cssi/SciSciGPT-SciSciNet huggingface dataset:
Modeling of Spent - Acid Blockage Damage in Stimulated Gas Wells

Aqueous fluids introduced by different stimulation treatments cause water blockage in the near-wellbore region of wells. This water blockage acts the same as formation damage when the well is put back on production. One of the examples is when gas wells in carbonate reservoirs are acid-stimulated; the wormholes that propagate into the formations might be surrounded by a region of high water saturation created by the leakoff of spent acid. The spent-acid blockage damage could be severe, especially in lower permeability regions where capillary forces are relatively high. This paper presents a model that investigates the spent-acid damage in wormhole region of acid-stimulated gas wells. The phenomenon of spent-acid blockage was first investigated in the experimental study to identify the problem. A labscaled model was then developed to characterize the capillary pressure and relative permeability behavior by matching the results from the model to the experimental observation. We then extended the study to field-scale by approximating the wormhole as a long, slender half-ellipsoid centered in an ellipsoidal flow field. The simulations that focused on the displacement regime of spent acid recovery process were developed. These models were solved numerically to predict pressure behavior and spent acid distributions for the flow-back process. With the models, we studied the effects of several key factors, such as capillary pressure, relative permeability, and addition of additives, on the efficiency of spent acid recovery. The results show that common additives routinely added to acid systems may aid, or hinder, spent acid recovery, depending primarily on their effects on rock wettability. With the studies performed on the model developed, we provide recommendations for minimizing spent acid damage to gas well productivity.
Determining angular frequency from images of rotating objects via a generalized fast Fourier transform

In certain real-world applications, one needs to estimate the angular frequency of a spinning object. We consider the image processing problem of estimating this rate of rotation from a video of the object taken by a camera aligned with the axis of rotation. For many types of spinning objects, this problem can be addressed with existing techniques: simply register two consecutive video frames. We focus, however, on objects whose shape and intensity changes greatly from frame to frame, such as spinning plumes of plasma that emerge from a certain type of spacecraft thruster. To estimate the angular frequency of such objects, we introduce the Geometric Sum Transform (GST), a new rotation-based generalization of the discrete Fourier transform (DFT). Taking the GST of a given video produces a new sequence of images, the most coherent of which corresponds to the object's true rate of rotation. After formally demonstrating this fact, we provide a fast algorithm for computing the GST which generalizes the decimation-in-frequency approach for performing a Fast Fourier Transform (FFT). We further show that computing a GST is, in fact, mathematically equivalent to computing a system of DFTs, provided one can decompose each video frame in terms of an eigenbasis of a rotation operator. We conclude with numerical experimentation.
Sleep patterns in pediatric sickle cell disease.

Background Research examining sleep in children with sickle cell disease (SCD) has focused on the increased occurrence of specific sleep disorders (i.e., sleep-disordered breathing, hypoxemia, nocturnal enuresis), but no research exists describing general sleep behaviors of children with SCD. The purpose of the current study was to compare sleep patterns and sleep behaviors in children with SCD and healthy controls and examine the associations of demographic and disease factors with sleep in the SCD group. Procedure The Children's Sleep Habits Questionnaire was completed by parents of 4- to 10-year-old children with SCD (n = 54) and children attending well-care clinics in the same urban hospital (n = 52). Within the SCD group, demographic and disease factors [i.e., genotype, healthcare utilization, SCD complications, and socioeconomic status (SES)] were determined by medical chart review. Results Parents of children with SCD reported significantly more behaviors associated with night waking and sleep-disordered breathing than the control group. Within the SCD group, parasomnias were related to SES, enuresis, more severe genotypes, SCD complications, and healthcare utilization. Sleep-disordered breathing was also related to SES, enuresis, and SCD complications. Conclusions Results indicate the importance of routinely assessing sleep in children with SCD as they are more likely to exhibit disrupted sleep than children with similar demographic backgrounds. Given significantly higher rates of parent reported sleep-disordered breathing and night waking in this population, it is important to consider interventions to minimize disruptions to overnight sleep and improve daytime functioning for quality of life in children with SCD. Pediatr Blood Cancer. 2010;55:501–507. © 2010 Wiley-Liss, Inc.
Engagement quality review: insights from the academic literature

Purpose – The objective of this research is to identify areas where audit research can assist the Public Company Accounting Oversight Board (PCAOB) in its deliberation of the auditing standard on engagement quality (EQ) review required by the Sarbanes‐Oxley Act of 2002.Design/methodology/approach – The approach used in this paper is a review of the literature.Findings – The paper links academic research on EQ review to issues raised by the PCAOB. It also identifies questions for future research.Originality/value – The academic research reviewed in this paper provides important information to the PCAOB staff as it considers EQ review.
Chemical aging effects on the physio-mechanical properties of polyester and polypropylene geotextiles

Abstract The influence of groundwater chemistry on the durability of geotextiles is important for the design of municipal and hazardous waste landfills, geotextile reinforcement of slopes and subgrades, and earth retention systems. A series of tests are described in this paper, which explore the effects of various pH and saline environments on geotextiles, thus contributing to an improved understanding of durability as a basis for design. Accelerated aging was performed on polyester and polypropylane geotextiles at room temperature and temperatures elevated to 95°C for six months in saline ( ph∼8 ), strong alkaline (pH 10) and acidic (pH 3) media. Property changes as a result of aging were studied using tensile testing, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and intrinsic-viscosity (I.V.) measurements. Scanning electron microscopy (SEM) was employed to study changes in the surface topography of the fibers upon aging. An Arrhenius model was used to extrapolate results of this short term study to the actual lifetime of the geotextiles. Results indicate that polyester undergoes hydrolytic degradation under both acidic and alkaline conditions at and above the glass transition temperature, with the degradation being more severe under alkaline conditions. The polypropylene geotextile, on the other hand, was relatively inert to the pH conditions and showed no changes in strength. An increase in crystallinity in the initial period of aging was observed for both polyester and polypropylene. In polyester, this was due to preferential attack on the amorphous regions whereas in polypropylene this may be due to nucleation growth and lamellar thickening.
How effective are international criminal tribunals? An analysis of the ICTY and the ICTR

Abstract The International Criminal Tribunal for the Former Yugoslavia (ICTY) and the International Criminal Tribunal for Rwanda (ICTR) were established by the United Nations in 1993 and 1994 to apprehend and try individuals suspected of committing war crimes including genocide. The crimes that are prosecuted by these courts are the same, and the structure of the tribunals is also similar (indeed, they both share the same appellate court). However, the mandate of the ICTR is much more narrow and is limited both in terms of the period of time under investigation (one calendar year) as well as being limited to crimes that were committed only in Rwanda. Given the mandate and structure of these tribunals, many question their effectiveness. This article examines these tribunals and measures effectiveness by examining not only the number of indictments that have been handed down but the actual number of individuals apprehended. One of the criticisms of both tribunals is that the lack of success in apprehending ...
Fitness and Competitive Ability of an Azoxystrobin-Resistant G143A Mutant of Magnaporthe oryzae from Perennial Ryegrass

Development of azoxystrobin resistance in Magnaporthe oryzae from perennial ryegrass has been reported in certain locations in the United States, and possible development of resistance in additional areas is a major concern in the golf course industry. The study was undertaken to evaluate the relative fitness and competitive ability of a field-collected azoxystrobin-resistant G143A mutant by comparing it with a wild-type strain using detached perennial ryegrass blades. A fitness comparison experiment indicated that the disease severity of the wild-type strain was significantly higher than that of the mutant; however, the mutant produced greater secondary inoculum. When inoculated with three mixed populations of resistant and wild-type strains at different ratios, the production of conidia by the wild-type strain increased and that of the mutant decreased after infection occurred in all three populations tested. In an experiment on the effect of various fungicides on the population initially containing 5% of the mutant, preventive application of azoxystrobin allowed 5% of the mutant to dominate the population after the infection. However, other non-quinone outside inhibitor fungicides and mixtures of azoxystrobin with contact fungicides eliminated the entire mutant. This study demonstrates that the wild-type strain of M. oryzae has a competitive advantage over the mutant within the environment tested. Mixtures and alternations of fungicides with different modes of actions may prevent rapid build-up of resistance in the gray leaf spot pathosystem.
A discipline for a stage? A Shakespearean reflection on the research plot and performance of the Information Systems field

The different traditions of European and North American Information Systems research are highlighted and traditional means of measuring research quality (including citation patterns and journal impact factors) are questioned. Shakespearean metaphors are used to highlight these distinctions. The article concludes with a call for greater diversity and appreciation of alternative research traditions and cultures, and of the journals that publish such research.
Ineligible to Save? Asset Limits and the Saving Behavior of Welfare Recipients

ABSTRACT This article explores how asset limits used to determine eligibility for the Temporary Assistance for Needy Families (TANF) program influence the saving behavior of program participants. The qualitative evidence presented in this study serves to explain how asset limit policy may contribute to the low rate of savings and bank account ownership among the welfare population. From these conversations, it is clear that the existence of asset limits—or, just as importantly, the perception that these limits exist—negatively impacts the saving behavior of TANF recipients.
Genetic differentiation and diagnostic loci of Anopheles nuneztovari, An. trinkae, and An. rangeli (Diptera: Culicidae).

Samples of Anopheles rangeli Gabaldon, Cova Garcia & Lopez, An. trinkae Causey, and An. nuneztovari Gabaldon from Venezuela, Ecuador, Brazil, and Bolivia were analyzed for genetic variability at 24 enzyme loci. Estimates of genetic variability for An. rangeli and An. trinkae from Ecuador and for An. nuneztovari in Venezuela had the following ranges: 46–58% polymorphic loci, 1.7–2.0 (SEM = 0.1–0.3) mean number of alleles per locus, and 0.069–0.113 (SEM = 0.03–0.04) expected mean heterozygosity. Genetic variability estimates of An. rangeli from Bolivia were 20.8–29.2% polymorphic loci, 1.2–1.6 (SEM = 0.1– 0.2) mean number of alleles per locus, and 0.037–0.054 (SEM = 0.02–0.03) expected mean heterozygosity. The estimated genetic distance between An. rangeli and An. trinkae ranged from 0.149 to 0.197. The genetic distance between these 2 species and An. nuneztovari ranged from 0.319 to 0.440. Although there were allele frequency differences at some loci between samples of An. nuneztovari sampled from either side of the Andes Mountains in Venezuela, there were no diagnostic loci and the estimated genetic distance was only 0.023. Seven enzyme loci were diagnostic between An. nuneztovari and one or both of its sister species: Acon-2, Ao, Hk-1, Idh-2, Me, Pgi , and Pgm . The diagnostic loci Hk-1 and Acon-2 were not polymorphic in any species. An. rangeli and An. trinkae can be distinguished by the diagnostic loci Ao, Idh-2 , and Me-1 , and with a 97% probability by Pgm . Distance Wagner and unweighted pairgroup method with arithmetic averaging analyses support a close phylogenetic relationship between An. trinkae and An. rangeli .
Proton magnetic resonance absorption in ferrocene and its derivatives

Abstract Broad-line proton magnetic resonance absorption lines for derivatives of ferrocene have higher second moments than those observed for ferrocene. This is interpreted in terms of the slowing-down of the motion of cyclopentadienyl rings resulting from substitution in one or both rings. The trend is found to depend on the size of the substituent, and to increase with substitution in both rings. Such substitution favours a freezing of motion more readily than in ferrocene itself, which gives a somewhat narrow line (δH = 4 Gauss) even at 77°K. Anomalous narrowing of absorption lines, observed in some cases at temperatures below room temperature, is discussed. Results of theoretical calculations of second moments for the rigid and motional models of ferrocene are presented. A comparison of these with the experimental values places the concept of rotation of rings in ferrocene on a sound basis.
Extremum behavior of fluctuation amplitudes close to equilibrium

In a previous paper (Phys. Rev. E 1995, 52, 2198) we proposed that the fluctuation amplitudes of equilibrium systems are minimal relative to nearby dissipative nonequilibrium states. This behavior was found in nonequilibrium molecular dynamics calculations at fixed density and kinetic temperature. In this paper we examined this rule at fixed internal energy (microcanonical ensemble) and also for two-dimensional systems. We find that the extremum behavior remains valid despite the change in boundary conditions and system dimensionality.
Amino acid activation of amino acid transport system n early in primary cultures of rat hepatocytes

System N, a neutral amino acid transport system characterized in rat hepatocytes, shows significant changes in activity during the first 24 hr of primary culture (Weissbach, L., Handlogten, M.E., Christensen, H.N., and Kilberg, M.S. [1982] J. Biol. Chem. 257:12006-12011). Experiments presented in the present report demonstrate that during the first 12 hr of primary culture System N can be stimulated by individual amino acids in the culture medium by a cycloheximide-insensitive mechanism. This enhanced activity results from an elevation in the Vmax of the transport system, and the magnitude of the increase is related to the concentration of the amino acid in the culture medium. Nonsubstrates as well as substrates of System N are effective, and trans-stimulation does not appear to play a role in this phenomena. Transport by Systems ASC, Gly, and L is enhanced by the presence of amino acids in the culture medium, but these systems are significantly less sensitive than System N. The results suggest that amino acids act at a posttranslational step to activate System N activity.
ACS exams as an example of scholarship-based assessment in a discipline

The Examinations Institute of the American Chemical Society has been producing norm-referenced exams for over 75 years and these efforts are reviewed here. The process by which exam-writing committees produce these exams involves both the setting of the content and trial testing of items prior to establishing the released exam. Beyond this process, the Institute has engaged in research based on data derived from various tests.
Spectra and structure of small ring compounds. XXXVI. 2‐methyl‐1,3‐dioxolane; 2‐methyl‐1,3‐dioxolane‐d4; 2‐methyltetrahydrofuran; and methylcyclopentane

The infrared spectra of solid, liquid and gaseous 2-methyl-1,3-dioxolane, 2-methyl-1,3-dioxolane-d4, 2-methyltetrahydrofuran, and methylcyclopentane were recorded from 4000 to 33 cm−1. The Raman spectra were also recorded and depolarization values were measured for 2-methyl-1,3-dioxolane and methylcyclopentane. The fundamental vibrations of each compound have been assigned on the basis of group frequency correlations, isotopic shifts, and band intensities as well as depolarization values when applicable. The barrier hindering internal rotation of the methyl group has been calculated to be 3.5, 3.6, and 4.2 kcal mole−1 for 2-methyl-1,3-dioxolane, 2-methyltetrahydrofuran, and methylcyclopentane, respectively. The pseudorotational ring vibration was observed at 58 and 56 cm−1 for gaseous 2-methyl-1,3-dioxolane and 2-methyltetrahydrofuran, respectively. This implies a barrier to pseudorotation of the order of 1.3 kcal mole−1 for 2-methyl-1,3-dioxolane and 2-methyl-tetrahydrofuran. The pseudorotational mode could not be observed for methylcyclopentane, even at maximum pressure-path length condition.
Psychosocial issues in primary care of lesbian, gay, bisexual, and transgender youth

Lesbian, gay, bisexual, and transgender youth are at risk for a multitude of physical, emotional, and social health problems. During the past decade it has been well documented that these youth have higher-than-average rates of depression, suicide attempts, substance abuse, sexually transmitted diseases, school failure, family rejection, and homelessness. The focus of this article is to outline skills and strategies that can assist the health practitioner in creating an optimal health care experience for sexual minority youth. Models of individual and family adaptation, a clinical path, and a referral list are presented. Current health care delivery sites are examined, and recommendations are given for improvement of both practitioner skills and health care programs targeting these youth.
The synthetic juvenile hormone for control of Bovicola limbata on Angora goats.

In a preliminary field test, the Angoragoat biting louse, Bovicola limbala (Gervais), was controlled by making 3 spray applications of a 0.1% concentration of the synthetic juvenile hormone (methyl 10,11-epoxy-7-ethyl-3,11-dimethyl-2,6-tridecadienoate (mixed isomers)) 2 weeks apart. Lice counts declined rapidly after the 3rd application and averaged less than 2 lice per examined area (vs. 50–100 on untreated goats) for more than 16 weeks after initial treatment.
The Influence of Portfolio Characteristics and Investment Period on Investment Choice

Abstract Two experimental tests of the ability of potential investors to project return and risk information to a planning horizon found them to be decidedly more risk averse in creating portfolios on the basis of 1-year data than on the basis of data at a 10-year planning horizon. Three experimental tests of their ability to infer portfolio return and risk characteristics on the basis of the return and risk characteristics of the component investments found them to be insensitive to distributional characteristics in creating portfolios on the basis of both 1-year and 10-year data. Results are interpreted in terms of representativeness and anchoring-and-adjustment heuristics and a mental accounts decision rule. In addition, subjects preferred to obtain distributional information in the form of quantiles rather than moments and moments rather than probability density plots. We conclude that investors should be presented with a choice among the distributions of portfolios at the planning horizon and that these distributions should be characterized in simple, understandable terms.
Electronic Spectroscopy of the Al−CH4/CD4 Complex

The weakly bound Al−CH4 complex, and the fully deuterated version, Al−CD4, were prepared in a pulsed supersonic beam and probed with laser fluorescence excitation spectroscopy. Transitions to bound vibrational levels in electronic states correlating with the Al(5s,4d) + CH4/CD4 dissociation asymptotes have been observed. Resonance fluorescence from the excited levels could not be detected. Rather, these excited levels decay nonradiatively, and the excitation spectrum was obtained by monitoring emission from the lower Al atomic levels and AlH A → X chemiluminescence from formation of AlH(A1Π) within the excited complex. The band systems were dominated by progressions in the excited-state Al−CH4/CD4 van der Waals stretch vibrational mode. It was not possible to make unambiguous upper-state vibrational quantum number assignments, and lower bounds to excited-state binding energies were obtained. Band contour analysis of the AlH chemiluminescence spectra indicates that the excited AlH(A1Π) product is formed wi...
Multistranded Helix in Xanthan Polysaccharide

The extracellular polysaccharide xanthan is shown by electron microscopy to be an unbranched, probably double-stranded fiber 4 nanometers wide and 2 to 10 micrometers long when native. Denaturation yields a single strand only 2 nanometers wide and 0.3 to 1.8 micrometers long. Renatured xanthan shows short unraveled regions with two or three strands arranged in a right-handed twist.
RECOVERY AND CHARACTERIZATION OF TRANSGENIC PLANTS FROM TWO SPRING WHEAT CULTIVARS WITH LOW EMBRYOGENESIS EFFICIENCIES BY THE BOMBARDMENT OF ISOLATED SCUTELLA

Two commercial wheat cultivars with low embryogenesis efficiencies, AC Karma and Hy417, were transformed by the bombardment of isolated scutella with two gene constructs. Three AC Karma plants (433, 436, and 437) carrying plasmid pRC62 containing a gus:npt fusion gene, and one Hy417 plant (438) carrying plasmid pBARGUS containing a bar gene and a gusA gene were recovered and characterized. Presence of transgenes in T0 and T1 plants was confirmed by both PCR and Southern hybridization. Copy number of transgenes varied from one to six in these four plants. The inheritance of transgenes in the progeny was characterized. The gusA gene and its activity in AC Karma plant 436 and bar gene and its activity in Hy417 plant 438 segregated in the selfed T1 progeny in a Mendelian 3:1 ratio, but gusA gene and its activity in AC Karma plants 433 and 437 segregated in selfed T1 progeny in a non-Mendelian 1:1 ratio. The gusA activity in all three AC Karma plants was stably transmitted to selfed T2 or T3 progenies. The levels of gusA and nptII activities in nine T1 plants from AC Karma plant 437 were also determined. A GusA fluorometric assay indicated that gusA activity in the nine T1 plants increased by 2.5–7.2-fold compared with the nontransformed control, while and NptII ELISA assay detected nptII activity only in two of the nine T1 plants, suggesting the nptII gene was silenced in the other seven T1 plants.
Effect of capillary heterogeneity on buoyant plumes: A new local trapping mechanism

Abstract CO2 can be immobilized in an aquifer as a residual phase trapped by capillary forces. The “inject low and let rise” strategy of storing CO2 in d eep saline aquifers is one method to maximize residual trapping. The more uniform the saturation front during upward movement of CO2, the greater the amount of CO2 trapped in this form. Previous studies suggest that capillary pressure i s a secondary influence on the CO2 plume, and that the permeability field governs the major features of the rising plume. In this work we show that sp atially varying capillary entry pressure can cause qualitatively different plume behavior. To illustrate the behavior, we si mulate buoyancy-driven migration when supercritical CO2 is placed below brine in a heterogeneous domain. After generating geostatistical realizations of permeability, we apply the Leverett J -function so that each grid block has a drainage curve ( p c vs S w ) physically consistent with its permeability. The behavior of the displacement front depends strongly on the correlation structure of the heterogeneity and upon the magnitude of entry pressure. In a relatively homogeneous domain, capillar ity is a second-order effect. It damps the tendency toward channeling of the rising CO2 front and increases the uniformity of the plume. As the heterogeneity of the aquifer increases, capillarity begins to dominate buoyancy. Regions with smaller permeability, through which single-phase flow would readily occur, can completely block rising CO2, simply because the capillary entry pressure in these regions is somewhat larger than in neighboring regions. These local capillary barriers prevent CO2 from rising and cause it to mov e laterally. The disruption can be so extreme that above-residual saturations of CO2 accumulate below these barriers. These local accumulations can remain undisturbed when the top seal of the aquifer is breached. Thus we distinguish them as a new mode of CO2 trapping, dubbed “local capillary trapping”. Overall, the displacement front is much less uniform in heterog eneous domains. Despite the nonuniformity, the extent of dissolution trapping remains significant, much more than would be expected considering the ramified structure of the displacement front. T he reduction in residual phase trapping is balanced by an increase in local capillary trapping. Thus the extent of immobilization is similar to that found in previous works.
Suppression of the D'yakonov-Perel' spin relaxation mechanism for all spin components in [111] zincblende quantum wells

We apply the D'yakonov-Perel' (DP) formalism to [111]-grown zinc blende quantum wells (QW's) to compute the spin lifetimes of electrons in the two-dimensional electron gas. We account for both bulk and structural inversion asymmetry (Rashba) effects. We see that, under certain conditions, the spin splitting vanishes to first order in $k$, which effectively suppresses the DP spin relaxation mechanism for all three spin components. We predict extended spin lifetimes as a result, giving rise to the possibility of enhanced spin storage. We also study [110]-grown QW's, where the effect of structural inversion asymmetry is to augment the spin relaxation rate of the component perpendicular to the well. We derive analytical expressions for the spin lifetime tensor and its proper axes, and see that they are dependent on the relative magnitude of the BIA- and SIA-induced splittings.
Weaver ants: social establishment and maintenance of territory

Workers of the African weaver ant Oecophylla longinoda recruit nestmates to previously unoccupied space by means of odor trails laid from the rectal gland, a hitherto unrecognized musculated organ located at the rear of the rectal sac. When enemy ants and other intruders are encountered on the territory, the Oecophylla assemble nestmates into small resting clusters by dispensing an attractant-arrestant pheromone from the sternal gland, a second newly discovered organ located on the last abdominal sternite. Under prolonged stress, additional forces are recruited to the combat area with the aid of the rectal-gland trail substance.
Legionella pneumophila cell envelope: Permeability to hydrophobic molecules

Legionella pneumophila is sensitive to a number of toxic hydrophobic compounds. Suspensions of cells bound large amounts of the dye crystal violet, and disk agar diffusion assays confirmed the marked sensitivity to this compound. Fatty acids were also inhibitory to the growth ofL. pneumophila in liquid media, and growth inhibition increased with increasing chain length to a maximum with myristic acid. Oxygen uptake by respiring cells was inhibited by similar concentrations of fatty acids.L. pneumophila was also sensitive to low concentrations of progesterone. These results indicated thatL. pneumophila has an outer membrane with unusual permeability to hydrophobic compounds. This characteristic was accompanied by a measurable cell surface hydrophobicity as determined by adherence of the bacterium to the hydrocarbon hexadecane.
CFD Simulation of Single Step and Double Notched Tooth for Labyrinth Seals

A variant “Stepped Double Notched Tooth” for conventional sharp teeth of a labyrinth seal has been proposed and investigated by three-dimensional CFD numerical modeling of the flow field. The purpose is to reduce total leakage through the seal. The tooth is numerically tested with both solid and honeycomb lands. CFD assumptions and analysis were validated by comparison with leakage data from stationary labyrinth seal experiments conducted by Stocker [1]. The baseline model considered for comparison study consists of the conventional straight-through four sharp knife shaped teeth in combination with solid and honeycomb land. The variant tooth is also straight having a sharp tip but has a stepped inclined notch opposing the flow at both sides of the tip. CFD analyses revealed that this double notched tooth reduces seal leakage by ∼10.7% when used with solid land and ∼12.5% when used with honeycomb land compared to a conventional baseline tooth.Copyright © 2014 by ASME
A blocking model of membrane filtration

Abstract A model of membrane filtration based on particle retention within membrane media is proposed. The model provides a realistic description of filtration behavior and is based on current theories of deep bed filtration. Tentative correlations of model parameters are proposed and suggestions to establish more complete correlations are offered.
Use of Portable Oxygen and Carbon Dioxide Detectors to Screen Soil Gas for Subsurface Gasoline Contamination

The field screening of soil gas CO2 and O2 using portable instruments is shown to be useful for indirectly detecting and delineating subsurface gasoline contamination. Shallow (< 50 cm) soil gas surveys performed at a site of subsurface gasoline contamination in Connecticut indicated a good correlation between elevated CO2, depleted O2, and total hydrocarbon vapor anomalies. CO2 and O2 anomalies were also found to be spatially coincident with the area of known subsurface gasoline leakage. Soil gas CO2 levels ranged from 0.2 to 18.7 volume percent, whereas O2 levels ranged from 20.8 to 0.5 volume percent. The gases exhibited a nearly constant inverse correlation except near the source of contamination. In this area, CO2 generation from anaerobic degradation of hydrocarbons likely caused a decrease in the observed CO2 and O2 correlation. This suggests that the ratio of soil gas CO2 to O2 may be useful to delineate aerobic and anaerobic degradation zones, the latter being in the vicinity of highly contaminated areas. Periodic sampling of seven permanent soil gas probes over a 17-month period indicated significant seasonal variations in CO2 and O2. When the soil was warmest during the summer, the CO2 reached a maximum and O2 reached a minimum. The opposite was observed during the winter when the soil achieved its minimum temperature. These observations most likely reflect changes in microbial acitivity in response to subsurface temperature variations. Further, hydrocarbon vapor levels were observed to decrease by several orders of magnitude to nondetectable levels during the winter months. Although CO2 and O2 anomalies were also diminished during the winter months, they were still readily detectable. These observations indicate that soil gas surveying for subsurface gasoline leakage may be enhanced by monitoring CO2 and O2.
Respiratory depressant and skeletal muscle relaxant effects of low-dose pancuronium bromide in spontaneously breathing, isoflurane-anesthetized dogs.

Objective—To assess and compare the respiratory depressant and skeletal muscle relaxant effects of two low doses of a nondepolarizing neuromuscular blocker, pancuronium bromide. To determine if a “low dose” of pancuronium bromide can produce selective skeletal muscle relaxation in extraocular muscles sufficient to perform intraocular surgery while sparing or minimizing depression of muscles of ventilation. Study Design—Blinded, randomized crossover, placebo controlled study. Animals—Six healthy, adult mongrel dogs weighing 20.8 ±1.9 kg. Methods—Spontaneously breathing, isoflurane-anesthetized dogs received 0.02 mg/kg pancuronium bromide, intravenously (IV), (high dose [HD]), 0.01 mg/kg pancuronium bromide, IV, (low dose [LD]), or saline placebo IV in a blinded, randomized crossover study. Indices of patient ventilation including tidal volume (Vt), respiratory rate (RR), and minute ventilation (VE) were recorded throughout the study period. Serial arterial blood gas analyses were performed at timed intervals. Neuromuscular blockade of skeletal muscle was assessed at timed intervals with train-of-four stimulus/response ratios. Eye position scores, based on the degree of ocular rotation from a neutral gaze axis, were assigned by an ophthalmologist who was blinded to the treatment given. Results—Vt and VE in HD dogs decreased by 82% from baseline after administration of pancuronium bromide. Similarly, Vt and VE in LD dogs decreased 40% and 55%, respectively. Decreased ventilation in HD dogs corresponded with significant (P< .05) neuromuscular blockade, as indicated by train-of-four ratio less than 75% between 0 and 60 minutes. Eye position scores in HD and LD dogs were suitable for intraocular surgery between 0 and 60 minutes. Eye position scores in five of six control dogs were unsuitable for intraocular surgery at any time period. Conclusions—LD dogs experienced only transient, mild to moderate respiratory depression compared with HD dogs, which experienced prolonged, moderate to severe respiratory depression. Both LD and HD dogs acquired and maintained eye position scores suitable for intraocular surgery between 0 to 60 minutes. A “low dose” of pancuronium bromide, which would provide adequate extraocular muscle relaxation while minimizing ventilatory depression, was not identified. Clinical Relevance—All patients receiving any dose of neuromuscular blocking agents should be closely monitored and receive ventilatory assistance as needed.
Trade-offs associated with axillary lymph node dissection with breast irradiation versus breast irradiation alone in patients with a positive sentinel node in relation to the risk of non-sentinel node involvement: implications of ACOSOG Z0011.

Recent data suggest that axillary lymph node dissection (ALND) may be unnecessary for patients with positive sentinel lymph node biopsy (SLNB) receiving whole-breast irradiation (ACOSOG Z0011). The purpose of this study was to use decision analysis with simulated patients to determine subgroups with positive SLNB who may still benefit from ALND. We performed a decision analysis simulating axillary recurrence (ALR) risk, lymphedema, and quality of life following breast-conserving surgery (BCS) with positive SLNB and either completion ALND and whole-breast radiation (ALND + BRT) or breast radiation (BRT) alone. Simulated patients were divided into two risk groups based on the likelihood of disease in non-sentinel axillary nodes after positive SLNB: those with risk 30–60 % (“high-risk”) and those with risk under 30 % (“low-risk,” similar to average Z0011 patients). In simulated patients aged 55, BRT alone resulted in 1 month of additional QALE in the low-risk group versus ALND + BRT, while ALND + BRT resulted in 9.7 months of additional QALE in the high-risk group versus BRT alone. Overall survival was similar at 5 years in this simulation with either treatment in both groups, but ALND + BRT was superior to BRT alone at 20 years in the high-risk group (42 vs. 38 %). In the low-risk group, BRT alone is preferable unless ALR risk with BRT is greater than 1.6 % or lymphedema risk with ALND is under 10 %. Patients eligible for Z0011 but at a higher risk of residual nodal disease following BCS and positive SLNB may benefit from ALND + BRT, rather than BRT alone.
Novel toxin assays implicate Mycoplasma pneumoniae in prolonged ventilator course and hypoxemia

Background Community-acquired respiratory distress syndrome (CARDS) toxin is a unique Mycoplasma pneumoniae virulence factor. Molecular assays targeting this toxin are more sensitive than existing diagnostics, but these assays have not been used to investigate the role of M pneumoniae as a nosocomial infection in critical illness. We sought to determine the incidence of M pneumoniae among mechanically ventilated subjects using these novel assays and to investigate the impact of this pathogen on pulmonary outcomes. Methods We conducted a prospective observational study enrolling subjects with suspected ventilator-associated pneumonia (VAP) undergoing BAL in the surgical trauma ICU at a level I trauma center. Lavage fluid and serum samples were tested for M pneumoniae using assays to detect CARDS toxin gene sequences, protein, or antitoxin antibodies. Results We collected samples from 37 subjects, with 41% (15 of 37) testing positive using these assays. The positive and negative groups did not differ significantly in baseline demographic characteristics, including age, sex, injury severity, or number of ventilator days before bronchoscopy. The positive group had significantly fewer ventilator-free days (P = .04) and lower average oxygenation (P = .02). These differences were most pronounced among subjects with ARDS. Conclusions Evidence is provided that M pneumoniae is present in a substantial number of subjects with suspected VAP. Subjects testing positive experience a significantly longer ventilator course and worse oxygenation compared with subjects testing negative.
Diffraction, refraction, and interference phenomena in heavy-ion transfer reactions

The forward-angle oscillations recently observed in heavy-ion transfer reactions are explained as the Young interference pattern of a refractive two-slit "optical system" in $l$ space, and a new phenomenon is predicted.
Synthesis of syringolide 1 ketals and esters for receptor studies

Abstract The syringolides, specified by avirulence gene D from Pseudomonas syringae, elicit a disease defense reaction only in soybean cultivars carrying the Rpg4 disease resistance gene. In order to identify structural features important for elicitor activity and construct highly labelled elicitor-active probes, several syringolide esters and ketals were synthesized. Alteration of the C-3 hemiketal group of syringolide 1 abolished elicitor activity, but ester derivatives based on the C-4′ hydroxy group all retained activity. [125I]4′-(2-iodo-3,4,5-trimethoxyphenylacetyl) syringolide 1 was prepared for receptor studies.
High-temperature crystal chemistry of phenakite (Be 2 SiO 4 ) and chrysoberyl (BeAl 2 O 4 )

Thermal expansion and high-temperature crystal structures of phenakite and chrysoberyl have been determined by x-ray methods at several temperatures to 690° C. Phenakite (hexagonal, space groupR $$\bar 3$$ ) has slightly anisotropic thermal expansion; average expansions between 25 and 690° C perpendicular and parallel to thec axis are α⊥=5.2×10−6 °C−1 and α∥=6.4×10−6 °C−1, respectively. The unit cell volume of phenakite over this temperature range is given by the polynomial expression:V = 1102.9(2) + 0.010(2)T + 1.1(3) × 10-5 T 2. Chrysoberyl (orthorhombic, space groupPbnm) has nearly isotropic thermal expansion, with maximum expansivity 8.5×10−6 °C−1 parallel to theb axis, and minimum expansivity 7.4×10−6 °C−1 parallel toa. Thec axis expansivity is 8.3×10−6 °C−1. Chrysoberyl volume between 25° and 690° C may be represented by:V = 227.1(2) + 0.003(1)T + 4(2) × 10-6 T 2. The thermal expansion of beryllium, aluminum, and silicon cation coordination polyhedra in phenakite and chrysoberyl are similar to values found in previous studies of minerals in the BeO-Al2O3-SiO2 system. High-temperature structure studies of bromellite (BeO), beryl (Be3Al2Si6O18), phenakite and chrysoberyl all have beryllium tetrahedra that display the same near-zero expansion at room temperature, but increasing expansion at higher temperatures.
Reaction times in a task analogous to “same”-“different” judgment

Subjects responded “yes” if two equal-length strings of letters contained a common letter in a common position; otherwise they responded “no.” Thus, the task was to judge whether all or not all of the letters in one string differed from the letter occupying the corresponding position in the other string. Conversely, in “same”-“different” judgment, the task is to judge whether all or not all of the letters in one string match the corresponding letter in the other string. Thus, common-letter judgment and “same”-“different” judgment are symmetrically related with “no” analogous to “same” and “yes” analogous to “different.” The response “same” is often faster than the response “different.” However, in the common-letter task, “no” was slower than “yes.” More specifically, both the “yes” and “no” reaction times were consistent with a serial self-terminating search. This is precisely what would be expected from Bamber’s (1969) two-process model.
REDUCTION OF ACETYLENE AND NITROGEN BY FIELD-GROWN SOYBEANS

Summary Acetylene reduction by soybean nodules started without a lag and remained linear with time for about 80 minutes. There was no apparent injury to nodules from evacuation. Rates of reduction of acetylene increased with increasing pO2 to 1 atm; respiration did not seriously deplete the available O2 from bottles in which nodules occupied less than 20% of the volume of the bottles. Reduction of acetylene decreased markedly in nodules soaked in water. About 0.2 atm acetylene supported the most rapid reduction of acetylene, and nodules 3–5 mm in diameter were most active. Intact soybean plants, nodulated roots and detached nodules fixed nitrogen at relative rates of approximately 100/46/23. The soybean plants exhibited a diurnal cycle of acetylene reduction dependent upon light intensity and air temperature. The observed ratio of acetylene reduced to N2 reduced was approximately 2.0 rather than the often assumed theoretical value of 3.0. There was a dramatic difference among soybean varieties in the date of onset and termination of acetylene reduction. Acetylene reduction was most vigorous in plants inoculated with a mixture of effective strains of Rhizobium japonicum.
Haydn, Meter, and Listening in Transition

In recent years, music theorists and analysts have devoted a great deal of attention to the phenomenon of hypermeter, drawing some of their most representative examples from the late works of Haydn. Although this recent trend in analysis has shed much light on Haydn’s music, it has left questions of history distinct from the mode of listening it engages. This article argues that the way we understand conceptualizations of listening and aesthetic experience can greatly inform the way that we understand hypermeter and the question of style in history. Drawing on eighteenth-century theories of music and literature, it recontextualizes Haydn’s hypermetric style with respect to a larger world of aesthetic experience.
Phytophotolysis of Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in leaves of Reed Canary Grass

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) was degraded in reed canary grass leaves exposed to simulated sunlight to primary products nitrous oxide and 4-nitro-2,4-diazabutanal. This is the first time that 4-nitro-2,4-diazabutanal, a potentially toxic degradate, has been measured in plant tissues following phytotransformation of RDX. These compounds, along with nitrite and formaldehyde, were also detected in aqueous RDX systems exposed to the same simulated sunlight. Results showed that the initial products of RDX photodegradation in translucent plant tissues were similar to products formed from aqueous photolysis of RDX. Combustion analysis of leaves following 14C-RDX uptake and subsequent light exposure revealed the presence of tissue-bound material that could not be extracted with acetonitrile. No detectable formaldehyde was emitted from the leaves. The detection of similar RDX degradation products in both aqueous and plant-based systems suggests that RDX may be initially transformed by similar mechanisms in both systems. Direct photolysis of RDX via ultraviolet irradiation passing into the leaves is hypothesized to be responsible for the observed transformations. In addition, membrane-bound "trap chlorophyll" in the chloroplasts may shuttle electrons to RDX as an indirect photolysis transformation mechanism. Results from this study indicate that reed canary grass facilitates photochemical degradation of RDX, and this mechanism should be considered along with more established phytoremediation processes when assessing the fate of contaminants in plant tissues. Plant-mediated phototransformation of xenobiotic compounds is a process that may be termed "phytophotolysis".
Secondary ion mass spectrometry and its relation to high-energy ion beam analysis techniques

Abstract A critical look is taken at the analytical technique of secondary ion mass spectrometry (SIMS), to compare it with the high-energy analytical techniques of Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). It is found that the strengths and weaknesses of SIMS dovetail nicely with those of RBS and NRA, forming a complementary relationship. The strengths of SIMS include: high sensitivity, good depth resolution, ability to detect all elements, ability to differentiate between isotopes, and good elemental specificity. Weaknesses of SIMS arise from variation in elemental sensitivity, surface topography modification, and ion-induced atomic mixing effects.
Effects of dietary sinigrin or indole-3-carbinol on O6-methylguanine-DNA-transmethylase activity and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced DNA methylation and tumorigenicity in F344 rats

The effects of dietary sinigrin and indole-3-carbinol (I3C) on DNA methylation and O6-methylguanine--DNA-transmethylase activity, factors which may be of importance in the induction of tumorigenicity by the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), were investigated. Additionally, the effects of dietary sinigrin on NNK tumorigenicity were assessed in a two-year bioassay in F344 rats. DNA methylation in target tissues of NNK tumorigenesis was examined in F344 rats administered [3H-CH3]NNK (0.6 mg/kg, four doses) s.c. and fed control or experimental diets for two weeks. Dietary sinigrin at a concentration of 3 mumol/g diet decreased 7-methylguanine formation in hepatic DNA, but had no effect on 7-methylguanine levels of lung or nasal mucosa DNA. Dietary I3C at a concentration of 30 mumol/g diet increased 7-methylguanine levels in hepatic DNA, but decreased DNA methylation in lung and nasal mucosa. No effects on O6-methylguanine--DNA-transmethylase activity were observed in tissue extracts derived from the livers, lungs and nasal mucosae of rats fed diets containing sinigrin or I3C. These results suggested that dietary sinigrin might reduce the incidence of NNK-induced hepatic tumors with no effect on NNK tumorigenesis of the lung and nasal cavity, whereas I3C might increase hepatic tumor incidence and reduce NNK tumorigenesis of the lung and nasal cavity. The bioassay results showed that dietary sinigrin had no effect on NNK tumorigenesis in these target tissues. However, dietary sinigrin plus NNK resulted in a significant incidence of pancreatic tumors, a rare occurrence in F344 rats. While the results from DNA methylation studies are in agreement with the bioassay data for lung and nasal cavity, the absence of any inhibitory effect of dietary sinigrin on NNK hepatic tumorigenesis indicates that factors other than DNA methylation and O6-methylguanine repair should be considered in assessing the effects of dietary compounds on NNK hepatic tumorigenesis. The contrary effects on NNK-induced hepatic DNA methylation by sinigrin and I3C, two major components of cruciferous vegetables, demonstrate the complexities of dietary modulation of carcinogenesis.