scholarly journals Characterizing the Influence of Organic Polymers on the Specific Reactivity of Particulate Remedial Amendments

2021 ◽  
Vol 9 ◽  
Author(s):  
Katherine A. Muller ◽  
Lirong Zhong ◽  
Christopher E. Bagwell
Keyword(s):  
Performance Metrics ◽  
Guar Gum ◽  
Polymer Solutions ◽  
Chemical Reduction ◽  
Polymer Concentration ◽  
Predictive Performance ◽  
Water Soluble ◽  
High Mass ◽  
Organic Polymers ◽  
Treatment Rate

Commercially available particulate amendments demonstrate high reactivity for effective treatment of water soluble organic and inorganic contaminants in laboratory studies; however, transport of these particles is constrained in the subsurface. In many field applications, particulate amendments are mixed with organic polymers to enhance mobility for direct push applications or stabilize suspensions for high mass loadings. As such, the interactions between particulate amendments, organic polymers and contaminant species need to be systematically investigated to properly understand mechanistic processes that facilitate predictive performance metrics for specific applications in situ. In this study, batch experiments were conducted to quantify the effects of organic polymers (xanthan gum, guar gum, and sodium alginate), polymer concentration (800 and 4,000 mg/L), and aging (up to 28 days) on chromate treatment rate and capacity by two classes of amendments: reductants [granular zero-valent iron (gZVI), micron-ZVI (mZVI), sulfur modified iron (SMI)], and an adsorbent (bismuth sub-nitrate). When particulate amendments were suspended in polymer solutions, reductants retained between 84–100% of the amendment treatment capacity. Conversely, the adsorbent maintained 63–97% relative treatment capacity of the no-polymer control. Polymer solutions had a more pronounced impact on the rate of chromate removal; first order rates of chemical reduction decreased by as much as 70% and adsorption by up to 81% relative to the no-polymer controls. Polymer–amendment aging experiments also showed decreased Cr(VI) treatment capacity; reductants decreased by as much as 24% and adsorption decreased by as much as 44% after 28 days of incubation. While polymer suspensions are needed to aid the injection of particulate amendments into the subsurface, the results from this study indicate potential losses of treatment capacity and a decrease in the rate of remedial performance due to the physical and chemical interactions between polymer suspensions and reactive particulate amendments. Simple batch systems provide baseline characterization of tripartite interactions for the removal of Cr(VI). Additional work is needed to quantify the full impact of polymers on remedial outcomes under site relevant conditions at field scale.

Functional Poly(p-Xylylene)s via Chemical Reduction of Poly(p-Phenylene Vinylene)s

2019 ◽  
Author(s):  
Ain Uddin ◽  
Weifan Sang ◽  
Yong Gao ◽  
Kyle Plunkett
Keyword(s):  
Film Formation ◽  
Chemical Reduction ◽  
Water Soluble ◽  
Phenylene Vinylene ◽  
Polymer Modification ◽  
Polymer Backbone ◽  
Crosslinking Process ◽  
Conducting Membranes ◽  
In Situ Crosslinking

The synthesis of poly(p-xylylene)s (PPXs) with sidechains containing alkyl bromide functionality, and their post-polymer modification, is described. The PPXs were prepared by a diimide hydrogenation of poly(p-phenylene vinylene)s (PPVs) that were originally synthesized by a Gilch polymerization. The polymer backbone reduction was carried out with hydrazine hydrate in toluene at 80 °C to provide polymers with the sidechain-containing bromide functionality intact. To demonstrate post-polymer modification of the sidechains, the resulting PPX polymers were modified with trimethylamine to form tetraalkylammonium ion functionality and were evaluated as anion conducting membranes. While PPX homopolymers containing tetralkylammonium ions were completely water soluble and not able to form valuable films, PPX copolymers containing mixed tetraalkylammonium ions and hydrophobic chains were capable of film formation and alkaline stability. In addition, an in situ crosslinking process that used N,N,N',N'-tetramethyl-1,6-hexanediamine during the tetraalkylammonium formation of brominated PPX polymers was also evaluated and gave reasonable films with conductivities of ~10 mS-cm-1.

Functional Poly(p-Xylylene)s via Chemical Reduction of Poly(p-Phenylene Vinylene)s

2019 ◽  
Author(s):  
Ain Uddin ◽  
Weifan Sang ◽  
Yong Gao ◽  
Kyle Plunkett
Keyword(s):  
Film Formation ◽  
Chemical Reduction ◽  
Water Soluble ◽  
Phenylene Vinylene ◽  
Polymer Modification ◽  
Polymer Backbone ◽  
Crosslinking Process ◽  
Conducting Membranes ◽  
In Situ Crosslinking

The synthesis of poly(p-xylylene)s (PPXs) with sidechains containing alkyl bromide functionality, and their post-polymer modification, is described. The PPXs were prepared by a diimide hydrogenation of poly(p-phenylene vinylene)s (PPVs) that were originally synthesized by a Gilch polymerization. The polymer backbone reduction was carried out with hydrazine hydrate in toluene at 80 °C to provide polymers with the sidechain-containing bromide functionality intact. To demonstrate post-polymer modification of the sidechains, the resulting PPX polymers were modified with trimethylamine to form tetraalkylammonium ion functionality and were evaluated as anion conducting membranes. While PPX homopolymers containing tetralkylammonium ions were completely water soluble and not able to form valuable films, PPX copolymers containing mixed tetraalkylammonium ions and hydrophobic chains were capable of film formation and alkaline stability. In addition, an in situ crosslinking process that used N,N,N',N'-tetramethyl-1,6-hexanediamine during the tetraalkylammonium formation of brominated PPX polymers was also evaluated and gave reasonable films with conductivities of ~10 mS-cm-1.

scholarly journals Laboratory Testing of Fracture Conductivity Damage by Foam-Based Fracturing Fluids in Low Permeability Tight Gas Formations

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1783
Author(s):  
Klaudia Wilk-Zajdel ◽  
Piotr Kasza ◽  
Mateusz Masłowski
Keyword(s):  
Hydraulic Fracturing ◽  
Guar Gum ◽  
Polymer Concentration ◽  
Laboratory Research ◽  
Damage Effect ◽  
Tight Gas ◽  
Fracturing Fluid ◽  
Fracture Conductivity ◽  
Fracturing Fluids ◽  
Sandstone Rock

In the case of fracturing of the reservoirs using fracturing fluids, the size of damage to the proppant conductivity caused by treatment fluids is significant, which greatly influence the effective execution of hydraulic fracturing operations. The fracturing fluid should be characterized by the minimum damage to the conductivity of a fracture filled with proppant. A laboratory research procedure has been developed to study the damage effect caused by foamed and non-foamed fracturing fluids in the fractures filled with proppant material. The paper discusses the results for high quality foamed guar-based linear gels, which is an innovative aspect of the work compared to the non-foamed frac described in most of the studies and simulations. The tests were performed for the fracturing fluid based on a linear polymer (HPG—hydroxypropyl guar, in liquid and powder form). The rheology of nitrogen foamed-based fracturing fluids (FF) with a quality of 70% was investigated. The quartz sand and ceramic light proppant LCP proppant was placed between two Ohio sandstone rock slabs and subjected to a given compressive stress of 4000–6000 psi, at a temperature of 60 °C for 5 h. A significant reduction in damage to the quartz proppant was observed for the foamed fluid compared to that damaged by the 7.5 L/m3 natural polymer-based non-foamed linear fluid. The damage was 72.3% for the non-foamed fluid and 31.5% for the 70% foamed fluid, which are superior to the guar gum non-foamed fracturing fluid system. For tests based on a polymer concentration of 4.88 g/L, the damage to the fracture conductivity by the non-foamed fluid was 64.8%, and 26.3% for the foamed fluid. These results lead to the conclusion that foamed fluids could damage the fracture filled with proppant much less during hydraulic fracturing treatment. At the same time, when using foamed fluids, the viscosity coefficient increases a few times compared to the use of non-foamed fluids, which is necessary for proppant carrying capacities and properly conducted stimulation treatment. The research results can be beneficial for optimizing the type and performance of fracturing fluid for hydraulic fracturing in tight gas formations.

Formulation and Evaluation of Benidipine Nanosuspension

2021 ◽  
pp. 4111-4116
Author(s):  
Sejal Patel ◽  
Anita P. Patel
Keyword(s):  
Particle Size ◽  
Water Solubility ◽  
Polymer Concentration ◽  
Oral Route ◽  
Water Soluble ◽  
In Vitro Dissolution ◽  
Scanning Calorimetry ◽  
23 Factorial Design ◽  
Selection Of

In the interest of administration of dosage form oral route is most desirable and preferred method. After oral administration to get maximum therapeutic effect, major challenge is their water solubility. Water insoluble drug indicate insufficient bioavailability as well dissolution resulting in fluctuating plasma level. Benidipine (BND) is poorly water soluble antihypertensive drug has lower bioavailability. To improve bioavailability of Benidipine HCL, BND nanosuspension was formulated using media milling technique. HPMC E5 was used to stabilize nanosuspension. The effect of different important process parameters e.g. selection of polymer concentration X1(1.25 mg), stirring time X2 (800 rpm), selection of zirconium beads size X3 (0.4mm) were investigated by 23 factorial design to accomplish desired particle size and saturation solubility. The optimized batch had 408 nm particle size Y1, and showed in-vitro dissolution Y2 95±0.26 % in 30 mins and Zeta potential was -19.6. Differential scanning calorimetry (DSC) and FT-IR analysis was done to confirm there was no interaction between drug and polymer.

A robust framework for shoulder implant X-ray image classification

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Minh Thanh Vo ◽  
Anh H. Vo ◽  
Tuong Le
Keyword(s):  
Image Classification ◽  
Performance Metrics ◽  
State Of The Art ◽  
Area Under The Curve ◽  
Predictive Performance ◽  
Extraction Process ◽  
Content Type ◽  
X Ray ◽  
Robust Model ◽  
Input Dataset

PurposeMedical images are increasingly popular; therefore, the analysis of these images based on deep learning helps diagnose diseases become more and more essential and necessary. Recently, the shoulder implant X-ray image classification (SIXIC) dataset that includes X-ray images of implanted shoulder prostheses produced by four manufacturers was released. The implant's model detection helps to select the correct equipment and procedures in the upcoming surgery.Design/methodology/approachThis study proposes a robust model named X-Net to improve the predictability for shoulder implants X-ray image classification in the SIXIC dataset. The X-Net model utilizes the Squeeze and Excitation (SE) block integrated into Residual Network (ResNet) module. The SE module aims to weigh each feature map extracted from ResNet, which aids in improving the performance. The feature extraction process of X-Net model is performed by both modules: ResNet and SE modules. The final feature is obtained by incorporating the extracted features from the above steps, which brings more important characteristics of X-ray images in the input dataset. Next, X-Net uses this fine-grained feature to classify the input images into four classes (Cofield, Depuy, Zimmer and Tornier) in the SIXIC dataset.FindingsExperiments are conducted to show the proposed approach's effectiveness compared with other state-of-the-art methods for SIXIC. The experimental results indicate that the approach outperforms the various experimental methods in terms of several performance metrics. In addition, the proposed approach provides the new state of the art results in all performance metrics, such as accuracy, precision, recall, F1-score and area under the curve (AUC), for the experimental dataset.Originality/valueThe proposed method with high predictive performance can be used to assist in the treatment of injured shoulder joints.

scholarly journals Direct-Write Drawing of Carbon Nanotube/Polymer Composite Microfibers

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Scott M. Berry ◽  
Santosh Pabba ◽  
Robert W. Cohn ◽  
Robert S. Keynton
Keyword(s):  
Carbon Nanotube ◽  
Polymer Solutions ◽  
Fiber Diameter ◽  
Axial Strain ◽  
Polymer Concentration ◽  
Strain Rates ◽  
Direct Write ◽  
Composite Fibers ◽  
Capillary Thinning ◽  
Doped Polymer

Carbon-nanotube- (CNT-) doped polymer solutions were drawn into arrays of microfibers using a novel direct-write process. This process utilizes a micromanipulator-controlled syringe loaded with solvated polymer mixed with CNTs to “write” networks of composite fibers with precisely positioned endpoints. The diameters of these composite fibers are correlated to the degree of capillary thinning that occurs prior to the solidification of the directly written CNT-doped solution filament. The fibers had diameters ranging from 7 μm to over 100 μm and possessed conductivities as high as 0.1 Sm−1. Fiber diameter was found to increase with increasing polymer concentration and decreasing fiber length and can be controlled through modulation of these parameters. The presence of CNTs was found not to significantly affect fiber diameter, despite the CNTs significant effect on viscosity, which was previously reported to influence diameter. This discrepancy is likely related to the non-Newtonian effects of CNT/polymer solutions, including an apparent shear thinning at increasing axial strain rates.

Flow of Hydrophobically Modified Water-Soluble-Polymer Solutions in Porous Media: New Experimental Insights in the Diluted Regime

SPE Journal ◽  
2010 ◽  
Vol 16 (01) ◽  
pp. 43-54 ◽  
Author(s):  
Guillaume Dupuis ◽  
David Rousseau ◽  
René Tabary ◽  
Bruno Grassl
Keyword(s):  
Oil Recovery ◽  
Polymer Concentration ◽  
Adsorbed Layer ◽  
Water Soluble ◽  
Water Soluble Polymer ◽  
Improved Oil Recovery ◽  
Water Soluble Polymers ◽  
Resistance Factors ◽  
Soluble Polymers ◽  
Hydrophobically Modified

Summary The specific molecular structure of hydrophobically modified water-soluble polymers (HMWSPs), also called hydrophobically associative polymers, gives them interesting thickening and surface-adsorption abilities compared with classical water-soluble polymers (WSPs), which could be useful in polymer-flooding and well-treatment operations. However, their strong adsorption obviously can impair their injectivity, and, conversely, the shear sensitivity of their gels can be detrimental to well treatments. Determining for which improved-oil-recovery (IOR) application HMWSPs are best suited, therefore, remains difficult. The aim of this work is to bring new insight regarding the interaction mechanisms between HMWSPs and rock matrix and the consequences concerning their propagation in reservoirs. A consistent set of HMWSPs with sulfonated polyacrylamide backbones and alkyl hydrophobic side chains together with an equivalent WSP was synthesized and fully characterized. HMWSP and WSP solutions were then injected in model granular packs. As expected, with HMWSPs, high resistance factors (or mobility reductions, Rm) were observed. Yet, within the limit of the injected volumes, the effluent showed the same viscosity and polymer concentration as the injected solutions. A first significant outcome concerns the specificities of the Rm curves during HMWSP injections. Rm increases took place in two steps. The first corresponded to the propagation of the viscous front, as observed with WSP, whereas the second was markedly delayed, occurring several pore volumes (PV) after the breakthrough. This result is not compatible with the classical picture of multilayer adsorption of HMWSPs but suggests that injectivity is controlled solely by the adsorption of minor polymeric species. This hypothesis was confirmed by reinjecting the collected effluents into fresh cores; no second-step Rm increases were observed. Brine injections in HMWSP-treated cores revealed high residual resistance factors (or irreversible permeability reductions, Rk), which can be attributed to the presence of thick polymer-adsorbed layers on the pore surface. Nevertheless, Rk values strongly decreased when increasing the brine-flow rate. This second significant outcome shows that the adsorbed-layer thickness is shear-controlled. These new results should lead to proposing new adapted filtration and injection procedures for HMWSPs, aimed, in particular, at improving their injectivity.

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. 

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