Cement Surface Research Articles

PEEK Surface Treatment Using Nd: YAG, Riboflavin Activated by PDT, and Alumina Particles on Surface Roughness, Bond Failure, and Bond Integrity to Composite Resin

Aims: Conditioning protocols, Airborne Particles of Alumina (ABP), Neodymium-Doped Yttrium Aluminium Garnet (Nd: YAG) laser, and Riboflavin (RF), were tested on PEEK disc bonded to composite restorations for surface roughness (Ra) and shear bond strength (SBS). Method and Material: Random sampling was used to divide 80 PEEK discs into four groups for surface conditioning. (n = 20). Group 1: Sulfuric acid (SA); Group 2: PDT (RF); Group 3: Alumina particle ABP; Group 4: NYL. Pretreated PEEK discs were measured for Ra using a surface profilometer. They were luted and bonded to composite resin discs. On Universal testing equipment, SBS was tested. Stereomicroscopes analyzed failure type. Data was analyzed using one-way ANOVA and Tukey’s test. Results: The SA-treated group had the highest Ra (1.411 ±0.043 μm). However, PDT (RF) treated tissues had the lowest mean Ra score (1.299 ± 0.019 μm). Regarding SBS, the SA-treated group (11.83±0.82 MPa) had the highest mean score. PDT (RF) (10.23±0.64 MPa) treated specimens showed the lowest bond integrity values. The most common fracture type in all investigated groups is cohesive failure. Conclusion: Airborne alumina, riboflavin, and Nd: YAG laser could replace PEEK sulfuric acid to improve composite cement bond integrity and surface roughness.

Short‐term length change measurements and sorption isotherms for AAC compared to OPC

AbstractThe interaction of adsorbed water with the microstructure of cementitious materials leads to effects on macroscopic properties. However, precise quantitative correlation of adsorbed water with short‐term changes in macroscopic properties, such as dimensional changes, remains a challenge. We compare recent results from precise dual‐microscope‐based short‐term length change measurements and discuss differences in length‐change isotherms and adsorption isotherms arising from various cement types. Water vapor adsorption happens already at very low humidity in the interlayer space of the C‐S‐H gel. Adsorption and desorption on cement surfaces due to changing relative humidity induces strong forces in the cement gel, leading to detectable changes in dimensional stability for the hardened material. A significant hysteresis in the water desorption isotherm is often accompanied by hysteresis in dimensional change as well. For precise length change measurements, an optical method for tracking surface patterns on thin cement slices was applied. Short‐term length change results are compared to corresponding water vapor sorption isotherms and pore size measurements. Hypotheses and conclusions regarding microstructural changes and shrinkage mechanisms are discussed in order to understand the experimental data.

Phosphorylated chitosan as a hydrosoluble additive for bioactive calcium carbonate cements: Elaboration, setting mechanism, and handling properties

Chitosan is extensively used in the biomedical field owing to its biocompatibility and degradability. However, its limited solubility hinders its use as an effective additive in bone mineral cements. This study aimed to synthesize water-soluble phosphorylated chitosan and introduce it in calcium carbonate cement in view to control the composition, in vitro bioactivity, and physicochemical properties of the cement for bone repair. NMR spectroscopy results showed that chitosan was selectively functionalized (Cs–P) with phosphate groups mainly grafted at the C6 position on the chitosan backbone. For the first time, phosphorylated chitosan was associated with calcium carbonate cement; it was dissolved in a Na2CO3 solution (liquid phase of the cement) used as a setting accelerator. The quantitative XRD analysis at different time points revealed that the dissolution-recrystallization mechanism involved in the paste setting and hardening was different than for the reference cement: composite cement including 2.5 wt% Cs–P was mainly composed of vaterite (74 wt%) stabilized by Cs–P and some magnesian calcite (26 wt%). We pointed out the pivotal role of the calcium-binding ability of Cs–P phosphate groups and also of magnesium in controlling the cement setting mechanism and properties and its evolution in SBF. Interestingly, this composite cement also exhibited good physicochemical and handling properties: short initial (17 min) and final (28 min) setting times, high injectability (95%), enhanced anti-washout resistance of the paste, and a compressive strength compatible with implantation in non-load bearing bone defects. The in vitro evolution of the composite cement in SBF solution revealed some apatite formation on the cement surface and a high resorption rate (>20% at 28 days) owing to the solubility of the vaterite polymorph, making this composite cement a promising resorbable and bioactive ceramic able to be implanted through a minimally invasive technique.

Study on noise behavior of micro-textured composite coated cemented carbide surface grinding titanium alloy based on HHT analysis

In modern industrial production, noise can reflect the cutting state of the workpiece and tool to a certain extent, and the noise collection method cannot interfere with the complex processing environment. To further improve the cutting performance of coated cemented carbide micro-textured tools, this paper builds a friction and wear test platform for micro-textured cemented carbide pins with AlSiTiN-AlCrN coating and titanium alloy discs. Based on the test noise signal, the relationship between friction and wear and the noise of the workpiece was studied by the Hilbert–Huang transform (HHT). Through the change of noise in different periods, the micro-texture and coating life of cemented carbide pin under other processing parameters were analyzed. Based on the influence of the interaction between processing parameters and micro-texture diameter on the test results, the test parameters were optimized. The results show that the change of noise signal during the test presents a “V” curve with the grinding process, which mainly affects the noise through the shift of pin-disc friction form and the anti-wear effect of micro-texture. The interaction mainly affects the test results by affecting the micro-texture diameter, laser energy concentration, and the roughness of the inner wall of the pit. The optimized micro-texture geometry and preparation parameters are as follows: scanning times is 8, micro-texture diameter is 50 μm, scanning speed is 1500 mm/s, micro-texture spacing is 170 μm, and laser power is 40 W. The research content of this paper provides a reference for improving the surface properties of cemented carbide.

Geochemical behaviors of uranium and thorium during weathering and pedogenesis of carbonate rock: constraint from their speciation.

During weathering and pedogenesis of carbonate rock with poor-uranium (U) and thorium (Th), U and Th present the characteristics of strong leaching (especially U) and significant residual enrichment, the cause of which is still unclear. In this paper, a weathering profile developed by dolomite in karst area of Guizhou province in southwest China was selected, which showed zonation characteristics of bedrock (Y), powdery rock (Yf), and soil layer (T1 to T12) from the bottom to up. Through the determination of the occurrence speciation of U and Th in Y and weathering profile, combined with mineralogical, geochemical characteristics, and element mass balance calculation, the constraints of U and Th speciation on the geochemical behavior of U and Th during the weathering of carbonate rock were revealed. The results proved that U and Th in Y preferentially existed in acid insoluble phase, for example, the contents of U and Th in Y were 0.90 mg·kg-1 and 0.28 mg·kg-1, respectively, while those in acid insoluble matter were 2.34 mg·kg-1 and 2.57 mg·kg-1, respectively, but because the mass percentage of acid insoluble matter was extremely low (0.95%), the mass percentages of U and Th in the acid soluble phase in the whole rock were absolutely superior (96% of U and 86% Th). The U and Th in the acid soluble phase of Y were mainly adsorbed on the crystal surface of carbonate minerals or existed in the cement, and the U and Th in the carbonate lattice only accounted for a small proportion. From Y to Yf with the initial dissolution, U and Th released from the surface of carbonate minerals and cements were in carbonate-rich alkaline environment, and these portions of U and Th were leached out, resulting in strong loss of U and Th in the Yf (the loss rates are 83% of U and 65% of Th, respectively). From the Yf to the overlying soil layer T1, the carbonate components were completely dissolved, and the U and Th released from the carbonate lattice showed different behaviors, where U was completely leached and Th tended to stay in the weathered residue. Thus, in the soil layer T1 formed by Y or Yf , the residual U was the inheritance of the U in the acid insoluble phase of Y; For Th, it not only inherited the Th of acid insoluble phase of Y, but also superimposed the Th from carbonate lattice in Y. On the other hand, during the evolution process from Y to Yf and to soil layer T1, with the dissolution of carbonate, the acid insoluble phase also showed a significant tendency of chemical weathering. However, the U and Th in the Y acid insoluble phase were not leached with the decomposition of the acid insoluble phase but were redistributed among the residual phases. For the geochemical behaviors of U and Th in the evolution of soil profile (T1~T12), they were subjected to the occurrence speciation of U and Th in T1 and the change of U and Th occurrence speciation with the upward direction of soil profile. The U and Th released from the carrier minerals were mainly redistributed among the residual solid phases, which weakened the intensity of their further loss. This study deepens the understanding of the geochemical behavior of radionuclides in karst environment and provides reference for the treatment of radioactive pollution in karst areas.

Passive-Cooling Building Coating with Efficient Cooling Performance and Excellent Superhydrophobicity.

Passive-cooling building materials can achieve cooling without external energy consumption, which is an energy-saving and environmentally friendly cooling method. However, the existing passive-cooling building materials have the limitations of high cost, complicated processes, and a toxic organic solvent, which hinders the passive-cooling technology applied in practical building. To overcome these limitations, we developed a facile, high-efficiency, non-toxic, and superhydrophobic passive-cooling building coating (SPCBC) with an efficient cooling capability and excellent durability that was composed of polydimethylsiloxane and SiO2. The fabricated SPCBC demonstrated a high reflectance and a high emittance, showing a superior cooling capability with a 14 °C temperature drop compared with a bare cement surface on a hot summer day. In addition, the SPCBC could not be wetted or contaminated by muddy water, corrosive aqueous solutions, or dust, which presented an excellent anti-fouling and self-cleaning capability. Moreover, the fabricated SPCBC could work outdoors for 30 days, withstand UV irradiation for 30 days, and resist accelerated aging for 100 h without any significant changes in the superhydrophobicity and the cooling capability, meaning that the SPCBC had an outstanding durability. This work provides a new method to facilitate passive-cooling technology to apply in practical building in hot weather regions of the world.

Simulation and experimental study of ultrasonic-assisted shear thickening polishing of cemented carbide

In order to obtain a good surface quality of carbide inserts, an ultrasonic-assisted shear thickening polishing (UASTP) method is proposed in this paper. Using the shear thickening property of non-Newtonian fluids and combining with the principle of ultrasonic vibration, the abrasive grains wrapped by the polishing slurry carry out both flexible micro-cutting and high-frequency micro-collision on the material surface. This enables more efficient polishing of the microscopic surface of the material. In this paper, the polishing principle of this method is analyzed. The rheological characteristics of shear thickening polishing slurry are studied, and a continuity model that can adapt to nonlinear rheological behavior is proposed based on the Gross constitutive equation. The effects of fluid velocity, ultrasonic amplitude and ultrasonic frequency on polishing speed and polishing pressure in the Preston equation are studied by COMSOL Multiphysics simulation software. This method's material removal rate model is established based on the high-frequency periodic characteristics of ultrasonic action, combining the simulation results with polishing experiments, which accurately describe the variation law of material removal rate with polishing time. After polishing the carbide insert for 60 min with this method, a smooth surface is obtained with continuous surface ripple measurements and small floating values; the surface roughness is reduced from 195 nm to 16.1 nm with an improvement rate of 91.7 %, and the material removal rate reached 0.71 μm/h, which improved the surface roughness improvement rate and material removal rate by 27.6 % and 44.9 %, respectively, compared with the STP method. The experimental results show that the UASTP method is an efficient composite polishing technology to enhance the cemented carbide's surface quality further.

Physical, Mechanical, and Biological Properties of PMMA-Based Composite Bone Cement Containing Silver-Doped Bioactive and Antibacterial Glass Particles with Different Particles Sizes.

In the present work, antibacterial composite bone cement was designed by introducing a bioactive and antibacterial glass into a commercial formulation. The effect of glass particles' addition on the curing parameters of the polymeric matrix was evaluated; moreover, the influence of the glass particle size on the glass dispersion, compressive and bending strength, bioactivity, and antibacterial effect was estimated. The results evidence a delay in the polymerization kinetics of the composite cement, which nevertheless complies with the requirements of the ISO standard. Morphological characterization provides evidence of good dispersion of the glass in the polymeric matrix and its exposition on the cement surface. The different glass grain sizes do not affect the composites' bioactivity and compressive strength, while a slight reduction in bending strength was observed for samples containing glass powders with greater dimensions. The size of the glass particles also appears to have an effect on the antibacterial properties, since the composites containing larger glass particles do not produce an inhibition halo towards the S. aureus strain. The obtained results demonstrate that, by carefully tailoring the glass amount and size, a multifunctional device for artificial joint fixing, temporary prostheses, or spinal surgery can be obtained.

Analysis of the Multiwalled Carbon Nanotubes Reinforced Polymethyl Methacrylate Bone Cement’s Characteristics and In Vitro Bioactivity to Prolong Its Functionality in Orthopedic Application

Polymethyl methacrylate (PMMA) bone cement is being used to fill voids that are created due to vertebral compression fractures. It is also a grouting medium in orthopedic joint replacement surgeries as they possess fast primary fixation to the bone. Considering the cement properties and in vitro bioactivity of bone cement is essential for cemented hip and knee joint replacement surgeries. In this study, commercial Simplex P bone cement (SPBC) is modified with carboxyl- (-COOH-) functionalized multiwalled carbon nanotubes (MWCNTs) to overcome high polymerization temperature, volumetric shrinkage, surface wettability, and in vitro bioactivity. A geometric dilution method is used to incorporate MWCNTs with the PMMA powder, which is in unequal proportions. The PMMA/MWCNT nanocomposite with different concentrations of reinforcements, such as 0.1, 0.3, 0.5, and 0.7 weight percentages, is prepared for the investigation. It was observed that the MWCNTs had a beneficial impact on PMMA bone cement (PMMA-BC) by enhancing its setting time (2.94%↑) and surface wettability (23.58%↑). Also, diminished polymerization temperature (29%↓) and volumetric shrinkage (40.9%↓) are observed for an optimum concentration of 0.7 wt. %. The bioactivity of the cement surface is validated by the in vitro bioactivity observed in simulated body fluid (SBF) through the development of primary and secondary apatite. It is concluded that the synthesized PMMA/MWCNT nanocomposites are found to have enhanced cement properties compared to PMMA-BC.

Comparison of antibiotic-impregnated bone cement coverage versus vacuum sealing drainage in semi-open bone grafting using for tibial fracture with infected bone and soft tissue defect: a retrospective analysis

ObjectiveTo compare antibiotic-impregnated bone cement coverage (bone cement surface technique; BCS-T) versus vacuum sealing drainage (VSD) for tibial fracture with infected bone and soft tissue defect.MethodThis retrospective analysis compared the clinical outcomes in patients undergoing BCS-T (n = 16) versus VSD (n = 15) for tibial fracture with infected bone and soft tissue defect at the Third Hospital of Hebei Medical University from March 2014 to August 2019. For BCS-T group, osseous cavity was filled with autograft bone graft after debridement, and then the wound was covered with a 3-mm layer of bone cement impregnated with vancomycin and gentamycin. The dressing was changed every day in the first week, and every 2 ~ 3 days in the second week. For VSD group, a negative pressure of -150 ~ -350 mmHg was maintained, and the dressing was changed every 5–7 days. All patients received antibiotics treatment based on bacterial culture results for 2 weeks.ResultsThe 2 groups did not differ in age, sex and key baseline characteristics, including type of Gustilo-Anderson classification, size of the bone and soft tissue defect, the percentage of primary debridement, bone transport, and the time from injury to bone grafting. The median follow-up was 18.9 months (range:12–40). The time to complete coverage of bone graft by granulation tissue was 21.2 (15.0–44.0) and 20.3 (15.0–24.0) days in the BCS-T and VSD groups, respectively (p = 0.412). The 2 groups also did not differ in wound healing time (3.3 (1.5–5.5) versus 3.2(1.5–6.5) months; p = 0.229) and bone defect healing time (5.4(3.0-9.6) versus 5.9(3.2–11.5) months; p = 0.402). However, the cost of covering material was significantly reduced in the BCS-T group (2071 ± 134 versus 5542 ± 905 yuan; p = 0.026). Paley functional classification at 12 months did not differ between the 2 groups (excellent in 87.5% versus 93.3% in the 2 groups; p = 0.306).ConclusionBCS-T could achieve clinical outcomes similar to VSD in patients receiving bone graft for tibial fracture with infected bone and soft tissue defect, but material cost was significantly reduced. Randomized controlled trials are needed to verify our finding.

Photocatalytic and Antimicrobial Activity of TiO2 Films Deposited on Fiber-Cement Surfaces

In this study, TiO2 films were deposited via the doctor blade technique on fiber-cement surfaces. Two types of nanoparticles (TiO2-P25 from Degussa and TiO2-PC105 from Tronox) were used to produce films. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images revealed films with homogeneous and nanoparticulated morphology. The TiO2 PC105 film presented a lower roughness parameter (RMS) in relation to that of the TiO2 P25-based film. Both films exhibited high hydrophilicity when exposed to UV-A radiation (contact angle θ < 6°). The photocatalytic activity of the films was evaluated by standardized methylene blue dye degradation assays under UV-A irradiation (1.0 mW/cm2). The TiO2-PC105 film showed a photonic efficiency of ξ = 0.1%, while for the films obtained with TiO2-P25, ξ = 0.08%. The cement surface modified with the PC105 film was evaluated for antimicrobial activity through the use of multiple pathogens commonly found in hospitals. A considerably high efficiency was measured with visible light. Growth inhibition rates of 99.0% ± 0.2, 99.1% ± 0.2, 99.1% ± 0.2, 97.5% ± 0.5, 98.0% ± 0.5 and 98.0% ± 0.5 were found for Staphylococcus aureus, Klebsiella sp., Escherichia coli, Rhizobium sp., Fusarium sp. and Penicillium sp., respectively. The results show the self-cleaning ability and their potential use for protection, by preventing contamination of the fiber-cement surface and opening new possibilities for the use of this building material.

Influence of surface characteristics of implant materials on MRSA biofilm formation and effects of antimicrobial treatment.

One of the main causes of treatment failure in bacterial prosthetic joint infections (PJI) is biofilm formation. The topography of the biofilm may be associated with susceptibility to antimicrobial treatment. The aims of this study were to assess differences in topography of biofilms on different implant materials and the correlation thereof with susceptibility to antimicrobial treatment. Methicillin-resistant Staphylococcus aureus (MRSA) 7-day mature biofilms were generated on disks made from titanium alloys (Ti-6Al-7Nb and Ti-6Al-4V), synthetic polymer and orthopedic bone cement, commonly used in implant surgery. The surface topography of these implant materials and the biofilms cultured on them was assessed using atomic force microscopy. This provided detailed images, as well as average roughness (Ra) and peak-to-valley roughness (Rt) values in nanometers, of the biofilm and the material surfaces. Bacterial counts within biofilms were assessed microbiologically. Antimicrobial treatment of biofilms was performed by 24-h exposure to the combination of rifampicin and ciprofloxacin in concentrations of 1-, 5- and 10-times the minimal bactericidal concentration (MBC). Finally, treatment-induced differences in bacterial loads and their correlation with biofilm surface parameters were assessed. The biofilm surfaces on titanium alloys Ti-6Al-7Nb (Ra = 186 nm) and Ti-6Al-4V (Ra = 270 nm) were less rough than those of biofilms on silicone (Ra = 636 nm). The highest roughness was observed for biofilms on orthopedic bone cement with an Ra of 1,551 nm. Interestingly, the roughness parameters of the titanium alloys themselves were lower than the value for silicone, whereas the surface of the bone cement was the roughest. Treatment with 1- and 5-times the MBC of antibiotics resulted in inter-material differences in colony forming units (CFU) counts, ultimately showing comparable reductions of 2.4-3.0 log CFU/mL at the highest tested concentration. No significant differences in bacterial loads within MRSA biofilms were observed between the various implant materials, upon exposure to increasing concentrations of antibiotics. The surface parameters of MRSA biofilms were determined by those of the implant materials on which they were formed. The antibiotic susceptibility of MRSA biofilms on the various tested implant materials did not differ, indicating that the efficacy of antibiotics was not affected by the roughness of the biofilm.

First occurrence in life position of two Triassic brachiopod species (Thecideida) from NE Italy: Paleoecological considerations

The San Cassiano Formation from the Dolomites, NE Italy, is a Ladinian–Carnian (Middle – Upper Triassic) lithostratigraphic unit belonging to the Western Tethys domain. In this formation numerous groups of marine invertebrates from reef communities have been reported. In particular, brachiopods are represented by different orders. Thecideids are the most abundant and diverse, with different species of the genus Thecospira. Despite the apparent abundance, only one report exists of a thecideid of the genus preserved in life position: Thecospira tyrolensis. In this study, we describe and discuss the first finding of Thecospira semseyi and Thecospira tenuistriata in life position based on the study of thin sections of Cipit boulders. Seemingly, the Th. semseyi shells were not firmly attached to the substrate by a small cementation surface; therefore, they could have lived embedded into the biogenic matrix. By contrast, Th. tenuistriata displays an umbonal region modified in a cementation area, allowing the attachment to the bio-builder. Most samples don’t show any signal of transport since all specimens are articulated and are still attached to the substrate. Besides, the commissures are partially opened, free of any encrustation of sponge or bryozoan growing. The preservation of brachiopods suggests that the samples of both species were fossilized in life position. Moreover, Th. semseyi and Th. tenuistriata continued to live although the host’s fabric was imbibing the brachiopods’ ventral valve. This shows that thecideids were important components of Tethys reef communities.

Effect of different surface treatment protocols on the bond strength between lithium disilicate and resin cements.

Because the use of hydrofluoric acid (HF) poses health risks if handled improperly, many clinicians prefer to have the ceramic restorations pre-etched in dental laboratories. However, during the try-in procedure, the pre-etched glass-ceramic restorations may be contaminated with saliva resulting in reduced bond strength. This in-vitro study aimed to investigate the effect of different surface treatments on the bond strength of lithium disilicate (LD) glass-ceramic restorations (IPS e.max Press, Ivoclar Vivadent) to two resin cements. One-hundred eighty blocks (4X4X3mm) of LD glass-ceramic were divided into twelve groups (n = 15), of which six received Variolink Esthetic DC (VE) cement and six received RelyX Ultimate (RU) cement, following the surface treatments: G1) Control: Hydrofluoric Acid + Silane (HF + Sil); G2) Hydrofluoric Acid + Saliva + Silane (HF + S + Sil); G3) Hydrofluoric Acid + Saliva + Ivoclean + Silane (HF + S + IC + Sil); G4) Hydrofluoric Acid + Saliva + Phosphoric Acid + Silane (HF + S + P + Sil); G5) Hydrofluoric Acid + Saliva + Monobond Etch & Prime (HF + S + EP); G6) Monobond Etch & Prime (EP). Following treatment, a resin-cement cylinder (2.3mm diameter) was built on the glass-ceramic surface, photocured (20s), stored in distilled water (37°C, 24h) and submitted to the shear bond strength test. Bond strength data (MPa) were subjected to two-way ANOVA and Tukey (α = 0.01). Cement type and surface treatment had a significant effect on the bond strength (p < 0.001) (Table 4). Single-step Monobond Etch & Prime (EP) significantly improved the bond strength of resin-cements to glass-ceramic with and without saliva contamination.

Flow patterns of a resin repair material in a vertical wellbore microannulus

We studied the repair of a simulated wellbore microannulus between cement and steel using a resin repair material. The experimental configuration consisted of a rough cement surface and a transparent acrylic plate on top of it to serve as a surrogate for steel as it has similar wetting characteristics for the fluids of interest in this study. The microannulus was repaired in a vertical configuration, so the buoyant, capillary, hydrostatic and viscous forces affected the repair. The interaction among those forces determined the flow patterns that developed as the resin was injected into the microannulus and the efficiency of the repair. The microannulus was first saturated with water, and then resin repair material without hardener was injected at the bottom of the microannulus until it arrived at the top of the microannulus (“breakthrough”). The injection of the repair material was conditionally stable since the resin was less dense than water, but more viscous. If the injection velocity was great enough, the resin would effectively displace the water; if not, buoyant forces dominate, and flow became unstable. In addition, the aperture distribution of the microannulus added the complexity of varying capillary forces. The experiments revealed a wide range of behaviors as a function of injection velocity, from pulse flow with apparent saturation of resin at breakthrough of only 4.4% at low velocities to a much more compact displacement at higher velocities, achieving a 67.8% apparent saturation at breakthrough.

Fatty Alcohol Polyoxyethylene Ether Sodium Sulfate–Modified Cement to Improve the Bonding and Sealing of Cement to Oil-Wet Casing or Formation Surface in Shale Gas Wells

Summary In shale gas wells, oil-based mud (OBM) changes the casing and rock surface wettability during drilling. It negatively affects the bonding and sealing of cement sheaths with casing or formation rock. Although the spacer is widely used in primary cementing, the casing and formation rock surface are wetted by OBM or oil phase due to poor displacement. For this work, a novel oleophilic cement slurry modified by fatty alcohol polyoxyethylene ether sodium sulfate (AES) was investigated to decrease the negative effect of OBM- or oil-wetted surface. The contact angle of nonpolar solvent 1-bromonaphthalene on the cement surface decreased from 35° to 8°, showing an ideal oleophilic property. The hydraulic isolation capacity; microstructure of the cement-casing or cement-rock interface; and the pore structure, hydration, and mechanical property of AES-modified cement were investigated by interfacial hydraulic isolation test device, computed tomography (CT), mercury intrusion porosimetry (MIP), X-ray diffraction (XRD), thermogravimetric analyses (TGAs), and mechanical test. The results showed that the oleophilic cement could directly bond with an oil- or OBM-wetted surface and significantly eliminate the microchannel and connected pores caused by the oil phase or OBM on the interface. The fluid channeling on the OBM-wetted cement-rock and casing interface was prevented, and the sealing pressure of the interface was increased from approximately 3 to 7 MPa/m (fluid channeling occurred) to higher than 275 MPa/s (fluid channeling did not occur), respectively. Besides, the hydration degree, porosity, and mechanical property of the oleophilic cement remained at the same level as the conventional cement, indicating that the AES has no adverse effect on cement hydration and properties. The findings of this study can contribute to the cement slurry design in shale gas well cementing to improve the interface bonding and sealing when poor displacement happens.

Investigation of corrosion inhibitor used in cement

Steel bar corrosion inhibitor can be incorporated into concrete (or mortar) with a small amount, or coated on the cement surface to protect the steel materials. It can prevent or delay the corrosion of metal bars by directly acting on the steel bars in concrete (or mortar), but it does not affect the structure and properties of concrete. In this paper, the single component corrosion inhibitor was screened and evaluated at room temperature by salt water immersion test and static coupon weight loss method. The results show that hydrazine hydrate and KNO3 can effectively prevent the corrosion of reinforcement after being placed in simulated corrosion solution for 7 days. When the concentration of hydrazine hydrate and KNO3 is greater than 0.5%, the corrosion inhibition rate of KNO3 is 95.44% (100mg·L−1).

Photocatalytic Degradation of Methyl blue by TiO2 Nanoparticles Incorporated in Cement

In this study, titanium dioxide (TiO2) nanoparticles incorporated with cement were synthesis by a simple casting method as a function concentration of TiO2 (0.2, 0.4, 0.8, 1, and 2 wt%). The prepared samples were characterized using the technique of Field Emission Scanning Electron Microscope (FESEM) and UV-Visible spectrophotometer, which was used to measure the adsorption spectra. The observed photocatalytic efficiency of TiO2 nanoparticles (NP) incorporated with cement was investigated by decomposing the dye methyl blue (MB) solution under sunlight irradiation. According to the slope, the value of the k constant at the best sample is 0.8wt%, k=0.8265 min-1. FESEM image of the TiO2/cement with 0.8 wt% content show the TiO2 NPs were well-attached to cement particles, and they covered the cement surface. The increase in photocatalytic (PC) activity was due to an increase of TiO2 concentration in the cement, which best occur of 0.8 wt% of TiO2 in cement. The degradation at the MB (5ppm) was 98.864 % after 120 min under sunlight irradiation. The method involves easily and simply preparing TiO2/cement that is used in self-cleaning and studying the effect of different festive factors, including the concentration of the dye. The preparation of TiO2/cement was successful as a photocatalyst for a self-cleaning surface.

Photocatalytic Degradation of Methyl blue by TiO2 Nanoparticles Incorporated in Cement

In this study, titanium dioxide (TiO2) nanoparticles incorporated with cement were synthesized by a simple casting method as a function of the concentration of TiO2 (0.2, 0.4, 0.8, 1, and 2 wt%). The prepared samples were characterized using the techniques of Field Emission Scanning Electron Microscope (FESEM) and UV-Visible spectrophotometer, which were used to measure the adsorption spectra. The observed photocatalytic efficiency of TiO2 nanoparticles (NP) incorporated with cement was investigated by decomposing the dye methyl blue (MB) solution under sunlight irradiation. According to the slope, the value of the k constant at the best sample is 0.8 wt%, k = 0.8265 min-1. FESEM images of the TiO2/cement with 0.8 wt% content show the TiO2 NPs were well-attached to cement particles, and they covered the cement surface. The increase in photocatalytic (PC) activity was due to an increase in TiO2 concentration in the cement, which best occurs at 0.8 wt% of TiO2 in cement. The degradation at the MB (5 ppm) was 98.864 % after 120 min of sunlight irradiation. The method involves easily and simply preparing TiO2/cement that is used in self-cleaning and studying the effect of different festive factors, including the concentration of the dye. The preparation of TiO2/cement was successful as a photocatalyst for a self-cleaning surface.

Performance analysis of n-type PERT bifacial solar PV module under diverse albedo conditions

The additional gain in the energy yield of a bifacial solar photovoltaic (PV) module is mainly due to its ability to absorb the ground reflected irradiance (Albedo) through the rear surface of the module. Albedo is the critical characteristic that depends on the surface of the ground, the position of the sun, module clearance, module spacing, tilt angle, etc. The higher the value of albedo, the more is the bifacial gain and so the energy yield. This work investigates the performance of the ELAN series N-type passivated emitter rear totally diffused (PERT) bifacial PV module installed at latitude 9.673° N and longitude 77.964° E under diverse albedo conditions. The ground surface under the module is covered with different reflective materials and the performance parameters like albedo, bifacial gain, and the peak power output are calculated and compared. For aluminum reflective surface, the value of albedo is high and in the range of 0.50–0.57, with an average bifacial gain of 21.4%. The white reflective surface stands next with the value of albedo between 0.37 and 0.42, and an average bifacial gain of 18.9% followed by the reflective surfaces of cement, sand, and grass with an average bifacial gain of 12.8%, 7.8%, and 4.8% respectively. Depending upon the albedo and the bifacial gain, the bifacial solar PV produces the additional power gain. Overall, from the experimental results, it is observed that different reflective materials with different albedos produce different bifacial gain and peak output power depending on the operation conditions.