Absorbent Foam Research Articles

Automation of liquid removal from natural gas wells

Water and other liquids can cause production problems for natural gas wells. An established but labour-intensive method for removing these liquids is the use of absorbent foam sticks, which are lowered into the wells and then lifted back up again. This paper presents an automated solution for launching foam sticks down gas wells and recovering them – and without the need for a grid electricity supply. The foam-stick launching apparatus has an enclosed magazine with several chambers. It is controlled by a solar-powered skid-mounted electric–pneumatic control system, which includes a storage battery, time relays, a wireless switch module and a compressed gas supply. A typical water-producing gas well was selected to illustrate the technology. Its successful application indicates that engineers can remove liquid from water-producing gas wells and bring them back to production normally using this novel artificial lift technology, which can also be used in remote areas with no electrical supply.

Young Investigator Challenge: A novel, simple method for cell block preparation, implementation, and use over 2 years.

The cell block is an essential adjunct to conventional cytopreparatory techniques. The need for molecular analysis and immunostains will increase the need for successful cell block preparation. Even with this need, to the authors' knowledge very little has changed regarding the way in which cell blocks are produced. The authors developed A Formalin-Fixed, paraffin Embedded Cytology cell block Technique (AFFECT) that uses a cytospin centrifuge and funnel to deposit a cell pellet into a well on a piece of open-cell, absorbent foam. The foam and the pellet are then sent through normal processing. Herein, the authors present the implementation of this method and some of their experience with its performance over the course of 2 years. Although a comparison of the methods indicated good correlation for the production of a cell block between AFFECT and the agarose method, the AFFECT blocks demonstrated markedly improved cellular morphology. Over the first 6 months of use, AFFECT produced a successful cell block in 74% of cases overall, and in 65% of cases with a cell pellet measuring ≤0.1 mL. The year preceding the implementation of AFFECT and its first year of use were compared for endoscopic and bronchoscopic ultrasound-guided fine-needle aspiration specimens, and demonstrated an improved success rate. The authors developed a novel method of cell block preparation that demonstrates improved histology and has increased the success rate of cell block production compared with the agarose method. Cancer Cytopathol 2016;124:885-892. © 2016 American Cancer Society.

<i>In Vitro</i> Cytotoxicity Evaluation of Highly Absorbent Foam Dressings Based on Silver Zirconium Phosphate via IC<sub>50</sub> Value

In this study, we, for the first time, tried to apply IC50 values (inhibitory concentration estimated to affect the endpoint in question by 50%) in the MTT colorimetric assay to investigate the cytotoxic effects of highly absorbent foam dressings based on silver zirconium phosphate, a newly nano-based matrix. Our results showed that silver released from dressings based on silver zirconium phosphate attributed mainly to highly cytotoxic to L929 cells cultured with MEM containing 10% fetal bovine serum. In addition, we have also compared the IC50 values among different dilutions of AgNO3 solution, silver based dressing extracts and material reference control (ZDEC) extracts using the optimized MTT assay, along with characterizing the silver content in the dressing extracts using atomic absorption spectroscopy. Results have shown that the IC50 values of AgNO50 solution, silver based dressing extracts and ZDEC extracts are 3.5 μg/mL, 3.8 μg/mL and 8.4%, respectively. And there exist some good agreements between qualitative and quantitative evaluation method as well. In conclusion, our study has led to the view that the IC50 value is a promising quantitative index for screening cytotoxicity with regard to silver based dressings.

Attenuation of a hydrogen-air detonation by acoustic absorbing covering

Using of sound-absorbing surfaces to weaken and decay of a detonation wave in hydrogen-air mixtures was investigated experimentally. Experiments were carried out in a cylindrical detonation tube open at one end. Initiation of the explosive mixture was carried out by a spark discharge, which is located at the closed end of the detonation tube. Acoustical sound absorbing foam element of a specific weight of 0.035 g/cm3 with open pores of 0.5 mm was used. The degree of attenuation of the intensity of the detonation wave front was determined.

Safety assessment of sanitary pads with a polymeric foam absorbent core

Sanitary pads for menstrual hygiene have a layered design consisting of a fluid permeable surface (topsheet), an absorbent core, and an impermeable backing with adhesive. Most sanitary pads employ cellulose-based cores. This describes the safety evaluation of a menstrual pad with an emollient-treated topsheet and a novel polymeric foam core. A quantitative risk assessment was performed, which included: (1) toxicological evaluation of the raw material components; (2) quantitative exposure assessments of pad constituents, accounting for the fluid handling properties of the product and pertinent conditions of use; and (3) risk characterization for exposure to raw materials (e.g., potential for skin irritation, contact sensitization, or systemic effects, if relevant) and to the physical article itself (potential effects on skin friction, etc.). No significant risk of adverse effects was found. Five years of post-market surveillance substantiates that the product is well-tolerated (1 health complaint reported per 2 million products shipped to market) and surpasses women's expectations for menstrual protection and overall comfort and dryness. This report illustrates how the classical risk assessment paradigm, informed by the impact of product design, functionality and pertinent use conditions, allowed the systematic safety evaluation of a personal hygiene product with a novel, non-cellulosic absorbent foam core technology.

Blast performance of water tank with energy absorbing support

The blast performance of water tank with an innovative energy absorbing support was studied to reduce the support reaction force and mitigate the damage on the water tank. The aluminum foam was adopted as the energy absorbing material, since it has high energy absorbing potential during crush plateau and safety backup zone after the compaction strain. Finite element model considering fluid and structural interaction in which the water is modeled using the Eulerian formulation and the steel tank by Lagrangian formulation is proposed. The proposed numerical model of water tank was verified by comparing the predicted results with the test results obtained from dynamic pressure tests on steel tanks filled with water. The numerical results showed that the support reaction force depends on the density and yield strength of the aluminum foams and the reaction force could be reduced significantly if softer aluminum foam was chosen. The total displacement of the water tank was increased by up to 38% due to the increase in deformation of the energy absorbing foam. The aluminum foam was proposed to absorb the blast energy and reduce the damage on the water tank. However, more damage on the water tank was observed when a very low density aluminum foam support was used. This was attributed to the increased external work done by blast loading which was higher than the energy absorbed by the aluminum foam support.

A simple preparation method and characterization of epoxy reinforced microporous phenolic open-cell sound absorbent foam

A series of micro-porous phenolic open-cell sound absorbent foams reinforced by epoxy resin were fabricated by a physical foaming method.

Properties of Absorbent Acrylic Foam Prepared Based on the Method of High Internal Phase Emulsion

Acrylate and methacrylate monomers absorbent acrylate foams were prepared based on the method of high internal phase emulsion (HIPE). The influence of reaction conditions on liquid absorption by acrylate foams was studied. The reaction conditions included monomer ratio, cross-linker amount, initiator amount, emulsifier amount, emulsion concentration, emulsification temperature, and the curing time. The reaction conditions were determined to achieve the best liquid absorption by acrylate foams. Acrylate foams were analyzed with Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results showed that when the monomer ratio was 9:1, cross-linking agent was 30% of monomer amount, initiator amount was 4% of the reactants amount, emulsifier amount was 8% of the reactants amount, the ratio of aqueous phase to oil phase was 32:1, emulsification temperature was 75°C, and curing time was 1.5 h, we could prepare the acrylate foam material with the best liquid absorption. Reaction of monomer and cross-linking agent was confirmed by FTIR analysis. The pore sizes of acrylate foam were between 1 μm and 8 μm according to SEM analysis. This material was very suitable to absorb aqueous fluids.

Retention of polyurethane foam fragments during VAC therapy: a complication to be considered

Vacuum-assisted closure (VAC) therapy is a closed-loop, non-invasive active system, characterised by a controlled and localised negative pressure applied on porous polyurethane absorbent foams. It promotes healing of acute and chronic wounds. Therapeutic effects of VAC therapy have been proved and demonstrated; however, this method can have some disadvantages. Even if it is a quite versatile device, only qualified medical/paramedical personnel should use it in order to avoid possible complications that can occur after an improper application. In this report, 11 cases of foam-fragment retention within the wound are presented. This rare complication did not promote healing, but further hindered it. On the basis of our experience, it is mandatory to define the indications, benefits and limitations of VAC therapy.

Examination of a Properly Restrained Motorsport Occupant

Throughout the first decade of the twenty first century, large improvements in occupant safety have been made in NASCAR®'s (National Association for Stock Car Auto Racing, Inc) race series. Enhancements to the occupant restraint system include the implementation and advancement of head and neck restraints (HNR), minimum performance requirements for belts and seats and the introduction of energy absorbing foam are a few highlights, among others. This paper summarizes three non-injury case studies of actual on-track incidents, including the acceleration pulses, principal direction of force, restraint systems used and driver anthropometry information. Also discussed are the NASCAR personal safety equipment requirements as well as frontal, oblique and side sled testing data of similar input acceleration magnitudes for the Hybrid III (H-III) fiftieth percentile male anthropomorphic test device (ATD). Language: en

Preparation of Absorbent Foam Based on Softwood Kraft Pulp: Advancing from Gram to Kilogram Scale

Absorbent foams were produced at both the gram scale and the kilogram scale by treating bleached softwood kraft pulp fibers to TEMPO oxidation, followed by washing, fiber disintegration, and freeze drying. Two reaction temperatures and three different dosages of primary oxidant were evaluated to find suitable oxidation conditions. It was found that the absorption and retention capacities were 50 to 70% lower for kilogram-scale foams than for gram-scale foams. SEM studies showed that the kilogram-scale foams had larger pores than the gram-scale foams; this explains the major differences in absorption and retention. The oxidation treatments performed in both scales resulted in a major increase in the amount of carboxylate groups and a major decrease in DPV, but only minor differences in these factors were found in a comparison between pulps from gram-and kilogram-scale experiments. However, the kilogram-scale dispersing equipment appeared to cause more fiber cutting, while the equipment used in the gram-scale experiments promoted the liberation of microfibrils to a greater extent. Furthermore, in both the gram- and kilogram-scale samples, a high dosage of primary oxidant and a low oxidation temperature were found to maximize the retention of liquid.

Correlation between the acoustic and porous cell morphology of polyurethane foam: Effect of interconnected porosity

Interconnected pore cell in appropriately chosen porous media can help to enhance their sound absorption performance. Acoustic absorbing foam materials were produced from polyurethane (PU) with addition of water as a blowing agent and OR-501 as open pore cell agent. The pore sizes of the foams were varied from 0.35 to 1.05mm in diameter and the pore cells were interconnected with open porosity in the range from 16.0% to 88.6%. The compressive strength of the foams decreased with increase of interconnected cell ratios. There was a decrease of the strength lower than 92.6% compared to the closed cell sample when interconnected cell ratio was 88.6%. The acoustical efficiencies of PU foams were studied, and the results showed that the porous cell size and interconnected porosity of PU foams had significant influence on the acoustical efficiencies. Significant enhancements of the absorption properties could be obtained over a low frequency band by increasing the interconnected porous cell. The absorption coefficient of the interconnected cell foam was 0.66 at low frequency of 250–600Hz with an increase of 100% compared to the closed-cell ones. The internal transmission path and loss mechanism of noise in the porous polyurethane materials were also analyzed in the present work.

Reinforced absorbent material: a cellulosic composite of TEMPO-oxidized MFC and CTMP fibres

This research aims to develop new materials based on renewable resources that can fulfill the functions necessary in the absorption core of a disposable diaper. Absorbent foam was recently produced from softwood kraft pulp by TEMPO oxidation, disintegration and freeze drying. In this study, the TEMPO-oxidized MFC was mixed with pulp fibres, thus forming a cellulosic composite, in an attempt to improve the mechanical stability of the freeze-dried absorbent material. The fibres were added in different amounts and the freeze-dried materials were evaluated for their absorption and retention properties. The results of this study suggest that the composite material has a better mechanical stability than the absorbent foam without fibres. It was shown that using spruce CTMP fibres in the composite resulted in better absorption and retention capacities than in a composite with softwood kraft pulp fibres. The higher stiffness of the CTMP fibres is a probable explanation for this difference. For the composite material with CTMP fibres, liquid porosimetry showed that pore size distribution was more or less retained when put under load. Furthermore, it was seen that the retention properties reached a maximum around 85 % CTMP fibres and 15 % TEMPO-oxidized MFC. In the centrifuge retention test, the retention of the TEMPO-oxidized MFC in the composite material reached about the same capacity as conventional superabsorbent polymers.

Improve Lower Leg Impact Performance Considering Pedestrian Protection

To improve the lower leg impact performance of the vehicle bumper in the collision of vehicle to pedestrian, the finite element (FE) model of a vehicle front structure was developed, and correlated with the test results. The lower legform impactor FE model was used to investigate the performance of the vehicle bumper at different structure conditions. It was finally determined that vehicle to lower legform impact performance can be improved by reducing the energy absorbing foam stiffness and modifying the bumper bracket structure to enlarge the collapse space.

A displacement-pressure finite element formulation for analyzing the sound transmission in ducted shear flows with finite poroelastic lining

In the present work, the propagation of sound in a lined duct containing sheared mean flow is studied. Walls of the duct are acoustically treated with absorbent poroelastic foams. The propagation of elasto-acoustic waves in the liner is described by Biot's model. In the fluid domain, the propagation of sound in a sheared mean flow is governed by the Galbrun's equation. The problem is solved using a mixed displacement-pressure finite element formulation in both domains. A 3D implementation of the model has been performed and is illustrated on axisymmetric examples. Convergence and accuracy of the numerical model are shown for the particular case of the modal propagation in a infinite duct containing a uniform flow. Practical examples concerning the sound attenuation through dissipative silencers are discussed. In particular, effects of the refraction effects in the shear layer as well as the mounting conditions of the foam on the transmission loss are shown. The presence of a perforate screen at the air-porous interface is also considered and included in the model.

New methods to quantify NH3 volatilization from fertilized surface soil with urea

Gaseous N losses from soil are considerable, resulting mostly from ammonia volatilization linked to agricultural activities such as pasture fertilization. The use of simple and accessible measurement methods of such losses is fundamental in the evaluation of the N cycle in agricultural systems. The purpose of this study was to evaluate quantification methods of NH3 volatilization from fertilized surface soil with urea, with minimal influence on the volatilization processes. The greenhouse experiment was arranged in a completely randomized design with 13 treatments and five replications, with the following treatments: (1) Polyurethane foam (density 20 kg m-3) with phosphoric acid solution absorber (foam absorber), installed 1, 5, 10 and 20 cm above the soil surface; (2) Paper filter with sulfuric acid solution absorber (paper absorber, 1, 5, 10 and 20 cm above the soil surface); (3) Sulfuric acid solution absorber (1, 5 and 10 cm above the soil surface); (4) Semi-open static collector; (5) 15N balance (control). The foam absorber placed 1 cm above the soil surface estimated the real daily rate of loss and accumulated loss of NH3N and proved efficient in capturing NH3 volatized from urea-treated soil. The estimates based on acid absorbers 1, 5 and 10 cm above the soil surface and paper absorbers 1 and 5 cm above the soil surface were only realistic for accumulated N-NH3 losses. Foam absorbers can be indicated to quantify accumulated and daily rates of NH3 volatilization losses similarly to an open static chamber, making calibration equations or correction factors unnecessary.

Experimental study of a smart foam sound absorber

This article presents the experimental implementation and results of a hybrid passive/active absorber (smart foam) made up from the combination of a passive absorbent (foam) and a curved polyvinylidene fluoride (PVDF) film actuator bonded to the rear surface of the foam. Various smart foam prototypes were built and tested in active absorption experiments conducted in an impedance tube under plane wave propagation condition at frequencies between 100 and 1500 Hz. Three control cases were tested. The first case used a fixed controller derived in the frequency domain from estimations of the primary disturbance at a directive microphone position in the tube and the transfer function between the control PVDF and the directive microphone. The two other cases used an adaptive time-domain feedforward controller to absorb either a single-frequency incident wave or a broadband incident wave. The non-linearity of the smart foams and the causality constraint were identified to be important factors influencing active control performance. The effectiveness of the various smart foam prototypes is discussed in terms of the active and passive absorption coefficients as well as the control voltage of the PVDF actuator normalized by the incident sound pressure.

Laboratory findings on the exudate-handling capabilities of cavity foam and foam-film dressings

To compare the fluid-handling properties of a range of commonly used absorbent foam dressings. Results were analysed to generate broad estimates of wear time, using previously published data for the rate at which exudate is produced by various wound types. Test data were produced by an independent, accredited test facility using a series of standard test systems, and submitted to the author for review and interpretation. Absorbency values for the cavity foam dressings tested ranged from 11 to 16 grams per 10cm(2) sample under the specified test conditions. The increase in dressing volume ranged from 71% to 206%, although this did not always correlate directly with absorbency values. Foam-film dressing tests revealed large variations in product performance. The total fluid handling capacity of dressings (the sum of absorbency and evaporative loss) ranged from approximately 7 to 26 grams per sample. These differences are largely due to variations in permeability of the film backing layer, which ranged from approximately 2000 to 20,000g/m(2)/24h. Compression reduced the absorbency of most dressings but it appeared to enhance the performance of one product (possibly through ensuring contact between the test sample and the simulated wound bed). 9 of the 11 sheet dressings tested were estimated to be capable of managing normal levels of wound exudate for 48 hours, based solely on their absorbency figures. Considering the additional effects of moisture vapour permeability, theoretical wear time increases to five days in a number of instances. The laboratory data suggest considerable differences in the clinical performance of dressings. Making a number of assumptions as stated in the text, predicted values for clinical performance were generated. These estimates show marked differences between dressings. This report was produced by the author for a professional fee, from BSN, as a medical device consultant and medical writer using test data generated independently by an accredited laboratory. The author had no involvement either with the choice of test methods, or the range of dressings included in the study, and has no financial interests in any of the products concerned.

A Disposable Tear Glucose Biosensor--Part 2: System Integration and Model Validation

We presented a concept for a tear glucose sensor system in an article by Bishop and colleagues in this issue of Journal of Diabetes Science and Technology. A unique solution to collect tear fluid and measure glucose was developed. Individual components were selected, tested, and optimized, and system error modeling was performed. Further data on prototype testing are now provided. An integrated fluidics portion of the prototype was designed, cast, and tested. A sensor was created using screen-printed sensors integrated with a silicone rubber fluidics system and absorbent polyurethane foam. A simulated eye surface was prepared using fluid-saturated poly(2-hydroxyethyl methacrylate) sheets, and the disposable prototype was tested for both reproducibility at 0, 200, and 400 microM glucose (n = 7) and dynamic range of glucose detection from 0 to 1000 microM glucose. From the replicated runs, an established relative standard deviation of 15.8% was calculated at 200 microM and a lower limit of detection was calculated at 43.4 microM. A linear dynamic range was demonstrated from 0 to 1000 microM with an R(2) of 99.56%. The previously developed model predicted a 14.9% variation. This compares to the observed variance of 15.8% measured at 200 microM glucose. With the newly designed fluidics component, an integrated tear glucose prototype was assembled and tested. Testing of this integrated prototype demonstrated a satisfactory lower limit of detection for measuring glucose concentration in tears and was reproducible across a physiological sampling range. The next step in the device design process will be initial animal studies to evaluate the current prototype for factors such as eye irritation, ease of use, and correlation with blood glucose.

Calculable blackbody radiation as a source for the determination of the spectral responsivity of THz detectors

The spectral responsivity of the detector is important for the layout and quantitative interpretation of spectroscopic experiments. In the terahertz (THz) spectral range the knowledge of the total (integral) responsivity of a detector, as well as its spectral distribution, is often insufficient. PTB determined the spectral irradiance responsivity of two THz detectors, a pyroelectric DLATGS detector working at room temperature and a silicon-composite bolometer working at 4 K, in the wavelength range from 62 µm (4.82 THz) to 1340 µm (0.22 THz) with temperature radiation from blackbody radiators. Our approach is to use two THz cavity radiators in combination with THz bandpass filters to provide calculable spectral irradiances, according to Planck's law of radiation, at several wavelength bands in the THz spectral range. One cavity radiator is working at an adjustable fixed temperature in the range from 15 °C to 90 °C while the other cavity radiator operates at LN2 temperature. The radiation of the two cavity radiators is alternately imaged on the detector via a gold-coated chopper wheel. Hereby the background radiation is cancelled and also the necessary modulation for the lock-in detection is provided. The cavity of the high temperature radiator is coated with a dedicated paint providing high wall emissivity in the FIR and THz spectral range to ensure true blackbody behaviour of the radiator. The bottom of the low temperature radiator consists of THz absorber foam providing hereby also nearly blackbody behaviour. All individual filters and, additionally, the employed filter combinations are characterized for their transmittance in the entire wavelength range from 0.8 µm to 1700 µm to obtain a precise knowledge of the transmitted blackbody spectrum. The very reproducible results indicate that this setup allows a fast, simple and reliable determination of the spectral responsivity of THz detectors. In a next step, the uncertainty of this technique will be further evaluated and investigations will be extended to other types of detectors (e.g. LiTaO3 detectors and Golay cells).