In Situ Evaluation of the Polymer Concentration Distribution of Microphase-Separated Polyelectrolyte Hydrogels by the Microelectrode Technique

2021 ◽  
Author(s):  
Takuya Nishimura ◽  
Honglei Guo ◽  
Ryuji Kiyama ◽  
Yoshinori Katsuyama ◽  
Jian Ping Gong ◽  
...  
Keyword(s):  
Concentration Distribution ◽  
Polymer Concentration ◽  
Microelectrode Technique

scholarly journals Occurrence of Penta-Aromatic Hydrocarbons in Jaintia and Barail Group Mudstones, Northeastern Bengal Basin, Bangladesh

2014 ◽  
Vol 8 ◽  
pp. 105-112
Author(s):  
HM Zakir Hossain ◽  
Md Sultan-Ul-Islam ◽  
Quazi Hasna Hossain
Keyword(s):  
Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbons ◽  
Concentration Distribution ◽  
Gas Chromatography Mass Spectrometry ◽  
Bengal Basin ◽  
Drill Core ◽  
Environmental Condition ◽  
High Concentration ◽  
Biogenic Origin

In the present experiment, concentration, distribution and sources of penta-aromatic hydrocarbons in seven drill core and outcrop samples from Jaintia and Barail Group mudstones, northeastern Bengal Basin, Bangladesh have been studied. Gas chromatography-mass spectrometry (GC-MS) was used to obtain composition details about the sedimentary organic matter (OM). Mudstone samples were found to contain relatively high penta-aromatic hydrocarbon abundances in the lower Jaintia Group than in the overlying Barail Group. High concentration of perylene suggests terrigenous sources and significantly higher content of total organic carbon in the samples. A biogenic origin of perylene therefore indicates oxygen deficient environmental condition for deposition of OM. Perylene over pentacyclic aromatic hydrocarbon isomers regulating in-situ diagenetic origin. DOI: http://dx.doi.org/10.3329/jles.v8i0.20154 J. Life Earth Sci., Vol. 8: 105-112, 2013

scholarly journals IN SITU GEL AS PLATFORM FOR KETOCONAZOLE SLOW RELEASE DOSAGE FORM

2018 ◽  
Vol 10 (5) ◽  
pp. 76
Author(s):  
Methaq Hamad Sabar ◽  
Iman Sabah Jaafar ◽  
Masar Basim Mohsin Mohamed
Keyword(s):  
Drug Release ◽  
Guar Gum ◽  
Polymer Concentration ◽  
Hydroxypropyl Methylcellulose ◽  
In Vitro Release ◽  
High Viscosity ◽  
In Situ Gel ◽  
Alginate Concentration

Objective: The aim of this study was to formulate ketoconazole (keto) as oral floating in situ gel to slow the release of keto in the stomach.Methods: Sodium alginate (Na alginate) was used as a primary polymer in the preparation of the in situ gel and was supported by the following polymers: guar gum (GG), hydroxypropyl methylcellulose (HPMC) K4M, K15M and carbapol 940 as viscosity enhancing agents. As a consequence, and to complete the gelation process of above formulations was by adding the calcium carbonate (CaCO3). The in situ gels were investigated by the following tests: floating lag time, floating duration, viscosity, drug content, in vitro gelling studies and in vitro release study.Results: The study showed that the faster release was obtained with F1 which contained Na alginate alone. Additionally, reduction in Na alginate concentration resulted in significant increase in drug release. It was also noted that the increase in GG (viscosity enhancing polymer) concentration resulted in non-significant decrease in percent drug release and the reduction in CaCO3 concentration led to significant increase in drug release. Moreover, the release of drug was also affected by grade of viscosity enhancing polymer, the faster release was observed with the formula which contained a polymer of low viscosity (HPMC K4M) and an opposite result was with the high viscosity polymer (HPMCK15M).Conclusion: This study showed the formulation of Na alginate with GG and CaCO3, led to gain floating in situ gel and a sustained release of keto. 

Three-Dimensional Zinc Mapping inside Aluminum Foams Using Synchrotron X-Ray Microtomography

2007 ◽  
Vol 561-565 ◽  
pp. 1677-1680 ◽  
Author(s):  
Tomomi Ohgaki ◽  
Y. Takami ◽  
Hiroyuki Toda ◽  
Toshiro Kobayashi ◽  
Y. Suzuki ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Cell Wall ◽  
Concentration Distribution ◽  
Three Dimensional ◽  
Aluminum Foams ◽  
X Ray ◽  
Precipitated Phase ◽  
Zn Concentration ◽  
In Situ Experiments

Three-dimensional zinc mapping based on X-ray K-edge scanning has been performed. By microtomographies with energies above and below the K-absorption edges of the elements, the concentration distribution of the elements is evaluated during in-situ experiments, respectively. It is found that the Zn concentration distribution during the heat treatment was changed inside the cell wall of the aluminum foams and it has been homogenized. Also several precipitated phase transformation can be three-dimensionally visualized by the CT-method tuning X-ray energies.

scholarly journals Shrinking, Growing, and Bursting: Microfluidic Equilibrium Control of Water-in-Water Droplets

2021 ◽  
Author(s):  
Byeong-Ui Moon ◽  
Dae Kun Hwang ◽  
Scott S. H. Tsai
Keyword(s):  
Dynamic Equilibrium ◽  
Polymer Concentration ◽  
Dynamic Control ◽  
Microfluidic Channel ◽  
Continuous Phase ◽  
Phase System ◽  
Two Phase ◽  
Equilibrium Control ◽  
Tie Lines

We demonstrate the dynamic control of aqueous two phase system (ATPS) droplets in shrinking, growing, and dissolving conditions. The ATPS droplets are formed passively in a flow focusing microfluidic channel, where the dextran-rich (DEX) and polyethylene glycol-rich (PEG) solutions are introduced as disperse and continuous phases, respectively. To vary the ATPS equilibrium condition, we infuse into a secondary inlet the PEG phase from a different polymer concentration ATPS. We find that the resulting alteration of the continuous PEG phase can cause droplets to shrink or grow by approximately 45 and 30 %, respectively. This volume change is due to water exchange between the disperse DEX and continuous PEG phases, as the system tends towards new equilibria. We also develop a simple model, based on the ATPS binodal curve and tie lines, that predicts the amount of droplet shrinkage or growth, based on the change in the continuous phase PEG concentration. We observe a good agreement between our experimental results and the model. Additionally, we find that, when the continuous phase PEG concentration is reduced such that PEG and DEX phases no longer phase separate, the ATPS droplets are dissolved into the continuous phase. We apply this method to controllably release encapsulated microparticles and cells, and we find that their release occurs within 10 seconds. Our approach uses the dynamic equilibrium of ATPS to control droplet size along the microfluidic channel. By modulating the ATPS equilibrium, we are able to shrink, grow, and dissolve ATPS droplets in situ. We anticipate that this approach may find utility in many biomedical settings, for example, in drug and cell delivery and release applications.

In-Situ Gelling System based on Thiolated Gellan Gum as New Carrier for Nasal Administration of Dimenhydrinate

2009 ◽  
Vol 2 (2) ◽  
pp. 544-550
Author(s):  
Hitendra Mahajan ◽  
Hannan Shaikh ◽  
Surendra Gattani ◽  
Pankaj Nerkar
Keyword(s):  
Nasal Mucosa ◽  
Histopathological Examination ◽  
Polymer Concentration ◽  
Gellan Gum ◽  
Nasal Administration ◽  
In Vitro Permeation ◽  
Permeation Studies ◽  
In Situ Gelling

The purpose of the present study was to develop intranasal delivery system of dimenhydrinate using thiolated gellan gum and formulations were modulated so as to have gelation at physiological ion content after intranasal administration.  Gelation was determined by physical appearance.  The mucoadhesive force in terms of detachment stress, determined using sheep nasal mucosa, increased with increasing concentration of thiolated polymer. The results of in vitro drug permeation studies across sheep nasal mucosa indicate that effective permeation could be significantly increased by using in situ gelling formulation with thiolated polymer concentration.  Finally, histopathological examination did not detect any changes during in vitro permeation studies.  In conclusion the gel formulation of dimenhydrinate with in situ gelling and mucoadhesive properties with increased permeation rate is promising for prolonging nasal residence time and thereby nasal absorption.

scholarly journals FORMULATION AND EVALUATION OF FLOATING ORAL IN SITU GEL OF DILTIAZEM HYDROCHLORIDE

2016 ◽  
Vol 9 (1) ◽  
pp. 50
Author(s):  
A. Maheswaran ◽  
J. Padmavathy ◽  
V. Nandhini ◽  
D. Saravanan ◽  
P. Angel
Keyword(s):  
Drug Release ◽  
Sodium Alginate ◽  
Polymer Concentration ◽  
Methyl Cellulose ◽  
Diltiazem Hydrochloride ◽  
Release Formulation ◽  
Gelling Properties ◽  
In Situ Gelling

Objective: The objective of the present study was to formulate and evaluate the floating in-situ gelling system of diltiazem hydrochloride.Methods: Sodium alginate based diltiazem hydrochloride floating in situ gelling systems were prepared by dissolving hydroxyl propyl methyl cellulose (HPMC) in 25% of water, to which calcium carbonate and diltiazem hydrochloride were added with stirring to form, a proper and a homogenous dispersion of diltiazem hydrochloride. Meanwhile, 30% of water was heated to 60 ˚C on a hot plate to dissolve sodium alginate and cooled to 40 ˚C. The resulting solution was added to HPMC solution and mixed well. To 5% of water at 60 ˚C, sodium methyl paraben was added and dissolved and cooled to 40 ˚C and was added to the above mixture and mixed well. The volume was adjusted finally to 100% with distilled water. Prepared formulae were evaluated for physicochemical properties, drug content, pH, in vitro gelling capacity, in vitro buoyancy, viscosity, water uptake and in vitro drug release.Results: Formulation variables such as type and concentration of viscosity enhancing polymer (sodium alginate) and HPMC affected the formulation viscosity, gelling properties, floating behavior, and in vitro drug release. Formulation F5 and F6 showed the floating time of 5 min and more than 20 h respectively. A significant decrease in the rate and extent of the drug release was observed with the increase in polymer concentration in in-situ gelling preparation. Formulation F4, F5, F6 were shown to have extended drug release until the end of 7 h.Conclusion: The prepared in situ gelling formulations of diltiazem hydrochloride could float in the gastric conditions and released the drug in a sustained manner. The present formulation was non-irritant, easy to administer along with good retention properties, better patient compliant and with greater efficacy of the drug.

scholarly journals FORMULATION AND EVALUATION OF IN-SITU GEL CONTAINING LINEZOLID IN THE TREATMENT OF PERIODONTITIS

2021 ◽  
pp. 79-86
Author(s):  
INAYATHULLA . ◽  
PRAKASH GOUDANAVAR ◽  
MOHAMMAD ALI ◽  
SHAHID UD DIN WANI ◽  
NAGARAJA SREEHARSHA
Keyword(s):  
Drug Release ◽  
Polymer Concentration ◽  
Hydroxypropyl Methylcellulose ◽  
In Vitro Release ◽  
In Situ Gel ◽  
Diffusion Controlled ◽  
Gelling Time ◽  
Carbopol 934P

Objective: The intent to prepare and evaluate Linezolid in-situ gel in the treatment of periodontitis. Methods: pH-sensitive in-situ gel was formed by the cold method using a varying concentration of the drug, carbopol 934P and hydroxypropyl methylcellulose (HPMC) and carbopol 934P and sodium carboxy methylcellulose (CMC) (1:1,1:1.5,1:2,1:2.5). An optimized batch was selected based on gelling time and gelling capacity. The prepared in-situ gels were evaluated for appearance, pH, gelling capacity, viscosity, in vitro release studies, rheological studies, and finally, was subjected to drug content estimation and antibacterial activity test. Results: FTIR study shows drug and physical mixture were compatible with each other. The rheology of formulated in-situ gel exhibited a pseudoplastic flow pattern. this may be because when polymer concentration was increased the prepared formulations become more viscous and in turn delayed the drug release and from the prepared formulation, LF4 and SF4 have polymer concentrations i. e, 0.9% carbopol and sodium CMC showed drug release up to 12 h. Conclusion: When carbopol is appropriately mixed with other suitable polymers it forms an in-situ gel-forming system that was substantiated by the property to transform into stiff gels when the pH is increased. The in-situ gel was prepared using a combination of carbopol-HPMC and carbopol-Na CMC The formulations LF1 to SF4 showed high linearity (R2 = 0.490-0.682), indicating that the drug was released from the prepared in-situ gel by the diffusion-controlled mechanism. Thus, the formulation of batches LF4 and SF4 containing carbopol: HPMC and carbopol: NaCMC in 1:2 ratios were considered as optimum formulation based on optimum viscosity, gelling capacity and to extend the in vitro drug release.

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