Gel Technology Research Articles

Reactive Hot Pressing of HfB2–SiC–Ta4HfC5 Ultra-High Temperature Ceramics

Highly disperse and reactive (HfB2–SiC)@(Ta2O5–HfO2–C) composite powders were manufactured by sol–gel technology where Ta2O5–HfO2–C amorphous components were nanostructured and distributed in each other as uniformly as possible. The reactive sintering of the prepared composite powders at a relatively low temperature (1800°С) with an exposure time of 30 min and the pressure 30 MPa yielded (HfB2–30 vol % SiC)–xTa4HfC5 ultra-high temperature ceramics (UHTCs), where x = 5, 10, and 15 vol %, with a relative density of 75–78%. X-ray powder diffraction proved the complete conversion of tantalum and hafnium oxides to complex carbide Ta4HfC5. The average grain size as determined by scanning electron microscopy did not exceed 2–3 µm in HfB2 and 30–60 nm for the Ta4HfC5 phase. Thermal analysis in flowing air showed that, in the temperature range 20–1400°С, the increasing percentage of tantalum–hafnium carbide (the least oxidation resistant phase) leads to a systematic increase in oxidation-induced weight gain; however, a tendency to saturation is observed. The microstructural specifics of the oxidized surface are noticed depending on the composition of HfB2–SiC–Ta4HfC5 ceramics.

Impact of High Pressures during the Compaction of Zirconia Nanopowder on Material Structure Formation

The influence of compaction pressure during semidry compaction in a steel mold of zirconia powder partially stabilized by yttria on the phase composition and microstructure of formed compacts, as well as samples sintered at 1400°C for 2 h, is investigated. An aqueous solution of polyvinyl alcohol is selected as a temporary manufacturing binder. The yttria content in the powder synthesized according to the sol–gel technology (the deposition by an aqueous-ammonia solution from aqueous ethanol solutions of corresponding reagents with the agar-agar additive) is 3.2 mol % according to the X-ray fluorescent analysis data. The results of studying the compacts and sintered samples by Raman spectroscopy, optical microscopy, and atomic force microscopy are presented. It is established that an increase in their density is not monotonic. There is the critical range of compaction pressures P = 400–450 MPa, in which the porosity, pore shape and sizes, microstructure, and phase composition of the material vary abruptly. A monoclinic phase, the content of which varies upon varying P, is fixed in compacted samples along with tetragonal zirconia. Material grain grinding is associated with the destruction of agglomerates and actively occurs in range P = 350–550 MPa. A similar effect when studying the compaction process of nanopowders of zirconia is also noted by other researchers, who assumed that the response of the nanopowder system on the pressure effect is associated with the influence on the aqueous component (the temporary manufacturing binder in this case) and is caused by the transition of one form of water into another one at 10–25°C and a pressure of 400–700 MPa.

Testing of preformed particles polymer gel technology on core filtration models to limit water inflows

In order to reduce watering of wells and equalize their injectivity profiles, the prospects of introducing PPG technology in Russian fields are considered, in which preformed particles polymer gel are pumped into the injection well. These particles, being a supersorbent based on polyacrylamide, absorb water, become elastic, which allows them to shrink and tear in narrow filtration channels. When the polymer is filtered along permeable layers saturated with water, polymer particles accumulate in waterlogged intervals and thus they form a polymer plug, which redistributes the filtration flows and increases the coverage of the formation by the process of oil displacement.More than 4000 downhole operations have been carried out in the fields of China and the USA using PPG technology by now. In domestic fields in Western Siberia, there is limited experience in applying a similar technology in high-temperature formations with low mineralization of formation water. Due to the absence of hydrolytic processes in polyacrylamide, well-known domestic compositions are not applicable due to the low absorption capacity in the conditions of low-temperature deposits with increased mineralization of formation water.The authors synthesized a polymer based on polyacrylamide by block polymerization, which allows to obtain a high absorption capacity, including for low-temperature formations with high mineralization of formation water, which is typical for Perm Territory fields.Filtration experiments were carried out on core models with the composition developed by the authors, this composition focused on low formation temperatures and high mineralization of formation water. As a result of the experiments, it was found that the swollen particles of the gel are able to pass into fractures with a diameter less than their own size at least 20 times. With a significant increase in the viscosity of the dispersion medium, the stability of the suspension increases. Particles of polymer gel have the necessary strength for injection in the field conditions. The fracture permeability during polymer injection decreases by several times and becomes comparable with the permeability of pore collectors.

An exploration of the advantages of automated titration testing: low inter-instrument variability and equivalent accuracy for ABO and non-ABO antibody titres relative to tube testing.

Obtaining IgM and IgG titres is important in numerous clinical situations, including solid-organ transplant, obstetrics, and for testing of out-of-group plasma-containing components. Tube method is the most prevalent testing modality, though it is both labour-intensive and known for intra- and inter-laboratory variability. The utility of automated gel testing as a method to improve both inter- and intra-laboratory reproducibility is unknown. Two academic centres participated in a study evaluating automated gel titreing. Group O plasma samples were used to measure titres of antibodies against ABO (IgM) with buffered gel cards and 4 minor and minor red-blood-cell antigens (IgG) anti-IgG gel cards. Multiple ORTHO VISION automated analyzers were used to assess inter-instrument variation. A subset of ABO (IgM) samples were compared between laboratories to evaluate inter-laboratory variability. Multiple samples were titred by tube and by automated gel technology to determine similarity of results. Testing demonstrated no significant difference between analysers or between sites when performing automated titrations (P≥0·99). Non-ABO IgG titres were evaluated and demonstrated little inter-instrument variability. The IgM anti-A and -B titres obtained by automated gel testing were neither consistently higher nor lower than tube titres. Greater than 90% of titre values were within one dilution. Based on this study, our data suggest that titreing by automated gel testing is both highly reproducible (IgM and IgG) and does not differ significantly from manual tube testing results of direct agglutination (IgM).

Research on the development of dental gel technology with metronidazole benzoate and hyaluronic acid

Aim. Development of technology of dental gel with combined composition, establishment of optimal technological parameters for the introduction of active and auxiliary substances.Methods. After production of experimental gel, we determined homogeneity for the samples with the method of SPhU 1.1, section 511. The particle size of the suspension was studied using a XY-B2TLED microscope under polarized light according to SPhU 2.9.37. The quantitative determination of metronidazole benzoate and the accompanying impurities A, B, C, miramistin, sodium hyaluronate was performed by liquid chromatography, according to SPhU section 2.2.29, section 2.2.46.Results. According to the results of chemical and microscopic studies, the optimal method of introducing metronidazole benzoate into the gel base is the suspension method. To ensure the best distribution of metronidazole benzoate, a micronized substance was used and the technological parameters of pre-homogenization of metronidazole benzoate in propylene glycol at 20-25 °C were determined. Microphotographs of the gel samples showed that homogenization of metronidazole benzoate with propylene glycol at a speed of 3000 to 4000 rpm provides a homogeneous translucent gel of white colour. Selected methods of dissolution and technological parameters allow to obtain a stable gel without degradation products of active substances.Conclusions. The optimal way of introducing into the gel base the combination of active substances: metronidazole benzoate, myramistine, hyaluronate sodium is substantiated. The rational technology of production of the combined dental gel is developed. Critical stages and parameters of technological process are defined, criteria of their acceptability are established

Obtaining of NiO Nanosheets by a Combination of Sol–Gel Technology and Hydrothermal Treatment Using Nickel Acetylacetonate as a Precursor

Nickel oxide nanosheets were manufactured using sol–gel technology and hydrothermal treatment. The effect of hydrothermal treatment on the hierarchical organization character of the thus-manufactured oxide powder was shown. The microstructural parameters of the powder were studied by transmission (TEM) and scanning (SEM) electron microscopy; The homogeneity of the powder and the absence of impurities of another chemical composition were verified by energy dispersive elemental microanalysis (EDX).

Carbon Monoxide Hydrogenation over Gd(Fe/Mn)O3 Perovskite-Type Catalysts

Catalytic properties of GdFeO3 and GdMnO3 perovskite-type oxides in CO hydrogenation processes is conducted. Complex oxides Gd(Fe/Mn)O3 are synthesized by the sol–gel technology and characterized by X-ray diffraction, temperature-programmed reduction, and scanning electron microscopy. It is found that the iron-containing catalyst has fairly high catalytic characteristics; therefore, it provides lower temperatures of carbon monoxide hydrogenation. The presence of manganese in the catalyst leads to an increase in light olefin selectivity compared with the sample containing iron at the B-site. It is assumed that gadolinium cations are responsible for dissociative chemisorption, while iron and manganese cations are responsible for the formation of atomic hydrogen. The two catalysts exhibit resistance to carbon deposition.

Abstract DP-008: SILICA GEL ENCAPSULATION AS A POTENTIAL TOOL TO IDENTIFY DORMANT AND DRUG-RESISTANT CELL POPULATIONS IN OVARIAN CANCER

Abstract Despite advances in standard of care treatment, a significant number of ovarian cancer patients will exhibit disease recurrence, either due to the presence of chemoresistant cells or the reawakening of dormant tumor cells. Currently there are no methods to predict which patients are likely to recur, and the mechanisms that allow a unique subpopulation of cancer cells to enter dormancy and survive chemotherapy remain unclear. Since chemotherapy is more effective at destroying highly proliferative cells, it is theorized that tumor cells capable of entering a dormant state are also the same population able to evade initial treatment and ultimately engender chemoresistance. A silica gel encapsulation platform that uses physical confinement to inhibit proliferation has previously demonstrated the ability to distinguish between dormancy-capable and dormancy-incapable breast cancer cell lines. In this work, we sought to apply this platform to an ovarian cancer cell line and determine if it could be used to select for the dormancy-capable subset of cells and to detect differences upon enrichment of dormant or chemoresistant cell populations. Upon encapsulation in silica gels, surviving OVCAR-3 cells demonstrated hallmarks of dormancy, including reduction in Ki67 expression, modulation of key cell cycle regulatory genes and dormancy-associated signaling pathways, and ability to resume proliferation when the stress of physical confinement was removed. Moreover, enrichment of the dormant subpopulation using hypoxia treatment or serum starvation prior to silica gel encapsulation resulted in enhanced survival in gels relative to cells grown in standard culture conditions. These results suggest that silica gel encapsulation may be used as a simple method to isolate dormancy-capable cells for further applications such as gene or protein expression analysis and drug screening. Similarly, cells already in a dormant state demonstrated lower susceptibility to cisplatin drug treatment relative to actively proliferating cells, further supporting the idea that dormant cancer cells are less susceptible to chemotherapy and that chemoresistance may stem from a subpopulation of dormant cancer cells. After extraction from silica gels and subsequent return to a proliferative state, cells surviving prolonged encapsulation also demonstrated enhanced survival after cisplatin treatment relative to control populations. This suggests that the dormancy-capable cells selected for within silica gels are indeed more chemoresistant, even when no longer dormant, and that the ability to enter dormancy and chemoresistance in ovarian cancer are likely somehow connected. Lastly, when the drug-resistant phenotype was selected for through cisplatin drug treatment prior to encapsulation, a significant difference in viability was observed upon encapsulation between cisplatin-treated and untreated cells. Overall, these results indicate that the silica gel technology and the behavior of ovarian cancer cells after encapsulation may be an indicator of cells inherently capable of entering dormancy and less susceptible to platinum-based chemotherapies. In future applications, silica gel encapsulation of patient ovarian cancer cells could potentially be used as a predictive clinical tool to identify patients at risk of early recurrence or as a facile in vitro platform to investigate mechanistic links between dormancy, chemoresistance, and recurrence. Citation Format: Tiffany Lam, Hak Rae Lee, Melissa A. Geller, Alptekin Aksan, Samira Azarin. SILICA GEL ENCAPSULATION AS A POTENTIAL TOOL TO IDENTIFY DORMANT AND DRUG-RESISTANT CELL POPULATIONS IN OVARIAN CANCER [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr DP-008.

Investigation of Gas-Sensitive Properties of Thin-Film Thermovoltaic Sensor Elements Based on Zinc Oxide

Systematic research on a new type of gas sensor devices based on the thermovoltaic effect in zinc oxide, inhomogeneously doped with impurities of variable valence, is presented in the article. The ZnO–ZnO–Me two-layer sandwich structure, in which the thermovoltaic effect is observed, is synthesized using sol–gel technology from sols by dissolving the inorganic zinc salt in alcohol and adding a surfactant, followed by the mixing and maturation of the sol. The lower layer of the nanostructure is formed from pure zinc oxide by immersing the substrate at ⅔ length in sol and drying. The upper layer of zinc oxide doped with copper or iron is formed by two or three immersions of the other end of the substrate by ⅔ length, followed by drying and annealing. It has been established that, based on the developed sensor device, it is possible to obtain an increased response to gas-analyzers (ethanol being an example).

Coprecipitation of Au clusters and alumina sol in supercritical CO2—the facile way to stabilize gold nanoparticles within oxide matrix

A novel method for the synthesis of catalytically active composites based on gold clusters incorporated into an alumina matrix was proposed. The method combines sol–gel and supercritical fluid technologies. The composites were synthesized by precipitating of gold clusters and alumina sol mixture in the supercritical antisolvent (SAS) carbon dioxide medium. Gold clusters were synthesized in the colloidal solution of alumina sol in situ (one-pot synthesis) via controlled reduction of AuIII using PPh3 as a stabilizer for the first time. It was shown that this method allows us to stabilize gold clusters with sizes less than 2 nm in the alumina matrix with a developed specific surface area (SBET = 441 m2/g) and a narrow pore size distribution. The obtained composite does not contain stabilizer, which may poison the catalyst. The developed approach makes possible to synthesize catalytically active composites with a certain amount of gold cluster and oxide matrix of different nature.

Customized lip enhancement for clinical different lip features: An observational study.

The request for lip improvement treatments with injectable hyaluronic acid (HA) is increasing. However, as the patient's needs can be extremely different, it is unconceivable to use the same technique/product for clinical different lips to grant customized results. To provide a specific treatment approach for clinically different lips based on the Author's clinical experience. Patients belonged to four clinical groups: young lips requiring volume enhancement or a reshaping intervention, and senescent lips requiring rejuvenation or a rebuild intervention. At first visit T0, subjects underwent a pretreatment evaluation and the investigator performed an individual treatment based upon patient's esthetic goals and lip's baseline features. Lip fullness was assessed by the investigator using a Medicis Lip Fullness Scale (MLFS) at first visit (T0) and at 2weeks (T1). Subjects and investigator answered to the Global Aesthetic Improvement Scale (GAIS) at 2weeks T1 and at 12weeks (T2). A photographic evaluation was undertaken at T0 and T2. Only, in the two groups requiring volumization there was 1 grade of improvement in the MLFS (young lips-volume and senescent lips-rebuild). Nonetheless, the performed combination of techniques/products was overall very satisfactory: 80% of the subjects reported a much improved/very much improved outcome in the GAIS, and the same was reported by the investigator in 90% of the subjects. A weak positive correlation was found between MLFS responses and subject's GAIS at T1 in all groups. This customized treatment approach, consisting in choosing the right gel technology injected in minimum quantities with the right technique, ensures a harmonic result avoiding aberrations and standardizations.

A retrospective study of the added value of parallel titers compared with serial titers.

Prenatal antibody titers for alloimmunized patients are subject to multiple sources of variation. A parallel titer on the previous sample at the same time as the current sample is recommended. The purpose of this study was to determine the added value of parallel titers. This is a retrospective study of samples from consecutive prenatal patients with at least two prenatal antibody titers performed in the same pregnancy at a single institution between October 2010 and March 2017. Prenatal titers were performed using gel technology. Data were collected to determine the sensitivity and specificity of a clinically significant increase (twofold or greater) in serial titers compared with the gold standard of using parallel titers. There were 155 serial prenatal titers performed in 59 alloimmunized pregnant women. Nineteen samples (12%) had a serial titer increase of twofold or greater with eight false positive samples (increase less than twofold when using parallel titers). Thirty-six samples (23%) had a serial titer increase of onefold with two false negative samples (increase of twofold or greater using parallel titers). One hundred samples (65%) had no increase (or a decrease) in serial titer with none having an increase of twofold or greater using parallel titers. The sensitivity of a twofold or greater increase in serial titers was 84.6% (95% CI 55-98%) and the specificity was 94.4% (95% CI 89-98%) when compared with parallel titers. This study questions the value of parallel titers on every prenatal titer performed. When no increase in serial titers was observed, parallel titers added no new information.

Outcomes Utilizing Inspira Implants in Primary Aesthetic and Reconstructive Surgery

The evolution of silicone implants has included advances in both gel and shell technology to improve the clinical outcomes of the implants. The newest generation of implants includes implants with thick, strong shells and highly cohesive gel fill. These advancements allow for better maintenance of implant form and shape over time and improved implant safety. The Natrelle Inspira product line offers 3 different levels of gel cohesivity in a range of profiles to provide a wide variety of options for use in both breast augmentation and postmastectomy breast reconstruction. This article will review the use of Inspira implants in primary aesthetic and reconstructive breast surgery.

A pilot study of soft gel technology: a new vaginal device to improve the symptomatology of vulvovaginal atrophy in post-partum, menopause and in patients with recurrent vulvovaginitis.

This is a pilot study to evaluate the effectiveness of the treatment with Vaginal Soft gels technology in the improvement of common signs and symptoms in postmenopausal, postpartum and with recurrent vulvovaginitis patients. These conditions may cause the onset of Vulvovaginal Atrophy (VVA) with effects on sexual activity, self-confidence and daily activities. The main symptoms are itching, irritation and dryness. Many therapies have been evaluated and almost all those without hormonal component have shown poor results. Women diagnosed with severe VVA from January to September 2018 were recruited. The study groups were composed of 25 postmenopausal women, 30 post-partum women and 30 women with recurrent vulvovaginitis. For each group, patients were randomized 1:1 among those who carried out the experimental treatment and those that did not perform it. The efficacy of treatment was evaluated with a clinical visit in which Vaginal Health Index (VHI) was estimated. The symptomatology was determined through the questionnaire Female Sexual Function Index (FSFI). A significant improvement has been shown with regard to the sexual function (orgasm, lubrification, pain) in patients who performed the treatment. A significant increase in VHI has been evaluated in postmenopausal patients (4 months p=0.054, 6 months p=0.005) and in recurrent vulvovaginitis but not in post-partum patients (4 months p=0.681, 6 months p=0.109). An improvement of lubrication, satisfaction, orgasm, pain, as well as dyspareunia, was observed in the three study groups. In this pilot study the treatment with soft gels seems to be effective in improving sexual health and atrophy being a treatment available for all types of patients thanks to the absence of systemic and local side effects. It is an excellent alternative especially for patients who cannot use hormones. These findings must be confirmed by larger and randomized further studies.

Experimental Investigations on Foaming Device Used for Coal Spontaneous Combustion Prevention

ABSTRACT Foamed gel is widely used for coal spontaneous combustion prevention in coal mines, and foaming device is the key part for foamed gel preparation. The device is mainly composed of reducing pipeline, diffuser, and convection adder, mixing plate, of which the inlet and outlet radius of reducing pipeline are 30 mm and 7.5 mm, the distance between diffuser and the outlet of the reducing pipeline is 20 mm. Further, foamed gel preparation system based on foaming device is built in lab, and the optimum preparation procedures and parameters are obtained with water flow volume 4 m3/h, air pressure 0.4 MPa. The final foam multiple is 15 times, gelation time is 100–500 s. Field application on coal self-ignition prevention showed that this new foaming device could produce a large amount of foamed gel to meet the application. Therefore, it is believed that this study laid an important foundation for the widespread application of foamed gel technology for coal spontaneous combustion control in coal mines.

Utilizing Crude Waste Glycerol in the Biorefinery: Glycerol Gels for in Situ Substrate Delivery to Whole Cell Biocatalysts

Sol–gel methods were used to facilitate the in situ controlled delivery of glycerol as a substrate for whole cell biocatalysis. The entrapment of the polyol within a silica gel matrix enabled the utilization of crude and moderately toxic bioderived substrates that could not be used in fed-batch mode. Different grades of glycerol were incorporated in gels and fed to C. butyricum for 1,3-propanediol production and to E. coli for recombinant protein production. Of particular note was the successful use of crude glycerol gels with E. coli. By virtue of gel immobilization, previously toxic crude glycerol samples were rendered active, and the use of gel technologies was therefore shown to expand the range of biomass that can be utilized in whole cell biocatalytic processes. Specific matching of the acid used in the gel synthesis with the fermentation medium further supported cell growth.

Preparation and Application of Needle Extraction Device Packed with Sol–gel-Derived Perhydroxy Cucurbit[6]uril Coating Fiber

A novel needle extraction device packed with heat-resistant fibers coated with perhydroxy cucurbit[6]uril by sol–gel technology was first developed for the analysis of polycyclic aromatic hydrocarbons in actual water samples. Its performance was tested via purge and trap microextraction coupled with gas chromatography. The strong adsorption affinity between polycyclic aromatic hydrocarbons and (OH)12Q[6] was attributed to C–H···π interactions and π–π interactions. The parameters of the extraction device, such as extraction volume, extraction temperature, desorption time, ionic strength, and fiber number, were optimized. Under optimized conditions, the as-prepared extraction device showed good linearity within 0.5–1,500 µg L−1 with low detection limits (0.03–0.2 µg L−1). Moreover, the durability of the needle extraction device was excellent and can be used for 60 cycles. Furthermore, the loss rates of the coating fiber were less than 10% after storage for 3 days at room temperature, and the RSD was less than 6.4%.

Phase formation and luminescent properties of Сa12Al14O33:Eu, Nd prepared by sol–gel method

Сalcium aluminate Ca12Al14O33 and phosphors based on it were obtained using sol–gel technology. Complex studies were used to identify the dynamics of phase and structural transformations in the synthesis of Ca12Al14O33. The main stages of the calcium aluminate formation were determined using thermal analysis, IR spectroscopy and X-ray phase analysis. Solid-phase interaction in the formation of Ca12Al14O33 includes the steps of obtaining calcium carbonate and amorphous alumina (800 °C), aluminates of composition Ca3Al2O6 and CaAl2O4 (900–1000 °C), and Ca5Al6O14 and Ca4Al6O13 (1000–1100 °C). Ca12Al14O33 begins to form at 1100 °C. The graphic image of the structure was constructed according to the obtained atomic coordinates using the ReX Powder diffraction program. Luminescent properties of the phosphors of the composition Ca12−(0.05+x)Al14O33:NdxEu0.05 (x = 0.025–0.1) were investigated. It was determined that the highest intensity of luminescence is achieved at x = 0.05. With a further increase in the content of neodyum, there was a concentration quenching of the luminescence.

Preparation and characterization of cocoa butter and whey protein isolate based emulgels for pharmaceutical and probiotics delivery applications

Emulsion gel (emulgel) technology has proven to be one of the viable options for designing delivery systems for drugs and probiotics. Such formulations are quite stable as compared to emulsions but possess all the advantages of the biphasic formulations. In our research study, we have developed a series of emulgels using cocoa butter as the fat phase and whey protein isolate (WPI) solution as the aqueous phase for designing efficient delivery systems. The prepared emulgel was characterized by microscopy, XRD, FTIR, mechanical, and electrical analyses. The aqueous phase was present as globular structures which were dispersed uniformly throughout the fat matrix. There was a change in the crystal habit due to hydrogen bonding which ultimately resulted in the alteration in the crystallinity index, viscoelastic and thermal properties of the formulations. An increase in the WPI solution consequently resulted in the decrease in the impedance of the emulgels. The WPI containing emulgels showed better drug diffusion and probiotics viability as compared to the cocoa butter only formulation (control).

Photocurrent Hysteresis of Sol–Gel Derived Strontium Titanate Films on Silicon

SrTiO3 and SrTiO3:Nd films of 110[Formula: see text]nm and 210[Formula: see text]nm thickness were fabricated using the sol–gel technology on silicon. Their current–voltage characteristics were investigated with and without illumination. The film structures are photosensitive and exhibit the hysteresis on the forward and reverse bias with loop broadening at the reverse part.