Incorporation Of Silicon Research Articles

Silicon-Substituted Hydroxyapatite Particles and Response of Adipose Stem Cells In Vitro

Due to the similarity of synthetic hydroxyapatite (HA) to natural bone tissue, but, because of its low degradation rate, the current study focuses on silicon-substituted HA (Si-HA) synthesis, characterization, and biological evaluations. Si-HA was successfully prepared through sol-gel processing route and characterized using SEM, EDX, XRD, and FTIR. Si-HA particles were found to be non-cytotoxic following exposure to adipose stem cells (ADSCs). In fact, Si-HA particles showed a high level of matrix mineralization following prolonged and continuous exposure to ADSCs. It is suggested that the incorporation of Si in HA structure positively affects cellular behavior, associated with a higher degradation rate, and subsequently greater level of ionic product release from Si-HA particles. Hydroxyapatite (HA) has long been applied as bone substitutes but its low degradation rate limits its application. One approach is the incorporation of silicon (Si) within HA structure. This study confirms that Si-substituted HA enhance stem cell proliferation and promote osteogenic differentiation. Hence, Si-HA could be utilized in composites, scaffolds, and coatings for bone-related disorders.

Multi-targeted anti-leukemic drug design with the incorporation of silicon into Nelarabine: How silicon increases bioactivity

Acute Lymphoblastic Leukemia (ALL) represents 30% of all childhood cancers and children younger than 5 years old have the highest risk for developing ALL. Existing ALL drugs do not respond in approximately 20% of treatment. Therefore, drug development studies against ALL must be continued with either developing existing drugs or discovering new ones. In this study, we evaluated the U.S Food and Drug Administration (FDA) approved ALL drugs according to their physicochemical and pharmaceutical properties, and Nelarabine was found to have the highest bioactivity score. Using the key strategy of bioisosterism commonly accepted by medicinal chemists, we investigated in silico ADME properties, drug-likeness, and biological activity of new designed twenty-four compounds including Nelarabine. The results were evaluated in terms of two classifications: broad spectrum biological activity and filtering of five different drug likeness criteria of the literature including Lipinski's rule of five. We interestingly observed that silicon incorporated compounds exhibited better performance on both criteria by targeting broader spectrum of drug receptors including G-protein coupled receptor (GPCR), ion channel modulator, kinase inhibitor, protease and enzyme inhibitor and by satisfying all of five different drug-likeness criteria reported in the literature. Design compound C19 appeared as a potential drug candidate for further pharmacological research.

Expanding the Chemical Space of Withaferin A by Incorporating Silicon To Improve Its Clinical Potential on Human Ovarian Carcinoma Cells.

Ovarian cancer represents the seventh most commonly diagnosed cancer worldwide. Herein, we report on the development of a withaferin A (WA)-silyl ether library with 30 analogues reported for the first time. Cytotoxicity assays on human epithelial ovarian carcinoma cisplatin-sensitive and -resistant cell lines identified eight analogues displaying nanomolar potency (IC50 ranging from 1 to 32 nM), higher than that of the lead compound and reference drug. This cytotoxic potency is also coupled with a good selectivity index on a nontumoral cell line. Cell cycle analysis of two potent analogues revealed cell death by apoptosis without indication of cell cycle arrest in G0/G1 phase. The structure-activity relationship and in silico absorption, distribution, metabolism, and excretion studies demonstrated that the incorporation of silicon and a carbonyl group at C-4 in the WA framework enhances potency, selectivity, and drug likeness. These findings reveal analogues 22, 23, and 25 as potential candidates for clinical translation in patients with relapsed ovarian cancer.

Research on Connection between Essential Properties and Micromechanism of Organic Silicon–Modified Cement Mortar

Abstract This article aimed to research the effect of organic silicon on the density, mechanical strength, water absorption, porosity, and crack resistance of cementitious construction materials. Modified cement mortar was prepared by adding different amounts of organic silicon into control cement mortar. Mechanical strength was evaluated using bending and compressive strength tests. Porosity was evaluated to assess the inner structure of cement mortar. Furthermore, the micromechanism of modified cement mortar and control cement mortar was explored using the nitrogen-absorption test and a Scanning Electron Microscope (SEM). Experimental results showed that for the organic silicon and mix design used in this article, the incorporation of organic silicon generally reduced the mechanical strength and density and increased the water absorption, porosity, and crack resistance. In addition, the analysis of the nitrogen-absorption test and SEM test revealed the modified mechanism and the connection between the macroscopic properties and micromechanism of modified cement mortar.

Improved Interface Properties and Dielectric Breakdown in Recessed AlGaN/GaN MOS-HEMTs Using HfSiO<inline-formula> <tex-math notation="LaTeX">$_{{x}}$ </tex-math> </inline-formula> as Gate Dielectric

In this letter, we report optimized transport properties in gate recessed enhancement-mode GaN MOS-HEMTs by incorporating silicon into atomic layer deposited gate dielectric HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Compared with commonly used HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gate dielectric, the interface trap density can be reduced by nearly an order of magnitude and the fixed oxide traps inside are reduced to almost half using the high-quality passivation of HfSiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> . The MOS-HEMTs based on HfSiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> exhibit a threshold voltage of 1.5 V, excellent subthreshold swing of 65 mV/dec, and a high on-off ratio of 3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> . The incorporation of silicon in HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> can also increase the dielectric breakdown property with maximum gate electric field of 2.85 MV/cm for a 10-year time-dependent gate dielectric breakdown lifetime, which is 36% higher than pure HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . The maximum breakdown voltage of HfSiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> MOS-HEMT is 742 V, which is 30% higher than HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> MOS-HEMT.

Improvement of mechanical, humidity resistance and thermal properties of heat-treated rubber wood by impregnation of SiO2 precursor

The SiO2 precursor solution was impregnated into heat-treated rubber wood to enhance its mechanical and flame-retarding properties. Test specimens were randomly divided into four groups, i.e., untreated (U), heat-treated (HT), impregnated SiO2 precursor before heat treatment (ISB) and after heat treatment (ISA). Results showed that, compared with HT wood specimens, the modulus of rupture (MOR) and compression strength of ISB and ISA wood specimens were both increased. The hygroscopicity of modified wood was decreased and the dimension stability was consequently improved. Surprisingly, the hardness of ISB specimens increased by 43.65%. The thermogravimetric (TG) examination showed that the incorporation of silicon retarded the thermal decomposition and improved the thermal stability of wood. Furthermore, the scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDXA) revealed that the SiO2 gel was deposited in the cell wall, The Fourier transform infrared spectroscopy (FTIR) showed the formation of Si–O–Si and Si–O–C covalent bonds. The X-ray diffraction (XRD) tests indicated that the impregnation of SiO2 precursor had slight effect on the crystalline structure of the wood.

Optimization Conditions for Crystal Growth of Novel Nanolayers, Nanohybrids and Nanocomposites Based on Cobalt, Zirconium, Titanium and Silicon

AbstractThe present study has a triple aim for producing three novel nanostructures through incorporation of zirconium, titanium and silicon in the host layer of layered double hydroxides (LDH) beside cobalt. These four metals were designed in ordered structures for creating novel nanolayers inside LDH. By modifying these nanolayers with fatty acid, another novel nanohybrid material was produced. This nanohybrid contains 38% of inorganic species in addition to 62% of hydrocarbons fatty acid. In addition, the thermal treatment of the nanolayered structure converted the nanolayers of Co‐Si‐Zr‐Ti LDH to nanocomposites consisting of nanoparticles of cobalt oxide doped by triple dopants in an order manner: zirconium titanium and silicon. The crystals growth of Co‐Si‐Ti‐Zr LDH was studied from 9 h to 32 h through four stages. These stages were followed by different techniques. Finally, this study concluded that the nanolayered structure of Co‐Si‐Zr‐Ti, which is not yet published in the literature, could be formed with well‐crystallized phase. This novel 2D nanomaterial has positive impact to open the way for creating novel nanocomposites and nanohybrids.

Nanostructuring Strategies To Increase the Photoelectrochemical Water Splitting Activity of Silicon Photocathodes

Photoelectrochemical water splitting is a promising route for sustainable hydrogen production. Herein, we demonstrate a photoelectrode motif that enables a nanostructured large-surface area electrocatalyst without requiring a nanostructured semiconductor surface with the goal of promoting electrocatalysis while minimizing surface recombination. We compare the photoelectrochemical H2 evolution activity of two silicon photocathode nanostructuring strategies: (1) direct nanostructuring of the silicon surface and (2) incorporation of nanostructured zinc oxide to increase the electrocatalyst surface area on planar silicon. We observed that silicon photocathodes that utilized nanostructured ZnO supports outperformed nanostructured silicon electrodes by ∼50 mV at open circuit under 1 sun illumination and demonstrated comparable electrocatalytic activity.

Incorporation of silicon into strontium modified calcium phosphate bone cements promotes osteoclastogenesis of human peripheral mononuclear blood cells

Given the important effects of strontium and silicon on cells of the bone as well as the increasing incidence of osteoporotic fractures, calcium phosphate-based bone cements containing silicon and strontium might represent a promising tool for bone replacement therapies of systemically altered bone. However, information about combined effects of strontium and silicon on osteoclastogenesis is still not available. Therefore, differentiation capacity of human peripheral blood mononuclear cells into osteoclast-like cells was investigated by culturing the cells in combination with a strontium- (pS100) and a strontium/silicon-modified calcium phosphate bone cement (pS100-G). Following culturing expression patterns of the cells in respect of their differentiation- and fusion-capacity were determined by real-time quantitative polymerase chain reaction, while cell morphology was visualized by phalloidin staining of the actin cytoskeleton. Additionally, strontium and silicon release from the bone cements into the cultivation media was determined using inductively coupled plasma mass spectrometry while surface topography of the cements was investigated by scanning electron microscopy. The results show that simultaneous incorporation of strontium and silicon into calcium phosphate cements changes properties of the cement such as solubility, and nearly abrogates the inhibitory effects of strontium on osteoclastogenesis.

Effects of Fluorine and Silicon Incorporation on Tribological Performance of Diamond-Like Carbon Films

Diamond-like carbon (DLC) is a metastable amorphous film that exhibits unique properties. However, a number of limitations exist regarding the use of DLC, for instance, its tribological characteristics. In this article, the fluorine and silicon incorporated diamond-like carbon (F-DLC and Si-DLC) films are studied, taking into account the tribological properties of these films compared with pure DLC. The structures of the films were characterized using Auger electron spectroscopy and Raman spectroscopy. The hardness and elastic modulus were evaluated by nanoindentation hardness testing. The friction behavior was assessed using ball-on-disk friction testing and optical microscopy. The results indicated that the deposited DLC films contained 0.6 - 2.1 at.% F and 26.7 - 38.4 at.% Si. A decrease in the hardness and elastic modulus was obtained as F increased in content, which was the opposite of the behavior observed in the Si-DLC films. This was due to the shifting in the G-peak position, which is related to the sp3 bonding fraction in the film. When measured in ambient air, the addition of Si into the DLC film strongly influenced the friction coefficient, whereas doping with F only slightly influenced the films, as evidenced by their wear scars. In addition, only a 26.7 at.% Si-DLC film showed a very low friction coefficient when measured in dry air. This was attributed to the formation of silicon-rich transfer layer on the ball surfaces. Therefore, the addition of Si with 26.7 at.% content to a DLC film can be considered beneficial for improving tribological performance.

Removal of Sulphides and Benzene in Fluid Catalytic Cracking Gasoline by Insitu Hydrogenation Over NbFAPSO-5

Niobium containing aluminophosphate molecular sieve (NbFAPSO-5) was hydrothermally synthesized with AlPO-5 type structure. Characterization of this catalyst was performed by X-ray diffraction to determine its structure, inductive coupled plasma-atomic emission spectrometry (ICP-AES) for its elemental composition and infrared spectrometry (IR) to access its acidic properties. X-ray diffraction patterns confirmed well AlPO-5 type structure. ICP-AES analysis confirmed the incorporation of silicon (12.9%), aluminium (15.4%), phosphorous (21.9%), iron (5.62%) and niobium (0.39%) into AlPO-5 framework. Infrared spectrometry analysis showed that both Bronsted and Lewis sites were found in the synthesized sample. A fixed-bed reactor was used to investigate the activity of the resulting catalysts in the removal of sulfides and benzene in fluid catalytic cracking gasoline. Under suitable conditions of a metal loading of 15%, a reaction temperature of 423K, a reaction time of 30 min, a space velocity of 3 h^-1, and a reaction pressure of 1 MPa; desulfurization and debenzolization ratios reach 100% and 19.9% respectively. Research octane number of the gasoline increased by two units. This remarkable behavior makes NbFAPSO-5 family, a potential candidate for industrial application as catalysts in the clean fuel.

Effect of Synthesis Temperature Formation of the Structure and Properties of Silicoaluminophosphate with the AEI Structure

Changes in the phase, morphological, and textural properties of silicoaluminophosphates with the AEI structure during crystallization at 150, 170, and 190°С are studied. Using a combination of physicochemical methods, evolution of the solid phase extracted at different steps of synthesis is shown. It is established that at 150°С the microporous phase containing silicon in tetrahedral positions of the framework appears already at the initial stages of crystallization and further nanostructuring of the solid phase is associated with the incorporation of silicon via the SM3 mechanism. At 170°С, crystallization proceeds through formation of the aluminophosphate and aluminosilicate mixed mesoporous composite. The transformation of mixed composite into the microporous crystalline material is accompanied by the incorporation of [SiO4] isolated tetrahedra into the forming crystalline framework according to the SM2 mechanism; this provides a strong acidity of the material. The intermediate mesoporous semiproduct extracted at the initial stages of synthesis at 190°С is a mixture of disordered aluminophosphate and coarse mesoporous agglomerates; their transformation into silicoaluminophosphate with the AEI structure occurs only upon silica transfer to the liquid phase, and the incorporation of silicon into the AEI crystalline framework proceeds via the SM3 mechanism with the subsequent formation of silicon islands.

Effect of silicon incorporation method in the supports of NiMo catalysts for hydrotreating reactions

NiMo catalysts supported on Al–Si supports with 5 wt% Si were prepared by two methods: 1) by incorporating Si into boehmite, followed by drying and calcination producing the catalyst NiMo/Si-Al and 2) by incorporating Si into the surface of an already calcined alumina producing NiMo/Si/Al. These two methods of Si incorporation into the alumina produced different surface structures of the Si oxide overlayer and affected the performance of the supported active Ni–Mo–S phase during the processing of partially hydrotreated Maya crude oil and during cumene hydrocracking, which is used as a model reaction to analyze the acidity function of the catalysts. The purpose of using partially hydrotreated Maya crude oil as feedstock is to test the catalysts in the hydrodesulfurization (HDS) of highly refractory sulfur compounds, such as 4,6-dimethyldibenzothiophene. The supports and catalysts (fresh and spent) are analyzed using nitrogen physisorption, X-ray diffraction, scanning electron microscopy–energy dispersive spectroscopy, and Fourier-transform infrared spectroscopy of surface hydroxyl groups. Depending on the method employed to incorporate Si into the support, the catalyst properties are affected, resulting in higher conversion in hydrotreating (HDT) reactions. The catalysts with Si incorporated into boehmite display the highest activity in the HDT of refractory compounds present in Maya HDT/Diesel HDS (50/50 vol%) feedstock, which is the result of higher dispersion of the active phase, combined with adequate porosity and acidity.

Influence of quartz on silicon incorporation in HVPE grown AlN

Aluminum nitride growth via hydride vapor phase epitaxy has been investigated with respect to impurity uptake. The precursor aluminum chloride was identified to react with quartz glass and provide silicon into the reactor atmosphere and subsequently into grown AlN layers. Reactor parts made of quartz were consecutively replaced by carbon glass parts to prevent unintentional silicon incorporation into III-nitride layers during growth. Carbon glass substitution of quartz parts led to a reduction of silicon levels in AlN by three orders of magnitude to 4*1016 cm−3, while carbon concentration in grown AlN layers remained low in the range of 1017 cm−3.

Understanding the corrosion and tribological behaviors of CrSiN coatings with various Si contents in HCl solution

Abstract CrSiN coatings with various Si contents were prepared on 304L substrate through medium frequency magnetron sputtering. Toughness, corrosion resistance and tribology property of as-prepared coatings in 0.1 M HCl solution were studied. The result showed that the toughness of CrN coating was effectively enhanced by the incorporation of proper silicon. Compared with other coatings, the CrSiN coating with high silicon proportion presented lower icorr and higher |Z|0.01 Hz. When the silicon proportion exceeded 16.0 at.%, the inhibition efficiency was up to 99.10%. During tribology test, the COF and wear rate descended at the early stage and then ascended as the silicon proportion increased as a whole, which was ascribed to the combined action between toughness, anti-corrosion and lubrication behaviors.

The study of PEO coated zirconium doped aluminum composites

Powder aluminum composites without additives and doped with 0.2, 0.5, and 1 % Zr were obtained using the cold pressing and sintering in vacuum. The composites were investigated using scanning electron microscopy (SEM) and synchronous thermal analysis. It was found that with an increase in the zirconium content, the melting point of aluminum composites slightly rises. On the surfaces of aluminum composites samples oxide coatings with a thickness up to 50 μm were formed by plasma electrolytic oxidation (PEO). It was found that the coatings have a two-layer structure. The addition of 1 % Zr to the aluminum composite more than doubles decrease the incorporation of silicon from the electrolyte into the near-surface layer of the PEO coating.

Form-stable phase change materials with enhanced thermal stability and fire resistance via the incorporation of phosphorus and silicon

In this paper, a series of novel form-stable phase change materials (PCMs) containing phosphorus and silica were prepared by transesterification of diethyl phosphite with 1-tetradecanol, 1-hexadecanol and 1-octadecanol, followed by ring-opening reaction and hydrolytic condensation of 2,3-epoxypropoxy propyltrimethoxysilane (silane coupler KH-560). The leakage of pure higher alcohols in molten state was effectively solved due to the support of cross-linked silicon network structure. The co-incorporated phosphorus and silicon would accelerate the formation of chars and improve the thermal stability and fire resistance. The chemical structure and crystalline structure of form-stable PCMs were determined by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Differential scanning calorimeter (DSC) results indicate the melting points are in the range of 29 °C to 55 °C with the latent heat between 81.5 J/g to 116.9 J/g. Thermogravimetric (TG) analyses exhibit improved thermal stability of prepared PCMs compared to pure higher alcohols. The results of scanning electronic microscope (SEM), energy dispersive spectroscope (EDS) and FT-IR confirm the formation of phosphorus-rich and silicon-rich compact chars after thermal treatments.

Synthesis of low shrinkage monolith alumina aerogels by surface modification and ambient pressure drying

The authors have synthesised a kind of low shrinkage alumina (Al2O3) aerogel using an inexpensive salt of aluminium (AlCl3 ·6H2 O) via tetraethoxysilane modification and an ambient pressure drying process. The morphology, pore structure, surface group, crystal phase and thermal properties of the Al2O3 aerogel are analysed by X-ray diffractometer, scanning electron microscopy, Fourier transform infrared spectra and nitrogen adsorption test. Further improvement in thermal stability and thermal shrinkage are obtained by incorporation of silicon (Si) atoms during the aerogel preparation. The specific surface area of modified aerogel is 480 m2/g and the diameter shrinkage is 8% after drying, and reach 304 m2/g and 16.5% after heating at 1000°C. The approach, which is straightforward, inexpensive and safe, can be employed to prepare a monolithic mesoporous material with low shrinkage and high-temperature resistance. This will further promote the potential application of packaging and thermal insulation materials.

Bionic boron/silicon‐modified phenolic resin system with multifunctional groups: synthesis, thermal properties and ablation mechanism

A kind of silicon-and-boron-modified phenolic–formaldehyde resin (SBPF) with excellent thermal stability was fabricated via a simple two-step method and used for the matrix of ablation materials. The structure and thermal stability of the modified phenolic–formaldehyde resins (PFs) were characterised. The results showed that boron and silicon elements have been incorporated into SBPF in the form of a chemical bond. Meanwhile, the cured products showed an increase in graphite structure and a decrease in disordered structure due to the incorporation of boron and silicon. Compared with the ordinary phenolic resin, the initial thermal degradation temperature and charring yield at 800°C of SBPF increased by 73°C and 15 wt%, respectively. Further, the modified PFs, nano-Al2O3 powders, glass powders and vitreous silica fibres were used to obtain a novel ceramizable phenolic moulding composite. The morphology, chemical composition and ablative characteristics of the composites were explored. The results showed that a compact and homogeneous SiO2–Al2O3 layer formed on the ablated surface and protected the carbonised matrix and fibres from further oxidation. Compared with the ordinary PF composites, the SBPF composites showed a highly decreased linear/mass ablation rates, indicating the synergistic effect of boron and silicon modification on the enhanced ablation property.

Theoretical analysis of the kinetics of precipitation of lizardite and magnesite from olivine alteration

The present theoretical study analyzes the kinetic characteristics of precipitation of magnesite and lizardite as a result of hydrothermal alteration of olivine under high carbonate alkalinity. It makes use of a simulation strategy in which, both the chemical evolution of the aqueous solution and the solid phases are considered. The simulation is performed with the help of the NANOKIN code. It includes a full treatment of speciation processes in the aqueous solution, a rate equation for the dissolution of olivine, and a full account of nucleation and growth processes during the formation of secondary particles. The comparison between experimental (Lafay et al., 2014) and simulation results puts strong constraints on the simulation parameters, in particular those related to the nucleation and growth of the particles. Modeling points to an incongruent olivine dissolution and reveals a transitory precipitation of SiO2, not detected experimentally, showing that the fate of Si is more complex than a mere incorporation in lizardite. It highlights how lizardite, magnesite and SiO2 compete for the incorporation of silicon and magnesium released by the olivine dissolution.