Absorption Fraction Research Articles

Derivation of whole blood biomonitoring equivalents for lithium for the interpretation of biomonitoring data

IntroductionLithium salts have numerous industrial uses and are also used in the treatment of bipolar disorders. The main source of lithium exposure to the general population is drinking water and foods. Lithium is nephrotoxic at higher doses. Thus, oral exposure guidelines for lithium have been derived, including ICH's permitted daily exposure (PDE = 0.008 mg lithium/kg-bw/day) adopted by Health Canada and the United States Environmental Protection Agency's (U.S. EPA) provisional peer reviewed toxicity value (PPRTV = 0.002 mg lithium/kg-bw/day), both based on human data. ObjectiveTo derive whole blood biomonitoring equivalents (BEs) associated with PDE and PPRTV to interpret population-level biomonitoring data in health risk context. MethodA simple kinetic relationship based on plasma clearance value (0.5 L/kg-bw/day) and the oral absorption fraction (100%) was used to derive blood BEs for PDE and PPRTV. ResultsThis analysis resulted in BE values in plasma and whole blood of 16 and 10 μg/L, respectively, based on the PDE values developed by the Health Canada and of 4.2 and 2.7 μg/L, respectively, based on the PPRTV developed by U.S. EPA. ConclusionThe derived BE values can be used to interpret population-level biomonitoring data.

An elliptic numerical analysis of water vapour absorption into a falling film in vertical parallel plate channels

An implicitly coupled elliptic numerical model is applied to study the two-phase falling film absorption inside a parallel plate vertical channel. A complete set of two-phase two-dimensional governing equations are solved for co-current laminar flows of LiBr solution and water vapour. A precise liquid-gas interface is determined dynamically during solution over a non-orthogonal structured moving mesh. Fundamental interface boundary conditions are implemented to model the heat and mass interchange between the two phases. The capability of this new model is demonstrated through detailed comparisons with two previous parabolic and elliptic models. The impacts of the interface heat of absorption and mass fraction condition and the liquid film diffusion coefficient are investigated. New results are presented to examine the channel inlet pressure effect on the liquid film thickness development over the cold wall and the heat and mass transfer at the interface.

Development of a Two-Compartment System In vitro Dissolution Test and Correlation with In vivo Pharmacokinetic Studies for Celecoxib

The objective of this study was to develop a novel open-mode two-compartment system dissolution apparatus to simulate the dissolution and absorption of poorly soluble drugs and to establish an in vitro-in vivo correlation (IVIVC). Celecoxib (CEB) was selected as a model drug, and in vitro dissolution was performed using the novel dissolution apparatus with acetate buffers at pH 4.5 containing Tween 80 (0.15%, w/v), at a flow rate of 30mL/min and an agitation rate of 50rpm. Cumulative release of all formulations was incomplete at approximately 70-80%, which likely reflected in vivo dissolution. Corresponding pharmacokinetic studies were performed in which twelve healthy male subjects from two bioequivalence studies received either one immediate release (IR) dose of the test (test 1 or test 2) or the reference formulation (Celebrex®, 200mg). Individual plasma profiles of the formulations were deconvoluted via the Wanger-Nelson method to obtain the mean absorption fractions. A level A correlation was successfully developed with a good R2. The Weibull equation was used to describe the in vitro dissolution and in vivo absorption kinetics. In vitro dissolution correlated with in vivo absorption was applied successfully to predict the in vivo plasma concentrations-time profiles of the CEB formulations. Compared with conventional methods, the novel dissolution device showed great potential for discriminating the dissolution between formulations and generic drugs, which may provide a tool for making in vivo predictions for next bioequivalence trials.

Polarization and matching modulation of peapod-like Cu/C nanowires to improve microwave absorption

Unique peapod-like Cu/C core-shell nanowires (CSNWs) were specifically designed and synthesized to overcome the disadvantages of Cu NWs (i.e., low microwave absorption capability, poor chemical stability, and high density) for applications in microwave devices. Herein, Cu/C CSNWs were synthesized via a hydrothermal-sintering approach, in which the structural evolution from solid NWs to peapod-like NWs and even to hollow nanotube can expediently be achieved by changing the aging time. Such changes can effectively modulate impedance matching, dielectric loss, and conductivity. Compared with other Cu-based absorbers, the present peapod-like Cu/C CSNWs exhibited broader effective bandwidth of (6.96 GHz; RL ≤ −10 dB), strong absorption (- 39.43 dB) and lower filling mass fraction (15 wt%). The superior performance with broad band, light weight, and strong absorption of the CSNWs can be attributed to the enhanced impedance matching and permittivity, low filling mass fraction, high attenuation, multiple scattering, and plasmon resonance absorption. Moreover, the carbon shell significantly improved chemical stability. This work presents a new strategy to design advanced peapod-like microwave absorbers for various microwave absorption applications.

Effects of Tillage Systems on Labile Fractions of Soil Organic Nitrogen of a Freeze-Thaw Agricultural Area in Northeast China

The impact of tillage systems is obvious in the nitrogen mineralization. Few studies have focused on the relationship between labile fraction of soil organic nitrogen (SON) and crop nitrogen absorption under different tillage systems in freeze-thaw agricultural area. In this study, the effects of conventional tillage (CT) and no-tillage (NT) on the labile fractions of soil organic nitrogen and the relationships with the potentially mineralizable nitrogen (N0) at different soil depths in seeding, jointing, filling and maturity seasons over four years (2010, 2011, 2015 and 2016) were explored. It has been demonstrated that the labile fractions of SON and N0 in NT were higher than in CT at 0-5, 0-10 and 0-20cm. N0 was positively and highly related to the medium particulate organic carbon (mPOM-C) (P<0.01) under CT and NT, whereas highly significant and negative correlations (P<0.01) between N0 and medium particulate organic nitrogen (mPOM-N) were detected under both tillage systems at 0-5 and 0-10cm. The difference in these correlations between tillage systems had been found to be the most notable at the 0-5cm depth. The higher SON fractions content would contribute to the nitrogen mineralization potential because of freeze-thaw conditions during the crop growing season.

Изучение воздействия УФ излучения на смолы и асфальтеновые фракции сырой нефти методом ИК спектроскопии

In this work, the dependences of the intensity of the IR spectra of resins and asphaltenes on the time of irradiation during their photolysis under the action of radiation from a mercury lamp are studied. It was found that an increase in the irradiation time leads to a decrease in the intensity of absorption bands corresponding to normal paraffin. The observed pattern is explained on the basis of the transfer of excitation energy from PAH molecules to alkane molecules. Based on the values ​​of the extinction coefficient and the relative concentration of PAHs in crude oil, the fractions of absorption of UV light energy by molecules of individual PAH components were calculated.

Development of a low cost nanofluid based direct absorption solar collector

Abstract In this work experimental investigation on a parabolic trough direct absorption solar collector (PTDASC) working with a cost effective carbon soot based nanofluid is performed. DASC employs absorption of solar radiation directly by the fluid instead of the solid surface. The main components of the PTDASC are the glass-glass receiver tube and nanofluid. Carbon soot synthesized cheaply by incomplete combustion of inorganic materials like candle, paraffin and oxygen-acetylene was dispersed in DI water to form carbon soot nanofluid. The mass fraction of carbon soot/water nanofluid selected for testing in PTDASC was 0.2 %. Solar weighted absorption fraction measured by UV-Vis spectrophotometer indicated that 70% of the incident energy can be absorbed by carbon soot nanofluid. The maximum thermal efficiency of the collector was found to be 50 % for nanofluid and 12.4 % for base fluid. The carbon soot nanofluid based on candle soot exhibited excellent volumetric absorption property.

Emission characteristics of size distribution, chemical composition and light absorption of particles from field-scale crop residue burning in Northeast China

Crop residue burning in China increased significantly in the last decade, especially it took up a majority in Northeast China, which plays an important role of severe haze pollution. Hence, two main types of crop residues (corn and rice straw) were chosen to characterize the particle number concentration, chemical components of fine particulate matter and optical properties of carbonaceous aerosols by a suite of fast-response online portable instruments, together with offline sampling and analysis, during the field-based combustion experiments in Northeast China. For the range of 250 and 2500 nm, more particles were emitted from rice straw burning than those from corn straw burning, and the time-averaged number concentration of particles during the flaming process was approximately 2 times higher than that during the smoldering process for these two straws. Organic carbon (OC), elemental carbon (EC) and water-soluble ions were the most abundant components and accounted for 42.5 ± 7.5%, 7.7 ± 1.7% and 18.0 ± 3.4% of the PM2.5, respectively. Furthermore, rice straw burning emitted higher OC and lower Cl− and K+ than those from corn straw burning. The average absorption Ångström exponent (AAE) of carbonaceous aerosols was 2.1 ± 0.3, while the AAE of brown carbon (BrC) was 4.7 ± 0.4 during the whole burning process. On average, BrC contributed to 63% and 20% of the total light absorption at 375 nm and 625 nm, respectively. Parameterization of BrC absorption revealed that the fraction of absorption from BrC has a reasonably good correlation with EC/OC (−0.84) and AAE (0.94) at 375 nm. Generally, combustion conditions can affect the optical properties of carbonaceous aerosols, and a negative correlation (−0.77) was observed between the AAE and modified combustion efficiency; in addition, the percentage of absorption due to BrC were lower at the flaming phase.

The Amorphization of Monolayer MoS2 Induced by Strong Oxygen Plasma Treatment

By strong oxygen plasma treatment on monolayer MoS2, we observe the disappearance of the Raman modes of MoS2. We propose the hypothesis that the state of MoS2 translates from crystal to amorphous after strong oxygen plasma treatment. The evidences of no MoO3 formation shown by Raman spectra and the appearance of the Mo6+ peak and decreased O concentration shown by X-ray photoelectron spectroscopy support our hypothesis. The amorphization of monolayer MoS2 is further confirmed by the quenching of photoluminescence (PL) and the disappearance of two absorption peaks related to A, B exciton which demonstrates the disordered bandgap. Finally, we found that the amorphous MoS2 can improve the absorption fraction at the visible light (500~ 750 nm) which is potential for future visible light photocatalysis.

Investigation on influence of antimony tin oxide/silver nanofluid on direct absorption parabolic solar collector

This paper discusses the synthesis and characterization of a novel hybrid nanofluid and its performance analysis on a parabolic trough direct absorption solar collector. Broadening the absorption spectra of working fluid using nanoparticles is the new research revolution for increasing the volumetric solar absorption efficiency. It is reported that plasmonic silver nanoparticles have higher absorption in visible spectra while antimony doped tin oxide has an absorption peak in the near-infrared region. Hence, antimony tin oxide/silver hybrid nanoparticle with broad spectral absorptivity was synthesized. Optimization of the nanofluid composition performed using response surface methodology yielded an optimized mass fraction of antimony tin oxide and surfactant, sodium dodecyl sulfate, as 0.1% each. The solar weighted absorption fraction of optimized nanofluid was obtained as 90.12%. Performance evaluation of the solar collector was based on ASHRAE standards 93–2010. The optical efficiency of the parabolic collector was calculated to be 75%. The maximum thermal efficiency obtained by the optimized nanofluid applied parabolic trough direct absorption solar collector was 63.5% at a flow rate of 0.022 kgs−1 and the highest exergy efficiency obtained was 5.6%. Thermal and exergy efficiency was observed to increase with increase in flow rate.

A first quantification of the effects of absorption for H I intensity mapping experiments

Context. HI intensity mapping (IM) will be used to do precision cosmology, using many existing and upcoming radio observatories. It will measure the integrated HI 21 cm emission signal from “voxels” of the sky at different redshifts. The signal will be contaminated due to absorption, the largest component of which will be the flux absorbed by the HI emitting sources themselves from the potentially bright flux incident on them from background radio continuum sources. Aims. We, for the first time, provide a quantitative estimate of the magnitude of the absorbed flux compared to the emitted HI flux. The ratio of the two fluxes was calculated for various voxels placed at redshifts between 0.1 and 2.5. Methods. We used a cosmological sky simulation of the atomic HI emission line, and summed over the emitted and absorbed fluxes for all sources within voxels at different redshifts. In order to determine the absorbed flux, for each HI source the flux incident from background radio continuum sources was estimated by determining the numbers, sizes, and redshift distribution of radio continuum sources that lie behind it, based on existing observations and simulations. The amount of this incident flux that is absorbed by each HI source was calculated using a relation between integrated optical depth with HI column density determined using observations of damped Lyman-α systems (DLAs) and sub-DLAs. Results. We find that for the same co-moving volume of sky, the HI emission decreases quickly with increasing redshift, while the absorption varies much less with redshift and follows the redshift distribution of faint sources that dominate the number counts of radio continuum sources. This results in the fraction of absorption compared to emission to be negligible in the nearby Universe (up to a redshift of ∼0.5), increases to about 10% at a redshift of one, and continues to increase to about 30% up to a redshift of 2.5. These numbers can vary significantly due to the uncertainty on the exact form of the following relations: firstly, the number counts of radio continuum sources at sub-mJy flux densities; secondly, the relation between integrated optical depth and HI column density of HI sources; and thirdly, the redshift distribution of radio continuum sources up to the highest redshifts. Conclusions. Absorption of the flux incident from background radio continuum sources might become an important contaminant to HI IM signals beyond redshifts of 0.5. The impact of absorption needs to be quantified more accurately using inputs from upcoming deep surveys of radio continuum sources, H I absorption, and HI emission with the Square Kilometre Array and its precursors.

A Search for Intrinsic H i 21 cm and OH 18 cm Absorption toward Compact Radio Sources

Abstract We present the results of a large search for intrinsic H i 21 cm and OH 18 cm absorption in 145 compact radio sources in the redshift range 0.02 &lt; z &lt; 3.8 with the Green Bank Telescope. We redetect H i 21 cm absorption toward six known absorption systems, but detect no new H i or OH absorption in 102 interference-free sources. Seventy-nine sources have not previously been observed for H i 21 cm absorption. We recover a mean optical depth limit of τ 3σ &lt; 0.023 for all the nondetections in the survey. Our results do not support the high intrinsic absorption rates found by previous studies in compact radio sources at low redshift. Our results do, however, support the hypothesis proposed by Curran et al. that high ultraviolet (UV) luminosity active galactic nuclei do not show intrinsic H i 21 cm absorption, confirming a threshold of L UV = 1023 W Hz−1, above which our intrinsic absorption fraction is zero (54 sources). The exact nature of the UV luminosity effect on H i absorption systems remains ambiguous. We additionally find no statistical correlation between the 1.4 GHz radio luminosity or the source size and the 21 cm absorption detection rate. We attribute the lack of intrinsic absorption in our survey to the UV luminosity effect caused by an optical selection bias and a decreased column density sensitivity with increasing redshift due to lower radio continuum flux densities, high radio frequency interference, and higher telescope system temperatures at low frequencies.

Optimisation of thermo-optical properties of SiO2/Ag–CuO nanofluid for direct absorption solar collectors

Augmenting thermal and optical properties of working fluids used in solar thermal conversion systems using hybrid nanomaterials is gaining prominence. In the present study photo-thermal analysis and thermal conductivity investigations were performed on SiO2/Ag–CuO binary water based nanofluid. The influence of particle concentration and surfactant concentration on thermo-optical properties were investigated using the design of experiment concept. Analysis of variance (ANOVA) was employed to study the significance of the process parameters on thermal conductivity and solar weighted absorption fraction of nanofluid. The statistical optimisation of the process parameters was done using the desirability function. The optimum combination of nanoparticles and surfactant that yield good thermal conductivity and solar absorption was found to be SiO2/Ag: 206.3 mg/L, CuO: 864.7 mg/L, and SDS (surfactant): 1996.2 mg/L. The optimum mass fraction of constituents yielded a relative thermal conductivity of 1.234 and solar weighted absorption fraction of 82.82%.

Simultaneous Evaluation of Dissolution and Permeation of Oral Drug Solid Formulations for Predicting Absorption Rate-Limiting Factors and In Vitro-In Vivo Correlations: Case Study Using a Poorly Soluble Weakly Basic Drug.

Combined dissolution and permeation systems are designed to simultaneously assess the dissolution of a pharmaceutical dosage form and the permeation of dissolved drugs therefrom. However, there were still some limitations on predicting the possible absorption rate-limiting steps and improving the in vitro-in vivo correlation (IVIVC) of a complete dosage form. In this study, the modified biorelevant media with some solubilizers and pH modifiers were integrated into the drug dissolution/absorption simulating system (DDASS). Indapamide, a poorly soluble compound (pKa = 8.8), was selected to validate the applicability of the modified biorelevant media. The elution and permeation dynamics of indapamide were investigated by using appropriate solubilizing agents in the DDASS. The absorption behaviors were analyzed after oral administration of indapamide in beagle dogs. The absorption rate-limiting steps and IVIVCs were predicted from the dissolution-permeation-absorption dynamic parameters. As a result, the absorption fraction of indapamide in the FaSSIFmod of DDASS was estimated to be approximately 100%, in accordance with its high permeability. The ratios of permeation rate to elution rate were 2.55 and 3.34 for the immediate- and sustained-release tablets of indapamide, respectively, suggesting a dissolution rate-limiting absorption for indapamine. In addition, point-to-point correlations were established between in vitro elution and in vivo absorption by the nonlinear and linear regression analysis ways (r > 0.85). The findings indicate that DDASS is a promising technique to develop improved IVIVCs of a complete dosage form, and the FaSSIFmod is suitable to predict the possible absorption rate-limiting steps of poorly soluble drugs in DDASS.

On the importance of field driven single particle processes in short pulse absorption of clusters

Nano-clusters are acclaimed to be very efficient absorbers of intense femto second light due to dominant collective mechanisms. Enhanced near 100% absorption due to collective linear plasma resonance compared to a small fraction of absorption by unclustered gas was an important drive in nano-plasma studies. Contrary to such perception, we show that if the pulse duration is (<100 fs), absorption is same irrespective of whether the systems are condensed to large clusters or not. So long as there are same number of similar ionizable systems in the focal volume, absorption is the same and such absorption can be accounted for by single particle response to the field and collisional ionization of atoms. Short pulse absorption by the single particle response can be comparable to the linear plasma resonance absorption for smaller clusters.

Chelation Treatment by Early Inhalation of Liquid Aerosol DTPA for Removing Plutonium after Rat Lung Contamination.

Occupational contamination is a potential health risk associated with plutonium inhalation. DTPA remains the chelating drug of choice to decorporate plutonium. In this study, plutonium was found to be more effectively removed from lungs by a single inhalation of nebulized DTPA solution at only 1.1 µmol.kg-1 than by a single intravenous (i.v.) dose of DTPA at 15 µmol.kg-1. When DTPA was inhaled promptly after contamination, it removed the transportable fraction of plutonium prior blood absorption, thereby preventing both liver and bone depositions. Conversely, DTPA injection was better than inhalation at reducing the extrapulmonary burden, probably due to the much greater circulating dose, favoring the mobilization of plutonium already translocated. Thus, prompt inhalation, concomitantly supplemented with i.v. injection, of DTPA induced an important decrease in extrapulmonary deposits. Repeated DTPA inhalations over several weeks were more efficient than a single inhalation in limiting both pulmonary and extrapulmonary plutonium retention, due at least in part to the chelation of the transportable fraction of lung plutonium. Furthermore, repeated DTPA injections remained better at reducing liver and bone plutonium retentions. Taken together, our results suggest that multiple DTPA inhalations may be considered an effective treatment after inhalation of plutonium, particularly given the ease of this needle-free delivery, for the two following conditions: 1. A treatment combining i.v. injection and inhalation should be given in an emergency scenario to efficiently chelate the activity already absorbed; 2. Inhalations should be administered daily to effectively trap the early transferable fraction.

Applicability analysis and evaluation of aglycones in single-pass intestinal perfusion technique based on PBPK model

Single-pass intestinal perfusion( SPIP) is the common carrier of biopharmaceutics classification system( BCS) to study compound permeability. With the application and deepening study of BCS in the field of traditional Chinese medicine( TCM),SPIP model is becoming more and more common to study the intestinal absorption of TCM ingredients. Based on the limitations of the SPIP model in some researches on TCM permeability,it was speculated in this study that aglycone may be more suitable than the glycoside to study the intestinal absorption problem by using SPIP model. Furthermore,applicability of aglycone components was analyzed and evaluated. In this study,with quercetin,daidzein,formononetin,genistein and glycyrrhetinic acid used as research objects,the quantitative study of SPIP was used to evaluate the intestinal permeability of these aglycones and to predict the effective permeability coefficient( Peff) and absorption fraction( Fa) in human body. By combining studies comparison and analysis on multiple permeability research methods and prediction of human body absorption of aglycones in physiological-based pharmacokinetic models,this paper can further illustrate that the SPIP model is a good tool for studying the permeability of aglycones and predicting human absorption,which can provide data foundation and theoretical reference for researches on SPIP technique and BCS in intestinal absorption of TCM ingredients.

Effect of Volume Fraction and Solutions Absorption on The Properties of Epoxy/Carbon Fiber Composites

Effect of Volume Fraction and Solutions Absorption on The Properties of Epoxy/Carbon Fiber Composites

Synergistic effect of hybrid Himalayan Nettle/Bauhinia-vahlii fibers on physico-mechanical and sliding wear properties of epoxy composites

The cellulosic bast fibers are recognized as a justifiable and biodegradable substitute for producing moderate strength polymer composite materials because of their characteristics of renewability, eco-friendliness, and higher specific strength. Hence the aim of this research work is to fabricate Himalayan bast fibers (Nettle fiber (NF)/bauhinia vahlii fiber (BF)) based mono/hybrid epoxy composites at varying weight percentage of 2–6 wt% and evaluate the physical (void fraction and water absorption), mechanical (tensile strength, flexural strength, hardness) and sliding wear properties of as-fabricated composites. The 6 wt% NBF reinforced composites exhibited higher mechanical properties as compared to NF and BF composites with tensile strength of 34.04 MPa, flexural strength of 42.45 MPa, and hardness of 37.01 Hv respectively. The influence of various control factors (sliding velocity, NF/BF/NBF contents, normal load and sliding distance) on specific sliding wear rate of composites was evaluated by Taguchi (three factors at three levels) experimental design and the percentage contribution of these selected parameters on sliding wear performance was examined by Analysis of variance (ANOVA). The sliding wear property of as-developed composites was found to be greatly influenced by sliding velocity and the wear resistance was observed to be improved with the NF/BF/NBF contents. The wear mechanism of the as-fabricated composites has been elucidated by scanning electron microscopy analysis. The research outcomes demonstrated that the hybridization of Bauhinia vahlii fiber with Nettle fiber led to improve the mechanical and wear properties of epoxy composites.

Anharmonicity in the mid-infrared spectra of polycyclic aromatic hydrocarbons: molecular beam spectroscopy and calculations

Aims. In this work we determine the effects of anharmonicity on the mid-infrared spectra of the linear polycyclic aromatic hydrocarbons (PAHs) naphthalene, anthracene, tetracene and pentacene recorded using the free electron laser FELIX. Methods. Comparison of experimental spectra obtained under supersonic jet conditions with theoretically predicted spectra was used to show if anharmonicity explicitly needs to be taken into account. Results. Anharmonic spectra obtained using second-order vibrational perturbation theory agree on average within 0.5% of the experimental frequencies. Importantly, they confirm the presence of combination bands with appreciable intensity in the 5–6 μm region. These combination bands contain a significant fraction of the IR absorption, which scales linearly with the size of the PAH. Detection and assignment of the combination bands are a preliminary indication of the accuracy of far-IR modes in our anharmonic theoretical spectra. Detailed analysis of the periphery-sensitive CH out-of-plane band of naphthalene reveals that there is still room for improvement of the VPT2 approach. In addition, the implications of our findings for the analysis of the aromatic infrared bands are discussed.