Displaying publications 1 - 20 of 429 in total

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  1. Chilakamarry CR, Mahmood S, Saffe SNBM, Arifin MAB, Gupta A, Sikkandar MY, et al.
    3 Biotech, 2021 May;11(5):220.
    PMID: 33968565 DOI: 10.1007/s13205-021-02734-7
    Over recent years, keratin has gained great popularity due to its exceptional biocompatible and biodegradable nature. It has shown promising results in various industries like poultry, textile, agriculture, cosmetics, and pharmaceutical. Keratin is a multipurpose biopolymer that has been used in the production of fibrous composites, and with necessary modifications, it can be developed into gels, films, nanoparticles, and microparticles. Its stability against enzymatic degradation and unique biocompatibility has found their way into biomedical applications and regenerative medicine. This review discusses the structure of keratin, its classification and its properties. It also covers various methods by which keratin is extracted like chemical hydrolysis, enzymatic and microbial treatment, dissolution in ionic liquids, microwave irradiation, steam explosion technique, and thermal hydrolysis or superheated process. Special emphasis is placed on its utilisation in the form of hydrogels, films, fibres, sponges, and scaffolds in various biotechnological and industrial sectors. The present review can be noteworthy for the researchers working on natural protein and related usage.
    Matched MeSH terms: Solubility
  2. Bello B, Mustafa S, Tan JS, Ibrahim TAT, Tam YJ, Ariff AB, et al.
    3 Biotech, 2018 Aug;8(8):346.
    PMID: 30073131 DOI: 10.1007/s13205-018-1362-4
    This paper deliberates the extraction, characterization and examination of potential application of soluble polysaccharides of palm kernel cake (PKC) as a prebiotic. The PKC was defatted and crude polysaccharide was obtained through water, citric acid or NaOH extraction. The physiochemical properties of the extracted polysaccharides viz. total carbohydrates, protein content, solubility rate, monosaccharides composition, structural information and thermal properties were also determined. The extracted soluble polysaccharides were further subjected to a digestibility test using artificial human gastric juice. Finally, their prebiotic potential on two probiotics, namely Lactobacillus plantarum ATCC 8014 and Lb. rhamnosus ATCC 53103 were evaluated in vitro. It was observed that PKC contained ash (5.2%), moisture (7.4%), carbohydrates (65.8%), protein (16.5%) and fat (5.1%). There were significant differences (P  95%). Protein content in SCPW, SCPCA and SCPN are 0.72, 0.40 and 0.58, respectively, and the peaks which indicated the presence of protein were observed at approximately 1640 cm-1 (amide I). FTIR spectroscopy revealed that the polysaccharides extracts were linked to β and α-glycosidic bonds and thermal analysis using differential scanning calorimeter (DSC) showed the main degradation temperature of SP is about 121 to 125 °C. The SP were found to be highly resistance (> 96%) to hydrolysis when subjected to artificial human gastric juice. The prebiotics potentials of the polysaccharides on probiotics in vitro demonstrated an increase in proliferation of Lb. plantarum ATCC 8014 and Lb. rhamnosus ATCC 53103 with decrease in the pH of the medium and producing organic acids.All the above findings strongly indicated that polysaccharides extracted from PKC, an industrial waste, have a potential to be exploited as novel prebiotics.
    Matched MeSH terms: Solubility
  3. Aziz HA, Tan YT, Peh KK
    AAPS PharmSciTech, 2012 Mar;13(1):35-45.
    PMID: 22101965 DOI: 10.1208/s12249-011-9707-x
    Microencapsulation of water-soluble drugs using coacervation-phase separation method is very challenging, as these drugs partitioned into the aqueous polymeric solution, resulting in poor drug entrapment. For evaluating the effect of ovalbumin on the microencapsulation of drugs with different solubility, pseudoephedrine HCl, verapamil HCl, propranolol HCl, paracetamol, and curcuminoid were used. In addition, drug mixtures comprising of paracetamol and pseudoephedrine HCl were also studied. The morphology, encapsulation efficiency, particle size, and in vitro release profile were investigated. The results showed that the solubility of the drug determined the ratio of ovalbumin to be used for successful microencapsulation. The optimum ratios of drug, ovalbumin, and gelatin for water-soluble (pseudoephedrine HCl, verapamil HCl, and propranolol HCl), sparingly water-soluble (paracetamol), and water-insoluble (curcuminoid) drugs were found to be 1:1:2, 2:3:5, and 1:3:4. As for the drug mixture, the optimum ratio of drug, ovalbumin, and gelatin was 2:3:5. Encapsulated particles prepared at the optimum ratios showed high yield, drug loading, entrapment efficiency, and sustained release profiles. The solubility of drug affected the particle size of the encapsulated particle. Highly soluble drugs resulted in smaller particle size. In conclusion, addition of ovalbumin circumvented the partitioning effect, leading to the successful microencapsulation of water-soluble drugs.
    Matched MeSH terms: Solubility
  4. Liew KB, Tan YT, Peh KK
    AAPS PharmSciTech, 2012 Mar;13(1):134-42.
    PMID: 22167416 DOI: 10.1208/s12249-011-9729-4
    The aim of this study was to develop a taste-masked oral disintegrating film (ODF) containing donepezil, with fast disintegration time and suitable mechanical strength, for the treatment of Alzheimer's disease. Hydroxypropyl methylcellulose, corn starch, polyethylene glycol, lactose monohydrate and crosspovidone served as the hydrophilic polymeric bases of the ODF. The uniformity, in vitro disintegration time, drug release and the folding endurance of the ODF were examined. The in vitro results showed that 80% of donepezil hydrochloride was released within 5 minutes with mean disintegration time of 44 seconds. The result of the film flexibility test showed that the number of folding time to crack the film was 40 times, an indication of sufficient mechanical property for patient use. A single-dose, fasting, four-period, eight-treatment, double-blind study involving 16 healthy adult volunteers was performed to evaluate the in situ disintegration time and palatability of ODF. Five parameters, namely taste, aftertaste, mouthfeel, ease of handling and acceptance were evaluated. The mean in situ disintegration time of ODF was 49 seconds. ODF containing 7 mg of sucralose were more superior than saccharin and aspartame in terms of taste, aftertaste, mouthfeel and acceptance. Furthermore, the ODF was stable for at least 6 months when stored at 40°C and 75% relative humidity.
    Matched MeSH terms: Solubility/drug effects
  5. Tamilvanan S, Kumar BA, Senthilkumar SR, Baskar R, Sekharan TR
    AAPS PharmSciTech, 2010 Jun;11(2):904-9.
    PMID: 20496017 DOI: 10.1208/s12249-010-9455-3
    The objectives of the present work were to prepare castor oil-based nano-sized emulsion containing cationic droplets stabilized by poloxamer-chitosan emulgator film and to assess the kinetic stability of the prepared cationic emulsion after subjecting it to thermal processing and freeze-thaw cycling. Presence of cryoprotectants (5%, w/w, sucrose +5%, w/w, sorbitol) improved the stability of emulsions to droplet aggregation during freeze-thaw cycling. After storing the emulsion at 4 degrees C, 25 degrees C, and 37 degrees C over a period of up to 6 months, no significant change was noted in mean diameter of the dispersed oil droplets. However, the emulsion stored at the highest temperature did show a progressive decrease in the pH and zeta potential values, whereas the emulsion kept at the lowest temperatures did not. This indicates that at 37 degrees C, free fatty acids were formed from the castor oil, and consequently, the liberated free fatty acids were responsible for the reduction in the emulsion pH and zeta potential values. Thus, the injectable castor oil-based nano-sized emulsion could be useful for incorporating various active pharmaceutical ingredients that are in size from small molecular drugs to large macromolecules such as oligonucleotides.
    Matched MeSH terms: Solubility
  6. Zeeshan F, Bukhari NI
    AAPS PharmSciTech, 2010 Jun;11(2):910-6.
    PMID: 20496016 DOI: 10.1208/s12249-010-9456-2
    Modified-release multiple-unit tablets of loratadine and pseudoephedrine hydrochloride with different release profiles were prepared from the immediate-release pellets comprising the above two drugs and prolonged-release pellets containing only pseudoephedrine hydrochloride. The immediate-release pellets containing pseudoephedrine hydrochloride alone or in combination with loratadine were prepared using extrusion-spheronization method. The pellets of pseudoephedrine hydrochloride were coated to prolong the drug release up to 12 h. Both immediate- and prolonged-release pellets were filled into hard gelatin capsule and also compressed into tablets using inert tabletting granules of microcrystalline cellulose Ceolus KG-801. The in vitro drug dissolution study conducted using high-performance liquid chromatography method showed that both multiple-unit capsules and multiple-unit tablets released loratadine completely within a time period of 2 h, whereas the immediate-release portion of pseudoephedrine hydrochloride was liberated completely within the first 10 min of dissolution study. On the other hand, the release of pseudoephedrine hydrochloride from the prolonged release coated pellets was prolonged up to 12 hr and followed zero-order release kinetic. The drug dissolution profiles of multiple-unit tablets and multiple-unit capsules were found to be closely similar, indicating that the integrity of pellets remained unaffected during the compression process. Moreover, the friability, hardness, and disintegration time of multiple-unit tablets were found to be within BP specifications. In conclusion, modified-release pellet-based tablet system for the delivery of loratadine and pseudoephedrine hydrochloride was successfully developed and evaluated.
    Matched MeSH terms: Solubility
  7. Zeeshan F, Peh KK, Tan YT
    AAPS PharmSciTech, 2009;10(3):850-7.
    PMID: 19554454 DOI: 10.1208/s12249-009-9278-2
    Compaction of controlled-release coated pellets into tablets is challenging because of the fusion of pellets and the rupturing of coated film. The difficulty in compaction intensifies with the use of extremely water-soluble drugs. Therefore, the present study was conducted to prepare and compact pellets containing pseudoephedrine hydrochloride as an extremely water-soluble model drug. The pellets were produced using an extrusion-spheronization technique. The drug-loaded pellets were coated to extend the drug release up to 12-h employing various polymers, and then they were compressed into tablets using microcrystalline cellulose Ceolus KG-801 as a novel tabletting excipient. The in vitro drug release studies of coated pellets and tablets were undertaken using the USP basket method in dissolution test apparatus I. The amount of drug released was analyzed at a wavelength of 215 nm. The combined coatings of hydroxypropyl methylcellulose and Kollicoat SR-30D yielded 12-h extended-release pellets with drug release independent of pH of dissolution medium following zero-order kinetics. The drug release from the tablets prepared using inert Celous KG-801 granules as tabletting excipient was found faster than that of coated pellets. However, a modification in drug release rate occurred with the incorporation of inert Ceolus KG-801 pellets. The drug dissolution profile from tablets containing 40% w/w each of coated pellets and inert granules along with 20% w/w inert pellets was found to be closely similar to that of coated pellets. Furthermore, the friability, tensile strength, and disintegration time of the tablets were within the USP specifications.
    Matched MeSH terms: Solubility
  8. Tan YT, Peh KK, Al-Hanbali O
    AAPS PharmSciTech, 2000;1(3):E24.
    PMID: 14727910
    This study examined the mechanical (hardness, compressibility, adhesiveness, and cohesiveness) and rheological (zero-rate viscosity and thixotropy) properties of polyethylene glycol (PEG) gels that contain different ratios of Carbopol 934P (CP) and polyvinylpyrrolidone K90 (PVP). Mechanical properties were examined using a texture analyzer (TA-XT2), and rheological properties were examined using a rheometer (Rheomat 115A). In addition, lidocaine release from gels was evaluated using a release apparatus simulating the buccal condition. The results indicated that an increase in CP concentration significantly increased gel compressibility, hardness, and adhesiveness, factors that affect ease of gel removal from container, ease of gel application onto mucosal membrane, and gel bioadhesion. However, CP concentration was negatively correlated with gel cohesiveness, a factor representing structural reformation. In contrast, PVP concentration was negatively correlated with gel hardness and compressibility, but positively correlated with gel cohesiveness. All PEG gels exhibited pseudoplastic flow with thixotropy, indicating a general loss of consistency with increased shearing stress. Drug release T50% was affected by the flow rate of the simulated saliva solution. A reduction in the flow rate caused a slower drug release and hence a higher T50% value. In addition, drug release was significantly reduced as the concentrations of CP and PVP increased because of the increase in zero-rate viscosity of the gels. Response surfaces and contour plots of the dependent variables further substantiated that various combinations of CP and PVP in the PEG gels offered a wide range of mechanical, rheological, and drug-release characteristics. A combination of CP and PVP with complementary physical properties resulted in a prolonged buccal drug delivery.
    Matched MeSH terms: Solubility
  9. Billa N, Yuen KH
    AAPS PharmSciTech, 2000;1(4):E30.
    PMID: 14727895
    The purpose of this research was to study processing variables at the laboratory and pilot scales that can affect hydration rates of xanthan gum matrices containing diclofenac sodium and the rate of drug release. Tablets from the laboratory scale and pilot scale proceedings were made by wet granulation. Swelling indices of xanthan gum formulations prepared with different amounts of water were measured in water under a magnifying lens. Granules were thermally treated in an oven at 60 degrees C, 70 degrees C, and 80 degrees C to study the effects of elevated temperatures on drug release from xanthan gum matrices. Granules from the pilot scale formulations were bulkier compared to their laboratory scale counterparts, resulting in more porous, softer tablets. Drug release was linear from xanthan gum matrices prepared at the laboratory scale and pilot scales; however, release was faster from the pilot scales. Thermal treatment of the granules did not affect the swelling index and rate of drug release from tablets in both the pilot and laboratory scale proceedings. On the other hand, the release from both proceedings was affected by the amount of water used for granulation and the speed of the impeller during granulation. The data suggest that processing variables that affect the degree of wetness during granulation, such as increase in impeller speed and increase in amount of water used for granulation, also may affect the swelling index of xanthan gum matrices and therefore the rate of drug release.
    Matched MeSH terms: Solubility
  10. 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
  11. Chaudhary S, Nair AB, Shah J, Gorain B, Jacob S, Shah H, et al.
    AAPS PharmSciTech, 2021 Apr 09;22(3):127.
    PMID: 33835317 DOI: 10.1208/s12249-021-01995-y
    Being a candidate of BCS class II, dolutegravir (DTG), a recently approved antiretroviral drug, possesses solubility issues. The current research was aimed to improve the solubility of the DTG and thereby enhance its efficacy using the solid dispersion technique. In due course, the miscibility study of the drug was performed with different polymers, where Poloxamer 407 (P407) was found suitable to move forward. The solid dispersion of DTG and P407 was formulated using solvent evaporation technique with a 1:1 proportion of drug and polymer, where the solid-state characterization was performed using differential scanning calorimetry, Fourier transform infrared spectroscopy and X-ray diffraction. No physicochemical interaction was found between the DTG and P407 in the fabricated solid dispersion; however, crystalline state of the drug was changed to amorphous as evident from the X-ray diffractogram. A rapid release of DTG was observed from the solid dispersion (>95%), which is highly significant (p<0.05) as compared to pure drug (11.40%), physical mixture (20.07%) and marketed preparation of DTG (35.30%). The drug release from the formulated solid dispersion followed Weibull model kinetics. Finally, the rapid drug release from the solid dispersion formulation revealed increased Cmax (14.56 μg/mL) when compared to the physical mixture (4.12 μg/mL) and pure drug (3.45 μg/mL). This was further reflected by improved bioavailability of DTG (AUC: 105.99±10.07 μg/h/mL) in the experimental Wistar rats when compared to the AUC of animals administered with physical mixture (54.45±6.58 μg/h/mL) and pure drug (49.27±6.16 μg/h/mL). Therefore, it could be concluded that the dissolution profile and simultaneously the bioavailability of DTG could be enhanced by means of the solid dispersion platform using the hydrophilic polymer, P407, which could be projected towards improved efficacy of the drug in HIV/AIDS.
    Matched MeSH terms: Solubility
  12. Long CM, Tang K, Chokshi H, Fotaki N
    AAPS PharmSciTech, 2019 Feb 13;20(3):113.
    PMID: 30761437 DOI: 10.1208/s12249-019-1317-z
    The aim of this study is to investigate the dissolution properties of poorly soluble drugs from their pure form and their amorphous formulation under physiological relevant conditions for oral administration based on surface dissolution ultraviolet (UV) imaging. Dissolution of two poorly soluble drugs (cefuroxime axetil and itraconazole) and their amorphous formulations (Zinnat® and Sporanox®) was studied with the Sirius Surface Dissolution Imager (SDI). Media simulating the fasted state conditions (compendial and biorelevant) with sequential media/flow rate change were used. The dissolution mechanism of cefuroxime axetil in simulated gastric fluid (SGF), fasted state simulated gastric fluid (FaSSGF) and simulated intestinal fluid (SIF) is predominantly swelling as opposed to the convective flow in fasted state simulated intestinal fluid (FaSSIF-V1), attributed to the effect of mixed micelles. For the itraconazole compact in biorelevant media, a clear upward diffusion of the dissolved itraconazole into the bulk buffer solution is observed. Dissolution of itraconazole from the Sporanox® compact is affected by the polyethylene glycol (PEG) gelling layer and hydroxypropyl methylcellulose (HPMC) matrix, and a steady diffusional dissolution pattern is revealed. A visual representation and a quantitative assessment of dissolution properties of poorly soluble compounds and their amorphous formulation can be obtained with the use of surface dissolution imaging under in vivo relevant conditions.
    Matched MeSH terms: Solubility
  13. Kashim MZ, Tsegab H, Rahmani O, Abu Bakar ZA, Aminpour SM
    ACS Omega, 2020 Nov 17;5(45):28942-28954.
    PMID: 33225124 DOI: 10.1021/acsomega.0c02358
    The research presented here investigates the reaction mechanism of wollastonite in situ mineral carbonation for carbon dioxide (CO2) sequestration. Because wollastonite contains high calcium (Ca) content, it was considered as a suitable feedstock in the mineral carbonation process. To evaluate the reaction mechanism of wollastonite for geological CO2 sequestration (GCS), a series of carbonation experiments were performed at a range of temperatures from 35 to 90 °C, pressures from 1500 to 4000 psi, and salinities from 0 to 90,000 mg/L NaCl. The kinetics batch modeling results were validated with carbonation experiments at the specific pressure and temperature of 1500 psi and 65 °C, respectively. The results showed that the dissolution of calcium increases with increment in pressure and salinity from 1500 to 4000 psi and 0 to 90000 mg/L NaCl, respectively. However, the calcium concentration decreases by 49%, as the reaction temperature increases from 35 to 90 °C. Besides, it is clear from the findings that the carbonation efficiency only shows a small difference (i.e., ±2%) for changing the pressure and salinity, whereas the carbonation efficiency was shown to be enhanced by 62% with increment in the reaction temperature. These findings can provide information about CO2 mineralization of calcium silicate at the GCS condition, which may enable us to predict the fate of the injected CO2, and its subsurface geochemical evolution during the CO2-fluid-rock interaction.
    Matched MeSH terms: Solubility
  14. Maki MAA, Kumar PV, Cheah SC, Siew Wei Y, Al-Nema M, Bayazeid O, et al.
    ACS Omega, 2019 May 31;4(5):8767-8777.
    PMID: 31459966 DOI: 10.1021/acsomega.9b00109
    Several studies have shown that the mammalian target of rapamycin (mTOR) inhibitor; everolimus (EV) improves patient survival in several types of cancer. However, the meaningful efficacy of EV as a single agent for the treatment of colorectal cancer (CRC) has failed to be proven in multiple clinical trials. Combination therapy is one of the options that could increase the efficacy and decrease the toxicity of the anticancer therapy. This study revealed that the β-cyclodextrin (β-CD):FGF7 complex has the potential to improve the antiproliferative effect of EV by preventing FGF receptor activation and by enhancing EV cellular uptake and intracellular retention. Molecular docking techniques were used to investigate the possible interaction between EV, β-CD, and FGF7. Molecular docking insights revealed that β-CD and EV are capable to form a stable inclusion complex with FGF at the molecular level. The aqueous solubility of the inclusion complex was increased (3.1 ± 0.23 μM) when compared to the aqueous solubility of pure EV (1.7 ± 0.16 μM). In addition, the in vitro cytotoxic activity of a FGF7:β-CD:EV complex on Caco-2 cell line was investigated using real-time xCELLigence technology. The FGF7:β-CD:EV complex has induced apoptosis of Caco-2 cells and shown higher cytotoxic activity than the parent drug EV. With the multitargets effect of β-CD:FGF7 and EV, the antiproliferative effect of EV was remarkably improved as the IC50 value of EV was reduced from 9.65 ± 1.42 to 1.87 ± 0.33 μM when compared to FGF7:β-CD:EV complex activity. In conclusion, the findings advance the understanding of the biological combinational effects of the β-CD:FGF7 complex and EV as an effective treatment to combat CRC.
    Matched MeSH terms: Solubility
  15. Al-Japairai KAS, Alkhalidi HM, Mahmood S, Almurisi SH, Doolaanea AA, Al-Sindi TA, et al.
    ACS Omega, 2020 Dec 22;5(50):32466-32480.
    PMID: 33376884 DOI: 10.1021/acsomega.0c04588
    Telmisartan suffers from low oral bioavailability due to its poor water solubility. The research work presents a formulation of solid dispersed (SD) telmisartan formulation as a ternary mixture of a drug, a polymeric carrier (poly(vinylpyrrolidone) (PVP) K30), and an alkalizer (Na2CO3). The preparation method, which was lyophilization of an aqueous solution containing the ingredients, was free from any organic solvent. The developed SD formulations resulted in a significant improvement in in vitro dissolution (>90% drug dissolution in 15 min) compared to pure telmisartan. Solid-state characterization by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) studies indicated the conversion of crystalline telmisartan into an amorphous form. Fourier transform infrared (FTIR) spectroscopy revealed the drug-polymer interaction that was responsible for reducing the chances of recrystallization. A short-term stability study showed that selected SD formulations were stable in terms of in vitro dissolution and retained their amorphous structure in ambient and accelerated conditions over 2 months. Selected formulations (drug/PVP K30/Na2CO3 as 1:1:2 or 1:2:2 weight ratio) resulted in >2.48 times relative oral bioavailability compared to marketed formulations. It was considered that the incorporation of an alkalizer and a hydrophilic polymer, and amorphization of telmisartan by lyophilization, could enhance in vitro dissolution and improve oral bioavailability.
    Matched MeSH terms: Solubility
  16. Pal A, Roy S, Kumar A, Mahmood S, Khodapanah N, Thomas S, et al.
    ACS Omega, 2020 Aug 18;5(32):19968-19977.
    PMID: 32832751 DOI: 10.1021/acsomega.0c01228
    This present study investigated the effect of Captisol, a chemically modified cyclodextrin, on the in vitro dissolution of glimepiride. We prepared glimepiride-Captisol complexes of different mass ratios (1:1, 1:2, and 1:3 w/w) by a physical mixing or freeze-drying technique, and found that complexation with Captisol enhanced the water solubility of glimepiride. Molecular docking and dynamic simulation predicted complex formation; at the same time, Fourier transform infrared spectroscopy, differential scanning calorimetry, powder X-ray diffractometry, and scanning electron microscope indicated molecular interactions that support complexation. We also found that an inclusion complex was better than a physical mixture in enhancing the complexation of glimepiride with Captisol and enhancing water solubility. Phase solubility study of the glimepiride-Captisol complex showed an AL-type profile, implying the formation of a 1:1 inclusion complex. The study also revealed that pH influenced the stability of the complex because the stability constant of the glimepiride-Captisol complex was higher in distilled water of pH ∼6.0 than in phosphate buffer of pH 7.2.
    Matched MeSH terms: Solubility
  17. Moradpour N, Karimova M, Pourafshary P, Zivar D
    ACS Omega, 2020 Jul 28;5(29):18155-18167.
    PMID: 32743190 DOI: 10.1021/acsomega.0c01766
    The results of many previous studies on low salinity/controlled ions water (CIW) flooding suggest that future laboratory and modeling investigations are required to comprehensively understand and interpret the achieved observations. In this work, the aim is co-optimization of the length of the injected slug and soaking time in the CIW flooding process. Furthermore, the possibility of the occurrence of several governing mechanisms is studied. Therefore, the experimental results were utilized to develop a compositional model, using CMG GEM software, in order to obtain the relative permeability curves by history matching. It was concluded that CIW slug injection, concentrated in the potential-determining ion, can increase oil recovery under a multi ion exchange (MIE) mechanism. The wettability of the carbonate rocks was changed from a mixed or oil wet state toward more water wetness. However, there is a CIW slug length, beyond which extending the length does not significantly improve the rock wettability, and consequently, the oil production, which is known as the optimum slug size. This implies that the optimization of the injection process, by minimizing the slug size, can decrease the need for the CIW supply, therefore lowering the process expenditure. Moreover, if the exposure time of the rock and CIW is increased (soaking), a higher level of ion substitution is probable, leading to more oil detachment and production. Rock dissolution/precipitation (leading to a pH change) was found to have a negligible contribution.
    Matched MeSH terms: Solubility
  18. Shazni Mohammad Haniff MA, Zainal Ariffin NH, Ooi PC, Mohd Razip Wee MF, Mohamed MA, Hamzah AA, et al.
    ACS Omega, 2021 May 11;6(18):12143-12154.
    PMID: 34056368 DOI: 10.1021/acsomega.1c00841
    We report a practical chemical vapor deposition (CVD) route to produce bilayer graphene on a polycrystalline Ni film from liquid benzene (C6H6) source at a temperature as low as 400 °C in a vertical cold-wall reaction chamber. The low activation energy of C6H6 and the low solubility of carbon in Ni at such a low temperature play a key role in enabling the growth of large-area bilayer graphene in a controlled manner by a Ni surface-mediated reaction. All experiments performed using this method are reproducible with growth capabilities up to an 8 in. wafer-scale substrate. Raman spectra analysis, high-resolution transmission electron microscopy, and selective area electron diffraction studies confirm the growth of Bernal-stacked bilayer graphene with good uniformity over large areas. Electrical characterization studies indicate that the bilayer graphene behaves much like a semiconductor with predominant p-type doping. These findings provide important insights into the wafer-scale fabrication of low-temperature CVD bilayer graphene for next-generation nanoelectronics.
    Matched MeSH terms: Solubility
  19. Eghbali Babadi F, Yunus R, Masoudi Soltani S, Shotipruk A
    ACS Omega, 2021 May 04;6(17):11144-11154.
    PMID: 34056270 DOI: 10.1021/acsomega.0c04353
    In this study, a mineral-based coated urea was fabricated in a rotary pan coater using a mixture of gypsum/sulfur/zeolite (G25S25Z50) as an effective and low-cost coating material. The effects of different coating compositions on the dissolution rate of urea and the crushing strength and morphology of the coated urea were investigated. A 25:25:50 (wt %) mixture of gypsum/sulfur/zeolite (G25S25Z50) increased the coating effectiveness to 34.1% with the highest crushing strength (31.06 N). The effectiveness of coated urea was further improved to 46.6% with the addition of a microcrystalline wax (3%) as a sealant. Furthermore, the release mechanisms of various urea fertilizers were determined by fitting the release profiles with six mathematical models, namely, the zeroth-order, first-order, second-order, Higuchi, Ritger & Peppas, and Kopcha models. The results showed that the release mechanism of the uncoated urea and all other coated urea followed the Ritger & Peppas model, suggesting the diffusional release from nonswellable delivery systems. In addition, due to the increased mass-transfer resistance, the kinetic constant was decreased from 0.2233 for uncoated urea to 0.1338 for G25S25Z50-coated urea and was further decreased to 0.0985 when 3% Witcovar 146 sealant was applied.
    Matched MeSH terms: Solubility
  20. Zakiyah, L.K., Gui, M.M., Foo, R.S., Mohamed, A.R., Chai, S.P.
    ASM Science Journal, 2011;5(2):91-100.
    MyJurnal
    The functionalization of pristine CNTs is necessary for carbon nanotubes (CNTs) to be fully utilized, with the aim of increasing the nanotube reactivity and solubility in aqueous solutions. In this study, multi-walled carbon nanotubes (MWCNTs) were functionalized with a carboxylic group as this was an important step prior to application. The carboxylic group-functionalization was conducted through acid treatment, using sulphuric and nitric acids mixed at a ratio of 3:1 (v/v) and sonication for 30 min under different temperatures and time durations. The functionalization conditions of 50ºC x 5 h and 60ºC x 3 h were identified to be most suitable for introducing a carboxylic group onto the nanotube surfaces. The percentage of total weight loss due to the carboxylic group on the MWCNTs treated at 50ºC x 5 h and 60ºC x 3 h obtained from the thermogravimetric analysis was 13.26% and 13.76%, respectively. For both samples, peaks corresponding to the carboxylic group were identified in the FT-IR spectra. The changes in the morphology of the treated MWCNTs were also observed under SEM analysis.
    Matched MeSH terms: Solubility
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