubule-bound state by directly blocking the progression of its mechanochemical cycle. DOI: http://dx.doi.org/10.7554/eLife.03372.001 PMID:25380312

How many records should be used in ASCE/SEI-7 ground motion scaling procedure?

USGS Publications Warehouse

Reyes, Juan C.; Kalkan, Erol

2012-01-01

U.S. national building codes refer to the ASCE/SEI-7 provisions for selecting and scaling ground motions for use in nonlinear response history analysis of structures. Because the limiting values for the number of records in the ASCE/SEI-7 are based on engineering experience, this study examines the required number of records statistically, such that the scaled records provide accurate, efficient, and consistent estimates of “true” structural responses. Based on elastic–perfectly plastic and bilinear single-degree-of-freedom systems, the ASCE/SEI-7 scaling procedure is applied to 480 sets of ground motions; the number of records in these sets varies from three to ten. As compared to benchmark responses, it is demonstrated that the ASCE/SEI-7 scaling procedure is conservative if fewer than seven ground motions are employed. Utilizing seven or more randomly selected records provides more accurate estimate of the responses. Selecting records based on their spectral shape and design spectral acceleration increases the accuracy and efficiency of the procedure.

Practical high temperature (80 °C) storage study of industrially manufactured Li-ion batteries with varying electrolytes

NASA Astrophysics Data System (ADS)

Genieser, R.; Loveridge, M.; Bhagat, R.

2018-05-01

A previous study is focused on high temperature cycling of industrially manufactured Li-ion pouch cells (NMC-111/Graphite) with different electrolytes at 80 °C [JPS 373 (2018) 172-183]. Within this article the same test set-up is used, with cells stored for 30 days at different open circuit potentials and various electrolytes instead of electrochemical cycling. The most pronounced cell degradation (capacity fade and resistance increase) happens at high potentials. However appropriate electrolyte formulations are able to suppress ageing conditions by forming passivating surface films on both electrodes. Compared with electrochemical cycling at 80 °C, cells with enhanced electrolytes only show a slight resistance increase during storage and the capacity fade is much lower. Additionally it is shown for the first time, that the resistance is decreasing and capacity is regained once these cells are cycled again at room temperature. This is not the case for electrolytes without additives or just vinylene carbonate (VC) as an additive. It is further shown that the resistance increase of cells with the other electrolytes is accompanied by a reduction of the cell volume during further cycling. This behaviour is likely related to the reduction of CO2 at the anode to form additional SEI layer components.

Cdk1 activity acts as a quantitative platform for coordinating cell cycle progression with periodic transcription

PubMed Central

Banyai, Gabor; Baïdi, Feriel; Coudreuse, Damien; Szilagyi, Zsolt

2016-01-01

Cell proliferation is regulated by cyclin-dependent kinases (Cdks) and requires the periodic expression of particular gene clusters in different cell cycle phases. However, the interplay between the networks that generate these transcriptional oscillations and the core cell cycle machinery remains largely unexplored. In this work, we use a synthetic regulable Cdk1 module to demonstrate that periodic expression is governed by quantitative changes in Cdk1 activity, with different clusters directly responding to specific activity levels. We further establish that cell cycle events neither participate in nor interfere with the Cdk1-driven transcriptional program, provided that cells are exposed to the appropriate Cdk1 activities. These findings contrast with current models that propose self-sustained and Cdk1-independent transcriptional oscillations. Our work therefore supports a model in which Cdk1 activity serves as a quantitative platform for coordinating cell cycle transitions with the expression of critical genes to bring about proper cell cycle progression. PMID:27045731

Cycle stability of the electrochemical capacitors patterned with vertically aligned carbon nanotubes in an LiPF6-based electrolyte.

PubMed

Chiou, Yi-Deng; Tsai, Dah-Shyang; Lam, Hoa Hung; Chang, Chuan-hua; Lee, Kuei-Yi; Huang, Ying-Sheng

2013-09-07

The miniature ultracapacitors, with interdigitated electrodes of vertically aligned carbon nanotubes (VACNTs) and an inter-electrode gap of 20 μm, have been prepared in the LiPF6 organic electrolyte with and without PVdF-HFP gel. PVdF-HFP between two opposing electrodes enhances the device reliability, but lessens its power performance because of the extra diffusion resistance. Also noteworthy are the gel influences on the cycle stability. When the applied voltage is 2.0 or 2.5 V, both the LiPF6 and the gel capacitors exhibit excellent stability, typified by a retention ratio of ≥95% after 10,000 cycles. Their coulombic efficiencies quickly rise up, and hold steady at 100%. Nonetheless, when the applied voltage is 3.5 or 4.0 V, the cycle stability deteriorates, since the negative electrode potential descends below 0.9 V (vs. Li), leading to electrolyte decomposition and SEI formation. For the LiPF6 capacitor, its retention ratio could be around 60% after 10,000 cycles and the coulombic efficiency of 100% is difficult to reach throughout its cycle life. On the other hand, the gel capacitor cycles energy with a much higher retention ratio, >80% after 10,000 cycles, and a better coulombic efficiency, even though electrolyte decomposition still occurs. We attribute the superior stability of the gel capacitor to its extra diffusion resistance which slows down the performance deterioration.

Revealing the cellular localization of STAT1 during the cell cycle by super-resolution imaging

PubMed Central

Gao, Jing; Wang, Feng; Liu, Yanhou; Cai, Mingjun; Xu, Haijiao; Jiang, Junguang; Wang, Hongda

2015-01-01

Signal transducers and activators of transcription (STATs) can transduce cytokine signals and regulate gene expression. The cellular localization and nuclear trafficking of STAT1, a representative of the STAT family with multiple transcriptional functions, is tightly related with transcription process, which usually happens in the interphase of the cell cycle. However, these priority questions regarding STAT1 distribution and localization at the different cell-cycle stages remain unclear. By using direct stochastic optical reconstruction microscopy (dSTORM), we found that the nuclear expression level of STAT1 increased gradually as the cell cycle carried out, especially after EGF stimulation. Furthermore, STAT1 formed clusters in the whole cell during the cell cycle, with the size and the number of clusters also increasing significantly from G1 to G2 phase, suggesting that transcription and other cell-cycle related activities can promote STAT1 to form more and larger clusters for fast response to signals. Our work reveals that the cellular localization and clustering distribution of STAT1 are associated with the cell cycle, and further provides an insight into the mechanism of cell-cycle regulated STAT1 signal transduction. PMID:25762114

Software Estimation: Developing an Accurate, Reliable Method

DTIC Science & Technology

2011-08-01

Lake, CA ,93555- 6110 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S...Activity, the systems engineering team is responsible for system and software requirements. 2 . Process Dashboard is a software planning and tracking tool... CA 93555- 6110 760-939-6989 Brad Hodgins is an interim TSP Mentor Coach, SEI-Authorized TSP Coach, SEI-Certified PSP/TSP Instructor, and SEI

Analysis of the VIDAS® Staph Enterotoxin III (SET3) for Detection of Staphylococcal Enterotoxins G, H, and I in Foods.

PubMed

Hait, Jennifer M; Nguyen, Angela T; Tallent, Sandra M

2018-04-20

Background : Staphylococcal food poisoning (SFP) frequently causes illnesses worldwide. SFP occurs from the ingestion of staphylococcal enterotoxins (SEs) preformed in foods by enterotoxigenic strains of Staphylococcus species, primarily S. aureus . SEG, SEH, and SEI induce emesis and have been implicated in outbreaks. Immunological-based methods are deemed the most practical methods for the routine analysis of SEs in foods given their ease of use, sensitivity, specificity, and commercial availability. These kits are routinely used to test for SEA-SEE. However, only recently has a kit been developed to detect SEG, SEH, and SEI. Objective: Our research examined the performance of the novel VIDAS ® Staph Enterotoxin III (SET3) for the detection of staphylococcal enterotoxins SEG, SEH, and SEI in foods. Methods : Here we assess the sensitivity and specificity of SET3 using duplicate test portions of six foods at varying concentrations of inclusivity and exclusivity inocula: pure SEG, SEH, SEI, S. aureus strain extracts positive for seg, seh , and sei , as well as SEA, SEB, SEC, SED, and SEE. Results : The overall detection limit was less than 2.09 ng/mL for foods inoculated with SEG, SEH, and SEI, with no cross reactivity observed. Highlights : Integrating concurrent testing to detect the presence of SEA-SEE and SEG-SEI utilizing the SET3 along with the VIDAS SET2, Ridascreen ® SET total, or other comparable kits will be instrumental for the future food assessments in our laboratory and may become the new standard for SE analysis of foods.

Measuring perceived effects of drinking an extract of basidiomycetes Agaricus blazei murill: a survey of Japanese consumers with cancer

PubMed Central

Talcott, James A; Clark, Jack A; Lee, Insu P

2007-01-01

Background To survey cancer patients who consume an extract of the Basidiomycetes Agaricus blazei Murill mushroom (Sen-Sei-Ro) to measure their self-assessment of its effects and to develop an instrument for use in future randomized trials. Methods We designed, translated and mailed a survey to 2,346 Japanese consumers of Sen-Sei-Ro self-designated as cancer patients. The survey assessed consumer demographics, cancer history, Sen-Sei-Ro consumption, and its perceived effects. We performed exploratory psychometric analyses to identify distinct, multi-item scales that could summarize perceptions of effects. Results We received completed questionnaires from 782 (33%) of the sampled Sen-Sei-Ro consumers with a cancer history. Respondents represented a broad range of cancer patients familiar with Sen-Sei-Ro. Nearly all had begun consumption after their cancer diagnosis. These consumers expressed consistently positive views, though not extremely so, with more benefit reported for more abstract benefits such as emotional and physical well-being than relief of specific symptoms. We identified two conceptually and empirically distinct and internally consistent summary scales measuring Sen-Sei-Ro consumers' perceptions of its effects, Relief of Symptoms and Functional Well-being (Cronbach's alpha: Relief of Symptoms, α = .74; Functional Well-Being, α = .91). Conclusion Respondents to our survey of Sen-Sei-Ro consumers with cancer reported favorable perceived effects from its use. Our instrument, when further validated, may be a useful outcome in trials assessing this and other complementary and alternative medicine (CAM) substances in cancer patients. PMID:17967191

Scalable Synthesis of Defect Abundant Si Nanorods for High-Performance Li-Ion Battery Anodes.

PubMed

Wang, Jing; Meng, Xiangcai; Fan, Xiulin; Zhang, Wenbo; Zhang, Hongyong; Wang, Chunsheng

2015-06-23

Microsized nanostructured silicon-carbon composite is a promising anode material for high energy Li-ion batteries. However, large-scale synthesis of high-performance nano-Si materials at a low cost still remains a significant challenge. We report a scalable low cost method to synthesize Al/Na-doped and defect-abundant Si nanorods that have excellent electrochemical performance with high first-cycle Coulombic efficiency (90%). The unique Si nanorods are synthesized by acid etching the refined and rapidly solidified eutectic Al-Si ingot. To maintain the high electronic conductivity, a thin layer of carbon is then coated on the Si nanorods by carbonization of self-polymerized polydopamine (PDA) at 800 °C. The carbon coated Si nanorods (Si@C) electrode at 0.9 mg cm(-2) loading (corresponding to area-specific-capacity of ∼2.0 mAh cm(-2)) exhibits a reversible capacity of ∼2200 mAh g(-1) at 100 mA g(-1) current, and maintains ∼700 mAh g(-1) over 1000 cycles at 1000 mA g(-1) with a capacity decay rate of 0.02% per cycle. High Coulombic efficiencies of 87% in the first cycle and ∼99.7% after 5 cycles are achieved due to the formation of an artificial Al2O3 solid electrolyte interphase (SEI) on the Si surface, and the low surface area (31 m(2) g(-1)), which has never been reported before for nano-Si anodes. The excellent electrochemical performance results from the massive defects (twins, stacking faults, dislocations) and Al/Na doping in Si nanorods induced by rapid solidification and Na salt modifications; this greatly enhances the robustness of Si from the volume changes and alleviates the mechanical stress/strain of the Si nanorods during the lithium insertion/extraction process. Introducing massive defects and Al/Na doping in eutectic Si nanorods for Li-ion battery anodes is unexplored territory. We venture this uncharted territory to commercialize this nanostructured Si anode for the next generation of Li-ion batteries.

An extensive program of periodic alternative splicing linked to cell cycle progression

PubMed Central

Dominguez, Daniel; Tsai, Yi-Hsuan; Weatheritt, Robert; Wang, Yang; Blencowe, Benjamin J; Wang, Zefeng

2016-01-01

Progression through the mitotic cell cycle requires periodic regulation of gene function at the levels of transcription, translation, protein-protein interactions, post-translational modification and degradation. However, the role of alternative splicing (AS) in the temporal control of cell cycle is not well understood. By sequencing the human transcriptome through two continuous cell cycles, we identify ~1300 genes with cell cycle-dependent AS changes. These genes are significantly enriched in functions linked to cell cycle control, yet they do not significantly overlap genes subject to periodic changes in steady-state transcript levels. Many of the periodically spliced genes are controlled by the SR protein kinase CLK1, whose level undergoes cell cycle-dependent fluctuations via an auto-inhibitory circuit. Disruption of CLK1 causes pleiotropic cell cycle defects and loss of proliferation, whereas CLK1 over-expression is associated with various cancers. These results thus reveal a large program of CLK1-regulated periodic AS intimately associated with cell cycle control. DOI: http://dx.doi.org/10.7554/eLife.10288.001 PMID:27015110

Rational design of anode materials based on Group IVA elements (Si, Ge, and Sn) for lithium-ion batteries.

PubMed

Wu, Xing-Long; Guo, Yu-Guo; Wan, Li-Jun

2013-09-01

Lithium-ion batteries (LIBs) represent the state-of-the-art technology in rechargeable energy-storage devices and they currently occupy the prime position in the marketplace for powering an increasingly diverse range of applications. However, the fast development of these applications has led to increasing demands being placed on advanced LIBs in terms of higher energy/power densities and longer life cycles. For LIBs to meet these requirements, researchers have focused on active electrode materials, owing to their crucial roles in the electrochemical performance of batteries. For anode materials, compounds based on Group IVA (Si, Ge, and Sn) elements represent one of the directions in the development of high-capacity anodes. Although these compounds have many significant advantages when used as anode materials for LIBs, there are still some critical problems to be solved before they can meet the high requirements for practical applications. In this Focus Review, we summarize a series of rational designs for Group IVA-based anode materials, in terms of their chemical compositions and structures, that could address these problems, that is, huge volume variations during cycling, unstable surfaces/interfaces, and invalidation of transport pathways for electrons upon cycling. These designs should at least include one of the following structural benefits: 1) Contain a sufficient number of voids to accommodate the volume variations during cycling; 2) adopt a "plum-pudding"-like structure to limit the volume variations during cycling; 3) facilitate an efficient and permanent transport pathway for electrons and lithium ions; or 4) show stable surfaces/interfaces to stabilize the in situ formed SEI layers. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Disruption of the hedgehog signaling pathway contributes to the hair follicle cycling deficiency in Vdr knockout mice.

PubMed

Teichert, Arnaud; Elalieh, Hashem; Bikle, Daniel

2010-11-01

Mice null for the Vitamin D receptor (VdrKO) have a disrupted first hair follicle cycle and aborted subsequent hair follicle cycling. We examined the expression of different markers and mediators of hair follicle cycling in the hair follicle of the VdrKO mouse during days 13-22 when the hair follicle normally initiates and completes the first catagen. We compared the expression of those genes in mice with a nonsense mutation in hairless (Rhino), which have a similar alopecia phenotype, and to Cyp27b1 null mice which are deficient in the production of 1,25(OH)2D3, the Vdr ligand, but display normal hair follicle cycling. Our results demonstrate the down regulation of hair follicle markers and the alteration of expression of hedgehog (Hh), Wnt, Fgf, and Tgfbeta pathways in VdrKO and Rhino mice, but not in Cyp27b1KO mice. Treatment of VdrKO mice with an agonist to the Hh pathway partially restored hair follicle cycling, suggesting a role of this pathway in the regulation of hair follicle cycling by VDR. These results suggest that Vdr regulates directly or indirectly the expression of genes required for hair follicle cycling, including Hh signaling, independent of 1,25(OH)2D3. (c) 2010 Wiley-Liss, Inc.

Additive effect on reductive decomposition and binding of carbonate-based solvent toward solid electrolyte interphase formation in lithium-ion battery.

PubMed

Ushirogata, Keisuke; Sodeyama, Keitaro; Okuno, Yukihiro; Tateyama, Yoshitaka

2013-08-14

The solid-electrolyte interphase (SEI) formed through the reductive decomposition of solvent molecules plays a crucial role in the stability and capability of a lithium-ion battery (LIB). Here we investigated the effects of adding vinylene carbonate (VC) to ethylene carbonate (EC) solvent, a typical electrolyte in LIBs, on the reductive decomposition. We focused on both thermodynamics and kinetics of the possible processes and used density functional theory-based molecular dynamics with explicit solvent and Blue-moon ensemble technique for the free energy change. We considered Li(+) in only EC solvent (EC system) and in EC solvent with a VC additive (EC/VC system) to elucidate the additive effects. In addition to clarifying the equilibrium properties, we evaluated the free energy changes along several EC or VC decomposition pathways under one-electron (1e) reduction condition. Two-electron (2e) reduction and attacks of anion radicals to intact molecules were also examined. The present results completely reproduce the gaseous products observed in the experiments. We also found a new mechanism involving the VC additive: the VC additive preferentially reacts with the EC anion radical to suppress the 2e reduction of EC and enhance the initial SEI formation, contrary to the conventional scenario in which VC additive is sacrificially reduced and its radical oligomerization becomes the source of SEI. Because our mechanism needs only 1e reduction, the irreversible capacity at the SEI formation will decrease, which is also consistent with the experimental observations. These results reveal the primary role of VC additive in the EC solvent.

The Rho GTPase effector ROCK regulates cyclin A, cyclin D1, and p27Kip1 levels by distinct mechanisms.

PubMed

Croft, Daniel R; Olson, Michael F

2006-06-01

The members of the Rho GTPase family are well known for their regulation of actin cytoskeletal structures. In addition, they influence progression through the cell cycle. The RhoA and RhoC proteins regulate numerous effector proteins, with a central and vital signaling role mediated by the ROCK I and ROCK II serine/threonine kinases. The requirement for ROCK function in the proliferation of numerous cell types has been revealed by studies utilizing ROCK-selective inhibitors such as Y-27632. However, the mechanisms by which ROCK signaling promotes cell cycle progression have not been thoroughly characterized. Using a conditionally activated ROCK-estrogen receptor fusion protein, we found that ROCK activation is sufficient to stimulate G1/S cell cycle progression in NIH 3T3 mouse fibroblasts. Further analysis revealed that ROCK acts via independent pathways to alter the levels of cell cycle regulatory proteins: cyclin D1 and p21(Cip1) elevation via Ras and the mitogen-activated protein kinase pathway, increased cyclin A via LIM kinase 2, and reduction of p27(Kip1) protein levels. Therefore, the influence of ROCK on cell cycle regulatory proteins occurs by multiple independent mechanisms.

Evidence that P12, a specific variant of P16{sup INK4A}, plays a suppressive role in human pancreatic carcinogenesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poi, Ming J.; Knobloch, Thomas J.; Division of Environmental Health Sciences, College of Public Health, The Ohio State University, Columbus, OH 43210

2013-06-28

Highlights: •P12, a variant of P16{sup INK4A}, inhibits the proliferation of pancreatic cancer cells. •P12 is distinct from P16 in function and structure. •Genetic alterations of p12 are prevalent in human pancreatic carcinoma. •P12 represents a potential pancreas-specific tumor suppressor. -- Abstract: The INK4a-ARF locus plays a central role in the development of pancreatic tumors as evidenced by the fact that up to 98% of pancreatic tumor specimens harbored genetic alterations at the INK4a-ARF locus. Interestingly, in addition to the well-known P16{sup INK4A} (P16) and P14ARF tumor suppressors, the INK4a-ARF locus in pancreas encodes another protein, P12, whose structure, function,more » and contributions to pancreatic carcinogenesis remain to be elucidated. In the current study, we demonstrated that over-expression of p12 in human pancreatic cancer cells led to cell arrest at the G1 phase and such cell cycle arrest was related to down-regulation of a number of oncogenes, such as c-Jun, Fos, and SEI1. Furthermore, unlike P16, P12 did not retain any cyclin-dependent kinase 4 (CDK4)-inhibitory activity. Instead, P12 exhibited a transactivating activity not found in P16. We also examined the genetic status of p12 in a cohort of 40 pancreatic tumor specimens and found that p12 alteration was prevalent in pancreatic tumors with an incidence of 70% (28/40). These results support that P12 is a tumor suppressive protein distinct from P16, and its genetic inactivation is associated with pancreatic carcinogenesis.« less

Solid State Multinuclear Magnetic Resonance Investigation of Electrolyte Decomposition Products on Lithium Ion Electrodes

NASA Technical Reports Server (NTRS)

DeSilva, J .H. S. R.; Udinwe, V.; Sideris, P. J.; Smart, M. C.; Krause, F. C.; Hwang, C.; Smith, K. A.; Greenbaum, S. G.

2012-01-01

Solid electrolyte interphase (SEI) formation in lithium ion cells prepared with advanced electrolytes is investigated by solid state multinuclear (7Li, 19F, 31P) magnetic resonance (NMR) measurements of electrode materials harvested from cycled cells subjected to an accelerated aging protocol. The electrolyte composition is varied to include the addition of fluorinated carbonates and triphenyl phosphate (TPP, a flame retardant). In addition to species associated with LiPF6 decomposition, cathode NMR spectra are characterized by the presence of compounds originating from the TPP additive. Substantial amounts of LiF are observed in the anodes as well as compounds originating from the fluorinated carbonates.

Propulsion for the lunar mission

NASA Technical Reports Server (NTRS)

Jones, Lee W.; Champion, Robert H., Jr.

1990-01-01

The paper describes the selection process utilized by NASA during the conduct of the 90-day study of the mission set that is known as the Space Exploration Initiative (SEI). It is directed specifically toward propulsion system definition and selection, with emphasis on the proposed Lunar Transfer Vehicle and the Lunar Exploration Vehicle. Results of trade studies show that selection cannot be readily made on the basis of engine performance alone, because the cost of launching hardware elements and the required propellant are very high. A decision must be made to use either life-cycle costs or annual program costs as the economic figure of merit, because they drive the selection in opposite directions.

Human exploration of space and power development

NASA Technical Reports Server (NTRS)

Cohen, Aaron

1991-01-01

Reasons for mounting the Space Exploration Initiative, the variables facing U.S. planners, and the developmental technologies that will be needed to support this initiative are discussed. The three more advanced technological approaches in the field of power generation described include a lunar-based solar power system, a geosynchronous-based earth orbit solar power satellite system, and the utilization of helium-3/deuterium fusion reaction to create a nuclear fuel cycle. It is noted that the major elements of the SEI will include a heavy-lift launch vehicle, a transfer vehicle and a descent/ascent vehicle for use on lunar missions and adaptable to Mars exploration.

Chemical characterization of the oligosaccharides in Bryde's whale (Balaenoptera edeni) and Sei whale (Balaenoptera borealis lesson) milk.

PubMed

Urashima, Tadasu; Kobayashi, Mami; Asakuma, Sadaki; Uemura, Yusuke; Arai, Ikichi; Fukuda, Kenji; Saito, Tadao; Mogoe, Toshihiro; Ishikawa, Hajime; Fukui, Yutaka

2007-02-01

Samples of milk from a Bryde's whale and a Sei whale contained 2.7 g/100 mL and 1.7 g/100 mL of hexose, respectively. Both contained lactose as the dominant saccharide along with small amounts of Neu5Ac(alpha2-3)Gal(beta1-4)Glc (3'-N-acetylneuraminyllactose), Neu5Ac(alpha2-6)Gal(beta1-4)Glc (6'-N-acetylneuraminyllactose) and Neu5Ac(alpha2-6)Gal(beta1-4)GlcNAc(beta1-3)Gal(beta1-4)Glc (LST c). The dominance of lactose in the carbohydrate of these milks is similar to that of Minke whale milk and bottlenose dolphin colostrum, but the oligosaccharide patterns are different from those of these two species, illustrating the heterogeneity of milk oligosaccharides among the Cetacea.

A Pattern for Increased Monitoring for Intellectual Property Theft by Departing Insiders

DTIC Science & Technology

2012-04-01

2012 TECHNICAL REPORT CMU/SEI-2012-TR-008 ESC-TR-2012-008 CERT® Program http://www.sei.cmu.edu SEI markings v3.2 / 30 August 2011... Programs Conference (PLoP) 2011 (http://www.hillside.net/plop/2011/). This material is based upon work funded and supported by the United States...research project at the CERT® Program is identifying enterprise architectural patterns to protect against the insider threat to organizations. This

High Energy, Long Cycle Life Lithium-ion Batteries for PHEV Application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Donghai; Manthiram, Arumugam; Wang, Chao-Yang

High-loading and high quality PSU Si anode has been optimized and fabricated. The electrochemical performance has been utilized. The PSU Si-graphite anode exhibits the mass loading of 5.8 mg/cm2, charge capacity of 850 mAh/ g and good cycling performance. This optimized electrode has been used for full-cell fabrication. The performance enhancement of Ni-rich materials can be achieved by a diversity of strategies. Higher Mn content and a small amount of Al doping can improve the electrochemical performance by suppressing interfacial side reactions with electrolytes, thus greatly benefiting the cyclability of the samples. Also, surface coatings of Li-rich materials and AlFmore » 3 are able to improve the performance stability of Ni-rich cathodes. One kilogram of optimized concentration-gradient LiNi 0.76Co 0.10Mn 0.14O 2 (CG) with careful control of composition, morphology and electrochemical performance was delivered to our collaborators. The sample achieved an initial specific capacity close to 190 mA h g -1 at C/10 rate and 180 mA h g -1 at C/3 rate as well as good cyclability in pouch full cells with a 4.4 V upper cut-off voltage at room temperature. Electrolyte additive with Si-N skeleton forms a less resistant SEI on the surface of silicon anode (from PSU) as evidenced by the evolution of the impedance at various lithiation/de-lithiation stages and the cycling data The prelithiation result demonstrates a solution processing method to achieve large area, uniform SLMP coating on well-made anode surface for the prelithiation of lithium-ion batteries. The prelithiation effect with this method is applied both in graphite half cells, graphite/NMC full cells, SiO half cells, SiO/NMC full cells, Si-Graphite half cells and Si-Graphite/NMC full cells with improvements in cycle performance and higher first cycle coulombic efficiency than their corresponding cells without SLMP prelithiation. As to the full cell fabrication and test, full pouch cells with high capacity of 2.2 Ah and 1.2 Ah have been fabricated and delivered. The cells show great uniformity and good cycling performance. The prelithiation method effectively compensate the loss in the first cycle. The cell with high energy density and long-cycle life has been achieved.« less

Capacity Fade and Its Mitigation in Li-Ion Cells with Silicon-Graphite Electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bareño, Javier; Shkrob, Ilya A.; Gilbert, James A.

In this study we scrutinize the causes for capacity fade in lithium-ion cells containing silicongraphite (Si-Gr) blends in the negative electrode and examine approaches for minimizing this fade. The causal mechanisms are inferred from data obtained by electrochemistry, microscopy, spectroscopy and thermogravimetry techniques. The presence of SiOxFy signals in the Si-Gr electrode, LixPOyFz compounds in the electrolyte, and SiO2 species on the NCM523 positive electrode, highlight the crucial role of hydrolytically generated HF, which accelerates the degradation of Si particles. The hydrolysis could result from residual moisture in the current electrode fabrication process, which uses aqueous binders. Water can alsomore » be released when silanol groups on the Si nanoparticles react with HF to form Si-F compounds. We note that the primary cause of capacity fade in the full cells is the loss of solid electrolyte interphase (SEI) integrity resulting from volume changes in Si particles during electrochemical cycling. Adding fluoroethylene carbonate (FEC) to the conventional electrolyte slows capacity fade through the formation of a cross linked polymer with elastomeric properties. Further gains in cell longevity are possible by excluding water during electrode fabrication, using hydrolytically stable lithium salts, and adopting electrolyte systems that provide more elasticity to the SEI layers.« less

The relationship between emotional intelligence, previous caring experience and mindfulness in student nurses and midwives: a cross sectional analysis.

PubMed

Snowden, Austyn; Stenhouse, Rosie; Young, Jenny; Carver, Hannah; Carver, Fiona; Brown, Norrie

2015-01-01

Emotional Intelligence (EI), previous caring experience and mindfulness training may have a positive impact on nurse education. More evidence is needed to support the use of these variables in nurse recruitment and retention. To explore the relationship between EI, gender, age, programme of study, previous caring experience and mindfulness training. Cross sectional element of longitudinal study. 938year one nursing, midwifery and computing students at two Scottish Higher Education Institutes (HEIs) who entered their programme in September 2013. Participants completed a measure of 'trait' EI: Trait Emotional Intelligence Questionnaire Short Form (TEIQue-SF); and 'ability' EI: Schutte's et al. (1998) Emotional Intelligence Scale (SEIS). Demographics, previous caring experience and previous training in mindfulness were recorded. Relationships between variables were tested using non-parametric tests. Emotional intelligence increased with age on both measures of EI [TEIQ-SF H(5)=15.157 p=0.001; SEIS H(5)=11.388, p=0.044]. Females (n=786) scored higher than males (n=149) on both measures [TEIQ-SF, U=44,931, z=-4.509, p<.001; SEIS, U=44,744, z=-5.563, p<.001]. Nursing students scored higher that computing students [TEIQ-SF H(5)=46,496, p<.001; SEIS H(5)=33.309, p<0.001. There were no statistically significant differences in TEIQ-SF scores between those who had previous mindfulness training (n=50) and those who had not (n=857) [U=22,980, z=0.864, p = 0.388]. However, median SEIS was statistically significantly different according to mindfulness training [U=25,115.5, z=2.05, p=.039]. Neither measure demonstrated statistically significantly differences between those with (n=492) and without (n=479) previous caring experience, [TEIQ-SF, U=112, 102, z=0.938, p=.348; SEIS, U=115,194.5, z=1.863, p=0.063]. Previous caring experience was not associated with higher emotional intelligence. Mindfulness training was associated with higher 'ability' emotional intelligence. Implications for recruitment, retention and further research are explored. Copyright © 2014. Published by Elsevier Ltd.

Cyclin-dependent kinase inhibitor p20 controls circadian cell-cycle timing

PubMed Central

Laranjeiro, Ricardo; Tamai, T. Katherine; Peyric, Elodie; Krusche, Peter; Ott, Sascha; Whitmore, David

2013-01-01

Specific stages of the cell cycle are often restricted to particular times of day because of regulation by the circadian clock. In zebrafish, both mitosis (M phase) and DNA synthesis (S phase) are clock-controlled in cell lines and during embryo development. Despite the ubiquitousness of this phenomenon, relatively little is known about the underlying mechanism linking the clock to the cell cycle. In this study, we describe an evolutionarily conserved cell-cycle regulator, cyclin-dependent kinase inhibitor 1d (20 kDa protein, p20), which along with p21, is a strongly rhythmic gene and directly clock-controlled. Both p20 and p21 regulate the G1/S transition of the cell cycle. However, their expression patterns differ, with p20 predominant in developing brain and peak expression occurring 6 h earlier than p21. p20 expression is also p53-independent in contrast to p21 regulation. Such differences provide a unique mechanism whereby S phase is set to different times of day in a tissue-specific manner, depending on the balance of these two inhibitors. PMID:23569261

Cyclin-dependent kinase inhibitor p20 controls circadian cell-cycle timing.

PubMed

Laranjeiro, Ricardo; Tamai, T Katherine; Peyric, Elodie; Krusche, Peter; Ott, Sascha; Whitmore, David

2013-04-23

Specific stages of the cell cycle are often restricted to particular times of day because of regulation by the circadian clock. In zebrafish, both mitosis (M phase) and DNA synthesis (S phase) are clock-controlled in cell lines and during embryo development. Despite the ubiquitousness of this phenomenon, relatively little is known about the underlying mechanism linking the clock to the cell cycle. In this study, we describe an evolutionarily conserved cell-cycle regulator, cyclin-dependent kinase inhibitor 1d (20 kDa protein, p20), which along with p21, is a strongly rhythmic gene and directly clock-controlled. Both p20 and p21 regulate the G1/S transition of the cell cycle. However, their expression patterns differ, with p20 predominant in developing brain and peak expression occurring 6 h earlier than p21. p20 expression is also p53-independent in contrast to p21 regulation. Such differences provide a unique mechanism whereby S phase is set to different times of day in a tissue-specific manner, depending on the balance of these two inhibitors.

Regulation of store-operated Ca2+ entry activity by cell cycle dependent up-regulation of Orai2 in brain capillary endothelial cells.

PubMed

Kito, Hiroaki; Yamamura, Hisao; Suzuki, Yoshiaki; Yamamura, Hideto; Ohya, Susumu; Asai, Kiyofumi; Imaizumi, Yuji

2015-04-10

Store-operated Ca(2+) entry (SOCE) via Orai1 and STIM1 complex is supposed to have obligatory roles in the regulation of cellular functions of vascular endothelial cells, while little is known about the contribution of Orai2. Quantitative PCR and Western blot analyses indicated the expression of Orai2 and STIM2, in addition to Orai1 and STIM1 in bovine brain capillary endothelial cell line, t-BBEC117. During the exponential growth of t-BBEC117, the knockdown of Orai1 and STIM1 significantly reduced the SOCE activity, whereas Orai2 and STIM2 siRNAs had no effect. To examine whether endogenous SOCE activity contributes to the regulation of cell cycle progression, t-BBEC117 were synchronized using double thymidine blockage. At the G2/M phase, Ca(2+) influx via SOCE was decreased and Orai2 expression was increased compared to the G0/G1 phase. When Orai2 was knocked down at the G2/M phase, the decrease in SOCE was removed, and cell proliferation was partly attenuated. Taken together, Orai1 significantly contributes to cell proliferation via the functional expression, which is presumably independent of the cell cycle phases. In construct, Orai2 is specifically up-regulated during the G2/M phase, negatively modulates the SOCE activity, and may contribute to the regulation of cell cycle progression in brain capillary endothelial cells. Copyright © 2015 Elsevier Inc. All rights reserved.

Regulation of tomato fruit pericarp development by an interplay between CDKB and CDKA1 cell cycle genes

PubMed Central

Czerednik, Anna; Busscher, Marco; Bielen, Bram A.M.; Wolters-Arts, Mieke; de Maagd, Ruud A.; Angenent, Gerco C.

2012-01-01

Growth of tomato fruits is determined by cell division and cell expansion, which are tightly controlled by factors that drive the core cell cycle. The cyclin-dependent kinases (CDKs) and their interacting partners, the cyclins, play a key role in the progression of the cell cycle. In this study the role of CDKA1, CDKB1, and CDKB2 in fruit development was characterized by fruit-specific overexpression and down-regulation. CDKA1 is expressed in the pericarp throughout development, but is strongly up-regulated in the outer pericarp cell layers at the end of the growth period, when CDKB gene expression has ceased. Overexpression of the CDKB genes at later stages of development and the down-regulation of CDKA1 result in a very similar fruit phenotype, showing a reduction in the number of cell layers in the pericarp and alterations in the desiccation of the fruits. Expression studies revealed that CDKA1 is down-regulated by the expression of CDKB1/2 in CDKB1 and CDKB2 overexpression mutants, suggesting opposite roles for these types of CDK proteins in tomato pericarp development. PMID:22282536

Proliferating cell nuclear antigen (PCNA)-associated KIAA0101/PAF15 protein is a cell cycle-regulated anaphase-promoting complex/cyclosome substrate.

PubMed

Emanuele, Michael J; Ciccia, Alberto; Elia, Andrew E H; Elledge, Stephen J

2011-06-14

The anaphase-promoting complex/cyclosome (APC/C) is a cell cycle-regulated E3 ubiquitin ligase that controls the degradation of substrate proteins at mitotic exit and throughout the G1 phase. We have identified an APC/C substrate and cell cycle-regulated protein, KIAA0101/PAF15. PAF15 protein levels peak in the G2/M phase of the cell cycle and drop rapidly at mitotic exit in an APC/C- and KEN-box-dependent fashion. PAF15 associates with proliferating cell nuclear antigen (PCNA), and depletion of PAF15 decreases the number of cells in S phase, suggesting a role for it in cell cycle regulation. Following irradiation, PAF15 colocalized with γH2AX foci at sites of DNA damage through its interaction with PCNA. Finally, PAF15 depletion led to an increase in homologous recombination-mediated DNA repair, and overexpression caused sensitivity to UV-induced DNA damage. We conclude that PAF15 is an APC/C-regulated protein involved in both cell cycle progression and the DNA damage response.

Regulation of store-operated Ca{sup 2+} entry activity by cell cycle dependent up-regulation of Orai2 in brain capillary endothelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kito, Hiroaki; Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto; Yamamura, Hisao

2015-04-10

Store-operated Ca{sup 2+} entry (SOCE) via Orai1 and STIM1 complex is supposed to have obligatory roles in the regulation of cellular functions of vascular endothelial cells, while little is known about the contribution of Orai2. Quantitative PCR and Western blot analyses indicated the expression of Orai2 and STIM2, in addition to Orai1 and STIM1 in bovine brain capillary endothelial cell line, t-BBEC117. During the exponential growth of t-BBEC117, the knockdown of Orai1 and STIM1 significantly reduced the SOCE activity, whereas Orai2 and STIM2 siRNAs had no effect. To examine whether endogenous SOCE activity contributes to the regulation of cell cyclemore » progression, t-BBEC117 were synchronized using double thymidine blockage. At the G2/M phase, Ca{sup 2+} influx via SOCE was decreased and Orai2 expression was increased compared to the G0/G1 phase. When Orai2 was knocked down at the G2/M phase, the decrease in SOCE was removed, and cell proliferation was partly attenuated. Taken together, Orai1 significantly contributes to cell proliferation via the functional expression, which is presumably independent of the cell cycle phases. In construct, Orai2 is specifically up-regulated during the G2/M phase, negatively modulates the SOCE activity, and may contribute to the regulation of cell cycle progression in brain capillary endothelial cells. - Highlights: • Orai1 is essential for SOCE activity in brain capillary endothelial cells (BCECs). • Cell cycle independent expression of Orai1 regulated SOCE and cell proliferation. • Orai2 was up-regulated only at G2/M phase and this consequently reduced SOCE. • Orai2 as well as Orai1 is a key player controlling SOCE and proliferation in BCECs.« less

Lithium metal protected by atomic layer deposition metal oxide for high performance anodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Lin; Connell, Justin G.; Nie, Anmin

We present that lithium metal is a highly desirable anode material for lithium batteries due to its extremely high theoretical capacity (3860 mA h g -1), low potential (-3.04 V versus standard hydrogen electrode), and low density (0.534 g cm -3). However, dendrite growth during cycling and low coulombic efficiency, resulting in safety hazards and fast battery fading, are huge barriers to commercialization. Herein, we used atomic layer deposition (ALD) to prepare conformal, ultrathin aluminum oxide coatings on lithium. We investigated the growth mechanism during Al 2O 3 ALD on lithium by in situ quartz crystal microbalance and found largermore » growth than expected during the initial cycles. We also discovered that the ALD Al 2O 3 enhances the wettability of the Li surface towards both carbonate and ether electrolytes, leading to uniform and dense SEI formation and reduced electrolyte consumption during battery operation. Scanning electron microscopy verified that the bare Li surfaces become rough and dendritic after electrochemical cycling, whereas the ALD Al 2O 3 coated Li surfaces remain smooth and uniform. Analysis of the Li surfaces after cycling using X-ray photoelectron spectroscopy and in situ transmission electron microscopy revealed that the ALD Al 2O 3 coating remains intact during electrochemical cycling, and that Li ions diffuse through the coating and deposit on the underlying Li. Coin cell testing demonstrated more than two times longer cycling life for the ALD Al 2O 3 protected Li, and a coulombic efficiency as high as ~98% at a practical current rate of 1 mA cm -2. More significantly, when the electrolyte volume was reduced from 20 to 5 μL, the stabilizing effect of the ALD coating became even more pronounced and the cycling life was around four times longer. Finally, these results indicate that ALD Al 2O 3 coatings are a promising strategy to stabilize Li anodes for high performance energy storage devices such as Li–S batteries.« less

Lithium metal protected by atomic layer deposition metal oxide for high performance anodes

DOE PAGES

Chen, Lin; Connell, Justin G.; Nie, Anmin; ...

2017-05-26

We present that lithium metal is a highly desirable anode material for lithium batteries due to its extremely high theoretical capacity (3860 mA h g -1), low potential (-3.04 V versus standard hydrogen electrode), and low density (0.534 g cm -3). However, dendrite growth during cycling and low coulombic efficiency, resulting in safety hazards and fast battery fading, are huge barriers to commercialization. Herein, we used atomic layer deposition (ALD) to prepare conformal, ultrathin aluminum oxide coatings on lithium. We investigated the growth mechanism during Al 2O 3 ALD on lithium by in situ quartz crystal microbalance and found largermore » growth than expected during the initial cycles. We also discovered that the ALD Al 2O 3 enhances the wettability of the Li surface towards both carbonate and ether electrolytes, leading to uniform and dense SEI formation and reduced electrolyte consumption during battery operation. Scanning electron microscopy verified that the bare Li surfaces become rough and dendritic after electrochemical cycling, whereas the ALD Al 2O 3 coated Li surfaces remain smooth and uniform. Analysis of the Li surfaces after cycling using X-ray photoelectron spectroscopy and in situ transmission electron microscopy revealed that the ALD Al 2O 3 coating remains intact during electrochemical cycling, and that Li ions diffuse through the coating and deposit on the underlying Li. Coin cell testing demonstrated more than two times longer cycling life for the ALD Al 2O 3 protected Li, and a coulombic efficiency as high as ~98% at a practical current rate of 1 mA cm -2. More significantly, when the electrolyte volume was reduced from 20 to 5 μL, the stabilizing effect of the ALD coating became even more pronounced and the cycling life was around four times longer. Finally, these results indicate that ALD Al 2O 3 coatings are a promising strategy to stabilize Li anodes for high performance energy storage devices such as Li–S batteries.« less

Developmental stage-specific regulation of the circadian clock by temperature in zebrafish.

PubMed

Lahiri, Kajori; Froehlich, Nadine; Heyd, Andreas; Foulkes, Nicholas S; Vallone, Daniela

2014-01-01

The circadian clock enables animals to adapt their physiology and behaviour in anticipation of the day-night cycle. Light and temperature represent two key environmental timing cues (zeitgebers) able to reset this mechanism and so maintain its synchronization with the environmental cycle. One key challenge is to unravel how the regulation of the clock by zeitgebers matures during early development. The zebrafish is an ideal model for studying circadian clock ontogeny since the process of development occurs ex utero in an optically transparent chorion and many tools are available for genetic analysis. However, the role played by temperature in regulating the clock during zebrafish development is poorly understood. Here, we have established a clock-regulated luciferase reporter transgenic zebrafish line (Tg (-3.1) per1b::luc) to study the effects of temperature on clock entrainment. We reveal that under complete darkness, from an early developmental stage onwards (48 to 72 hpf), exposure to temperature cycles is a prerequisite for the establishment of self-sustaining rhythms of zfper1b, zfaanat2, and zfirbp expression and also for circadian cell cycle rhythms. Furthermore, we show that following the 5-9 somite stage, the expression of zfper1b is regulated by acute temperature shifts.

G1/S phase progression is regulated by PLK1 degradation through the CDK1/βTrCP axis.

PubMed

Giráldez, Servando; Galindo-Moreno, María; Limón-Mortés, M Cristina; Rivas, A Cristina; Herrero-Ruiz, Joaquín; Mora-Santos, Mar; Sáez, Carmen; Japón, Miguel Á; Tortolero, Maria; Romero, Francisco

2017-07-01

Polo-like kinase 1 (PLK1) is a serine/threonine kinase involved in several stages of the cell cycle, including the entry and exit from mitosis, and cytokinesis. Furthermore, it has an essential role in the regulation of DNA replication. Together with cyclin A, PLK1 also promotes CDH1 phosphorylation to trigger its ubiquitination and degradation, allowing cell cycle progression. The PLK1 levels in different type of tumors are very high compared to normal tissues, which is consistent with its role in promoting proliferation. Therefore, several PLK1 inhibitors have been developed and tested for the treatment of cancer. Here, we further analyzed PLK1 degradation and found that cytoplasmic PLK1 is ubiquitinated and subsequently degraded by the SCF βTrCP /proteasome. This procedure is triggered when heat shock protein (HSP) 90 is inhibited with geldanamycin, which results in misfolding of PLK1. We also identified CDK1 as the major kinase involved in this degradation. Our work shows for the first time that HSP90 inhibition arrests cell cycle progression at the G 1 /S transition. This novel mechanism inhibits CDH1 degradation through CDK1-dependent PLK1 destruction by the SCF βTrCP /proteasome. In these conditions, CDH1 substrates do not accumulate and cell cycle arrests, providing a novel pathway for regulation of the cell cycle at the G 1 -to-S boundary.-Giráldez, S., Galindo-Moreno, M., Limón-Mortés, M. C., Rivas, A. C., Herrero-Ruiz, J., Mora-Santos, M., Sáez, C., Japón, M. Á., Tortolero, M., Romero, F. G 1 /S phase progression is regulated by PLK1 degradation through the CDK1/βTrCP axis. © FASEB.

One-dimensional nanostructured materials for lithium-ion battery and supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Chan, Candace Kay

The need for improved electrochemical storage devices has necessitated research on new and advanced electrode materials. One-dimensional nanomaterials such as nanowires, nanotubes, and nanoribbons, can provide a unique opportunity to engineer electrochemical devices to have improved electronic and ionic conductivity as well as electrochemical and structural transformations. Silicon and germanium nanowires (NWs) were studied as negative electrode materials for lithiumion batteries because of their ability to alloy with large amounts of lithium, leading to 4-10 times higher specific capacities than the graphite standard. These nanowires could be grown vertically off of metallic current collector substrates using the gold-catalyzed vapor-liquid-solid synthesis. Electrochemical measurements of the SiNWs showed that capacities greater than 3,500 mAh/g could be obtained for tens of cycles, while hundreds of cycles could be obtained at lower capacities. As opposed to bulk Si, the SiNWs were observed to maintain their morphology during cycling and did not pulverize due to the large volume changes. Detailed TEM and XRD characterization showed that the SiNWs became amorphous during the first lithiation (charge) and formed a two-phase region between crystalline Si and amorphous Li xSi. Afterwards, the SiNWs remained amorphous and subsequent reaction was through a single-phase cycling of amorphous Si. The good cycling behavior compared to bulk and micron-sized Si particles was attributed to the nanowire morphology and electrode design. The surface chemistry and solid-electrolyte interphase (SEI) were studied using XPS as a function of charge and discharge potential. The common reduction productions expected in the electrolyte (1 M LiPF6 in 1:1 EC/DEC) were observed, with the main component being Li2CO3. The morphology of the SEI was found to change at different potentials, indicating a dynamic process involving deposition, dissolution, and re-deposition on the SiNWs. Longterm cycling performance of the SiNWs in different electrolytes, with various surface modifications and coatings, and other experimental parameters were evaluated. The electrochemical reaction of GeNWs with lithium resulted in capacities of ˜1000 mAh/g for tens of cycles. The GeNWs were also observed to become amorphous after the first charge. Interestingly, very large irreversible capacities were observed in the GeNWs, indicating surface instabilities or reactivity with the electrolyte. To passivate the surface, a thin layer of amorphous Si was used to coat the GeNWs and make Ge-Si coreshell nanowires. This passivation helped to reduce the irreversibly capacity loss and gave reversible capacities typical for the GeNWs. Two positive electrode materials for Li-ion batteries were synthesized in nano-morphologies and characterized. Transformation of layered structured V2O5 nanoribbons into the fully lithiated o-Li 3V2O5 phase was found to depend not only on the width but also the thickness of the nanoribbons. For the first time, complete delithiation of o-Li3V2O5 back to the single-crystalline, pristine V2O5 nanoribbon was observed, indicating a 30% higher energy density. Nanostructured BiOCl, a conversion material, was also synthesized and characterized for its Li insertion properties. Networks of silver nanowires (AgNWs) and single-walled carbon nanotubes (SWNTs) were explored as highly conducting, high surface area, and printable materials for flexible, light-weight supercapacitors. Use of the solution-processible AgNWs and SWNTs, as well as a polymer electrolyte, facilitated the fabrication of an entirely printable device on plastic substrates. The devices showed promising results for high energy and power density supercapacitors, with energy and power densities reaching 24 Wh/kg and 42 kW/kg for the AgNW/SWNT composite.

First-Principles Analysis of Defect Thermodynamics and Ion Transport in Inorganic SEI Compounds: LiF and NaF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yildirim, Handan; Kinaci, Alper; Chan, Maria K. Y.

The formation mechanism and composition of the solid electrolyte interphase (SEI) in lithium ion batteries has been widely explored. However, relatively little is known about the function of the SEI as a transport medium. Such critical information is directly relevant to battery rate performance, power loss, and capacity fading. To partially bridge this gap in the case of inorganic SEI compounds, we report herein the results of first-principles calculations on the defect thermodynamics, the dominant diffusion carriers, and the diffusion pathways associated with crystalline LiF and NaF, which are stable components of the SEI in Li-ion and Na-ion batteries, respectively.more » The thermodynamics of common point defects are computed, and the dominant diffusion carriers are determined over a voltage range of 0-4 V, corresponding to conditions relevant to both anode and cathode SEI's. Our analyses reveal that for both compounds, vacancy defects are energetically more favorable, therefore form more readily than interstitials, due to the close-packed nature of the crystal structures. However, the vacancy concentrations are very small for the diffusion processes facilitated by defects. Ionic conductivities are calculated as a function of voltage, considering the diffusion carrier concentration and the diffusion barriers as determined by nudged elastic band calculations. These conductivities are more than ten orders of magnitude smaller in NaF than in LiF. As compared to the diffusivity of Li in other common inorganic SEI compounds, such as Li2CO3 and Li2O,the cation diffusivity in LiF and NaF is quite low, with at least three orders of magnitude lower ionic conductivities. The results quantify the extent to which fluorides pose rate limitations in Li and Na batteries.« less

Insights into the Li Intercalation and SEI Formation on LiSi Nanoclusters

DOE PAGES

Hankins, Kie; Soto, Fernando A.; Balbuena, Perla B.

2017-01-01

We report a first-principles atomic level assessment of the lithiation and reactivity of pre-lithiated Si clusters. Density functional theory formation energy calculations reveal that the pre-lithiated Li 16Si 16 cluster exposed to two different Li fluxes can store Li between the concentrations of Li 2.5Si and Li 3.5Si. This increase in storage capacity is attributed to the start of an amorphization process in the cluster, and more importantly these results show that the intercalation reaction can be controlled by the flux of the Li-ions. However, in a real battery, the lithiation of the anode occurs simultaneously to the electrode-electrolyte reactions.more » Here we simulate the solid-electrolyte interphase (SEI) formation and simultaneous lithiation of a Li 16Si 16 cluster in contact with two different electrolyte solutions: one with pure ethylene carbonate (EC), and another with a 1 M solution of LiPF 6 in EC. Our ab initio molecular dynamics simulations show that the solvent and salt are decomposed leading to the initial stages of the SEI layer formation and large part of the added Li becomes part of the SEI. Interestingly, the pure EC solution results in lower storage capacity and higher reactivity, whereas the presence of the salt causes the opposite effect: higher lithiation and reduced reactivity.« less

Fra-1 promotes growth and survival in RAS-transformed thyroid cells by controlling cyclin A transcription

PubMed Central

Casalino, Laura; Bakiri, Latifa; Talotta, Francesco; Weitzman, Jonathan B; Fusco, Alfredo; Yaniv, Moshe; Verde, Pasquale

2007-01-01

Fra-1 is frequently overexpressed in epithelial cancers and implicated in invasiveness. We previously showed that Fra-1 plays crucial roles in RAS transformation in rat thyroid cells and mouse fibroblasts. Here, we report a novel role for Fra-1 as a regulator of mitotic progression in RAS-transformed thyroid cells. Fra-1 expression and phosphorylation are regulated during the cell cycle, peaking at G2/M. Knockdown of Fra-1 caused a proliferative block and apoptosis. Although most Fra-1-knockdown cells accumulated in G2, a fraction of cells entering M-phase underwent abortive cell division and exhibited hallmarks of genomic instability (micronuclei, lagging chromosomes and anaphase bridges). Furthermore, we established a link between Fra-1 and the cell-cycle machinery by identifying cyclin A as a novel transcriptional target of Fra-1. During the cell cycle, Fra-1 was recruited to the cyclin A gene (ccna2) promoter, binding to previously unidentified AP-1 sites and the CRE. Fra-1 also induced the expression of JunB, which in turn interacts with the cyclin A promoter. Hence, Fra-1 induction is important in thyroid tumorigenesis, critically regulating cyclin expression and cell-cycle progression. PMID:17347653

Transcriptome-wide analysis of the Trypanosoma cruzi proliferative cycle identifies the periodically expressed mRNAs and their multiple levels of control

PubMed Central

Chávez, Santiago; Eastman, Guillermo; Smircich, Pablo; Becco, Lorena Lourdes; Oliveira-Rizzo, Carolina; Fort, Rafael; Potenza, Mariana; Garat, Beatriz; Sotelo-Silveira, José Roberto

2017-01-01

Trypanosoma cruzi is the protozoan parasite causing American trypanosomiasis or Chagas disease, a neglected parasitosis with important human health impact in Latin America. The efficacy of current therapy is limited, and its toxicity is high. Since parasite proliferation is a fundamental target for rational drug design, we sought to progress into its understanding by applying a genome-wide approach. Treating a TcI linage strain with hydroxyurea, we isolated epimastigotes in late G1, S and G2/M cell cycle stages at 70% purity. The sequencing of each phase identified 305 stage-specific transcripts (1.5-fold change, p≤0.01), coding for conserved cell cycle regulated proteins and numerous proteins whose cell cycle dependence has not been recognized before. Comparisons with the parasite T. brucei and the human host reveal important differences. The meta-analysis of T. cruzi transcriptomic and ribonomic data indicates that cell cycle regulated mRNAs are subject to sub-cellular compartmentalization. Compositional and structural biases of these genes- including CAI, GC content, UTR length, and polycistron position- may contribute to their regulation. To discover nucleotide motifs responsible for the co-regulation of cell cycle regulated genes, we looked for overrepresented motifs at their UTRs and found a variant of the cell cycle sequence motif at the 3' UTR of most of the S and G2 stage genes. We additionally identified hairpin structures at the 5' UTRs of a high proportion of the transcripts, suggesting that periodic gene expression might also rely on translation initiation in T. cruzi. In summary, we report a comprehensive list of T. cruzi cell cycle regulated genes, including many previously unstudied proteins, we show evidence favoring a multi-step control of their expression, and we identify mRNA motifs that may mediate their regulation. Our results provide novel information of the T. cruzi proliferative proteins and the integrated levels of their gene expression control. PMID:29182646

Magnesium Hydride Nanoparticles Self-Assembled on Graphene as Anode Material for High-Performance Lithium-Ion Batteries.

PubMed

Zhang, Baoping; Xia, Guanglin; Sun, Dalin; Fang, Fang; Yu, Xuebin

2018-04-24

MgH 2 nanoparticles (NPs) uniformly anchored on graphene (GR) are fabricated based on a bottom-up self-assembly strategy as anode materials for lithium-ion batteries (LIBs). Monodisperse MgH 2 NPs with an average particle size of ∼13.8 nm are self-assembled on the flexible GR, forming interleaved MgH 2 /GR (GMH) composite architectures. Such nanoarchitecture could effectively constrain the aggregation of active materials, buffer the strain of volume changes, and facilitate the electron/lithium ion transfer of the whole electrode, leading to a significant enhancement of the lithium storage capacity of the GMH composite. Furthermore, the performances of GMH composite as anode materials for LIBs are enabled largely through robust interfacial interactions with poly(methyl methacrylate) (PMMA) binder, which plays multifunctional roles in forming a favorable solid-electrolyte interphase (SEI) film, alleviating the volume expansion and detachment of active materials, and maintaining the structural integrity of the whole electrode. As a result, these synergistic effects endow the obtained GMH composite with a significantly enhanced reversible capacity and cyclability as well as a good rate capability. The GMH composite with 50 wt % MgH 2 delivers a high reversible capacity of 946 mA h g -1 at 100 mA g -1 after 100 cycles and a capacity of 395 mAh g -1 at a high current density of 2000 mA g -1 after 1000 cycles.

p57KIP2 regulates radial glia and intermediate precursor cell cycle dynamics and lower layer neurogenesis in developing cerebral cortex

PubMed Central

Mairet-Coello, Georges; Tury, Anna; Van Buskirk, Elise; Robinson, Kelsey; Genestine, Matthieu; DiCicco-Bloom, Emanuel

2012-01-01

During cerebral cortex development, precise control of precursor cell cycle length and cell cycle exit is required for balanced precursor pool expansion and layer-specific neurogenesis. Here, we defined the roles of cyclin-dependent kinase inhibitor (CKI) p57KIP2, an important regulator of G1 phase, using deletion mutant mice. Mutant mice displayed macroencephaly associated with cortical hyperplasia during late embryogenesis and postnatal development. Embryonically, proliferation of radial glial cells (RGC) and intermediate precursors (IPC) was increased, expanding both populations, with greater effect on IPCs. Furthermore, cell cycle re-entry was increased during early corticogenesis, whereas cell cycle exit was augmented at middle stage. Consequently, neurogenesis was reduced early, whereas it was enhanced during later development. In agreement, the timetable of early neurogenesis, indicated by birthdating analysis, was delayed. Cell cycle dynamics analyses in mutants indicated that p57KIP2 regulates cell cycle length in both RGCs and IPCs. By contrast, related CKI p27KIP1 controlled IPC proliferation exclusively. Furthermore, p57KIP2 deficiency markedly increased RGC and IPC divisions at E14.5, whereas p27KIP1 increased IPC proliferation at E16.5. Consequently, loss of p57KIP2 increased primarily layer 5-6 neuron production, whereas loss of p27KIP1 increased neurons specifically in layers 2-5. In conclusion, our observations suggest that p57KIP2 and p27KIP1 control neuronal output for distinct cortical layers by regulating different stages of precursor proliferation, and support a model in which IPCs contribute to both lower and upper layer neuron generation. PMID:22223678

Inhibition of E2F1 activity and cell cycle progression by arsenic via retinoblastoma protein.

PubMed

Sheldon, Lynn A

2017-01-01

The regulation of cell cycle progression by steroid hormones and growth factors is important for maintaining normal cellular processes including development and cell proliferation. Deregulated progression through the G1/S and G2/M cell cycle transitions can lead to uncontrolled cell proliferation and cancer. The transcription factor E2F1, a key cell cycle regulator, targets genes encoding proteins that regulate cell cycle progression through the G1/S transition as well as proteins important in DNA repair and apoptosis. E2F1 expression and activity is inhibited by inorganic arsenic (iAs) that has a dual role as a cancer therapeutic and as a toxin that leads to diseases including cancer. An understanding of what underlies this dichotomy will contribute to understanding how to use iAs as a more effective therapeutic and also how to treat cancers that iAs promotes. Here, we show that quiescent breast adenocarcinoma MCF-7 cells treated with 17-β estradiol (E2) progress through the cell cycle, but few cells treated with E2 + iAs progress from G1 into S-phase due to a block in cell cycle progression. Our data support a model in which iAs inhibits the dissociation of E2F1 from the tumor suppressor, retinoblastoma protein (pRB) due to changes in pRB phosphorylation which leads to decreased E2F1 transcriptional activity. These findings present an explanation for how iAs can disrupt cell cycle progression through E2F1-pRB and has implications for how iAs acts as a cancer therapeutic as well as how it may promote tumorigenesis through decreased DNA repair.

In Situ Chemical Imaging of Solid-Electrolyte Interphase Layer Evolution in Li–S Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nandasiri, Manjula I.; Camacho-Forero, Luis E.; Schwarz, Ashleigh M.

Parasitic reactions of electrolyte and polysulfide with the Li-anode in lithium sulfur (Li-S) batteries lead to the formation of solid-electrolyte interphase (SEI) layers, which are the major reason behind severe capacity fading in these systems. Despite numerous studies, the evolution mechanism of the SEI layer and specific roles of polysulfides and other electrolyte components are still unclear. Here, we report an in-situ X-ray photoelectron spectroscopy (XPS) and chemical imaging analysis combined with ab initio molecular dynamics (AIMD) computational modeling to gain fundamental understanding regarding the evolution of SEI layers on Li-anodes within Li-S batteries. A multi-modal approach involving AIMD modelingmore » and in-situ XPS characterization uniquely reveals the chemical identity and distribution of active participants in parasitic reactions as well as the SEI layer evolution mechanism. The SEI layer evolution has three major stages: the formation of a primary composite mixture phase involving stable lithium compounds (Li 2S, LiF, Li 2O etc); and formation of a secondary matrix type phase due to cross interaction between reaction products and electrolyte components, which is followed by a highly dynamic mono-anionic polysulfide (i.e. LiS 5) fouling process. In conclusion, these new molecular-level insights into the SEI layer evolution on Li- anodes are crucial for delineating effective strategies for the development of Li–S batteries.« less

In Situ Chemical Imaging of Solid-Electrolyte Interphase Layer Evolution in Li–S Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nandasiri, Manjula I.; Camacho-Forero, Luis E.; Schwarz, Ashleigh M.

Parasitic reactions of electrolyte and polysulfide with the Li-anode in lithium sulfur (Li-S) batteries lead to the for-mation of solid electrolyte interphase (SEI) layers, which are the major reason behind severe capacity fading in these systems. Despite numerous studies, the evolution mechanism of the SEI layer and specific roles of polysulfides and oth-er electrolyte components are still unclear. We report an in-situ X-ray photoelectron spectroscopy (XPS) and chemical imaging analysis combined with ab initio molecular dynamics (AIMD) computational modeling to gain fundamental understanding regarding the evolution of SEI layers on Li-anodes within Li-S batteries. A multi-modal approach in-volving AIMD modelingmore » and in-situ XPS characterization uniquely reveals the chemical identity and distribution of active participants in parasitic reactions as well as the SEI layer evolution mechanism. The SEI layer evolution has three major stages: the formation of a primary composite mixture phase involving stable lithium compounds (Li2S, LiF, Li2O etc); and formation of a secondary matrix type phase due to cross interaction between reaction products and elec-trolyte components, which is followed by a highly dynamic mono-anionic polysulfide (i.e. LiS5) fouling process. These new molecular-level insights into the SEI layer evolution on Li- anodes are crucial for delineating effective strategies for the development of Li–S batteries.« less

SeisComP 3 - Where are we now?

NASA Astrophysics Data System (ADS)

Saul, Joachim; Becker, Jan; Hanka, Winfried; Heinloo, Andres; Weber, Bernd

2010-05-01

The seismological software SeisComP has evolved within the last approximately 10 years from a pure acquisition modules to a fully featured real-time earthquake monitoring software. The now very popular SeedLink protocol for seismic data transmission has been the core of SeisComP from the very beginning. Later additions included simple, purely automatic event detection, location and magnitude determination capabilities. Especially within the development of the 3rd-generation SeisComP, also known as "SeisComP 3", automatic processing capabilities have been augmented by graphical user interfaces for vizualization, rapid event review and quality control. Communication between the modules is achieved using a a TCP/IP infrastructure that allows distributed computing and remote review. For seismological metadata exchange export/import to/from QuakeML is avalable, which also provides a convenient interface with 3rd-party software. SeisComP is the primary seismological processing software at the GFZ Potsdam. It has also been in use for years in numerous seismic networks in Europe and, more recently, has been adopted as primary monitoring software by several tsunami warning centers around the Indian Ocean. In our presentation we describe the current status of development as well as future plans. We illustrate its possibilities by discussing different use cases for global and regional real-time earthquake monitoring and tsunami warning.

In Situ Chemical Imaging of Solid-Electrolyte Interphase Layer Evolution in Li–S Batteries

DOE PAGES

Nandasiri, Manjula I.; Camacho-Forero, Luis E.; Schwarz, Ashleigh M.; ...

2017-05-03

Parasitic reactions of electrolyte and polysulfide with the Li-anode in lithium sulfur (Li-S) batteries lead to the formation of solid-electrolyte interphase (SEI) layers, which are the major reason behind severe capacity fading in these systems. Despite numerous studies, the evolution mechanism of the SEI layer and specific roles of polysulfides and other electrolyte components are still unclear. Here, we report an in-situ X-ray photoelectron spectroscopy (XPS) and chemical imaging analysis combined with ab initio molecular dynamics (AIMD) computational modeling to gain fundamental understanding regarding the evolution of SEI layers on Li-anodes within Li-S batteries. A multi-modal approach involving AIMD modelingmore » and in-situ XPS characterization uniquely reveals the chemical identity and distribution of active participants in parasitic reactions as well as the SEI layer evolution mechanism. The SEI layer evolution has three major stages: the formation of a primary composite mixture phase involving stable lithium compounds (Li 2S, LiF, Li 2O etc); and formation of a secondary matrix type phase due to cross interaction between reaction products and electrolyte components, which is followed by a highly dynamic mono-anionic polysulfide (i.e. LiS 5) fouling process. In conclusion, these new molecular-level insights into the SEI layer evolution on Li- anodes are crucial for delineating effective strategies for the development of Li–S batteries.« less

40 CFR 86.1332-90 - Engine mapping procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines; Gaseous and Particulate Exhaust Test Procedures... maximum mapping speed per the following methodologies. (Note paragraph (d)(1) below.) (1) Otto-cycle engines. (i) For ungoverned engines using the transient operating cycle set forth in paragraph (f)(1) of...

Artificial solid electrolyte interphase to address the electrochemical degradation of silicon electrodes.

PubMed

Li, Juchuan; Dudney, Nancy J; Nanda, Jagjit; Liang, Chengdu

2014-07-09

Electrochemical degradation on silicon (Si) anodes prevents them from being successfully used in lithium (Li)-ion battery full cells. Unlike the case of graphite anodes, the natural solid electrolyte interphase (SEI) films generated from carbonate electrolytes do not self-passivate on Si, causing continuous electrolyte decomposition and loss of Li ions. In this work, we aim at solving the issue of electrochemical degradation by fabricating artificial SEI films using a solid electrolyte material, lithium phosphorus oxynitride (Lipon), which conducts Li ions and blocks electrons. For Si anodes coated with Lipon of 50 nm or thicker, a significant effect is observed in suppressing electrolyte decomposition, while Lipon of thinner than 40 nm has a limited effect. Ionic and electronic conductivity measurements reveal that the artificial SEI is effective when it is a pure ionic conductor, but electrolyte decomposition is only partially suppressed when the artificial SEI is a mixed electronic-ionic conductor. The critical thickness for this transition in conducting behavior is found to be 40-50 nm. This work provides guidance for designing artificial SEI films for high-capacity Li-ion battery electrodes using solid electrolyte materials.

Artificial Solid Electrolyte Interphase to Address the Electrochemical Degradation of Silicon Electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dudney, Nancy J; Nanda, Jagjit; Liang, Chengdu

2014-01-01

Electrochemical degradation on Si anodes prevents them from being successfully used in lithium-ion full cells. Unlike the case of graphite anodes, natural solid electrolyte interphase (SEI) films generated from carbonate electrolyte do not self-passivate on Si and causes continuous electrolyte decomposition. In this work we aim at solving the issue of electrochemical degradation by fabricating artificial SEI films using a solid electrolyte material, lithium phosphor oxynitride (Lipon), that conducts Li ions and blocks electrons. For Si anodes coated with Lipon of 50 nm or thicker, significant effect is observed in suppressing the electrolyte decomposition, while Lipon of thinner than 40more » nm has little effect. Ionic and electronic conductivity measurement reveals that the artificial SEI is effective when it is a pure ionic conductor, and the electrolyte decomposition is not suppressed when the artificial SEI is a mixed electronic-ionic conductor. The critical thickness for this transition in conducting behavior is found to be 40~50 nm. This work provides guidance for designing artificial SEI for high capacity lithium-ion battery electrodes using solid electrolyte materials.« less

Tris(trimethylsilyl) Phosphite as an Efficient Electrolyte Additive To Improve the Surface Stability of Graphite Anodes.

PubMed

Yim, Taeeun; Han, Young-Kyu

2017-09-27

Tris(trimethylsilyl) phosphite (TMSP) has received considerable attention as a functional additive for various cathode materials in lithium-ion batteries, but the effect of TMSP on the surface stability of a graphite anode has not been studied. Herein, we demonstrate that TMSP serves as an effective solid electrolyte interphase (SEI)-forming additive for graphite anodes in lithium-ion batteries (LIBs). TMSP forms SEI layers by chemical reactions between TMSP and a reductively decomposed ethylene carbonate (EC) anion, which is strikingly different from the widely known mechanism of the SEI-forming additives. TMSP is stable under cathodic polarization, but it reacts chemically with radical anion intermediates derived from the electrochemical reduction of the carbonate solvents to generate a stable SEI layer. These TMSP-derived SEI layers improve the interfacial stability of the graphite anode, resulting in a retention of 96.8% and a high Coulombic efficiency of 95.2%. We suggest the use of TMSP as a functional additive that effectively stabilizes solid electrolyte interfaces of both the anode and cathode in lithium-ion batteries.

Structure of spontaneously formed solid-electrolyte interphase on lithiated graphite determined using small-angle neutron scattering

DOE PAGES

Sacci, Robert L.; Banuelos, Jose Leobardo; Veith, Gabriel M.; ...

2015-03-25

We report the first small-angle neutron scattering of a chemically formed solid-electrolyte interphase from LixC6 reacting with ethylene carbonate/dimethyl carbon solvent. This provides a different and perhaps simpler view of SEI formation than the usual electrochemically-driven reaction. We show that an organic layer coats the graphite particles filling in micro-pores and is polymeric in nature being 1-3 nm thick. We used inelastic neutron scattering to probe the chemistry, and we found that the SEI showed similar inelastic scattering to polyethylene oxide.

The Forkhead transcription factor Hcm1 regulates chromosome segregation genes and fills the S-phase gap in the transcriptional circuitry of the cell cycle.

PubMed

Pramila, Tata; Wu, Wei; Miles, Shawna; Noble, William Stafford; Breeden, Linda L

2006-08-15

Transcription patterns shift dramatically as cells transit from one phase of the cell cycle to another. To better define this transcriptional circuitry, we collected new microarray data across the cell cycle of budding yeast. The combined analysis of these data with three other cell cycle data sets identifies hundreds of new highly periodic transcripts and provides a weighted average peak time for each transcript. Using these data and phylogenetic comparisons of promoter sequences, we have identified a late S-phase-specific promoter element. This element is the binding site for the forkhead protein Hcm1, which is required for its cell cycle-specific activity. Among the cell cycle-regulated genes that contain conserved Hcm1-binding sites, there is a significant enrichment of genes involved in chromosome segregation, spindle dynamics, and budding. This may explain why Hcm1 mutants show 10-fold elevated rates of chromosome loss and require the spindle checkpoint for viability. Hcm1 also induces the M-phase-specific transcription factors FKH1, FKH2, and NDD1, and two cell cycle-specific transcriptional repressors, WHI5 and YHP1. As such, Hcm1 fills a significant gap in our understanding of the transcriptional circuitry that underlies the cell cycle.

Cutaway of SEIS (Artist's Concept)

NASA Image and Video Library

2018-04-09

This artist's rendering shows a cutaway of the Seismic Experiment for Interior Structure instrument, or SEIS, which will fly as part of NASA's Mars InSight lander. SEIS is a highly sensitive seismometer that will be used to detect marsquakes from the Red Planet's surface for the first time. There are two layers in this cutaway. The outer layer is the Wind and Thermal Shield -- a covering that protects the seismometer from the Martian environment. The wind on Mars, as well as extreme temperature changes, could affect the highly sensitive instrument. The inside layer is SEIS itself, a brass-colored dome that houses the instrument's three pendulums. These insides are inside a titanium vacuum chamber to further isolate them from temperature changes on the Martian surface. https://photojournal.jpl.nasa.gov/catalog/PIA22320

Epigenetic silencing of miR-218 by the lncRNA CCAT1, acting via BMI1, promotes an altered cell cycle transition in the malignant transformation of HBE cells induced by cigarette smoke extract

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Lu; Xu, Hui; Luo, Fei

Cigarette smoking is the strongest risk factor for the development of lung cancer, the leading cause of cancer-related deaths. However, the molecular mechanisms leading to lung cancer are largely unknown. A long-noncoding RNA (lncRNA), CCAT1, regarded as cancer-associated, has been investigated extensively. Moreover, the molecular mechanisms of lncRNAs in regulation of microRNAs (miRNAs) induced by cigarette smoke remain unclear. In the present investigation, cigarette smoke extract (CSE) caused an altered cell cycle and increased CCAT1 levels and decreased miR-218 levels in human bronchial epithelial (HBE) cells. Depletion of CCAT1 attenuated the CSE-induced decreases of miR-218 levels, suggesting that miR-218 ismore » negatively regulated by CCAT1 in HBE cells exposed to CSE. The CSE-induced increases of BMI1 levels and blocked by CCAT1 siRNA were attenuated by an miR-218 inhibitor. Moreover, in CSE-transformed HBE cells, the CSE-induced cell cycle changes and elevated neoplastic capacity were reversed by CCAT1 siRNA or BMI1 siRNA. This epigenetic silencing of miR-218 by CCAT1 induces an altered cell cycle transition through BMI1 and provides a new mechanism for CSE-induced lung carcinogenesis. - Highlights: • CSE exposure induces increases of CCAT1 levels and decreases of miR-218 levels. • CCAT1 negatively regulates miR-218 expression. • CCAT1, regulated by miR-218, via BMI1, is involved in the CSE-induced altered cell cycle transition.« less

Antitumorigenic effect of atmospheric-pressure dielectric barrier discharge on human colorectal cancer cells via regulation of Sp1 transcription factor

NASA Astrophysics Data System (ADS)

Han, Duksun; Cho, Jin Hyoung; Lee, Ra Ham; Bang, Woong; Park, Kyungho; Kim, Minseok S.; Shim, Jung-Hyun; Chae, Jung-Il; Moon, Se Youn

2017-02-01

Human colorectal cancer cell lines (HT29 and HCT116) were exposed to dielectric barrier discharge (DBD) plasma at atmospheric pressure to investigate the anticancer capacity of the plasma. The dose- and time-dependent effects of DBDP on cell viability, regulation of transcription factor Sp1, cell-cycle analysis, and colony formation were investigated by means of MTS assay, DAPI staining, propidium iodide staining, annexin V-FITC staining, Western blot analysis, RT-PCR analysis, fluorescence microscopy, and anchorage-independent cell transformation assay. By increasing the duration of plasma dose times, significant reductions in the levels of both Sp1 protein and Sp1 mRNA were observed in both cell lines. Also, expression of negative regulators related to the cell cycle (such as p53, p21, and p27) was increased and of the positive regulator cyclin D1 was decreased, indicating that the plasma treatment led to apoptosis and cell-cycle arrest. In addition, the sizes and quantities of colony formation were significantly suppressed even though two cancer promoters, such as TPA and epidermal growth factor, accompanied the plasma treatment. Thus, plasma treatment inhibited cell viability and colony formation by suppressing Sp1, which induced apoptosis and cell-cycle arrest in these two human colorectal cancer cell lines.

Interaction of FeS 2 and Sulfur in Li-S Battery System

DOE PAGES

Sun, Ke; Cama, Christina A.; DeMayo, Rachel A.; ...

2016-09-09

Many transition metal sulfides are electronically conductive, electrochemically active and reversible in reactions with lithium. However, the application of transition metal sulfides as sulfur cathode additives in lithium-sulfur (Li-S) batteries has not been fully explored. In this study, Pyrite (FeS 2) is studied as a capacity contributing conductive additive in sulfur cathode for Li-S batteries. Electrochemically discharging the S-FeS 2 composite electrodes to 1.0 V activates the FeS 2 component, contributing to the improved Li-S cell discharge energy density. However, direct activation of the FeS 2 component in a fresh S-FeS 2 cell results in a significant shuttling effect inmore » the subsequent charging process, preventing further cell cycling. The slight FeS 2 solubility in electrolyte and its activation alone in S-FeS 2 cells are not the root causes of the severe shuttling effect. The observed severe shuttling effect is strongly correlated to the 1st charging of the activated S-FeS 2 electrode that promotes iron dissolution in electrolyte and the deposition of electronically conductive FeS on the anode SEI. Pre-cycling of the S-FeS 2 cell prior to the FeS 2 activation or the use of LiNO 3 electrolyte additive help to prevent the severe shuttling effect and allow the cell to cycle between 2.6 V to 1.0 V with an extra capacity contribution from the FeS2 components. However, a more effective method of anode pre-passivation is still needed to fully protect the lithium surface from FeS deposition and allow the S-FeS 2 electrode to maintain high energy density over extended cycles. A mechanism explaining the observed phenomena based on the experimental data is proposed and discussed« less

Potential System Integration Issues in the Joint Multi-Role (JMR) Joint Common Architecture (JCA) Demonstration System

DTIC Science & Technology

2015-12-01

the MIS System/Subsystem Specification ( SSS ), and supplementary BAA document. On June 26, 2014, the SEI provided a draft interim report of the...findings and issues. The SEI team also received July 3, 2014, versions of the MIS Stakeholder Requirements, MIS SSS , and build plan and July 17, 2014...versions of the MIS SSS together with the MIS system model. On July 14–15, 2014, the SEI presented a summary of the issues at the two contractors

Global Identification of New Substrates for the Yeast Endoribonuclease, RNase Mitochondrial RNA Processing (MRP)*

PubMed Central

Aulds, Jason; Wierzbicki, Sara; McNairn, Adrian; Schmitt, Mark E.

2012-01-01

RNase mitochondrial RNA processing (MRP) is an essential, evolutionarily conserved endoribonuclease composed of 10 different protein subunits and a single RNA. RNase MRP has established roles in multiple pathways including ribosome biogenesis, cell cycle regulation, and mitochondrial DNA replication. Although each of these functions is important to cell growth, additional functions may exist given the essential nature of the complex. To identify novel RNase MRP substrates, we utilized RNA immunoprecipitation and microarray chip analysis to identify RNA that physically associates with RNase MRP. We identified several new potential substrates for RNase MRP including a cell cycle-regulated transcript, CTS1; the yeast homolog of the mammalian p27Kip1, SIC1; and the U2 RNA component of the spliceosome. In addition, we found RNase MRP to be involved in the regulation of the Ty1 transposon RNA. These results reinforce and broaden the role of RNase MRP in cell cycle regulation and help to identify new roles of this endoribonuclease. PMID:22977255

Global identification of new substrates for the yeast endoribonuclease, RNase mitochondrial RNA processing (MRP).

PubMed

Aulds, Jason; Wierzbicki, Sara; McNairn, Adrian; Schmitt, Mark E

2012-10-26

RNase mitochondrial RNA processing (MRP) is an essential, evolutionarily conserved endoribonuclease composed of 10 different protein subunits and a single RNA. RNase MRP has established roles in multiple pathways including ribosome biogenesis, cell cycle regulation, and mitochondrial DNA replication. Although each of these functions is important to cell growth, additional functions may exist given the essential nature of the complex. To identify novel RNase MRP substrates, we utilized RNA immunoprecipitation and microarray chip analysis to identify RNA that physically associates with RNase MRP. We identified several new potential substrates for RNase MRP including a cell cycle-regulated transcript, CTS1; the yeast homolog of the mammalian p27(Kip1), SIC1; and the U2 RNA component of the spliceosome. In addition, we found RNase MRP to be involved in the regulation of the Ty1 transposon RNA. These results reinforce and broaden the role of RNase MRP in cell cycle regulation and help to identify new roles of this endoribonuclease.

Evaluation of the telephone intervention in the promotion of diabetes self-care: a randomized clinical trial.

PubMed

Fernandes, Bárbara Sgarbi Morgan; Reis, Ilka Afonso; Torres, Heloisa de Carvalho

2016-08-29

to evaluate the effectiveness of the telephone intervention for promoting self-care related to physical activity and following a diet plan in users with diabetes, compared to conventional monitoring of users over a six-month period. this was a randomized clinical trial, which included 210 users with diabetes, linked to eight Primary Health Units of Belo Horizonte, Minas Gerais. The experimental group (104 members) received six telephone interventions over the six-month monitoring; the control group (106 members) received conventional monitoring. To evaluate the self-care practices related to physical activity and following a healthy eating plan, in both groups, the self-care questionnaire was applied before the intervention and at three and six months after its start. the mean effect of self-care scores in the experimental group was 1.03 to 1.78 higher than the control group, with progressive and significant improvement (p<0.001). the results indicate that the telephone intervention had a beneficial effect on diabetes self-care. The primary identifier of the clinical trials registry was: RBR-8wx7qb. avaliar a efetividade da intervenção telefônica na promoção do autocuidado relacionado à atividade física e ao seguimento de um plano alimentar, em usuários com diabetes, quando comparada ao acompanhamento convencional dos usuários, durante o período de seis meses. trata-se de um ensaio clínico randomizado, no qual participaram 210 usuários com diabetes, vinculados a oito Unidades Básicas de Saúde de Belo Horizonte, Minas Gerais. O grupo-experimental (104 usuários) recebeu seis intervenções telefônicas em seis meses de acompanhamento; o grupo-controle (106 usuários) recebeu acompanhamento convencional. Para avaliar as práticas de autocuidado, relacionada à atividade física e ao seguimento do plano alimentar saudável, em ambos os grupos, aplicou-se o questionário de autocuidado antes das intervenções, três e seis meses após o seu início. o efeito médio dos escores de autocuidado no grupo-experimental a pontuação foi de 1,03 a 1,78 maior do que o grupo-controle, apresentando melhora progressiva e significativa (valor-p<0,001). os resultados apontam que a intervenção telefônica tem efeito benéfico sobre o autocuidado em diabetes. O registro clínico obteve identificador primário: RBR-8wx7qb. evaluar la efectividad de la intervención telefónica en la promoción del autocuidado relacionado a la actividad física y al seguimiento de un plan alimentario, en usuarios con diabetes, cuando comparada al acompañamiento convencional de los usuarios, durante el período de seis meses. se trata de un ensayo clínico aleatorio, en el cual participaron 210 usuarios con diabetes, vinculados a ocho Unidades Básicas de la Salud de Belo Horizonte, Minas Gerais. El grupo experimental (104 usuarios) recibió seis intervenciones telefónicas en seis meses de acompañamiento; el grupo control (106 usuarios) recibió acompañamiento convencional. Para evaluar las prácticas de autocuidado, relacionadas a la actividad física y al seguimiento del plan alimentario saludable, en los dos grupos, se aplicó el cuestionario de autocuidado antes de las intervenciones, tres y seis meses después de su inicio. el efecto promedio de los puntajes de autocuidado en el grupo experimental fue de 1,03 a 1,78 mayor que el grupo control, presentando mejoría progresiva y significativa (valor-p<0,001). los resultados apuntan que la intervención telefónica tiene efecto benéfico sobre el autocuidado en diabetes. El registro clínico obtuvo identificador primario: RBR-8wx7qb.

Altered Body Weight Regulation in CK1ε Null and tau Mutant Mice on Regular Chow and High Fat Diets

PubMed Central

Zhou, Lili; Summa, Keith C.; Olker, Christopher; Vitaterna, Martha H.; Turek, Fred W.

2016-01-01

Disruption of circadian rhythms results in metabolic dysfunction. Casein kinase 1 epsilon (CK1ε) is a canonical circadian clock gene. Null and tau mutations in CK1ε show distinct effects on circadian period. To investigate the role of CK1ε in body weight regulation under both regular chow (RC) and high fat (HF) diet conditions, we examined body weight on both RC and HF diets in CK1ε −/− and CK1ε tau/tau mice on a standard 24 hr light-dark (LD) cycle. Given the abnormal entrainment of CK1ε tau/tau mice on a 24 hr LD cycle, a separate set of CK1ε tau/tau mice were tested under both diet conditions on a 20 hr LD cycle, which more closely matches their endogenous period length. On the RC diet, both CK1ε −/− and CK1ε tau/tau mutants on a 24 hr LD cycle and CK1ε tau/tau mice on a 20 hr LD cycle exhibited significantly lower body weights, despite similar overall food intake and activity levels. On the HF diet, CK1ε tau/tau mice on a 20 hr LD cycle were protected against the development of HF diet-induced excess weight gain. These results provide additional evidence supporting a link between circadian rhythms and energy regulation at the genetic level, particularly highlighting CK1ε involved in the integration of circadian biology and metabolic physiology. PMID:27144030

Ubiquitin specific protease 2 acts as a key modulator for the regulation of cell cycle by adiponectin and leptin in cancer cells.

PubMed

Nepal, Saroj; Shrestha, Anup; Park, Pil-Hoon

2015-09-05

Adiponectin and leptin, both produced from adipose tissue, cause cell cycle arrest and progression, respectively in cancer cells. Ubiquitin specific protease-2 (USP-2), a deubiquitinating enzyme, is known to impair proteasome-induced degradation of cyclin D1, a critical cell cycle regulator. Herein, we investigated the effects of these adipokines on USP-2 expression and its potential role in the modulation of cell cycle. Treatment with globular adiponectin (gAcrp) decreased, whereas leptin increased USP-2 expression both in human hepatoma and breast cancer cells. In addition, overexpression or gene silencing of USP-2 affected cyclin D1 expression and cell cycle progression/arrest by adipokines. Adiponectin and leptin also modulated in vitro proteasomal activity, which was partially dependent on USP-2 expression. Taken together, our results reveal that modulation of USP-2 expression plays a crucial role in cell cycle regulation by adipokines. Thus, USP-2 would be a promising therapeutic target for the modulation of cancer cell growth by adipokines. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

The APC/C Coordinates Retinal Differentiation with G1 Arrest through the Nek2-Dependent Modulation of Wingless Signaling.

PubMed

Martins, Torcato; Meghini, Francesco; Florio, Francesca; Kimata, Yuu

2017-01-09

The cell cycle is coordinated with differentiation during animal development. Here we report a cell-cycle-independent developmental role for a master cell-cycle regulator, the anaphase-promoting complex or cyclosome (APC/C), in the regulation of cell fate through modulation of Wingless (Wg) signaling. The APC/C controls both cell-cycle progression and postmitotic processes through ubiquitin-dependent proteolysis. Through an RNAi screen in the developing Drosophila eye, we found that partial APC/C inactivation severely inhibits retinal differentiation independently of cell-cycle defects. The differentiation inhibition coincides with hyperactivation of Wg signaling caused by the accumulation of a Wg modulator, Drosophila Nek2 (dNek2). The APC/C degrades dNek2 upon synchronous G1 arrest prior to differentiation, which allows retinal differentiation through local suppression of Wg signaling. We also provide evidence that decapentaplegic signaling may posttranslationally regulate this APC/C function. Thus, the APC/C coordinates cell-fate determination with the cell cycle through the modulation of developmental signaling pathways. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Mammalian Homologs of Yeast Checkpoint Genes

DTIC Science & Technology

2002-07-01

pathway is sensitive to various forms of DNA damage Developmental Biology throughout the cell cycle . The DNA replication check- Yale University point...components would be ordered into pathways for mammalian checkpoint function, with emphasis on p53 regulation, cell cycle regulation, and complementation...structurally related to the human tumor suppressor ATM. MEC1 and RAD53, two essential genes, play a central role in DNA damage checkpoints at all cell cycle

Non-DBS DNA Repair Genes Regulate Radiation-induced Cytogenetic Damage Repair and Cell Cycle Progression

NASA Technical Reports Server (NTRS)

Zhang, Ye; Rohde, Larry H.; Emami, Kamal; Casey, Rachael; Wu, Honglu

2008-01-01

Changes of gene expression profile are one of the most important biological responses in living cells after ionizing radiation (IR) exposure. Although some studies have shown that genes up-regulated by IR may play important roles in DNA damage repair, the relationship between the regulation of gene expression by IR, particularly genes not known for their roles in DSB repair, and its impact on cytogenetic responses has not been systematically studied. In the present study, the expression of 25 genes selected on the basis of their transcriptional changes in response to IR was individually knocked down by transfection with small interfering RNA in human fibroblast cells. The purpose of this study is to identify new roles of these selected genes on regulating DSB repair and cell cycle progression , as measured in the micronuclei formation and chromosome aberration. In response to IR, the formation of MN was significantly increased by suppressed expression of 5 genes: Ku70 in the DSB repair pathway, XPA in the NER pathway, RPA1 in the MMR pathway, and RAD17 and RBBP8 in cell cycle control. Knocked-down expression of 4 genes (MRE11A, RAD51 in the DSB pathway, SESN1, and SUMO1) significantly inhibited cell cycle progression, possibly because of severe impairment of DNA damage repair. Furthermore, loss of XPA, P21, or MLH1 expression resulted in both significantly enhanced cell cycle progression and increased yields of chromosome aberrations, indicating that these gene products modulate both cell cycle control and DNA damage repair. Most of the 11 genes that affected cytogenetic responses are not known to have clear roles influencing DBS repair. Nine of these 11 genes were up-regulated in cells exposed to gamma radiation, suggesting that genes transcriptionally modulated by IR were critical to regulate the biological consequences after IR.

Two Geminin homologs regulate DNA replication in silkworm, Bombyx mori.

PubMed

Tang, Xiao-Fang; Chen, Xiang-Yun; Zhang, Chun-Dong; Li, Yao-Feng; Liu, Tai-Hang; Zhou, Xiao-Lin; Wang, La; Zhang, Qian; Chen, Peng; Lu, Cheng; Pan, Min-Hui

2017-05-03

DNA replication is rigorously controlled in cells to ensure that the genome duplicates exactly once per cell cycle. Geminin is a small nucleoprotein, which prevents DNA rereplication by directly binding to and inhibiting the DNA replication licensing factor, Cdt1. In this study, we have identified 2 Geminin genes, BmGeminin1 and BmGeminn2, in silkworm, Bombyx mori. These genes contain the Geminin conserved coiled-coil domain and are periodically localized in the nucleus during the S-G2 phase but are degraded at anaphase in mitosis. Both BmGeminin1 and BmGeminin2 are able to homodimerize and interact with BmCdt1 in cells. In addition, BmGeminin1 and BmGeminin2 can interact with each other. Overexpression of BmGeminin1 affects cell cycle progression: cell cycle is arrested in S phase, and RNA interference of BmGeminin1 leads to rereplication. In contrast, overexpression or knockdown of BmGeminin2 with RNAi did not significantly affect cell cycle, while more rereplication occurred when BmGeminin1 and BmGeminin2 together were knocked down in cells than when only BmGeminin1 was knocked down. These data suggest that both BmGeminin1 and BmGeminin2 are involved in the regulation of DNA replication. These findings provide insight into the function of Geminin and contribute to our understanding of the regulation mechanism of cell cycle in silkworm.

The Adder Phenomenon Emerges from Independent Control of Pre- and Post-Start Phases of the Budding Yeast Cell Cycle.

PubMed

Chandler-Brown, Devon; Schmoller, Kurt M; Winetraub, Yonatan; Skotheim, Jan M

2017-09-25

Although it has long been clear that cells actively regulate their size, the molecular mechanisms underlying this regulation have remained poorly understood. In budding yeast, cell size primarily modulates the duration of the cell-division cycle by controlling the G1/S transition known as Start. We have recently shown that the rate of progression through Start increases with cell size, because cell growth dilutes the cell-cycle inhibitor Whi5 in G1. Recent phenomenological studies in yeast and bacteria have shown that these cells add an approximately constant volume during each complete cell cycle, independent of their size at birth. These results seem to be in conflict, as the phenomenological studies suggest that cells measure the amount they grow, rather than their size, and that size control acts over the whole cell cycle, rather than specifically in G1. Here, we propose an integrated model that unifies the adder phenomenology with the molecular mechanism of G1/S cell-size control. We use single-cell microscopy to parameterize a full cell-cycle model based on independent control of pre- and post-Start cell-cycle periods. We find that our model predicts the size-independent amount of cell growth during the full cell cycle. This suggests that the adder phenomenon is an emergent property of the independent regulation of pre- and post-Start cell-cycle periods rather than the consequence of an underlying molecular mechanism measuring a fixed amount of growth. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cell cycle regulation in Schizosaccharomyces pombe.

PubMed

Moser, B A; Russell, P

2000-12-01

Cdc2, a cyclin-dependent kinase, controls cell cycle progression in fission yeast. New details of Cdc2 regulation and function have been uncovered in recent studies. These studies involve cyclins that associate with Cdc2 in G1-phase and the proteins that regulate inhibitory phosphorylation of Cdc2 during S-phase and G2-phase. Recent investigations have also provided a better understanding of proteins that regulate DNA replication and that are directly or indirectly controlled by Cdc2.

CCS52A2/FZR1, a cell cycle regulator, is an essential factor for shoot apical meristem maintenance in Arabidopsis thaliana.

PubMed

Liu, Yajie; Ye, Wei; Li, Beibei; Zhou, Xiaojing; Cui, Yuhai; Running, Mark P; Liu, Kede

2012-08-08

Cell division and cell fate decisions regulate organ formation and function in plant growth and development. It is still unclear how specific meristematic regulatory networks operate with the cell cycle machinery to translate stem cell identity and maintenance into cellular behavior. In this study, we address these questions by analysis of a shoot apex defective mutant, namely xcm9. Phenotypic analysis of the xcm9 mutant reveals concomitant premature termination of floral shoots with frequent bifurcation of the shoot apices, stems, and flowers. Microscopic observations show irregular cell organization in shoot apical meristems of xcm9. Positional cloning revealed that xcm9 is a loss of function allele of the CCS52A2/FZR1 gene, which has previously been implicated in root development. Expression analysis demonstrated that CCS52A2 maintains a higher transcriptional expression level in actively dividing tissue. Genetic studies indicated that the CCS52A2 gene functions together with WUSCHEL (WUS) and CLAVATA3 (CLV3) in regulating the development of the shoot meristem, and also contributes to this regulation together with the chromatin remodeling pathway. In addition, fewer xcm9 cells express CYCLIN B1:1, showing that cell cycle progression is disrupted in the mutant. We propose that the CCS52A2 gene is a mediator that functions together with meristematic genes to regulate meristem organization, and cross-functions with chromatin regulators in cell cycle progression during shoot apical meristem development.

Role of additives in formation of solid-electrolyte interfaces on carbon electrodes and their effect on high-voltage stability.

PubMed

Qu, Weiguo; Dorjpalam, Enkhtuvshin; Rajagopalan, Ramakrishnan; Randall, Clive A

2014-04-01

The in situ modification of a lithium hexafluorophosphate-based electrolyte using a molybdenum oxide catalyst and small amount of water (1 vol %) yields hydrolysis products such as mono-, di-, and alkylfluorophosphates. The electrochemical stability of ultrahigh-purity, high-surface-area carbon electrodes derived from polyfurfuryl alcohol was tested using the modified electrolyte. Favorable modification of the solid electrolyte interface (SEI) layer on the activated carbon electrode increased the cyclable electrochemical voltage window (4.8-1.2 V vs. Li/Li(+)). The chemical modification of the SEI layer induced by electrolyte additives was characterized by using X-ray photoelectron spectroscopy. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

AS160 controls eukaryotic cell cycle and proliferation by regulating the CDK inhibitor p21.

PubMed

Gongpan, Pianchou; Lu, Yanting; Wang, Fang; Xu, Yuhui; Xiong, Wenyong

2016-07-02

AS160 (TBC1D4) has been implicated in multiple biological processes. However, the role and the mechanism of action of AS160 in the regulation of cell proliferation remain unclear. In this study, we demonstrated that AS160 knockdown led to blunted cell proliferation in multiple cell types, including fibroblasts and cancer cells. The results of cell cycle analysis showed that these cells were arrested in the G1 phase. Intriguingly, this inhibition of cell proliferation and the cell cycle arrest caused by AS160 depletion were glucose independent. Moreover, AS160 silencing led to a marked upregulation of the expression of the cyclin-dependent kinase inhibitor p21. Furthermore, whereas AS160 overexpression resulted in p21 downregulation and rescued the arrested cell cycle in AS160-depeleted cells, p21 silencing rescued the inhibited cell cycle and proliferation in the cells. Thus, our results demonstrated that AS160 regulates glucose-independent eukaryotic cell proliferation through p21-dependent control of the cell cycle, and thereby revealed a molecular mechanism of AS160 modulation of cell cycle and proliferation that is of general physiological significance.

Dynamics of Human Telomerase Holoenzyme Assembly and Subunit Exchange across the Cell Cycle*

PubMed Central

Vogan, Jacob M.; Collins, Kathleen

2015-01-01

Human telomerase acts on telomeres during the genome synthesis phase of the cell cycle, accompanied by its concentration in Cajal bodies and transient colocalization with telomeres. Whether the regulation of human telomerase holoenzyme assembly contributes to the cell cycle restriction of telomerase function is unknown. We investigated the steady-state levels, assembly, and exchange dynamics of human telomerase subunits with quantitative in vivo cross-linking and other methods. We determined the physical association of telomerase subunits in cells blocked or progressing through the cell cycle as synchronized by multiple protocols. The total level of human telomerase RNA (hTR) was invariant across the cell cycle. In vivo snapshots of telomerase holoenzyme composition established that hTR remains bound to human telomerase reverse transcriptase (hTERT) throughout all phases of the cell cycle, and subunit competition assays suggested that hTERT-hTR interaction is not readily exchangeable. In contrast, the telomerase holoenzyme Cajal body-associated protein, TCAB1, was released from hTR in mitotic cells coincident with TCAB1 delocalization from Cajal bodies. This telomerase holoenzyme disassembly was reversible with cell cycle progression without any change in total TCAB1 protein level. Consistent with differential cell cycle regulation of hTERT-hTR and TCAB1-hTR protein-RNA interactions, overexpression of hTERT or TCAB1 had limited if any influence on hTR assembly of the other subunit. Overall, these findings revealed a cell cycle regulation that disables human telomerase association with telomeres while preserving the co-folded hTERT-hTR ribonucleoprotein catalytic core. Studies here, integrated with previous work, led to a unifying model for telomerase subunit assembly and trafficking in human cells. PMID:26170453

A Transcriptome-based Perspective of Cell Cycle Regulation in Dinoflagellates.

PubMed

Morse, David; Daoust, Philip; Benribague, Siham

2016-12-01

Dinoflagellates are a group of unicellular and generally marine protists, of interest to many because of their ability to form the large algal blooms commonly called "red tides". The large algal concentrations in these blooms require sustained cell replication, yet to date little is known about cell cycle regulation in these organisms. To address this issue, we have screened the transcriptomes of two dinoflagellates, Lingulodinium polyedrum and Symbiodinium sp., with budding yeast cell cycle pathway components. We find most yeast cell cycle regulators have homologs in these dinoflagellates, suggesting that the yeast model is appropriate for understanding regulation of the dinoflagellate cell cycle. The dinoflagellates are lacking several components essential in yeast, but a comparison with a broader phylogenetic range of protists reveals these components are usually also missing in other organisms. Lastly, phylogenetic analyses show that the dinoflagellates contain at least three cyclin-dependent kinase (CDK) homologs (belonging to the CDK1, CDK5 and CDK8 families), and that the dinoflagellate cyclins belong exclusively to the A/B type. This suggests that dinoflagellate CDKs likely play a limited role outside regulation of the cell cycle. Copyright © 2016 Elsevier GmbH. All rights reserved.

Regulation of a transcription factor network by Cdk1 coordinates late cell cycle gene expression

PubMed Central

Landry, Benjamin D; Mapa, Claudine E; Arsenault, Heather E; Poti, Kristin E; Benanti, Jennifer A

2014-01-01

To maintain genome stability, regulators of chromosome segregation must be expressed in coordination with mitotic events. Expression of these late cell cycle genes is regulated by cyclin-dependent kinase (Cdk1), which phosphorylates a network of conserved transcription factors (TFs). However, the effects of Cdk1 phosphorylation on many key TFs are not known. We find that elimination of Cdk1-mediated phosphorylation of four S-phase TFs decreases expression of many late cell cycle genes, delays mitotic progression, and reduces fitness in budding yeast. Blocking phosphorylation impairs degradation of all four TFs. Consequently, phosphorylation-deficient mutants of the repressors Yox1 and Yhp1 exhibit increased promoter occupancy and decreased expression of their target genes. Interestingly, although phosphorylation of the transcriptional activator Hcm1 on its N-terminus promotes its degradation, phosphorylation on its C-terminus is required for its activity, indicating that Cdk1 both activates and inhibits a single TF. We conclude that Cdk1 promotes gene expression by both activating transcriptional activators and inactivating transcriptional repressors. Furthermore, our data suggest that coordinated regulation of the TF network by Cdk1 is necessary for faithful cell division. PMID:24714560

Regulation of a transcription factor network by Cdk1 coordinates late cell cycle gene expression.

PubMed

Landry, Benjamin D; Mapa, Claudine E; Arsenault, Heather E; Poti, Kristin E; Benanti, Jennifer A

2014-05-02

To maintain genome stability, regulators of chromosome segregation must be expressed in coordination with mitotic events. Expression of these late cell cycle genes is regulated by cyclin-dependent kinase (Cdk1), which phosphorylates a network of conserved transcription factors (TFs). However, the effects of Cdk1 phosphorylation on many key TFs are not known. We find that elimination of Cdk1-mediated phosphorylation of four S-phase TFs decreases expression of many late cell cycle genes, delays mitotic progression, and reduces fitness in budding yeast. Blocking phosphorylation impairs degradation of all four TFs. Consequently, phosphorylation-deficient mutants of the repressors Yox1 and Yhp1 exhibit increased promoter occupancy and decreased expression of their target genes. Interestingly, although phosphorylation of the transcriptional activator Hcm1 on its N-terminus promotes its degradation, phosphorylation on its C-terminus is required for its activity, indicating that Cdk1 both activates and inhibits a single TF. We conclude that Cdk1 promotes gene expression by both activating transcriptional activators and inactivating transcriptional repressors. Furthermore, our data suggest that coordinated regulation of the TF network by Cdk1 is necessary for faithful cell division.

Degradation mechanism of over-charged LiCoO 2/mesocarbon microbeads battery during shallow depth of discharge cycling

DOE PAGES

Zhang, Lingling; Ma, Yulin; Cheng, Xinqun; ...

2016-08-26

LiCoO 2/mesocarbon microbeads (MCMB) batteries are over-charged to different voltage (4.4 V, 4.5 V, 4.6 V, and 4.7 V, respectively) for ten times, and then are cycled 1000 times for shallow depth of discharge. The morphology, structure, and electrochemical performance of the electrode materials were studied in detail in order to identify the capacity fading mechanism of over-charged battery after long-term cycling. The cycling performances of LiCoO 2/MCMB batteries are gradually aggravated with the increase of over-charging voltage and the degradation mechanism is diverse upon the degree of over-charging. Furthermore, the capacity fading after long-term cycling of battery over-charged tomore » 4.6 V or 4.7 V is mainly attributed to the cathodes. Soft X-ray absorption spectroscopy (XAS) demonstrates that the lower valence state of cobalt exists on the surface of the LiCoO 2 after serious over-charging (4.6 V or 4.7 V), and cobalt is dissolved then deposited on the anode according to the result of energy dispersive spectrometry (EDS). But, after shallow over-charging (4.4 V or 4.5 V), the capacity deterioration is proposed as the loss of active lithium, presented by the generation of the SEI film on the anode, which is verified by water washed tests.« less

The Down syndrome-related protein kinase DYRK1A phosphorylates p27Kip1 and Cyclin D1 and induces cell cycle exit and neuronal differentiation

PubMed Central

Soppa, Ulf; Schumacher, Julian; Florencio Ortiz, Victoria; Pasqualon, Tobias; Tejedor, Francisco J; Becker, Walter

2014-01-01

A fundamental question in neurobiology is how the balance between proliferation and differentiation of neuronal precursors is maintained to ensure that the proper number of brain neurons is generated. Substantial evidence implicates DYRK1A (dual specificity tyrosine-phosphorylation-regulated kinase 1A) as a candidate gene responsible for altered neuronal development and brain abnormalities in Down syndrome. Recent findings support the hypothesis that DYRK1A is involved in cell cycle control. Nonetheless, how DYRK1A contributes to neuronal cell cycle regulation and thereby affects neurogenesis remains poorly understood. In the present study we have investigated the mechanisms by which DYRK1A affects cell cycle regulation and neuronal differentiation in a human cell model, mouse neurons, and mouse brain. Dependent on its kinase activity and correlated with the dosage of overexpression, DYRK1A blocked proliferation of SH-SY5Y neuroblastoma cells within 24 h and arrested the cells in G1 phase. Sustained overexpression of DYRK1A induced G0 cell cycle exit and neuronal differentiation. Furthermore, we provide evidence that DYRK1A modulated protein stability of cell cycle-regulatory proteins. DYRK1A reduced cellular Cyclin D1 levels by phosphorylation on Thr286, which is known to induce proteasomal degradation. In addition, DYRK1A phosphorylated p27Kip1 on Ser10, resulting in protein stabilization. Inhibition of DYRK1A kinase activity reduced p27Kip1 Ser10 phosphorylation in cultured hippocampal neurons and in embryonic mouse brain. In aggregate, these results suggest a novel mechanism by which overexpression of DYRK1A may promote premature neuronal differentiation and contribute to altered brain development in Down syndrome. PMID:24806449

Argonaute-1 functions as a mitotic regulator by controlling Cyclin B during Drosophila early embryogenesis.

PubMed

Pushpavalli, Sreerangam N C V L; Sarkar, Arpita; Bag, Indira; Hunt, Clayton R; Ramaiah, M Janaki; Pandita, Tej K; Bhadra, Utpal; Pal-Bhadra, Manika

2014-02-01

The role of Ago-1 in microRNA (miRNA) biogenesis has been thoroughly studied, but little is known about its involvement in mitotic cell cycle progression. In this study, we established evidence of the regulatory role of Ago-1 in cell cycle control in association with the G2/M cyclin, cyclin B. Immunostaining of early embryos revealed that the maternal effect gene Ago-1 is essential for proper chromosome segregation, mitotic cell division, and spindle fiber assembly during early embryonic development. Ago-1 mutation resulted in the up-regulation of cyclin B-Cdk1 activity and down-regulation of p53, grp, mei-41, and wee1. The increased expression of cyclin B in Ago-1 mutants caused less stable microtubules and probably does not produce enough force to push the nuclei to the cortex, resulting in a decreased number of pole cells. The role of cyclin B in mitotic defects was further confirmed by suppressing the defects in the presence of one mutant copy of cyclin B. We identified involvement of 2 novel embryonic miRNAs--miR-981 and miR--317-for spatiotemporal regulation of cyclin B. In summary, our results demonstrate that the haploinsufficiency of maternal Ago-1 disrupts mitotic chromosome segregation and spindle fiber assembly via miRNA-guided control during early embryogenesis in Drosophila. The increased expression of cyclin B-Cdk1 and decreased activity of the Cdk1 inhibitor and cell cycle checkpoint proteins (mei-41 and grp) in Ago-1 mutant embryos allow the nuclei to enter into mitosis prematurely, even before completion of DNA replication. Thus, our results have established a novel role of Ago-1 as a regulator of the cell cycle.

Nicotine induces cell proliferation in association with cyclin D1 up-regulation and inhibits cell differentiation in association with p53 regulation in a murine pre-osteoblastic cell line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sato, Tsuyoshi; Abe, Takahiro; Nakamoto, Norimichi

Recent studies have suggested that nicotine critically affects bone metabolism. Many studies have examined the effects of nicotine on proliferation and differentiation, but the underlying molecular mechanisms remain unclear. We examined cell cycle regulators involved in the proliferation and differentiation of MC3T3-E1 cells. Nicotine induced cell proliferation in association with p53 down-regulation and cyclin D1 up-regulation. In differentiated cells, nicotine reduced alkaline phosphatase activity and mineralized nodule formation in dose-dependent manners. Furthermore, p53 expression was sustained in nicotine-treated cells during differentiation. These findings indicate that nicotine promotes the cell cycle and inhibits differentiation in association with p53 regulation in pre-osteoblasticmore » cells.« less

Impaired mitotic progression and preimplantation lethality in mice lacking OMCG1, a new evolutionarily conserved nuclear protein.

PubMed

Artus, Jérôme; Vandormael-Pournin, Sandrine; Frödin, Morten; Nacerddine, Karim; Babinet, Charles; Cohen-Tannoudji, Michel

2005-07-01

While highly conserved through evolution, the cell cycle has been extensively modified to adapt to new developmental programs. Recently, analyses of mouse mutants revealed that several important cell cycle regulators are either dispensable for development or have a tissue- or cell-type-specific function, indicating that many aspects of cell cycle regulation during mammalian embryo development remain to be elucidated. Here, we report on the characterization of a new gene, Omcg1, which codes for a nuclear zinc finger protein. Embryos lacking Omcg1 die by the end of preimplantation development. In vitro cultured Omcg1-null blastocysts exhibit a dramatic reduction in the total cell number, a high mitotic index, and the presence of abnormal mitotic figures. Importantly, we found that Omcg1 disruption results in the lengthening of M phase rather than in a mitotic block. We show that the mitotic delay in Omcg1-/- embryos is associated with neither a dysfunction of the spindle checkpoint nor abnormal global histone modifications. Taken together, these results suggest that Omcg1 is an important regulator of the cell cycle in the preimplantation embryo.

Impaired Mitotic Progression and Preimplantation Lethality in Mice Lacking OMCG1, a New Evolutionarily Conserved Nuclear Protein†

PubMed Central

Artus, Jérôme; Vandormael-Pournin, Sandrine; Frödin, Morten; Nacerddine, Karim; Babinet, Charles; Cohen-Tannoudji, Michel

2005-01-01

While highly conserved through evolution, the cell cycle has been extensively modified to adapt to new developmental programs. Recently, analyses of mouse mutants revealed that several important cell cycle regulators are either dispensable for development or have a tissue- or cell-type-specific function, indicating that many aspects of cell cycle regulation during mammalian embryo development remain to be elucidated. Here, we report on the characterization of a new gene, Omcg1, which codes for a nuclear zinc finger protein. Embryos lacking Omcg1 die by the end of preimplantation development. In vitro cultured Omcg1-null blastocysts exhibit a dramatic reduction in the total cell number, a high mitotic index, and the presence of abnormal mitotic figures. Importantly, we found that Omcg1 disruption results in the lengthening of M phase rather than in a mitotic block. We show that the mitotic delay in Omcg1−/− embryos is associated with neither a dysfunction of the spindle checkpoint nor abnormal global histone modifications. Taken together, these results suggest that Omcg1 is an important regulator of the cell cycle in the preimplantation embryo. PMID:15988037

Chemical Shuttle Additives in Lithium Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patterson, Mary

2013-03-31

The goals of this program were to discover and implement a redox shuttle that is compatible with large format lithium ion cells utilizing LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} (NMC) cathode material and to understand the mechanism of redox shuttle action. Many redox shuttles, both commercially available and experimental, were tested and much fundamental information regarding the mechanism of redox shuttle action was discovered. In particular, studies surrounding the mechanism of the reduction of the oxidized redox shuttle at the carbon anode surface were particularly revealing. The initial redox shuttle candidate, namely 2-(pentafluorophenyl)-tetrafluoro-1,3,2-benzodioxaborole (BDB) supplied by Argonne National Laboratory (ANL, Lemont,more » Illinois), did not effectively protect cells containing NMC cathodes from overcharge. The ANL-RS2 redox shuttle molecule, namely 1,4-bis(2-methoxyethoxy)-2,5-di-tert-butyl-benzene, which is a derivative of the commercially successful redox shuttle 2,5-di-tert-butyl-1,4-dimethoxybenzene (DDB, 3M, St. Paul, Minnesota), is an effective redox shuttle for cells employing LiFePO{sub 4} (LFP) cathode material. The main advantage of ANL-RS2 over DDB is its larger solubility in electrolyte; however, ANL-RS2 is not as stable as DDB. This shuttle also may be effectively used to rebalance cells in strings that utilize LFP cathodes. The shuttle is compatible with both LTO and graphite anode materials although the cell with graphite degrades faster than the cell with LTO, possibly because of a reaction with the SEI layer. The degradation products of redox shuttle ANL-RS2 were positively identified. Commercially available redox shuttles Li{sub 2}B{sub 12}F{sub 12} (Air Products, Allentown, Pennsylvania and Showa Denko, Japan) and DDB were evaluated and were found to be stable and effective redox shuttles at low C-rates. The Li{sub 2}B{sub 12}F{sub 12} is suitable for lithium ion cells utilizing a high voltage cathode (potential that is higher than NMC) and the DDB is useful for lithium ion cells with LFP cathodes (potential that is lower than NMC). A 4.5 V class redox shuttle provided by Argonne National Laboratory was evaluated which provides a few cycles of overcharge protection for lithium ion cells containing NMC cathodes but it is not stable enough for consideration. Thus, a redox shuttle with an appropriate redox potential and sufficient chemical and electrochemical stability for commercial use in larger format lithium ion cells with NMC cathodes was not found. Molecular imprinting of the redox shuttle molecule during solid electrolyte interphase (SEI) layer formation likely contributes to the successful reduction of oxidized redox shuttle species at carbon anodes. This helps to understand how a carbon anode covered with an SEI layer, that is supposed to be electrically insulating, can reduce the oxidized form of a redox shuttle.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Lingling; Ma, Yulin; Cheng, Xinqun

LiCoO 2/mesocarbon microbeads (MCMB) batteries are over-charged to different voltage (4.4 V, 4.5 V, 4.6 V, and 4.7 V, respectively) for ten times, and then are cycled 1000 times for shallow depth of discharge. The morphology, structure, and electrochemical performance of the electrode materials were studied in detail in order to identify the capacity fading mechanism of over-charged battery after long-term cycling. The cycling performances of LiCoO 2/MCMB batteries are gradually aggravated with the increase of over-charging voltage and the degradation mechanism is diverse upon the degree of over-charging. Furthermore, the capacity fading after long-term cycling of battery over-charged tomore » 4.6 V or 4.7 V is mainly attributed to the cathodes. Soft X-ray absorption spectroscopy (XAS) demonstrates that the lower valence state of cobalt exists on the surface of the LiCoO 2 after serious over-charging (4.6 V or 4.7 V), and cobalt is dissolved then deposited on the anode according to the result of energy dispersive spectrometry (EDS). But, after shallow over-charging (4.4 V or 4.5 V), the capacity deterioration is proposed as the loss of active lithium, presented by the generation of the SEI film on the anode, which is verified by water washed tests.« less

Cell Cycle-Dependent Expression of Dub3, Nanog and the p160 Family of Nuclear Receptor Coactivators (NCoAs) in Mouse Embryonic Stem Cells

PubMed Central

van der Laan, Siem; Golfetto, Eleonora; Vanacker, Jean-Marc; Maiorano, Domenico

2014-01-01

Pluripotency of embryonic stem cells (ESC) is tightly regulated by a network of transcription factors among which the estrogen-related receptor β (Esrrb). Esrrb contributes to the relaxation of the G1 to S-phase (G1/S) checkpoint in mouse ESCs by transcriptional control of the deubiquitylase Dub3 gene, contributing to Cdc25A persistence after DNA damage. We show that in mESCs, Dub3 gene expression is cell cycle regulated and is maximal prior G1/S transition. In addition, following UV-induced DNA damage in G1, Dub3 expression markedly increases in S-phase also suggesting a role in checkpoint recovery. Unexpectedly, we also observed cell cycle-regulation of Nanog expression, and not Oct4, reaching high levels prior to G1/S transition, finely mirroring Cyclin E1 fluctuations. Curiously, while Esrrb showed only limited cell-cycle oscillations, transcript levels of the p160 family of nuclear receptor coactivators (NCoAs) displayed strong cell cycle-dependent fluctuations. Since NCoAs function in concert with Esrrb in transcriptional activation, we focussed on NCoA1 whose levels specifically increase prior onset of Dub3 transcription. Using a reporter assay, we show that NCoA1 potentiates Esrrb-mediated transcription of Dub3 and we present evidence of protein interaction between the SRC1 splice variant NCoA1 and Esrrb. Finally, we show a differential developmental regulation of all members of the p160 family during neural conversion of mESCs. These findings suggest that in mouse ESCs, changes in the relative concentration of a coactivator at a given cell cycle phase, may contribute to modulation of the transcriptional activity of the core transcription factors of the pluripotent network and be implicated in cell fate decisions upon onset of differentiation. PMID:24695638

Cell cycle-dependent expression of Dub3, Nanog and the p160 family of nuclear receptor coactivators (NCoAs) in mouse embryonic stem cells.

PubMed

van der Laan, Siem; Golfetto, Eleonora; Vanacker, Jean-Marc; Maiorano, Domenico

2014-01-01

Pluripotency of embryonic stem cells (ESC) is tightly regulated by a network of transcription factors among which the estrogen-related receptor β (Esrrb). Esrrb contributes to the relaxation of the G1 to S-phase (G1/S) checkpoint in mouse ESCs by transcriptional control of the deubiquitylase Dub3 gene, contributing to Cdc25A persistence after DNA damage. We show that in mESCs, Dub3 gene expression is cell cycle regulated and is maximal prior G1/S transition. In addition, following UV-induced DNA damage in G1, Dub3 expression markedly increases in S-phase also suggesting a role in checkpoint recovery. Unexpectedly, we also observed cell cycle-regulation of Nanog expression, and not Oct4, reaching high levels prior to G1/S transition, finely mirroring Cyclin E1 fluctuations. Curiously, while Esrrb showed only limited cell-cycle oscillations, transcript levels of the p160 family of nuclear receptor coactivators (NCoAs) displayed strong cell cycle-dependent fluctuations. Since NCoAs function in concert with Esrrb in transcriptional activation, we focussed on NCoA1 whose levels specifically increase prior onset of Dub3 transcription. Using a reporter assay, we show that NCoA1 potentiates Esrrb-mediated transcription of Dub3 and we present evidence of protein interaction between the SRC1 splice variant NCoA1 and Esrrb. Finally, we show a differential developmental regulation of all members of the p160 family during neural conversion of mESCs. These findings suggest that in mouse ESCs, changes in the relative concentration of a coactivator at a given cell cycle phase, may contribute to modulation of the transcriptional activity of the core transcription factors of the pluripotent network and be implicated in cell fate decisions upon onset of differentiation.

Rapamycin ameliorates IgA nephropathy via cell cycle-dependent mechanisms

PubMed Central

Tian, Jihua; Wang, Yanhong; Liu, Xinyan; Zhou, Xiaoshuang

2014-01-01

IgA nephropathy is the most frequent type of glomerulonephritis worldwide. The role of cell cycle regulation in the pathogenesis of IgA nephropathy has been studied. The present study was designed to explore whether rapamycin ameliorates IgA nephropathy via cell cycle-dependent mechanisms. After establishing an IgA nephropathy model, rats were randomly divided into four groups. Coomassie Brilliant Blue was used to measure the 24-h urinary protein levels. Renal function was determined using an autoanalyzer. Proliferation was assayed via Proliferating Cell Nuclear Antigen (PCNA) immunohistochemistry. Rat mesangial cells were cultured and divided into the six groups. Methylthiazolyldiphenyl-tetrazolium bromide (MTT) and flow cytometry were used to detect cell proliferation and the cell cycle phase. Western blotting was performed to determine cyclin E, cyclin-dependent kinase 2, p27Kip1, p70S6K/p-p70S6K, and extracellular signal-regulated kinase 1/2/p- extracellular signal-regulated kinase 1/2 protein expression. A low dose of the mammalian target of rapamycin (mTOR) inhibitor rapamycin prevented an additional increase in proteinuria, protected kidney function, and reduced IgA deposition in a model of IgA nephropathy. Rapamycin inhibited mesangial cell proliferation and arrested the cell cycle in the G1 phase. Rapamycin did not affect the expression of cyclin E and cyclin-dependent kinase 2. However, rapamycin upregulated p27Kip1 at least in part via AKT (also known as protein kinase B)/mTOR. In conclusion, rapamycin can affect cell cycle regulation to inhibit mesangial cell proliferation, thereby reduce IgA deposition, and slow the progression of IgAN. PMID:25349217

Rapamycin ameliorates IgA nephropathy via cell cycle-dependent mechanisms.

PubMed

Tian, Jihua; Wang, Yanhong; Liu, Xinyan; Zhou, Xiaoshuang; Li, Rongshan

2015-07-01

IgA nephropathy is the most frequent type of glomerulonephritis worldwide. The role of cell cycle regulation in the pathogenesis of IgA nephropathy has been studied. The present study was designed to explore whether rapamycin ameliorates IgA nephropathy via cell cycle-dependent mechanisms. After establishing an IgA nephropathy model, rats were randomly divided into four groups. Coomassie Brilliant Blue was used to measure the 24-h urinary protein levels. Renal function was determined using an autoanalyzer. Proliferation was assayed via Proliferating Cell Nuclear Antigen (PCNA) immunohistochemistry. Rat mesangial cells were cultured and divided into the six groups. Methylthiazolyldiphenyl-tetrazolium bromide (MTT) and flow cytometry were used to detect cell proliferation and the cell cycle phase. Western blotting was performed to determine cyclin E, cyclin-dependent kinase 2, p27(Kip1), p70S6K/p-p70S6K, and extracellular signal-regulated kinase 1/2/p- extracellular signal-regulated kinase 1/2 protein expression. A low dose of the mammalian target of rapamycin (mTOR) inhibitor rapamycin prevented an additional increase in proteinuria, protected kidney function, and reduced IgA deposition in a model of IgA nephropathy. Rapamycin inhibited mesangial cell proliferation and arrested the cell cycle in the G1 phase. Rapamycin did not affect the expression of cyclin E and cyclin-dependent kinase 2. However, rapamycin upregulated p27(Kip1) at least in part via AKT (also known as protein kinase B)/mTOR. In conclusion, rapamycin can affect cell cycle regulation to inhibit mesangial cell proliferation, thereby reduce IgA deposition, and slow the progression of IgAN. © 2014 by the Society for Experimental Biology and Medicine.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Suna, E-mail: wangs3@mail.nih.gov; Zhou, Yifu; Andreyev, Oleg

Studying the proliferative ability of human bone marrow derived mesenchymal stem cells in hypoxic conditions can help us achieve the effective regeneration of ischemic injured myocardium. Cardiac-type fatty acid binding protein (FABP3) is a specific biomarker of muscle and heart tissue injury. This protein is purported to be involved in early myocardial development, adult myocardial tissue repair and responsible for the modulation of cell growth and proliferation. We have investigated the role of FABP3 in human bone marrow derived mesenchymal stem cells under ischemic conditions. MSCs from 12 donors were cultured either in standard normoxic or modified hypoxic conditions, andmore » the differential expression of FABP3 was tested by quantitative {sup RT}PCR and western blot. We also established stable FABP3 expression in MSCs and searched for variation in cellular proliferation and differentiation bioprocesses affected by hypoxic conditions. We identified: (1) the FABP3 differential expression pattern in the MSCs under hypoxic conditions; (2) over-expression of FABP3 inhibited the growth and proliferation of the MSCs; however, improved their survival in low oxygen environments; (3) the cell growth factors and positive cell cycle regulation genes, such as PCNA, APC, CCNB1, CCNB2 and CDC6 were all down-regulated; while the key negative cell cycle regulation genes TP53, BRCA1, CASP3 and CDKN1A were significantly up-regulated in the cells with FABP3 overexpression. Our data suggested that FABP3 was up-regulated under hypoxia; also negatively regulated the cell metabolic process and the mitotic cell cycle. Overexpression of FABP3 inhibited cell growth and proliferation via negative regulation of the cell cycle and down-regulation of cell growth factors, but enhances cell survival in hypoxic or ischemic conditions. - Highlights: • FABP3 expression pattern was studied in 12 human hypoxic-MSCs. • FABP3 mRNA and proteins are upregulated in the MSCs under hypoxic conditions. • Overexpression of FABP3 inhibits cell growth but advanced the MSC survival under hypoxia. • Overexpression of FABP3 down-regulate the cell cycle and stem cell signaling pathways.« less

Regulation of Akt/FoxO3a/Skp2 Axis Is Critically Involved in Berberine-Induced Cell Cycle Arrest in Hepatocellular Carcinoma Cells

PubMed Central

Li, Fanni; Dong, Xiwen; Lin, Peng; Jiang, Jianli

2018-01-01

The maintenance of ordinal cell cycle phases is a critical biological process in cancer genesis, which is a crucial target for anti-cancer drugs. As an important natural isoquinoline alkaloid from Chinese herbal medicine, Berberine (BBR) has been reported to possess anti-cancer potentiality to induce cell cycle arrest in hepatocellular carcinoma cells (HCC). However, the underlying mechanism remains to be elucidated. In our present study, G0/G1 phase cell cycle arrest was observed in berberine-treated Huh-7 and HepG2 cells. Mechanically, we observed that BBR could deactivate the Akt pathway, which consequently suppressed the S-phase kinase-associated protein 2 (Skp2) expression and enhanced the expression and translocation of Forkhead box O3a (FoxO3a) into nucleus. The translocated FoxO3a on one hand could directly promote the transcription of cyclin-dependent kinase inhibitors (CDKIs) p21Cip1 and p27Kip1, on the other hand, it could repress Skp2 expression, both of which lead to up-regulation of p21Cip1 and p27Kip1, causing G0/G1 phase cell cycle arrest in HCC. In conclusion, BBR promotes the expression of CDKIs p21Cip1 and p27Kip1 via regulating the Akt/FoxO3a/Skp2 axis and further induces HCC G0/G1 phase cell cycle arrest. This research uncovered a new mechanism of an anti-cancer effect of BBR. PMID:29360760

Proteomic analysis of the molecular response of Raji cells to maslinic acid treatment.

PubMed

Yap, W H; Khoo, K S; Lim, S H; Yeo, C C; Lim, Y M

2012-01-15

Maslinic acid, a natural pentacyclic triterpene has been shown to inhibit growth and induce apoptosis in some tumour cell lines. We studied the molecular response of Raji cells towards maslinic acid treatment. A proteomics approach was employed to identify the target proteins. Seventeen differentially expressed proteins including those involved in DNA replication, microtubule filament assembly, nucleo-cytoplasmic trafficking, cell signaling, energy metabolism and cytoskeletal organization were identified by MALDI TOF-TOF MS. The down-regulation of stathmin, Ran GTPase activating protein-1 (RanBP1), and microtubule associated protein RP/EB family member 1 (EB1) were confirmed by Western blotting. The study of the effect of maslinic acid on Raji cell cycle regulation showed that it induced a G1 cell cycle arrest. The differential proteomic changes in maslinic acid-treated Raji cells demonstrated that it also inhibited expression of dUTPase and stathmin which are known to induce early S and G2 cell cycle arrests. The mechanism of maslinic acid-induced cell cycle arrest may be mediated by inhibiting cyclin D1 expression and enhancing the levels of cell cycle-dependent kinase (CDK) inhibitor p21 protein. Maslinic acid suppressed nuclear factor-kappa B (NF-κB) activity which is known to stimulate expression of anti-apoptotic and cell cycle regulatory gene products. These results suggest that maslinic acid affects multiple signaling molecules and inhibits fundamental pathways regulating cell growth and survival in Raji cells. Copyright © 2011 Elsevier GmbH. All rights reserved.

Flipping the Switch from G1 to S Phase with E3 Ubiquitin Ligases

PubMed Central

Rizzardi, Lindsay F.

2012-01-01

The cell cycle ensures genome maintenance by coordinating the processes of DNA replication and chromosome segregation. Of particular importance is the irreversible transition from the G1 phase of the cell cycle to S phase. This transition marks the switch from preparing chromosomes for replication (“origin licensing”) to active DNA synthesis (“origin firing”). Ubiquitin-mediated proteolysis is essential for restricting DNA replication to only once per cell cycle and is the major mechanism regulating the G1 to S phase transition. Although some changes in protein levels are attributable to regulated mRNA abundance, protein degradation elicits very rapid changes in protein abundance and is critical for the sharp and irreversible transition from one cell cycle stage to the next. Not surprisingly, regulation of the G1-to-S phase transition is perturbed in most cancer cells, and deregulation of key molecular events in G1 and S phase drives not only cell proliferation but also genome instability. In this review we focus on the mechanisms by which E3 ubiquitin ligases control the irreversible transition from G1 to S phase in mammalian cells. PMID:23634252

p21 induction plays a dual role in anti-cancer activity of ursolic acid

PubMed Central

Zhang, Xudong; Song, Xinhua; Yin, Shutao; Zhao, Chong; Fan, Lihong

2015-01-01

Previous studies have shown that induction of G1 arrest and apoptosis by ursolic acid is associated with up-regulation of cyclin-dependent kinase inhibitor (CDKI) protein p21 in multiple types of cancer cells. However, the functional role of p21 induction in G1 cell cycle arrest and apoptosis, and the mechanisms of p21 induction by ursolic acid have not been critically addressed. In the current study, we demonstrated that p21 played a mediator role in G1 cell cycle arrest by ursolic acid, whereas p21-mediated up-regulation of Mcl-1 compromised apoptotic effect of ursolic acid. These results suggest that p21 induction plays a dual role in the anti-cancer activity of ursolic acid in terms of cell cycle and apoptosis regulation. p21 induction by ursolic acid was attributed to p53 transcriptional activation. Moreover, we found that ursolic acid was able to inhibit murine double minute-2 protein (MDM2) and T-LAK cell-originated protein kinase (TOPK), the two negative regulator of p53, which in turn contributed to ursolic acid-induced p53 activation. Our findings provided novel insights into understanding of the mechanisms involved in cell cycle arrest and apoptosis induction in response to ursolic acid exposure. PMID:26582056

Balance between fibroblast growth factor 10 and secreted frizzled-relate protein-1 controls the development of hair follicle by competitively regulating β-catenin signaling.

PubMed

Zhang, Haihua; Nan, Weixiao; Wang, Shiyong; Si, Huazhe; Li, Guangyu

2018-07-01

Growth of hairs depends on the regular development of hair follicles which are hypothesized to be regulated by fibroblast growth factor 10 (FGF10) and secreted frizzled-relate protein-1 (sFRP1). In the current study, the effect of FGF10 or sFRP1 on hair follicle cells was assessed and the possible mechanism mediating the interaction between FGF10 and sFRP1 in hair follicle cells was explored. Out root sheath (ORS) and dermal papilla (DP) cells were isolated from mink skin tissues and subjected to administrations of FGF10 (50 ng/ml) or sFRP1 (10 ng/ml). Then proliferation, cell cycle distribution, and migration potentials of both cell types were detected. Moreover, the nuclear translocation of β-catenin was determined. The results showed that the administration of FGF10 increased cell proliferation and migration potential in both cell types, which was associated with the up-regulated nuclear level of β-catenin. To the contrary, the administration of sFRP1 decreased cell proliferation and migration potentials while induced the G1 cell cycle arrest in both cell types by inhibiting nuclear translocation of β-catenin. Compared with the sole administrations, the co-treatment of FGF10 and sFRP1 had a medium effect on cell proliferation, cell cycle distribution, cell migration, and nuclear β-catenin level, representing an antagonistic interaction between the two factors, which was exerted by competitively regulating β-catenin pathway. Conclusively, the cycle of hair follicles was promoted by FGF10 while blocked by sFRP1 and the interplay between the two factors controlled the development of hair follicles by competitively regulating β-catenin signaling. Copyright © 2018. Published by Elsevier Masson SAS.

Decomposing self-estimates of intelligence: structure and sex differences across 12 nations.

PubMed

von Stumm, Sophie; Chamorro-Premuzic, Tomas; Furnham, Adrian

2009-05-01

This study examines the structure of self-estimates of intelligence (SEI) across 12 nations (Australia, Austria, Brazil, France, Iran, Israel, Malaysia, South Africa, Spain, Turkey, UK and US). Participants rated themselves on general and specific abilities from three popular models of intelligence: Gardner's multiple intelligences, Sternberg's triarchic theory of intelligence, and Goleman's emotional intelligence. The results showed that (a) laypeople across nations have similar and invariant concepts of intelligence, (b) concepts of intelligence are cross-culturally closely related to academic notions of intellectual ability and (c) sex differences in general and specific SEI favouring men are consistent across countries. Male hubris and female humility in SEI seem independent of sex differences in actual cognitive ability and national levels of masculinity-femininity. Furthermore, international mean differences in general SEI could not be attributed to discrepancies in national intelligence quotient (IQ) levels or to cultural variations.

MMSET is dynamically regulated during cell-cycle progression and promotes normal DNA replication.

PubMed

Evans, Debra L; Zhang, Haoxing; Ham, Hyoungjun; Pei, Huadong; Lee, SeungBaek; Kim, JungJin; Billadeau, Daniel D; Lou, Zhenkun

2016-01-01

The timely and precise duplication of cellular DNA is essential for maintaining genome integrity and is thus tightly-regulated. During mitosis and G1, the Origin Recognition Complex (ORC) binds to future replication origins, coordinating with multiple factors to load the minichromosome maintenance (MCM) complex onto future replication origins as part of the pre-replication complex (pre-RC). The pre-RC machinery, in turn, remains inactive until the subsequent S phase when it is required for replication fork formation, thereby initiating DNA replication. Multiple myeloma SET domain-containing protein (MMSET, a.k.a. WHSC1, NSD2) is a histone methyltransferase that is frequently overexpressed in aggressive cancers and is essential for normal human development. Several studies have suggested a role for MMSET in cell-cycle regulation; however, whether MMSET is itself regulated during cell-cycle progression has not been examined. In this study, we report that MMSET is degraded during S phase in a cullin-ring ligase 4-Cdt2 (CRL4(Cdt2)) and proteasome-dependent manner. Notably, we also report defects in DNA replication and a decreased association of pre-RC factors with chromatin in MMSET-depleted cells. Taken together, our results suggest a dynamic regulation of MMSET levels throughout the cell cycle, and further characterize the role of MMSET in DNA replication and cell-cycle progression.

DEC1 regulates breast cancer cell proliferation by stabilizing cyclin E protein and delays the progression of cell cycle S phase

PubMed Central

Bi, H; Li, S; Qu, X; Wang, M; Bai, X; Xu, Z; Ao, X; Jia, Z; Jiang, X; Yang, Y; Wu, H

2015-01-01

Breast cancer that is accompanied by a high level of cyclin E expression usually exhibits poor prognosis and clinical outcome. Several factors are known to regulate the level of cyclin E during the cell cycle progression. The transcription factor DEC1 (also known as STRA13 and SHARP2) plays an important role in cell proliferation and apoptosis. Nevertheless, the mechanism of its role in cell proliferation is poorly understood. In this study, using the breast cancer cell lines MCF-7 and T47D, we showed that DEC1 could inhibit the cell cycle progression of breast cancer cells independently of its transcriptional activity. The cell cycle-dependent timing of DEC1 overexpression could affect the progression of the cell cycle through regulating the level of cyclin E protein. DEC1 stabilized cyclin E at the protein level by interacting with cyclin E. Overexpression of DEC1 repressed the interaction between cyclin E and its E3 ligase Fbw7α, consequently reducing the level of polyunbiquitinated cyclin E and increased the accumulation of non-ubiquitinated cyclin E. Furthermore, DEC1 also promoted the nuclear accumulation of Cdk2 and the formation of cyclin E/Cdk2 complex, as well as upregulating the activity of the cyclin E/Cdk2 complex, which inhibited the subsequent association of cyclin A with Cdk2. This had the effect of prolonging the S phase and suppressing the growth of breast cancers in a mouse xenograft model. These events probably constitute the essential steps in DEC1-regulated cell proliferation, thus opening up the possibility of a protein-based molecular strategy for eliminating cancer cells that manifest a high-level expression of cyclin E. PMID:26402517

Controlling Solid-Electrolyte-Interphase Layer by Coating P-Type Semiconductor NiOx on Li4Ti5O12 for High-Energy-Density Lithium-Ion Batteries.

PubMed

Jo, Mi Ru; Lee, Gi-Hyeok; Kang, Yong-Mook

2015-12-23

Li4Ti5O12 is a promising anode material for rechargeable lithium batteries due to its well-known zero strain and superb kinetic properties. However, Li4Ti5O12 shows low energy density above 1 V vs Li(+)/Li. In order to improve the energy density of Li4Ti5O12, its low-voltage intercalation behavior beyond Li7Ti5O12 has been demonstrated. In this approach, the extended voltage window is accompanied by the decomposition of liquid electrolyte below 1 V, which would lead to an excessive formation of solid electrolyte interphase (SEI) films. We demonstrate an effective method to improve electrochemical performance of Li4Ti5O12 in a wide working voltage range by coating Li4Ti5O12 powder with p-type semiconductor NiOx. Ex situ XRD, XPS, and FTIR results show that the NiOx coating suppresses electrochemical reduction reactions of the organic SEI components to Li2CO3, thereby promoting reversibility of the charge/discharge process. The NiOx coating layer offers a stable SEI film for enhanced rate capability and cyclability.

Cell-cycle regulation of formin-mediated actin cable assembly

PubMed Central

Miao, Yansong; Wong, Catherine C. L.; Mennella, Vito; Michelot, Alphée; Agard, David A.; Holt, Liam J.; Yates, John R.; Drubin, David G.

2013-01-01

Assembly of appropriately oriented actin cables nucleated by formin proteins is necessary for many biological processes in diverse eukaryotes. However, compared with knowledge of how nucleation of dendritic actin filament arrays by the actin-related protein-2/3 complex is regulated, the in vivo regulatory mechanisms for actin cable formation are less clear. To gain insights into mechanisms for regulating actin cable assembly, we reconstituted the assembly process in vitro by introducing microspheres functionalized with the C terminus of the budding yeast formin Bni1 into extracts prepared from yeast cells at different cell-cycle stages. EM studies showed that unbranched actin filament bundles were reconstituted successfully in the yeast extracts. Only extracts enriched in the mitotic cyclin Clb2 were competent for actin cable assembly, and cyclin-dependent kinase 1 activity was indispensible. Cyclin-dependent kinase 1 activity also was found to regulate cable assembly in vivo. Here we present evidence that formin cell-cycle regulation is conserved in vertebrates. The use of the cable-reconstitution system to test roles for the key actin-binding proteins tropomyosin, capping protein, and cofilin provided important insights into assembly regulation. Furthermore, using mass spectrometry, we identified components of the actin cables formed in yeast extracts, providing the basis for comprehensive understanding of cable assembly and regulation. PMID:24133141

Two Geminin homologs regulate DNA replication in silkworm, Bombyx mori

PubMed Central

Tang, Xiao-Fang; Chen, Xiang-Yun; Zhang, Chun-Dong; Li, Yao-Feng; Liu, Tai-Hang; Zhou, Xiao-Lin; Wang, La; Zhang, Qian; Chen, Peng; Lu, Cheng; Pan, Min-Hui

2017-01-01

ABSTRACT DNA replication is rigorously controlled in cells to ensure that the genome duplicates exactly once per cell cycle. Geminin is a small nucleoprotein, which prevents DNA rereplication by directly binding to and inhibiting the DNA replication licensing factor, Cdt1. In this study, we have identified 2 Geminin genes, BmGeminin1 and BmGeminn2, in silkworm, Bombyx mori. These genes contain the Geminin conserved coiled-coil domain and are periodically localized in the nucleus during the S-G2 phase but are degraded at anaphase in mitosis. Both BmGeminin1 and BmGeminin2 are able to homodimerize and interact with BmCdt1 in cells. In addition, BmGeminin1 and BmGeminin2 can interact with each other. Overexpression of BmGeminin1 affects cell cycle progression: cell cycle is arrested in S phase, and RNA interference of BmGeminin1 leads to rereplication. In contrast, overexpression or knockdown of BmGeminin2 with RNAi did not significantly affect cell cycle, while more rereplication occurred when BmGeminin1 and BmGeminin2 together were knocked down in cells than when only BmGeminin1 was knocked down. These data suggest that both BmGeminin1 and BmGeminin2 are involved in the regulation of DNA replication. These findings provide insight into the function of Geminin and contribute to our understanding of the regulation mechanism of cell cycle in silkworm. PMID:28379781

Lithium loss in the solid electrolyte interphase: Lithium quantification of aged lithium ion battery graphite electrodes by means of laser ablation inductively coupled plasma mass spectrometry and inductively coupled plasma optical emission spectroscopy

NASA Astrophysics Data System (ADS)

Schwieters, Timo; Evertz, Marco; Mense, Maximilian; Winter, Martin; Nowak, Sascha

2017-07-01

In this work we present a new method using LA-ICP-MS to quantitatively determine the lithium content in aged graphite electrodes of a lithium ion battery (LIB) by performing total depth profiling. Matrix matched solid external standards are prepared using a solid doping approach to avoid elemental fractionation effects during the measurement. The results are compared and matched to the established ICP-OES technique for bulk quantification after performing a microwave assisted acid digestion. The method is applied to aged graphite electrodes in order to determine the lithium immobilization (= "Li loss") in the solid electrolyte interphase after the first cycle of formation. For this, different samples including a reference sample are created to obtain varying thicknesses of the SEI covering the electrode particles. By applying defined charging voltages, an initial lithiation process is performed to obtain specific graphite intercalation compounds (GICs, with target stoichiometries of LiC30, LiC18, LiC12 and LiC6). Afterwards, the graphite electrode is completely discharged to obtain samples without mobile, thus active lithium in its lattice. Taking the amount of lithium into account which originates from the residues of the LiPF6 (dissolved in the carbon components containing electrolyte), it is possible to subtract the amount of lithium in the SEI.

Morphogenesis checkpoint kinase Swe1 is the executor of lipolysis-dependent cell-cycle progression.

PubMed

Chauhan, Neha; Visram, Myriam; Cristobal-Sarramian, Alvaro; Sarkleti, Florian; Kohlwein, Sepp D

2015-03-10

Cell growth and division requires the precise duplication of cellular DNA content but also of membranes and organelles. Knowledge about the cell-cycle-dependent regulation of membrane and storage lipid homeostasis is only rudimentary. Previous work from our laboratory has shown that the breakdown of triacylglycerols (TGs) is regulated in a cell-cycle-dependent manner, by activation of the Tgl4 lipase by the major cyclin-dependent kinase Cdc28. The lipases Tgl3 and Tgl4 are required for efficient cell-cycle progression during the G1/S (Gap1/replication phase) transition, at the onset of bud formation, and their absence leads to a cell-cycle delay. We now show that defective lipolysis activates the Swe1 morphogenesis checkpoint kinase that halts cell-cycle progression by phosphorylation of Cdc28 at tyrosine residue 19. Saturated long-chain fatty acids and phytosphingosine supplementation rescue the cell-cycle delay in the Tgl3/Tgl4 lipase-deficient strain, suggesting that Swe1 activity responds to imbalanced sphingolipid metabolism, in the absence of TG degradation. We propose a model by which TG-derived sphingolipids are required to activate the protein phosphatase 2A (PP2A(Cdc55)) to attenuate Swe1 phosphorylation and its inhibitory effect on Cdc28 at the G1/S transition of the cell cycle.

Estrogen receptor alpha is cell cycle-regulated and regulates the cell cycle in a ligand-dependent fashion

PubMed Central

JavanMoghadam, Sonia; Weihua, Zhang; Hunt, Kelly K.; Keyomarsi, Khandan

2016-01-01

ABSTRACT Estrogen receptor alpha (ERα) has been implicated in several cell cycle regulatory events and is an important predictive marker of disease outcome in breast cancer patients. Here, we aimed to elucidate the mechanism through which ERα influences proliferation in breast cancer cells. Our results show that ERα protein is cell cycle-regulated in human breast cancer cells and that the presence of 17-β-estradiol (E2) in the culture medium shortened the cell cycle significantly (by 4.5 hours, P < 0.05) compared with unliganded conditions. The alterations in cell cycle duration were observed in the S and G2/M phases, whereas the G1 phase was indistinguishable under liganded and unliganded conditions. In addition, ERα knockdown in MCF-7 cells accelerated mitotic exit, whereas transfection of ERα-negative MDA-MB-231 cells with exogenous ERα significantly shortened the S and G2/M phases (by 9.1 hours, P < 0.05) compared with parental cells. Finally, treatment of MCF-7 cells with antiestrogens revealed that tamoxifen yields a slower cell cycle progression through the S and G2/M phases than fulvestrant does, presumably because of the destabilizing effect of fulvestrant on ERα protein. Together, these results show that ERα modulates breast cancer cell proliferation by regulating events during the S and G2/M phases of the cell cycle in a ligand-dependent fashion. These results provide the rationale for an effective treatment strategy that includes a cell cycle inhibitor in combination with a drug that lowers estrogen levels, such as an aromatase inhibitor, and an antiestrogen that does not result in the degradation of ERα, such as tamoxifen. PMID:27049344

Estrogen receptor alpha is cell cycle-regulated and regulates the cell cycle in a ligand-dependent fashion.

PubMed

JavanMoghadam, Sonia; Weihua, Zhang; Hunt, Kelly K; Keyomarsi, Khandan

2016-06-17

Estrogen receptor alpha (ERα) has been implicated in several cell cycle regulatory events and is an important predictive marker of disease outcome in breast cancer patients. Here, we aimed to elucidate the mechanism through which ERα influences proliferation in breast cancer cells. Our results show that ERα protein is cell cycle-regulated in human breast cancer cells and that the presence of 17-β-estradiol (E2) in the culture medium shortened the cell cycle significantly (by 4.5 hours, P < 0.05) compared with unliganded conditions. The alterations in cell cycle duration were observed in the S and G2/M phases, whereas the G1 phase was indistinguishable under liganded and unliganded conditions. In addition, ERα knockdown in MCF-7 cells accelerated mitotic exit, whereas transfection of ERα-negative MDA-MB-231 cells with exogenous ERα significantly shortened the S and G2/M phases (by 9.1 hours, P < 0.05) compared with parental cells. Finally, treatment of MCF-7 cells with antiestrogens revealed that tamoxifen yields a slower cell cycle progression through the S and G2/M phases than fulvestrant does, presumably because of the destabilizing effect of fulvestrant on ERα protein. Together, these results show that ERα modulates breast cancer cell proliferation by regulating events during the S and G2/M phases of the cell cycle in a ligand-dependent fashion. These results provide the rationale for an effective treatment strategy that includes a cell cycle inhibitor in combination with a drug that lowers estrogen levels, such as an aromatase inhibitor, and an antiestrogen that does not result in the degradation of ERα, such as tamoxifen.

Cypermethrin Induces Macrophages Death through Cell Cycle Arrest and Oxidative Stress-Mediated JNK/ERK Signaling Regulated Apoptosis

PubMed Central

Huang, Fang; Liu, Qiaoyun; Xie, Shujun; Xu, Jian; Huang, Bo; Wu, Yihua; Xia, Dajing

2016-01-01

Cypermethrin is one of the most highly effective synthetic pyrethroid insecticides. The toxicity of cypermethrin to the reproductive and nervous systems has been well studied. However, little is known about the toxic effect of cypermethrin on immune cells such as macrophages. Here, we investigated the cytotoxicity of cypermethrin on macrophages and the underlying molecular mechanisms. We found that cypermethrin reduced cell viability and induced apoptosis in RAW 264.7 cells. Cypermethrin also increased reactive oxygen species (ROS) production and DNA damage in a dose-dependent manner. Moreover, cypermethrin-induced G1 cell cycle arrest was associated with an enhanced expression of p21, wild-type p53, and down-regulation of cyclin D1, cyclin E and CDK4. In addition, cypermethrin treatment activated MAPK signal pathways by inducing c-Jun N-terminal kinase (JNK) and extracellular regulated protein kinases 1/2 ERK1/2 phosphorylation, and increased the cleaved poly ADP-ribose polymerase (PARP). Further, pretreatment with antioxidant N-acetylcysteine (NAC) effectively abrogated cypermethrin-induced cell cytotoxicity, G1 cell cycle arrest, DNA damage, PARP activity, and JNK and ERK1/2 activation. The specific JNK inhibitor (SP600125) and ERK1/2 inhibitor (PD98059) effectively reversed the phosphorylation level of JNK and ERK1/2, and attenuated the apoptosis. Taken together, these data suggested that cypermethrin caused immune cell death via inducing cell cycle arrest and apoptosis regulated by ROS-mediated JNK/ERK pathway. PMID:27322250

APC/C and retinoblastoma interaction: cross-talk of retinoblastoma protein with the ubiquitin proteasome pathway.

PubMed

Ramanujan, Ajeena; Tiwari, Swati

2016-10-01

The ubiquitin (Ub) ligase anaphase promoting complex/cyclosome (APC/C) and the tumour suppressor retinoblastoma protein (pRB) play key roles in cell cycle regulation. APC/C is a critical regulator of mitosis and G1-phase of the cell cycle whereas pRB keeps a check on proliferation by inhibiting transition to the S-phase. APC/C and pRB interact with each other via the co-activator of APC/C, FZR1, providing an alternative pathway of regulation of G1 to S transition by pRB using a post-translational mechanism. Both pRB and FZR1 have complex roles and are implicated not only in regulation of cell proliferation but also in differentiation, quiescence, apoptosis, maintenance of chromosomal integrity and metabolism. Both are also targeted by transforming viruses. We discuss recent advances in our understanding of the involvement of APC/C and pRB in cell cycle based decisions and how these insights will be useful for development of anti-cancer and anti-viral drugs. © 2016 The Author(s).

APC/C and retinoblastoma interaction: cross-talk of retinoblastoma protein with the ubiquitin proteasome pathway

PubMed Central

Ramanujan, Ajeena; Tiwari, Swati

2016-01-01

The ubiquitin (Ub) ligase anaphase promoting complex/cyclosome (APC/C) and the tumour suppressor retinoblastoma protein (pRB) play key roles in cell cycle regulation. APC/C is a critical regulator of mitosis and G1-phase of the cell cycle whereas pRB keeps a check on proliferation by inhibiting transition to the S-phase. APC/C and pRB interact with each other via the co-activator of APC/C, FZR1, providing an alternative pathway of regulation of G1 to S transition by pRB using a post-translational mechanism. Both pRB and FZR1 have complex roles and are implicated not only in regulation of cell proliferation but also in differentiation, quiescence, apoptosis, maintenance of chromosomal integrity and metabolism. Both are also targeted by transforming viruses. We discuss recent advances in our understanding of the involvement of APC/C and pRB in cell cycle based decisions and how these insights will be useful for development of anti-cancer and anti-viral drugs. PMID:27402801

InSight/SEIS@Mars Educational program : Sharing the InSight NASA mission and the Seismic Discovery of Mars with a International Network of classes

NASA Astrophysics Data System (ADS)

Lognonne, P. H.; Berenguer, J. L.; Sauron, A.; Denton, P.; Carrer, D.; Taber, J.; Bravo, T. K.; Gaboriaud, A.; Houston Jones, J.; Banerdt, W. B.; Martinuzzi, J. M.

2015-12-01

The InSIght mission will deploy in September 2016 a Geophysical Station on Mars, equipped with a suite of geophysical instruments, including 3 axis Very Broad Band Seismometer, 3 axis Short Period Seismometer, 3 axis Flux gate Magnetometer, Heat flow probe, geodetic beacon, infrasound/microbarometer, wind sensors and cameras. As for all NASA missions, Children and teenagers will be associated to the mission in the framework of the K12 InSight program, part of it being associated to the SEIS instrument.The two faces of the InSight/SEIS Education program are directed toward the promotion of Space Technologies and of Space Science.For Space technologies, this has already started with the InSight Elysium Educational project. The goal of the project, supported by CNES and performed by Technical High School near Toulouse, was the fabrication of a full scale mockup of the lander (see more at https://jeunes.cnes.fr/fr/elysium-le-jumeau-terrestre-dinsight ). The mockup was exhibited during the June, 2015 Paris air show. More than 300 students participated to the Elysium project.For Space Science, this will be made with the SEIS@Mars Educational project. Its plan is to transmit the SEIS data to a network of several hundred of middle and high schools worldwide, associated to existing "seismo(graph) at school" programs in the United States (https://www.iris.edu/hq/sis), France (www.edusismo.org) Switzerland (www.seismoatschool.ethz.ch) and United Kingdom (http://www.bgs.ac.uk/schoolseismology/). If the transmission of these data to the SEIS@school network will be automatic after their release by the NASA Planetary Data System, an earlier transmission will be made, especially after mid 2017, but also before through the integration of selected Schools to the project activities: the selected classrooms will perform the same activities as the project scientists. They will have to process rapidly the proprietary data in order to identify MarsQuake(s) and will be allowed to perform Event requests to the lander in order to get the associated high frequencies of these events. These school will therefore be fully associated to the InSight/SEIS discoveries. The SEIS@Mars project will therefore allow the students to perform scientific analysis almost at the same time as the International "professional" seismologists.

Functional synergy between DP-1 and E2F-1 in the cell cycle-regulating transcription factor DRTF1/E2F.

PubMed Central

Bandara, L R; Buck, V M; Zamanian, M; Johnston, L H; La Thangue, N B

1993-01-01

It is widely believed that the cellular transcription factor DRTF1/E2F integrates cell cycle events with the transcription apparatus because during cell cycle progression in mammalian cells it interacts with molecules that are important regulators of cellular proliferation, such as the retinoblastoma tumour suppressor gene product (pRb), p107, cyclins and cyclin-dependent kinases. Thus, pRb, which negatively regulates early cell cycle progression and is frequently mutated in tumour cells, and the Rb-related protein p107, bind to and repress the transcriptional activity of DRTF1/E2F. Viral oncoproteins, such as adenovirus E1a and SV40 large T antigen, overcome such repression by sequestering pRb and p107 and in so doing are likely to activate genes regulated by DRTF1/E2F, such as cdc2, c-myc and DHFR. Two sequence-specific DNA binding proteins, E2F-1 and DP-1, which bind to the E2F site, contain a small region of similarity. The functional relationship between them has, however, been unclear. We report here that DP-1 and E2F-1 exist in a DNA binding complex in vivo and that they bind efficiently and preferentially as a heterodimer to the E2F site. Moreover, studies in yeast and Drosophila cells indicate that DP-1 and E2F-1 interact synergistically in E2F site-dependent transcriptional activation. Images PMID:8223441

Precise Perforation and Scalable Production of Si Particles from Low-Grade Sources for High-Performance Lithium Ion Battery Anodes.

PubMed

Zong, Linqi; Jin, Yan; Liu, Chang; Zhu, Bin; Hu, Xiaozhen; Lu, Zhenda; Zhu, Jia

2016-11-09

Alloy anodes, particularly silicon, have been intensively pursued as one of the most promising anode materials for the next generation lithium-ion battery primarily because of high specific capacity (>4000 mAh/g) and elemental abundance. In the past decade, various nanostructures with porosity or void space designs have been demonstrated to be effective to accommodate large volume expansion (∼300%) and to provide stable solid electrolyte interphase (SEI) during electrochemical cycling. However, how to produce these building blocks with precise morphology control at large scale and low cost remains a challenge. In addition, most of nanostructured silicon suffers from poor Coulombic efficiency due to a large surface area and Li ion trapping at the surface coating. Here we demonstrate a unique nanoperforation process, combining modified ball milling, annealing, and acid treating, to produce porous Si with precise and continuous porosity control (from 17% to 70%), directly from low cost metallurgical silicon source (99% purity, ∼ $1/kg). The produced porous Si coated with graphene by simple ball milling can deliver a reversible specific capacity of 1250 mAh/g over 1000 cycles at the rate of 1C, with Coulombic efficiency of first cycle over 89.5%. The porous networks also provide efficient ion and electron pathways and therefore enable excellent rate performance of 880 mAh/g at the rate of 5C. Being able to produce particles with precise porosity control through scalable processes from low-grade materials, it is expected that this nanoperforation may play a role in the next generation lithium ion battery anodes, as well as many other potential applications such as optoelectronics and thermoelectrics.

Facile Stabilization of the Sodium Metal Anode with Additives: Unexpected Key Role of Sodium Polysulfide and Adverse Effect of Sodium Nitrate.

PubMed

Wang, Huan; Wang, Chuanlong; Matios, Edward; Li, Weiyang

2018-06-25

Sodium metal is an attractive anode for next-generation energy storage systems owing to its high specific capacity, low cost, and high abundance. Nevertheless, uncontrolled Na dendrite growth caused by the formation of unstable solid electrolyte interphase (SEI) leads to poor cycling performance and severe safety concerns. Sodium polysulfide (Na 2 S 6 ) alone is revealed to serve as a positive additive or pre-passivation agent in ether electrolyte to improve the long-term stability and reversibility of the Na anode, while Na 2 S 6 -NaNO 3 as co-additive has an adverse effect, contrary to the prior findings in the lithium anode system. A superior cycling behavior of Na anode is first demonstrated at a current density up to 10 mA cm -2 and a capacity up to 5 mAh cm -2 over 100 cycles. As a proof of concept, a high-capacity Na-S battery was prepared by pre-passivating the Na anode with Na 2 S 6 . This study gives insights into understanding the differences between Li and Na systems. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tin anode for sodium-ion batteries using natural wood fiber as a mechanical buffer and electrolyte reservoir.

PubMed

Zhu, Hongli; Jia, Zheng; Chen, Yuchen; Weadock, Nicholas; Wan, Jiayu; Vaaland, Oeyvind; Han, Xiaogang; Li, Teng; Hu, Liangbing

2013-07-10

Sodium (Na)-ion batteries offer an attractive option for low cost grid scale storage due to the abundance of Na. Tin (Sn) is touted as a high capacity anode for Na-ion batteries with a high theoretical capacity of 847 mAh/g, but it has several limitations such as large volume expansion with cycling, slow kinetics, and unstable solid electrolyte interphase (SEI) formation. In this article, we demonstrate that an anode consisting of a Sn thin film deposited on a hierarchical wood fiber substrate simultaneously addresses all the challenges associated with Sn anodes. The soft nature of wood fibers effectively releases the mechanical stresses associated with the sodiation process, and the mesoporous structure functions as an electrolyte reservoir that allows for ion transport through the outer and inner surface of the fiber. These properties are confirmed experimentally and computationally. A stable cycling performance of 400 cycles with an initial capacity of 339 mAh/g is demonstrated; a significant improvement over other reported Sn nanostructures. The soft and mesoporous wood fiber substrate can be utilized as a new platform for low cost Na-ion batteries.

Multiple functions of p21 in cell cycle, apoptosis and transcriptional regulation after DNA damage.

PubMed

Karimian, Ansar; Ahmadi, Yasin; Yousefi, Bahman

2016-06-01

An appropriate control over cell cycle progression depends on many factors. Cyclin-dependent kinase (CDK) inhibitor p21 (also known as p21(WAF1/Cip1)) is one of these factors that promote cell cycle arrest in response to a variety of stimuli. The inhibitory effect of P21 on cell cycle progression correlates with its nuclear localization. P21 can be induced by both p53-dependent and p53-independent mechanisms. Some other important functions attributed to p21 include transcriptional regulation, modulation or inhibition of apoptosis. These functions are largely dependent on direct p21/protein interactions and also on p21 subcellular localizations. In addition, p21 can play a role in DNA repair by interacting with proliferating cell nuclear antigen (PCNA). In this review, we will focus on the multiple functions of p21 in cell cycle regulation, apoptosis and gene transcription after DNA damage and briefly discuss the pathways and factors that have critical roles in p21 expression and activity. Copyright © 2016 Elsevier B.V. All rights reserved.

A novel function for Foxm1 in interkinetic nuclear migration in the developing telencephalon and anxiety-related behavior.

PubMed

Wu, Xiaojing; Gu, Xiaochun; Han, Xiaoning; Du, Ailing; Jiang, Yan; Zhang, Xiaoyun; Wang, Yanjie; Cao, Guangliang; Zhao, Chunjie

2014-01-22

Interkinetic nuclear migration (INM) is a key feature of cortical neurogenesis. INM functions to maximize the output of the neuroepithelium, and more importantly, balance the self-renewal and differentiation of the progenitors. Although INM has been reported to be highly correlated with the cell cycle, little is known about the effects of cell cycle regulators on INM. In this study, by crossing Foxm1(fl/fl) mice with Emx1-Cre line, we report that a conditional disruption of forkhead transcription factor M1 (Foxm1) in dorsal telencephalon results in abnormal cell cycle progression, leading to impaired INM through the downregulation of Cyclin b1 and Cdc25b. The impairment of INM disturbs the synchronization of apical progenitors (APs) and promotes the transition from APs to basal progenitors (BPs) in a cell-autonomous fashion. Moreover, ablation of Foxm1 causes anxiety-related behaviors in adulthood. Thus, this study provides evidence of linkages among the cell cycle regulator Foxm1, INM, and adult behavior.

Identification of She3 as an SCFGrr1 Substrate in Budding Yeast

PubMed Central

Wang, Ruiwen; Solomon, Mark J.

2012-01-01

The highly orchestrated progression of the cell cycle depends on the degradation of many regulatory proteins at different cell cycle stages. One of the key cell cycle ubiquitin ligases is the Skp1-cullin-F-box (SCF) complex. Acting in concert with the substrate-binding F-box protein Grr1, SCFGrr1 promotes the degradation of cell cycle regulators as well as various metabolic enzymes. Using a yeast two-hybrid assay with a Grr1 derivative as the bait, we identified She3, which is an adaptor protein in the asymmetric mRNA transport system, as a novel Grr1 substrate. We generated stabilized She3 mutants, which no longer bound to Grr1, and found that the degradation of She3 is not required for regulating asymmetric mRNA transport. However, She3 stabilization leads to slower growth compared to wild-type cells in a co-culture assay, demonstrating that the degradation of She3 by Grr1 is required for optimal cell growth. PMID:23144720

An R132H Mutation in Isocitrate Dehydrogenase 1 Enhances p21 Expression and Inhibits Phosphorylation of Retinoblastoma Protein in Glioma Cells

PubMed Central

Miyata, Satsuki; Urabe, Masashi; Gomi, Akira; Nagai, Mutsumi; Yamaguchi, Takashi; Tsukahara, Tomonori; Mizukami, Hiroaki; Kume, Akihiro; Ozawa, Keiya; Watanabe, Eiju

2013-01-01

Cytosolic isocitrate dehydrogenase 1 (IDH1) with an R132H mutation in brain tumors loses its enzymatic activity for catalyzing isocitrate to α-ketoglutarate (α-KG) and acquires new activity whereby it converts α-KG to 2-hydroxyglutarate. The IDH1 mutation induces down-regulation of tricarboxylic acid cycle intermediates and up-regulation of lipid metabolism. Sterol regulatory element-binding proteins (SREBPs) regulate not only the synthesis of cholesterol and fatty acids but also acyclin-dependent kinase inhibitor p21 that halts the cell cycle at G1. Here we show that SREBPs were up-regulated in U87 human glioblastoma cells transfected with an IDH1R132H-expression plasmid. Small interfering ribonucleic acid (siRNA) for SREBP1 specifically decreased p21 messenger RNA (mRNA) levels independent of the p53 pathway. In IDH1R132H-expressing U87 cells, phosphorylation of Retinoblastoma (Rb) protein also decreased. We propose that metabolic changes induced by the IDH1 mutation enhance p21 expression via SREBP1 and inhibit phosphorylation of Rb, which slows progressionof the cell cycle and may be associated with non-aggressive features of gliomas with an IDH1 mutation. PMID:24077277

An R132H mutation in isocitrate dehydrogenase 1 enhances p21 expression and inhibits phosphorylation of retinoblastoma protein in glioma cells.

PubMed

Miyata, Satsuki; Urabe, Masashi; Gomi, Akira; Nagai, Mutsumi; Yamaguchi, Takashi; Tsukahara, Tomonori; Mizukami, Hiroaki; Kume, Akihiro; Ozawa, Keiya; Watanabe, Eiju

2013-01-01

Cytosolic isocitrate dehydrogenase 1 (IDH1) with an R132H mutation in brain tumors loses its enzymatic activity for catalyzing isocitrate to α-ketoglutarate (α-KG) and acquires new activity whereby it converts α-KG to 2-hydroxyglutarate. The IDH1 mutation induces down-regulation of tricarboxylic acid cycle intermediates and up-regulation of lipid metabolism. Sterol regulatory element-binding proteins (SREBPs) regulate not only the synthesis of cholesterol and fatty acids but also acyclin-dependent kinase inhibitor p21 that halts the cell cycle at G1. Here we show that SREBPs were up-regulated in U87 human glioblastoma cells transfected with an IDH1(R132H)-expression plasmid. Small interfering ribonucleic acid (siRNA) for SREBP1 specifically decreased p21 messenger RNA (mRNA) levels independent of the p53 pathway. In IDH1(R132H)-expressing U87 cells, phosphorylation of Retinoblastoma (Rb) protein also decreased. We propose that metabolic changes induced by the IDH1 mutation enhance p21 expression via SREBP1 and inhibit phosphorylation of Rb, which slows progression of the cell cycle and may be associated with non-aggressive features of gliomas with an IDH1 mutation.

Levels of Ycg1 Limit Condensin Function during the Cell Cycle

PubMed Central

Arsenault, Heather E.; Benanti, Jennifer A.

2016-01-01

During mitosis chromosomes are condensed to facilitate their segregation, through a process mediated by the condensin complex. Although several factors that promote maximal condensin activity during mitosis have been identified, the mechanisms that downregulate condensin activity during interphase are largely unknown. Here, we demonstrate that Ycg1, the Cap-G subunit of budding yeast condensin, is cell cycle-regulated with levels peaking in mitosis and decreasing as cells enter G1 phase. This cyclical expression pattern is established by a combination of cell cycle-regulated transcription and constitutive degradation. Interestingly, overexpression of YCG1 and mutations that stabilize Ycg1 each result in delayed cell-cycle entry and an overall proliferation defect. Overexpression of no other condensin subunit impacts the cell cycle, suggesting that Ycg1 is limiting for condensin complex formation. Consistent with this possibility, we find that levels of intact condensin complex are reduced in G1 phase compared to mitosis, and that increased Ycg1 expression leads to increases in both levels of condensin complex and binding to chromatin in G1. Together, these results demonstrate that Ycg1 levels limit condensin function in interphase cells, and suggest that the association of condensin with chromosomes must be reduced following mitosis to enable efficient progression through the cell cycle. PMID:27463097

Jasmonate Controls Leaf Growth by Repressing Cell Proliferation and the Onset of Endoreduplication while Maintaining a Potential Stand-By Mode1[W][OA

PubMed Central

Noir, Sandra; Bömer, Moritz; Takahashi, Naoki; Ishida, Takashi; Tsui, Tjir-Li; Balbi, Virginia; Shanahan, Hugh; Sugimoto, Keiko; Devoto, Alessandra

2013-01-01

Phytohormones regulate plant growth from cell division to organ development. Jasmonates (JAs) are signaling molecules that have been implicated in stress-induced responses. However, they have also been shown to inhibit plant growth, but the mechanisms are not well understood. The effects of methyl jasmonate (MeJA) on leaf growth regulation were investigated in Arabidopsis (Arabidopsis thaliana) mutants altered in JA synthesis and perception, allene oxide synthase and coi1-16B (for coronatine insensitive1), respectively. We show that MeJA inhibits leaf growth through the JA receptor COI1 by reducing both cell number and size. Further investigations using flow cytometry analyses allowed us to evaluate ploidy levels and to monitor cell cycle progression in leaves and cotyledons of Arabidopsis and/or Nicotiana benthamiana at different stages of development. Additionally, a novel global transcription profiling analysis involving continuous treatment with MeJA was carried out to identify the molecular players whose expression is regulated during leaf development by this hormone and COI1. The results of these studies revealed that MeJA delays the switch from the mitotic cell cycle to the endoreduplication cycle, which accompanies cell expansion, in a COI1-dependent manner and inhibits the mitotic cycle itself, arresting cells in G1 phase prior to the S-phase transition. Significantly, we show that MeJA activates critical regulators of endoreduplication and affects the expression of key determinants of DNA replication. Our discoveries also suggest that MeJA may contribute to the maintenance of a cellular “stand-by mode” by keeping the expression of ribosomal genes at an elevated level. Finally, we propose a novel model for MeJA-regulated COI1-dependent leaf growth inhibition. PMID:23439917

Case Study: IRS Business System Modernization Process Improvement

DTIC Science & Technology

2004-03-01

31 CMU/SEI-2004-TR-002 iii List of Figures Figure 1: Managing Organizational Change ............................................................ 9...and constant emphasis on training in project management and acquisition, as well as in the SA-CMM. Figure 1: Managing Organizational Change Other

Regulation of matrix metalloproteinase-9 expression between gingival fibroblast cells from old and young rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Su-Jung; Chung, Yong-Koo; Chung, Tae-Wook

2009-01-09

Gingival fibroblast cells (rGF) from aged rats have an age-related decline in proliferative capacity compared with young rats. We investigated G1 phase cell cycle regulation and MMP-9 expression in both young and aged rGF. G1 cell cycle protein levels and activity were significantly reduced in response to interleukin-1{beta} (IL-1{beta}) stimulation with increasing in vitro age. Tumor necrosis factor-{alpha} (TNF-{alpha})-induced matrix metalloproteinase-9 (MMP-9) expression was also decreased in aged rGF in comparison with young rGF. Mutational analysis and gel shift assays demonstrated that the lower MMP-9 expression in aged rGF is associated with lower activities of transcription factors NF-{kappa}B and AP-1.more » These results suggest that cell cycle dysregulation and down-regulation of MMP-9 expression in rGF may play a role in gingival remodeling during in vitro aging.« less

Rho/ROCK signaling in regulation of corneal epithelial cell cycle progression.

PubMed

Chen, Jian; Guerriero, Emily; Lathrop, Kira; SundarRaj, Nirmala

2008-01-01

The authors' previous study showed that the expression of a Rho-associated serine/threonine kinase (ROCK) is regulated during cell cycle progression in corneal epithelial cells. The present study was conducted to determine whether and how Rho/ROCK signaling regulates cell cycle progression. Rabbit corneal epithelial cells (RCECs) in culture were arrested in the G(0) phase of the cell cycle by serum deprivation and then allowed to re-enter the cell cycle in the presence or absence of the ROCK inhibitor (Y27632) in serum-supplemented medium. The number of cells in the S phase, the relative levels of specific cyclins and CDKs and their intracellular distribution, and the relative levels of mRNAs were determined by BrdU labeling, Western blot and immunocytochemical analyses, and real-time RT-PCR, respectively. ROCK inhibition delayed the progression of G(1) to S phase and led to a decrease in the number of RCECs entering the S phase between 12 and 24 hours from 31.5% +/- 4.5% to 8.1% +/- 2.6%. During the cell cycle progression, protein and mRNA levels of cyclin-D1 and -D3 and cyclin-dependent kinases CDK4 and CDK6 were significantly lower, whereas the protein levels of the CDK inhibitor p27(Kip1) were higher in ROCK-inhibited cells. Intracellular mRNA or protein levels of cyclin-E and protein levels of CDK2 were not significantly affected, but their nuclear translocation was delayed by ROCK inhibition. ROCK signaling is involved in cell cycle progression in RCECs, possibly by upregulation of cyclin-D1 and -D3 and CDK4, -6, and -2; nuclear translocation of CDK2 and cyclin-E; and downregulation of p27(Kip1).

Regulation of cell division cycle progression by bcl-2 expression: a potential mechanism for inhibition of programmed cell death

PubMed Central

1996-01-01

Expression of the bcl-2 gene has been shown to effectively confer resistance to programmed cell death under a variety of circumstances. However, despite a wealth of literature describing this phenomenon, very little is known about the mechanism of resistance. In the experiments described here, we show that bcl-2 gene expression can result in an inhibition of cell division cycle progression. These findings are based upon the analysis of cell cycle distribution, cell cycle kinetics, and relative phosphorylation of the retinoblastoma tumor suppressor protein, using primary tissues in vivo, ex vivo, and in vitro, as well as continuous cell lines. The effects of bcl-2 expression on cell cycle progression appear to be focused at the G1 to S phase transition, which is a critical control point in the decision between continued cell cycle progression or the induction programmed cell death. In all systems tested, bcl-2 expression resulted in a substantial 30-60% increase in the length of G1 phase; such an increase is very substantial in the context of other regulators of cell cycle progression. Based upon our findings, and the related findings of others, we propose a mechanism by which bcl-2 expression might exert its well known inhibition of programmed cell death by regulating the kinetics of cell cycle progression at a critical control point. PMID:8642331

Relationships Between Social-Emotional Intelligence and Sexual Risk Behaviors in Adolescent Girls

PubMed Central

Lando-King, Elizabeth; McRee, Annie-Laurie; Gower, Amy L.; Shlafer, Rebecca J.; McMorris, Barbara J.; Pettingell, Sandra; Sieving, Renee E.

2015-01-01

Social-emotional intelligence (SEI) has been linked with a number of health behaviors in adolescent populations. However, little is known about the influence of SEI on sexual behavior. This study examined associations between three indicators of SEI (intrapersonal skills, interpersonal skills, stress management skills) and adolescent girls’ sexual risk behaviors. Data come from a cross-sectional sample of sexually active adolescent girls (ages 13 to 17 years) at high risk for pregnancy (N = 253), recruited from health care clinics in a Midwest metropolitan area during 2007 and 2008. Results of multivariable regression models controlling for participants’ age and race/ethnicity indicated that each aspect of SEI was related to distinct sexual risk behaviors. Specifically, girls with greater intrapersonal skills had significantly fewer male sex partners in the past six months (b = −0.16). Participants with greater interpersonal skills reported earlier communication with their sexual partner about sexual risk (b = 0.14), and those with a better ability to manage stress reported more consistent condom use (b = 0.31). Study findings suggest that SEI may provide a protective buffer against sexual risk behaviors. Building adolescent girls’ social and emotional skills may be an effective strategy for reducing their risk for early pregnancy and sexually transmitted infections. PMID:25621508

Proliferation of murine c-kit(pos) cardiac stem cells stimulated with IGF-1 is associated with Akt-1 mediated phosphorylation and nuclear export of FoxO3a and its effect on downstream cell cycle regulators.

PubMed

Johnson, Ann Mary; Kartha, C C

2014-04-01

Insulin-like growth factor-1 (IGF-1) is known to promote proliferation in many cell types including c-kit(pos) cardiac stem cells (CSCs). Downstream signaling pathways of IGF-1 induced CSC proliferation have not been investigated. An important downstream target of IGF-1/Akt-1 signaling is FoxO3a, a key negative regulator of cell-cycle progression. We studied the effect of IGF-1 on proliferation of c-kit(pos) murine CSCs and found that IGF-1-mediated cell proliferation is associated with FoxO3a phosphorylation and inactivation of its transcriptional activity. PI3 inhibitors LY294002 and Wortmannin abolished the effect of IGF-1 on FoxO3a phosphorylation indicating that FoxO3a phosphorylation is mediated by PI3/Akt-1 pathway. In cells with FoxO3a translocation to the cytoplasm, there is decreased expression of cell-cycle inhibitors such as p27(kip1) and p57(kip2) and increased expression of CyclinD1. Our study provides evidence that IGF-1 induced CSC proliferation could be the result of FoxO3a inactivation and its downstream effect on cell-cycle regulators.

Information Protection

DTIC Science & Technology

1987-07-01

changes for title page and front matter Version 1.1 (April 1987) slight cosmetic changes Version 1.0 (September 1986) original version iv SEI-CM-5-1.2...ramifications. The subject/object matrix is introduced as a method for understanding Fenton73 protection systems, and it is noteworthy that this Fenton , J

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peek, Gregory W.; Tollefsbol, Trygve O., E-mail: trygve@uab.edu; Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL

Human telomerase reverse transcriptase (hTERT) is the catalytic and limiting component of telomerase and also a transcription factor. It is critical to the integrity of the ends of linear chromosomes and to the regulation, extent and rate of cell cycle progression in multicellular eukaryotes. The level of hTERT expression is essential to a wide range of bodily functions and to avoidance of disease conditions, such as cancer, that are mediated in part by aberrant level and regulation of cell cycle proliferation. Value of a gene in regulation depends on its ability to both receive input from multiple sources and transmitmore » signals to multiple effectors. The expression of hTERT and the progression of the cell cycle have been shown to be regulated by an extensive network of gene products and signaling pathways, including the PI3K/Akt and TGF-β pathways. The PI3K inhibitor PX-866 and the competitive estrogen receptor ligand raloxifene have been shown to modify progression of those pathways and, in combination, to decrease proliferation of estrogen receptor positive (ER+) MCF-7 breast cancer cells. We found that combinations of modulators of those pathways decreased not only hTERT transcription but also transcription of additional essential cell cycle regulators such as Cyclin D1. By evaluating known expression profile signatures for TGF-β pathway diversions, we confirmed additional genes such as heparin-binding epidermal growth factor-like growth factor (HB EGF) by which those pathways and their perturbations may also modify cell cycle progression. - Highlights: • PX-866 and raloxifene affect the PI3K/Akt and TGF-β pathways. • PX-866 and raloxifene down-regulate genes up-regulated in cancer. • PX-866 and raloxifene decrease transcription of hTERT and Cyclin D1. • Pathological transcription signatures can identify new defense mechanisms.« less

Overexpression of Transcription Factor Sp1 Leads to Gene Expression Perturbations and Cell Cycle Inhibition

PubMed Central

Deniaud, Emmanuelle; Baguet, Joël; Chalard, Roxane; Blanquier, Bariza; Brinza, Lilia; Meunier, Julien; Michallet, Marie-Cécile; Laugraud, Aurélie; Ah-Soon, Claudette; Wierinckx, Anne; Castellazzi, Marc; Lachuer, Joël; Gautier, Christian

2009-01-01

Background The ubiquitous transcription factor Sp1 regulates the expression of a vast number of genes involved in many cellular functions ranging from differentiation to proliferation and apoptosis. Sp1 expression levels show a dramatic increase during transformation and this could play a critical role for tumour development or maintenance. Although Sp1 deregulation might be beneficial for tumour cells, its overexpression induces apoptosis of untransformed cells. Here we further characterised the functional and transcriptional responses of untransformed cells following Sp1 overexpression. Methodology and Principal Findings We made use of wild-type and DNA-binding-deficient Sp1 to demonstrate that the induction of apoptosis by Sp1 is dependent on its capacity to bind DNA. Genome-wide expression profiling identified genes involved in cancer, cell death and cell cycle as being enriched among differentially expressed genes following Sp1 overexpression. In silico search to determine the presence of Sp1 binding sites in the promoter region of modulated genes was conducted. Genes that contained Sp1 binding sites in their promoters were enriched among down-regulated genes. The endogenous sp1 gene is one of the most down-regulated suggesting a negative feedback loop induced by overexpressed Sp1. In contrast, genes containing Sp1 binding sites in their promoters were not enriched among up-regulated genes. These results suggest that the transcriptional response involves both direct Sp1-driven transcription and indirect mechanisms. Finally, we show that Sp1 overexpression led to a modified expression of G1/S transition regulatory genes such as the down-regulation of cyclin D2 and the up-regulation of cyclin G2 and cdkn2c/p18 expression. The biological significance of these modifications was confirmed by showing that the cells accumulated in the G1 phase of the cell cycle before the onset of apoptosis. Conclusion This study shows that the binding to DNA of overexpressed Sp1 induces an inhibition of cell cycle progression that precedes apoptosis and a transcriptional response targeting genes containing Sp1 binding sites in their promoter or not suggesting both direct Sp1-driven transcription and indirect mechanisms. PMID:19753117

Two inhibitory systems and CKIs regulate cell cycle exit of mammalian cardiomyocytes after birth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tane, Shoji; Okayama, Hitomi; Ikenishi, Aiko

Mammalian cardiomyocytes actively proliferate during embryonic stages, following which they exit their cell cycle after birth, and the exit is maintained. Previously, we showed that two inhibitory systems (the G1-phase inhibitory system: repression of cyclin D1 expression; the M-phase inhibitory system: inhibition of CDK1 activation) maintain the cell cycle exit of mouse adult cardiomyocytes. We also showed that two CDK inhibitors (CKIs), p21{sup Cip1} and p27{sup Kip1}, regulate the cell cycle exit in a portion of postnatal cardiomyocytes. It remains unknown whether the two inhibitory systems are involved in the cell cycle exit of postnatal cardiomyocytes and whether p21{sup Cip1}more » and p27{sup Kip1} also inhibit entry to M-phase. Here, we showed that more than 40% of cardiomyocytes entered an additional cell cycle by induction of cyclin D1 expression at postnatal stages, but M-phase entry was inhibited in the majority of cardiomyocytes. Marked cell cycle progression and endoreplication were observed in cardiomyocytes of p21{sup Cip1} knockout mice at 4 weeks of age. In addition, tri- and tetranucleated cardiomyocytes increased significantly in p21{sup Cip1} knockout mice. These data showed that the G1-phase inhibitory system and two CKIs (p21{sup Cip1} and p27{sup Kip1}) inhibit entry to an additional cell cycle in postnatal cardiomyocytes, and that the M-phase inhibitory system and p21{sup Cip1} inhibit M-phase entry of cardiomyocytes which have entered the additional cell cycle. - Highlights: • Many postnatal cardiomyocytes entered an additional cell cycle by cyclin D1 induction. • The majority of cardiomyocytes could not enter M-phase after cyclin D1 induction. • Cell cycle progressed markedly in p21{sup Cip1} knockout mice after postnatal day 14. • Tri- and tetranucleated cardiomyocytes increased in p21{sup Cip1} knockout mice.« less

Arabidopsis NUCLEOSTEMIN-LIKE 1 (NSN1) regulates cell cycling potentially by cooperating with nucleosome assembly protein AtNAP1;1.

PubMed

Wang, Zhen; Wang, Xiaomin; Xie, Bo; Hong, Zonglie; Yang, Qingchuan

2018-06-01

In mammals, nucleostemin (NS), a nucleolar GTPase, is involved in stem cell proliferation, embryogenesis and ribosome biogenesis. Arabidopsis NUCLEOSTEMIN-LIKE 1 (NSN1) has previously been shown to be essential for plant growth and development. However, the role of NSN1 in cell proliferation is largely unknown. Using nsn1, a loss-of-function mutant of Arabidopsis NSN1, we investigated the function of NSN1 in plant cell proliferation and cell cycle regulation. Morphologically, nsn1 exhibited developmental defects in both leaves and roots, producing severely reduced vegetative organs with a much smaller number of cells than those in the wild type. Dynamic analysis of leaf and root growth revealed a lower cell proliferation rate and slower cell division in nsn1. Consistently, the transcriptional levels of key cell  cycle genes, including those regulating the transition of G1-S and G2-M, were reduced drastically in nsn1. The introduction of CYCLIN B1::GUS into nsn1 resulted in confined expression of GUS in both the leaf primordia and root meristem, indicating that cell proliferation was hampered by the mutation of NSN1. Upon subjection to treatment with bleomycin and methyl methanesulfonate (MMS), nsn1 plants exhibited hypersensitivity to the genotoxic agents. In the nucleus, NSN1 interacted with nucleosome assembly protein1 (AtNAP1;1), a highly conserved histone chaperone functioning in cell proliferation. Notably, the N-terminal conserved domains of Arabidopsis NSN1 were critical for the physical interaction. As a conserved homolog of mammalian nucleostemin, Arabidopsis NSN1 plays pivotal roles in embryogenesis and ribosome biogenesis. In this study, NSN1 was found to function as a positive regulator in cell cycle progression. The interaction between NSN1 and histone chaperone AtNAP1;1, and the high resemblance in sensitivity to genotoxics between nsn1 and atnap1;1 imply the indispensability of the two nuclear proteins for cell cycle regulation. This work provides an insight into the delicate control of cell proliferation through the cooperation of a GTP-binding protein with a nucleosome assembly/disassembly protein in Arabidopsis.

Job titles classified into socioeconomic and occupational groups identify subjects with increased risk for respiratory symptoms independent of occupational exposure to vapour, gas, dust, or fumes.

PubMed

Schyllert, Christian; Andersson, Martin; Hedman, Linnea; Ekström, Magnus; Backman, Helena; Lindberg, Anne; Rönmark, Eva

2018-01-01

Objectives : To evaluate the ability of three different job title classification systems to identify subjects at risk for respiratory symptoms and asthma by also taking the effect of exposure to vapours, gas, dust, and fumes (VGDF) into account. Background : Respiratory symptoms and asthma may be caused by occupational factors. There are different ways to classify occupational exposure. In this study, self-reported occupational exposure to vapours, gas, dust and fumes was used as well as job titles classifed into occupational and socioeconomic Groups according to three different systems. Design: This was a large population-based study of adults aged 30-69 years in Northern Sweden ( n  = 9,992, 50% women). Information on job titles, VGDF-exposure, smoking habits, asthma and respiratory symptoms was collected by a postal survey. Job titles were used for classification into socioeconomic and occupational groups based on three classification systems; Socioeconomic classification (SEI), the Nordic Occupations Classification 1983 (NYK), and the Swedish Standard Classification of Occupations 2012 (SSYK). Associations were analysed by multivariable logistic regression. Results : Occupational exposure to VGDF was a risk factor for all respiratory symptoms and asthma (odds ratios (ORs) 1.3-2.4). Productive cough was associated with the socioeconomic groups of manual workers (ORs 1.5-2.1) and non-manual employees (ORs 1.6-1.9). These groups include occupations such as construction and transportation workers, service workers, nurses, teachers and administration clerks which by the SSYK classification were associated with productive cough (ORs 2.4-3.7). Recurrent wheeze was significantly associated with the SEI group manual workers (ORs 1.5-1.7). After adjustment for also VGDF, productive cough remained significantly associated with the SEI groups manual workers in service and non-manual employees, and the SSYK-occupational groups administration, service, and elementary occupations. Conclusions : In this cross-sectional study, two of the three different classification systems, SSYK and SEI gave similar results and identified groups with increased risk for respiratory symptoms while NYK did not give conclusive results. Furthermore, several associations were independent of exposure to VGDF indicating that also other job-related factors than VGDF are of importance.

40 CFR 86.1309-90 - Exhaust gas sampling system; Otto-cycle and non-petroleum-fueled engines.

Code of Federal Regulations, 2010 CFR

2010-07-01

...-cycle and non-petroleum-fueled engines. 86.1309-90 Section 86.1309-90 Protection of Environment... HIGHWAY VEHICLES AND ENGINES (CONTINUED) Emission Regulations for New Otto-Cycle and Diesel Heavy-Duty...-cycle and non-petroleum-fueled engines. (a)(1) General. The exhaust gas sampling system described in...

Quantitative Cell Cycle Analysis Based on an Endogenous All-in-One Reporter for Cell Tracking and Classification.

PubMed

Zerjatke, Thomas; Gak, Igor A; Kirova, Dilyana; Fuhrmann, Markus; Daniel, Katrin; Gonciarz, Magdalena; Müller, Doris; Glauche, Ingmar; Mansfeld, Jörg

2017-05-30

Cell cycle kinetics are crucial to cell fate decisions. Although live imaging has provided extensive insights into this relationship at the single-cell level, the limited number of fluorescent markers that can be used in a single experiment has hindered efforts to link the dynamics of individual proteins responsible for decision making directly to cell cycle progression. Here, we present fluorescently tagged endogenous proliferating cell nuclear antigen (PCNA) as an all-in-one cell cycle reporter that allows simultaneous analysis of cell cycle progression, including the transition into quiescence, and the dynamics of individual fate determinants. We also provide an image analysis pipeline for automated segmentation, tracking, and classification of all cell cycle phases. Combining the all-in-one reporter with labeled endogenous cyclin D1 and p21 as prime examples of cell-cycle-regulated fate determinants, we show how cell cycle and quantitative protein dynamics can be simultaneously extracted to gain insights into G1 phase regulation and responses to perturbations. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Cell Cycle Regulates Nuclear Stability of AID and Determines the Cellular Response to AID

PubMed Central

Le, Quy; Maizels, Nancy

2015-01-01

AID (Activation Induced Deaminase) deaminates cytosines in DNA to initiate immunoglobulin gene diversification and to reprogram CpG methylation in early development. AID is potentially highly mutagenic, and it causes genomic instability evident as translocations in B cell malignancies. Here we show that AID is cell cycle regulated. By high content screening microscopy, we demonstrate that AID undergoes nuclear degradation more slowly in G1 phase than in S or G2-M phase, and that mutations that affect regulatory phosphorylation or catalytic activity can alter AID stability and abundance. We directly test the role of cell cycle regulation by fusing AID to tags that destabilize nuclear protein outside of G1 or S-G2/M phases. We show that enforced nuclear localization of AID in G1 phase accelerates somatic hypermutation and class switch recombination, and is well-tolerated; while nuclear AID compromises viability in S-G2/M phase cells. We identify AID derivatives that accelerate somatic hypermutation with minimal impact on viability, which will be useful tools for engineering genes and proteins by iterative mutagenesis and selection. Our results further suggest that use of cell cycle tags to regulate nuclear stability may be generally applicable to studying DNA repair and to engineering the genome. PMID:26355458

The Ubiquitin Ligase SCF(Ucc1) Acts as a Metabolic Switch for the Glyoxylate Cycle.

PubMed

Nakatsukasa, Kunio; Nishimura, Takashi; Byrne, Stuart D; Okamoto, Michiyo; Takahashi-Nakaguchi, Azusa; Chibana, Hiroji; Okumura, Fumihiko; Kamura, Takumi

2015-07-02

Despite the crucial role played by the glyoxylate cycle in the virulence of pathogens, seed germination in plants, and sexual development in fungi, we still have much to learn about its regulation. Here, we show that a previously uncharacterized SCF(Ucc1) ubiquitin ligase mediates proteasomal degradation of citrate synthase in the glyoxylate cycle to maintain metabolic homeostasis in glucose-grown cells. Conversely, transcription of the F box subunit Ucc1 is downregulated in C2-compound-grown cells, which require increased metabolic flux for gluconeogenesis. Moreover, in vitro analysis demonstrates that oxaloacetate regenerated through the glyoxylate cycle induces a conformational change in citrate synthase and inhibits its recognition and ubiquitination by SCF(Ucc1), suggesting the existence of an oxaloacetate-dependent positive feedback loop that stabilizes citrate synthase. We propose that SCF(Ucc1)-mediated regulation of citrate synthase acts as a metabolic switch for the glyoxylate cycle in response to changes in carbon source, thereby ensuring metabolic versatility and flexibility. Copyright © 2015 Elsevier Inc. All rights reserved.

Cluster-search based monitoring of local earthquakes in SeisComP3

NASA Astrophysics Data System (ADS)

Roessler, D.; Becker, J.; Ellguth, E.; Herrnkind, S.; Weber, B.; Henneberger, R.; Blanck, H.

2016-12-01

We present a new cluster-search based SeisComP3 module for locating local and regional earthquakes in real time. Real-time earthquake monitoring systems such as SeisComP3 provide the backbones for earthquake early warning (EEW), tsunami early warning (TEW) and the rapid assessment of natural and induced seismicity. For any earthquake monitoring system fast and accurate event locations are fundamental determining the reliability and the impact of further analysis. SeisComP3 in the OpenSource version includes a two-stage detector for picking P waves and a phase associator for locating earthquakes based on P-wave detections. scanloc is a more advanced earthquake location program developed by gempa GmbH with seamless integration into SeisComP3. scanloc performs advanced cluster search to discriminate earthquakes occurring closely in space and time and makes additional use of S-wave detections. It has proven to provide fast and accurate earthquake locations at local and regional distances where it outperforms the base SeisComP3 tools. We demonstrate the performance of scanloc for monitoring induced seismicity as well as local and regional earthquakes in different tectonic regimes including subduction, spreading and intra-plate regions. In particular we present examples and catalogs from real-time monitoring of earthquake in Northern Chile based on data from the IPOC network by GFZ German Research Centre for Geosciences for the recent years. Depending on epicentral distance and data transmission, earthquake locations are available within a few seconds after origin time when using scanloc. The association of automatic S-wave detections provides a better constraint on focal depth.

MicroRNA-139-5p acts as a tumor suppressor by targeting ELTD1 and regulating cell cycle in glioblastoma multiforme

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Shouping; Wang, Xianjun; Li, Xiao

MicroRNA-139-5p was identified to be significantly down-regulated in glioblastoma multiform (GBM) by miRNA array. In this report we aimed to clarify its biological function, molecular mechanisms and direct target gene in GBM. Twelve patients with GBM were analyzed for the expression of miR-139-5p by quantitative RT-PCR. miR-139-5p overexpression was established by transfecting miR-139-5p-mimic into U87MG and T98G cells, and its effects on cell proliferation were studied using MTT assay and colony formation assays. We concluded that ectopic expression of miR-139-5p in GBM cell lines significantly suppressed cell proliferation and inducing apoptosis. Bioinformatics coupled with luciferase and western blot assays alsomore » revealed that miR-139-5p suppresses glioma cell proliferation by targeting ELTD1 and regulating cell cycle. - Highlights: • miR-139-5p is downregulated in GBM. • miR-139-5p regulates cell proliferation through inducing apoptosis. • miR-139-5p regulates glioblastoma tumorigenesis by targeting 3′UTR of ELTD1. • miR-139-5p is involved in cell cycle regulation.« less

Microscale Alloy Type Lithium Ion Battery Anodes

DTIC Science & Technology

2015-09-01

hexamethyldisilazane Li lithium Ni nickel NMP n-methyl-2-pyrolidone RMS root mean square SEI solid electrolyte interphase SEM scanning electron microscopy...process also leads to an unstable solid electrolyte interphase (SEI) and further capacity loss. An extraordinary amount of work has been done in an...

77 FR 56613 - Marine Mammals; File No. 16325

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-13

.... musculus), sei whales (B. borealis), minke whales (B. acutorostrata), sperm whales (Physeter macrocephalus...). The permit authorizes harassment of humpback, fin, blue, sei, minke, sperm and killer whales by close... the quality of the human environment and that preparation of an environmental impact statement was not...

SeisFlows-Flexible waveform inversion software

NASA Astrophysics Data System (ADS)

Modrak, Ryan T.; Borisov, Dmitry; Lefebvre, Matthieu; Tromp, Jeroen

2018-06-01

SeisFlows is an open source Python package that provides a customizable waveform inversion workflow and framework for research in oil and gas exploration, earthquake tomography, medical imaging, and other areas. New methods can be rapidly prototyped in SeisFlows by inheriting from default inversion or migration classes, and code can be tested on 2D examples before application to more expensive 3D problems. Wave simulations must be performed using an external software package such as SPECFEM3D. The ability to interface with external solvers lends flexibility, and the choice of SPECFEM3D as a default option provides optional GPU acceleration and other useful capabilities. Through support for massively parallel solvers and interfaces for high-performance computing (HPC) systems, inversions with thousands of seismic traces and billions of model parameters can be performed. So far, SeisFlows has run on clusters managed by the Department of Defense, Chevron Corp., Total S.A., Princeton University, and the University of Alaska, Fairbanks.

The Space Environmental Impact System

NASA Astrophysics Data System (ADS)

Kihn, E. A.

2009-12-01

The Space Environmental Impact System (SEIS) is an operational tool for incorporating environmental data sets into DoD Modeling and Simulation (M&S) which allows for enhanced decision making regarding acquisitions, testing, operations and planning. The SEIS system creates, from the environmental archives and developed rule-base, a tool for describing the effects of the space environment on particular military systems, both historically and in real-time. The system uses data available over the web, and in particular data provided by NASA’s virtual observatory network, as well as modeled data generated specifically for this purpose. The rule base system developed to support SEIS is an open XML based model which can be extended to events from any environmental domain. This presentation will show how the SEIS tool allows users to easily and accurately evaluate the effect of space weather in terms that are meaningful to them as well as discuss the relevant standards used in its construction and go over lessons learned from fielding an operational environmental decision tool.

Estimation of carrier leakage in InGaN light emitting diodes from photocurrent measurements

NASA Astrophysics Data System (ADS)

Hafiz, Shopan; Zhang, Fan; Monavarian, Morteza; Okur, Serdal; Avrutin, Vitaliy; Morkoç, Hadis; Özgür, Ümit

2014-02-01

Carrier transport in double heterostructure (DH) InGaN light emitting diodes (LEDs) was investigated using photocurrent measurements performed under CW HeCd laser (325 nm wavelength) excitation. The effect of electron injector thicknesses was investigated by monitoring the excitation density and applied bias dependent escape of photogenerated carriers from the active region and through energy band structure and carrier transport simulations using Silvaco Atlas. For quad (4x) 3-nm DH LED structures incorporating staircase electron injectors (SEIs), photocurrent increased with SEI thickness due to reduced effective barrier opposing carrier escape from the active region as confirmed by simulations. The carrier leakage percentile at -3V bias and 280 Wcm-2 optical excitation density increased from 24 % to 55 % when In 0.04Ga0.96N + In0.08Ga0.92N SEI thickness was increased from 4 nm + 4 nm to 30 nm + 30 nm. The increased leakage with thicker SEI correlates with increased carrier overflow under forward bias.

Human immunodeficiency virus type 1 envelope proteins traffic toward virion assembly sites via a TBC1D20/Rab1-regulated pathway

PubMed Central

2012-01-01

Background The cellular activity of many factors and pathways is required to execute the complex replication cycle of the human immunodeficiency virus type 1 (HIV-1). To reveal these cellular components, several extensive RNAi screens have been performed, listing numerous 'HIV-dependency factors'. However, only a small overlap between these lists exists, calling for further evaluation of the relevance of specific factors to HIV-1 replication and for the identification of additional cellular candidates. TBC1D20, the GTPase-activating protein (GAP) of Rab1, regulates endoplasmic reticulum (ER) to Golgi trafficking, was not identified in any of these screens, and its involvement in HIV-1 replication cycle is tested here. Findings Excessive TBC1D20 activity perturbs the early trafficking of HIV-1 envelope protein through the secretory pathway. Overexpression of TBC1D20 hampered envelope processing and reduced its association with detergent-resistant membranes, entailing a reduction in infectivity of HIV-1 virion like particles (VLPs). Conclusions These findings add TBC1D20 to the network of host factors regulating HIV replication cycle. PMID:22260459

C/EBPα regulates CRL4Cdt2-mediated degradation of p21 in response to UVB-induced DNA damage to control the G1/S checkpoint

PubMed Central

Hall, Jonathan R; Bereman, Michael S; Nepomuceno, Angelito I; Thompson, Elizabeth A; Muddiman, David C; Smart, Robert C

2014-01-01

The bZIP transcription factor, C/EBPα is highly inducible by UVB and other DNA damaging agents in keratinocytes. C/EBPα-deficient keratinocytes fail to undergo cell cycle arrest in G1 in response to UVB-induced DNA damage and mice lacking epidermal C/EBPα are highly susceptible to UVB-induced skin cancer. The mechanism through which C/EBPα regulates the cell cycle checkpoint in response to DNA damage is unknown. Here we report untreated C/EBPα-deficient keratinocytes have normal levels of the cyclin-dependent kinase inhibitor, p21, however, UVB-treated C/EBPα-deficient keratinocytes fail to up-regulate nuclear p21 protein levels despite normal up-regulation of Cdkn1a mRNA levels. UVB-treated C/EBPα-deficient keratinocytes displayed a 4-fold decrease in nuclear p21 protein half-life due to the increased proteasomal degradation of p21 via the E3 ubiquitin ligase CRL4Cdt2. Cdt2 is the substrate recognition subunit of CRL4Cdt2 and Cdt2 mRNA and protein levels were up-regulated in UVB-treated C/EBPα-deficient keratinocytes. Knockdown of Cdt2 restored p21 protein levels in UVB-treated C/EBPα-deficient keratinocytes. Lastly, the failure to accumulate p21 in response to UVB in C/EBPα-deficient keratinocytes resulted in decreased p21 interactions with critical cell cycle regulatory proteins, increased CDK2 activity, and inappropriate entry into S-phase. These findings reveal C/EBPα regulates G1/S cell cycle arrest in response to DNA damage via the control of CRL4Cdt2 mediated degradation of p21. PMID:25483090

Chloroplast Dysfunction Causes Multiple Defects in Cell Cycle Progression in the Arabidopsis crumpled leaf Mutant1[C][W

PubMed Central

Hudik, Elodie; Yoshioka, Yasushi; Domenichini, Séverine; Bourge, Mickaël; Soubigout-Taconnat, Ludivine; Mazubert, Christelle; Yi, Dalong; Bujaldon, Sandrine; Hayashi, Hiroyuki; De Veylder, Lieven; Bergounioux, Catherine; Benhamed, Moussa; Raynaud, Cécile

2014-01-01

The majority of research on cell cycle regulation is focused on the nuclear events that govern the replication and segregation of the genome between the two daughter cells. However, eukaryotic cells contain several compartmentalized organelles with specialized functions, and coordination among these organelles is required for proper cell cycle progression, as evidenced by the isolation of several mutants in which both organelle function and overall plant development were affected. To investigate how chloroplast dysfunction affects the cell cycle, we analyzed the crumpled leaf (crl) mutant of Arabidopsis (Arabidopsis thaliana), which is deficient for a chloroplastic protein and displays particularly severe developmental defects. In the crl mutant, we reveal that cell cycle regulation is altered drastically and that meristematic cells prematurely enter differentiation, leading to reduced plant stature and early endoreduplication in the leaves. This response is due to the repression of several key cell cycle regulators as well as constitutive activation of stress-response genes, among them the cell cycle inhibitor SIAMESE-RELATED5. One unique feature of the crl mutant is that it produces aplastidic cells in several organs, including the root tip. By investigating the consequence of the absence of plastids on cell cycle progression, we showed that nuclear DNA replication occurs in aplastidic cells in the root tip, which opens future research prospects regarding the dialogue between plastids and the nucleus during cell cycle regulation in higher plants. PMID:25037213

Systems-level feedback regulation of cell cycle transitions in Ostreococcus tauri.

PubMed

Kapuy, Orsolya; Vinod, P K; Bánhegyi, Gábor; Novák, Béla

2018-05-01

Ostreococcus tauri is the smallest free-living unicellular organism with one copy of each core cell cycle genes in its genome. There is a growing interest in this green algae due to its evolutionary origin. Since O. tauri is diverged early in the green lineage, relatively close to the ancestral eukaryotic cell, it might hold a key phylogenetic position in the eukaryotic tree of life. In this study, we focus on the regulatory network of its cell division cycle. We propose a mathematical modelling framework to integrate the existing knowledge of cell cycle network of O. tauri. We observe that feedback loop regulation of both G1/S and G2/M transitions in O. tauri is conserved, which can make the transition bistable. This is essential to make the transition irreversible as shown in other eukaryotic organisms. By performing sequence analysis, we also predict the presence of the Greatwall/PP2A pathway in the cell cycle of O. tauri. Since O. tauri cell cycle machinery is conserved, the exploration of the dynamical characteristic of the cell division cycle will help in further understanding the regulation of cell cycle in higher eukaryotes. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Mechanically and chemically robust sandwich-structured C@Si@C nanotube array Li-ion battery anodes.

PubMed

Liu, Jinyun; Li, Nan; Goodman, Matthew D; Zhang, Hui Gang; Epstein, Eric S; Huang, Bo; Pan, Zeng; Kim, Jinwoo; Choi, Jun Hee; Huang, Xingjiu; Liu, Jinhuai; Hsia, K Jimmy; Dillon, Shen J; Braun, Paul V

2015-02-24

Stability and high energy densities are essential qualities for emerging battery electrodes. Because of its high specific capacity, silicon has been considered a promising anode candidate. However, the several-fold volume changes during lithiation and delithiation leads to fractures and continuous formation of an unstable solid-electrolyte interphase (SEI) layer, resulting in rapid capacity decay. Here, we present a carbon-silicon-carbon (C@Si@C) nanotube sandwich structure that addresses the mechanical and chemical stability issues commonly associated with Si anodes. The C@Si@C nanotube array exhibits a capacity of ∼2200 mAh g(-1) (∼750 mAh cm(-3)), which significantly exceeds that of a commercial graphite anode, and a nearly constant Coulombic efficiency of ∼98% over 60 cycles. In addition, the C@Si@C nanotube array gives much better capacity and structure stability compared to the Si nanotubes without carbon coatings, the ZnO@C@Si@C nanorods, a Si thin film on Ni foam, and C@Si and Si@C nanotubes. In situ SEM during cycling shows that the tubes expand both inward and outward upon lithiation, as well as elongate, and then revert back to their initial size and shape after delithiation, suggesting stability during volume changes. The mechanical modeling indicates the overall plastic strain in a nanotube is much less than in a nanorod, which may significantly reduce low-cycle fatigue. The sandwich-structured nanotube design is quite general, and may serve as a guide for many emerging anode and cathode systems.

Abuse Tolerance Improvements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orendorff, Christopher J.; Nagasubramanian, Ganesan; Fenton, Kyle R.

As lithium-ion battery technologies mature, the size and energy of these systems continues to increase (> 50 kWh for EVs); making safety and reliability of these high energy systems increasingly important. While most material advances for lithium-ion chemistries are directed toward improving cell performance (capacity, energy, cycle life, etc.), there are a variety of materials advancements that can be made to improve lithium-ion battery safety. Issues including energetic thermal runaway, electrolyte decomposition and flammability, anode SEI stability, and cell-level abuse tolerance continue to be critical safety concerns. This report highlights work with our collaborators to develop advanced materials to improvemore » lithium-ion battery safety and abuse tolerance and to perform cell-level characterization of new materials.« less

The BMI1 inhibitor PTC-209 is a potential compound to halt cellular growth in biliary tract cancer cells

PubMed Central

Mayr, Christian; Wagner, Andrej; Loeffelberger, Magdalena; Bruckner, Daniela; Jakab, Martin; Berr, Frieder; Di Fazio, Pietro; Ocker, Matthias; Neureiter, Daniel; Pichler, Martin; Kiesslich, Tobias

2016-01-01

BMI1 is a core component of the polycomb repressive complex 1 (PRC1) and is up-regulated in biliary tract cancer (BTC), contributing to aggressive clinical features. In this study we investigated the cytotoxic effects of PTC-209, a recently developed inhibitor of BMI1, in BTC cells. PTC-209 reduced overall viability in BTC cell lines in a dose-dependent fashion (0.04 - 20 μM). Treatment with PTC-209 led to slightly enhanced caspase activity and stop of cell proliferation. Cell cycle analysis revealed that PTC-209 caused cell cycle arrest at the G1/S checkpoint. A comprehensive investigation of expression changes of cell cycle-related genes showed that PTC-209 caused significant down-regulation of cell cycle-promoting genes as well as of genes that contribute to DNA synthesis initiation and DNA repair, respectively. This was accompanied by significantly elevated mRNA levels of cell cycle inhibitors. In addition, PTC-209 reduced sphere formation and, in a cell line-dependent manner, aldehyde dehydrogease-1 positive cells. We conclude that PTC-209 might be a promising drug for future in vitro and in vivo studies in BTC. PMID:26623561

Glutathione transferases P1/P2 regulate the timing of signaling pathway activations and cell cycle progression during mouse liver regeneration

PubMed Central

Pajaud, J; Ribault, C; Ben Mosbah, I; Rauch, C; Henderson, C; Bellaud, P; Aninat, C; Loyer, P; Morel, F; Corlu, A

2015-01-01

Glutathione transferases (GST) are phase II enzymes catalyzing the detoxification of endogenous noxious compounds and xenobiotics. They also regulate phosphorylation activities of MAPKinases in a catalytic-independent manner. Previous studies have demonstrated the regulation of JNK-dependent pathway by GSTP1/2. Considering the crucial role of JNK in the early steps of the hepatocyte cell cycle, we sought to determine whether GSTP1/2 were essential for hepatocyte proliferation following partial hepatectomy (PH). Using a conventional double knockout mouse model for the Gstp1 and Gstp2 genes, we found that the lack of GSTP1/P2 reduced the rate of DNA replication and mitotic index during the first wave of hepatocyte proliferation. The lowered proliferation was associated with the decrease in TNFalpha and IL-6 plasma concentrations, reduced hepatic HGF expression and delayed and/or altered activation of STAT3, JNK and ERK1/2 signaling pathways. In addition, the expression and/or activation of cell cycle regulators such as Cyclin D1, CDK4, E2F1 and MCM7 was postponed demonstrating that the absence of GSTP1/2 delayed the entry into and progression through the G1 phase of the cell cycle and impaired the synchrony of proliferation in hepatocytes following PH. Furthermore, while JNK and its downstream targets c-Jun and ATF2 were activated during the early steps of the liver regeneration in wild-type animals, the constitutively active JNK found in the quiescent liver of Gstp1/2 knockout mice underwent a decrease in its activity after PH. Transient induction of antioxidant enzymes and nitric oxide synthase were also delayed or repressed during the regenerative response. Altogether our results demonstrate that GSTP1/2 are a critical regulators of hepatocyte proliferation in the initial phases of liver regeneration. PMID:25590808

Regulation of post-translational protein arginine methylation during HeLa cell cycle.

PubMed

Kim, Chongtae; Lim, Yongchul; Yoo, Byong Chul; Won, Nam Hee; Kim, Sangduk; Kim, Gieun

2010-09-01

Post-translational arginine methylation which modifies protein-arginyl residues by protein arginine methyltransferase (PRMT) was investigated during synchronized HeLa cell cycle. The lysates of cells synchronized at each stage were subjected to one and/or two dimensional electrophoresis followed by Western immunoblot using against anti-asymmetric-dimethyl-arginine (ASYM24), anti-symmetric-dimethyl-arginine (SYM10), and subclasses of PRMTs, including PRMT1, PRMT3, PRMT4 (CARM1), PRMT5, PRMT6, and PRMT7 antibodies. Proteins with approximate molecular masses of 80 kDa, 68 kDa, and 64 kDa, containing asymmetric-dimethyl-arginine (aDMA) were increased at G0/G1 to G1, which lasted until S phase. In addition, 25 kDa protein of symmetric-dimethyl-arginine (sDMA) was also markedly up-regulated from G0/G1 to G1. The levels of PRMT3, PRMT6 and PRMT7 were concurrently increased during the cell cycle. Two-dimensional gel electrophoresis followed by MALDI-TOF-MS was identified as aDMA-80 kDa and aDMA-68 kDa proteins as heterogeneous nuclear ribonucleoprotein R (hnRNPR), aDMA-64 kDa proteins as cleavage stimulation factor 64 kDa subunit (CstF-64), and sDMA-25 kDa protein as triosephosphate isomerase (TPI). The levels of increased aDMA of hnRNPR were reduced, when HeLa cells were transfected with siRNA for PRMT1, and the aDMA of CstF-64 with siRNA for PRMT3, while depletion of PRMT5 down-regulated sDMA of TPI. Protein arginine dimethylations of hnRNPR, CstF-64, and TPI were regulated during HeLa cell cycle by respective PRMTs. These results suggest that regulation of arginine dimethylation of hnRNPR, CstF-64, and TPI at G0/G1 to G1 are most likely to modulate the cellular growth and proliferation in HeLa cell cycle. Copyright © 2010 Elsevier B.V. All rights reserved.

Cell cycle sibling rivalry: Cdc2 vs. Cdk2.

PubMed

Kaldis, Philipp; Aleem, Eiman

2005-11-01

It has been long believed that the cyclin-dependent kinase 2 (Cdk2) binds to cyclin E or cyclin A and exclusively promotes the G1/S phase transition and that Cdc2/cyclin B complexes play a major role in mitosis. We now provide evidence that Cdc2 binds to cyclin E (in addition to cyclin A and B) and is able to promote the G1/S transition. This new concept indicates that both Cdk2 and/or Cdc2 can drive cells through G1/S phase in parallel. In this review we discuss the classic cell cycle model and how results from knockout mice provide new evidence that refute this model. We focus on the roles of Cdc2 and p27 in regulating the mammalian cell cycle and propose a new model for cell cycle regulation that accommodates these novel findings.

75 FR 65005 - Intent To Prepare a Draft Supplemental Environmental Impact Statement (SEIS), Mississippi Barrier...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-21

... Supplemental Environmental Impact Statement (SEIS), Mississippi Barrier Island Restoration, Mississippi Coastal... reduction, shoreline erosion, salt water intrusion and fish and wildlife preservation in three coastal... catastrophic damage to lives, property, and natural resources throughout coastal Mississippi. In response, the...

77 FR 27719 - Marine Mammals; File Nos. 16109 and 15575

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-11

... (Megaptera novaeangliae), North Atlantic right whale (Eubalaena glacialis), sei whale (B. borealis), sperm..., sei whale, sperm whale, green sea turtle, hawksbill sea turtle, loggerhead sea turtle, Kemp's ridley... in the EA, NMFS determined that issuance of the permits would not significantly impact the quality of...

Protein tyrosine phosphatase of liver regeneration-1 is required for normal timing of cell cycle progression during liver regeneration

PubMed Central

Jiao, Yang; Ye, Diana Z.; Li, Zhaoyu; Teta-Bissett, Monica; Peng, Yong; Taub, Rebecca; Greenbaum, Linda E.

2014-01-01

Protein tyrosine phosphatase of liver regeneration-1 (Prl-1) is an immediate-early gene that is significantly induced during liver regeneration. Several in vitro studies have suggested that Prl-1 is important for the regulation of cell cycle progression. To evaluate its function in liver regeneration, we ablated the Prl-1 gene specifically in mouse hepatocytes using the Cre-loxP system. Prl-1 mutant mice (Prl-1loxP/loxP;AlfpCre) appeared normal and fertile. Liver size and metabolic function in Prl-1 mutants were comparable to controls, indicating that Prl-1 is dispensable for liver development, postnatal growth, and hepatocyte differentiation. Mutant mice demonstrated a delay in DNA synthesis after 70% partial hepatectomy, although ultimate liver mass restoration was not affected. At 40 h posthepatectomy, reduced protein levels of the cell cycle regulators cyclin E, cyclin A2, cyclin B1, and cyclin-dependent kinase 1 were observed in Prl-1 mutant liver. Investigation of the major signaling pathways involved in liver regeneration demonstrated that phosphorylation of protein kinase B (AKT) and signal transducer and activator of transcription (STAT) 3 were significantly reduced at 40 h posthepatectomy in Prl-1 mutants. Taken together, this study provides evidence that Prl-1 is required for proper timing of liver regeneration after partial hepatectomy. Prl-1 promotes G1/S progression via modulating expression of several cell cycle regulators through activation of the AKT and STAT3 signaling pathway. PMID:25377314

Rare sugar D-allose induces specific up-regulation of TXNIP and subsequent G1 cell cycle arrest in hepatocellular carcinoma cells by stabilization of p27kip1.

PubMed

Yamaguchi, Fuminori; Takata, Maki; Kamitori, Kazuyo; Nonaka, Machiko; Dong, Youyi; Sui, Li; Tokuda, Masaaki

2008-02-01

'Rare sugars' are defined as monosaccharides that exist in nature but are only present in limited quantities. The development of mass production method of rare sugars revealed some interesting physiological effects of these on animal cells, but the mechanisms have not been well studied. We examined the effect of D-allose on the proliferation of cancer cells and the underlying molecular mechanism of the action. The HuH-7 hepatocellular carcinoma cells were treated with various monosaccharides for 48 h and D-allose was shown to inhibit cell growth by 40% in a dose-dependent manner. D-allose induced G1 cell cycle arrest but not apoptosis. The microarray analysis revealed that D-allose significantly up-regulated thioredoxin interacting protein (TXNIP) gene expression, which is often suppressed in tumor cells and western blot analysis confirmed its increase at protein level. The overexpression of TXNIP also induced G1 cell cycle arrest. Analysis of cell cycle regulatory genes showed p27kip1, a key regulator of G1/S cell cycle transition, to be increased at the protein but not the transcriptional level. Protein interaction between TXNIP and jab1, and p27kip1 and jab1, was observed, suggesting stabilization of p27kip1 protein by the competitive inhibition of jab1-mediated nuclear export of p27kip1 by TXNIP. In addition, increased interaction and nuclear localization of TXNIP and p27kip1 were apparent after D-allose treatment. Our findings surprisingly suggest that D-allose, a simple monosaccharide, may act as a novel anticancer agent via unique TXNIP induction and p27kip1 protein stabilization.

The Effect of Fluoroethylene Carbonate as an Additive on the Solid Electrolyte Interphase on Silicon Lithium-Ion Electrodes

DOE PAGES

Schroder, Kjell; Li, Juchuan; Dudney, Nancy J.; ...

2015-08-03

Fluoroethylene carbonate (FEC) has become a standard electrolyte additive for use with silicon negative electrodes, but how FEC affects solid electrolyte interphase (SEI) formation on the silicon anode’s surface is still not well understood. Herein, SEI formed from LiPF6-based carbonate electrolytes, with and without FEC, were investigated on 50 nm thick amorphous silicon thin film electrodes to understand the role of FEC on silicon electrode surface reactions. In contrast to previous work, anhydrous and anoxic techniques were used to prevent air and moisture contamination of prepared SEI films. This allowed for accurate characterization of the SEI structure and composition bymore » X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry depth profiling. These results show that FEC reduction leads to fluoride ion and LiF formation, consistent with previous computational and experimental results. Surprisingly, we also find that these species decrease lithium-ion solubility and increase the reactivity of the silicon surface. We conclude that the effectiveness of FEC at improving the Coulombic efficiency and capacity retention is due to fluoride ion formation from reduction of the electrolyte, which leads to the chemical attack of any silicon-oxide surface passivation layers and the formation of a kinetically stable SEI comprising predominately lithium fluoride and lithium oxide.« less

Cancer dormancy and cell signaling: Induction of p21waf1 initiated by membrane IgM engagement increases survival of B lymphoma cells

PubMed Central

Marches, Radu; Hsueh, Robert; Uhr, Jonathan W.

1999-01-01

The p21WAF1 (p21) cyclin-dependent kinase inhibitor plays a major role in regulating cell cycle arrest. It was recently reported that the p53-independent elevation of p21 protein levels is essential in mediating the G1 arrest resulting from signal transduction events initiated by the crosslinking of membrane IgM on Daudi Burkitt lymphoma cells. Although the role of p21 in cell cycle regulation is well documented, there is little information concerning its role in antibody-mediated apoptosis. In the present study, we examined the involvement of p21 in the regulation of apoptosis by suppressing its induction in anti-IgM-treated Daudi cells through a p21 antisense expression construct approach. Reduction in induced p21 protein levels resulted in diminished G1 arrest and increased apoptosis. The increased susceptibility to anti-IgM-mediated apoptosis was associated with increased caspase-3-like activity and poly-(ADP)ribose polymerase cleavage. These data suggest that p21 may directly interfere with the caspase cascade, thus playing a dual role in regulating both cell cycle progression and apoptosis. PMID:10411940

SmgGDS is a transient nucleolar protein that protects cells from nucleolar stress and promotes the cell cycle by regulating DREAM complex gene expression.

PubMed

Gonyo, P; Bergom, C; Brandt, A C; Tsaih, S-W; Sun, Y; Bigley, T M; Lorimer, E L; Terhune, S S; Rui, H; Flister, M J; Long, R M; Williams, C L

2017-12-14

The chaperone protein and guanine nucleotide exchange factor SmgGDS (RAP1GDS1) is a key promoter of cancer cell proliferation and tumorigenesis. SmgGDS undergoes nucleocytoplasmic shuttling, suggesting that it has both cytoplasmic and nuclear functions that promote cancer. Previous studies indicate that SmgGDS binds cytoplasmic small GTPases and promotes their trafficking to the plasma membrane. In contrast, little is known about the functions of SmgGDS in the nucleus, or how these nuclear functions might benefit cancer cells. Here we show unique nuclear localization and regulation of gene transcription pathways by SmgGDS. Strikingly, SmgGDS depletion significantly reduces expression of over 600 gene products that are targets of the DREAM complex, which is a transcription factor complex that regulates expression of proteins controlling the cell cycle. The cell cycle regulators E2F1, MYC, MYBL2 (B-Myb) and FOXM1 are among the DREAM targets that are diminished by SmgGDS depletion. E2F1 is well known to promote G1 cell cycle progression, and the loss of E2F1 in SmgGDS-depleted cells provides an explanation for previous reports that SmgGDS depletion characteristically causes a G1 cell cycle arrest. We show that SmgGDS localizes in nucleoli, and that RNAi-mediated depletion of SmgGDS in cancer cells disrupts nucleolar morphology, signifying nucleolar stress. We show that nucleolar SmgGDS interacts with the RNA polymerase I transcription factor upstream binding factor (UBF). The RNAi-mediated depletion of UBF diminishes nucleolar localization of SmgGDS and promotes proteasome-mediated degradation of SmgGDS, indicating that nucleolar sequestration of SmgGDS by UBF stabilizes SmgGDS protein. The ability of SmgGDS to interact with UBF and localize in the nucleolus is diminished by expressing DiRas1 or DiRas2, which are small GTPases that bind SmgGDS and act as tumor suppressors. Taken together, our results support a novel nuclear role for SmgGDS in protecting malignant cells from nucleolar stress, thus promoting cell cycle progression and tumorigenesis.

C. elegans STK39/SPAK ortholog-mediated inhibition of ClC anion channel activity is regulated by WNK-independent ERK kinase signaling

PubMed Central

Falin, Rebecca A.; Miyazaki, Hiroaki

2011-01-01

Mammalian Ste20-like proline/alanine-rich kinase (SPAK) and oxidative stress-responsive 1 (OSR1) kinases phosphorylate and regulate cation-coupled Cl− cotransporter activity in response to cell volume changes. SPAK and OSR1 are activated via phosphorylation by upstream with-no-lysine (WNK) kinases. In Caenorhabditis elegans, the SPAK/OSR1 ortholog germinal center kinase (GCK)-3 binds to and regulates the activity of the cell volume- and meiotic cell cycle-dependent ClC anion channel CLH-3b. We tested the hypothesis that WNK kinases function in the GCK-3/CLH-3b signaling cascade. CLH-3b heterologously expressed in human embryonic kidney (HEK) cells was unaffected by coexpression with the single C. elegans WNK kinase, WNK-1, or kinase-dead WNK-1 dominant-negative mutants. RNA interference (RNAi) knockdown of the single Drosophila WNK kinase had no effect on the activity of CLH-3b expressed in Drosophila S2 cells. Similarly, RNAi silencing of C. elegans WNK-1 had no effect on basal or cell volume-sensitive activity of CLH-3b expressed endogenously in worm oocytes. Previous yeast 2-hybrid studies suggested that ERK kinases may function upstream of GCK-3. Pharmacological inhibition of ERK signaling disrupted CLH-3b activity in HEK cells in a GCK-3-dependent manner. RNAi silencing of the C. elegans ERK kinase MPK-1 or the ERK phosphorylating/activating kinase MEK-2 constitutively activated native CLH-3b. MEK-2 and MPK-1 play important roles in regulating the meiotic cell cycle in C. elegans oocytes. Cell cycle-dependent changes in MPK-1 correlate with the pattern of CLH-3b activation observed during oocyte meiotic maturation. We postulate that MEK-2/MPK-1 functions upstream from GCK-3 to regulate its activity during cell volume and meiotic cell cycle changes. PMID:21160027

The transcription factor Foxg1 regulates telencephalic progenitor proliferation cell autonomously, in part by controlling Pax6 expression levels

PubMed Central

2011-01-01

Background The transcription factor Foxg1 is an important regulator of telencephalic cell cycles. Its inactivation causes premature lengthening of telencephalic progenitor cell cycles and increased neurogenic divisions, leading to severe hypoplasia of the telencephalon. These proliferation defects could be a secondary consequence of the loss of Foxg1 caused by the abnormal expression of several morphogens (Fibroblast growth factor 8, bone morphogenetic proteins) in the telencephalon of Foxg1 null mutants. Here we investigated whether Foxg1 has a cell autonomous role in the regulation of telencephalic progenitor proliferation. We analysed Foxg1+/+↔Foxg1-/- chimeras, in which mutant telencephalic cells have the potential to interact with, and to have any cell non-autonomous defects rescued by, normal wild-type cells. Results Our analysis showed that the Foxg1-/- cells are under-represented in the chimeric telencephalon and the proportion of them in S-phase is significantly smaller than that of their wild-type neighbours, indicating that their under-representation is caused by a cell autonomous reduction in their proliferation. We then analysed the expression of the cell-cycle regulator Pax6 and found that it is cell-autonomously downregulated in Foxg1-/- dorsal telencephalic cells. We went on to show that the introduction into Foxg1-/- embryos of a transgene designed to reverse Pax6 expression defects resulted in a partial rescue of the telencephalic progenitor proliferation defects. Conclusions We conclude that Foxg1 exerts control over telencephalic progenitor proliferation by cell autonomous mechanisms that include the regulation of Pax6, which itself is known to regulate proliferation cell autonomously in a regional manner. PMID:21418559

DDX3X RNA helicase affects breast cancer cell cycle progression by regulating expression of KLF4.

PubMed

Cannizzaro, Ester; Bannister, Andrew John; Han, Namshik; Alendar, Andrej; Kouzarides, Tony

2018-05-21

DDX3X is a multifunctional RNA helicase with documented roles in different cancer types. Here, we demonstrate that DDX3X plays an oncogenic role in breast cancer cells by modulating the cell cycle. Depletion of DDX3X in MCF7 cells slows cell proliferation by inducing a G1 phase arrest. Notably, DDX3X inhibits expression of Kruppel-like factor 4 (KLF4), a transcription factor and cell cycle repressor. Moreover, DDX3X directly interacts with KLF4 mRNA and regulates its splicing. We show that DDX3X-mediated repression of KLF4 promotes expression of S-phase inducing genes in MCF7 breast cancer cells. These findings provide evidence for a novel function of DDX3X in regulating expression and downstream functions of KLF4, a master negative regulator of the cell cycle. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Circadian Clock Synchronization of the Cell Cycle in Zebrafish Occurs through a Gating Mechanism Rather Than a Period-phase Locking Process.

PubMed

Laranjeiro, Ricardo; Tamai, T Katherine; Letton, William; Hamilton, Noémie; Whitmore, David

2018-04-01

Studies from a number of model systems have shown that the circadian clock controls expression of key cell cycle checkpoints, thus providing permissive or inhibitory windows in which specific cell cycle events can occur. However, a major question remains: Is the clock actually regulating the cell cycle through such a gating mechanism or, alternatively, is there a coupling process that controls the speed of cell cycle progression? Using our light-responsive zebrafish cell lines, we address this issue directly by synchronizing the cell cycle in culture simply by changing the entraining light-dark (LD) cycle in the incubator without the need for pharmacological intervention. Our results show that the cell cycle rapidly reentrains to a shifted LD cycle within 36 h, with changes in p21 expression and subsequent S phase timing occurring within the first few hours of resetting. Reentrainment of mitosis appears to lag S phase resetting by 1 circadian cycle. The range of entrainment of the zebrafish clock to differing LD cycles is large, from 16 to 32 hour periods. We exploited this feature to explore cell cycle entrainment at both the population and single cell levels. At the population level, cell cycle length is shortened or lengthened under corresponding T-cycles, suggesting that a 1:1 coupling mechanism is capable of either speeding up or slowing down the cell cycle. However, analysis at the single cell level reveals that this, in fact, is not true and that a gating mechanism is the fundamental method of timed cell cycle regulation in zebrafish. Cell cycle length at the single cell level is virtually unaltered with varying T-cycles.

Circadian Clock Synchronization of the Cell Cycle in Zebrafish Occurs through a Gating Mechanism Rather Than a Period-phase Locking Process

PubMed Central

Tamai, T. Katherine; Letton, William; Hamilton, Noémie; Whitmore, David

2018-01-01

Studies from a number of model systems have shown that the circadian clock controls expression of key cell cycle checkpoints, thus providing permissive or inhibitory windows in which specific cell cycle events can occur. However, a major question remains: Is the clock actually regulating the cell cycle through such a gating mechanism or, alternatively, is there a coupling process that controls the speed of cell cycle progression? Using our light-responsive zebrafish cell lines, we address this issue directly by synchronizing the cell cycle in culture simply by changing the entraining light-dark (LD) cycle in the incubator without the need for pharmacological intervention. Our results show that the cell cycle rapidly reentrains to a shifted LD cycle within 36 h, with changes in p21 expression and subsequent S phase timing occurring within the first few hours of resetting. Reentrainment of mitosis appears to lag S phase resetting by 1 circadian cycle. The range of entrainment of the zebrafish clock to differing LD cycles is large, from 16 to 32 hour periods. We exploited this feature to explore cell cycle entrainment at both the population and single cell levels. At the population level, cell cycle length is shortened or lengthened under corresponding T-cycles, suggesting that a 1:1 coupling mechanism is capable of either speeding up or slowing down the cell cycle. However, analysis at the single cell level reveals that this, in fact, is not true and that a gating mechanism is the fundamental method of timed cell cycle regulation in zebrafish. Cell cycle length at the single cell level is virtually unaltered with varying T-cycles. PMID:29444612

Temporal remodeling of the cell cycle accompanies differentiation in the Drosophila germline.

PubMed

Hinnant, Taylor D; Alvarez, Arturo A; Ables, Elizabeth T

2017-09-01

Development of multicellular organisms relies upon the coordinated regulation of cellular differentiation and proliferation. Growing evidence suggests that some molecular regulatory pathways associated with the cell cycle machinery also dictate cell fate; however, it remains largely unclear how the cell cycle is remodeled in concert with cell differentiation. During Drosophila oogenesis, mature oocytes are created through a series of precisely controlled division and differentiation steps, originating from a single tissue-specific stem cell. Further, germline stem cells (GSCs) and their differentiating progeny remain in a predominantly linear arrangement as oogenesis proceeds. The ability to visualize the stepwise events of differentiation within the context of a single tissue make the Drosophila ovary an exceptional model for study of cell cycle remodeling. To describe how the cell cycle is remodeled in germ cells as they differentiate in situ, we used the Drosophila Fluorescence Ubiquitin-based Cell Cycle Indicator (Fly-FUCCI) system, in which degradable versions of GFP::E2f1 and RFP::CycB fluorescently label cells in each phase of the cell cycle. We found that the lengths of the G1, S, and G2 phases of the cell cycle change dramatically over the course of differentiation, and identified the 4/8-cell cyst as a key developmental transition state in which cells prepare for specialized cell cycles. Our data suggest that the transcriptional activator E2f1, which controls the transition from G1 to S phase, is a key regulator of mitotic divisions in the early germline. Our data support the model that E2f1 is necessary for proper GSC proliferation, self-renewal, and daughter cell development. In contrast, while E2f1 degradation by the Cullin 4 (Cul4)-containing ubiquitin E3 ligase (CRL4) is essential for developmental transitions in the early germline, our data do not support a role for E2f1 degradation as a mechanism to limit GSC proliferation or self-renewal. Taken together, these findings provide further insight into the regulation of cell proliferation and the acquisition of differentiated cell fate, with broad implications across developing tissues. Copyright © 2017 Elsevier Inc. All rights reserved.

Octyl gallate and gallic acid isolated from Terminalia bellarica regulates normal cell cycle in human breast cancer cell lines.

PubMed

Sales, Mary Selesty; Roy, Anita; Antony, Ludas; Banu, Sakhila K; Jeyaraman, Selvaraj; Manikkam, Rajalakshmi

2018-07-01

Herbal medicines stand unique and effective in treating human diseases. Terminalia bellarica (T. bellarica) is a potent medicinal herb, with a wide range of pharmacological activities. The present study was aimed to evaluate the effect of octyl gallate (OG) and gallic acid (GA) isolated from methanolic fruit extract of T. bellirica to inhibit the survival of breast cancer cells (MCF-7 & MDA-MB-231). Both OG & GA exhibited decreased MCF-7 & MDA-MB-231 survival and induced apoptosis, with IC 50 value of OG and GA as 40 μM and 80 μM respectively. No toxic effect was observed on normal breast cells (MCF-10A). The compounds inhibited cell cycle progression by altering the expression of the cell cycle regulators (Cyclin D1, D3, CDK-4, CDK-6, p18 INK4, p21Waf-1 and p27 KIP). Octyl gallate was more effective at low concentrations than GA. In-silico results provided stable interactions between the compounds and target proteins. The present investigation proved the downregulation of positive cell cycle regulators and upregulation of negative cell cycle regulators inducing apoptosis in compound-treated breast cancer cells. Hence, both the compounds may serve as potential anticancer agents and could be developed as breast cancer drugs, with further explorations. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

The Expression of Glyceraldehyde-3-Phosphate Dehydrogenase Associated Cell Cycle (GACC) Genes Correlates with Cancer Stage and Poor Survival in Patients with Solid Tumors

PubMed Central

Wang, Dunrui; Moothart, Daniel R.; Lowy, Douglas R.; Qian, Xiaolan

2013-01-01

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is often used as a stable housekeeping marker for constant gene expression. However, the transcriptional levels of GAPDH may be highly up-regulated in some cancers, including non-small cell lung cancers (NSCLC). Using a publically available microarray database, we identified a group of genes whose expression levels in some cancers are highly correlated with GAPDH up-regulation. The majority of the identified genes are cell cycle-dependent (GAPDH Associated Cell Cycle, or GACC). The up-regulation pattern of GAPDH positively associated genes in NSCLC is similar to that observed in cultured fibroblasts grown under conditions that induce anti-senescence. Data analysis demonstrated that up-regulated GAPDH levels are correlated with aberrant gene expression related to both glycolysis and gluconeogenesis pathways. Down-regulation of fructose-1,6-bisphosphatase (FBP1) in gluconeogenesis in conjunction with up-regulation of most glycolytic genes is closely related to high expression of GAPDH in the tumors. The data presented demonstrate that up-regulation of GAPDH positively associated genes is proportional to the malignant stage of various tumors and is associated with an unfavourable prognosis. Thus, this work suggests that GACC genes represent a potential new signature for cancer stage identification and disease prognosis. PMID:23620736

Regulation of Mih1/Cdc25 by protein phosphatase 2A and casein kinase 1

PubMed Central

Pal, Gayatri; Paraz, Maria T.Z.; Kellogg, Douglas R.

2008-01-01

The Cdc25 phosphatase promotes entry into mitosis by removing cyclin-dependent kinase 1 (Cdk1) inhibitory phosphorylation. Previous work suggested that Cdc25 is activated by Cdk1 in a positive feedback loop promoting entry into mitosis; however, it has remained unclear how the feedback loop is initiated. To learn more about the mechanisms that regulate entry into mitosis, we have characterized the function and regulation of Mih1, the budding yeast homologue of Cdc25. We found that Mih1 is hyperphosphorylated early in the cell cycle and is dephosphorylated as cells enter mitosis. Casein kinase 1 is responsible for most of the hyperphosphorylation of Mih1, whereas protein phosphatase 2A associated with Cdc55 dephosphorylates Mih1. Cdk1 appears to directly phosphorylate Mih1 and is required for initiation of Mih1 dephosphorylation as cells enter mitosis. Collectively, these observations suggest that Mih1 regulation is achieved by a balance of opposing kinase and phosphatase activities. Because casein kinase 1 is associated with sites of polar growth, it may regulate Mih1 as part of a signaling mechanism that links successful completion of growth-related events to cell cycle progression. PMID:18316413

75 FR 65558 - Final Supplemental Environmental Impact Statement, Single Nuclear Unit at the Bellefonte Plant...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-25

... TENNESSEE VALLEY AUTHORITY Final Supplemental Environmental Impact Statement, Single Nuclear Unit... Environmental Impact Statement for a Single Nuclear Unit at the Bellefonte Plant Site (final SEIS) on September... the ROD. TVA prepared the final SEIS to update the extensive environmental information and analyses...

Improving Teaching Effectiveness through the Application of SPC Methodology

ERIC Educational Resources Information Center

Cadden, David; Driscoll, Vincent; Thompson, Mark

2008-01-01

One method used extensively to aid in determining instruction effectiveness is Student Evaluations of Instruction (SEI). This paper examines the use of statistical Process Control charts as a way to correctly measure teaching effectiveness. This field studying SEIs has produced a significant literature. It is not surprising that there is…

75 FR 16731 - Young Dodge SEIS; Kootenai National Forest, Lincoln County, MT

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-02

... (SEIS) for the Young Dodge project. The Young Dodge project includes urban interface fuels treatments... management changes, including road decommissioning. The project is located in the Young Dodge planning... Wildland-Urban Interface, to decrease the likelihood that fires would become stand-replacing wildfires; (2...

Transcriptional response of skeletal muscle to a low-protein gestation diet in porcine offspring accumulates in growth- and cell cycle-regulating pathways.

PubMed

Oster, Michael; Murani, Eduard; Metges, Cornelia C; Ponsuksili, Siriluck; Wimmers, Klaus

2012-08-17

Inadequate maternal protein supply during gestation represents an environmental factor that affects physiological signaling pathways with long-term consequences for growth, function, and structure of various tissues. Hypothesizing that the offspring's transcriptome is persistently altered by maternal diets, we used a porcine model to monitor the longitudinal expression changes in muscle to identify pathways relevant to fetal initiation of postnatal growth and development. German Landrace gilts were fed isoenergetic gestational diets containing 6.5% (LP) or 12.1% protein. The longissimus dorsi samples were collected from offspring at 94 days postconception (dpc) and 1, 28, and 188 days postnatum (dpn) for expression profiling. At 94 dpc, 1 dpn, and 28 dpn relatively few transcripts (<130) showed an altered abundance between the dietary groups. In fact, at 94 dpc genes of G2/M checkpoint regulation and mitotic roles of Polo-like kinases showed lowered transcript abundance in LP. At 188 dpn 677 transcripts were altered including those related to oxidative phosphorylation, citrate cycle, fatty acid metabolism (higher abundance in LP) and cell cycle regulation (lower abundance in LP). Correspondingly, transcriptional alterations during pre and postnatal development differed considerably among dietary groups, particularly for genes related to cell cycle regulation (G1/S and G2/M checkpoint regulation; cyclines), growth factor signaling (GH, IGF1, mTOR, RAN, VEGF, INSR), lipid metabolism, energy metabolism, and nucleic acid metabolism. In skeletal muscle, fetal programming related to maternal LP diets disturbed gene expression in growth-related pathways into adulthood. Diet-dependent gene expression may hamper proper development, thereby affecting signaling pathways related to energy utilization.

Soft X-ray emission spectroscopy of liquids and lithium batterymaterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Augustsson, Andreas

2004-01-01

Lithium ion insertion into electrode materials is commonly used in rechargeable battery technology. The insertion implies changes in both the crystal structure and the electronic structure of the electrode material. Side-reactions may occur on the surface of the electrode which is exposed to the electrolyte and form a solid electrolyte interface (SEI). The understanding of these processes is of great importance for improving battery performance. The chemical and physical properties of water and alcohols are complicated by the presence of strong hydrogen bonding. Various experimental techniques have been used to study geometrical structures and different models have been proposed tomore » view the details of how these liquids are geometrically organized by hydrogen bonding. However, very little is known about the electronic structure of these liquids, mainly due to the lack of suitable experimental tools. In this thesis examples of studies of lithium battery electrodes and liquid systems using soft x-ray emission spectroscopy will be presented. Monochromatized synchrotron radiation has been used to accomplish selective excitation, in terms of energy and polarization. The electronic structure of graphite electrodes has been studied, before and after lithium intercalation. Changes in the electronic structure upon lithiation due to transfer of electrons into the graphite π-bands have been observed. Transfer of electrons in to the 3d states of transition metal oxides upon lithiation have been studied, through low energy excitations as dd- and charge transfer-excitations. A SEI was detected on cycled graphite electrodes. By the use of selective excitation different carbon sites were probed in the SEI. The local electronic structure of water, methanol and mixtures of the two have been examined using a special liquid cell, to separate the liquid from the vacuum in the experimental chamber. Results from the study of liquid water showed a strong influence on the 3a1 molecular orbital and orbital mixing between water molecules upon hydrogen bonding. Apart from the four-hydrogen-bonding structure in water, a structure where one hydrogen bond is broken could be separated and identified. The soft x-ray emission study of methanol showed the existence of ring and chain formations in the liquid phase and the dominating structures are formed of 6 and 8 molecules. Upon mixing of the two liquids, a segregation at the molecular level was found and the formation of new structures, which could explain the unexpected low increase of the entropy.« less

Protein PSMD8 may mediate microgravity-induced cell cycle arrest

NASA Astrophysics Data System (ADS)

Hang, Xiaoming; Sun, Yeqing; Xu, Dan; Wu, Di; Chen, Xiaoning

Microgravity environment of space can induce a serial of changes in cells, such as morphology alterations, cytoskeleton disorder and cell cycle disturbance. Our previous study of simulated-microgravity on zebrafish (Danio rerio) embryos demonstrated 26s proteasome non-ATPase regulatory subunit 8 (PSMD8) might be a microgravity sensitive gene. However, functional study on PSMD8 is very limited and it has not been cloned in zebrafish till now. In this study, we tried to clone PSMD8 gene in zebrafish, quantify its protein expression level in zebrafish embryos after simulated microgravity and identify its possible function in cell cycle regulation. A rotary cell culture system (RCCS) designed by national aeronautics and apace administration (NASA) of America was used to simulate microgravity. The full-length of psmd8 gene in zebrafish was cloned. Preliminary analysis on its sequence and phylogenetic tree construction were carried out subsequently. Quantitative analysis by western blot showed that PSMD8 protein expression levels were significantly increased 1.18 and 1.22 times after 24-48hpf and 24-72hpf simulated microgravity, respectively. Moreover, a significant delay on zebrafish embryo development was found in simulated-microgravity exposed group. Inhibition of PSMD8 protein in zebrafish embryonic cell lines ZF4 could block cell cycle in G1 phase, which indicated that PSMD8 may play a role in cell cycle regulation. Interestingly, simulated-microgravity could also block ZF4 cell in G1 phase. Whether it is PSMD8 mediated cell cycle regulation result in the zebrafish embryo development delay after simulated microgravity exposure still needs further study. Key Words: PSMD8; Simulated-microgravity; Cell cycle; ZF4 cell line

Regulation of FOXO1-mediated transcription and cell proliferation by PARP-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sakamaki, Jun-ichi; Daitoku, Hiroaki; Yoshimochi, Kenji

2009-05-08

Forkhead box O (FOXO) transcription factors play an important role in a wide range of biological processes, including cell cycle control, apoptosis, detoxification of reactive oxygen species, and gluconeogenesis through regulation of gene expression. In this study, we demonstrated that PARP-1 functions as a negative regulator of FOXO1. We showed that PARP-1 directly binds to and poly(ADP-ribosyl)ates FOXO1 protein. PARP-1 represses FOXO1-mediated expression of cell cycle inhibitor p27{sup Kip1} gene. Notably, poly(ADP-ribosyl)ation activity was not required for the repressive effect of PARP-1 on FOXO1 function. Furthermore, knockdown of PARP-1 led to a decrease in cell proliferation in a manner dependentmore » on FOXO1 function. Chromatin immunoprecipitation experiments confirmed that PARP-1 is recruited to the p27{sup Kip1} gene promoter through a binding to FOXO1. These results suggest that PARP-1 acts as a corepressor for FOXO1, which could play an important role in proper cell proliferation by regulating p27{sup Kip1} gene expression.« less

SeisCube Instrument and Environment Considerations for the Didymos System Geophysical Exploration

NASA Astrophysics Data System (ADS)

Cadu, Alexandre; Murdoch, Naomi; Mimoun, David; Karatekin, Ozgur; Garica, Raphaël F.; Carrasco, Jose A.; De Quiros, Francisco G.; Vasseur, Hugues; Eubanks, Marshall; Radley, Charles; Ritter, Birgit; Dehant, Veronique

2016-04-01

In the context of the Asteroid Impact & Deviation Assessment (AIDA) mission proposed by ESA and NASA, the Asteroid Geophysical Explorer (AGEX) mission concept has been selected for a preliminary study phase. Two 3-Unit CubeSats are embedded into the AIM probe and released into the asteroid binary system [1]. SeisCube will be deployed close to the secondary to reach its surface at a low relative velocity in order to stay on the ground after several rebounds, in a similar way that is foreseen for Mascot-2. The purpose of SeisCube is to provide information about the surface, the sub-surface and the internal structure of the asteroid, by analyzing rebound acceleration profile and seismic activity [2]. We describe the considered instrumentation necessary to fulfill the science objectives (gravimeters, accelerometers, geophones, etc.) in terms of measurement dynamics, frequency ranges, acquisition methods and other common budgets for space equipment. We also present the environment considerations which have to be taken into account for the platform and payload designs. The thermal aspect will be particularly discussed since it is a major issue in the airless body exploration [3] [4]. It implies some modifications in the CubeSat structure, integration and thermal regulation to ensure survival and operations under extreme conditions at the asteroid surface. We then describe the platform subsystems needed to ensure the operations after the deployment and the associated budgets and accommodation. As a direct consequence of the previous topics, we will finally discuss the possible trades-off to satisfy the main science requirements and the associated concept of operations. [1] O. Karatekin, D. Mimoun, J. A. Carrasco, N. Murdoch, A. Cadu, R. F. Garcia, F. G. De Quiros, H. Vasseur, B. Ritter, M. Eubanks, C. Radley and V. Dehant, "The Asteroid Geophysical Explorer (AGEX): Proposal to explore Didymos system using Cubsats," in European Geophysical Union, 2016. [2] N. Murdoch, A. Cadu, D. Mimoun, O. Karatekin, R. F. Garcia, J. A. Carrasco, F. G. De Guiros, H. Vasseur, B. Ritter, M. Eubanks, C. Radley and V. Dehart, "Invertigating the surface and subsurface properties of the Didymos binary asteroid with a landed CubeSat," in European Geophysical Union, 2016. [3] J. De Lafontaine and D. Kassing, "Technologies and Concepts for Lunar Surface Exploration," Acta Astronautica, vol. 38, no. 2, pp. 125-129, 1996. [4] S. Ulamec, J. Biele and E. Trollope, "How to survive a Lunar night," Planetary and Space Science, vol. 58, no. 14-15, pp. 1985-1995, 2010.

24 CFR 3285.4 - Incorporation by reference (IBR).

Code of Federal Regulations, 2012 CFR

2012-04-01

...-6600, fax number (253) 565-7265. (1) PS1-95, Construction and Industrial Plywood (with typical APA... for Engineering Purposes (Unified Soil Classification System), 2000, IBR approved for the table at... purchase from the Structural Engineering Institute/American Society of Civil Engineers (SEI/ASCE), 1801...

24 CFR 3285.4 - Incorporation by reference (IBR).

Code of Federal Regulations, 2011 CFR

2011-04-01

...-6600, fax number (253) 565-7265. (1) PS1-95, Construction and Industrial Plywood (with typical APA... for Engineering Purposes (Unified Soil Classification System), 2000, IBR approved for the table at... purchase from the Structural Engineering Institute/American Society of Civil Engineers (SEI/ASCE), 1801...

Interacting TCP and NLP transcription factors control plant responses to nitrate availability.

PubMed

Guan, Peizhu; Ripoll, Juan-José; Wang, Renhou; Vuong, Lam; Bailey-Steinitz, Lindsay J; Ye, Dening; Crawford, Nigel M

2017-02-28

Plants have evolved adaptive strategies that involve transcriptional networks to cope with and survive environmental challenges. Key transcriptional regulators that mediate responses to environmental fluctuations in nitrate have been identified; however, little is known about how these regulators interact to orchestrate nitrogen (N) responses and cell-cycle regulation. Here we report that teosinte branched1/cycloidea/proliferating cell factor1-20 (TCP20) and NIN-like protein (NLP) transcription factors NLP6 and NLP7, which act as activators of nitrate assimilatory genes, bind to adjacent sites in the upstream promoter region of the nitrate reductase gene, NIA1 , and physically interact under continuous nitrate and N-starvation conditions. Regions of these proteins necessary for these interactions were found to include the type I/II Phox and Bem1p (PB1) domains of NLP6&7, a protein-interaction module conserved in animals for nutrient signaling, and the histidine- and glutamine-rich domain of TCP20, which is conserved across plant species. Under N starvation, TCP20-NLP6&7 heterodimers accumulate in the nucleus, and this coincides with TCP20 and NLP6&7-dependent up-regulation of nitrate assimilation and signaling genes and down-regulation of the G 2 /M cell-cycle marker gene, CYCB1;1 TCP20 and NLP6&7 also support root meristem growth under N starvation. These findings provide insights into how plants coordinate responses to nitrate availability, linking nitrate assimilation and signaling with cell-cycle progression.

The Anaphase-Promoting Complex is a dual integrator that regulates both microRNA-mediated transcriptional regulation of Cyclin B1 and degradation of Cyclin B1 during Arabidopsis male gametophyte development

USDA-ARS?s Scientific Manuscript database

The anaphase-promoting complex/cyclosome (APC/C), an essential ubiquitin protein ligase, regulates mitotic progression and exit by enhancing degradation of cell cycle regulatory proteins, such as CYCB1;1, whose transcripts are upregulated by DUO POLLEN1 (DUO1). DUO1 is required for cell division in ...

The Anaphase-Promoting Complex Is a Dual Integrator That Regulates Both MicroRNA-Mediated Transcriptional Regulation of Cyclin B1 and Degradation of Cyclin B1 during Arabidopsis Male Gametophyte Development

USDA-ARS?s Scientific Manuscript database

The anaphase-promoting complex/cyclosome (APC/C), an essential ubiquitin protein ligase, regulates mitotic progression and exit by enhancing degradation of cell cycle regulatory proteins, such as CYCB1;1, whose transcripts are upregulated by DUO POLLEN1 (DUO1). DUO1 is required for cell division in ...

Molecular Genetic Traits Influencing Maize Endosperm Development and Value: Closeout Report for DOE Grant DE-FG02-96ER20242

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brian A. Larkins

2012-09-12

Development of the endosperm in cereal grasses entails different phases characterized by cell division, endoreduplication, accumulation of storage metabolites and cell death, which need to be carried out in an orderly fashion. While correct regulation of the cell cycle plays an essential role in endosperm development, the key regulatory factors and how the cell cycle interfaces with other pathways in this developmental context are largely unknown. We investigated the cyclin-dependent kinase (CDK)-retinoblastoma pathway and how it controls the cell cycle and coordinates it with other processes during maize endosperm development. Retinoblastoma-related (RBR) proteins may be inactivated through CDK-mediated phosphorylation, butmore » the identity of the responsible kinase in maize is unknown. We have previously shown that down-regulation of CDKA;1 severely inhibits the endoreduplication cell cycle and suggested that CDK may be an up-stream regulator of the retinoblastoma pathway. We discovered two types of maize RBR genes, RBR1 and RBR3, which differ in terms of structure, regulation and function. Phylogenetic analyses indicate that these genes may be distinctive features of the Poaceae. We found that RBR3 plays a positive rather than a negative role in DNA replication, cell transformation, and the expression of the minichromosome maintenance (MCM)2-7 family of DNA replication factors. These features are a paradigm shift in RBR gene function and appear to be unique within the RBR gene family. They suggest the existence in maize and related cereal crops of specific RBR/E2F-dependent pathways impinging on the cell cycle and development. RBR1 was down-regulated in transgenic endosperm using RNAi approaches. This resulted in the de-repression of a number of down-stream E2F targets, including RBR3, the MCM2-7 gene family, DNA methyltransferase (MET)1, CDKB;1, and the recently identified RBR4 gene. It also increased endosperm ploidy levels, stimulated the production of a larger number of cells, reduced the average cell size, and promoted programmed cell death. To test whether CDKA;1 inhibits RBR1 (through phosphorylation) in the pathway that leads to DNA synthesis and endoreduplication, the two CDKA;1 and RBR1 down-regulated mutants were crossed and their progeny analyzed. Our results indicate that CDKA;1 controls endoreduplication through an RBR1-dependent pathway. However, the ability of RBR1 to repress gene expression programs is independent from CDKA1, suggesting the presence of two differently regulated RBR1 activities in developing endosperm. One type of RBR1 activity controls E2F-dependent gene expression and is largely independent from CDKA;1, while another suppresses endoreduplication and can be inhibited by CDKA;1. In addition, RBR1 is part of a regulatory feedback loop that impinges on CDK activity. Together, these results indicate that the CDKA;1-RBR1 pathway integrates and controls different processes associated with endosperm development. Genome-wide analyses of the transcriptome, metabolome, and epigenetic mechanisms to understand how the cell cycle is coordinated with other pathways at a systems biology level are currently underway.« less

Fluorinated Phosphazene Co-solvents for Improved Thermal and Safety Performance in Lithium-Ion Battery Electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harry W. Rollins; Mason K. Harrup; Eric J. Dufek

2014-10-01

The safety of lithium-ion batteries is coming under increased scrutiny as they are being adopted for large format applications especially in the vehicle transportation industry and for grid-scale energy storage. The primary short-comings of lithium-ion batteries are the flammability of the liquid electrolyte and sensitivity to high voltage and elevated temperatures. We have synthesized a series of non-flammable fluorinated phosphazene liquids and blended them with conventional carbonate solvents. While the use of these phosphazenes as standalone electrolytes is highly desirable, they simply do not satisfy all of the many requirements that must be met such as high LiPF6 solubility andmore » low viscosity, thus we have used them as additives and co-solvents in blends with typical carbonates. The physical and electrochemical properties of the electrolyte blends were characterized, and then the blends were used to build 2032-type coin cells which were evaluated at constant current cycling rates from C/10 to C/1. We have evaluated the performance of the electrolytes by determining the conductivity, viscosity, flash point, vapor pressure, thermal stability, electrochemical window, cell cycling data, and the ability to form solid electrolyte interphase (SEI) films. This paper presents our results on a series of chemically similar fluorinated cyclic phosphazene trimers, the FM series, which has exhibited numerous beneficial effects on battery performance, lifetimes, and safety aspects.« less

Cell cycle-dependent regulation of Greatwall kinase by protein phosphatase 1 and regulatory subunit 3B.

PubMed

Ren, Dapeng; Fisher, Laura A; Zhao, Jing; Wang, Ling; Williams, Byron C; Goldberg, Michael L; Peng, Aimin

2017-06-16

Greatwall (Gwl) kinase plays an essential role in the regulation of mitotic entry and progression. Mitotic activation of Gwl requires both cyclin-dependent kinase 1 (CDK1)-dependent phosphorylation and its autophosphorylation at an evolutionarily conserved serine residue near the carboxyl terminus (Ser-883 in Xenopus ). In this study we show that Gwl associates with protein phosphatase 1 (PP1), particularly PP1γ, which mediates the dephosphorylation of Gwl Ser-883. Consistent with the mitotic activation of Gwl, its association with PP1 is disrupted in mitotic cells and egg extracts. During mitotic exit, PP1-dependent dephosphorylation of Gwl Ser-883 occurs prior to dephosphorylation of other mitotic substrates; replacing endogenous Gwl with a phosphomimetic S883E mutant blocks mitotic exit. Moreover, we identified PP1 regulatory subunit 3B (PPP1R3B) as a targeting subunit that can direct PP1 activity toward Gwl. PPP1R3B bridges PP1 and Gwl association and promotes Gwl Ser-883 dephosphorylation. Consistent with the cell cycle-dependent association of Gwl and PP1, Gwl and PPP1R3B dissociate in M phase. Interestingly, up-regulation of PPP1R3B facilitates mitotic exit and blocks mitotic entry. Thus, our study suggests PPP1R3B as a new cell cycle regulator that functions by governing Gwl dephosphorylation. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

A map of protein dynamics during cell-cycle progression and cell-cycle exit

PubMed Central

Gookin, Sara; Min, Mingwei; Phadke, Harsha; Chung, Mingyu; Moser, Justin; Miller, Iain; Carter, Dylan

2017-01-01

The cell-cycle field has identified the core regulators that drive the cell cycle, but we do not have a clear map of the dynamics of these regulators during cell-cycle progression versus cell-cycle exit. Here we use single-cell time-lapse microscopy of Cyclin-Dependent Kinase 2 (CDK2) activity followed by endpoint immunofluorescence and computational cell synchronization to determine the temporal dynamics of key cell-cycle proteins in asynchronously cycling human cells. We identify several unexpected patterns for core cell-cycle proteins in actively proliferating (CDK2-increasing) versus spontaneously quiescent (CDK2-low) cells, including Cyclin D1, the levels of which we find to be higher in spontaneously quiescent versus proliferating cells. We also identify proteins with concentrations that steadily increase or decrease the longer cells are in quiescence, suggesting the existence of a continuum of quiescence depths. Our single-cell measurements thus provide a rich resource for the field by characterizing protein dynamics during proliferation versus quiescence. PMID:28892491

Cell cycle effects of L-sulforaphane, a major antioxidant from cruciferous vegetables: The role of the anaphase promoting complex.

PubMed

Shelley, Zhaoping; Royce, Simon G; Ververis, Katherine; Karagiannis, Tom C

2014-01-01

L-sulforaphane (LSF) is a natural isothiocyanate found in cruciferous vegetables particularly broccoli. LSF has been identified as a potent antioxidant and anti-cancer agent and is widely known to regulate phase II detoxifying enzymes and induce cell cycle arrest or apoptosis in malignant cells in vitro and in vivo. Previous studies have found significant G2/M cell cycle arrest in response to LSF in various model of cancer and results have mainly been attributed to increased cyclin B1 protein levels and increased p21expression. Using genome-wide mRNA-Seq analysis we provide insights into the molecular mechanisms of action of LSF to identify a key pathway in cell cycle progression - the role of the anaphase promoting complex (APC) pathway. We evaluated gene expression changes in human erythroleukemic K562 cells following treatment with 15 μM LSF for 48h and compared them to immortalized human keratinocytes, human microvascular endothelial cells (HMEC-1) cells and normal human umbilical endothelial cells (HUVEC). We identified disparate gene expression changes in response to LSF between malignant and normal cells and immortalized cell lines. The results highlight significant down-regulation of kinase CDK1 which is suggestive that the existence and activity of APC/CDC20 complex will be inhibited along with its associated down-stream degradation of key cell cycle regulators preventing cell cycle progression from mitotic exit.

pRb phosphorylation regulates the proliferation of supporting cells in gentamicin-damaged neonatal avian utricle.

PubMed

Wu, Jingfang; Sun, Shan; Li, Wenyan; Chen, Yan; Li, Huawei

2014-10-01

The ability of nonmammalian vertebrates to regenerate hair cells (HCs) after damage-induced HC loss has stimulated and inspired research in the field of HC regeneration. The protein pRb encoded by retinoblastoma gene Rb1 forces sensory progenitor cells to exit cell cycle and maintain differentiated HCs and supporting cells (SCs) in a quiescent state. pRb function is regulated by phosphorylation through the MEK/ERK or the pRb/Raf-1 signaling pathway. In our previous study, we have shown that pRb phosphorylation is crucial for progenitor cell proliferation and survival during the early embryonic stage of avian otocyst sensory epithelium development. However, in damaged avian utricle, the role of pRb in regulating the cell cycling of SCs or HCs regeneration still remains unclear. To further elucidate the function of pRb phosphorylation on SCs re-entering the cell cycle triggered by gentamycin-induced HCs damage, we isolated neonatal chicken utricles and treated them with the MEK inhibitor U0126 or the pRb/Raf-1 inhibitor RRD-251, respectively in vitro. We found that after gentamycin-induced HCs damage, pRb phosphorylation is important for the quiescent SCs re-entering the cell cycle in the neonatal chicken utricle. In addition, the proliferation of SCs decreased in a dose-dependent manner in response to both U0126 and RRD-251, which indicates that both the MEK/ERK and the pRb/Raf-1 signaling pathway play important roles in pRb phosphorylation in damaged neonatal chicken utricle. Together, these findings on the function of pRb in damaged neonatal chicken utricle improve our understanding of the regulation of the cell cycle of SCs after HCs loss and may shed light on the mammalian HC regeneration from SCs in damaged organs.

Knockdown of human deubiquitinase PSMD14 induces cell cycle arrest and senescence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byrne, Ann; McLaren, Rajashree P.; Mason, Paul

2010-01-15

The PSMD14 (POH1, also known as Rpn11/MPR1/S13/CepP1) protein within the 19S complex (19S cap; PA700) is responsible for substrate deubiquitination during proteasomal degradation. The role of PSMD14 in cell proliferation and senescence was explored using siRNA knockdown in carcinoma cell lines. Our results reveal that down-regulation of PSMD14 by siRNA transfection had a considerable impact on cell viability causing cell arrest in the G0-G1 phase, ultimately leading to senescence. The molecular events associated with decreased cell proliferation, cell cycle arrest and senescence include down-regulation of cyclin B1-CDK1-CDC25C, down-regulation of cyclin D1 and up-regulation of p21{sup /Cip} and p27{sup /Kip1}. Mostmore » notably, phosphorylation of the retinoblastoma protein was markedly reduced in PSMD14 knockdown cells. A comparative study with PSMB5, a subunit of the 20S proteasome, revealed that PSMB5 and PSMD14 have different effects on cell cycle, senescence and associated molecular events. These data support the view that the 19S and 20S subunits of the proteasome have distinct biological functions and imply that targeting 19S and 20S would have distinct molecular consequences on tumor cells.« less

SEI power source alternatives for rovers and other multi-kWe distributed surface applications

NASA Technical Reports Server (NTRS)

Bents, David J.; Kohout, L. L.; Mckissock, Barbara I.; Rodriguez, C. D.; Withrow, C. A.; Colozza, A.; Hanlon, James C.; Schmitz, Paul C.

1991-01-01

To support the Space Exploration Initiative (SEI), a study was performed to investigate power system alternatives for the rover vehicles and servicers that were subsequently generated for each of these rovers and servicers, candidate power sources incorporating various power generation and energy storage technologies were identified. The technologies were those believed most appropriate to the SEI missions, and included solar, electrochemical, and isotope systems. The candidates were characterized with respect to system mass, deployed area, and volume. For each of the missions a preliminary selection was made. Results of this study depict the available power sources in light of mission requirements as they are currently defined.

Bombyx mori cyclin-dependent kinase inhibitor is involved in regulation of the silkworm cell cycle.

PubMed

Tang, X-F; Zhou, X-L; Zhang, Q; Chen, P; Lu, C; Pan, M-H

2018-06-01

Cyclin-dependent kinase inhibitors (CKIs) are negative regulators of the cell cycle. They can bind to cyclin-dependent kinase (CDK)-cyclin complexes and inhibit CDK activities. We identified a single homologous gene of the CDK interacting protein/kinase inhibitory protein (Cip/Kip) family, BmCKI, in the silkworm, Bombyx mori. The gene transcribes two splice variants: a 654-bp-long BmCKI-L (the longer splice variant) encoding a protein with 217 amino acids and a 579-bp-long BmCKI-S (the shorter splice variant) encoding a protein with 192 amino acids. BmCKI-L and BmCKI-S contain the Cip/Kip family conserved cyclin-binding domain and the CDK-binding domain. They are localized in the nucleus and have an unconventional bipartite nuclear localization signal at amino acid residues 181-210. Overexpression of BmCKI-L or BmCKI-S affected cell cycle progression; the cell cycle was arrested in the first gap phase of cell cycle (G1). RNA interference of BmCKI-L or BmCKI-S led to cells accumulating in the second gap phase and the mitotic phase of cell cycle (G2/M). Both BmCKI-L and BmCKI-S are involved in cell cycle regulation and probably have similar effects. The transgenic silkworm with BmCKI-L overexpression (BmCKI-L-OE), exhibited embryonic lethal, larva developmental retardation and lethal phenotypes. These results suggest that BmCKI-L might regulate the growth and development of silkworm. These findings clarify the function of CKIs and increase our understanding of cell cycle regulation in the silkworm. © 2018 The Royal Entomological Society.

c-Myc plays a key role in TADs-induced apoptosis and cell cycle arrest in human hepatocellular carcinoma cells.

PubMed

Zhang, Dongdong; Qi, Junpeng; Liu, Rui; Dai, Bingling; Ma, Weina; Zhan, Yingzhuan; Zhang, Yanmin

2015-01-01

Cancer cell growth is complicated progression which is regulated and controlled by multiple factors including cell cycle, migration and apoptosis. In present study, we report that TADs, a novel derivative of taspine, has an essential role in resisting hepatocellular carcinoma growth (including arrest cell cycle) and migration, and inducing cell apoptosis. Our findings demonstrated that the TADs showed good inhibition on the hepatoma cell growth and migration, and good action on apoptosis induction. Using genome-wide microarray analysis, we found the down-regulated growth and apoptosis factors, and selected down-regulated genes were confirmed by Western blot. Knockdown of a checkpoint c-Myc by siRNA significantly attenuated tumor inhibition and apoptosis effects of TADs. Moreover, our results indicated TADs could simultaneously increase cyclin D1 protein levels and decrease amount of cyclin E, cyclin B1 and cdc2 of the cycle proteins, and also TADs reduced Bcl-2 expression, and upregulated Bad, Bak and Bax activities. In conclusion, these results illustrated that TADs is a key factor in growth and apoptosis signaling inhibitor, has potential in cancer therapy.

Morphogenesis checkpoint kinase Swe1 is the executor of lipolysis-dependent cell-cycle progression

PubMed Central

Chauhan, Neha; Visram, Myriam; Cristobal-Sarramian, Alvaro; Sarkleti, Florian

2015-01-01

Cell growth and division requires the precise duplication of cellular DNA content but also of membranes and organelles. Knowledge about the cell-cycle–dependent regulation of membrane and storage lipid homeostasis is only rudimentary. Previous work from our laboratory has shown that the breakdown of triacylglycerols (TGs) is regulated in a cell-cycle–dependent manner, by activation of the Tgl4 lipase by the major cyclin-dependent kinase Cdc28. The lipases Tgl3 and Tgl4 are required for efficient cell-cycle progression during the G1/S (Gap1/replication phase) transition, at the onset of bud formation, and their absence leads to a cell-cycle delay. We now show that defective lipolysis activates the Swe1 morphogenesis checkpoint kinase that halts cell-cycle progression by phosphorylation of Cdc28 at tyrosine residue 19. Saturated long-chain fatty acids and phytosphingosine supplementation rescue the cell-cycle delay in the Tgl3/Tgl4 lipase-deficient strain, suggesting that Swe1 activity responds to imbalanced sphingolipid metabolism, in the absence of TG degradation. We propose a model by which TG-derived sphingolipids are required to activate the protein phosphatase 2A (PP2ACdc55) to attenuate Swe1 phosphorylation and its inhibitory effect on Cdc28 at the G1/S transition of the cell cycle. PMID:25713391

Cyclin-dependent kinase inhibitor p21(Waf1): contemporary view on its role in senescence and oncogenesis.

PubMed

Romanov, V S; Pospelov, V A; Pospelova, T V

2012-06-01

p21(Waf1) was identified as a protein suppressing cyclin E/A-CDK2 activity and was originally considered as a negative regulator of the cell cycle and a tumor suppressor. It is now considered that p21(Waf1) has alternative functions, and the view of its role in cellular processes has begun to change. At present, p21(Waf1) is known to be involved in regulation of fundamental cellular programs: cell proliferation, differentiation, migration, senescence, and apoptosis. In fact, it not only exhibits antioncogenic, but also oncogenic properties. This review provides a contemporary understanding of the functions of p21(Waf1) depending on its intracellular localization. On one hand, when in the nucleus, it serves as a negative cell cycle regulator and tumor suppressor, in particular by participating in the launch of a senescence program. On the other hand, when p21(Waf1) is localized in the cytoplasm, it acts as an oncogene by regulating migration, apoptosis, and proliferation.

Cell cycle accumulation of the proliferating cell nuclear antigen PCN-1 transitions from continuous in the adult germline to intermittent in the early embryo of C. elegans.

PubMed

Kocsisova, Zuzana; Kornfeld, Kerry; Schedl, Tim

2018-05-30

The proliferating cell nuclear antigen (PCNA or PCN-1 in C. elegans), an essential processivity factor for DNA polymerase δ, has been widely used as a marker of S-phase. In C. elegans early embryos, PCN-1 accumulation is cyclic, localizing to the nucleus during S-phase and the cytoplasm during the rest of the cell cycle. The C. elegans larval and adult germline is an important model systems for studying cell cycle regulation, and it was observed that the cell cycle regulator cyclin E (CYE-1 in C. elegans) displays a non-cyclic, continuous accumulation pattern in this tissue. The accumulation pattern of PCN-1 has not been well defined in the larval and adult germline, and the objective of this study was to determine if the accumulation pattern is cyclic, as in other cells and organisms, or continuous, similar to cyclin E. To study the larval and adult germline accumulation of PCN-1 expressed from its native locus, we used CRISPR/Cas9 technology to engineer a novel allele of pcn-1 that encodes an epitope-tagged protein. S-phase nuclei were labeled using EdU nucleotide incorporation, and FLAG::PCN-1 was detected by antibody staining. All progenitor zone nuclei, including those that were not in S-phase (as they were negative for EdU staining) showed PCN-1 accumulation, indicating that PCN-1 accumulated during all cell cycle phases in the germline progenitor zone. The same result was observed with a GFP::PCN-1 fusion protein expressed from a transgene. pcn-1 loss-of-function mutations were analyzed, and pcn-1 was necessary for robust fertility and embryonic development. In the C. elegans early embryo as well as other organisms, PCN-1 accumulates in nuclei only during S-phase. By contrast, in the progenitor zone of the germline of C. elegans, PCN-1 accumulated in nuclei during all cell cycle stages. This pattern is similar to accumulation pattern of cyclin E. These observations support the model that mitotic cell cycle regulation in the germline stem and progenitor cells is distinct from somatic cells, as it does not heavily rely on cyclic accumulation of classic cell cycle proteins.

Degradation of the human mitotic checkpoint kinase Mps1 is cell cycle-regulated by APC-cCdc20 and APC-cCdh1 ubiquitin ligases.

PubMed

Cui, Yongping; Cheng, Xiaolong; Zhang, Ce; Zhang, Yanyan; Li, Shujing; Wang, Chuangui; Guadagno, Thomas M

2010-10-22

Mps1 is a dual specificity protein kinase with key roles in regulating the spindle assembly checkpoint and chromosome-microtubule attachments. Consistent with these mitotic functions, Mps1 protein levels fluctuate during the cell cycle, peaking at early mitosis and abruptly declining during mitotic exit and progression into the G(1) phase. Although evidence in budding yeast indicates that Mps1 is targeted for degradation at anaphase by the anaphase-promoting complex (APC)-c(Cdc20) complex, little is known about the regulatory mechanisms that govern Mps1 protein levels in human cells. Here, we provide evidence for the ubiquitin ligase/proteosome pathway in regulating human Mps1 levels during late mitosis through G(1) phase. First, we showed that treatment of HEK 293T cells with the proteosome inhibitor MG132 resulted in an increase in both the polyubiquitination and the accumulation of Mps1 protein levels. Next, Mps1 was shown to co-precipitate with APC and its activators Cdc20 and Cdh1 in a cell cycle-dependent manner. Consistent with this, overexpression of Cdc20 or Cdh1 led to a marked reduction of endogenous Mps1 levels during anaphase or G(1) phase, respectively. In contrast, depletion of Cdc20 or Cdh1 by RNAi treatment both led to the stabilization of Mps1 protein during mitosis or G(1) phase, respectively. Finally, we identified a single D-box motif in human Mps1 that is required for its ubiquitination and degradation. Failure to appropriately degrade Mps1 is sufficient to trigger centrosome amplification and mitotic abnormalities in human cells. Thus, our results suggest that the sequential actions of the APC-c(Cdc20) and APC-c(Cdh1) ubiquitin ligases regulate the clearance of Mps1 levels and are critical for Mps1 functions during the cell cycle in human cells.

77 FR 5491 - Endangered and Threatened Species; Initiation of 5-Year Review for Sei Whales

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-03

... Plants, Office of Protected Resources, (301) 427-8471. SUPPLEMENTARY INFORMATION: Section 4(c)(2)(A) of... determination or most recent status review. Categories of requested information include: (1) Species biology...