Experimental study of CO2 injectivity impairment in sandstone due to salt precipitation and fines migration

Re-injection of carbon dioxide (CO2) in deep saline formation is a promising approach to allow high CO2 gas fields to be developed in the Southeast Asia region. However, the solubility between CO2 and formation water could cause injectivity problems such as salt precipitation and fines migration. Although both mechanisms have been widely investigated individually, the coupled effect of both mechanisms has not been studied experimentally. This research work aims to quantify CO2 injectivity alteration induced by both mechanisms through core-flooding experiments. The quantification injectivity impairment induced by both mechanisms were achieved by varying parameters such as brine salinity (6000–100,000 ppm) and size of fine particles (0–0.015 µm) while keeping other parameters constant, flow rate (2 cm3/min), fines concentration (0.3 wt%) and salt type (Sodium chloride). The core-flooding experiments were carried out on quartz-rich sister sandstone cores under a two-step sequence. In order to simulate the actual sequestration process while also controlling the amount and sizes of fines, mono-dispersed silicon dioxide in CO2-saturated brine was first injected prior to supercritical CO2 (scCO2) injection. The CO2 injectivity alteration was calculated using the ratio between the permeability change and the initial permeability. Results showed that there is a direct correlation between salinity and severity of injectivity alteration due to salt precipitation. CO2 injectivity impairment increased from 6 to 26.7% when the salinity of brine was raised from 6000 to 100,000 ppm. The findings also suggest that fines migration during CO2 injection would escalate the injectivity impairment. The addition of 0.3 wt% of 0.005 µm fine particles in the CO2-saturated brine augmented the injectivity alteration by 1% to 10%, increasing with salt concentration. Furthermore, at similar fines concentration and brine salinity, larger fines size of 0.015 µm in the pore fluid further induced up to three-fold injectivity alteration compared to the damage induced by salt precipitation. At high brine salinity, injectivity reduction was highest as more precipitated salts reduced the pore spaces, increasing the jamming ratio. Therefore, more particles were blocked and plugged at the slimmer pore throats. The findings are the first experimental work conducted to validate theoretical modelling results reported on the combined effect of salt precipitation and fines mobilisation on CO2 injectivity. These pioneering results could improve understanding of CO2 injectivity impairment in deep saline reservoirs and serve as a foundation to develop a more robust numerical study in field scale.

Management of validation of HPLC method for determination of acetylsalicylic acid impurities in a new pharmaceutical product

The work mainly focused on a validation of the method for determining the content of salicylic acid and individual unknown impurities in new pharmaceutical product—tablets containing: 75, 100 or 150 mg of acetylsalicylic acid and glycine in the amount of 40 mg for each dosage. The separation of the components was carried out by means of HPLC, using a Waters Symmetry C18 column (4.6 × 250 mm, 5 μm) as the stationary phase. The mobile phase consisted of a mixture of 85% orthophosphoric acid, acetonitrile and purified water (2:400:600 V/V/V). Detection was carried out at a wavelength of 237 nm, with a constant flow rate of 1.0 ml min−1. In order to verify the method, linearity, precision (repeatability and reproducibility), accuracy, specificity, range, robustness, system precision, stability of the test and standard solution, limit of quantification and forced degradation were determined. Validation tests were performed in accordance with ICH (International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use) guidelines. The method was validated successfully. It was confirmed that the method in a tested range of 0.005–0.40% salicylic acid with respect to acetylsalicylic acid content is linear, precise and accurate.

Improving the Hydraulic Effects Resulting from the Use of a Submerged Biofiter to Enhance Water Quality in Polluted Streams

Water scarcity is one of the most serious problems facing many countries. In addition, water pollution could lose more water. A submerged biofilter (SB) is used to enhance the self-purification process in polluted streams. However, most previous studies have focused on the efficiency of SB to remove pollutants and there is a lack of studies investigating the hydraulic changes in streams. The current paper aimed to study the hydraulic effects of SB on the flow behavior in streams and how to improve it. An empirical equation for determining the flow rate through SB was developed. Different cases were studied to improve the hydraulic effects resulting from the use of SB. The effect of increasing SB length was tested using different SB lengths. The results showed that increasing the length increased the upstream water depth (h1) and relative heading up (h1/h2). In the second case, comparison between continuous and fragmented SB was tested. The results showed that a fragmented biofilter increased the upstream water depth and the relative heading up. Case three tested the effect of SB height. Different SB heights were tested with a fixed length and constant flow rate. The results revealed that the upstream water depth and relative heading up decreased when the biofilter height decreased. Case four tested the effect of SB with a fixed volume and constant flow rate. In this case, the length and height of SB were changed where the volume was fixed. The results showed that the relative heading up decreased when the SB height decreased and the length increased, which revealed that the SB height can improve the hydraulic impacts. Finally, the use of SB to improve the water quality in polluted streams led to an increase of the relative heading up, which can be reduced by decreasing the height of SB.

Excipient-Free Inhalable Microparticles of Azithromycin Produced by Electrospray: A Novel Approach to Direct Pulmonary Delivery of Antibiotics

Inhalation therapy offers several advantages in respiratory disease treatment. Azithromycin is a macrolide antibiotic with poor solubility and bioavailability but with a high potential to be used to fight lung infections. The main objective of this study was to generate a new inhalable dry powder azithromycin formulation. To this end, an electrospray was used, yielding a particle size around 2.5 µm, which is considered suitable to achieve total deposition in the respiratory system. The physicochemical properties and morphology of the obtained microparticles were analysed with a battery of characterization techniques. In vitro deposition assays were evaluated after aerosolization of the powder at constant flow rate (100 L/min) and the consideration of the simulation of two different realistic breathing profiles (healthy and chronic obstructive pulmonary disease (COPD) patients) into a next generation impactor (NGI). The formulation was effective in vitro against two types of bacteria, Staphylococcus aureus and Pseudomonas aeruginosa. Finally, the particles were biocompatible, as evidenced by tests on the alveolar cell line (A549) and bronchial cell line (Calu-3).

Net Water Drag Coefficient during High Temperature Operation of Polymer Electrolyte Fuel Cells

For polymer electrolyte fuel cell (PEFC) systems in vehicle applications, net water drag coefficient ( ) is an essential index and must be negative for system operation. The feasibility of PEFC operation at temperatures over 100C was examined here by measuring and comparing the current density (j) - characteristics using PEFCs with either an Aquivion or Nafion membrane. The effect of cell temperature ( ) on was evaluated at range from 80 to 120C. Results clearly demonstrated that, for both membrane types, significantly increased increasing . Results also confirmed that, at a constant flow rate of H2 at the anode, decreased with decreasing stoichiometric ratio of air ( ), although the effect of on was relatively small. Finally, the effect of relative humidity (RH) balance of supplied gases in both sides (anode/cathode) on water transport at temperature up to 120C was examined for the Aquivion cell. Results revealed that could be significantly decreased by decreasing the RH of hydrogen supplied to the anode (RHA) and that the control of RHA is an effective method for lowering at elevated temperature operation.

Dynamic flow and shear stress as key parameters for intestinal cells morphology and polarization in an organ-on-a-chip model

Gut-on-a-chip microfluidic devices have emerged as versatile and practical systems for modeling the human intestine in vitro. Cells cultured under microfluidic conditions experience the effect of shear stress, used as a biomechanical cue to promote a faster cell polarization in Caco-2 cells when compared with static culture conditions. However, published systems to date have utilized a constant flow rate that fails to account for changes in cell shear stress ($${\tau }_{c}$$ τ c ) resulting from changes in cell elongation that occur with differentiation. In this study, computational fluid dynamics (CFD) simulations predict that cells with villi-like morphology experience a $${\tau }_{c}$$ τ c higher than bulge-like cells at the initial growth stages. Therefore, we investigated the use of a dynamic flow rate to maintain a constant $${\tau }_{c}$$ τ c across the experiment. Microscopic assessment of cell morphology and dome formation confirmed the initiation of Caco-2 polarization within three days. Next, adopting our dynamic approach, we evaluated whether the following decreased flow could still contribute to complete cell differentiation if compared with the standard constant flow methodology. Caco-2 cells polarized under both conditions, secreted mucin-2 and villin and formed tight junctions and crypt-villi structures. Gene expression was not impacted using the dynamic flow rate. In conclusion, our dynamic flow approach still facilitates cell differentiation while enabling a reduced consumption of reagents.

Sex-dependent change in the reactivity of isolated pulmonary arteries of gonadectomized rats under the intermittent hypoxia of different degree

Introduction. Pulmonary vasoconstriction is one of factors of hypoxic pulmonary hypertension (HPH). The progression of this disease depends on the degree of hypoxiа and seх. The aim of this study was to investigate the reactivity of isolated pulmonary vessels of male and female rats with HPH to vasoactive factors. Materials and methods. The experiments were on male and female of Wistar rats 190–200 g, which were gonadectomized. All animals were divided into 4 groups. One group of males and female rats was kept in a vivarium (21 % О2 ). To simulate HPH, other rats were exposed to hypobaric hypoxia for 10 hours a day at an oxygen content in the inhaled air equal to 13 % (pP O2 103.7 mmHg) or 10 % (pP O2 78,2 mmHg), or 8 % (pP O2 63,5 mmHg) as compared to its content at 21 % (pP О2 159 mmHg). After that, a third-order pulmonary vessel was perfused at a constant flow rate with vasoconstrictors and vasodilators. The reaction was recorded by the change in perfusion pressure. Results. In females with HРН 10 %O2 , constricting response to serotonin were greater than in males. In normotensive males, the dilatory response to sodium nitroprusside (NP) was less than in female. Exposure to hypoxia induced an increase in NP responses. Conclusion. Increased reactivity of pulmonary vessels to serotonin is a factor of pathogenesis of HPH in females, in contrast to males. Increased reactivity to NO donor in males exposed to hypoxia сan be used for a pharmacological target for HPH.

Influence of HHO Gas Addition on Combustion, Performance and Emission Characteristics of a CI Engine Fuelled with Used Cooking Oil Bio Fuel Blends

The present study is to investigate the influence of used cooking oil (UCO) bio diesel blend and HHO gas on combustion, performance and emission characteristics of a variable compression ratio multi fuel engine. Bio fuel is extracted from UCO through transesterification process. Blends of diesel and UCO bio fuel is used as primary fuel and hydroxyl (HHO) gas which was generated from the electrolysis of water is used as supplementary fuel. Engine was tested for three different fuels such as diesel, B20 blend and B20 +HHO blends by varying four different loads (25%, 50%, 75%, and 100%) at the constant speed of 1500 rpm. HHO gas was injected in to the intake manifold with constant flow rate of 0.5 lpm for all engine loads. Engine fuelled with B20+HHO blends showed better brake thermal efficiency and lower brake specific fuel consumption and emitted less CO and HC emissions over the B20 blends and diesel.

Antioxidant Activity and Bioactive Compounds of Lamium album Flower Extracts Obtained by Supercritical Fluid Extraction

In this research, supercritical CO2 extraction is applied to extract bioactive compounds from Lamium album (white dead nettle, Lamiaceae). Extraction was performed at various temperatures (40, 50, and 60 °C) using methanol as co-solvent at a constant flow rate of CO2, methanol, and pressure. The collected extracts were characterized in terms of antioxidant capacity by using DPPH, ABTS and FRAP in vitro antioxidant activity assays, whereas the Folin–Ciocalteu procedure was employed to estimate the total phenols content (TPC). On the other hand, phenolic compounds in the extracts were quantitated by liquid chromatography coupled with a photodiode array detector (UPLC-PDA) and confirmed with a mass detector (TQD). The extracts have shown high TPC ranged between 234.17 to 650.17 mg GAE/g extract. DPPH scavenging of the extracts was estimated and obtained EC50 values ranged from 0.12 to 0.37 mg/mL of solution. The ABTS radical scavenging activity ranged from 43.20 to 44.53 µg TE/g. The FRAP value was found within the range of 19.48 to 44.74 µmol TE/g of extract. Differences between extraction conditions were observed. In this research, 50 °C/250 bar was efficient for the TPC, DPPH, ABTS, and FRAP assays; moreover, statistically, TPCs and FRAP assay showed significant differences between the conditions at α = 0.05. The identification of phenolic compounds in the obtained extract of Lamium album flowers, using UPLC/PDA, revealed that chrysin, pinostrobin, myricetin, and trans-3-hydroxycinnamic acid were the significant molecules present, which may be responsible for the high content of polyphenols and antioxidant activity. The results obtained indicated that SC-CO2 could be considered an alternative method for extracting bioactive compounds of Lamium album. High antioxidant activity and the presence of various bioactive compounds indicate the potential of this plant from the Lamiaceae family and the possibility of its application in various industries, including agriculture, food technology, or pharmacy.