Gel Deposition Research Articles

A Non‐Volatile, Thermo‐Reversible, and Self‐Protective Gel Electrolyte Providing Highly Precise and Reversible Thermal Protection for Lithium Batteries

AbstractThe safety issue represents a long‐standing obstacle that retards large‐scale applications of high‐energy lithium batteries. Among different causes, thermal runaway is the most prominent one. To date, various approaches have been proposed to inhibit thermal runaway; however, they suffer from some intrinsic drawbacks, either being irreversible (one‐time protection), using volatile and flammable electrolytes, or delayed thermal protection (140–150 °C). Herein, this work exploits a non‐volatile, non‐flammable, and thermo‐reversible polymer/ionic liquid gel electrolyte as a built‐in safety switch, which provides highly precise and reversible thermal protection for lithium batteries. At high temperature, the gel electrolyte experiences phase separation and deposits polymer on the electrode surfaces/separators, which blocks Li+ insertion reactions and thus prevents thermal runaway. When the temperature decreases, the gel electrolyte restores its original properties and battery performance resumes. Notably, the optimal protection effect is achieved at 110 °C, which is the critical temperature right before thermal runaway. More importantly, such a thermal‐protection process can repeat multiple times without compromising the battery performance, indicating extraordinary thermal reversibility. To the authors' knowledge, such a precise and reversible protection effect has never been reported in any electrolyte systems, and this work opens an exciting avenue for safe operation of high‐energy Li batteries.

A Hybrid Approach to Surface Engineering Based on Laser Texturing and Coating

A hybrid approach based on laser texturing and surface coating for the combined modification of surface topography and chemistry has been proposed to provide a versatile approach for the development of functional surfaces. The experimental procedure comprised nanosecond pulsed laser texturing of AISI 304 stainless steel substrates followed by the deposition of thin (<1 µm) coatings with two different technologies, sol–gel deposition and PE-CVD, with the aim of independently modifying the surface topography and chemical composition. Laser texturing with different scanning strategies achieved a variety of surface morphologies with an arithmetic mean height (Sa) in the range 0.2–6.4 µm. Coatings were then deposited on laser-textured substrates to quantify the deposition effectiveness and the influence of the coating type and parameters on the resulting surface topography and chemistry. Sol–gel deposition was found to be more effective with a polymeric interlayer, improving adhesion between the coating and the textured surface; however, this also led to an increase in Sa of approximately 0.5 µm. Conversely, PE-CVD was effective in modifying the surface chemistry while inducing no measurable differences in surface morphology, effectively decoupling the texturing and coating processes. Analysis of the surface chemistry showed a higher concentration of silicon for PE-CVD than sol–gel deposition and therefore a more pronounced effect on the surface chemical composition.

Wax deposition modeling in oil-water stratified pipe flow

Wax deposition in oil-water stratified flow is commonly encountered onshore and offshore oil production pipe systems, and typically reduces transportation capacity of oil. The accurate predicted model of wax deposition has becomes an indispensable approach to design effective remediation strategies. However, a reliable mechanistic model for wax deposition prediction in oil-water two-phase stratified pipe flow is lacking to validate the deposition process. In this work, a three-dimensional (axial, radial, and angular) robust wax deposit model for oil-water stratified circular pipe flow was developed. The model of formation of a gel deposit based on the first principles of rheology was developed, associated with the results obtained from hydrodynamics and heat/mass transfer simulations. The predictions for wax deposition are found to compare satisfactorily with experimental data with two different oils for single phase and four different water cuts for oil-water stratified pipe flow. It can be seen from the wax gelation mechanism that an increase in water cut can help to reduce the wall/oil-deposit interface shear stress, thereby leading to an increase in the degree of gelation as well as the deposit rate. Furthermore, a local deposit analysis in the circumferential direction was conducted, for water cut 75% and total flow rate 5 m 3 /h, which provided insights to understand that the thickness on pipe wall was roughly uniformly distributed locates near the top of the pipe and the nearer the position gets close to two points, where the oil-water interface contacts the inner wall, the deposition thickness quickly dropped to 0. It was attributed to the fact that a roughly uniformly thickness far away from the oil-water interface contact the inner wall resulted in the slowly changes temperature along the circumferential pipe wall wetted by oil.

The effect of temperature and distance of hot airflow on the quality of MAPbCl3 thin films grown by sol–gel deposition

The effect of temperature and distance of hot airflow on the quality of MAPbCl3 thin films grown by sol–gel deposition

Polymeric solar cell with 18.06% efficiency based on poly(para-nitroaniline)/TiO2 composites

In this paper, the poly para-nitro aniline [PPNN]/titanium (IV) oxide [TiO2]NPs composite was synthesized and investigated followed by the fabrication of thin film. The sol gel and physical vapor deposition (PVD) techniques have been successfully used to deposit [PPNN/TiO2]MNC thin film with good adhesion and film thickness ≅ 100 ± 3 nm. The structural and morphological properties of [PPNN/TiO2]MNC thin films were studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). The measured optical properties of [PPNN/TiO2]MNC thin films as Reflectance (R) in the UV–vis–NIR spectrum, Absorbance (Abs), and Transmittance (T) have been employed to probe the optical characteristics at room temperatures. As well as the calculations of TD-DFT (time-dependent density functional theory) and the optimization through TD-DFT/Mol3 and Cambridge Serial Total Energy Bundle (TD-FDT/CASTEP) were employed to study the geometrical characteristics. The rectifier ration (RR), indeality factor (n) and barrier potential ΦB (eV) values are 0.74 × 105, 2.98 and 1.05 at 375 K, respectively. The Au/[PPNN/TiO2]MNC/p-Si/Al heterojunction device's power conversion efficiency are 18.06 at 200 W. cm−2. The obtained results candidates [PPNN/TiO2]MNC thin film as a good material for solar cells and optoelectronic devices.

Magnetically separable mixed metal oxide nanocomposite (Pd/MnFe2O4) for Suzuki cross-coupling in aqueous medium

Magnetically separable Pd/MnFe2O4 nanocomposite has been synthesized by coupling palladium with MnFe2O4via citrate gel auto combustion and deposition precipitation method. The physicochemical and microscopic study of Pd/MnFe2O4 was investigated using various characterization techniques. The zeta potential of the prepared nanocomposite Pd/MnFe2O4 was found to be highly negative value of -36.7 mV, which stabilizes the particle in its dispersed state and also helps to polarize the aryl-halide bond. The catalytic activity of Pd/MnFe2O4 was explored for Suzuki cross-coupling of aryl boronic acids and aryl halides (I, Cl, Br) in an aqueous medium. Interestingly, the rate of the slow oxidative addition step of the reaction is enhanced due to the high negative surface charge of the catalyst. It is worth mentioning that high turnover number (TON) and turnover frequency (TOF), thermal stability, ease of handling, nontoxic, magnetically separable, and recyclable are the remarkable properties of the present catalyst. Moreover, the protocol was found to be significant with respect to reaction time, substrate scope, the yield of products, and solvent used for the reaction.

Zirconia fixed dental prostheses fabricated by 3D gel deposition show higher fracture strength than conventionally milled counterparts

Zirconia restorations, which are fabricated by additive 3D gel deposition and do not require glazing like conventional restorations, were introduced as “self-glazed” zirconia restorations into dentistry. This in vitro investigation characterized the surface layer, microstructure and the fracture and aging behavior of “self-glazed” zirconia (Y-TZPSG) three-unit fixed dental prostheses (FDP) and compared them to conventionally CAD/CAM milled and glazed controls (Y-TZPC-FDPs). For this purpose, the FDPs were analyzed by (focused ion beam) scanning electron microscopy, laserscanning microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and a dynamic and static loading test. For the latter, half of the samples of each material group (n = 16) was subjected to 5 million cycles of thermocyclic loading (98N) in an aqueous environment in a chewing simulator. Afterwards, all FDPs were loaded to fracture. Y-TZPSG-FDPs demonstrated a comparable elemental composition but higher surface microstructural homogeneity and fracture strength compared to Y-TZPC-FDPs. Microstructural flaws within the FDPs’ surfaces were identified as fracture origins. The high fracture strength of the Y-TZPSG-FDPs was attributed to a finer-grained microstructure with fewer surface flaws compared to the Y-TZPC-FDPs which showed numerous flaws in the glaze overlayer. A decrease in fracture strength after dynamic loading from 5165N to 4507N was observed for the Y-TZPSG-FDPs, however, fracture strength remained statistically significantly above the one measured for Y-TZPC-FDPs (before chewing simulation: 1923N; after: 2041N). Within the limits of this investigation, it can therefore be concluded that Y-TZPSG appears to be stable for clinical application suggesting further investigations to prove clinical applicability.

Rheological characterization and fouling deposition behavior of coconut cream emulsion at heat processing temperature range.

Fouling deposition in the coconut cream emulsion (CCE) is considered a severe technical issue in the industry. Since the fouling deposition results from the heating effect on the CCE bulk, the heat-induced structural changes in the CCE bulk at different temperatures were rheologically investigated in the first part of this study. The second part applied different heat treatment conditions to investigate generated fouling deposition (GFD). Chemical composition, FTIR, and SEM imaging were used to explore GFDs thoroughly. The increase in viscosity and storage modulus (G') reflect such heat-induced changes over the experimental conditions. More structural changes were predicted at around ≥85°C, accompanied by a sharp increase in viscosity and (G'), which was associated with the gelation of CCE. The conformational transition, fat agglomeration in CCE bulk, generated fouling deposits (GFDs) were significant around 70°C. The chemical composition of the GFD has shown an increasing trend in the protein, carbohydrates, and ash, meanwhile fluctuation in the fat contents with increasing temperature. The FTIR peaks showed novel peaks around temperature ≥85°C, which implied new amide groups or new protein conformation. The SEM images provided the different microstructures of GFDs at high-temperature levels. More likely the GFDs appeared at temperature ≥85°C are a gel deposit layer. These findings strongly suggest that emulsion gelation was the primary cause of coconut cream fouling.

Dual response of fibroblasts viability and Porphyromonas gingivalis adhesion on nanostructured zirconia abutment surfaces.

Soft tissue integration surrounding dental implant is considered as a biological barrier against the oral microorganisms and external stimuli. At present, successful soft tissues integration around implants remains a challenge. The aim of this study was to evaluate the effects of nanostructured zirconia abutment surfaces on fibroblasts viability and Porphyromonas gingivalis adhesion, which are the two main factors influencing the quality of peri-implant soft-tissue seal. Zirconia samples were made from three-dimensional gel deposition approach and divided into three groups: zirconia surfaces, zirconia film coated surfaces (CZr) and polished surfaces (PZr). The Surface properties were characterized by scanning electron microscopy, atomic force microscopy and water contact angle. The behavior of human gingival fibroblasts (HGFs) on samples, including of proliferation, morphology, gene expression and protein expression as well as collagen synthesis were assessed. Additionally, the adhesion of P. gingivalis on samples was analyzed by scanning electron microscopy and live/dead staining. CZr and PZr group significantly enhanced fibroblasts viability such as cell proliferation, cell spreading and extracellular matrix secretion, and impaired P. gingivalis adhesion. Therefore, our findings demonstrated that CZr and PZr surfaces with nano-grains or grinding grooves might be considered as the feasible zirconia abutments substrate for reinforcing HGFs response and minimizing P. gingivalis adhesion, and thereby enhance peri-implant soft-tissue integration.

Biocontrol Aspergillus species together with plant biomass alter histochemical characteristics in diseased mungbean plants.

In the present study, two Aspergillus species as biocontrol agents together with Chenopodium quinoa dry biomass were used to investigate their effects on histochemical features of mungbean plant inoculated with M.phaseolina. In a pot experiment, Aspergillus flavipes and Aspergillus versicolor were added either alone or together with 1%, 2%, and 3% dry biomass of quinoa (DBQ) to the pot soil already inoculated with M.phaseolina. After 4 weeks of sowing, root and lower-stem sections of the mungbean plants were stained with ferric chloride, phloroglucinol-HCl and Lugol's iodine to detect the presence of polyphenols, lignin, and starch granules, respectively, and observed under light microscope. Stem and root sections were also observed under scanning electron microscope (SEM) to reveal the effect of soil amendments on cell structures. The findings revealed that mungbean plant cross sections from all the treatments except positive control (only inoculated with M.phaseolina) showed very clear cell structures. In positive control, distorted, fragmented, and collapsed cell structures were observed. Moreover, M.phaseolina blocked vascular vessels in comparison to negative control where the cell structures were intact and normal in size. Plant sections from treatments with A.flavipes and A.versicolor alone or together with DBQ were without pathogen colonization, with normal cell structures and a high deposition of gel. The results suggested that the two Aspergillus spp. and C.quinoa induced defense responses in mungbean plants. HIGHLIGHTS: Macrophomina phaseolina causes significant yield losses in mungbean. Pot soil was amended with two species of Aspergillus as biocontrol agents along with plant biomass. Aspergillus spp. markedly saved the root and stem structures from the damage caused by M.phaseolina.

Histopathological changes in root and stem of mungbean exposed to Macrophomina phaseolina and dry biomass of Chenopodium quinoa.

Mungbean production is affected by a fungal pathogen Macrophomina phaseolina. A pot experiment was carried out to check the effect of quinoa (Chenopodium quinoa Willd.) dry biomass on the histopathological features of mungbean exposed to M. phaseolina. For this, 1%, 2% and 3% (wt/wt) of C. quinoa dry biomass was mixed in the soil inoculated with M. phaseolina. The highest disease incidence (36%) was recorded in the positive control (only M. phaseolina). Different treatments of quinoa dry mass reduced disease incidence to 4-7%. After 4 weeks of germination, stem and root sections were stained in phloroglucinol-HCl, ferric chloride and Lugol's iodine stains for the detection of lignin, polyphenols and starch granules, respectively, and studied under light microscope. Plants of positive control showed damaged cells, and heavy deposition of lignin, phenolics and starch granules as compared to plants of the negative control and those grown in the soil amended with different doses of dry biomass of quinoa. For better understanding, plant root and stem sections were studied under a scanning electron microscope. Plant sections from positive control exhibited the presence of M. phaseolina sclerotial bodies and hyphal growth, whereas in negative control normal cell structures were observed. However, C. quinoa amended stem and root sections revealed the presence of high gel deposition with normal cell structures and no pathogen establishment. This study concludes that application of C. quinoa is an effective and natural remedy to activate the resistance mechanism in plants and to combat the adverse effects of M. phaseolina. HIGHLIGHTS: Macrophomina phaseolina causes charcoal rot in mungbean. Chenopodium quinoa amendment significantly reduced incidence of charcoal rot disease. M. phaeolina increased concentrations of polyphenols, lignin and starch granules in mungbean.

Structural, electrical and photoluminescence properties of ZTO thin films for water depollution

The degradation of an azo dye Amido Black 10B in aqueous solution by photo-catalytic reaction with an optimized ZnO-SnO2 (ZTO) thin film has been investigated. Optimization of structural, electrical and photoluminescence properties of ZTO films was carried out by varying the molar ratio (ZnO:SnO2) from (1:1) to (4:1) during the chemical sol–gel deposition. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Hall Effect measurements, UV–Visible analyzes, and photoluminescence spectroscopy (PL). SEM analyzes confirm the synthesis of ZTO layers and indicate that the morphology of the obtained ZTO layers change by increasing the molar ratio. XRD shows a slight increase in the crystalline nature of ZnO and a small decline in that of SnO2 by increasing the concentration of ZnO. The results of Hall effect measurements, photoluminescence spectroscopy and UV–Vis analyzes suggest that the optimized addition of the ZnO improve light absorption especially in the short wavelength range and participate in radiative recombination under photo-excitation. Evolution of the photo-catalytic activity revealed that the optimized ZTO thin film exhibited an improved photo-catalytic performance in the degradation of Amido Black 10B under UV irradiation. Around 70.46% of the degradation of this azo dye was achieved within 240 min. These results suggest that prepared ZTO with molar ratio of (2:1) is promising candidate for photo-catalytic application.

Progress in Niobium Oxide-Containing Coatings for Biomedical Applications: A Critical Review.

Typically, pure niobium oxide coatings are deposited on metallic substrates, such as commercially pure Ti, Ti6Al4 V alloys, stainless steels, niobium, TiNb alloy, and Mg alloys using techniques such as sputter deposition, sol–gel deposition, anodizing, and wet plasma electrolytic oxidation. The relative advantages and limitations of these coating techniques are considered, with particular emphasis on biomedical applications. The properties of a wide range of pure and modified niobium oxide coatings are illustrated, including their thickness, morphology, microstructure, elemental composition, phase composition, surface roughness and hardness. The corrosion resistance, tribological characteristics and cell viability/proliferation of the coatings are illustrated using data from electrochemical, wear resistance and biological cell culture measurements. Critical R&D needs for the development of improved future niobium oxide coatings, in the laboratory and in practice, are highlighted.

Surgical treatment of experimental peri-implantitis using mechanical and chemical decontamination procedures: A pre-clinical in vivo study.

To evaluate the effect of surgical treatment of experimental peri-implantitis at implants with different surface characteristics using mechanical and chemical decontamination methods. Following extraction of mandibular premolars, four implants with two different surface characteristics (A, moderately rough and B, smooth) were placed in each side of the mandible of six dogs. Experimental peri-implantitis was induced. Surgical treatment of the peri-implantitis sites was carried out using four implant surface decontamination protocols: (i) deposition of a citric acid gel, (ii) mechanical cleaning using a rotating titanium brush, (iii) a combination of the mechanical and chemical procedures, and (iv) saline (control). Clinical and radiographic examinations were performed. Block biopsies were obtained 6months after therapy and prepared for histological analysis. Irrespective of the treatment group, treatment resulted in 0.63 ± 0.92 and 0.65 ± 0.67 mm radiographic bone gain around implants A and B, respectively. Histological analyses revealed that persisting soft tissue inflammation as assessed using an infiltrated connective tissue (ICT) score was significantly lower at implant type B than at implant type A for all treatment groups. The test decontamination procedures did not demonstrate better results regarding resolution of peri-implantitis lesions, as indicated by the ICT scores, than the control procedure. The control treatment resulted in significantly superior outcomes of resolution of peri-implantitis lesions than the citric acid regimen. It is concluded that decontamination procedures including citric acid gel or rotating titanium brush did not improve outcomes following surgical treatment of experimental peri-implantitis. Results were, however, influenced by the implant surface characteristics.

Adaptation and uniformity of monolithic zirconia crowns fabricated by additive 3-dimensional gel deposition

Statement of problemA novel monolithic zirconia restoration fabricated by additive 3-dimensional (3D) gel deposition, named as self-glazed zirconia (SGZ), has recently been developed. SGZ crowns exhibit reliable mechanical properties and esthetic appearance, but their adaptation and uniformity are unclear. PurposeThe purpose of this in vitro study was to compare the adaptation and uniformity of monolithic zirconia crowns fabricated by additive 3D gel deposition with that of milled zirconia and lithium disilicate crowns. Material and methodsTen identical resin abutments were made based on the scanning data of an extracted and prepared human mandibular first molar. Three types of monolithic crowns were then fabricated by using 2 different processes: 3D gel deposition zirconia (SGZ), milled zirconia (ZZ), and milled lithium disilicate (EMX) (n=10) through a completely digital workflow. The nondestructive direct-view technique and replica technique were used to measure the marginal and internal discrepancy values individually. The uniformity index was calculated to describe the uniformity of the internal space. The results were analyzed by using 1-way ANOVA and Kruskal-Wallis statistical tests (α=.05). ResultsThe marginal discrepancy of EMX exhibited the highest values among the 3 groups (P=.001). The 2 types of zirconia crowns had comparable marginal discrepancy values (P>.05). The internal discrepancy values of SGZ were significantly lower than those of EMX at the occlusal region and of ZZ at all measured locations (P<.05). All 3 types of monolithic crowns showed comparable good uniformity (P=.056). ConclusionsThe marginal and internal adaptations of novel monolithic zirconia crowns were within clinical requirements. Compared with the zirconia and lithium disilicate crowns fabricated by subtractive milling, monolithic zirconia crowns fabricated by additive 3D gel deposition had comparable uniformity and better internal adaptation.

Mechanical Stability Is Key for Large-Scale Implementation of Photocatalytic Surface-Attached Film Technologies in Water Treatment

Replacement of classical tertiary water treatment by chemical-free sunlight-driven photocatalytic units has been often proposed. Photocatalysts are required to be cost-effective, inert, chemically stable, reusable, and easy to separate and also that they are mechanically stable. The effect of mechanical stress on a photoactive TiO2 layer, and on its effectivity for degradation of phenol as a model pollutant, has been studied during photocatalytic water treatment using NUV–vis light. Sol–gel (SG) and liquid phase deposition (LPD) methods have been used to coat spherical glass beads with the photocatalyst (TiO2). Physicochemical characterization of coated glass beads has been performed by N2 adsorption–desorption isotherms, SEM, EDXS, and AFM. Phenol photocatalyzed degradation was carried out both in stirred batch and flow reactors irradiated with a medium-pressure Hg-vapor lamp (λ &amp;gt; 350 nm). Phenol concentration was determined by HPLC, and its photoproducts were identified using HPLC/MS. In the stirred batch reactor, all LPD-coated glass beads displayed higher catalytic activity than SG-coated ones, which increased with calcination temperature, 700°C being the most efficient temperature. Preliminary etching of the glass beads surface yielded dissimilar results; whereas, phenol photodegradation with SG-coated etched glass beads is twice faster than with unetched SG ones, the rate reduces to one-third using LPD etched instead of unetched LPD glass beads. Phenol photodegradation using LPD is similar both in stirred batch and flow reactors, despite the latter uses a lower catalyst load. LPD-etched catalyst was recovered and reused in the stirred batch reactor; its activity reduced sharply after the first use, and it also lost activity in successive runs, ca. 10% of activity after each “use and recover” cycle. In the flow reactor, activity loss after the first experiment and recycling (ca. 30%) was much larger than in the following runs, where the activity remained rather constant through several cycles. LPD is more adequate than SG for TiO2 immobilization onto glass beads, and their calcination at 700°C leads to relatively strong and reactive photocatalytic films. Still, TiO2-coated glass beads exhibited very low photoactivity compared to TiO2-P25 nanoparticles, though their separation is much easier and almost costless. The durability of the catalytic layer increases when using a flow reactor, with the pollutant solution flowing in a laminar regime through the photocatalyst bed. In this way, the abrasion of the photocatalytic surface is largely reduced and its photoactivity is better maintained.

Knife-edged crown fabricated by 3-dimensional gel deposition and soft milling

Statement of problemRestorations with knife-edge margins are more prone to margin chipping during the manufacturing process. Three-dimensional gel deposition shows potential for fabricating zirconia restorations with good margin quality, but studies on its performance in fabricating knife-edged crowns are lacking. PurposeThe purpose of this in vitro study was to compare the 3-dimensional trueness, surface morphology, and margin quality of self-glazed zirconia and soft-milled zirconia crowns with knife-edge margins. Material and methodsAn abutment with a knife-edge finish line design was prepared and scanned with a laboratory scanner. Anatomic contour crowns were designed and fabricated by 3-dimensional gel deposition and soft milling (n=5). The crowns were digitalized, and the scan data were superimposed on the computer-aided design (CAD) data for 3-dimensional deviation analysis. Surface morphology and margin quality were characterized with microscopic examination. ResultsThe self-glazed zirconia crowns showed a smooth and glossy appearance. The soft-milled crowns showed traces left by the removal of support bars and numerous micropits of various sizes. In internal areas, no significant difference was found in root mean square values between the 2 groups (P＞.05). For the external surface, self-glazed zirconia showed statistically lower root mean square values than the soft-milled crowns (P＜.05). When observed at ×5 magnification, all the self-glazed zirconia crowns showed smooth edges with no defects, whereas small or large margin defects were found in the soft-milled crowns. When characterized at ×200 magnification, minor margin flaws were observed in the self-glazed zirconia crowns. More and larger margin defects were found in the soft-milled crowns. ConclusionsThree-dimensional gel deposition forms a smoother and more homogeneous surface than soft milling. Knife-edged self-glazed zirconia crowns have good dimensional accuracy and margin quality.

A nanotubular TiO2/SiOx/Si composite derived from cellulosic cotton as an anode material for lithium-ion batteries with enhanced electrochemical performance

A TiO2/SiOx/Si composite derived from cellulosic cotton as the structural template was biomimetically synthesized. Modified sol–gel deposition processes were performed to coat each cellulose nanofiber with a SiO2 thin gel layer, followed by layer-by-layer self-assembly processes to form an external TiO2 coating with controllable thickness. The resulted matter was calcined in air to obtain the TiO2/SiO2 composite, which was successively put in N2 atmosphere and treated with magnesiothermic reduction reaction, resulting in the final TiO2/SiOx/Si composite. The composite possessed a typical hierarchical three-dimensional (3D) nanotubular network microstructure precisely inherited from the cellulosic cotton template, and each nanotube had a core-shell nanostructure with Si-based matters as the core and TiO2 coating as the shell. Compared with the bare nanotubular SiOx/Si material, the TiO2/SiOx/Si composite showed a highly enhanced electrochemical performance as an anode material for lithium-ion batteries (LIBs), delivering an initial discharge capacity of 2370 mAh g−1 at a current density of 0.2 A g−1 (an initial Coulombic efficiency of 56.4%), a reversible capacity of 682 mAh g−1 after 100 discharge/charge cycles, and a discharge capacity of 241 mAh g−1 at a high current density of 2.0 A g−1. The excellent specific capacity, cycling stability and rate capability are ascribed to the synergistic effect of the unique 3D porous nanotubular network structure and the uniform TiO2 coating layer, which accommodates the volume variation of Si-based components during cycling, offers sufficient ion transport pathways and improves the electron transfer efficiency. This work provides a facile biomass-based strategy for fabrication of metal oxide/Si composites with well-defined microstructures that exhibit significant potential as anode materials for LIBs.

Optimization of the production process of BZT–BCT sol–gel thin films obtained from a highly stable and green precursor solution

ABSTRACT Barium Zirconate Titanate–Barium Calcium Titanate (BZT–BCT) is an environmentally friendly piezoelectric-ferroelectric ceramic that is a promising alternative to lead zirconate titanate (PZT), whose toxicity is well known. Producing thin films by sol–gel deposition with properties comparable to their bulk counterparts is quite a difficult task, because of the substrate constraints which typically generate residual stresses during the production process, leading to the onset of cracks. Moreover, typically employed solutions contain toxic and harmful substances or are unstable over time. Recently, we produced a highly stable BZT–BCT precursor solution based on nontoxic and non-carcinogenic solvents. In this work, we optimized the BZT–BCT sol–gel deposition process by varying the spin coating velocity, which influences the thickness of each deposited layer, and the pyrolysis temperature, which impacts on the formation of cracks. Moreover, we explored the possibility to add a third heat treatment step to the deposition process with the aim of releasing the residual stresses, further improving the film properties. As a result, 250 nm thick films were obtained with optimized morphology and limited presence of cracks, thus enhancing the ferroelectric properties (Pr = 33.26 μC cm−2, Ec = 220.6 kV cm−1, ε = 1817).

Protein Content of Model Synovial Fluid and CoCrMo Wear

Wear of cobalt chromium molybdenum alloy in a reciprocating ball-on-plate test was measured for a series of model synovial fluid samples, where the effect of protein and phospholipid content was examined. The protein content (albumin and γ-globulin) was varied to replicate a range of healthy and diseased SF pathologies. The results showed reduced wear was strongly correlated with increasing protein content. The effect of phospholipid addition on wear was more complex. Limited evidence suggested phospholipids reduced wear for a high albumin/γ-globulin ratio (A/G) but increased wear for low A/G ratios. Post-test examination showed thick (~μm) insoluble “gel-like” films were deposited in, and around, the wear scar. Micro Infrared Reflection Absorption Spectroscopy analysis indicated the films were predominately denatured β-sheet proteins although in some cases lipids were also present. Similar films were found in tests with human synovial fluid samples. Scanning Electron Microscopy imaging showed an aggregated fibril “rope” structure typical of non-native β-sheet proteins. The gel film is a protein-rich viscous phase which is entrained intermittently to form a lubrication film which contributes to surface protection and reduction of wear. We also suggest the formation of gel deposits is comparable to the “boosted” lubrication model of proposed by Professor Duncan Dowson for articular cartilage. In the boosted model high-viscosity, concentrated protein films are formed in depressions on the cartilage surface. The tests indicate the chemistry of human synovial fluid, particularly the protein content, could affect CoCrMo wear and therefore the risk of implant failure.