A comment on Baxter condition for commutativity of transfer matrices

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

Gutkin, E.

1986-07-01

Let T..nu.. and T'..nu.. be the transfer matrices of two vertex models corresponding to two sets of Boltzmann weights. The Baxter condition on Boltzmann weights was known to be sufficient for commutativity of T..nu.. and T'..nu.. for all ..nu... We show that generically it is also necessary.

Ethylene formation by dehydration of ethanol over medium pore zeolites

NASA Astrophysics Data System (ADS)

Gołąbek, Kinga; Tarach, Karolina A.; Filek, Urszula; Góra-Marek, Kinga

2018-03-01

In this work, the role of pore arrangement of 10-ring zeolites ZSM-5, TNU-9 and IM-5 on their catalytic properties in ethanol transformation were investigated. Among all the studied catalysts, the zeolite IM-5, characterized by limited 3-dimensionality, presented the highest conversion of ethanol and the highest yields of diethyl ether (DEE) and ethylene. The least active and selective to ethylene and C3 + products was zeolite TNU-9 with the largest cavities formed on the intersection of 10-ring channels. The catalysts varied, however, in lifetime, and their deactivation followed the order: IM-5 > TNU-9 > ZSM-5. The processes taking place in the microporous zeolite environment were tracked by IR spectroscopy and analysed by the 2D correlation analysis (2D COS) allowing for an insight into the nature of chemisorbed adducts and transition products of the reaction. The cage dimension was found as a decisive factor influencing the tendency for coke deposition, herein identified as polymethylated benzenes, mainly 1,2,4-trimethyl-benzene.

Ethylene formation by dehydration of ethanol over medium pore zeolites.

PubMed

Gołąbek, Kinga; Tarach, Karolina A; Filek, Urszula; Góra-Marek, Kinga

2018-03-05

In this work, the role of pore arrangement of 10-ring zeolites ZSM-5, TNU-9 and IM-5 on their catalytic properties in ethanol transformation were investigated. Among all the studied catalysts, the zeolite IM-5, characterized by limited 3-dimensionality, presented the highest conversion of ethanol and the highest yields of diethyl ether (DEE) and ethylene. The least active and selective to ethylene and C 3+ products was zeolite TNU-9 with the largest cavities formed on the intersection of 10-ring channels. The catalysts varied, however, in lifetime, and their deactivation followed the order: IM-5>TNU-9>ZSM-5. The processes taking place in the microporous zeolite environment were tracked by IR spectroscopy and analysed by the 2D correlation analysis (2D COS) allowing for an insight into the nature of chemisorbed adducts and transition products of the reaction. The cage dimension was found as a decisive factor influencing the tendency for coke deposition, herein identified as polymethylated benzenes, mainly 1,2,4-trimethyl-benzene. Copyright © 2017 Elsevier B.V. All rights reserved.

Achieving Lower Nitrogen Balance and Higher Nitrogen Recovery Efficiency Reduces Nitrous Oxide Emissions in North America's Maize Cropping Systems

PubMed Central

Omonode, Rex A.; Halvorson, Ardell D.; Gagnon, Bernard; Vyn, Tony J.

2017-01-01

Few studies have assessed the common, yet unproven, hypothesis that an increase of plant nitrogen (N) uptake and/or recovery efficiency (NRE) will reduce nitrous oxide (N2O) emission during crop production. Understanding the relationships between N2O emissions and crop N uptake and use efficiency parameters can help inform crop N management recommendations for both efficiency and environmental goals. Analyses were conducted to determine which of several commonly used crop N uptake-derived parameters related most strongly to growing season N2O emissions under varying N management practices in North American maize systems. Nitrogen uptake-derived variables included total aboveground N uptake (TNU), grain N uptake (GNU), N recovery efficiency (NRE), net N balance (NNB) in relation to GNU [NNB(GNU)] and TNU [NNB(TNU)], and surplus N (SN). The relationship between N2O and N application rate was sigmoidal with relatively small emissions for N rates <130 kg ha−1, and a sharp increase for N rates from 130 to 220 kg ha−1; on average, N2O increased linearly by about 5 g N per kg of N applied for rates up to 220 kg ha−1. Fairly strong and significant negative relationships existed between N2O and NRE when management focused on N application rate (r2 = 0.52) or rate and timing combinations (r2 = 0.65). For every percentage point increase, N2O decreased by 13 g N ha−1 in response to N rates, and by 20 g N ha−1 for NRE changes in response to rate-by-timing treatments. However, more consistent positive relationships (R2 = 0.73–0.77) existed between N2O and NNB(TNU), NNB(GNU), and SN, regardless of rate and timing of N application; on average N2O emission increased by about 5, 7, and 8 g N, respectively, per kg increase of NNB(GNU), NNB(TNU), and SN. Neither N source nor placement influenced the relationship between N2O and NRE. Overall, our analysis indicated that a careful selection of appropriate N rate applied at the right time can both increase NRE and reduce N2O

Colored-noise-induced discontinuous transitions in symbiotic ecosystems

NASA Astrophysics Data System (ADS)

Mankin, Romi; Sauga, Ako; Ainsaar, Ain; Haljas, Astrid; Paunel, Kristiina

2004-06-01

A symbiotic ecosystem is studied by means of the Lotka-Volterra stochastic model, using the generalized Verhulst self-regulation. The effect of fluctuating environment on the carrying capacity of a population is taken into account as dichotomous noise. The study is a follow-up of our investigation of symbiotic ecosystems subjected to three-level (trichotomous) noise [

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

Xu, J.; Bugaris, D. E.; Xiao, Z. L.

We report the occurrence of reentrantmetallic behavior in theWeyl semimetal NbP. When the appliedmagnetic field H is above a critical value H-c, a reentrance appears as a peak in the temperature-dependent resistivity rho(xx) (T) at T = T-p, similar to that observed in graphite where it was attributed to local superconductivity. The Tp(H) relationship follows a power-law dependence T-p similar to (H-H-c)(1/nu) where. can be derived from the temperature dependence of the zero-field resistivity rho(0)(T) similar to T-nu. From concurrent measurements of the transverse rho(xx) (T) and Hall rho(xy)(T) magnetoresistivities, we reveal a clear correlation between the rapidly increasing rho(xy)more » (T) and the occurrence of a peak in the rho(xx) (T) curve. Quantitative analysis indicates that the reentrantmetallic behavior arises from the competition of the magnetoconductivity sigma(xx) (T) with an additional component Delta sigma(xx) (T) = kappa(H)sigma(xx)(T) where kappa(H) = [rho(xy)(T)/rho(xx)(T)](2) is the Hall factor. We find that the Hall factor (kappa(H) approximate to 0.4) at peak temperature T-p is nearly field independent, leading to the observed T-p (H) relationship. Furthermore, the reentrant metallic behavior in rho(xx) (T) also is reflected in the behavior of rho(xx) (H) that ranges from nonsaturating at T > 70K to saturation at liquid-helium temperatures. The latter can be explained with the magnetic field dependence of the Hall factor kappa(H) (H). Our paper demonstrates that a semiclassical theory can account for the "anomalies" in the magnetotransport phenomena of NbP without invoking an exotic mechanism.« less

Expected geoneutrino signal at JUNO

NASA Astrophysics Data System (ADS)

Strati, Virginia; Baldoncini, Marica; Callegari, Ivan; Mantovani, Fabio; McDonough, William F.; Ricci, Barbara; Xhixha, Gerti

2015-12-01

Constraints on the Earth's composition and on its radiogenic energy budget come from the detection of geoneutrinos. The Kamioka Liquid scintillator Antineutrino Detector (KamLAND) and Borexino experiments recently reported the geoneutrino flux, which reflects the amount and distribution of U and Th inside the Earth. The Jiangmen Underground Neutrino Observatory (JUNO) neutrino experiment, designed as a 20 kton liquid scintillator detector, will be built in an underground laboratory in South China about 53 km from the Yangjiang and Taishan nuclear power plants, each one having a planned thermal power of approximately 18 GW. Given the large detector mass and the intense reactor antineutrino flux, JUNO aims not only to collect high statistics antineutrino signals from reactors but also to address the challenge of discriminating the geoneutrino signal from the reactor background. The predicted geoneutrino signal at JUNO is terrestrial neutrino unit (TNU), based on the existing reference Earth model, with the dominant source of uncertainty coming from the modeling of the compositional variability in the local upper crust that surrounds (out to approximately 500 km) the detector. A special focus is dedicated to the 6° × 4° local crust surrounding the detector which is estimated to contribute for the 44% of the signal. On the basis of a worldwide reference model for reactor antineutrinos, the ratio between reactor antineutrino and geoneutrino signals in the geoneutrino energy window is estimated to be 0.7 considering reactors operating in year 2013 and reaches a value of 8.9 by adding the contribution of the future nuclear power plants. In order to extract useful information about the mantle's composition, a refinement of the abundance and distribution of U and Th in the local crust is required, with particular attention to the geochemical characterization of the accessible upper crust where 47% of the expected geoneutrino signal originates and this region contributes

Water quality and pollution status of Chambal river in National Chambal Sanctuary, Madhya Pradesh.

PubMed

Saksena, D N; Garg, R K; Rao, R J

2008-09-01

The physico-chemical characteristics of Chambal river water in National Chambal sanctuary (Madhya Pradesh) have been studied. The stretch of Chambal river contained in the National Chambal sanctuary (located at 25 degrees 23'-26 degrees 52'N, 76 degrees 28'-79 degrees 15'E) is extending up to 600 km downstream from Kota (Rajasthan) to the confluence of the Chambal with Yamuna river (Etawah). The river flow in Madhya Pradesh spans up to approximately 400 km. Three sampling stations viz., Station A--near Palighat, district Sheopurkalan, Station B--near Rajghat, district Morena and Station C--near Baraighat, district Bhind were established for the collection of water samples during April, 2003 to March, 2004. The water quality parameters namely transparency (12.12-110 cm), colour (transparent-very turbid), turbidity (1-178 TNU), electrical conductivity (145.60-884 microS cm(-1)), total dissolved solids (260-500 mgl(-1)), pH (7.60-9.33), dissolved oxygen (4.86-14.59 mgl(-1)), free carbon dioxide (0-16.5 mgl(-1)), total alkalinity (70-290 mgl(-1)), total hardness (42-140 mgl(-1)), chloride (15.62-80.94 mgl(-1)), nitrate (0.008-0.025 mgl(-1)), nitrite (0.002-0.022 mgl(-1)), sulphate (3.50-45 mgl(-1)), phosphate (0.004-0.050 mgl(-1)), silicate (2.80-13.80 mgl(-1)), biochemical oxygen demand (0.60-5.67 mgl(-1)), chemical oxygen demand (2.40-26.80 mgl(-1)), ammonia (nil-0.56 mgl(-1)), sodium (14.30-54.40 mgl(-1)) and potassium (2.10 mgl(-1)-6.30 mgl(-1)) reflects on the pristine nature of the river in National Chambal sanctuary. On the basis of various parameters studied, Chambal river in this stretch can be placed under the category of oligosaprobic. The water quality analysis, indicated that the riverwater in the sanctuary area is pollution free and can serve as a good habitat for many aquatic animals including endangered species.