Displaying publications 81 - 100 of 422 in total

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  1. Siah, W.M., Aminah, A., Ishak, A.
    MyJurnal
    A new patent pending process is proposed in this study to produce edible film directly from seaweed (Kappaphycus alvarezii). Seaweed together with other ingredients has been used to produce the film through casting technique. Physical and mechanical tests were performed on the edible films to examine the thickness, colour, transparency, solubility, tensile strength,
    elongation at break, water permeability rate, oxygen permeability rate and surface morphology. Produced film was transparent, stretchable, sealable and have basic properties as a film for food packaging. This study suggests that the edible film could be used as novel materials in food industry as sachet/pouch/bag for instant coffee, breakfast cereals drinks, seasoning powder,
    candies etc; as wrapper for seasoning cube and chocolate; as interleaf for frozen foods such as burger patties to avoid the patties from sticking together; and also as material for edible logo in bakeries products. Other than that, the edible film also could be used in pharmaceutical industry as functional strips such as oral freshener strips and drug strips. In cosmetic and toiletries industries, the edible film could be used to produce facial mask and bag for pre-portioned detergent. Compared with edible film developed earlier using alginate and carrageenan, film developed in this research used seaweed directly. The developed film reduced the need to extract the alginate and carrageenan, making material preparation easier and cheaper.
    Matched MeSH terms: Solubility
  2. Sheshala R, Anuar NK, Abu Samah NH, Wong TW
    AAPS PharmSciTech, 2019 Apr 15;20(5):164.
    PMID: 30993407 DOI: 10.1208/s12249-019-1362-7
    This review highlights in vitro drug dissolution/permeation methods available for topical and transdermal nanocarriers that have been designed to modulate the propensity of drug release, drug penetration into skin, and permeation into systemic circulation. Presently, a few of USFDA-approved in vitro dissolution/permeation methods are available for skin product testing with no specific application to nanocarriers. Researchers are largely utilizing the in-house dissolution/permeation testing methods of nanocarriers. These drug release and permeation methods are pending to be standardized. Their biorelevance with reference to in vivo plasma concentration-time profiles requires further exploration to enable translation of in vitro data for in vivo or clinical performance prediction.
    Matched MeSH terms: Solubility
  3. Sheshala R, Khan N, Darwis Y
    Chem Pharm Bull (Tokyo), 2011;59(8):920-8.
    PMID: 21804234
    The aims of the present research were to mask the intensely bitter taste of sumatriptan succinate and to formulate orally disintegrating tablets (ODTs) of the taste masked drug. Taste masking was performed by coating sumatriptan succinate with Eudragit EPO using spray drying technique. The resultant microspheres were evaluated for thermal analysis, yield, particle size, entrapment efficiency and in vitro taste masking. The tablets were formulated by mixing the taste masked microspheres with different types and concentrations of superdisintegrants and compressed using direct compression method followed by sublimation technique. The prepared tablets were evaluated for weight variation, thickness, hardness, friability, drug content, water content, in vitro disintegration time and in vitro drug release. All the tablet formulations disintegrated in vitro within 37-410 s. The optimized formulation containing 5% Kollidon CL-SF released more than 90% of the drug within 15 min and the release was comparable to that of commercial product (Suminat®). In human volunteers, the optimized formulation was found to have a pleasant taste and mouth feel and disintegrated in the oral cavity within 41 s. The optimized formulation was found to be stable and bioequivalent with Suminat®.
    Matched MeSH terms: Solubility
  4. Sheshala R, Khan N, Chitneni M, Darwis Y
    Arch Pharm Res, 2011 Nov;34(11):1945-56.
    PMID: 22139694 DOI: 10.1007/s12272-011-1115-y
    The aim of this study was to formulate cost effective taste-masked orally disintegrating tablets of ondansetron, a bitter drug using different superdisintegrants by a wet granulation technique. Microcrystalline cellulose (Avicel) as a diluent and disintegrant in addition to aspartame as a sweetener were used in all formulations. The prepared tablets were evaluated for weight variation, thickness, hardness, friability, drug content, water content, in vitro disintegration time and in vitro drug release. The tablets' hardness was maintained in the range of 2-3 kg and friability was <1% for all batches. All tablet formulations disintegrated rapidly in vitro within 5.83 to 33.0 sec. The optimized formulation containing 15% Polyplasdone XL-10 released more than 90% of drug within 5 min and the release was comparable to that of a commercial product. In human volunteers, optimized formulation was found to have a pleasant taste and mouth feel and they disintegrated in the oral cavity within 12 sec. The stability results were also satisfactory. A pharmacokinetic study with the optimized formulation was performed in comparison with a reference (Zofer MD 8®) and they were found to be bioequivalent. In conclusion, a cost effective ondansetron orally disintegrating tablet was successfully prepared with acceptable hardness, desirable taste and rapid disintegration in the oral cavity.
    Matched MeSH terms: Solubility
  5. Sheshala R, Peh KK, Darwis Y
    Drug Dev Ind Pharm, 2009 Nov;35(11):1364-74.
    PMID: 19832637 DOI: 10.3109/03639040902939213
    AIM: The aim of this study was to prepare insulin-loaded poly(lactic acid)-polyethylene glycol microspheres that could control insulin release at least for 1 week and evaluate their in vivo performance in a streptozotocin-induced diabetic rat model.
    METHODS: The microspheres were prepared using a water-in-oil-in-water double emulsion solvent evaporation technique. Different formulation variables influencing the yield, particle size, entrapment efficiency, and in vitro release profiles were investigated. The pharmacokinetic study of optimized formulation was performed with single dose in comparison with multiple dose of Humulin 30/70 as a reference product in streptozotocin-induced diabetic rats.
    RESULTS: The optimized formulation of insulin microspheres was nonporous, smooth-surfaced, and spherical in structure under scanning electron microscope with a mean particle size of 3.07 microm and entrapment efficiency of 42.74% of the theoretical amount incorporated. The in vitro insulin release profiles was characterized by a bimodal behavior with an initial burst release because of the insulin adsorbed on the microsphere surface, followed by slower and continuous release corresponding to the insulin entrapped in polymer matrix.
    CONCLUSIONS: The optimized formulation and reference were comparable in the extent of absorption. Consequently, these microspheres can be proposed as new controlled parenteral delivery system.
    Matched MeSH terms: Solubility
  6. Sheikhy Narany T, Aris AZ, Sefie A, Keesstra S
    Sci Total Environ, 2017 Dec 01;599-600:844-853.
    PMID: 28501010 DOI: 10.1016/j.scitotenv.2017.04.171
    The conversions of forests and grass land to urban and farmland has exerted significant changes on terrestrial ecosystems. However, quantifying how these changes can affect the quality of water resources is still a challenge for hydrologists. Nitrate concentrations can be applied as an indicator to trace the link between land use changes and groundwater quality due to their solubility and easy transport from their source to the groundwater. In this study, 25year records (from 1989 to 2014) of nitrate concentrations are applied to show the impact of land use changes on the quality of groundwater in Northern Kelantan, Malaysia, where large scale deforestation in recent decades has occurred. The results from the integration of time series analysis and geospatial modelling revealed that nitrate (NO3-N) concentrations significantly increased with approximately 8.1% and 3.89% annually in agricultural and residential wells, respectively, over 25years. In 1989 only 1% of the total area had a nitrate value greater than 10mg/L; and this value increased sharply to 48% by 2014. The significant increase in nitrate was only observed in a shallow aquifer with a 3.74% annual nitrate increase. Based on the result of the Autoregressive Integrated Moving Average (ARIMA) model the nitrate contamination is expected to continue to rise by about 2.64% and 3.9% annually until 2030 in agricultural and residential areas. The present study develops techniques for detecting and predicting the impact of land use changes on environmental parameters as an essential step in land and water resource management strategy development.
    Matched MeSH terms: Solubility
  7. Shehab ZN, Jamil NR, Aris AZ
    Sci Rep, 2020 11 23;10(1):20360.
    PMID: 33230250 DOI: 10.1038/s41598-020-77454-8
    Phase distribution of emerging organic contaminants is highly influential in their presence, fate and transport in surface water. Therefore, it is crucial to determine their state, partitioning behaviour and tendencies in water environments. In this study, Bisphenol A was investigated in both colloidal and soluble phases in water. BPA concentrations ranged between 1.13 and 5.52 ng L-1 in the soluble phase and n.d-2.06 ng L-1 in the colloidal phase, respectively. BPA was dominant in the soluble phase, however, the colloidal contribution ranged between 0 and 24% which implied that colloids can play a significant role in controlling BPA's transportation in water. Urban and industrial areas were the main sources of BPA while forest areas displayed lower levels outside the populated domains. pH levels were between 6.3 and 7.4 which might have affected BPA's solubility in water to some extent. The particle size distribution showed that the majority of the particles in river samples were smaller than 1.8 µm in diameter with a small presence of nanoparticles. Zeta potential varied between - 25 and - 18 mV, and these negative values suggested instability of particles. Furthermore, BPA was positively correlated with BOD, COD and NH3-N which might indicate that these organic compounds were released concurrently with BPA. RQ assessment showed low levels of risk towards algae and fish in the study area.
    Matched MeSH terms: Solubility
  8. Shariffa, Y.N., Uthumporn, U., Karim, A.A., Zaibunnisa, A.H
    MyJurnal
    This study investigated the effect of annealing treatment (at 50°C for 72 h) on hydrolysis of tapioca and sweet potato starches using a raw starch hydrolyzing enzyme namely STARGEN 001 (a blend from fungal α-amylase and glucoamylase) at sub-gelatinization temperature (35°C) for 24 h. The degree of hydrolysis of the starches was evaluated based on the dextrose equivalent (DE) value. The hydrolyzed starches were then characterized in terms of its morphology, swelling power and solubility, gelatinization and pasting properties, amylose content and x-ray diffraction pattern. After 24 h of hydrolysis, annealed starches were hydrolyzed to a greater degree with higher DE value compared to native starches (40% vs 33% for tapioca; and 29% vs 24% for sweet potato starch). Scanning electron microscopy (SEM) micrographs revealed a more porous granules and rougher surface in annealed starches than their native counterparts. The swelling power and solubility of annealed starches decreased significantly. Annealing was found to affect the pasting properties of the starches appreciably and increase the starch gelatinization temperature. The amylose content in hydrolyzed annealed tapioca and sweet potato starches increased while no significant changes observed in the X-ray diffraction of those starches. This study shows that the annealing treatment can be used as a way to increase the degree of hydrolysis of tapioca and sweet potato starches at sub-gelatinization temperature using a raw starch hydrolyzing enzyme.
    Matched MeSH terms: Solubility
  9. Shariffa YN, Tan TB, Uthumporn U, Abas F, Mirhosseini H, Nehdi IA, et al.
    Food Res Int, 2017 11;101:165-172.
    PMID: 28941679 DOI: 10.1016/j.foodres.2017.09.005
    The aim of this study was to develop formulations to produce lycopene nanodispersions and to investigate the effects of the homogenization pressure on the physicochemical properties of the lycopene nanodispersion. The samples were prepared by using emulsification-evaporation technique. The best formulation was achieved by dispersing an organic phase (0.3% w/v lycopene dissolved in dichloromethane) in an aqueous phase (0.3% w/v Tween 20 dissolved in deionized water) at a ratio of 1:9 by using homogenization process. The increased level of homogenization pressure to 500bar reduced the particle size and lycopene concentration significantly (p<0.05). Excessive homogenization pressure (700-900bar) resulted in large particle sizes with high dispersibility. The zeta potential and turbidity of the lycopene nanodispersion were significantly influenced by the homogenization pressure. The results from this study provided useful information for producing small-sized lycopene nanodispersions with a narrow PDI and good stability for application in beverage products.
    Matched MeSH terms: Solubility
  10. Shantini K, Yahya AR, Amirul AA
    Appl Biochem Biotechnol, 2015 Jul;176(5):1315-34.
    PMID: 25951779 DOI: 10.1007/s12010-015-1648-5
    Copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] has been the center of attention in the bio-industrial fields, as it possesses superior mechanical properties compared to poly(3-hydroxybutyrate) [P(3HB)]. The usage of oleic acid and 1-pentanol was exploited as the carbon source for the production of P(3HB-co-3HV) copolymer by using a locally isolated strain Cupriavidus sp. USMAA2-4. In this study, the productivity of polyhydroxyalkanoate (PHA) was improved by varying the frequency of feeding in fed-batch culture. The highest productivity (0.48 g/L/h) that represents 200 % increment was obtained by feeding the carbon source and nitrogen source three times and also by considering the oxygen uptake rate (OUR) and oxygen transfer rate (OTR). A significantly higher P(3HB-co-3HV) concentration of 25.7 g/L and PHA content of 66 wt% were obtained. The 3-hydroxyvalerate (3HV) monomer composition obtained was 24 mol% with the growth of 13.3 g/L. The different frequency of feeding carried out has produced a blend copolymer and has broadened the monomer distribution. In addition, increase in number of granules was also observed as the frequency of feeding increases. In general, the most glaring increment in productivity offer advantage for industrial P(3HB-co-3HV) production, and it is crucial in developing cost-effective processes for commercialization.
    Matched MeSH terms: Solubility
  11. Shamsi S, Chen Y, Lim LY
    Int J Pharm, 2015 Nov 10;495(1):194-203.
    PMID: 26319630 DOI: 10.1016/j.ijpharm.2015.08.066
    Curcumin (CUR) has been formulated into a host of nano-sized formulations in a bid to improve its in vivo solubility, stability and bioavailability. The aim of this study was to investigate whether the encapsulation of CUR in nanocarriers would impede its biological interactivity, specifically its potential anti-cancer adjuvant activity via the modulation of CYP enzymes in vitro. NanoCUR, a micellar dispersion prepared via a thin film method using only Pluronic F127 as excipient, was amenable to lyophilization, and retained its nano-sized spherical dimensions (17-33 nm) upon reconstitution with water followed by dilution to 5 μM with HBSS or EMEM. NanoCUR was a weaker cytotoxic agent compared to CUR in solution (sCUR), affecting HepG2 cell viability only when the incubation time was prolonged from 4h to 48 h. Correlation with 2h uptake data suggests this was due to a lower cellular uptake rate of CUR from NanoCUR than from sCUR. The poorer CUR accessibility might also account for NanoCUR being a weaker inhibitor of CYP2C9 and CYP2D6 than sCUR. NanoCUR was, however, 1.76-fold more potent against the CYP3A4 (IC50 5.13 ± 0.91 μM) metabolic function. The higher activity against CYP3A4 might be attributed to the synergistic action of Pluronic F127, since the blank micellar dispersion also inhibited CYP3A4 activity. Both sCUR and NanoCUR had no effect on the CYP3A4 mRNA levels in the HepG2 cells. NanoCUR therefore, maintained most of the biological activities of CUR in vitro, albeit at a lower potency and response rate.
    Matched MeSH terms: Solubility
  12. Shah SM, Ullah F, Khan S, Shah SM, de Matas M, Hussain Z, et al.
    Drug Des Devel Ther, 2016;10:3837-3850.
    PMID: 27920499
    Artemether (ARTM) is a very effective antimalarial drug with poor solubility and consequently low bioavailability. Smart nanocrystals of ARTM with particle size of 161±1.5 nm and polydispersity index of 0.172±0.01 were produced in <1 hour using a wet milling technology, Dena(®) DM-100. The crystallinity of the processed ARTM was confirmed using differential scanning calorimetry and powder X-ray diffraction. The saturation solubility of the ARTM nanocrystals was substantially increased to 900 µg/mL compared to the raw ARTM in water (145.0±2.3 µg/mL) and stabilizer solution (300.0±2.0 µg/mL). The physical stability studies conducted for 90 days demonstrated that nanocrystals stored at 2°C-8°C and 25°C were very stable compared to the samples stored at 40°C. The nanocrystals were also shown to be stable when processed at acidic pH (2.0). The solubility and dissolution rate of ARTM nanocrystals were significantly increased (P<0.05) compared to those of its bulk powder form. The results of in vitro studies showed significant antimalarial effect (P<0.05) against Plasmodium falciparum and Plasmodium vivax. The IC50 (median lethal oral dose) value of ARTM nanocrystals was 28- and 54-fold lower than the IC50 value of unprocessed drug and 13- and 21-fold lower than the IC50 value of the marketed tablets, respectively. In addition, ARTM nanocrystals at the same dose (2 mg/kg) showed significantly (P<0.05) higher reduction in percent parasitemia (89%) against P. vivax compared to the unprocessed (27%), marketed tablets (45%), and microsuspension (60%). The acute toxicity study demonstrated that the LD50 value of ARTM nanocrystals is between 1,500 mg/kg and 2,000 mg/kg when given orally. This study demonstrated that the wet milling technology (Dena(®) DM-100) can produce smart nanocrystals of ARTM with enhanced antimalarial activities.
    Matched MeSH terms: Solubility
  13. Shafie MH, Yusof R, Samsudin D, Gan CY
    Int J Biol Macromol, 2020 Nov 15;163:1276-1282.
    PMID: 32673725 DOI: 10.1016/j.ijbiomac.2020.07.109
    The potential of Averrhoa bilimbi pectin (ABP) as a source of biopolymer for edible film (EF) production was explored, and deep eutectic solvent (DES) (1% w/w) containing choline chloride-citric acid monohydrate at a molar ratio of 1:1 was used as the plasticizer. The EF-ABP3:1, which was produced from ABP with large branch size, showed a higher value of melting temperature (175.30 °C), tensile stress (7.32 MPa) and modulus (33.64 MPa). The EF-ABP3:1 also showed better barrier properties by obtaining the lowest water vapor transmission rates (1.10-1.18 mg/m2.s) and moisture absorption values (2.61-32.13%) depending on the relative humidity compared to other EF-ABPs (1.39-1.83 mg/m2.s and 3.48-51.50%, respectively) that have linear structure with smaller branch size. From these results, it was suggested that the galacturonic acid content, molecular weight, degree of esterification and pectin structure of ABP significantly influenced the properties of EFs. The interaction of highly branched pectin chains was stronger than the linear chains, thus reduced the effect of plasticizer and produced a mechanically stronger EF with better barrier properties. Hence, it was suggested that these EFs could be used as alternative degradable packaging/coating materials.
    Matched MeSH terms: Solubility/drug effects
  14. Shafie MH, Yusof R, Gan CY
    Carbohydr Polym, 2019 Jul 15;216:303-311.
    PMID: 31047070 DOI: 10.1016/j.carbpol.2019.04.007
    The Box-Behnken design was applied to optimize the extraction of pectin from Averrhoa bilimbi (ABP) using deep eutectic solvents (DES). The four variables of extraction were percentage of DES (X1), extraction time (X2), temperature (X3), and molar ratio of DES components (X4). The quadratic regression equation was established as a predicted model with R2 value of 0.9375. The optimal condition was X1 = 3.74% (w/v), X2 = 2.5 h, X3 = 80 °C, and X4 = 1:1. No significant difference between the predicted (14.70%) and experimental (14.44%) maximum yield of sample was noted. Characterization of physico-chemical properties characterization of ABP was performed. The main components of ABP were galacturonic acids, arabinoses, and xyloses. ABP also showed good functional properties such as water holding capacity (3.70 g/g), oil holding capacity (2.40 g/g), and foaming capacity (133.33%). The results also showed that ABP exhibited free radical scavenging activity (41.46%) and ferric reducing antioxidant power (1.15 mM).
    Matched MeSH terms: Solubility
  15. Shafie MH, Gan CY
    Int J Biol Macromol, 2020 Apr 15;149:835-843.
    PMID: 32027904 DOI: 10.1016/j.ijbiomac.2020.02.013
    The deep eutectic solvents (DESs), which were made from different molar ratios (3:1, 2:1, 1:1, 1:2, 1:3) of choline chloride and citric acid monohydrate, were used as media for the pectic polysaccharide extraction from Averrhoa bilmbi (ABP). The physico-chemical, structural, functional and antioxidant properties of ABP were subsequently determined. The ABP was found to be xylogalacturonan. Moreover, results showed that different structures (i.e. linearity of pectin and branch size) of ABP were obtained, hence, affecting the solubility and functional properties due to the surface availability and steric effect. In addition, when increasing the molar ratio of citric acid monohydrate in DES, lower pH and higher TPC values were observed. These values were correlated with antioxidant activities (i.e. free radical scavenging activity and ferric reducing antioxidant power) of ABP. In conclusion, the molar ratio of the DES components plays an important role in extracting ABP with the aforementioned properties.
    Matched MeSH terms: Solubility
  16. Shafaei A, Esmailli K, Farsi E, Aisha AF, Abul Majid AM, Ismail Z
    PMID: 26467526 DOI: 10.1186/s12906-015-0885-z
    Orthosiphon stamineus (OS) Benth is a medicinal plant and native in Southeast Asia. Pharmacological effects of OS are attributed to the presence of lipophilic flavones. However; lipophilic compounds suffer from poor aqueous solubility which limits the OS oral bioavailability and therapeutic applications. Therefore, OS was prepared in nano formulation form using liposomes from soybean phospholipids. The aim of the present study is to evaluate the in vitro genotoxicity and in vivo oral toxicity of nano liposomes of OS ethanolic extract (OS-EL).
    Matched MeSH terms: Solubility
  17. Shaedi N, Naharudin I, Choo CY, Wong TW
    Carbohydr Polym, 2021 Feb 15;254:117312.
    PMID: 33357875 DOI: 10.1016/j.carbpol.2020.117312
    Vitexin of Ficus deltoidea exhibits intestinal α-glucosidase inhibitory and blood glucose lowering effects. This study designs oral intestinal-specific alginate nanoparticulate system of vitexin. Nanospray-dried alginate, alginate/stearic acid and alginate-C18 conjugate nanoparticles were prepared. Stearic acid was adopted to hydrophobize the matrix and minimize premature vitexin release in stomach, whereas C-18 conjugate as immobilized fatty acid to sustain hydrophobic effect and drug release. Nanoparticles were compacted with polyethylene glycol (PEG 3000, 10,000 and 20,000). The physicochemical, drug release, in vivo blood glucose lowering and intestinal vitexin content of nanoparticles and compact were determined. Hydrophobization of alginate nanoparticles promoted premature vitexin release. Compaction of nanoparticles with PEG minimized vitexin release in the stomach, with stearic acid loaded nanoparticles exhibiting a higher vitexin release in the intestine. The introduction of stearic acid reduced vitexin-alginate interaction, conferred alginate-stearic acid mismatch, and dispersive stearic acid-induced particle breakdown with intestinal vitexin release. Use of PEG 10,000 in compaction brought about PEG-nanoparticles interaction that negated initial vitexin release. The PEG dissolution in intestinal phase subsequently enabled particle breakdown and vitexin release. The PEG compacted nanoparticles exhibited oral intestinal-specific vitexin release, with positive blood glucose lowering and enhanced intestinal vitexin content in vivo.
    Matched MeSH terms: Solubility
  18. Shaaruddin S, Mahmood Z, Ismail H, Mohd Ghazali H, Hamzah MY, Muhammad K
    J Food Sci Technol, 2019 Jul;56(7):3461-3470.
    PMID: 31274914 DOI: 10.1007/s13197-019-03832-4
    Encapsulation has been used to overcome the problem of instability of functional pigments such as carotenoids from natural sources. In this study, β-carotene in carrot juice was spray dried with four different wall materials namely maltodextrin, resistant maltodextrin, octenyl succinate anhydride (OSA) starches Capsul (CAP) and HICAP-100 (HCAP). The objective of this research was to study the effects of various wall materials on physicochemical properties and stability of β-carotene powders along with its stability after incorporation into sugar confection. All four wall materials produced powders of acceptable quality in terms of moisture content, water activity, hygroscopicity, solubility as well as onset glass transition temperature. OSA starches exhibited better pigment retention post spray drying where juices encapsulated with HCAP showed the highest retention (94.34%). This was also represented in more orange Hue values (H°) in powders produced with CAP (53.93) and HCAP (53.33). Powders produced with HCAP also showed the longest half-life after storage at 4 °C, 25 °C, and 40 °C, as well as under exposure to light. Similarly, carrot powders produced with OSA starches also exhibited better β-carotene retention after production of hard candy confection. Though candies with HCAP encapsulated juices showed the highest β-carotene retention post candy processing, candies with CAP encapsulated carrot juices exhibited better long term stability after storage at 25 °C and 40 °C as well as under exposure to light.
    Matched MeSH terms: Solubility
  19. Seyyedi M, Mahmud HKB, Verrall M, Giwelli A, Esteban L, Ghasemiziarani M, et al.
    Sci Rep, 2020 Feb 27;10(1):3624.
    PMID: 32107400 DOI: 10.1038/s41598-020-60247-4
    Observations and modeling studies have shown that during CO2 injection into underground carbonate reservoirs, the dissolution of CO2 into formation water forms acidic brine, leading to fluid-rock interactions that can significantly impact the hydraulic properties of the host formation. However, the impacts of these interactions on the pore structure and macroscopic flow properties of host rock are poorly characterized both for the near-wellbore region and deeper into the reservoir. Little attention has been given to the influence of pressure drop from the near-wellbore region to reservoir body on disturbing the ionic equilibrium in the CO2-saturated brine and consequent mineral precipitation. In this paper, we present the results of a novel experimental procedure designed to address these issues in carbonate reservoirs. We injected CO2-saturated brine into a composite core made of two matching grainstone carbonate core plugs with a tight disk placed between them to create a pressure profile of around 250 psi resembling that prevailing in reservoirs during CO2 injection. We investigated the impacts of fluid-rock interactions at pore and continuum scale using medical X-ray CT, nuclear magnetic resonance, and scanning electron microscopy. We found that strong calcite dissolution occurs near to the injection point, which leads to an increase in primary intergranular porosity and permeability of the near injection region, and ultimately to wormhole  formation. The strong heterogeneous dissolution of calcite grains leads to the formation of intra-granular micro-pores. At later stages of the dissolution, the internal regions of ooids become accessible to the carbonated brine, leading to the formation of moldic porosity. At distances far from the injection point, we observed minimal or no change in pore structure, pore roughness, pore populations, and rock hydraulic properties. The pressure drop of 250 psi slightly disturbed the chemical equilibrium of the system, which led to minor precipitation of sub-micron sized calcite crystals but due to the large pore throats of the rock, these deposits had no measurable impact on rock permeability. The trial illustrates that the new procedure is valuable for investigating fluid-rock interactions by reproducing the geochemical consequences of relatively steep pore pressure gradients during CO2 injection.
    Matched MeSH terms: Solubility
  20. Senjoti FG, Mahmood S, Jaffri JM, Mandal UK
    Iran J Pharm Res, 2016;15(1):53-70.
    PMID: 27610147
    An oral sustained-release floating tablet formulation of metformin HCl was designed and developed. Effervescence and swelling properties were attributed on the developed tablets by sodium bicarbonate and HPMC-PEO polymer combination, respectively. Tablet composition was optimized by response surface methodology (RSM). Seventeen (17) trial formulations were analyzed according to Box-Behnken design of experiment where polymer content of HPMC and PEO at 1: 4 ratio (A), amount of sodium bi-carbonate (B), and amount of SSG (C) were adopted as independent variables. Floating lag time in sec (Y1), cumulative percent drug released at 1 h (Y2) and 12 h (Y3) were chosen as response variables. Tablets from the optimized formulation were also stored at accelerated stability condition (40°C and 75% RH) for 3 months to assess their stability profile. RSM could efficiently optimize the tablet composition with excellent prediction ability. In-vitro drug release until 12 h, floating lag time, and duration of floating were dependent on the amount of three selected independent variables. Optimized tablets remained floating for more than 24 h with a floating lag time of less than 4 min. Based on best fitting method, optimized formulation was found to follow Korsmeyer-Peppas release kinetic. Accelerated stability study revealed that optimized formulation was stable for three months without any major changes in assay, dissolution profile, floating lag time and other physical properties.
    Matched MeSH terms: Solubility
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