Dilution Measurements Research Articles

Thermodynamics of synthesis and separation performance of Interfacially polymerized “loose” reverse osmosis membrane: Benchmarking for greywater treatment

• Interfacially polymerized hollow fiber “Loose Reverse Osmosis” LRO membranes. • LRO capable of treating greywater and removal of TDS. • Energetic performance of LRO close to thermodynamic limits of separation. • LRO potential to be positioned as a new class of membranes for low TDS streams. Greywater recycling is a promising alternative to purify a relatively clean stream at a lower energy penalty. In the present work, greywater treatment through “loose” thin-film composite (TFC) reverse osmosis (RO) membranes have been attempted. Polymer interactions between cellulose acetate (CA) and additives like polyvinyl pyrrolidone (PVP) and polyethylene glycol (PEG) have been studied along with their miscibilities in n-methyl pyrrolidone (NMP) solvent. The compatibility was understood through dilute solution viscometry measurements, and ternary phase diagrams, the miscibilities/immiscibilities of the CA-PVP, CA-PEG blends in NMP was explored. It was found that CA-PVP yielded less stable solutions than CA-PEG. This was reflected in their membrane morphologies, permeability, and porosities. Thus, two membranes were chosen, one of the highest permeability and one of the lowest permeability and underwent interfacial polymerization to yield “Loose” TFC – RO membranes. These were subjected to synthetic TDS (Total Dissolved Solids) levels (500–1000 ppm) and real-life greywater streams. The energetics of separation at bench scale against the theoretical thermodynamic analysis of free energy was calculated. For synthetic streams, it was observed that experimental energy of separation was found closer to the theoretical minimum. Thus, it was concluded that with proper pre-treatment strategies, real-life greywater could be treated in an energy-efficient way.

Effect of temperature and volume alterations on accuracy and trending of transpulmonary ultrasound dilution measurements

Effect of temperature and volume alterations on accuracy and trending of transpulmonary ultrasound dilution measurements

High abundance of the colistin resistance gene mcr-1 in chicken gut-bacteria in Bangladesh

Colistin is considered a last-resort reserved drug for the treatment of critical human infections by Gram-negative bacteria. Phenotypic colistin-resistance is strongly associated with plasmid-mediated mobile colistin resistance (mcr) genes. The mcr-bearing Enterobacteriaceae have been detected in many countries from environments, animals, and humans. This study investigated phenotypic colistin-resistance and the distribution of mcr-1, mcr-2, mcr-3, mcr-4, and mcr-5 genes in chicken-gut bacteria in Bangladesh. Bacteria were isolated from poultry- and native-chicken droppings, and their susceptibilities to colistin were determined by agar dilution and E-test minimal inhibitory concentration (MIC) measurements. Multiplex polymerase chain reactions detected mcr-1 to mcr-5 genes. Overall, 61.7% (92/149) of the isolates showed colistin resistance by agar dilution assessment (MIC > 2.0 μg/mL). The phenotypic resistance was observed considerably higher in poultry-chicken isolates (64.6%, 64/99) than in native-chicken isolates (56%, 28/50; p = 0.373). All the resistant isolates showed MIC levels between > 2 and > 128 μg/mL. The mcr-genes (mcr-1and mcr-2 combined) were detected more in poultry gut bacteria (36.4%) than native-chicken isolates (20%, p = 0.06). Despite bacteria sources, mcr-genes appeared to be significantly associated with phenotypic colistin-resistance phenomena (p < 0.001). Prior colistin usage led to a substantial increase in the proportion of bacteria with mcr-genes and phenotypic resistance (p < 0.001).

Application of regression methods to solve general isotope dilution measurement equations

Isotope dilution is among the most accurate quantitation approaches in chemical analysis. This calibration method is often employed using a plurality of mathematical formulations. While most analysts find the calibration curve approach most appealing, there is a lack of rigorous general procedures involving calibration curves in isotope dilution and analysts resort to empirical polynomial calibration functions. In this contribution we discuss the adoption of regression analysis, commonly known as least squares methods, to solve isotope dilution equations of varied complexity. This manuscript introduces general regression-based methods to isotope dilution applicable to all known variants of classical isotope dilution known to date, including the fusion of the isotope dilution and standard additions methods.

A highly‑enriched 244Pu reference material for nuclear safeguards and nuclear forensics measurements.

A highly-enriched 244Pu isotope dilution reference material has been prepared and characterized for metrologically traceable measurements of very small quantities of plutonium. The amount of plutonium in samples associated with nuclear safeguards and nuclear forensic measurements can be significantly less than 1 ng. Accordingly, the ability to quantify the amount and isotopic composition of plutonium from a single mass-spectrometric analysis is particularly desirable. The highly-enriched 244Pu reference material, described here, will minimize the magnitude of spike corrections necessary to obtain accurate information on plutonium isotopic composition from isotope dilution measurements.

A study of volatility by composition, heating, and dilution measurements of secondary organic aerosol from 1,3,5-trimethylbenzene

Abstract. Studies of the volatility distribution of secondary organic aerosol (SOA) from aromatic compounds are limited compared with SOA from biogenic monoterpenes. In this study, the volatility distribution was investigated by composition, heating, and dilution measurements for SOA formed from the photooxidation of 1,3,5-trimethylbenzene in the presence of NOx. Composition studies revealed that highly oxygenated monomers (C9H14Ox, x = 4–7) and dimers (C18H26Ox, x = 8–12) are the major products in SOA particles. Highly oxygenated molecules (HOMs) with five or more oxygens were formed during photochemical aging, whereas dimers degraded during photochemical aging. HOMs with five or more oxygens may be produced from the photooxidation of phenol-type gaseous products, whereas dimers in the particle phase may be photolyzed to smaller molecules during photochemical aging. The results of composition, heating, and dilution measurements showed that fresh SOA that formed from 1,3,5-trimethylbenzene (TMB) photooxidation includes low-volatility compounds with &lt;1 µg m−3 saturation concentrations, which are attributed to dimers. Similar results were reported for α-pinene SOA in previous studies. Low-volatility compounds with &lt;1 µg m−3 saturation concentrations are not included in the volatility distributions employed in the standard volatility basis-set (VBS) approach. Improvements in the organic aerosol model will be necessary for the study of anthropogenic SOA as well as biogenic SOA.

A single Thaumarchaeon drives nitrification in deep oligotrophic Lake Constance.

Ammonia released during organic matter mineralization is converted during nitrification to nitrate. We followed spatiotemporal dynamics of the nitrifying microbial community in deep oligotrophic Lake Constance. Depth-dependent decrease of total ammonium (0.01-0.84 μM) indicated the hypolimnion as the major place of nitrification with 15 N-isotope dilution measurements indicating a threefold daily turnover of hypolimnetic total ammonium. This was mirrored by a strong increase of ammonia-oxidizing Thaumarchaeota towards the hypolimnion (13%-21% of bacterioplankton) throughout spring to autumn as revealed by amplicon sequencing and quantitative polymerase chain reaction. Ammonia-oxidizing bacteria were typically two orders of magnitude less abundant and completely ammonia-oxidizing (comammox) bacteria were not detected. Both, 16S rRNA gene and amoA (encoding ammonia monooxygenase subunit B) analyses identified only one major species-level operational taxonomic unit (OTU) of Thaumarchaeota (99% of all ammonia oxidizers in the hypolimnion), which was affiliated to Nitrosopumilus spp. The relative abundance distribution of the single Thaumarchaeon strongly correlated to an equally abundant Chloroflexi clade CL500-11 OTU and a Nitrospira OTU that was one order of magnitude less abundant. The latter dominated among recognized nitrite oxidizers. This extremely low diversity of nitrifiers shows how vulnerable the ecosystem process of nitrification may be in Lake Constance as Central Europe's third largest lake.

Effect of Shallowness on Dilution of Unidirectional Diffusers

AbstractThe effect of receiving water depth on the dilution of a unidirectional diffuser discharging dense effluent in quiescent conditions is analyzed. Dilution measurements from previous studies ...

Lithium-Ion Transport and Cycling Characteristics of Fluorinated Electrolytes

Electrical energy is ubiquitous in the modern world, and in order to continue pushing boundaries on consumer wearables, electric vehicles, and grid storage, secondary lithium-based rechargeable batteries need to be enhanced. The performance of binary electrolytes is governed by the electrolyte thermodynamic factor and three transport properties: conductivity, salt diffusion coefficient, and transference number. Rigorous methods for measuring conductivity and the salt diffusion coefficient are well established in literature. NMR and the steady-state current method are often used to measure the transference number, but are predicated on the dilute solution assumption and do not fully consider the non-ideality of the electrolyte. Within this work, we elucidate a complete set of lithium-ion transport properties for mixtures of dimethyl carbonate terminated perfluorinated tetraethylene ether and lithium bis(fluorosulfonyl)imide (LiFSI). The steady-state current transference number is positive across all concentrations and decreases with salt concentration, while the NMR transference number is approximately 0.5 everywhere. In contrast, we find that the transference number using Newman’s concentrated solution theory is negative across all concentrations. We show that Newman’s concentrated solution theory allows for accurate potential and limiting current modeling of lithium half cells whereas the steady-state current transference number severely over-estimates the electrolyte’s limiting current. The disparity between the dilute solution theory measurements and that of Newman’s concentrated solution theory approach indicates the dominance of ion clustering. Figure 1

Autoignition behavior of a full boiling-range gasoline: Observations in RCM and GCI engine environments

The understanding of, and capability to modulate fuel autoignition behavior are important aspects towards the development of advanced, low temperature combustion (LTC) engine concepts, which have potential to significantly increase engine efficiency while at the same time addressing emissions concerns. Proper combustion phasing and control of heat release rates via, for instance, multiple injections and exhaust gas recirculation, are significant challenges that can vary with fuel composition. Overall reactivity, which is a strong function of the in-cylinder temperature and pressure, is a prime driver for regulating combustion timing, while preliminary exothermicity, in the form of low- and intermediate-temperature heat release (LTHR, ITHR) can inhibit, or facilitate operational success, e.g., control combustion phasing. There are still gaps in understanding these features and how they interact with needs of advanced combustion engines, and how practical fuels can be rated for the new challenges of LTC engines.This work utilizes a rapid compression machine (RCM) and gasoline compression ignition (GCI) engine to probe the autoignition behavior of a California Reformulated Gasoline Blendstock for Oxygenate Blending (CARBOB) (RON = 86, MON = 81.4) under quasi- homogeneous charge compression ignition (qHCCI) operation. A wide range of thermodynamic conditions is explored (Tc = 700–1000 K, Pc = 15–90 bar) where ignition delay times and LTHR/ITHR are quantified. Both stoichiometric, dilute (11% O2) and lean (equivalence ratio (ϕ) = 0.23) fuel loading conditions are considered. The GCI engine is operated under fuel-lean conditions (ϕ = 0.23) using no external exhaust gas recirculation over a range of intake temperature (Tin = 30–70 °C), with the intake pressure adjusted (Pin = 1.2–1.3 bar) to achieve constant combustion phasing (CA50 = −4 °aTDC). Preliminary exothermicity is also quantified under these conditions.The stoichiometric, dilute RCM measurements reveal negative temperature coefficient (NTC) behavior for this fuel and indicate that rates and extents of LTHR and ITHR are both affected by the compressed conditions, with temperature imposing an inverse dependence, while increased pressure causes LTHR to increases, but ITHR to decrease. These are the first experimental quantifications of ITHR trends for a practical fuel under well-controlled, static conditions. When the lean RCM measurements are mapped to the in-cylinder conditions of the engine, it is found that under a constant combustion phasing scenario (as used in the engine), the fuel has little overall temperature sensitivity, while the starts of high temperature heat release (soHTHR) and top dead center (TDC) points seen along the engine compression trajectories correspond to isopleths of ignition delay times τRCM = 6 and 3 ms, respectively. In addition, the points of peak LTHR rate in the engine correspond to an isopleth of first-stage ignition τ1,RCM = 0.50–0.75 ms. Correlating the magnitudes of LTHR and ITHR measured in the RCM to the engine requires quantification of the preliminary exothermicity at the thermodynamic conditions of peat LTHR rate and soHTHR, respectively. The current measurements demonstrate how fundamental data from an RCM can be used to project expected trends in overall fuel reactivity to a qHCCI engine environment, and thus provide a possible avenue for characterizing fuels for LTC engines.

Entrainment in pulsing plumes

Turbulent axisymmetric lazy plumes produced by discharging saline fluid downwards into a less dense uniform environment from a round pipe are examined experimentally. The plume development is controlled by the source flow rate $$Q_0$$ , momentum $$M_0$$ and buoyancy $$F_0$$ . This study investigated plumes where the source flow rate, momentum and buoyancy are sinusoidal functions of time. The pulsing flow is generated by a programmable ISMATEC gear pump. The maximum frequency f of this pulsing plume is of $$\mathcal {O}(U_0/D)$$ , where $$D/U_0$$ is the eddy turnover time scale at the source, D is the source diameter, and $$U_0$$ is the average velocity at the source. Experiments with pulsing plumes were carried out with a flow rate amplitude A of up to $$80\%$$ and with Strouhal number $$St=fD/U_0$$ ranging from 0.012 to 1.2. The bulk dilution and entrainment measurements were made using the experimental approach of Hunt and Kaye (J Fluid Mech 435:377–396, 2001). Average entrainment is obtained via the integral relationship for Q(z) and M(z) from the model established by Morton et al. (Proc R Soc Lond A 234(1196):1–23, 1956) for continuous sources. The influence of the amplitude and Strouhal number St on the entrainment coefficient $$\alpha$$ is examined, which was found to be very small over the entire range of source conditions considered.

A comparative assessment of dilution correction methods for spot urinary analyte concentrations in a UK population exposed to arsenic in drinking water

Spot urinary concentrations of environmental exposure biomarkers require correction for dilution. There is no consensus on the most appropriate method, with creatinine used by default despite lacking theoretical robustness. We comparatively assessed the efficacy of creatinine; specific gravity (SG); osmolality and modifications of all three for dilution correcting urinary arsenic. For 202 participants with urinary arsenic, creatinine, osmolality and SG measurements paired to drinking water As, we compared the performance corrections against two independent criteria: primarily, (A) correlations of corrected urinary As and the dilution measurements used to correct them - weak correlations indicating good performance and (B) correlations of corrected urinary As and drinking water As - strong correlations indicating good performance. More than a third of variation in spot urinary As concentrations was attributable to dilution. Conventional SG and osmolality correction removed significant dilution variation from As concentrations, whereas conventional creatinine over-corrected, and modifications of all three removed measurable dilution variation. Modified creatinine and both methods of SG and osmolality generated stronger correlations of urinary and drinking water As concentrations than conventional creatinine, which gave weaker correlations than uncorrected values. A disparity in optima between performance criteria was observed, with much smaller improvements possible for Criterion B relative to A. Conventional corrections – particularly creatinine - limit the utility spot urine samples, whereas a modified technique outlined here may allow substantial improvement and can be readily retrospectively applied to existing datasets. More studies are needed to optimize urinary dilution correction methods. Covariates of urinary dilution measurements still warrant consideration.

Viscosity of Semidilute and Concentrated Nonentangled Flexible Polyelectrolytes in Salt-Free Solution.

We report viscosity data of nonentangled sodium polystyrene sulfonate (NaPSS) in salt-free aqueous solution as a function of polymer concentration ( c) and degree of polymerization ( N). Different empirical equations are examined and found not to describe the semidilute solution viscosity over a wide concentration range and/or to yield values of [η] that do not match dilute solution measurements. Deviations from the scaling prediction of ηsp ∝ c1/2 (Fuoss' law) are observed at high concentrations. Specifically, we find ηsp ≈ N1.26 c1/2 e1.4 c in the semidilute regime, which agrees with the scaling prediction only for c ≲ 0.02 M. The viscosity data presented in this study and in earlier reports show a high degree of consistency. A comparison with diffusion measurements for NaPSS in salt-free solution by Oostwal and co-workers suggests that the disagreement between the scaling theory and experiments does not arise solely from the concentration dependence of the monomeric friction coefficient.

Self‐Assembly of Polyethylene Glycol Ether Surfactants in Aqueous Solutions: The Effect of Linker between Alkyl and Ethoxylate

AbstractThe aqueous self‐assembly behavior of two homologous series of poly(ethylene oxide) (PEO)‐containing nonionic surfactants based on a C10‐Guerbet hydrophobe is reported. The two families of surfactants, alkyl ethoxylates and alkyl alkoxylates, are commercially available from BASF under the trade name Lutensol® XP‐series and XL‐series, respectively. The latter incorporate propylene oxide (PO) units in the surfactant chain. Dye solubilization was used to determine the critical micellization concentration (CMC) of each surfactant at 22 and 50 °C. The PO‐containing alkyl alkoxylates displayed lower CMC values, which were also more sensitive to temperature. The Gibbs free energy, enthalpy, and entropy of micellization were computed from the CMC data and used to identify the contribution of each surfactant moiety (alkyl chain, PO unit, and PEO block) in controlling the CMC. The micellization properties are compared with compositionally similar surfactants with linear alkyl chains, yielding information about the effects of the Guerbet alkyl chain on micellization. Isothermal titration calorimetry was also used to characterize the CMC and enthalpy of micellization which generally compare well with the dye solubilization results. Cloud point data reveal nonmonotonic relationships for the Lutensol® surfactants with respect to composition, unlike linear alkyl chain surfactants. Finally, dilute solution viscosity measurements performed on some Lutensol® surfactants show a change in the slope, suggesting a structural change that tends to be more pronounced for surfactants with longer PEO blocks. The data presented herein enhance the understanding of surfactant structure–property relationships required for industrial formulation.

Application of trihexyltetradecylphosphonium dicyanamide ionic liquid for various types of separations problems: Activity coefficients at infinite dilution measurements utilizing GLC method

In this work, the ionic liquid trihexyltetradecylphosphonium dicyanamide [P 6 6 6 14] [DCA] was evaluated as a potential extraction solvent for organic compounds. The assessment was done based on the solute retention data obtained by gas liquid chromatography (GLC) for 33 solutes: (alkanes, alkenes, ketones, alcohols, alkynes, aromatic hydrocarbons, tetrahydrofuran, thiophene, acetonitrile and water). The experiment was conducted at a series of four temperatures (313.15–343.15) K at 10 K intervals. Experimental activity coefficients at infinite dilution data acquired over the investigated temperature range was then utilized to compute the thermodynamic functions at infinite dilution including partial molar excess enthalpy, ΔH1E,∞, Gibbs free energy, ΔG1E,∞ and entropy term, TrefΔS1E,∞. The selectivity and capacity values for some of the separation challenges (heptane/thiophene, water/butanol and heptane/benzene) were computed from the γ13∞ data and in contrast to the other phosphonium based ionic liquids in the literature. The selectivity and capacity data shows that the investigated ionic liquid can be utilized in the separation of heptane/thiophene or water/butan-1-ol mixtures.

3092 Measuring Fluid Compartments Before and After Rapid Saline Infusion

OBJECTIVES/SPECIFIC AIMS: To evaluate the ability of various techniques to track changes in body fluid volumes before and after a rapid infusion of saline. METHODS/STUDY POPULATION: Eight healthy participants (5M; 3F) completed baseline measurements of 1) total body water using ethanol dilution and bioelectrical impedance analysis (BIA) and 2) blood volume, plasma volume and red blood cell (RBC) volume using carbon monoxide rebreathe technique and I-131 albumin dilution. Subsequently, 30mL saline/kg body weight was administered intravenously over 20 minutes after which BIA and ethanol dilution were repeated. RESULTS/ANTICIPATED RESULTS: On average, 2.29±0.35 L saline was infused with an average increase in net fluid input-output (I/O) of 1.56±0.29 L. BIA underestimated measured I/O by −3.4±7.9%, while ethanol dilution did not demonstrate a measurable change in total body water. Carbon monoxide rebreathe differed from I-131 albumin dilution measurements of blood, plasma and RBC volumes by +0.6±2.8%, −5.4±3.6%, and +11.0±4.7%, respectively. DISCUSSION/SIGNIFICANCE OF IMPACT: BIA is capable of tracking modest changes in total body water. Carbon monoxide rebreathe appears to be a viable alternative for the I-131 albumin dilution technique to determine blood volume. Together, these two techniques may be useful in monitoring fluid status in patients with impaired fluid regulation.

Upscaling Mixing in Highly Heterogeneous Porous Media via a Spatial Markov Model

In this work, we develop a novel Lagrangian model able to predict solute mixing in heterogeneous porous media. The Spatial Markov model has previously been used to predict effective mean conservative transport in flows through heterogeneous porous media. In predicting effective measures of mixing on larger scales, knowledge of only the mean transport is insufficient. Mixing is a small scale process driven by diffusion and the deformation of a plume by a non-uniform flow. In order to capture these small scale processes that are associated with mixing, the upscaled Spatial Markov model must be extended in such a way that it can adequately represent fluctuations in concentration. To address this problem, we develop downscaling procedures within the upscaled model to predict measures of mixing and dilution of a solute moving through an idealized heterogeneous porous medium. The upscaled model results are compared to measurements from a fully resolved simulation and found to be in good agreement.

Imaging and quantification of magnetic nanoparticles: Comparison of magnetic resonance imaging and magnetic particle imaging

Abstract Quantification and imaging of magnetic nanoparticles is of vital importance for various novel biomedical applications, like cell tracking, drug targeting or hyperthermia treatments. In this work we studied the performance of magnetic resonance imaging (MRI) and magnetic particle imaging (MPI) for quantitative imaging of magnetic nanoparticles (MNP). This was done by measurements of serial dilutions of MNP (Ferucarbotran) in two different media (water and CuSO4 solution). The concentration range in which quantification was possible was determined for each technique, and the influence of the environment was analyzed and discussed. This revealed a significantly stronger influence of the surrounding medium on MRI performance as compared to MPI. All results were validated by measurements using their respective zero-dimensional (spectroscopic) techniques nuclear magnetic resonance and magnetic particle spectroscopy, showing similar behavior compared to the imaging modalities. Physical explanations of all observed effects are given, and a concentration range is determined in which the advantages of both imaging techniques can be utilized.

Equilibrating stable Cd isotopes with acidic soils

ABSTRACT Cadmium (Cd) in the soil solution is in dynamic equilibrium with the reservoir of bioavailable Cd attached to the solid phase, i.e. the labile pool (CdE). Traditionally, CdE is estimated using the radioisotope 109Cd, which has severely restricted access to estimates of CdE. Using stable isotope dilution and isotope ratio measurement by inductive coupled plasma-quadrupole mass spectroscopy (ICP-QMS) would increase access to estimates of CdE; however, detail remains scant about the optimal conditions for equilibration and measurement. We report optimal conditions for spiking with 110Cd, batch equilibration and ICP-QMS measurement of the ratio of 110Cd to 111Cd using results for six acidic soils with total Cd concentrations of 0.19–6.4 mg Cd kg−1, suspended in three background electrolytes (10 mM CaCl2, 1 M NH4NO3, and 1 M NH4Cl). Our optimised procedure produces robust estimates of CdE. Application of this approach will greatly increase access to estimates of CdE and to the investigation of its role in Cd uptake by plants.

Well flow and dilution measurements for characterization of vertical hydraulic conductivity structure of a carbonate aquifer

The paper aims to characterize vertical variations in horizontal hydraulic properties in a fractured carbonate aquifer, the Cretaceous Chalk in East Yorkshire, UK. Two approaches are used: an inverse model of well flow applied to flow logs of pumped open wells, and open well dilution testing. In this case study, transmissivity in the unconfined part of the aquifer is dominated by the highly permeable zone of water table fluctuation, where carbonate dissolution has occurred enhancing fracture aperture; a similar enhanced permeability zone is present at the top of the aquifer where it is confined beneath glacial deposits, although periglacial physical weathering during Quaternary cold periods, rather than carbonate dissolution, is responsible. The aquifer is also shown to contain deeper permeable horizons of stratigraphic origin, which are better developed in the unconfined section.