Lx Values Research Articles

An extremal problem in subsequence sum

Let N denote the set of all positive integers and let N0=N⋃{0}. For a strictly increasing sequence A of positive integers, let P(A) be the set of all integers which can be represented as the finite sum of distinct terms of A. Fix an integer b such that b∈{1,2,4,7,8} or b≥11. For every integer k≥1, define inductively ck(b) as the smallest positive integer r so that there exist two strictly increasing sequences A={ai}i=1∞ and B={bi}i=1∞ of positive integers such that (1) b1=c1(b)=b,b2=c2(b)=3b+5; (2) bi=ci(b) for all 3≤i≤k−1 and bk=r; (3) P(A)=N0∖{bi:i∈N} and ai≤∑j<iaj+1 for all ai≥b+1. Furthermore, let C(b):={ck(b):k∈N} and A(b):={A:AisastrictlyincreasingsequenceofpositiveintegerssuchthatP(A)=N0∖C(b)}. For any positive real number x, we let A(x) denote the number of terms no more than x in the sequence A and define Lx(b):=minA∈A(b)A(x). In this paper, we determine the exact value of Lx(b) for any positive real number x, and give a characterization on the strictly increasing sequence A of positive integers such that P(A)=N0∖C(b) and A(x)=Lx(b) for any positive real number x≥c1(b)−1.

Effects of Two Different Isolates of Entomopathogen Fungus, Beauveria bassiana (Balsamo) Vuillemin on Myzus persicae Sulzer (Hemiptera: Aphididae)

The study aimed to determine the effectivity of LD.2016 and M6-4 isolates of entomopathogen Beauveria bassiana on Myzus persicae Sulzer (Hemiptera: Aphididae). In this context, the doses of 106, 107 and 108 conidia mL-1 for isolates were used. Experiments for each dose and a control group were set up to be 50 repeats. As a result of the analysis, the rm values of the individuals exposed to 106, 107 and 108 conidia mL-1 doses were calculated as 0.340, 0.352 and 0.337 females/female/day, respectively for the LD.2016 isolate, and 0.292, 0.263 and 0.268 females/female/day, respectively for the M6-4 isolate. The value was 0.280 females/female/day for the control group. By increased dose, the values of lx and mx parameters were decreased, too. Besides, the Weibull and Enkegaard models were applied on the lx and mx values of the populations exposed to entomopathogen isolates. Consequently, it is thought that the isolates of entomopathogen B. bassiana, less harmful to humans and the environment, can be used as a biological control agent in an integrated pest management program for the controlling of the pest.

Z-Shaped toroidal dipole planar terahertz metasurfaces

We proposed and fabricated a Z-shaped toroidal dipole terahertz metasurfaces, consisting of two incomplete U-shaped split rings, and the two incomplete U-shapes are rotationally symmetric with respect to the Z-axis. The effects of the structural parameters on the electromagnetic characteristics of toroidal resonances are investigated via simulation and experiment. The mechanism of toroidal dipole resonance is studied deeply by establishing an LC resonance model and calculating the multipoles scattering energy. The capacitance was highly depended on the value of lx, and the inductance was determined by the value of ly. Hence, the red shift was observed as the increasing of ly/lx. The resonant frequency of the toroidal dipole resonance is red shifted, as the ly/lx of the metallic pattern increases. The tunability of toroidal dipole resonant frequencies explores the interaction of toroidal multipoles with terahertz wave that could have extensive applications in the terahertz functional devices.

Determining the lx and estimating the force of mortality for children under five in Bangladesh

Background: Under-five mortality is a health indicator in population health and the health sciences. Force of death is a more accurate measure of mortality than others, which indicates the situation of mortality when time tends to zero. The purpose of this research is to construct a simulation for lx (the number of people living at exact age x) for under-five mortality in Bangladesh as a whole, and separately for rural and urban areas, and then estimating the mortality rate in regard to these matched models. Methods: Secondary data were collected from Bangladesh Demographic and Health Survey 2007. A polynomial model was selected to match the lx values. To prove the accuracy of the model, the rule of cross-validity was applied. Results: It has been shown that fourth degree polynomial models can be adjusted to lx values ​​with explanation of more than 94% variation. It was noted that the mortality rate shows a rapidly decreasing pattern for people aged 0-20 months, a monotonically increasing pattern for those aged 20-53.5 months and then it begins to decrease. It is found that the mortality rate in rural areas is higher than in urban areas of all ages. Conclusions: It has been shown that the mortality rate in rural areas is higher than for urban areas of all ages, except for those aged 53.5 months. The health situation should therefore be improved to reduce mortality in rural Bangladesh.

Long-Term Leaching Behavior of Petroleum Sludge Waste Containing Palm Oil Fuel Ash and Quarry Dust by Using Solidification/Stabilization Method

In recent years, petroleum industry has generated huge amount of petroleum sludge. There are many types of treatment method in petroleum sludge (PS) and one of the treatments that arise the attention to treat the sludge is solidifica-tion/stabilization (S/S) method as it immobilizes and stabilizes the hazardous substances within a solid matrices. The main objectives of this research are to formulate the correct mixture of PS in S/S matrices and to stimulate the long-term leaching behaviour of S/S matrices in PS treatment with palm oil fuel ash (POFA) and quarry dust (QD) as partial cement and sand replacement respectively. The characterization of PS, POFA and QD were done by using X-Ray Fluorescence (XRF). Furthermore, different percentages of petroleum sludge (control, 0%, 5%, 10%, 20%, 30%) were incorporated with fixed 10% of POFA and 20% of QD replacement into S/S matrices. This research also includes a comparison of two different leaching test parameters such as liquid to surface area ratio, pH, and type of leaching solution on the samples. The leaching test conducted namely are Semi-Dynamic Leaching procedure (SDLP) and Static Leaching Test (SLT). The leachability results from SDLP and SLT indicated that all concentration for nine (9) heavy metals were below the permissible limit set by United States Environmental Protection Agency (USEPA, 1996) standards. In addition, the S/S effectiveness was evaluated by measuring effective diffusion coefficients (De) and leachability index (Lx). Results of S/S treatment shown that De values were lower and Lx values were higher than 8 thus the S/S can be disposed in sanitary landfill. As a conclusion, the results for the leaching behaviour of PS up to 10% incorporated with 10% of POFA replacement in cement and 20% of QD replacement in sand demonstrated minimum leaching of the heavy metals from S/S matrices. This indicated that S/S method could be an alternative disposal method for PS and has potential for replacing other treatment methods that applied at treatment stage for petroleum refinery effluents.

Long-Term Leaching Behavior Of Petroleum Sludge Waste Containing Palm Oil Fuel Ash And Quarry Dust By Using Solidification/Stabilization Method

In recent years, petroleum industry has generated huge amount of petroleum sludge. There are many types of treatment method in petroleum sludge (PS) and one of the treatments that arise the attention to treat the sludge is solidification/stabilization (S/S) method as it immobilizes and stabilizes the hazardous substances within a solid matrices. The main objectives of this research are to formulate the correct mixture of PS in S/S matrices and to stimulate the long-term leaching behaviour of S/S matrices in PS treatment with palm oil fuel ash (POFA) and quarry dust (QD) as partial cement and sand replacement respectively. The characterization of PS, POFA and QD were done by using X-Ray Fluorescence (XRF). Furthermore, different percentages of petroleum sludge (control, 0%, 5%, 10%, 20%, 30%) were incorporated with fixed 10% of POFA and 20% of QD replacement into S/S matrices. This research also includes a comparison of two different leaching test parameters such as liquid to surface area ratio, pH, and type of leaching solution on the samples. The leaching test conducted namely are Semi-Dynamic Leaching procedure (SDLP) and Static Leaching Test (SLT). The leachability results from SDLP and SLT indicated that all concentration for nine (9) heavy metals were below the permissible limit set by United States Environmental Protection Agency (USEPA, 1996) standards. In addition, the S/S effectiveness was evaluated by measuring effective diffusion coefficients (De) and leachability index (Lx). Results of S/S treatment shown that De values were lower and Lx values were higher than 8 thus the S/S can be disposed in sanitary landfill. As a conclusion, the results for the leaching behaviour of PS up to 10% incorporated with 10% of POFA replacement in cement and 20% of QD replacement in sand demonstrated minimum leaching of the heavy metals from S/S matrices. This indicated that S/S method could be an alternative disposal method for PS and has potential for replacing other treatment methods that applied at treatment stage for petroleum refinery effluents.

Ultraviolet photo-ionisation in far-infrared selected sources

It has been reported that there is a deficit of stellar heated dust, as evident from the lack of far-infrared (FIR) emission, in sources within the Herschel-SPIRE sample with X-ray luminosities exceeding a critical value of LX ∼ 1037 W. Such a scenario would be consistent with the suppression of star formation by the AGN, required by current theoretical models. Since absorption of the 21 cm transition of neutral hydrogen (H I), which traces the star-forming reservoir, also exhibits a critical value in the ultraviolet band (above ionising photon rates of Q ≈ 3 × 1056 s−1), we test the SPIRE sample for the incidence of the detection of 250 μm emission with Q. The highest value at which FIR emission is detected above the SPIRE confusion limit is Q = 8.9 × 1057 s−1, which is ≈30 times that for the H I, with no critical value apparent. Since complete ionisation of the neutral atomic gas is expected at Q ≳ 3 × 1056 s−1, this may suggest that much of the FIR must arise from heating of the dust by the AGN. However, integrating the ionising photon rate of each star over the initial mass function, we cannot rule out that the high observed ionising photon rates are due to a population of hot, massive stars.

Applicability of Taylor’s Hypothesis for Estimating the Mean Streamwise Length Scale of Large-Scale Structures in the Near-Neutral Atmospheric Surface Layer

A field investigation of the mean streamwise length scale Lx of large-scale structures and the convection velocity is performed in a high-Reynolds-number (Reτ ~ 106) atmospheric surface layer (ASL). Based on selected high-quality synchronous data obtained at different streamwise positions, the length scale Lx and global convection velocity Uc are extracted in the logarithmic region of the near-neutral ASL at heights of 0.9 m, 1.71 m, 3.5 m, and 5 m. It is found that Uc values are approximately 16% greater than the local mean streamwise velocity component U, and the value of Lx obtained from spatially-separated measurements is greater than the results estimated from Taylor’s hypothesis using the value of U at the four heights. The mean relative difference between the value of Lx and the results estimated by Taylor’s hypothesis using the value of U is approximately 15%. However, the relative difference between the value of Lx and the results estimated from Taylor’s hypothesis using the convection velocity Uc instead of the mean streamwise velocity component U is reduced to 1 ± 6% (≈ zero). Thus, the convection velocity Uc is more appropriate than the mean streamwise velocity component U in obtaining Lx values in the near-neutral ASL.

Active Galactic Nuclei Feedback and the Origin and Fate of the Hot Gas in Early-type Galaxies

Abstract A recent determination of the relationships between the X-ray luminosity of the ISM (L X) and the stellar and total mass for a sample of nearby early-type galaxies (ETGs) is used to investigate the origin of the hot gas, via a comparison with the results of hydrodynamical simulations of the ISM evolution for a large set of isolated ETGs. After the epoch of major galaxy formation (after z ≃ 2), the ISM is replenished by stellar mass losses and SN ejecta, at the rate predicted by stellar evolution, and is depleted by star formation; it is heated by the thermalization of stellar motions, SNe explosions, and the mechanical (from winds) and radiative AGN feedback. The models agree well with the observed relations, even for the largely different L X values at the same mass, thanks to the sensitivity of the gas flow to many galaxy properties; this holds for models including AGN feedback, and those without. Therefore, the mass input from the stellar population is able to account for a major part of the observed L X; and AGN feedback, while very important to maintain massive ETGs in a time-averaged quasi-steady state, keeping low star formation and the black hole mass, does not dramatically alter the gas content originating in stellar recycled material. These conclusions are based on theoretical predictions for the stellar population contributions in mass and energy, and on a self-consistent modeling of AGN feedback.

Age-stage, two-sex life table of Parapoynx crisonalis (Lepidoptera: Pyralidae) at different temperatures.

Parapoynx crisonalis is an important pest of many aquatic vegetables including water chestnuts. Understanding the relationship between temperature variations and the population growth rates of P. crisonalis is essential to predicting its population dynamics in water chestnuts ponds. These relationships were examined in this study based on the age-stage, two-sex life table of P. crisonalis developed in the laboratory at 21, 24, 27, 30, 33 and 36°C. The results showed that the values of Sxj (age-stage–specific survival rate), fxj (age-stage-specific fecundity), lx (age specific survival rate) and mx (age-specific fecundity) increased as the temperature rose from 21 to 27°C, then decreased from 30 to 36°C. Temperature also had a significant effect on the net reproductive rate (R0), gross reproductive rate (GRR), intrinsic rate of increase (r) and finite rate of increase (λ). The value of these parameters were at low levels at 21, 33, and 36°C. Further, the r value decreased as the temperature rose from 24 to 30°C, while the GRR reached its highest level at 27°C. The results indicated that optimal growth and development of P. crisonalis occurred at temperatures between 24°C to 30°C when compared to the lowest temperature (21°C) and higher temperatures of 33°C and 36°C.

EXPLORING X-RAY BINARY POPULATIONS IN COMPACT GROUP GALAXIES WITH CHANDRA

ABSTRACT We obtain total galaxy X-ray luminosities, L X, originating from individually detected point sources in a sample of 47 galaxies in 15 compact groups of galaxies (CGs). For the great majority of our galaxies, we find that the detected point sources most likely are local to their associated galaxy, and are thus extragalactic X-ray binaries (XRBs) or nuclear active galactic nuclei (AGNs). For spiral and irregular galaxies, we find that, after accounting for AGNs and nuclear sources, most CG galaxies are either within the ±1σ scatter of the Mineo et al. L X–star formation rate (SFR) correlation or have higher L X than predicted by this correlation for their SFR. We discuss how these “excesses” may be due to low metallicities and high interaction levels. For elliptical and S0 galaxies, after accounting for AGNs and nuclear sources, most CG galaxies are consistent with the Boroson et al. L X–stellar mass correlation for low-mass XRBs, with larger scatter, likely due to residual effects such as AGN activity or hot gas. Assuming non-nuclear sources are low- or high-mass XRBs, we use appropriate XRB luminosity functions to estimate the probability that stochastic effects can lead to such extreme L X values. We find that, although stochastic effects do not in general appear to be important, for some galaxies there is a significant probability that high L X values can be observed due to strong XRB variability.

Temperature-Dependent Fecundity and Life Table of the Fennel Aphid Hyadaphis foeniculi (Passerini) (Hemiptera: Aphididae).

Hyadaphis foeniculi (Passerini) (Hemiptera: Aphididae) is a cosmopolitan species and the main pest of fennel in northeastern Brazil. Understanding the relationship between temperature variations and the population growth rates of H. foeniculi is essential to predict the population dynamics of this aphid in the fennel crop. The aim of this study was to measure the effect of constant temperature on the adult prereproductive period and the life table fertility parameters (infinitesimal increase ratio (rm), gross reproduction rate (GRR), net reproduction rate (R0), finite increase ratio (λ), generation time (GT), the time required for the population to double in the number of individuals (DT), and the reproduction value (RVx)) of the fennel pest H. foeniculi. The values of lx (survival of nymphs at age x) increased as the temperature rose from 15 to 28°C and fell at 30°C, whereas mx (number of nymphs produced by each nymph of age x) increased from 15 to 25°C and fell at 28 and 30°C. The net reproduction rates (R0) of populations of H. foeniculi increased with temperature and ranged from 1.9 at 15°C to 12.23 at 28°C for each generation. The highest population increase occurred with the apterous aphids at 28°C. The rate of population increase per unit time (rm) (day) ranged from 0.0033 (15°C) to 0.1995 (28°C). The highest values of rm were recorded at temperatures of 28°C and 30°C. The rm values were a good fit to the models tested, with R2 > 0.91 and R2 adj > 0.88. The models tested (Davidson, Sharpe and DeMichele modified by Schoolfield et al., Logan et al., Lamb, and Briere et al.) were very good fits for the rm values observed, with R2 > 0.91 and R2 adj > 0.88. The only exception was the Davidson model. Of the parameters studied, the reproductive capacity was higher in the apterous aphids, with the unique exception of daily fecundity at 28°C, which was higher in the alate aphids of H. foeniculi. Parameters relating to the age-specific fertility table for H. foeniculi were heavily influenced by temperature, with the highest biotic potential and population growth capacity found at 34°C. Therefore, the results obtained in this study could be of practical significance for predicting outbreaks of fennel aphids and improving the management of this aphid in fennel crops.

Pre-main-sequence population in NGC 1893 region: X-ray properties

Continuing the attempt to understand the properties of the stellar content in the young cluster NGC 1893 we have carried out a comprehensive multi-wavelength study of the region. The present study focuses on the X-ray properties of T-Tauri Stars (TTSs) in the NGC 1893 region. We found a correlation between the X-ray luminosity, LX, and the stellar mass (in the range 0.2–2.0M⊙) of TTSs in the NGC 1893 region, similar to those reported in some other young clusters, however the value of the power-law slope obtained in the present study (∼0.9) for NGC 1893 is smaller than those (∼1.4–3.6) reported in the case of TMC, ONC, IC 348 and Chameleon star forming regions. However, the slope in the case of Class III sources (Weak line TTSs) is found to be comparable to that reported in the case of NGC 6611 (∼1.1). It is found that the presence of circumstellar disks has no influence on the X-ray emission. The X-ray luminosity for both CTTSs and WTTSs is found to decrease systematically with age (in the range ∼0.4–5Myr). The decrease of the X-ray luminosity of TTSs (slope ∼−0.6) in the case of NGC 1893 seems to be faster than observed in the case of other star-forming regions (slope −0.2 to −0.5). There is indication that the sources having relatively large NIR excess have relatively lower LX values. TTSs in NGC 1893 do not follow the well established X-ray activity – rotation relation as in the case of main-sequence stars.

Solidification/stabilization of metal polluted sediment of Krivaja river

The Krivaja River is the longest natural water body (109 km) that flows completely within the borders of Serbian province of Vojvodina. In the absence of national legislation, the sediment quality was assessed in accordance with the Dutch classification methodology. It was found that the river sediment is highly contaminated with copper and zinc (192 mg kg-1 and 1218 mg kg-1 respectively), and as such is an extreme risk to the environment and human health. The solidification/stabilization (S/S) treatment with local clay, that has high capacity of cation exchange 70.2 meq/100 g and specific surface area of 630 m2 g-1, was employed for remediation of the contaminated sediment. The sequential extraction procedure showed that the copper and zinc have medium risk for the environment, with the percentage in the carbonate fraction of 18 and 22% respectively. The results of sequential extraction are not in full agreement with the results of pseudo-total metal concentration in the sediment, which only confirms that the total metal concentration is not sufficient to define the real danger to the environment. Based on the pseudo-total metals concentration, the sediment is of Class 4 (Dutch standards). However, judging from the results of sequential extraction, the metals show medium risk. Obviously, these results have to be taken into account in the assessment of the sediment quality, remediation procedures and sediment disposal in general. After the treatment, the proportion of these two metals in the first fraction is significantly reduced (Cu less than 2%, Zn 10%) in most of samples. In order to determine the long-term behavior of S/S mixtures, leaching tests were conducted in accordance with semi-dynamic ANS diffusion test for 90 days. The results indicated that clay can effectively immobilize Cu and Zn: the cumulative leached fraction of copper in mixtures with clay was in the range from 0.001% (mixture with 80% clay) to 0.15% (mixture with 10% clay), and the cumulative leached fraction of zinc in the range of 0.06% (mixture with 80% clay) to 0.10% (mixture with 10% clay). The diffusion coefficients, ranging from 1.5?10-12 cm2s-1 to 3.7?10-14 cm2s-1, showed an effective immobilization of both metals which suggests that these metals are practically immobilized in S/S mixtures even if the level of clay is low. From the point of LX values, all S/S mixtures can be used for the controlled utilization, because the leaching indices ranged from 11.8 to 13.4 for both metals. In all clay and sediment mixtures the dominant leaching mechanism is diffusion (slope values of 0.35 to 0.60), which once again confirms the effectiveness of the applied treatment and can be expected that only a very small amount of contaminants would leach into the environment over time. Future research is heading in the direction of troubleshooting the accumulation of used natural adsorbent after treatment, the possibility of permanent disposal, its regeneration or the possibility of its application as construction material.

Cerebral tissue oxygenation measured by two different probes: challenges and interpretation

Cerebral tissue oxygenation (PbrO(2)) is most frequently monitored using a Licox CC1.SB system (LX, Integra Neuroscience, France) but recently a new probe--the Neurovent-PTO (NV)--was introduced by a different manufacturer (Raumedic, Germany). There are no prospective data on how these probes compare in clinical routine. We therefore compared both probes in comatose patients suffering from traumatic brain injury (TBI) or subarachnoid haemorrhage (SAH) during dynamic changes of inspirational oxygen fraction (FiO(2)) and mean arterial pressure (MAP). PbrO(2) in 11 patients was recorded continuously using an LX and NV probe placed side by side into the same cerebrovascular region. Once a steady baseline value was reached FiO(2) was increased by 20% for 10 min. Once the baseline values were re-established MAP was increased by 20 mmHg for 10 min. Evaluation was performed using a four-parameter logistic function and Bland-Altman analyses. PbrO(2) values of both probes differed significantly at all times. The LX probe reacted significantly faster to changes in FiO(2) and MAP. Limits of agreement ranged between -32.1 and 20.0 mmHg. Mean LX values were 6.1 mmHg lower than NV values. Since the examined patient cohort was rather small, this study's results are preliminary. However, they suggest that LX and NV probes measure different PbrO(2) values in routine monitoring as well as during phases of dynamic changes in FiO(2) and MAP. These data therefore do not support the view that both probes can be used interchangeably.

Correlation between the Results of Sequential Extraction and Effectiveness of Immobilization Treatment of Lead- and Cadmium-Contaminated Sediment

The assessment of the quality of sediment from the Great Backi Canal (Serbia), based on the pseudo-total lead (Pb) and cadmium (Cd) content according to the corresponding Dutch standards and Canadian guidelines, showed its severe contamination with these two metals. A microwave-assisted BCR (Community Bureau of Reference of the Commission of the European Union) sequential extraction procedure was employed to assess their potential mobility and risk to the aquatic environment. Comparison of the results of sequential extraction and different criteria for sediment quality assessment has led to somewhat contradictory conclusions. Namely, while the results of sequential extraction showed that Cd comes under the high-risk category, Pb shows low risk to the environment, despite its high pseudo-total content. The contaminated sediment, irrespective of the different speciation of Pb and Cd, was subjected to the same immobilization, stabilization/solidification (S/S) treatments using kaolinite, montmorillonite, kaolinite-quicklime, montmorillonite-quicklime, fly ash, zeolite, or zeolite-fly ash combination. Semi-dynamic leaching tests were conducted for Pb- and Cd-contaminated sediment in order to assess the long-term leaching behavior of these metals. In order to simulate “worst case” leaching conditions, the semi-dynamic leaching test was modified using 0.014 M acetic acid (pH = 3.25) and humic acid solutions (20 mg TOC l-1) as leachants instead of deionized water. The effectiveness of S/S treatment was evaluated by determining diffusion coefficients (De) and leachability indices (LX). The standard toxicity characteristic leaching procedure (TCLP) was applied to evaluate the extraction potential of Pb and Cd. A diffusion-based model was used to elucidate the controlling leaching mechanisms. Generally, the test results indicated that all applied S/S treatments were effective in immobilizing Pb and Cd, and the treated sediments may be considered acceptable for “controlled utilization” based on LX values, irrespective of their different availability in the untreated samples. In the majority of samples, the controlling leaching mechanism appeared to be diffusion, which indicates that a slow leaching of Cd and Pb could be expected when the above S/S agents were applied. The TCLP results showed that all S/S samples were nonhazardous.

Structure transition of two-dimensional hexagonal BN under large uniaxial strain

Using the first-principles method, we have studied the structure transition of two-dimensional hexagonal boron nitride (2D h-BN) under large uniaxial strain. The strain is applied by changing the values of Lx and Ly, which correspond to the lengths of primitive cell in the directions perpendicular and parallel to B—N bonds, respectively. For the large asymmetrical tensile strain perpendicular to B—N bonds, the rhombic structure is stable when Lx≤0.3388 nm. As the strain increases, the system transforms from the rhombic structure to a rectangular structure consisting of interlaced interacting BN chains, which becomes stable when Lx≥0.3488 nm. When the strain further increases, the system finally changes into the one comprised of isolated BN chains. For the 2D h-BN with large asymmetrical tensile strain distribution parallel to B—N bonds, there is no stable rectangular structure and the system becomes the one composed of isolated BN chains when Ly&gt;0.571 nm.

Two-dimensional symmetry breaking of fluid density distribution in closed nanoslits

Stable and metastable fluid density distributions (FDDs) in a closed nanoslit between two identical parallel solid walls have been identified on the basis of a nonlocal canonical ensemble density functional theory. Similar to Monte Carlo simulations, periodicity of the FDD in one of the lateral (parallel to the walls surfaces) directions, denoted as the x direction, was assumed. In the other lateral direction, y direction, the FDD was considered uniform. It was found that depending on the average fluid density in the slit, both uniform as well as nonuniform FDDs in the x direction can occur. The uniform FDDs are either symmetric or asymmetric about the middle plane between walls; the latter FDD being the consequence of a symmetry breaking across the slit. The nonuniform FDDs in the x direction occur either in the form of a bump on a thin liquid film covering the walls or as a liquid bridge between those walls and provide symmetry breaking in the x direction. For small and large average densities, the stable state is uniform in the x direction and is symmetric about the middle plane between walls. In the intermediate range of the average density and depending on the length L(x) of the FDD period, the stable state can be represented either by a FDD, which is uniform in the x direction and asymmetric about the middle of the slit (small values of L(x)), or by a bump- and bridgelike FDD for intermediate and large values of L(x), respectively. These results are in agreement with the Monte Carlo simulations performed earlier by other authors. Because the free energy of the stable state decreases monotonically with increasing L(x), one can conclude that the real period is very large (infinite) and that for the values of the parameters employed, a single bridge of finite length over the entire slit is generated.

Immobilization and leaching characteristics of arsenic from cement and/or lime solidified/stabilized spent adsorbent containing arsenic

Solidification/stabilization (S/S) of hazardous iron oxide coated cement (IOCC) spent adsorbent containing arsenic (As(III)) was investigated in the present study. Cement and lime-based S/S effectiveness was evaluated by performing semi-dynamic leach tests. The S/S effectiveness was evaluated by measuring effective diffusion coefficients ( D e) and leachability indices (LX). It was found that though cement or lime alone were efficient in preventing arsenic leaching ( D e being in range of 10 −10 to 10 −12 for all the matrices) from the solidified matrices, the best combination for arsenic containment in the matrix was obtained when a mixture of cement and lime was used. The LX values for all the matrices were higher than 10, suggesting that the S/S treated arsenic sludge are acceptable for “controlled utilization”. Calcite formation along with precipitation and conversion into non-soluble forms (calcium arsenite, calcium hydrogen arsenate hydrates, calcium hydrogen arsenates, etc.) were found to be the responsible mechanism for low leaching of arsenic from the solidified/stabilized samples. A linear relationship between cumulative fraction (CFR) of arsenic leached and square root of leach time ( R 2 ranging from 0.90 to 0.94) suggested that the diffusion is the responsible mechanism for arsenic leaching. Thus, cement and lime show effective containment of the As(III) within the matrix thus indicating S/S by cement and lime, which is also a low-cost option, as a suitable management option for the toxic As(III) sludge.

ChandraX-Ray Observations of Young Clusters. III. NGC 2264 and the Orion Flanking Fields

Chandra observations of solar-like pre-main sequence (PMS) stars in the Orion Flanking Fields (age ~1 Myr) and NGC 2264 (~3 Myr) are compared with the results of the COUP survey of similar objects in the ONC (~0.5 Myr). The correlations between log Lx and mass found for PMS stars on convective tracks in these clusters are consistent with the relationships found for the ONC, indicating little change in the median values of either log Lx or log Lx/Lbol during the first ~3-5 Myr of evolution down convective tracks. The fraction of stars with extreme values of Lx, more than 10 times higher than the average for a given Lbol or with log Lx/Lbol greater than the canonical saturation value of -2.9, is however larger by a factor of two in the younger ONC when compared with the Orion FF and NGC 2264. PMS stars in NGC 2264 on radiative tracks have Lx/Lbol values that are systematically lower by a factor of ~10 times than those found for stars of similar mass on convective tracks. The dramatic decrease in flux from convective to radiative phases of PMS evolution is likely related to major structural changes which influence the efficiency of magnetic field generation and thus the level of magnetic activity. As in the ONC, we find that stars with measured periods have, on average, higher X-ray luminosities. However, there is a wide range in Lx and Lx/Lbol for both periodic and non-periodic stars of similar mass. Among stars with measured periods, the level of X-ray emission does not correlate with the rotation rate. For this data set, we find no statistically significant correlation between X-ray flux and (a) the presence or absence of circumstellar accretion disks, or (b) disk accretion rates as assessed from ultraviolet excesses.