857 research outputs found
Partition games
We introduce CUT, the class of 2-player partition games. These are NIM type
games, played on a finite number of heaps of beans. The rules are given by a
set of positive integers, which specifies the number of allowed splits a player
can perform on a single heap. In normal play, the player with the last move
wins, and the famous Sprague-Grundy theory provides a solution. We prove that
several rulesets have a periodic or an arithmetic periodic Sprague-Grundy
sequence (i.e. they can be partitioned into a finite number of arithmetic
progressions of the same common difference). This is achieved directly for some
infinite classes of games, and moreover we develop a computational testing
condition, demonstrated to solve a variety of additional games. Similar results
have previously appeared for various classes of games of take-and-break, for
example octal and hexadecimal; see e.g. Winning Ways by Berlekamp, Conway and
Guy (1982). In this context, our contribution consists of a systematic study of
the subclass `break-without-take'
A generalization of Arc-Kayles
The game Arc-Kayles is played on an undirected graph with two players taking
turns deleting an edge and its endpoints from the graph. We study a
generalization of this game, Weighted Arc Kayles (WAK for short), played on
graphs with counters on the vertices. The two players alternate choosing an
edge and removing one counter on both endpoints. An edge can no longer be
selected if any of its endpoints has no counter left. The last player to play a
move wins. We give a winning strategy for WAK on trees of depth 2. Moreover, we
show that the Grundy values of WAK and Arc-Kayles are unbounded. We also prove
a periodicity result on the outcome of WAK when the number of counters is fixed
for all the vertices but one. Finally, we show links between this game and a
variation of the non-attacking queens game on a chessboard
Sol–gel synthesis and characterization of barium (magnesium) aluminosilicate glass sealants for solid oxide fuel cells
Solid oxide fuel cells (SOFC) correspond to efficient energy conversion systems coupled with low emissions of pollutants. In the aim to fabricate high temperature planar SOFC, glass and glass-ceramic sealants are developed to associate several criteria and properties : high thermal expansion (11.0 to 12.0 ⋅ 10− 6 K− 1), high electrical resistance > 2 kΩ/cm2, good thermochemical compatibility with the other active materials of the fuel cell, and stability under H2 and H2O atmospheres at an operation temperature of 800 °C for a long time. According to these requirements, new BAS (BaO–Al2O3–SiO2) and BMAS (BaO–MgO–Al2O3–SiO2) glass-ceramic sealants have been developed by sol–gel route which is a non-conventional process for such applications. By this soft chemistry process, we anticipate a decrease in the glasses processing temperature due to a better homogeneity between cationic precursors in the mixture and a more important reactivity of materials. Experimental results in terms of thermomechanical properties, thermal expansion coefficient, crystalline phase content, and microstructure were discussed. In particular, the influence of the %BaO on the thermomechanical properties of glass-ceramics was described. Changes in properties of glass-ceramics were closely related to the microstructure. The influence of MgO on glass processing temperatures, on the structure and on the microstructure is evaluated in order to confirm that these glass-ceramics are promising candidates to SOFC applications. So, after performing a systematic investigation to the various systems, the properties of suitable glass were proposed
Non-interpenetrated metal-organic frameworks based on copper(II) paddlewheel and oligoparaxylene-isophthalate linkers: synthesis, structure and gas adsorption
Two metal–organic framework materials, MFM-130 and MFM-131 (MFM = Manchester Framework Material), have been synthesized using two oligoparaxylene (OPX) tetracarboxylate linkers containing four and five aromatic rings, respectively. Both fof-type non-interpenetrated networks contain Kagomé lattice layers comprising [Cu2(COO)4] paddlewheel units and isophthalates, which are pillared by the OPX linkers. Desolvated MFM-130, MFM-130a, shows permanent porosity (BET surface area of 2173 m2/g, pore volume of 1.0 cm3/g), high H2 storage capacity at 77 K (5.3 wt% at 20 bar and 2.2 wt% at 1 bar), and a higher CH4 adsorption uptake (163 cm3(STP)/cm3 (35 bar and 298 K)) compared with its structural analogue, NOTT-103. MFM-130a also shows impressive selective adsorption of C2H2, C2H4, and C2H6 over CH4 at room temperature, indicating its potential for separation of C2 hydrocarbons from CH4. The single-crystal structure of MFM-131 confirms that the methyl substituents of the paraxylene units block the windows in the Kagomé lattice layer of the framework, effectively inhibiting network interpenetration in MFM-131. This situation is to be contrasted with that of the doubly interpenetrated oligophenylene analogue, NOTT-104. Calculation of the mechanical properties of these two MOFs confirms and explains the instability of MFM-131 upon desolvation in contrast to the behavior of MFM-130. The incorporation of paraxylene units, therefore, provides an efficient method for preventing network interpenetration as well as accessing new functional materials with modified and selective sorption properties for gas substrates
Nuclear Receptors and the Warburg effect in cancer
In 1927 Otto Warburg established that tumours derive energy primarily from the conversion of glucose to lactic acid and only partially through cellular respiration involving oxygen. In the 1950’s he proposed that all causes of cancer reflected different mechanisms of disabling cellular respiration in favour of fermentation (now termed aerobic glycolysis). The role of aberrant glucose metabolism in cancer is now firmly established. The shift away from oxidative phosphorylation towards the metabolically expensive aerobic glycolysis is somewhat counter-intuitive given its wasteful nature. Multiple control processes are in place to maintain cellular efficiency and it is likely that these mechanisms are disrupted to facilitate the shift to the reliance on aerobic glycolysis. One such process of cell control is mediated by the nuclear receptor superfamily. This large family of transcription factors plays a significant role in sensing environmental cues and controlling decisions on proliferation, differentiation and cell death for example, to regulate glucose uptake and metabolism and to modulate the actions of oncogenes and tumour suppressors. In this review we highlight mechanisms by which nuclear receptors actions are altered during tumorigenic transformation and can serve to enhance the shift to aerobic glycolysis. At the simplest level, a basic alteration in NR behaviour can serve to enhance glycolytic flux thus providing a basis for enhanced survival within the tumour micro-environment. Ameliorating the enhanced NR activity in this context may help to sensitize cancer cells to Warburg targeted therapies and may provide future drug targets
Tailoring porosity and rotational dynamics in a series of octacarboxylate metal-organic frameworks
Modulation and precise control of porosity of metal-organic frameworks (MOFs) are of critical importance to their materials function. Here we report the first modulation of porosity for a series of isoreticular octacarboxylate MOFs, denoted MFM-180 to MFM-185, via a strategy of selective elongation of metal-organic cages. Owing to the high ligand connectivity, these MOFs show absence of network interpenetration, robust structures and permanent porosity. Interestingly, activated MFM-185a shows a record high BET surface area of 4734 m2 g-1 for an octacarboxylate MOF. These MOFs show remarkable CH4 and CO2 adsorption properties, notably with simultaneously high gravimetric and volumetric deliverable CH4 capacities of 0.24 g g-1 and 163 v/v (298 K, 5-65 bar) recorded for MFM-185a due to selective elongation of tubular cages. Dynamics of molecular rotors in deuterated MFM-180a-d16 and MFM-181a-d16 were investigated by variable-temperature 2H solid state NMR spectroscopy to reveal the reorientation mechanisms within these materials. Analysis of the flipping modes of the mobile phenyl groups on the linkers, their rotational rates and transition temperatures, paves the way to controlling and understanding the role of molecular rotors through organic linker design within porous MOF materials
Prenatal dopamine and neonatal behavior and biochemistry
Depressed pregnant women (N=126) were divided into high and low prenatal maternal dopamine (HVA) groups based on a tertile split on their dopamine levels at 20 weeks gestation. The high versus the low dopamine group had lower Center for Epidemiological Studies-Depression Scale (CES-D) scores, higher norepinephrine levels at the 20-week gestational age visit and higher dopamine and serotonin levels at both the 20- and the 32-week gestational age visits. The neonates of the mothers with high versus low prenatal dopamine levels also had higher dopamine and serotonin levels as well as lower cortisol levels. Finally, the neonates in the high dopamine group had better autonomic stability and excitability scores on the Brazelton Neonatal Behavior Assessment Scale. Thus, prenatal maternal dopamine levels appear to be negatively related to prenatal depression scores and positively related to neonatal dopamine and behavioral regulation, although these effects are confounded by elevated serotonin levels.We would like to thank the mothers and infants who participated in this study. This research was supported by a Merit Award (MH#46586) and NIH grant (AT#00370) and Senior Research Scientist Awards(MH#00331 and AT#001585) and a March of Dimes Grant (#12-FYO3-48)to Tiffany Field and funding from Johnson and Johnson Pediatric Institute to the Touch Research Institute
Techno-economic analysis on proton conductor ceramic based technologies for various materials, configurations, applications and products
The increasing global energy consumption, particularly from fossil fuels, has led to environmental concerns linked with the increasing global Greenhouse Gas (GHG) emissions. Renewable energy sources offer a solution but are often intermittent and lack programmability. To tackle this issue, protonic ceramic cells (PCCs) are emerging as a promising technology and also as an alternative to traditional solid oxide cells (SOCs).
This study presents a techno-economic analysis of PCCs’ systems for various applications and scenarios depending also on future scale up and improvements. Different materials, cell architectures, and configurations were considered.
The results, evaluated especially through economic indicators such as the levelized costs of the outputs, demonstrate the potential of PCCs as a clean and sustainable energy conversion technology. Positive results were reached with both current and improved future performances, finally comparing them with the ones of the current available SOCs technology
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