Significant Positive Deviation Research Articles

First-principles demonstration of band filling-induced significant improvement in thermodynamic stability and mechanical properties of Sc_{1-x}Ta_{x}B_{2} solid solutions

Mixtures of different metal diborides in the form of solid solutions are promising materials for hard-coating applications. Herein, we study the mixing thermodynamics and the mechanical properties of AlB_{2}-structured Sc_{1-x}Ta_{x}B_{2} solid solutions using the first-principles method, based on the density functional theory, and the cluster-expansion formalism. Our thermodynamic investigation reveals that the two diborides readily mix with one another to form a continuous series of stable solid solutions in the pseudo-binary TaB_{2}-ScB_{2} system even at absolute zero. Interestingly, the elastic moduli as well as the hardness of the solid solutions show significant positive deviations from the linear Vegard’s rule evaluated between those of ScB_{2} and TaB_{2}. In case of Sc_{1-x}Ta_{x}B_{2}, the degrees of deviation from such linear trends can be as large as 25, 20, and 40% for the shear modulus, the Young’s modulus, and the hardness, respectively. The improvement in the stability as well as the mechanical properties of Sc_{1-x}Ta_{x}B_{2} solid solutions relative to their constituent compounds is found to be related to the effect of electronic band filling, induced upon mixing TaB_{2} with ScB_{2}. These findings not only demonstrate the prominent role of band filling in enhancing the stability and the mechanical properties of Sc_{1-x}Ta_{x}B_{2}, but also it can potentially open up a possibility for designing stable/metastable metal diboride-based solid solutions with superior and widely tunable mechanical properties for hard-coating applications.

Combined effect of rattling and compression on the microwave dielectric properties of B-site 1:3 ordered Li6A7Ti11O32 (A = Zn, Mg) spinels

Dense ceramics of two B-site 1:3 ordering spinels Li6A7Ti11O32 (A = Zn, Mg) with space group P4332 were prepared by solid-state reaction. Raman spectroscopy and XRD analysis revealed why the lattice parameters and volume of Li6Mg7Ti11O32 are abnormally greater than those of Li6Zn7Ti11O32. Li6Zn7Ti11O32 exhibits outstanding microwave dielectric properties (Q × f = 129,600 GHz (8.9 GHz), εr = 20.7, τf = −45 ppm/°C) and a low thermal expansion coefficient (αL) of 5.5 ppm/°C. While Mg-analogue displayed a lower Q × f ∼108,600 GHz (9.1 GHz), a lower αL ∼ 4.9 ppm/°C, a higher εr ∼ 21.9, and a slightly positive offset τf ∼ −21 ppm/°C relative to Li6Zn7Ti11O32. A significant positive deviation of 91.6% was observed between the corrected εr(corr) by the porosity and the calculated εr(C-M) by the Clausius-Mosotti (C-M) equation in the Li1.33xA2-2xTi1+0.67xO4 solid solution. The variation in εr and τf values of Li6A7Ti11O32 (x = 0.5625) compared to Li2ATi3O8 (x = 0.75) might be attributed to the combined effect of rattling and compression cations at A-site and B-site. Moreover, the negative τf of Li6A7Ti11O32 (A = Zn, Mg) ceramics was balanced to near zero by adding CaTiO3.

Effect of chemical composition and atomic configuration on thermodynamic stability and elastic properties of AlB[formula omitted]-type Sc[formula omitted]V[formula omitted]B2 solid solutions: A first-principles investigation

As a promising candidate for hard coating, the thermodynamic stability as well as the elastic properties, of ScB2-VB2 mixtures exhibiting the AlB2-type structure are examined using a combination of the cluster-expansion method and the first-principles calculations. Our prediction reveals that, upon cooling the mixtures to low temperatures, Sc and V atoms displays a strong preference for being surrounded by atoms of the opposite type, which reside in the second coordination shell of the metal sublattice. Such a configurational preference indicates a feasibility to fabricate Sc1−xVxB2 in the form of superlattices, as described by periodic arrangements of ScB2 and VB2 layers of different thickness along the ¡0001¿ direction. Interestingly, the stiffness, shear strength, and hardness of Sc1−xVxB2, where 0.375 ≲x≲ 0.625, in the form either of superlattice structures or of random solid solutions show significant positive deviations from the linear Vegard’s law, which can be understood in terms of the electronic band filling of the bonding states of Sc1−xVxB2. These findings also reveal that the elastic moduli and hardness of Sc1−xVxB2 are governed by the contents of ScB2 and VB2 constituting the mixtures, rather than by the atomic configuration of Sc and V.

A gap in sedimentation in the Silurian section of the Subpolar Urals at the Ludlow-Pridoli boundary

Research subject.The article discusses the results of a new detailed study of a reference section of the Upper Silurian in the Subpolar Urals. This study was undertaken to clarify the existing contradictions concerning the age of the Ludlow-Pridoli boundary deposits and the definition of the Ludlow-Pridoli boundary, which is based on the study of different fauna groups.Materials and methods.The newly collected collections contained more than 100 samples of sedimentary rocks with fossil macro fauna, 22 tests on microfauna, 198 tests on chemical analysis for determining the content of Ba, Sr and δ13C and δ18O isotopes in carbonates. The results of experiments were confirmed by the authors’ bio-sedimentological, paleo-ecological and chemostratigraphic data.Results.The conducted research confirmed the existence of a gap in sedimentation at the end of Ludlow; clarified the thickness of the Sizim stage in the reference section; elucidated its sedimentological and chemostratigraphic characteristics; allowed changes in biodiversity due to a change in the sedimentation regime, paleoecological impact on biota in the late Ludlow and restoration of biota in the early Pridoli to be traced. The study also demonstrated that the time boundaries of the transgressive and regressive stages in the development of the Northern Ural sea basin and the event-stratigraphic boundary of the Ludlow-Pridoli were directly related to the main global events in the Late Silurian (Lau Event, Lower Pridolian Event), the traces of which are preserved in the studied section.Conclusions.The intensification of regressive tendencies across the largest part of the Northern Ural paleobasin in the Late Ludlow, widespread development of microbial biota, cessation of the Silurian reef formation, as well as the extinction of Pentamerida brachiopods – exclusively, indicate a significant ecosystematic restructuring in the late Ludlow. It can be assumed that the absence of a significant positive deviation of the δ13C global Lau Event in this section is associated with the identified gap, the amplitude of which correlates with the Ozarkodina snajdri and Ozarkodina crispa zones located above the Polygnathoides siluricus zone in the conodont sequence of the Upper Ludlow.

Leaf sodium, potassium and electrolyte accumulation capacity of plant species from salt-affected coastal habitats of the Baltic Sea: Towards a definition of Na hyperaccumulation

The aim of the present study was to compare a relatively large number of native plant species from salt-affected coastal habitats with respect to their Na+ and K+ accumulation capacity and electrolyte level in leaves. Sampling sites (77 in total) were chosen during field survey in coastal habitats located at geographically distant places along the Baltic Sea in the territory of Latvia, Estonia, Denmark and Sweden. The main criterion for selection of sampling sites was minimum average soil electrical conductivity (EC) above 200 mS m–1. Leaf samples of 102 taxa (species) from 34 families were collected, with a total number of samples reaching 502, and their water content, Na+ and K+ concentration, and electrical conductivity in water extracts were analyzed. High intraspecies and interspecies variability in analyzed parameters was found. Frequency distribution of Na+ concentration showed highly significant positive asymmetry and deviation from normality. Data on K+ concentration and tissue EC level had asymmetric distribution and deviation from normality but to a lesser extent than that for Na+. Correlation between tissue Na+ concentration and substrate EC at sampling sites was low on individual sample basis but increased to moderate level when mean values of species were analyzed. According to accumulation characteristics of Na+ and K+ in leaves, all species corresponded to one of three general groups: Na+ excluders, regulating EC by changes in K+ concentration; K+ excluders, regulating EC by changes in Na+ concentration; and tight EC regulators; but these features were evident only when intraspecies variability was considered. Na+ concentrations in a range 18 to 30 g kg–1 (on dry biomass basis) and 0.24 to 0.30 mol L–1 (on tissue water basis) can be used as approximate values of a "normal" vs "hyperaccumulation" Na+ range in leaves of coastal plant species of the Baltic Sea.

What can we learn from the global spin alignment of ϕ mesons in heavy-ion collisions?

We propose that a significant positive deviation from 1/3 for the spin density matrix element $\rho_{00}$ of the $\phi$ meson may indicate the existence of a mean field of the $\phi$ meson generated in heavy-ion collisions. This explains why STAR preliminary data for the $\phi$ meson's $\rho_{00}$ are much larger than 1/3 while the data of $\Lambda$ and $\bar{\Lambda}$ polarization seem not to allow such a significant and positive deviation. The contribution may be from the polarization of the strange quark and antiquark through the $\phi$ field, an effective mode of the gluon field in strong interaction. We show that $\rho_{00}$ for the $\phi$ meson is a good analyzer for fields even if they may strongly fluctuate in space-time.

Performance at a Precognitive Remote Viewing Task, with and without Ganzfeld Stimulation: Three Experiments

Recent research by the lead author has sought to incorporate ganzfeld stimulation as part of a remote viewing protocol. An initial exploratory experiment (Roe & Flint, 2007) suggested that novice participants can successfully describe a randomly selected target location while in the ganzfeld but did not make a direct comparison with performance in a waking state. This paper describes a series of three subsequent experiments that compared performance at a remote viewing task in a waking condition with a ganzfeld stimulation condition using a counterbalanced repeated measures design. There were only minor variations in design across the three experiments to enable combination of data in a summary analysis. In total, 110 participants produced 43 hits in the ganzfeld stimulation condition (39.1%), giving a statistically significant positive deviation from chance expectation (sum of ranks = 225, p = .000012), whereas in the waking RV condition they achieved 30 hits (27.3%) which is marginally better than chance expectation (sum of ranks = 253, p = .034). The difference in z scores for target ratings in the two conditions approaches significance (t[39] = 1.865, p = .065). In experiment 1, individual difference measures identified as predictors of psi performance were unrelated to target ratings. Participants completed Pekala’s (1991) Phenomenology of Consciousness Inventory (PCI) in order to gauge their responsiveness to the ganzfeld protocol and of the 12 sub-dimensions tested, ganzfeld performance correlated significantly with greater absorption in their subjective experience, lower physiological arousal and less internal dialogue. In experiments 2 and 3 individual differences measure were replaced by measures of transliminality, openness to experience, and dissociative experiences, but these were also unrelated to task success. Data from experiment 2 did not confirm findings using the PCI from experiment 1, though a significant association was found with the time sense dimension. In experiment 3 no PCI dimensions were correlated with task performance, a pattern which was confirmed when data was combined across all three experiments.

Enthalpy and heat capacity of Cs72.9Bi27.1 alloy with a partly ionic character of interatomic interaction in the condensed state

The enthalpy of solid and liquid Cs72.9Bi27.1 alloy was measured by a mixing method on a massive isothermal drop calorimeter in the temperature range of 432–1177 K. Approximation equations were obtained. The isobaric heat capacity and enthalpy change on melting were determined. The estimated errors for enthalpy and heat capacity were 0.5 and 1.5%, respectively. A significant positive deviation of the caloric properties from the additivity values was established. Tables of recommended values of caloric properties over the range from 298.15 K to 1175 K were developed.

High pressure thermoelasticity and sound velocities of Fe-Ni-Si alloys

The Earth's iron-dominant core is known to contain nickel from cosmochemical analysis and some amount of light elements from geophysical constraints on density and seismic wave velocities. Although there have been several studies to constrain thermoelastic properties of iron-alloys, there has been no systematic study on the effects of nickel and light elements on properties of iron using the same experimental methods and data analysis approach. We conducted nuclear resonant inelastic X-ray scattering and X-ray diffraction experiments on body-centered cubic and hexagonal close-packed (hcp) Fe0.91Ni0.09 and Fe0.8Ni0.1Si0.1 up to 104 GPa and 86 GPa, respectively, and compare to similar measurements conducted on hcp-Fe up to 171 GPa. Specifically, we determine the Debye sound velocity from the low-energy transfer region of the (partial) phonon density of states (DOS) using the equation of state determined for each material and a new approach which utilizes information criteria and probability distributions. Nickel decreases the shear velocity of iron, while 10 at% Si has little to no effect on the shear velocity of Fe0.91Ni0.09. We observe that the shape of the phonon DOS of these alloys remains similar with increasing pressure. In the measured compression range, we therefore apply a generalized scaling law to describe the volume dependence of the phonon DOS and find that the vibrational Grüneisen parameters of hcp-Fe0.91Ni0.09 are nearly indistinguishable from those hcp-Fe and those for Fe0.8Ni0.1Si0.1 trend lower. From the vibrational free energy, we constrain the harmonic vibrational component of thermal pressure, which shows a significant positive deviation from theoretical calculations of hcp-Fe at pressures and temperatures of Earth's core. Collectively, our results demonstrate that the effects of nickel should be considered when modeling iron-rich planetary cores.

Electrochemical Coprecipitation of Zinc and Aluminum in Aqueous Electrolytes for ZnO and AZO Coverage Deposition

The aim of this study is to examine the technological challenge of the electrochemical formation of zinc oxide and Al-doped ZnO films (ZnO:Al, AZO) as transparent conductive oxide coatings with complex architectures for solar cell photoanode materials. A cathodic electrodeposition of AZO was performed using aqueous nitrate electrolytes at 25°C. A significant positive deviation in aluminum percentage in the films was demonstrated by the LAES, EDX, and XPS methods, which originates from aluminum hydroxide sedimentation. The photoluminescent characteristics of the ZnO films reveal low band intensities related to intrinsic defects, while the samples with 1 at.% of aluminum show a strong and wide PL band at 600±80 nm and increase in conductivity.

Can cholinium chloride form eutectic solvents with organic chloride-based salts?

The high melting point of a large number of organic salts with potential ionic liquid-like properties, hinders their applicability as solvents. Considering the success of cholinium chloride on lowering the melting temperature of several substances and its success on forming deep eutectic solvents, this work studies its mixing with organic chlorides to lower their melting points producing eutectic ionic liquids.The solid-liquid phase diagrams for binary mixtures composed of cholinium chloride and ten organic halides were experimentally measured. Surprisingly, cholinium chloride presented, for all these systems, significant positive deviations from ideal liquid behaviour that restricted its ability to lower the melting points of these mixtures. Only for mixtures with ammonium chloride, tetramethylammonium chloride, bis(2-hydroxyethyl)dimethylammonium chloride or cholinium bromide was cholinium chloride able to significantly lower the melting point of the mixture, but without reaching values close to room temperature (298 K). For a better understanding of the results obtained, the solid-liquid phase diagrams of four alkylammonium chloride-based mixtures were experimentally assessed and used to show that these compounds are better than cholinium chloride at inducing negative deviations from ideality, leading to greater melting point depressions.

Solid-State NMR Investigation of Drug-Excipient Interactions and Phase Behavior in Indomethacin-Eudragit E Amorphous Solid Dispersions.

To investigate the nature of drug-excipient interactions between indomethacin (IMC) and methacrylate copolymer Eudragit® E (EE) in the amorphous state, and evaluate the effects on formulation and stability of these amorphous systems. Amorphous solid dispersions containing IMC and EE were spray dried with drug loadings from 20% to 90%. PXRD was used to confirm the amorphous nature of the dispersions, and DSC was used to measure glass transition temperatures (Tg). 13C and 15N solid-state NMR was utilized to investigate changes in local structure and protonation state, while 1H T1 and T1ρ relaxation measurements were used to probe miscibility and phase behavior of the dispersions. Tg values for IMC-EE solid dispersions showed significant positive deviations from predicted values in the drug loading range of 40-90%, indicating a relatively strong drug-excipient interaction. 15N solid-state NMR exhibited a change in protonation state of the EE basic amine, with two distinct populations for the EE amine at -360.7ppm (unprotonated) and -344.4ppm (protonated). Additionally, 1H relaxation measurements showed phase separation at high drug load, indicating an amorphous ionic complex and free IMC-rich phase. PXRD data showed all ASDs up to 90% drug load remained physically stable after 2years. 15N solid-state NMR experiments show a change in protonation state of EE, indicating that an ionic complex indeed forms between IMC and EE in amorphous solid dispersions. Phase behavior was determined to exhibit nanoscale phase separation at high drug load between the amorphous ionic complex and excess free IMC.

Relationship between mean annual temperatures and precipitation sums in Montenegro between 1951-1980 and 1981-2010 periods

In the second half of the 20th and by the beginning of the 21st century the area of Montenegro was dominated by positive air temperature fluctuations and negative precipitation sums. This paper analyses a 60-year period (1951-2010), with the aim to determine air temperature and precipitation deviation between the two 30-year periods: 1951-1980 and 1981-2010. Calculations of mean, mean maximum and mean minimum temperature have been done, as well as annual values of precipitation sums. All three temperature parameters, particularly maximum values, show that the 1981-2010 period was significantly warmer in relation to previous three decades. Significant changes in mean annual precipitation sums between the two observation periods have been recorded on the coast and, locally, in the western part of the country. The results also showed that there was a significant increase in positive deviations of mean maximum temperature in most parts of Montenegro during the 1981-2010 period in relation to the 1951-1980 period, while changes of this type in other observation parameters were mostly minor.

Stability of Preharvest Sprouting Responses in Great Plains Hard Winter Wheats as Inferred from a Surrogate Assay

Preharvest sprouting, or precocious germination before grain is harvested, has negative consequences on wheat (Triticum spp.) production and utilization industries. Both genetic and environmental factors predispose wheat genotypes to preharvest sprouting. Using a surrogate assay involving misting of intact spikes, 13 Great Plains adapted winter wheat genotypes were evaluated in terms of environmental stability of preharvest sprouting responses using regression analysis. All entries demonstrated slopes with significant differences from zero, indicating that all responded to changing environments. Entries, however, differed markedly in their responses, with several lines demonstrating slopes with significant negative or positive deviations from 1.0. The hard red winter wheat (Triticum aestivum L.) ‘Camelot’ and the hard white wheat ‘Nuplains’ were found to be most stable (e.g., least responsive) to changing environments. Regression models from stability analyses of these two cultivars were used to identify newly developed genetic materials with potential preharvest sprouting tolerance. Several potential tolerant breeding lines and cultivars were identified and added to the USDA‐ARS National Small Grains Collection, expanding the genetic diversity of useful parental materials capable of contributing to an increase in the frequency of tolerance genes across Great Plains breeding programs.

Non-stationarities in the relationships of heavy precipitation events in the Mediterranean area and the large-scale circulation in the second half of the 20th century

In the context of analyzing temporal varying relationships of heavy precipitation events in the Mediterranean area and associated anomalies of the large-scale circulation, quantile regression models were established. The models were calibrated using different circulation and thermodynamic variables at the 700hPa and 850hPa levels as predictors as well as daily precipitation time series at different stations in the Mediterranean area as predictand. Analyses were done for the second half of the 20th century. In the scope of assessing non-stationarities in the predictor-predictand relationships the time series were divided into calibration and validation periods. 100 randomized subsamples were used to calibrate/validate the models under stationary conditions. The highest and lowest skill score of the 100 random samples was used to determine the range of random variability. The model performance under non-stationary conditions was derived from the skill scores of cross-validated running subintervals. If the skill scores of several consecutive years are outside the range of random variability a non-stationarity was declaimed. Particularly the Iberian Peninsula and the Levant region were affected by non-stationarities, the former with significant positive deviations of the skill scores, the latter with significant negative deviations. By means of a case study for the Levant region we determined three possible reasons for non-stationary behavior in the predictor-predictand relationships. The Mediterranean Oscillation as a superordinate system affects the cyclone activity in the Mediterranean basin and the location and intensity of the Cyprus low. Overall, it is demonstrated that non-stationarities have to be taken into account within statistical downscaling model development.

The Motivational Influence of Milestone Times on 10-km Running Performance

To date, little research has been conducted to evaluate the potentially motivating effect of completing a race at a specific “milestone” finishing time. As this is difficult to perform in a laboratory setting, we examined 10-km runners from a large cohort to see if they were more likely to complete a race before rather than after a set milestone time (40:00, 45:00, and 50:00). Frequency distributions for finishers of each sex were created in 30-second time groups, with ideal normal distributions modeled based on this data. The actual time group frequencies were compared to the “expected” values from the modeled normal distributions. We included time groups that contained at least 1,000 finishers, thus were constrained to 36:00 – 52:00 for men and 43:30 to 52:00 for women. A total of 180,731 men and 53,047 women were included in the analysis. Men showed significant positive deviations (more finishers than expected) in the 39:30-40:00, 44:30-45:00, and 48:30-50:00 time groups (3 groups); they showed significant negative deviations only at 40:00-40:30 and 50:00-50:30. Women only showed significant positive time group deviations from 48:30-50:00 (1 group) with no significant negative deviations. In conclusion, despite the relatively arbitrary nature of milestones, they appear to exert a motivational influence on 10-km runners.

The physical and mechanical properties and cure characteristics of NBR/silica/MWCNT hybrid composites

The main objective of the present study was to investigate the synergistic effect of simultaneous use of two reinforcing fillers in rubber compounds based on acrylonitrile-butadiene copolymer (NBR). Silica was used as reinforcing filler in all samples and the loading content was 25 phr. 3 and 5 phr of multiwall carbon nanotubes (MWCNT) were used as second reinforcing filler in NBR/silica compounds. Melt mixing method was employed for compound preparation. The effects of carbon nanotube/silica hybrid filler on mechanical and vulcanization characteristics of the rubber compounds were investigated. These results revealed that addition of the reinforcing filler, either carbon nanotube or silica, shortened the optimum cure time (t 90) and also scorch time (t s1) of samples compared to that of pure NBR compound. In hybrid compounds, the reduction in optimum cure time and scorch time was higher than that of for silica-filled NBR or CNT-filled NBR compounds. This can be attributed to the synergistic effect between CNT and silica as two reinforcing agents in NBR compounds. Regardless the composition of the reinforcing filler, an increase of the relaxed storage modulus is observed, while the tan δ value is decreased steadily. The dynamic modulus reinforcement of nanocomposites was examined by the Guth Gold and Modified Guth Gold equations. For hybrid samples, the experimental values show a significant positive deviation from model predictions. According to the Barlow’s formula, hybrid compounds show higher burst strength compared to silica or CNT filled NBR compounds.

Titania Supported Ru Nanoclusters as Catalysts for Hydrodeoxygenation of Pyrolysis Oils

This study evaluates: (1) Ru-containing catalysts for low temperature hydrogenation of acetic acid in aqueous medium to simulate hydrogenating bio-derived oils, and (2) the development of the role of ruthenium–titania (Ru–TiO2) catalytic interaction for this system. A series of 9 catalysts was screened, and a comparison of selectivity versus conversion indicated that selectivity was a function of conversion, with ethanol being the predominant product at low conversion, and light gases being favored at higher conversion by secondary reactions. Exponential trend curves for ethanol (decay) and methane (increase) with conversion were fitted. On a per gram catalyst basis, the most active catalyst under study in the temperature range of 120° through 220 °C with a hydrogen partial pressure of 1000 psi (7.0 MPa) was 5 % Ru on carbon; however, its selectivity for the conversion to ethanol was exceptionally low (5 % selectivity at ~70 % conversion and 180 °C) with the primary products being ethane and methane. This catalyst formulation displayed a negative deviation from the trend curve for ethanol and a higher methane selectivity deviation. On the other hand, a catalyst of Ru prepared by atomic layer deposition (i.e., Ru(ALD)/Ti(ALD)/Nb/Si) was also highly active (~55 % conversion at 180 °C) but displayed a significant positive deviation from the trend curve (~40 % selectivity). These results combined with those of EXAFS suggest that the interface between the deposited Ru and the titania support may be responsible for the increase in selectivity to ethanol. In general, the catalysts prepared by ALD were more active on a per gram catalyst basis than the catalysts prepared by standard aqueous impregnation. Samples of catalyst that were observed using transmission electron microscopy confirmed that the Ru was well dispersed in that no Ru nanoparticle morphology was observed within the resolving power of the JEOL JEM-3010 TEM instrument. Regarding the nanostructure of the support, TEM measurements revealed that the ALD method resulted in support domain sizes that were significantly smaller ( 10 nm), promoting defect formation. EXAFS characterization indicated that the best ALD catalyst (i.e., Ru(ALD)/Ti(ALD)/Nb/Si) had higher dispersion (i.e., smaller nanoparticles and thus greater metal-support interface) than the reference catalysts prepared by aqueous impregnation. A Ru-Osupport contribution was required in order to obtain an acceptable EXAFS fit (‘the long metal–oxygen bond’). Increases in Ru–Ru coordination along with decreases in Ru-Osupport coordination were observed for longer catalyst aging times and higher treatment temperatures. In summary, the selectivity to ethanol during hydrogenation of acetic acid was promoted by preparing finely dispersed Ru particles in close interaction with nanoscale titania domains. The hydrogenation of the bio-model compound, acetic acid, over Ru-deposited catalyst leads to ethanol and methane/ethane. Based on XANES/EXAFS results, the reaction on finely dispersed Ru interacting with titania leads to the preferred product, ethanol, while larger Ru metal particles in the absence of contact between Ru and titania leads towards the formation of light hydrocarbon gases.

Measurements of C1–C4 alkyl nitrates and their relationships with carbonyl compounds and O3 in Chinese cities

Ambient alkyl nitrates (RONO2) are important byproducts of O3 formation. Although concern about O3 pollution has increased recently, few studies have investigated RONO2 chemistry and distributions in China. In this study, ambient levels of C1–C4 RONO2 were measured in Chinese cities, and their relationships with parent hydrocarbons (RH), carbonyls, and total oxidant (Ox = O3 + NO2) were investigated. Our measurements showed that 2-butyl nitrate (2-BuONO2) was the most abundant RONO2 species, with mixing ratios of 48–88 pptv, followed by 2-propyl nitrate (2-PrONO2), ethyl nitrate (EtONO2), methyl nitrate (MeONO2), and 1-propyl nitrate (1-PrONO2). The measured RONO2 species exhibited maximum levels in the early afternoon (13:00–14:00) of summer, suggesting the importance of RONO2 photochemical production. Relative to 2-BuONO2/n-butane, the measured 1-PrONO2/propane agreed well with the modeled ratio based on laboratory kinetic data, suggesting that propane was the dominant precursor of ambient 1-PrONO2. However, the measured ratios for MeONO2/methane, EtONO2/ethane, and summertime 2-PrONO2/propane showed significant positive deviations from the predicted values, indicating the existence of additional sources other than OH oxidation of the parent hydrocarbons. Initial mixing ratios of C1–C3 carbonyls during 08:00–12:00 in summer at the PKU site exhibited significant correlations with RONO2 levels, suggesting the importance of secondary sources for ambient carbonyls. The measured ratios of formaldehyde/MeONO2 were close to the theoretical ratio, whereas the derived ratios for acetaldehyde/EtONO2, propanal/1-PrONO2, and acetone/2-PrONO2 were higher than the kinetic ratios, indicating that these carbonyls might be produced from sources other than the reaction of alkoxy radicals with O2. Carbonyls are important precursors of Ox, but their photochemical reactions do not result in RONO2 production. Therefore, Ox/RONO2 could indicate the relative importance of carbonyls to Ox formation. On the basis of the measured ratios of Ox/2-BuONO2, we estimated the maximum contributions of secondary carbonyls to Ox at the PKU site to be 25–32% during 12:00–16:00 in summer.

Effects to salt tolerance of GILI tilapia(O.niloticus×S.melanotheron)and its two parents in the chronic salinity stress experiment

In order to further study salt tolerance performance of a hybrid by Oreochromis niloticus(♀)×Sarotherodon melanotheron(♂)which had been examined and approved by China National Aquaculture Variety Approval Committee as a new variety for aquaculture and named tilapiain 2009,researches have been carried out to study the salt tolerance in the chronic salinity stress experiment to GILI tilapia and its two parents,the differences of salt tolerance performance of three kinds of tilapia are analysed,and the regression model between mortality of salt tolerance in the chronic salinity stress and death of time,death of salinity are established.The results of the study show that:(1)There are significant differences in capacity of salt tolerance among three kinds of tilapia,the performance of salt tolerance of GILI tilapia is close to S.melanotheron,it is much higher than O.niloticus,the average death salinity of three kinds of tilapia when they are domesticated in salt are 57.9,66.7 and 18.5 respectively.(2)There are the greatest differences of death time domesticated among individuals in O.niloticus,it is the least in S.melanotheron,it is medium in GILI tilapia.There are the most significant normal negative deviation in GILI tilapia and S.melanotheron,there are the more values of outlier and extremum,O.niloticus has a significant normal positive deviation,it has outlier values,no extremum values.(3)The regression relationships between the mortality of chronic salinity stress to salt and the death time,death salinity of three kinds of tilapia are fit for single-element regression model,the single-element regression model between the salt tolerance mortality(Y)and the domestication time of death(t)and salinity of death(s)of GILI tilapia are growth model Y=e(-7.694+0.031t)(R2=0.979)and quadratic model Y=0.542-0.037s+0.001s2(R2=0.950)respectively.