Gel Fill Research Articles

Mechanical and micro-mechanical investigations of nano-SiO2 and polypropylene fiber reinforced cement soil in marine environments

The degradation of cement-stabilized soil foundations in coastal environments is primarily caused by the corrosive effects of chloride and sulfate ions. While Nano-SiO2 enhances the mechanical properties of cemented soil, it may also increase brittleness, affecting safety and cost-effectiveness. Polypropylene fibers improve ductility by inhibiting crack propagation but contribute minimally to strength enhancement. To optimize performance, this study employed 3.6% Nano-SiO2 and 0.8% polypropylene fibers. Unconfined compressive strength (UCS) tests indicate that with increasing curing time, erosion from Cl− and SO 4 2 − significantly increases the brittleness of Nano-modified cemented soil, with compressive strength initially rising and then declining. The incorporation of polypropylene fibers further enhances both compressive strength and deformation modulus. At 60 days of curing, the composite cemented soil exhibits strength improvements greater than the sum of the individual gains in various environments, with compressive strength increases of 248.9, 159.9, and 102.9% in freshwater, chloride, and sulfate conditions, respectively. Scanning electron microscopy and X-ray diffraction analyses indicate that excessive expansion products from Cl− and SO 4 2 − reduce Nano-SiO2’s effectiveness. The C-S-H gel fills the indentations on the fiber surface and tightly envelops it, while Nano-SiO2 further enhances the mechanical interlocking between the fibers and the matrix, thereby improving durability in marine.

Study on modification of natural hydraulic lime historical building repair mortar

Qingdao boasts a wealth of historical buildings, yet they have sustained varying degrees of damage due to environmental erosion over decades. Traditional cement-based repair materials can exacerbate the damage to these structures and often fall short of the stringent requirements for historical building restoration projects. Natural Hydraulic Lime (NHL) offers excellent compatibility and breathability, making it suitable for restorative work on historical buildings. However, its low early strength and durability pose limitations in Qingdao's complex environment. Consequently, this study investigates the enhancement of NHL mortar using Ground Granulated Blast Furnace Slag (GGBFS/BFS) powder. Nine mix formulations were developed to investigate the impact of varying BFS contents on the physical properties and microstructure of the repair mortar. The results indicate that, compared to the reference sample, the modified mortar exhibits reduced water requirement for normal consistency, shorter setting time, lower water absorption, and decreased shrinkage. Regarding mechanical properties, the incorporation of BFS significantly enhances the mechanical strength of the repair mortar. When the proportion of BFS is 60 %, the flexural and compressive strength of the mortar samples increase by 304 % and 611 % at 28 days, respectively. Upon incorporating BFS, a pozzolanic reaction occurs in the alkaline environment, leading to the formation of calcium silicate hydrate (C-S-H) gel. This gel fills the pores within the mortar, enhancing the densification of the system, which in turn improves the mechanical properties and microstructure of the repair mortar. SEM analysis corroborates these findings. XRD analysis confirms that BFS does not introduce harmful substances.

Microstructure tests, flow, and mechanical behavior of polymerized cement mortar

The influence of two types of polymeric admixture on the stress–strain (σ-ε) behavior of cement mortar is discussed in this article. The characteristics of cement mortars modified with two types of polymeric admixtures containing 0.20 percent (% wt.) were investigated. For early age (1 day) and 28-day curing periods, the σ-ε behavior of modified cement mortar with polymeric admixtures was investigated. Depending on the polymeric structure and content, adding polymeric admixture reduced the water/cement ratio (w/c) by 14.5 to 25.5 %. When 0.20 % of polymeric admixture was added to cement mortar, the compression strength improved by 72 % to 153 %. The cement mortar samples became brittle as the polymeric admixtures content increased. The amorphous gel fills the spaces between cement particles and sand particles, decreasing voids and porosity and improving the density of the cement mortar. To forecast the connection of the modified cement mortar with polymer, the nonlinear Vipulanandan p-q equation was used, and it was compared to the Farazdaghi- Harris-YD and Sinusoidal models. The compressive stress–strain models were evaluated using statistical methods, and nonlinear approaches were utilized to predict compressive strength as a function of water/cement ratio, curing age, and polymer quantity. The less complicated model, the Vipulanandan p-q model, already has a smaller sum of squares than the other two models. Therefore, the Vipulanandan p-q model is the best one.

Effect of sodium silicate concentration on the physico-chemical properties of dual-setting bone-like apatite cements

Calcium phosphate cements (CPCs) with their biocompatibility, osteoconductivity and injectability plays an important role in bone defects treatment. Dual-setting cement is a promising approach to improve the physicochemical and biological properties of CPCs in which the liquid phase contains dissolved monomers that polymerized during hardening process. In this study, a series of dual-setting cements were prepared by mixing dicalcium phosphate dihydrate (DCPD) as a solid phase and sodium silicate solution (SS) with different concentrations as hardening liquids. The idea was to evaluate the effect of SS concentration on the setting mechanism, physicochemical and mechanical properties of the formulated cements. The setting kinetics was attributed to the DCPD dissolution and calcium deficient hydroxyapatite (CDHA) precipitation in parallel to SS polymerization to form sodium silicate gel. This was responsible for the formation of an interpenetrating composite material in which the formed gel fills the micropores of the CPC cement. The results showed that the setting time can be modulated by varying the SS concentrates in the hardening liquid. It was shown, as the SS content in the cement liquid increased from 10 to 30 wt%, the setting time decreased from 56 to 5 min. Moreover, the DCPD dissolution and CDHA precipitation were accelerated by increasing the SS concentration. The bone-like apatite cement with the highest SS content exhibited an enhanced compressive strength and high resorption rates. Overall, the addition of sodium silicate gel is a promising approach to regulate the different properties of the apatite-forming cement to be used for bone fracture treatment.

Modeling Flexural and Compressive Strengths Behaviour of Cement-Grouted Sands Modified with Water Reducer Polymer

By using the American Society for Testing and Materials and British Standards standards, the impact of various grading of sand (Five types of sand) on the compressive strength (CS) of the cement grout (CG) treated with water reducer polymer is investigated. The properties of CG treated with polymer up to 0.16 % of cement weight were investigated and quantified in both fresh and hardened states. The water to cement ratio (w/c) was reduced by 21.9% to 54.1%, and the CG flow time was retained between 18 and 23 s. The highest compression strength was achieved at seven and 28 days for the cement-grouted sand using the coarser-graded sand than finer-graded sand at low w/c ranged between 0.50 and 0.53. The highest compression strength was obtained at high w/c for the cement grout mixed with the fine-grained sands compared to coarse-grained sands. Adding water reducer polymer enhances the compressive strength (σpc) and cylindrical compressive strength (σcc) by 113% to 577% and 53% to 459%, depending on mix proportion and curing period. An amorphous gel fills the porous places between the cement particles were formed when the CG was treated with water reducer polymer, which reduces voids, increases porosity, and increases the cement’s dry density; as a result, the CS of the CG increases significantly. To evaluate the CS of CG with different grain sizes, w/c, percentage of polymer, and curing age, linear and nonlinear techniques were used. according to the bs standard, the CS of the CG produced was 71% higher than that of the identical mix produced according to the ASTM standard. Compared to the other sands, the cement grout produced with finer sand grading had the maximum flexural strength at all testing ages.

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.

Breast Implant Engineering and Performance.

The engineering of breast implants for both augmentation and reconstruction is centered on facilitating optimal aesthetic results pleasing to the patient, while minimizing both short- and long-term complications. Some of the key individual design elements that have been the primary focus over time have included gel cohesivity, shell thickness, shell surface, and implant gel fill. A review of these separate elements points to the potential benefits of increased focus on a combined overall performance perspective for engineering of new implants as exemplified in the recently introduced MemoryGel Xtra Breast Implants. Such an approach is expected to provide an improved and expanded range of options to facilitate obtaining desired aesthetic outcomes and long-term clinical performance.

Theory of gel expansion to generate electrical energy

Mechanical-energy harvesters based on coiled carbon nanotube yarns are promising materials for sustainable energy generation. In this work, we present a novel mechanism to harvest energy from mechanical fluctuations by using coiled carbon nanotube yarns coated with polyelectrolyte gel. We developed a theory to explain how this new kind of energy harvesting is possible. The gel fills up all space between the coils and expands when the yarn is stretched. This translates into a change in electrical double-layer configuration, hence into a change in electrical potential. This makes it possible to electrochemically convert tensile or torsional mechanical energy into electrical energy. The influence of the yarn surface charge, polyelectrolyte charge density and salt concentration is analyzed, giving directions for optimum process design. We show calculation results for the generated power of a system consisting of two yarns coated with positive and negative polyelectrolyte gel.

Do chlorides qualify as accelerators for the cement of deepwater oil wells at low temperature?

In this paper, the acceleration performances and mechanisms of chlorides (CaCl2, LiCl and KCl) on oil well cement at low temperatures were studied. The results indicated that their accelerating ability follows the order of CaCl2>LiCl>KCl. CaCl2 has some unfavorable effects on the performance of cement, such as increasing the adiabatic temperature, causing bad rheology and thixotropy of cement slurry, and thickening the slurry, which may cause a “flash set”. LiCl can significantly enhance the compressive strength development of oil well cement stone at low temperatures like CaCl2, but do not have the disadvantages of CaCl2. Besides, LiCl can effectively shorten the static gel strength from 48Pa to 240Pa and also have much smaller adiabatic temperature. Based on the micro-test analyses, it was found that LiCl can accelerate the hydration rate of oil well cement under low temperatures. The hydration products of cement slurry include the ettringite (AFt), strip-shaped CSH gel (250–350nm) and strip-shaped CSH gel (50–70nm). The small spherical CSH gel fills in the pores of strip-shaped CSH gel to form a dense spatial structure. On contrast, the CSH gel forms a network structure in the cement containing CaCl2 or KCl. CaCl2 also inhibits the generation of AFt.

A medical device-grade T1 and ECV phantom for global T1 mapping quality assurance-the T1 Mapping and ECV Standardization in cardiovascular magnetic resonance (T1MES) program.

BackgroundT1 mapping and extracellular volume (ECV) have the potential to guide patient care and serve as surrogate end-points in clinical trials, but measurements differ between cardiovascular magnetic resonance (CMR) scanners and pulse sequences. To help deliver T1 mapping to global clinical care, we developed a phantom-based quality assurance (QA) system for verification of measurement stability over time at individual sites, with further aims of generalization of results across sites, vendor systems, software versions and imaging sequences. We thus created T1MES: The T1 Mapping and ECV Standardization Program.MethodsA design collaboration consisting of a specialist MRI small-medium enterprise, clinicians, physicists and national metrology institutes was formed. A phantom was designed covering clinically relevant ranges of T1 and T2 in blood and myocardium, pre and post-contrast, for 1.5 T and 3 T. Reproducible mass manufacture was established. The device received regulatory clearance by the Food and Drug Administration (FDA) and Conformité Européene (CE) marking.ResultsThe T1MES phantom is an agarose gel-based phantom using nickel chloride as the paramagnetic relaxation modifier. It was reproducibly specified and mass-produced with a rigorously repeatable process. Each phantom contains nine differently-doped agarose gel tubes embedded in a gel/beads matrix. Phantoms were free of air bubbles and susceptibility artifacts at both field strengths and T1 maps were free from off-resonance artifacts. The incorporation of high-density polyethylene beads in the main gel fill was effective at flattening the B1 field. T1 and T2 values measured in T1MES showed coefficients of variation of 1 % or less between repeat scans indicating good short-term reproducibility. Temperature dependency experiments confirmed that over the range 15–30 °C the short-T1 tubes were more stable with temperature than the long-T1 tubes. A batch of 69 phantoms was mass-produced with random sampling of ten of these showing coefficients of variations for T1 of 0.64 ± 0.45 % and 0.49 ± 0.34 % at 1.5 T and 3 T respectively.ConclusionThe T1MES program has developed a T1 mapping phantom to CE/FDA manufacturing standards. An initial 69 phantoms with a multi-vendor user manual are now being scanned fortnightly in centers worldwide. Future results will explore T1 mapping sequences, platform performance, stability and the potential for standardization.Electronic supplementary materialThe online version of this article (doi:10.1186/s12968-016-0280-z) contains supplementary material, which is available to authorized users.

Fabrication of the replica templated from butterfly wing scales with complex light trapping structures

The polydimethylsiloxane (PDMS) positive replica templated twice from the excellent light trapping surface of butterfly Trogonoptera brookiana wing scales was fabricated by a simple and promising route. The exact SiO2 negative replica was fabricated by using a synthesis method combining a sol–gel process and subsequent selective etching. Afterwards, a vacuum-aided process was introduced to make PDMS gel fill into the SiO2 negative replica, and the PDMS gel was solidified in an oven. Then, the SiO2 negative replica was used as secondary template and the structures in its surface was transcribed onto the surface of PDMS. At last, the PDMS positive replica was obtained. After comparing the PDMS positive replica and the original bio-template in terms of morphology, dimensions and reflectance spectra and so on, it is evident that the excellent light trapping structures of butterfly wing scales were inherited by the PDMS positive replica faithfully. This bio-inspired route could facilitate the preparation of complex light trapping nanostructure surfaces without any assistance from other power-wasting and expensive nanofabrication technologies.

The biology and evolution of cohesive gel and shaped implants.

The introduction of the silicone gel implant in 1962 began the modern era of breast augmentation, and over the past 50 years, breast implants have evolved to encompass a wide array of commercially available implants today. In April 1992, the moratorium on silicone gel breast implants began, and much of the experience and development of the cohesive shaped implants occurred outside the United States. During this time, saline implants were used almost exclusively in North America, whereas silicone implants continued to be used throughout the rest of the world. In 2001, cohesive gel implants became available in the United States under an Investigational Device Exemption Study. Three companies have US Food and Drug Administration approval of fifth-generation implants: Sientra, Allergan, and Mentor. These implants are unique due to the texture of the shell, implant dimensions, gel-shell interaction, gel fill ratio, degree of cross-linking, and form stability. Although form stability is a relative term, it may best be reserved to describe the increased ability of the implant to maintain its basic, intended shape. The cross-linking, form stability, and cohesiveness of these fifth-generation implants provide surgeons with an innovative tool to more closely create a natural breast in both shape and softness.

Treatment of severe osteochondral defects of the knee by combined autologous bone grafting and autologous chondrocyte implantation using fibrin gel

PurposeSevere symptomatic and unstable osteochondral defects of the knee are difficult to treat. A variety of surgical techniques have been developed. However, the optimal surgical technique is still controversial. We present a novel technique in which autologous bone grafting is combined with gel-type autologous chondrocyte implantation (GACI).MethodsIsolated severe osteochondral defects of the medial or lateral femoral condyle were treated by a two-step procedure. Firstly, chondrocytes were harvested during arthroscopy and cultured for 6 weeks. Secondly, a full thickness corticospongious autologuos bone graft, harvested from the medial or lateral femur condyle, is impacted in the defect and covered by GACI. The fibrin gel fills up to the exact shape of the chondral lesion and polymerizes within 3 min after application.ResultsFrom 2009 to 2011, 9 patients, median age 35 years (range 23–47), were treated by the combined autologous bone grafting and GACI technique. Median defect size was 7.1 cm2 (range 2.5–12.0), and median depth of the lesion was 0.9 cm (range 0.8–1.2). Median follow-up was 9 months (range 6–12 months). Six patients were available for 12-month follow-up. The mean IKDC score showed a 6-month improvement from 35 (SD ± 16) to 51 (SD ± 18) (n = 9; p = 0.01), and a 1-year improvement from 35 (SD ± 16) to 57 (SD ± 20) (n = 6; p = 0.03). The mean KOOS improved from 44 (SD ± 16) to 62 (SD ± 19) (n = 9; p = 0.07) at 6-month follow-up and from 44 (SD ± 16) to 65 (SD ± 24) (n = 6; p = 0.1) at 12-month follow-up. There was one failure that needed conversion to a unicompartmental knee arthroplasty.ConclusionCombined autologous bone grafting and GACI may offer an alternative surgical option for severe and unstable osteochondral defects of the knee.Level of evidenceIV.

Unsaturated hydraulic properties of cemented tailings backfill that contains sodium silicate

Recycling the mine waste (tailings) into cemented tailings backfill has economical and environmental advantages for the mining industry. One of the most recent types of cemented tailings backfill is gelfill (GF), a backfill that contains sodium silicate as chemical additive. GF is typically made of tailings, water, binder and chemical additives (sodium silicate gel). It is a promising mine tailings backfill technology. From a design point of view, the environmental performance or durability of GF structures is considered as a key factor. Due to the fact that GF structures are cementitious tailings, their durability and environmental performance depend on their ability to resist the flow of aggressive elements (water and oxygen). Thus, understanding the unsaturated hydraulic properties of GF is essential for a cost-effective, environmentally friendly and durable design of GF structures. However, there is a lack of information with regards to unsaturated hydraulic properties of GF, the factors that affect them and their evolution with time. Hence, the unsaturated hydraulic properties (water retention curve (WRC) or water characteristic curve, air entry value (AEV), residual water content, unsaturated hydraulic conductivity) of GF are investigated in this paper. GF samples of various compositions and cured in room temperature for different times (3, 7, 28, and 90 days) are considered. Saturated hydraulic conductivity and microstructural tests have been conducted; WRCs are measured by using a WP4-T dewpoint potentiameter and the saline solution method. Unsaturated hydraulic conductivity is predicted using the van Genuchten (1980) equation. The water retention curve (WRC) is determined as the relationship between volumetric water content and suction for each GF mix and curing time. The van Genuchten (1980) equation is used to simulate the WRC to best-fit the experimental data. AEV and residual water content are also computed for each mix and curing time. Furthermore, functions are developed to predict the evolution of AEVs, residual water content and fitting parameters of the van Genuchten model with degree of hydration. Important outcomes have been achieved with regards to unsaturated hydraulic properties. The unsaturated hydraulic conductivity of GF was calculated to decrease when the suction, binder content, and degree of hydration increase. The effects of binder content and degree of hydration are more obvious at low suction ranges. The obtained results would contribute to a better design and assessment of the durability and environmental performance of GF structures.

Cutaneous manifestation of silicone dissemination from a PIP implant - a case for prophylactic explantation?

The recent withdrawal of PIP (Poly Implant Prosthese, France) implants for breast augmentation enforced by the Medicines and Healthcare products Regulatory Agency (MHRA) on 31st March 2010 has ignited speculation into possible side effects relating to an unauthorized gel fill content. Local and migratory silicone granulomata and regional lymphadenopathy are well reported in the literature. Gel bleed from high cohesive gel implants with similar effect is also well known. However dissemination to sites distant from the breast manifest as cutaneous abnormalities in a patient implanted with a PIP product raises concern. We report such a case.

The pore structure and hydration performance of sulphoaluminate MDF cement

The hydration and pore structure of sulphoaluminate MDF cement were studied by X-ray diffractometer (XRD), scanning electron microscope (SEM) and mercury intrusion porosimeter (MIP) etc. The experimental results indicate that hydration products of the materials are entringites (AFt), aluminium hydroxide and CSH (I) gel etc. Due to its very low water-cement ratio, hydration function is only confined to the surfaces of cement grains, and there is a lot of sulphoaluminate cement in the hardenite which is unhydrated yet. Hydration reaction was rapidly carried under the condition of the heat-pressing. Therefore cement hydrates AFt, CSH (I) and aluminium hydroxide gel fill in pores. The expansibility of AFt makes the porosity of MDF cement lower (less than 1 percent) and the size of pore smaller (80 percent pore was less than 250A), and enhances its strength.

Vertical migration of137Cs in certain soils of Uzbekistan

The characteristic features and quantitative parameters of the vertical migration and distribution of t37Cs in soil samples from several territories of Uzbekistan, which are preserves and which have been affected by anthropogenic activity (Table 1), are investigated in this work. The samples were obtained in 1 cm thick soil layers with an average depth of 0.5, 1.5, 2.5, 3.5, 4.5, 7.5, 10.5, and 20.5 cm. The soil density averaged over the sampling depth was 140(O1700 gaiter. Extraneous matter was removed from the samples obtained, and the samples were reduced to an air-dry state, pulverized, sifted, and placed into 1 liter MarineUi vessels. The measurements were performed using a gamma spectrometer with a Ge(Li) detector with a 100 cm 3 sensitive volume and 6.2 keV energy resolution on the 1332 keV line. The detector was placed in lead shielding. An LPA 4910.2 linear amplifier and a PA001 amplitude-to-digital converter combined with an IBM PC were used in the spectrometric channel (Joint Institute of Nuclear Research, Dubna). The data were recorded, accumulated, and processed using the MARS code system (Joint of Institute of Nuclear Research). A standard collection of special standard activity measures was used to determine the "y-ray detection efficiency [2]: 134Cs ' 137Cs ' 226Ra ' 232Th, and 4~ with silica gel (9 = 980 gaiter) and quartz sand (p = 1800 gaiter) fills, placed in Marinelli vessels. The measurement time of the spectra for individual samples was 3-12 h, and the energy range was 150--1500 keV. Measurement Results. The 661 keV photopeaks of 137Cs were observed in the spectra of samples taken from the upper layers of all soils investigated, with the exception of samples from a recultivated area. The photopeaks of the natural radionuclides were present in the spectra of all samples. The specific activity C a, the 137Cs store q.r = C.vl3a AX in the investigated layers of thickness AX, and the store per unit t/ surface area of the soil Q = ~qx, where n is the number of layers and 9s is the density of the soil in the xth layer (C x for the A=l intermediate layers which were not investigated is determined by interpolation), were determined from the area of the 661 keV photopeaks in the spectra of the samples taking into account the quantum yield, detection efficiency, sample mass, and measurement duration. The specific activity of 137Cs in the soils investigated does not exceed 151 Bq/kg, and the store per unit surface area of soil with undisturbed profiles is 2-3.9 kBq/m 2 (Table 2). The error in determining the values does not exceed 20%. The specific activity of natural radionuclides in the soil layers investigated shows a much smaller variation. Thus, for

Elastic properties of silica aerogels from a new rapid supercritical extraction process

Silica aerogels were produced by a new process from tetramethoxysilane (TMOS) with ammonia as base catalyst. The process involves pouring the liquid sol in a stainless steel mold and immediately heating to supercritical conditions. Gelation and aging occur during heating and reaction rates are high due to high average temperatures. The gel fills the container completely, which enables relatively fast venting of the supercritical fluid by providing a constraint for swelling and failure of the gel monolith. The whole process can be completed within 1 h. Longitudinal and shear moduli were measured in the dried aerogels by ultrasonic velocity measurements both as a function of chemical composition of the original sol and of position in the aerogel. The sound velocity exhibits marked maxima close to the edges of the cylindrical, where the fluid left during venting. Specimens with high catalyst concentration and high water:TMOS ratio exhibited higher average moduli.

COMPARISONS OF USING ELECTRIC POLLINATOR OR BOMBUS IMPATIENS FOR POLLINATING HYDROPONICALLY GROWN TOMATOES

A successful greenhouse tomato crop depends on the optimization of several factors; among these factors are water, nutrition, and all facets of environmental control. Good pollination, however, is one of the most important requirements for the production of fruit of high yield and quality. Poor pollination causes fruit that are smaller, angular, or puffy, due to reduced seed numbers and poor gel fill in the locules. In Spring 1993, two 7.3 × 29.3 double plastic-covered greenhouses were used to compare the conventionally used electric pollinator to bumblebees for effective pollination; replicated variety trials were performed within each. In one greenhouse (12 replications, RCBD), `Trust' performed better than `Caruso' in yield and quality, although it was smaller in fruit size. In the other greenhouse (four replications, RCBD), `Match' and `Switch' were better than all others (`Belmondo', `Capello', `Laura', and `Rakata') for most yield and quality variables. Means across varieties were similar for the two pollination techniques, with marketable weights identical. For gutter-connected greenhouse ranges of 0.1 ha or larger, bumblebees are an economically viable option for pollinating hydroponically grown tomatoes.