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https://www.readbyqxmd.com/read/27897396/acid-mediated-synthesis-of-ordered-mesoporous-aluminosilicates-the-challenge-and-the-promise
#1
Selvam Parasuraman, Nunna Vamsi Krishna
A novel intrinsic hydrolysis method was employed, for the first-time, to synthesize well-ordered H-AlSBA-15 with trivalent aluminium exclusively in tetrahedral framework structure of SBA-15. Unlike other methods, which involve incorporation of aluminum ions in, both, framework (Brønsted) and non-framework (Lewis) sites of the silicate matrix, the intrinsic hydroly-sis method isomorphously substitutes aluminium ions in the tetrahedral network even at high aluminium content. This unique approach relies mainly on hydrolysis rates of inorganic (silicon and aluminium) precursors used for the preparation in such a way that the condensation occurs simultaneously so as to overcome the usually encountered difficulties in stabilizing aluminium ions in the silicate matrix...
November 29, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27886316/the-mechanism-of-large-second-harmonic-generation-enhancement-activated-by-zn-2-substitution
#2
Miriding Mutailipu, Zhi Li, Min Zhang, Dianwei Hou, Zhihua Yang, Bingbing Zhang, Hongping Wu, Shilie Pan
Substitution is an effective method to create new nonlinear optical (NLO) materials with an enhanced second harmonic generation (SHG) response. However, the large SHG enhancement caused by the substitution of Mg(2+) for Zn(2+) in an isostructural system is rare and has not been investigated yet. Here we elucidate the contribution of Zn(2+) with d(10) electronic configuration to the SHG response based on two isostructural silicates Sr2MSi2O7 (M = Zn and Mg). The powder SHG measurements show that the SHG response of Sr2ZnSi2O7 is approximately 35 times that of α-SiO2 and 7 times higher than its isostructural compound Sr2MgSi2O7...
November 25, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27809347/atomic-resolution-imaging-of-beryl-an-investigation-of-the-nano-channel-occupation
#3
V Arivazhagan, F D Schmitz, P E Vullum, A T J VAN Helvoort, B Holst
Beryl in different varieties (emerald, aquamarine, heliodor etc.) displays a wide range of colours that have fascinated humans throughout history. Beryl is a hexagonal cyclo-silicate (ring-silicate) with channels going through the crystal along the c-axis. The channels are about 0.5 nm in diameter and can be occupied by water and alkali ions. Pure beryl (Be3 Al2 Si6 O18 ) is colourless (variety goshenite). The characteristic colours are believed to be mainly generated through substitutions with metal atoms in the lattice...
November 3, 2016: Journal of Microscopy
https://www.readbyqxmd.com/read/27745960/lead-recovery-and-high-silica-glass-powder-synthesis-from-waste-crt-funnel-glasses-through-carbon-thermal-reduction-enhanced-glass-phase-separation-process
#4
Mingfei Xing, Zegang Fu, Yaping Wang, Jingyu Wang, Zhiyuan Zhang
In this study, a novel process for the removal of toxic lead from the CRT funnel glass and synchronous preparation of high silica glass powder was developed by a carbon-thermal reduction enhanced glass phase separation process. CRT funnel glass was remelted with B2O3 in reducing atmosphere. In the thermal process, a part of PbO contained in the funnel glass was reduced into metallic Pb and detached from the glass phase. The rest of PbO and other metal oxides (including Na2O, K2O, Al2O3, BaO and CaO) were mainly concentrated in the boric oxide phase...
October 6, 2016: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/27711438/preparation-and-structure-of-fe-containing-aluminosilicate-thin-films
#5
Héloïse Tissot, Linfei Li, Shamil Shaikhutdinov, Hans-Joachim Freund
In attempts to fabricate model systems of Fe-containing aluminosilicates, we studied the incorporation of iron into silicate and aluminosilicate bilayer films grown on Ru(0001). Structural characterization was performed by low energy electron diffraction, X-ray photoelectron spectroscopy, infrared reflection-absorption spectroscopy and scanning tunneling microscopy. The experimental results show that even at low concentrations Fe does not randomly substitute Si(Al) cations in the silicate framework, but segregates into a pure silicate (aluminosilicate) phase and an Fe-silicate phase which is formed by an FeO(111)-like layer underneath a silicate layer...
September 14, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27623299/radiographic-and-clinical-outcome-of-silicate-substituted-calcium-phosphate-si-cap-ceramic-bone-graft-in-spinal-fusion-procedures
#6
Marjan Alimi, Rodrigo Navarro-Ramirez, Karishma Parikh, Innocent Njoku, Christoph P Hofstetter, Apostolos J Tsiouris, Roger Härtl
STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To evaluate the radiographic and clinical outcome of silicate-substituted calcium phosphate (Si-CaP), utilized as a graft substance in spinal fusion procedures. SUMMARY OF BACKGROUND DATA: Specific properties of Si-CaP provide the graft with negative surface charge that can result in a positive effect on the osteoblast activity and neovascularization of the bone. METHODS: This study included those patients who underwent spinal fusion procedures between 2007 and 2011 in which Si-CaP was used as the only bone graft substance...
September 10, 2016: Clinical Spine Surgery
https://www.readbyqxmd.com/read/27613416/solidification-and-immobilization-of-mswi-fly-ash-through-aluminate-geopolymerization-based-on-partial-charge-model-analysis
#7
Lei Zheng, Wei Wang, Xingbao Gao
This study presents an integrated synopsis of the solidification and immobilization mechanisms of fly ash-based geopolymers. A rational analysis of the ion reactions involved in geopolymerization was conducted using the partial charge model (PCM). The following conclusions were obtained: (1) heavy metal cations cannot be immobilized as counter cations through exchange with Na(+); (2) isomorphous substitution of heavy metals in the geopolymer can be expected from the condensation reaction between the hydrolyzed heavy metal species and aluminosilicate; (3) the hydrolyzed species condensation could result in solidification and immobilization and be promoted by aluminates; and (4) a geopolymer with the highest immobilization and solidification efficiency can be obtained at an intermediate pH value...
September 6, 2016: Waste Management
https://www.readbyqxmd.com/read/27612803/effect-of-ti-4-on-in-vitro-bioactivity-and-antibacterial-activity-of-silicate-glass-ceramics
#8
Madeeha Riaz, Rehana Zia, Farhat Saleemi, Tousif Hussain, Farooq Bashir, Hafeez Ikhram
A novel glass-ceramic series in (48-x) SiO2-36 CaO-4 P2O5-12 Na2O-xTiO2 (where x=0, 3.5, 7, 10.5 and 14mol %) system was synthesized by crystallization of glass powders, obtained by melt quenching technique. The differential scanning calorimetric analysis (DSC) was used to study the non-isothermal crystallization kinetics of the as prepared glasses. The crystallization behaviour of glasses was analyzed under non-isothermal conditions, and qualitative phase analysis of glass-ceramics was made by X-ray diffraction...
December 1, 2016: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/27612739/nanostructured-silicate-substituted-calcium-phosphate-nanosicaps-nanoparticles-efficient-calcium-phosphate-based-non-viral-gene-delivery-systems
#9
Sudhanshu Shekhar, Abhijit Roy, Daeho Hong, Prashant N Kumta
Nanostructured ceramic particles, particularly, nanoparticles of calcium phosphate (CaP) remain an attractive option among the various types of non-viral gene delivery vectors studied because of their safety, biocompatibility, biodegradability, and ease of handling as well as their adsorptive capacity for DNA. We have accordingly developed an enhanced version of nanostructured calcium phosphates (NanoCaPs), by substituting known amounts of silicate for phosphate in the hydroxyapatite (HA) lattice (NanoSiCaPs)...
December 1, 2016: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/27537252/hard-magnetism-in-structurally-engineered-silica-nanocomposite
#10
Hyon-Min Song, Jeffrey I Zink
Creation of structural complexity by simple experimental control will be an attractive approach for the preparation of nanomaterials, as a classical bottom-up method is supplemented by a more efficient and more direct artificial engineering method. In this study, structural manipulation of MCM-41 type mesoporous silica is investigated by generating and imbedding hard magnetic CoFe2O4 nanoparticles into mesoporous silica. Depending on the heating rate and target temperature, mesoporous silica undergoes a transformation in shape to form hollow silica, framed silica with interior voids, or melted silica with intact mesostructures...
September 21, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27528855/comparison-of-two-synthetic-bone-graft-products-in-a-rabbit-posterolateral-fusion-model
#11
Douglas Fredericks, Emily B Petersen, Nicole Watson, Nicole Grosland, Katherine Gibson-Corley, Joseph Smucker
BACKGROUND: The drawbacks of iliac crest autograft as graft material for spine fusion are well reported. Despite continued modifications to improve bone healing capacity, the efficacy of synthetic graft materials as stand-alone replacements remains uncertain. The rabbit posterolateral fusion model is an established environment for testing of fusion concepts. It offers the opportunity to obtain radiographic, biomechanical and histological data on novel fusion materials. The objective of this study was to compare the spine fusion capability of two synthetic bone graft products in an established rabbit posterolateral spine fusion (PLF) model: Signafuse® Bioactive Bone Graft Putty and Actifuse® ABX...
2016: Iowa Orthopaedic Journal
https://www.readbyqxmd.com/read/27466864/stem-cells-in-spine-surgery
#12
Kenneth K Hansraj
INTRODUCTION: Spine surgeons are embracing advanced biologic technologies in an attempt to help millions of people achieve a better outcome in spine surgery. These new technologies may be complicated to understand, partly because the contribution of different types of cells has not been definitively identified. This paper describes the characteristics of the stem cells used in spine surgery, including their actions and possible complications. The description necessitates an overview of all studies to date on the use of stem cells in spine surgery, as well as other cells used in cellular therapy...
July 29, 2016: Surgical Technology International
https://www.readbyqxmd.com/read/27428393/to-the-editor
#13
Bradley K Weiner, Paige E Vargo
No abstract text is available yet for this article.
September 1, 2016: Spine
https://www.readbyqxmd.com/read/27359353/to-the-editor
#14
Kern Singh, Sreeharsha V Nandyala, Alejandro Marquez-Lara, Steven J Fineberg, Miguel Pelton
No abstract text is available yet for this article.
September 1, 2016: Spine
https://www.readbyqxmd.com/read/27254281/acid-resistant-calcium-silicate-based-composite-implants-with-high-strength-as-load-bearing-bone-graft-substitutes-and-fracture-fixation-devices
#15
Chung-Kai Wei, Shinn-Jyh Ding
To achieve the excellent mechanical properties of biodegradable materials used for cortical bone graft substitutes and fracture fixation devices remains a challenge. To this end, the biomimetic calcium silicate/gelatin/chitosan oligosaccharide composite implants were developed, with an aim of achieving high strength, controlled degradation, and superior osteogenic activity. The work focused on the effect of gelatin on mechanical properties of the composites under four different kinds of mechanical stresses including compression, tensile, bending, and impact...
September 2016: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/27216747/luminescence-enhancement-of-sr1-x-mx-2-sio4-eu-2-phosphors-with-m-ca-2-zn-2-partial-substitution-for-white-light-emitting-diodes
#16
Yulong Wang, Wentao Zhang, Yang Gao, Jianping Long, Junfeng Li
Eu(2) (+) -doped Sr2 SiO4 phosphor with Ca(2) (+) /Zn(2) (+) substitution, (Sr1-x Mx )2 SiO4 :Eu(2) (+) (M = Ca, Zn), was prepared using a high-temperature solid-state reaction method. The structure and luminescence properties of Ca(2) (+) /Zn(2) (+) partially substituted Sr2 SiO4 :Eu(2) (+) phosphors were investigated in detail. With Ca(2) (+) or Zn(2) (+) added to the silicate host, the crystal phase could be transformed between the α-form and the β-form of the Sr2 SiO4 structure. Under UV excitation at 367 nm, all samples exhibit a broad band emission from 420 to 680 nm due to the 4f(6) 5d(1)  → 4f(7) transition of Eu(2) (+) ions...
May 24, 2016: Luminescence: the Journal of Biological and Chemical Luminescence
https://www.readbyqxmd.com/read/27146211/a-tightly-regulated-expression-system-for-e-coli-using-supersaturated-silicic-acid
#17
Yasuhiro Fujino, Ryo Tanoue, Takushi Yokoyama, Katsumi Doi
OBJECTIVE: To develop a new expression system regulated by a ferric uptake regulator in which silicic acid is used as an inducer. RESULTS: Fur box (binding site for Fur) was substituted for the lac operator to regulate the expression of GFP with the lac promoter. Since the addition of supersaturated silicic acid invokes iron deficiency, supersaturated silicic acids were used as an inducer. GFP expression was dependent on silica concentration, and the expression level without silica was negligible...
August 2016: Biotechnology Letters
https://www.readbyqxmd.com/read/27124890/in-vitro-and-in-vivo-evaluation-of-silicate-coated-polyetheretherketone-fabricated-by-electron-beam-evaporation
#18
Jin Wen, Tao Lu, Xiao Wang, Lianyi Xu, Qianju Wu, Hongya Pan, Donghui Wang, Xuanyong Liu, Xinquan Jiang
Intrinsic bioinertness severely hampers the application of polyetheretherketone (PEEK), although in the field of dentistry it is considered to be an ideal titanium substitute implanting material. In this study, a bioactive silicate coating was successfully introduced onto PEEK surface by using electron beam evaporation (EBE) technology to improve its bioactivity and osseointegration of PEEK. Through controlling the duration of EBE, the incorporated amounts of silicon (Si) could be exquisitely adjusted to obtain proper biofunctionality, as assessed by cell adhesion, proliferation, osteogenic gene expression, and protein detection...
June 1, 2016: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/27062972/new-family-of-materials-with-negative-coefficients-of-thermal-expansion-the-effect-of-mgo-coo-mno-nio-or-cuo-on-the-phase-stability-and-thermal-expansion-of-solid-solution-phases-derived-from-bazn2si2o7
#19
Christian Thieme, Tina Waurischk, Stephan Heitmann, Christian Rüssel
Recently, a silicate with the composition SrxBa1-xZn2Si2O7 was reported, which exhibits a negative coefficient of thermal expansion. The compound BaZn2Si2O7 shows a highly positive coefficient of thermal expansion up to a temperature of 280 °C and then transfers to a high temperature phase, which exhibits a coefficient of thermal expansion near zero or negative over a limited temperature range up to around 500 °C. This high temperature modification can be stabilized to room temperature if Ba(2+) is replaced by Sr(2+)...
May 2, 2016: Inorganic Chemistry
https://www.readbyqxmd.com/read/27023623/glass-polyalkenoate-cements-designed-for-cranioplasty-applications-an-evaluation-of-their-physical-and-mechanical-properties
#20
Basel A Khader, Declan J Curran, Sean Peel, Mark R Towler
Glass polyalkenoate cements (GPCs) have potential for skeletal cementation. Unfortunately, commercial GPCs all contain, and subsequently release, aluminum ions, which have been implicated in degenerative brain disease. The purpose of this research was to create a series of aluminum-free GPCs constructed from silicate (SiO₂), calcium (CaO), zinc (ZnO) and sodium (Na₂O)-containing glasses mixed with poly-acrylic acid (PAA) and to evaluate the potential of these cements for cranioplasty applications. Three glasses were formulated based on the SiO₂-CaO-ZnO-Na₂O parent glass (KBT01) with 0...
2016: Journal of Functional Biomaterials
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