Gel Solution Research Articles

Encapsulation of SOD in chitosan-coated gel particles of alginate or mixture of alginate and shellac for targeted intestinal delivery

The chitosan-coated alginate gel particles (CS/SA) and chitosan-coated alginate-shellac gel particles (CS/SA/Lac) were constructed to serve as a potential oral delivery system to enhance the stability and activity of superoxide dismutase (SOD) in this study. The encapsulation efficiency (EE), enzyme activity retention ratio (ER), particle structure, and SOD release behavior, as well as the effect of shellac, were evaluated. The best formula is determined by the percentage of total effective activity (PTEA).The results showed that CS/SA prepared by 0.30‰ chitosan, 1.00% CaCl2, 2.00% sodium alginate (M/G = 1:1, Mw: 38,857 kDa), and gelation solution pH 5.50 had the best chitosan shell, the strongest gel structure and the maximum PTEA which was 10.75 ± 1.45%. Based on the optimal formula, addition of shellac that formed shellac-Ca2+ microspheres in the gel network was averse to SOD encapsulation, but it significantly improved the stability of SOD in gastric conditions. By adding 15.00% shellac, the PTEA reached 16.30 ± 1.64%. At optimal formulation, SOD encapsulated in CS/SA was completely released in the stimulated intestinal fluid and accumulative release enzyme activity (EA) was 966.62 ± 103.75 (U) after 6 h. However, the CS/SA/Lac with a low swelling ratio only released SOD in stimulated colonic fluid and the EA value reached 1692.28 ± 101.82 (U) after 1 h. These findings demonstrated that CS/SA and CS/SA/Lac were excellent candidates for SOD oral administration, which was useful in the food and biomedical industries for developing functional products containing SOD.

Nanopatterned rGO/ZnO:Al seed layer for vertical growth of single ZnO nanorods

In this work, we demonstrate a novel low-cost template-assisted route to synthesize vertical ZnO nanorod arrays on Si (100). The nanorods were grown on a patterned double seed layer comprised of reduced graphene oxide (rGO) and Al-doped ZnO nanoparticles. The seed layer was fabricated by spray-coating the substrate with graphene and then dip-coating it into a Al-doped ZnO sol–gel solution. The growth template was fabricated from a double-layer resist, spin-coated on top of the rGO/ZnO:Al seed layer, and patterned by colloidal lithography. The results show a successful chemical bath deposition of vertically aligned ZnO nanorods with controllable diameter and density in the nanoholes in the patterned resist mask. Our novel method can presumably be used to fabricate electronic devices on virtually any smooth substrate with a thermal budget of 1 min at 300 °C with the seed layer acting as a conductive strain-relieving back contact. The top contact can simply be made by depositing a suitable transparent conductive oxide or metal, depending on the specific application.

Effects of adding curcumin-loaded halloysite nanotubes to Nile tilapia skin gelatin film re-crosslinked with tannic acid

An alternative for the recovery of waste from tilapia skin would be the development of biomaterials, such as gelatin-based films, which could be applied in the area of tissue engineering. One strategy for this is to use crosslinking processes and add reinforcement, such as haloysite nanotubes (Hal), in order to improve its mechanical, chemical and structural properties. Thus, films were obtained by the casting method using Hal loaded with curcumin (Hal-Cur) as dispersed phase (reinforcement), tilapia skin gelatin (Gel) acting as matrix and tannic acid (TA) as crosslinker. The films were characterized by analyzing the degree of crosslinking, antioxidant activity, FT-IR, TGA, DMA, mechanical assays, SEM, contact angle, water vapor permeability and cytotoxicity. Regarding the structure of these materials, the pH adjustment in the Gel solution to 11 (> IP) favored the formation of possible hydrogen bonds between the -OH groups of the Hal-Cur and TA with the -NH2 and -OH groups of the Gel. With the addition of Hal-Cur, the films crosslinked with TA showed greater flexibility, moderate hydrophilicity, high antioxidant activity (67.88–70.01%) and greater permeability to water vapor, in addition to excellent biocompatibility (cellular viability >75%). In addition, they obtained an adequate water vapor transmission rate to act in wound healing. Therefore, these films have the potential to be used as biodressings in the treatment of epidermal lesions.

Development, QbD based optimization and in vitro characterization of Diacerein loaded nanostructured lipid carriers for topical applications

ObjectiveDCN is a chondro-protective agent which displays inadequate oral bioavailability along with gastrointestinal side effects. It is a choice of drug for treatment of osteoarthritis. Therefore, the objective of this study was to develop and optimize DCN loaded nanostructured lipid carrier (NLCs) for topical delivery. MethodNLCs were prepared by hot homogenization followed by sonication method. The formulation was optimized by 2 factor 3 level central composite design taking two independent variables i.e. concentration of stearic acid (A) and concentration of oleic acid (B), and three independent variables, particles size (Y1), % entrapment efficiency (Y2) and % drug release at 24 hours(Y3). ResultThe particle size, % entrapment efficiency and in-vitro drug release at 24 hours of optimized formulation was found 173.76 nm, 91.30%, and 94.17% respectively. The optimized DCN-NLC formulations were analyzed by DSC and XRD, TEM, and FTIR studies. DCN-NLC loaded gel was prepared and characterized for physical examination, viscosity and stability parameters. DCN-NLC in the gel form displayed sustained drug release and significant (p<0.05) tissue penetration in vitro in comparison to plain gel and DCN solution. The drug release kinetics study illustrated the Higuchi’s release pattern for prolonged period of time. Ex vivo permeation study result supported good topical penetration for DCN using DCN-NLCs. ConclusionConclusively, the developed formulation has potential for topical application for future pre-clinical studies.

Self-filling and plugging performance of a thixotropic polymer gel for lost circulation control in fractured formation

Drilling fluid loss in fractured formations hinders the progress of oil and gas exploration and its development worldwide. Improving the success rate of lost circulation control in fractured formations of oilfields worldwide is crucial for safe, efficient, and economical drilling. The thixotropy of gel solution is an important factor affecting the fracture space filling and plugging performance of thixotropic polymer gel. In this work, a thixotropic polymer gel with shear thinning and static thickening is used as a plugging agent for fractured formations. The self-filling behaviour and plugging performance of the gel in fractures were studied by visual physical simulation. The results showed that the thixotropic polymer gel was less affected by the fracture width when filling in the fracture, which could realize the uniform filling of the 12 mm wide fracture space. In addition, the thixotropic polymer gellant could be pumped in at high shear rates and retained in the loss space at low shear rates. Meanwhile, the plugging performance of the thixotropic gel on different scales of fractures was studied. Thixotropic polymer gel system could reside in different fracture types (uniform fracture, wedge-shaped fracture) and different fracture sizes. The breakthrough pressure of the thixotropic polymer gel in the wedge-shaped fracture was higher than that in the uniform fracture for identical outlet sizes. The thixotropic polymer gel had a pressure bearing capacity of 6.6 MPa in a wedge-shaped fracture with 5 mm width. The pressure bearing capacity of the gel to the wedge-shaped fracture with a width of 3 mm at the outlet reached 7.3 MPa, showed excellent pressure bearing capacity. The study on the self-filling behaviour and plugging performance of thixotropic polymer gel could provide theoretical and technical reference for efficient plugging in the drilling process of fractured formations.

Roll to roll triboelectric fiber manufacturing for smart-textile self-powered sensor and harvester

The integration of a multifunctional electronic textile-based triboelectric nanogenerator (TENG) with miniaturized devices has opened up a new horizon in the field of wearable electronics. Unfortunately, the development of textile based TENG has enormous shortcomings, including shortcomings in durability, stability, washability, and compatibility with mass production. Thus, this work reports a cost-effective, simple fabrication, and industrially scalable production method of producing fiber TENG using silver conductor fiber encapsulated by polydimethylsiloxane (PDMS). To produce continuous PDMS-coated silver fiber, a home-made coating technology was used, in which silver fiber was fed up through a nozzle filled with PDMS gel solution using a roll-to-roll continuous fabrication process. The feasibilities of TENG fiber production were demonstrated by the manufacturing of over 300-meter-long fibers and therefrom a half-meter-long TENG woven fabric of 20 cm width including the integration technique into wearable garments for self-powered sensors and harvesters. The maximum output open circuit voltage and short circuit current of the PDMS-coated silver triboelectric nanogenerator (PS-TENG) were ∼50 V and ∼8.0 μA from 50.0 cm-long and 0.55 mm diameter fiber. A PS-TENG coil harvester out of this fiber can easily light up 160 LEDs with simple hand tapping. We also demonstrated the PS-TENG integration on the heel of a shoe insole, which was also able to light up 25 LEDs in serial connection during walking. Furthermore, since the PS-TENG provides flexibility and excellent durability against washing, repeatable uses, rubbing, and stability in harsh chemical environments, we have also integrated the self-powered sensor fiber into various healthcare objects and wearable sports items, including hand gloves for cardiopulmonary resuscitation sensing (CPRS), a belt for respiration sensing, and a belt for football shoes and boxing gloves to evaluate the impact of kicking and boxing. All these advantages of PS-TENG not only enable small wearable electronics to be powered but also accelerate the development of industrially scalable energy harvesting through engineering design.

Transparent Films Thickness Mapping Highlighting the Viscosity Effect of Elastic Layers Made by Sol–Gel Process with an In-House Ellipsometer

New optical coatings are currently developed to mitigate the shockwave generated by nanosecond lasers in high-power laser systems such as the MegaJoule laser (LMJ). These shockwaves seem responsible for the damage growth observed on optical components. A possible solution for shockwave mitigation is using ormosil (organically modified silicate) coatings made by the sol–gel method with thicknesses of a few microns. Unfortunately, the sol–gel solution exhibits a viscous behavior, and thus, the deposited layers are heterogeneous in thickness. An experimental ellipsometer has been designed to measure this heterogeneity and highlight the viscoelastic properties of the layers responsible for self-healing effects that were observed when these layers were scratched. This ellipsometer allows us to know the refractive index of the coating and therefore its density. Density and thickness are the two essential parameters for determining the speed of sound and the modulus of elasticity of the layer, which indicate the ability of the layer to attenuate more or less elastic waves or shock waves.

Experimental Investigation on the Performance of Polymer-Coated Clay/Polyacrylamide Hydrogel for Water Shutoff Treatment

SummaryPolymer gel system has been identified as having the potential for blocking and diverting water flow. However, the current polymer reported an inability to maintain its mechanical strength, limited penetration depth, and instability in reservoir conditions of high temperature and high pressure. A distinctive bentonite nanomer clay (PGV)/acrylamide (AM)-co-2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) preformed particle gel with poly(ethylene glycol-b-tetramethylene oxide) (PEGTMO) coating to control the swelling kinetics is formulated. The in-house formulated gel’s ability to block and divert water flow in a porous medium is studied. The formation recipe of the gel was achieved by numerous swelling tests as induced by brine solution under reservoir conditions. Through the swelling tests, the long-term thermal stability of the gel solution was demonstrated. The incorporation of PGV clay particles improves the swelling and mechanical properties of the gel. Premature swelling can be avoided with PEGTMO coating as it slows the swelling rate over a 10-minute period, which gives the advantage of controlling the swelling before reaching the intended site of action during coreflood experiments. The rheological behavior of the hydrogel features rubber-like mechanical behavior with a viscosity value of 1.17 cp, which displayed water-like characteristics. Further, significant permeability reduction of large fractures is demonstrated by the coreflooding experiment with a calculated result of 96.2%. This formulated gel could offer the solution as a blocking agent in void space channels containing reservoirs that leads to a reduction of water cut due to thief zones.

A rapid and convenient enzyme digestion method for the analysis of N-glycans using exoglycosidase-impregnated polyacrylamide gels fabricated in an automatic pipette tip.

Efficient enzymatic digestion methods are critical for the characterization and identification of glycans. Glycan hydrolysis enzymes are widely utilized for the identification of glycoprotein or glycolipid glycans. The commonly utilized in solution glycan hydrolysis methods require several hours of incubation with enzymes for complete removal of their target monosaccharides. To develop an efficient and simple method for the rapid release of monosaccharides from glycoprotein glycans, we fabricated exoglycosidase-impregnated acrylamide gels in an automatic pipette tip. Our automated enzymatic reactors are based on the simple photochemical copolymerization of monomers comprising acrylamide and methylene-bis-acrylamide-containing enzymes with an azobis compound functioning as the photocatalytic initiator. After filling the tip of the automatic pipette with these acrylamide solutions, polymerization of the acrylamide gel solution was performed by irradiation with a LED. The immobilized enzymes maintained their activities in the pipette tips and their action was completed by fully automatic pipetting for 10 to 30min. We utilized 8-aminopyrene-1, 3, 6-trisulfonic acid (APTS)-labeled glycans as a substrate and measured by capillary electrophoresis (CE) before and after enzymatic digestion. We demonstrated that this method exhibited quantitative enzymatic and specific cleavage of monosaccharides from glycoprotein glycans.

Extraction of plastic nanoparticles using surface engineered kapok tubes from water

The nano- and microplastic particles from plastic wastes are emerging pollutants that cause significant harm to living organisms and the environment. Little is known on the removal of these emerging pollutants from water. The adsorbents reported to date have been designed to remove dissolved pollutants from water, such as dyes and heavy metals. Here, kapok tubes (KT) were modified and used for the removal of polymer nanoparticles from water. In order to enhance the interaction between the adsorbent surface and plastic particles in water, polyethyleneimine (PEI) was grafted onto the surface of the KT (PEI@KT). A series of techniques such as optical microscopy, FT-IR spectroscopy, scanning electron microscopy (SEM), elemental analysis, and thermal analysis were used to characterize KT and PEI@KT adsorbents. The adsorption of nanoparticles on the surface of the tubes was monitored using UV-Vis spectroscopy and electron microscopy. The modified fibers showed high removal rates (> 96 %) for negatively charged nanoparticles of polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), and polystyrene (PS) within 90 min. Additionally, the factors affecting the adsorption of nanoparticles, isotherm, and kinetic models were explored to investigate the adsorption mechanism of polymer nanoparticles (PNPs) on the PEI@KT surface. The collected adsorption data fit well with the Langmuir isotherm and pseudo-second-order kinetic models. The adsorption capacities of PEI@KT for the three types of polymer nanoparticles were high (> 240 mg/g). As a proof of concept, PEI@KT was used to remove plastic microparticles from a diluted solution of a commercial body scrub gel with excellent adsorption and removal efficiencies. Overall, the environmentally friendly PEI@KT adsorbent showed high adsorption efficiencies toward removing plastic particles from water.

Low-temperature sol–gel methods for the integration of crystalline metal oxide thin films in flexible electronics

The development of low-temperature sol–gel (solution) processes for the fabrication of crystalline metal oxide thin films has become a key objective in the emerging Flexible Electronics. To achieve this target, crystalline oxide films need to be deposited on flexible substrates, which have degradation temperatures below 350 °C (e.g., polymers or textile). This achievement would be a step towards improving the performance of the flexible device, making feasible applications now restrained (e.g. smart-skin, flexible-displays or solar-cells) and whose performance is associated to the functional properties of the crystalline oxide (e.g., ferroelectricity, pyroelectricity or piezoelectricity). However, this is a challenge because the crystallization of these oxides usually occurs at high temperatures, over 600 °C. This paper shows an overview to the solution strategies devised in our group for the low-temperature fabrication of crystalline metal oxide thin films, mostly ferroelectric perovskites (e.g., BiFeO3, PbTiO3 or Pb(Zr,Ti)O3). We have made use of UV-light as an alternative energy source to the thermal energy conventionally used to obtain the crystalline oxide. High photosensitive sol–gel solutions have been synthesized and the solution-deposited layers irradiated with UV-excimer lamps. A precise control of the photoreactions occurring during the irradiation of these layers has been carried out with the aim of advancing the formation of a high-densified, defect-free amorphous metal oxide film that easily can be converted into crystalline at temperatures compatible with the use of polymer substrates.Graphical An overview to the solution strategies devised in our group for the low-temperature fabrication of crystalline metal oxide thin films, mostly ferroelectric perovskites, is shown in this article. UV-light is used as an alternative energy source to the conventional thermal energy used to obtain crystalline oxide thin films. These solution strategies are based in the synthesis of high photosensitive sol–gel solutions and the irradiation of the solution-deposited layers with UV-excimer lamps under controlled irradiation atmospheres. A precise control of the photoreactions occurring in the system during the irradiation process has been carried out, with the aim of advancing the formation of high-densified, defect-free amorphous metal oxide films able to be converted into crystalline at temperatures compatible with the use of polymer substrates. This makes possible the integration of these advanced materials in the emerging Flexible Electronics.

Fabrication of crack-free oxidic thorium–cerium microspheres by an external gelation process

Thorium dioxide as an excellent matrix with stable properties is available for the direct incineration of plutonium, while (Th,Pu)O2 is a promising advanced fuel, which can be applied to a wide range of reactor types. In this study, cerium was used to simulate plutonium owing to their similar physicochemical properties. (Th1-xCex)O2 kernels were prepared by an external gelation process, which employs thorium and ceric ammonium nitrate as source materials, ammonium hydroxide as a neutralizing agent, polyvinyl alcohol as a thickening agent, and an ammonia gas ring for preliminary forming. The effect of the reaction temperature, reactant concentration, and pH on the feeding solution gelation properties was investigated. After the dispersive process, the aqueous (Th1-xCex)(OH)y·nH2O gel microspheres were washed and dried at 200 °C, calcinated and sintered. It was found that more than 99 % of the sintered microspheres maintained an excellent degree of sphericity and integrality when the parameters were properly controlled. It was found that the feeding solution preparation process was the most important and complex step to obtain uniform microspheres of good sphericity during the whole kernel fabrication process. The (Th1-xCex)O2 microspheres produced were characterized using thermogravimetric analysis, X-ray diffraction (XRD), scanning electron microscopy, and energy dispersive spectroscopy (EDS). The XRD analyses showed that all products appeared as a solid solution with a cubic fluorite structure when doped with cerium in the selective compositional range. The elemental scanning by EDS showed an excellent uniform distribution of thorium and cerium in the sintered microspheres.

Multiple-open-tubular column enabling transverse diffusion. Part 3: Simulation of solute dispersion along a real three dimensional-printed column with quadratic channels

Multiple-open-tubular columns enabling transverse diffusion (MOTTD) consist of straight and parallel flow-through channels separated by a mesoporous stationary phase. In Part 1, a stochastic model of band broadening along MOTTD columns accounting for longitudinal diffusion, trans-channel velocity bias, and mass transfer resistance in the stationary phase was derived to demonstrate the intrinsic advantage of MOTTD columns over classical particulate columns. In Part 2, the model was refined for the critical contribution of the channel-to-channel polydispersity and applied to address the best trade-off between analysis speed and performance. In this Part 3, a MOTTD column with a square array of quadratic channels is fabricated by 3D-printing (combining polymer stereolithography with photolithography using photomasks) to deliver unprecedently small apparent channel diameters of 117.6 ± 5.0 μm. The colors in the microscopy photographs of the actual 3D-printed channels are binarized to delimitate the mobile phase volume from the stationary phase volume. The same numerical simulations as those in Part 2 are then performed for two MOTTD columns (external porosity ϵe=31.7%, same apparent channel diameter 117.6 μm): one containing 16 virtual perfect quadratic channels and the other 16 real 3D-printed channels. The reduced velocities (or Peclet numbers) are varied over a wide range from 0.2 to 5000 and the zone retention factors were fixed at k1=1.04, 5, and 25.The results demonstrate that smoothing the edges of the targeted quadratic channels by the 3D-printed technique is advantageous in terms of solute dispersion. It outperforms the negative effect of the channel-to-channel polydispersity which is mitigated by transverse diffusion of the analyte in the stationary phase. For Peclet numbers larger than 50, the HETP of the 3D-printed MOTTD column is found 7%, 15%, and 16% smaller than that of the MOTTD column consisting of a square array of perfect quadratic channels. This confirms the known effect of channel geometry on solute dispersion in microfluidic systems. Flow channels in fabricated MOTTD columns are preferred to be circular so that the distribution of transverse diffusion lengths across the open channels remains as tight as possible. Finally, the general theory of nonuniform columns of Giddings reveals that the polydispersity of the cross-sectional area (RSD 8.4%) along a single 3D-printed channel has no negative impact on solute dispersion in MOTTD columns. Overall, MOTTD columns could become a serious alternative technology to conventional particulate columns. This implies a novel fabrication process that delivers circular channel diameters smaller than 10 μm, cross-sectional area polydispersity no larger than 25%, external porosities in a range from 15% (high speed separations) to 75% (high performance separations), and conventional mesoporous silica as the stationary phase. It adresses new synthesis routes based on either organic fibers or tubular micelle templating agents in suspension with silica gel solutions.

Study The Molarity Influence on the structural properties of titanium oxide (TiO2) Prepared with (Sol_Gel)

This report was conducted to study the molar effect on structural characteristics of Titanium dioxide TiO2 ,the deposition of films on glass substrates was done by using sol gel solution with Spin-Coting method (speed =3000 rpm) during 30 sec of the deposition where the solution have been prepared using Titanium hydroxyl Material Ti[O(CH2)3(CH3)]4 and C4H11NO2 as Fixative and Ethanol as a solvent. we have prepared different concentrations of solution (0.05, 0.10 , 0.15, 0.20, 0.30) M ,the films have been annealing with temperature (500 °C), we have investigated the Structural characteristics using (XRD,AFM and SEM) analyses. The (XRD) results have shown that the Anatase phase is the prevalent phase when the concentrations (0.05 and 0.10)M and after increase the concentration start changes gradually from Anatase phase to Rutile phase when the concentration (0.2)M. The SEM analyses have approved that the film has good topography. The granules had a rhombus form then its shape became cluster with the increasing of concentration . The (AFM) have shown that the membranes had nano- thickness,and they are soft with good coating

Fe3O4@SiO2 Core–Shell Nanoparticles: Synthesis, Characterization Prepared by Green Method for Iraqi Aloe Vera Extract

In this work, a green approach was used to create Fe3O4 nanoparticles. After that, ferrous chloride tetrahydrate and ferric chloride hexahydrate solutions were mixed with various quantities of Iraqi Aloe Vera gel and sodium hydroxide solution to achieve pH(8). Then, in the scale synthesis of silica-coated iron oxide NPs utilizing nontoxic and low-cost materials, tetraethyl orthosilicate (TEOS) was employed as a precursor to silica. (UV–Vis), FT-IR, XRD, AFM, EDS, TEM, Zeta Potential, VSM, FESEM and VSM were used to characterize the as-prepared silica-coated (Fe3O4@SiO2 CSNPs) and Fe3O4 NPs. UV–Vis exhibits an absorption band in the ultraviolet region at approximately 300 nm in Fe3O4NPs and 310[Formula: see text]nm in Fe3O4@SiO2 CSNPs, this means red shift occurs successively. Results of (XRD) and (EDS) analyses demonstrate that magnetite nanoparticles were effectively coated using this easy process. FESEM and TEM measurements demonstrate that the particle size of iron oxide nanoparticles and iron oxide NPs CSNPs increases before and after coating with spherical particles in form. AFM evaluates surface tension and surface energy. It is found that the surface roughness of magnetite nanoparticles NPs is 49.31[Formula: see text]nm and root mean square (RMS) is 319.8[Formula: see text]nm, whereas in core–shell it is 25.45[Formula: see text]nm and 166.7[Formula: see text]nm, respectively, it was raised in the case of the core–shell. This means decrease in particle size. Magnetic properties from (VSM) test demonstrate that the magnetization of the as-synthesized TEOS-coated magnetite NPs is lower than that of freshly created bare magnetite NPs, demonstrating the formation of Fe3O4@SiO2 CSNPs. The stability was around [Formula: see text][Formula: see text]mV, and the addition of magnetic and optical features improved their biocompatibility. The antibacterial activity of Fe3O4 NPs and Fe3O4@SiO2 CSNPs was investigated using the agar well diffusion method agains t Staphylococcus aureus Gram-positive and Escherichia coli Gram-negative bacteria, which exhibited a wide spectrum of antibacterial potency inhibiting the growth of both Gram-negative (8[Formula: see text]mm, 10[Formula: see text]mm) and Gram-positive (7[Formula: see text]mm, 12[Formula: see text]mm), respectively.

Instantaneous gelation and non-existence of weak solutions for the Oort–Hulst–Safronov coagulation model

The possible occurrence of instantaneous gelation to the Oort–Hulst–Safronov (OHS) coagulation equation is investigated for a certain class of unbounded coagulation kernels. The existence of instantaneous gelation is confirmed by showing the non-existence of mass-conserving weak solutions. Finally, it is shown that for such kernels, there is no weak solution to the OHS coagulation equation at any time interval.

Preparation and rheology of titanium dioxide nanoparticles loaded κ‐carrageenan hydrogel beads strengthened by mixed salts for multipollutant water remediation

AbstractHydrogel beads are emerging as alternate adsorbent material for the batch or continuous column treatment of dye wastewater. Polysaccharide‐based gel beads are preferred for their uniform shape and size, large specific surface area, and easy separation by filtration and subsequent reuse. In this work, we prepare and rheologically characterize UV‐active κ‐carrageenan/TiO2 beads for the adsorption and degradation of dyes. The 3–4 mm sized nanocomposite beads are formed by the extrusion of κ‐carrageenan/TiO2 gel solution in salt solutions. The maximum increase in modulus was observed with the addition of 1% w/v TiO2 to κ‐carrageenan and subsequent crosslinking with mixed salt of KCl and CaCl2. κ‐carrageenan/TiO2 beads crosslinked by mixed salt of KCl and CaCl2 have higher adsorption capacity, as compared to beads crosslinked with single salt of KCl. The kinetic study indicated the chemisorption of Methylene Blue on the bead surface. κ‐carrageenan/TiO2 beads showed higher degradation for Methylene Blue and Nile Blue A than Rhodamine B in 5 and 50 ppm each multicomponent dye systems under UV irradiation. The κ‐carrageenan/TiO2 beads could form a porous column for the selective adsorption of positively charged dyes from a multicomponent dye system.

TLC–Densitometric Analysis of Selected 5-Nitroimidazoles

Metronidazole, ornidazole, tinidazole, and secnidazole are 5-nitroimidazoles. The purpose of this work was to propose a new economical TLC–densitometric method to evaluate the chemical stability of metronidazole, secnidazole, ornidazole, and tinidazole under stress conditions. A forced degradation study was performed on silica gel and aqueous solutions at various pH values; the metronidazole, secnidazole, ornidazole, and tinidazole solutions were prepared in saline and in hydrogen peroxide, respectively. The samples of the 5-nitroimidazoles were heated. TLC analyses were performed on silica gel 60F254 using chloroform–methanol (9:1, v/v) as the mobile phase. As the TLC–densitometric method can effectively separate the metronidazole, secnidazole, ornidazole, and tinidazole from their degradation products which formed as a result of the stress studies, it is considered to can be a good alternative and important tool in the routine quality control and stability testing of metronidazole, secnidazole, ornidazole, and tinidazole in pharmaceutical formulations. The results indicate that the proposed TLC–densitometric method is cost-effective, rapid, specific, accurate, and precise; the TLC–densitometric method also realizes the criterion of the linearity. A major advantage of the proposed method is its low cost and ability to analyze the 5-nitroimidazole which was investigated and all its degradation products simultaneously.

The Impact of Chlorhexidine Mucoadhesive Gel in the Prevention of Ventilator-Associated Pneumonia: A Randomized Clinical Trial.

Ventilator-associated pneumonia is the common cause of morbidity and mortality in the intensive care unit. Due to the antimicrobial effect of chlorhexidine, and the long-lasting result of mucoadhesive drugs, this study aimed to determine the effect of chlorhexidine mucoadhesive gel on the prevention of ventilator-associated pneumonia in critical patients. In this clinical trial, 64 ventilated patients were selected and randomly allocated into two groups. The first group received 0.2% chlorhexidine mucoadhesive gel and the second group received 0.2% chlorhexidine solution as a mouthwash. Every three days, the incidence of ventilator-associated pneumonia was evaluated by the clinical score of pulmonary infection. The data were analyzed by SPSS statistical software version 20. There was no statistically significant difference in demographic characteristics between the two groups. In the control group, 25% of the patients had ventilator-associated pneumonia, while it was only 15.6% in the intervention group; however, the incidence of ventilator-associated pneumonia revealed no significant difference between the two groups (HR ratio, 0.86; 95% confidence interval, 0.49 to 1.83 p =0.356).In addition, there was no statistically significant difference between the number of days connected to the ventilator (p =0.854), the number of days hospitalized in the intensive care unit (p =0.423), and the death rate (p =0.634) between the two groups. Although no significant statistical difference was detected between chlorhexidine mucoadhesive gel and chlorhexidine solution in the prevention of ventilator-associated pneumonia, the incidence of pneumonia in the mucoadhesive gel group was clinically less than in the control group. It is better to repeat the study with a larger statistical population.

Effects of pH and incubation temperature on properties of konjac glucomannan and zein composites with or without freeze-thaw treatment

This work investigated the effect of pH and incubation temperature on the morphology and properties of konjac glucomannan (KGM)-zein composites with or without freeze-thaw treatment. When the incubation temperature was 90 °C, the composites prepared in the pH range of 10.5–11.5 were concentrated polymer solutions, while the composites prepared in the pH range of 12.0–13.0 were gels. The pH of 12.5 was found to form the composites with the most dense microstructure, the highest storage modulus and crystallinity, and the greatest ability to resist plastic deformation during compression. The composites tended to form gels with the increase of incubation temperature from 40 °C to 90 °C at pH = 12.5. The temperature of 90 °C was found to form the composites with the most dense microstructure, the greatest ability to resist plastic deformation during compression, and the highest crystallinity and frequency stability. The composite prepared at an incubation temperature of 70 °C and a pH = 12.5 had similar microstructure, rheological properties, and texture properties to that prepared at an incubation temperature of 80 °C and a pH = 12.0. The freeze-thaw treatment caused a slight increase in storage modulus (G′) and crystallinity when the composites were concentrated polymer solutions. When the composites were gels, the freeze-thaw treatment caused a rough and inhomogeneous microstructure, increased the G′ and the ability to resist plastic deformation during compression, decreased the springiness, and altered the internal water mobility. pH and incubation temperature play important roles in the morphology and properties of KGM-zein composites. • The composites were concentrated polymer solutions prepared at 80 °C and pH ≤ 11.5. • The composites were gels prepared at 40 °C–80 °C and pH = 12.5. • 70 °C and pH = 12.5 endowed the composite with similar properties to 80 °C and pH = 12.0. • Freeze-thaw treatment had different effects on gel and concentrated polymer solution.