Penetration Volume Research Articles

Effective medium approximations for penetrant sorption in glassy polymers accounting for excess free volume

An accurate determination of a penetrant volume fraction in a swollen polymer is of crucial importance in a range of different technologies. Using optical methods, such as in-situ spectroscopic ellipsometry, it is possible to extract the thickness and refractive index of dry and swollen polymer films. The volume fraction of the penetrant can then be calculated from the change in thickness, or from the refractive index using effective medium approximations. For thermodynamically equilibrated and ideal swollen rubbery polymers, these calculations yield accurate results. However, for glassy polymers the influence of the excess free volume trapped within the polymer network during vitrification is rarely taken into account. In this work we investigate the effect of excess free volume in the calculations of penetrant volume fraction in a model glassy polymer – penetrant system. The influence of the excess free volume is included by extrapolating the properties of an equilibrium polymer matrix from above its glass transition temperature. The error between the approaches that do, and do not, take account for the non-equilibrium of the glassy polymer is quantified and the implications for other systems are discussed. The errors are shown to be very significant, especially when the dry polymer has a large excess free volume. Such materials are particularly relevant in membrane applications.

Heat transfer and fluid flow in additive manufacturing

In laser-based direct energy deposition additive manufacturing, process control can be achieved through a closed loop control system in which thermal sensing of the melt pool surface is used to adjust laser processing parameters to maintain a constant surface geometry. Although this process control technique takes advantage of important in-process information, the conclusions drawn about the final solidification structure and mechanical properties of the deposited material are limited. In this study, a validated heat transfer and fluid flow laser welding model are used to examine how changes in processing parameters similar to those used in direct energy deposition processes affect the relationships between top surface and subsurface temperatures and solidification parameters in Ti-6Al-4V. The similarities between the physical processes governing laser welding and laser-based additive manufacturing make the use of a laser welding model appropriate. Numerical simulations show that liquid pools with similar top surface geometries can have substantially different penetration depths and volumes. Furthermore, molten pool surface area is found to be a poor indicator of the cooling rate at different locations in the melt pool and, therefore, cannot be relied upon to achieve targeted microstructures and mechanical properties. It is also demonstrated that as the build temperature increases and the power level is changed to maintain a constant surface geometry, variations in important solidification parameters are observed, which are expected to significantly impact the final microstructure. Based on the results, it is suggested that the conclusions drawn from current experimental thermography control systems can be strengthened by incorporating analysis through mathematical modeling.

Comparative Study of Biodiesel and Diesel Jets in Gaseous Crossflow

This study compares the fundamental spray characteristics, such as penetration depth, droplet diameter, velocity, and volume flux of, biodiesel and diesel as well as their blends. Liquid jet is injected into an air crossflow with a speed of . A series of experimental tests covering Weber numbers from 29–82, and momentum flux ratios from 10–133, are conducted using the shadowgraph method and phase Doppler particle analyzer. The shadowgraph images are processed to find the penetration depth and to investigate different regimes of breakup. The phase Doppler particle analyzer is used to capture droplet size distribution, velocity, and volume flux. The results differ remarkably in terms of breakup regimes and trajectory for biodiesel blends, which may be due to the high viscosity of biodiesel in comparison to diesel. For example, at a Weber number of 80, some bag breakups are observed on the biodiesel jet against the expectation that, at this Weber number, most of the liquids experience atomization mode.

Metakaolin concrete: Carbonation and chloride behavior

The purpose of this paper is to present the results obtained in an experimental study that analyzed the performance of different concrete mixes. These mixes were produced with 90% of ordinary Portland cement (OPC) and the other 10% with the additions of metakaolin (MK) and silica fume (SF). Four types of MK were tested; two of these were produced by a thermal treatment on Colombian kaolin. The others two were imported from the international commercial market. The factors evaluated in all the concrete mixes were the following: compressive strength, water absorption and total volume of permeable porosity, capillary absorption, carbonation depth and chloride penetration. The concrete samples were submitted into an accelerated carbonation process inside a climatic chamber (30º C, 70% H.R. and 2.25% CO2 ). At 28 days of curing the carbonation depths for the blended concrete mixtures were greater than the one obtained in the OPC concrete without addition. With a prolonged curing age in all samples, with or without mineral additions, tend to slow the carbonation rate in the concrete. The resistance of the concrete to the chloride penetration was evaluated according to ASTM standard C1202. This study proved that blended concrete specimens have a lower capillary absorption and a higher chloride penetration resistance once these were compared with OPC concrete specimens without addition.

Tibial Cementing in UKA: A Three-Dimensional Analysis of the Bone Cement Implant Interface and the Effect of Bone Lavage

Loosening is a common cause for revision in cemented UKA. In a cadaver study, we analyzed the three-dimensional cement distribution under the tibial implant and the effect of bone lavage (pulsed lavage, syringe lavage) on maximum cement penetration and penetration volume. Analyses were determined by performing bone cuts in medio-lateral direction and converting this data into a 3D model. Pulsed lavage led to an increased mean maximum cement penetration 5.79 ± 2.63 mm and penetration volume 6471.34 ± 1156.43 mm(3) compared to syringe lavage 4.62 ± 2.61 mm, 5069.81 ± 1177.09 mm(3) (P<0.001; P<0.001). Our results show a complete cement mantle for both investigated lavage techniques. Cleansing the cancellous tibial bone bed using pulsed lavage is more effective than conventional syringe lavage and leads to a deeper cement penetration and lager cement penetration volume under the tibial component.

Equilibrium and transient sorption of vapours and gases in the polymer of intrinsic microporosity PIM-1

The gravimetric sorption technique was used for the study of equilibrium and transient sorption of various groups of vapours (alcohols, hydrocarbons, water) and gases (methane, nitrogen, oxygen, carbon dioxide) in the polymer of intrinsic microporosity PIM-1 at 25°C. Sorption isotherms of all compounds, except gases and water, exhibited S-shaped character, while the isotherms of gases are linear or concave over the inspected pressure region. Sorption isotherms of vapours were quantitatively parameterized with the Guggenheim, Anderson and de Boer (GAB) layered-adsorption model, which provided a comparable approximation of the data on carbon dioxide as the dual mode sorption model. Abnormally fast kinetics of transient sorption (superdiffusion) was observed in the region of diluted and saturated vapours of all measured compounds, except water, n-butane and carbon dioxide. The anomalous sorption kinetics was well parameterized with the convective–diffusion model. The anomalous nature of the mass transport in PIM-1 is also demonstrated by distinct trends for gases, alkanes and alcohol vapours in the correlations of diffusion coefficients with penetrant molecular volume and solubility coefficients with the square of critical temperature. The results obtained in this work indicate the occurrence of a transport mode that has a different nature than the classically employed solution-diffusion model.

Study on Treatment of Swine Wastewater by Sodium Type Mercerizing Zeolite

The efficiency of swine wastewater treatment was studied by static experiment and dynamic experiment, using sodium type mercerizing as adsorbent. The optimum parameter condition for swine wastewater treatment summarized. The experimental results showed that the optimum parameters were pH=8.0, t=24h, T=25, 300 g/L zeolite in the static experiment. In dynamic experiment when the velocity was 6 BV/h, 12 BV/h and 24 BV/h, the penetrating capacity and volume of ammonia-nitrogen, phosphorus and CODCr were calculated. The removal efficiency of ammonia-nitrogen, phosphorus and CODCr was highest under the velocity of 12 BV/h. Penetrates capacity of ammonia nitrogen and phosphorus were 4.04 mg/g and 0.14 mg/g, penetrates volume were 29 BV and 58 BV, respectively.

Cardiogenic mixing increases aerosol deposition in the human lung in the absence of gravity

RationaleExposure to extraterrestrial dusts is an almost inevitable consequence of any proposed planetary exploration. Previous studies in humans showed reduced deposition in low-gravity compared with normal gravity (1G). However, the reduced sedimentation means that fewer particles deposit in the airways, increasing the number of particles transported to the lung periphery where they eventually deposit albeit at a smaller rate than in 1G. In this study, we determined the role that gravity and other mechanisms such as cardiogenic mixing play in peripheral lung deposition during breath holds. MethodsEight healthy subjects inhaled boluses of 0.5μm-diameter particles to penetration volumes (Vp) of 300 and 1200ml that were followed by breath holds of up to 10s. Tests were performed in 1G and during short periods of microgravity (μG) aboard the NASA Microgravity Research Aircraft. Aerosol deposition and dispersion were calculated from these data. ResultsResults show that, for both Vp, deposition in 1G was significantly higher than in μG. In contrast, while dispersion was significantly higher in 1G compared to μG at Vp=1200ml, there was no significant gravitational effect on dispersion at Vp=300ml. Finally, for each G level and Vp, deposition and dispersion significantly increased with increasing breath-hold time. ConclusionThe most important finding of this study is that, even in the absence of gravity, aerosol deposition in the lung periphery increased with increasing residence time. Because the particles used in this study were too large to be significantly affected by Brownian diffusion, the increase in deposition is likely due to cardiogenic motion effects.

A comparative evaluation of ablations produced by high-frequency coagulation-, argon plasma coagulation-, and cryotherapy devices in porcine liver

Hepatic resection is the only curative treatment option for primary or metastatic malignancies of the liver. Although R1 resections can also lead to prolonged survival, the main surgical goal is complete tumor resection (R0). To achieve this, additional treatment of the resection margin with ablation devices is discussed. Using a porcine in vivo model, we therefore analyzed the effect of different ablation devices on depth and completeness of hepatic parenchymal cell destruction. Swabian-Hall strain pigs underwent ablation on the surface of the right, middle, or left liver lobe using seven different types of high-frequency (HF)-, cryotherapy (Cryo)-, or argon plasma coagulation (APC) devices. Penetration depth and volume were analyzed from histological sections. Severity of parenchymal cell destruction was assessed by a histomorphological score. The greatest penetration depth was achieved with Cryo (10.4 ± 1.7 mm), whereas HF and APC exhibited a smaller penetration depth. However, HF and APC compared to Cryo achieved complete destruction of the intralobular architecture and hepatocellular morphology depending on the application time and the adjusted power. HF, APC, and Cryo applied to the liver surface induce different parenchymal penetration depth and cell destruction. HF and APC are considered to be standard surgical instruments and therefore recommended as standard treatment, whereas Cryo may be used only if particularly deep penetration is required.

Intraperitoneal clearance as a potential biomarker of cisplatin after intraperitoneal perioperative chemotherapy: a population pharmacokinetic study

Background:Intraperitoneal (IP) perioperative chemotherapy with cisplatin is an interesting option in ovarian cancer treatment. A combination of cisplatin with IP epinephrine (already shown to improve IP and decrease systemic platinum (Pt) exposure) was evaluated using a population pharmacokinetic analysis.Methods:Data from 55 patients treated with cisplatin-based IP perioperative chemotherapy with (n=26) or without (n=29) epinephrine were analysed using NONMEM.Results:Epinephrine halves clearance between peritoneum and serum (IPCL) and increases the Pt central volume of distribution, IP exposure and penetration in tissue. IPCL has a better predictive value than any other parameter with respect to renal toxicity.Conclusion:This confirms that IPCL could be useful in assessing renal toxicity. As IPCL is also linked to tissue penetration and IP exposure, it may be proposed as biomarker. In addition to a Bayesian estimation, we propose a single-sample calculation-way to assess it. Prospective studies are needed to validate IPCL as a biomarker in this context.

Effect of free volume hole-size on fluid ingress of glassy epoxy networks

This manuscript demonstrates the synthesis of glassy polymer network isomers to control morphological variations and study solvent ingress behavior independent of chemical affinity. Well-controlled network architectures with varying free volume average hole-sizes have been shown to substantially influence solvent ingress within glassy polymer networks. Bisphenol-A diglycidyl ether (DGEBA), bisphenol-F diglycidyl ether (DGEBF) and tetraglydicyl-4,4′-diamino-diphenyl methane (TGDDM) were cured with 3,3′- and 4,4′-diaminodiphenyl sulfone (DDS) at a stoichiometric ratio of 1:1 oxirane to amine active hydrogen to generate a series of network architectures with an average free volume hole-size (Vh) ranging between 59 and 82 Å3. Polymer networks were exposed to water and a broad range of organic solvents ranging in van der Waals (vdW) volumes from 18 to 88 Å3 for up to 10,000 h time. A clear relationship between glassy polymer network Vh and fluid penetration has been established. As penetrant vdW volume approached Vh uptake kinetics significantly decreased, and as penetrant vdW volume exceeded Vh a blocking mechanism dominated ingress and prevented penetrant transport. These results suggest that reducing the free volume hole-size is a reasonable approach to control solvent properties for glassy polymer networks.

Anisotropic diffusion in confined colloidal dispersions: The evanescent diffusivity

We employ an analogy to traditional dynamic light scattering to describe the inhomogeneous and anisotropic diffusion of colloid particles near a solid boundary measured via evanescent wave dynamic light scattering. Following this approach, we generate new expressions for the short-time self- and collective diffusivities of colloidal dispersions with arbitrary volume fraction. We use these expressions in combination with accelerated Stokesian dynamics simulations to calculate the diffusivities in the limit of large and small scattering wave numbers for evanescent penetration depths ranging from four particle radii to one-fifth of a particle radius and volume fractions from 10% to 40%. We show that at high volume fractions, and larger penetration depths, the boundaries have little effect on the dynamics of the suspension parallel to the wall since, to a first approximation, the boundary acts hydrodynamically much as another nearby particle. However, near and normal to the wall, the diffusivity shows a strong dependence on penetration depth for all volume fractions. This is due to the lubrication interactions between the particles and the boundary as the particle moves relative to the wall. These results are novel and comprehensive with respect to the range of penetration depth and volume fraction and provide a complete determination of the effect of hydrodynamic interactions on colloidal diffusion adjacent to a rigid boundary.

Comparing MTA and Ketac Molar Easymix for Furcation Perforation Repair using a Volumetric Method

Aim: We compared the ability of mineral trioxide aggregate (MTA) and Ketac Molar Easymix (KM) to repair furcal perforations in extracted human molars, based on the volume of methylene blue dye penetration.&#x0D; Methodology: In total, 44 human mandibular molars were divided randomly into two (n = 20 each) experimental groups, with two teeth used as positive controls and two teeth without perforations used as negative controls. Group 1 was repaired with MTA and group 2 with Ketac Molar Easymix. The volumetric determination of dye penetration was based on the molecular characteristics of methylene blue. The standard area of a methylene blue particle is known and the surface area can be calculated. We converted the dye penetration area into a volume and performed quantitative analyses.&#x0D; Results: Volume measurement using the dye penetration method showed that KM resulted in more microleakage than MTA (p &lt; 0.05).&#x0D; Conclusions: Mineral trioxide aggregate resulted in significantly less dye leakage than Ketac Molar Easymix using a volumetric measurement method.&#x0D; &#x0D; How to cite this article: Kaya S, Ganidağlı Ayaz S, Doğan MS, Aydın H. Comparing MTA and Ketac Molar Easymix for furcation perforation repair using a volumetric method. Int Dent Res 2011;1:13-17.&#x0D;

Comparison of Dye Extraction or Dye Penetration Methods to Quantitatively Determine Microleakage of Three Different Root Canal Sealers

Aim: This study investigated the feasibility of an approach to determine the volume of dye penetration using methlene blue as dye in comparison to a well known dye extraction method. Materials and methods: One hundred and fifty teeth were randomly divided into two groups (dye extraction or dye penetration methods) of 75 teeth. After, 75 teeth were divided into 3 subgroups for three different root canal sealers. For the volumetric analysis of dye penetration method area of penetration was converted into volume and quantitative analysis was performed. For the dye extraction method dye concentration in the solution was analyzed using an UV-spectrophotometer. In both techniques roots were evacuated prior to dye introduction to prevent air entrapments providing reliable results. The sealabilities of the root canal sealers Ketac-Endo, MetaSEAL, and AH Plus JET were evaluated and results were compared regarding dye extraction or dye penetration methods. Furthermore, 36 teeth were used as positive and negative controls. Results: Dye extraction and volume measurement of dye penetration methods showed that Ketac-Endo displayed the highest apical leakage, followed by MetaSEAL (P 0.05). Conclusions: This study showed that results of volumetric determination of dye penetration method were not different when compared with the results of dye extraction method with vacuuming. In simplifing the procedures, dye extraction method may be preferred.

EVOLUTION OF NEEDLE-FREE MICRO-INJECTION TO THE SOFT SOLID MATERIAL FOR MEDICAL DELIVERY

The evolutions and mechanisms of micro-jet penetration into the solid soft material are described in this paper. The diameter of the micro injector is 300µm. We use the gelatin gel as the solid soft material and water as the injection fluid. Experimental results show that the penetration processes can be described by three phases. I. Induction phase: this phase covers the penetration process of the skin layer. This period lasts only a very short time depending on the power of the micro jet. II. Break phase: This phase covers the penetration process of the inner layer. The volume of jet penetration grows dramatically in this period. III. Saturation phase: The saturation condition was attained when the penetration depth was found to be fixed with time. It is also found that the penetration rate increased linearly with the injection power. It can be fitted in a line with slope of 0.04. It indicates that the stress work of the soft solid is proportional to the injection power. The characteristics can be used to determine the strength of the soft solid materials by jet injection. These data are useful in the needle-free injection for the drug delivery with the endoscope system.

Biodegradation of Resin-Dentin Interfaces Increases Bacterial Microleakage

Bis-GMA-containing resin composites and adhesives undergo biodegradation by human-saliva-derived esterases, yielding Bis-hydroxy-propoxy-phenyl-propane (Bis-HPPP). The hypothesis of this study is that the exposure of dental restorations to saliva-like esterase activities accelerates marginal bacterial microleakage. Resin composites (Scotchbond, Z250, 3M) bonded to human dentin were incubated in either buffer or dual-esterase media (pseudocholinesterase/cholesterol-esterase; PCE+CE), with activity levels simulating those of human saliva, for up to 90 days. Incubation solutions were analyzed for Bis-HPPP by high-performance liquid chromatography. Post-incubation, specimens were suspended in a chemostat-based biofilm fermentor cultivating Streptococcus mutans NG8, a primary species associated with dental caries, for 7 days. Bacterial microleakage was assessed by confocal laser scanning microscopy. Bis-HPPP production and depth and spatial volume of bacterial cell penetration within the interface increased with incubation time and were higher for 30- and 90-day PCE+CE vs. buffer-incubated groups, suggesting that biodegradation can contribute to the formation of recurrent decay.

Development and validation of a high performance liquid chromatography method to determine linezolid concentrations in pig pulmonary tissue

Linezolid is the first synthetic compound of a new group of antimicrobials, the oxazolidinones, which inhibit protein synthesis. It shows a broad spectrum of activity against Gram positive organisms. With respect to its pharmacokinetics, linezolid shows a relatively high volume of distribution and good penetration into inflammatory fluids, bone, fat and muscle. A reversed-phase isocratic high-performance liquid chromatographic method for linezolid analysis in piglet pulmonary tissue is described. Tissue samples and controls were prepared in 1 x TBE (1 M Tris, 0.9 M boric acid, 0.01 M EDTA). The mobile phase consisted of 20% ultrafiltered water and 80% of (A) 15 mM potassium monohydrogen phosphate buffer (pH = 5) with (B) acetonitrile (80%/20%; v/v). Samples were homogenized and precipitated with HClO(4) 3% (1/1, v/v). The injection volume was 100 microL. Ofloxacin was used as an internal standard. The assay was linear over a linezolid concentration range: 1.6-100 microg/mL. The method provided good validation data (n = 15): inaccuracy (3.6%), intra and inter-day variability (4.2% and 5.2%, respectively), recovery (91.8%), limit of detection (0.8 microg/mL) and quantitation (1.6 microg/mL) and acceptable stability within 24 h in the auto-sampler. The method offers a fast and simple approach to determine linezolid in pulmonary tissue which could be of use in pharmacokinetic studies.

Gas and water vapor permeation in a short-side-chain PFSI membrane

The gas and vapor transport into films of Hyflon® Ion H, a short-side-chain perfluorosulfonic acid ionomeric (PFSI) membrane, suitable for use in proton exchange membrane fuel cells (PEMFC), has been studied at various temperatures (35°C, 50°C, and 65°C). The permeability and diffusivity values of He, N 2, and O 2 show an Arrhenius type dependence on temperature in the range inspected. Pure water vapor permeation was studied at 65°C, at low/medium activity values. The determination of water transport parameters has been performed by solving numerically the water mass balance with a variable diffusion coefficient and accounting for a water immobilization reaction onto the hydrophilic sites of the matrix. The boundary conditions vary in time according to the mass balance on the penetrant volume. The solution allows to represent closely the experimental permeation behavior in all its stages.

Longitudinal distribution of ozone absorption in the lung: Comparison of cigarette smokers and nonsmokers

In nonsmokers, ozone (O 3) is removed primarily by the epithelial lining fluid (ELF) of the conducting airways. We hypothesized that cigarette smokers, whose ELF antioxidant capacity may be limited by smoking, would remove less O 3 from their conducting airways than nonsmokers. We recruited 29 nonsmokers (17M, 12F) and 30 smokers (19M, 11F, 4 ± 4 pack-years) with similar anthropometric characteristics and measured the longitudinal distribution of O 3 using the bolus inhalation method. We also assessed the physiological effect of this transient exposure regimen using forced spirometry and capnography. Contrary to our hypothesis, the penetration volume at which 50% of a bolus was absorbed was not different between smokers and nonsmokers (97.1 ± 5.4 mL versus 97.9 ± 5.8 mL, p = 0.92). However, smokers did experience an increase in the slope of the alveolar plateau of the capnogram ( S N) (8.1 ± 3.2%, p = 0.02) and a small decrease in FEV 1 (− 1.3 ± 0.6%, p = 0.03), whereas nonsmokers did not (ΔFEV 1 − 0.1 ± 0.5% and Δ S N − 0.2 ± 2.5%, p > 0.10). Thus, smokers are more sensitive to inhaled O 3 boluses than nonsmokers, despite a similar internal dose distribution.

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