93,084 research outputs found
Novel sol–gel preparation of (PO)–(CaO)–(NaO)–(TiO) bioresorbable glasses (X = 0.05, 0.1, and 0.15)
No full textQuaternary phosphate-based glasses in the PO–CaO–NaO–TiO system with a fixed PO and CaO content of 40 and 25 mol% respectively have been successfully synthesised via sol–gel method and bulk, transparent samples were obtained. The structure, elemental proportion, and thermal properties of stabilised sol–gel glasses have been characterised using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), P nuclear magnetic resonance (P NMR), titanium K-edge X-ray absorption near-edge structure (XANES), fourier transform infrared (FTIR) spectroscopy, and differential thermal analysis (DTA). The XRD results confirmed the amorphous nature for all stabilized sol–gel derived glasses. The EDX result shows the relatively low loss of phosphorus during the sol–gel process and Ti K-edge XANES confirmed titanium in the glass structure is in mainly six-fold coordination environment. The P NMR and FTIR results revealed that the glass structure consist of mainly Q and Q phosphate units and the Ti cation was acting as a cross-linking between phosphate units. In addition DTA results confirmed a decrease in the glass transition and crystallisation temperature with increasing NaO content. Ion release studies also demonstrated a decrease in degradation rates with increasing TiO content therefore supporting the use of these glasses for biomedical applications that require a degree of control over glass degradation. These sol–gel glasses also offer the potential to incorporate proactive molecules for drug delivery application due to the low synthesis temperature employed
Effect of CaO content in raw material on the mineral composition of ferric-rich sulfoaluminate clinker
No full textFerric-rich calcium sulfoaluminate (FR-CSA) cement is an eco-friendly cement. Fe2O3 exists in different minerals of FR-CSA clinker, e.g., Ca4Al2Fe2O10 (C4AF), Ca2Fe2O5 (C2F), and Ca4Al6-2xFe2xSO16 (C4A3-xFxS-). The mineral composition depends on the chemical composition of the raw materials and significantly determines the reactivity of FR-CSA cement. To optimize the phase composition of the FR-CSA clinker, chemical reagent raw mixtures with different amounts of CaO were used to prepare the FR-CSA clinker. X-ray diffraction (XRD) analysis, Rietveld quantitative phase analysis (RQPA), Fourier Transform Infrared spectroscopy (FT-IR), and scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS) were used to identify the mineralogical conditions of the FR-CSA clinker. The results indicated that the amounts of CaO in raw materials greatly affected the iron-bearing phase formation in the FR-CSA clinker. With decreasing CaO content involved in calcination reaction, the amounts of Fe2O3 incorporated in C4A3-xFxS- increased up to 17.72 wt% (where x = 0.36). The findings make it possible to optimize the mineral composition of the FR-CSA clinker by changing the CaO content in raw materials. Furthermore, low CaO content in the raw material is beneficial to the formation of C4A3-xFxS-, which enables the use of solid wastes containing low calcium for producing FR-CSA cement.Accepted author manuscriptMaterials and Environmen
Melt densities in the CaO-FeO-Fe2O3-SiO2 system and the compositional dependence of the partial molar volume of ferric iron in silicate melts
No full textThe densities of 10 melts in the CaO-FeO-Fe2O3-SiO2 system were determined in equilibrium with air, in the temperature range of 1200 to 1550°C, using the double-bob Archimedean technique. Melt compositions range from 6 to 58 wt% SiO2, 14 to 76 wt% Fe2O3 and 10 to 46 wt% CaO. The ferric-ferrous ratios of glasses drop-quenched from loop fusion equilibration experiments were determined by 57Fe Mössbauer spectroscopy.
Melt densities range from 2.689 to 3.618 gm/cm3 with a mean standard deviation from replicate experiments of 0.15%. Least-squares regressions of molar volume versus molar composition have been performed and the root mean squared deviation shows that a linear combination of partial molar volumes for the oxide components (CaO, FeO, Fe2O3 and SiO2) cannot describe the data set within experimental error. Instead, the inclusion of excess terms in CaFe3+ and CaSi (product terms using the oxides) is required to yield a fit that describes the experimental data within error. The nonlinear compositional-dependence of the molar volumes of melts in this system can be explained by structural considerations of the roles of Ca and Fe3+.
The volume behavior of melts in this system is significantly different from that in the Na2O-FeO-Fe2O3-SiO2 system, consistent with the proposal that a proportion of Fe3+ in melts in the CaO-FeO-Fe2O3-SiO2 system is not tetrahedrally-coordinated by oxygen, which is supported by differences in 57Fe Mössbauer spectra of glasses. Specifically, this study confirms that the 57Fe Mössbauer spectra exhibit an area asymmetry and higher values of isomer shift of the ferric doublet that vary systematically with composition and temperature (this study; Dingwell and Virgo, 1987, 1988). These observations are consistent with a number of other lines of evidence (e.g., homogeneous redox equilibria, Dickenson and Hess, 1986; viscosity, Dingwell and Virgo, 1987,1988). Two species of ferric iron, varying in proportions with temperature, composition and redox state, are sufficient to describe the above observations.
The presence of more than one coordination geometry for Fe3+ in low pressure silicate melts has several implications for igneous petrogenesis. The possible effects on compressibility, the pressure dependence of the redox ratio, and redox enthalpy are briefly noted
Phase Diagram Study for the PbO-ZnO-CaO-SiO2-"Fe2O3" System in Air with CaO/SiO2 in 1.1 and PbO/(CaO+SiO2) in 2.4 Weight Ratios
No full textAn experimental study on the phase equilibrium and the liquidus isotherms for the PbO-ZnO-CaO-SiO2-"Fe2O3" system with CaO/SiO2 in 1.1 and PbO/(CaO+SiO2) in 2.4 weight ratios, respectively, was carried out in the temperature range 1100-1300ºC (1373-1573 K). High temperature phases were determined by the equilibrium-quenching method. Results are presented in the form of pseudo-ternary sections "Fe2O3"-ZnO-(PbO+CaO+SiO2). X-Ray diffraction (XRD) and SEM-EDS results showed that the phase equilibria in this system are dominated by the high melting temperature spinel and zincite phases. It was observed that if the system is at a temperature below 1300ºC and the total (Fe2O3 + ZnO) is greater than 20 wt%, spinel and/or zincite will be present in the slag system. As an application of the phase diagram, the liquid phase compositions below the liquidus surface were estimated, then their viscosities were calculated using FACTSage software.</div
Traces and shards of self-injury: Strange accounting with “Author X”
No full textIn this strange account autoethnography, three or four authors explore their lived experiences with self-injury. Strange accounting is both a post-modern style of text, and a method for keeping identities concealed when risks and secrets are in play. Author X, a post-modern place-keeper for an anonymous author who may or may not have contributed to this manuscript, introduces a new dimension and layer of concealment. With Author X in-play and under erasure, the reader will never be sure if there were three or four authors on this manuscript. Through strange accounting, a post-structuralist/postmodernist frame will be applied to understanding the self-injury experience. We frame self-injury as a social practice and, for some, an everyday norm, while remaining acutely aware of the stigma surrounding the topic of self-injury. Each of us, coupled with Author X, provide the others cover to trace stories of self-injury through the literature, our flesh, and our lives
Process engineering and development of post-combustion CO2 separation from fuels using limestone in CaO-looping cycle
No full textGlobal CO2 emissions produced by energy-related processes, mainly power plants, have increased rapidly in recent decades; and are widely accepted as the dominant contributor to the greenhouse gas (GHG) effect and consequent climate changes. Among countermeasures against the emissions, CO2 capture and storage (CCS) is receiving much attention. Capture of CO2 is the core step of CCS as it contributes around 75% of the overall cost, and may increase the production costs of electricity by over 50%. The reduction in capture costs is one of the most challenging issues in application of CCS to the energy industry. Using limestone in CaO-looping cycles is a promising capture technology to provide a cost-effective separation process to remove CO2 content from power plants operations. Limestone has the advantage of being relatively abundant and cheap, and that has already been widely used as a sorbent for sulphur capture. However, this technology suffers from a critical challenge caused by the decay in the sorbent capture capacity during cyclic carbonation/calcination, which results in the need for more sorbent make-up; hence a reduction in cost efficiency of the technology. The performance of sorbent influenced by several operating and reaction conditions. Therefore, much research involves investigation of influencing factors and different methods to reduce the sorbent deactivation. Cont/d
Ben cao wan fang zhen xian
No full textV.1. 本草綱目藥品總目 : 卷五至五十二 / 蔡烈先輯 -- 瀕湖脉學 -- 奇經八脈攷 / 李時珍撰輯 -- 脉訣攷證 -- v.1-2. 本草綱目圖 : [三卷] -- v.3-10. 本草綱目 : 五十二卷 / 李時珍編輯 -- v.11-12. 本草綱目拾遺 : 十卷 / 趙學敏輯 -- v.12. 本草萬方鍼綫 : 八卷 / 蔡烈先輯.V.1. Ben cao gang mu yao pin zong mu : juan wu zhi wu shi er / Cai Liexian ji -- Bin hu mai xue -- Qi jing ba mai kao / Li Shizhen zhuan ji -- Mai jue kao zheng -- v.1-2. Ben cao gang mu tu : [san juan] -- v.3-10. Ben cao gang mu : wu shi er juan / Li Shizhen bian ji -- v.11-12. Ben cao gang mu shi yi : shi juan / Zhao Xuemin ji -- v.12. Ben cao wan fang zhen xian : ba juan / Cai Liexian ji.李時珍編輯 ; 吳毓昌較訂.綫裝.框13.3x9公分, 12行, 每行字數不等. 白口, 四周雙邊, 單黑魚尾. 版心上鐫題名, 中鐫卷次, 小題, 下鐫葉次.內封背頁牌記鐫"光緖戊子[1888]秋鴻寳齋石印"《中國中醫古籍總目》02511著錄.鈐"莊兆祥印"朱, 白文各一方.Xian zhuang.Kuang 13.3 x 9 gong fen, 12 hang, mei hang zi shu bu deng. Bai kou, si zhou shuang bian, dan hei yu wei. Ban xin shang juan ti ming, zhong juan juan ci, xiao ti, xia juan ye ci.Nei feng bei ye pai ji juan "Guangxu wu zi [1888] qiu Hong bao zhai shi yin"Detailed notes in vernacular field only.Li Shizhen bian ji ; Wu Yuchang jiao ding.Qian "Zhuang Zhaoxiang yin" zhu, bai wen ge yi fang
Electronic and photocatalytic properties of transition metal decorated molybdenum disulfide
No full textAbstractThis thesis is dedicated to realizations and physical understanding of electronic and photocatalytic properties after decorating transition metals to the semiconducting molybdenum disulfide. Synthesized via facile wet chemical methods, the MoS₂-Au, MoS₂-Au-Ni and MoS₂-Ag-Ni composites were formed as binary or ternary compounds. The Au nanoparticles are stably joined to the MoS₂ matrix without deteriorating layered structures of the host. After introducing the Au nanoglue as a common buffer, a metallic contact is reached between Ni and MoS₂, and attributed to new electron migration channel via MoS₂ edge contact. Adapting the Ag as the buffer element can attach the Ni to the basal plane of the MoS₂ beside edge contact. The Ni-Ag-MoS₂ composite effectively splits water under visible light irradiation and produce hydrogen. The excellent photocatalytic activity is attributed to effective charge migration through dangling bonds at the MoS2-Ag-Ni alloy interface and the activation of MoS₂ basal planes.Original papersOriginal papers are not included in the electronic version of the dissertation.Cao, W., Pankratov, V., Huttula, M., Shi, X., Saukko, S., Huang, Z., & Zhang, M. (2015). Gold nanoparticles on MoS₂ layered crystal flakes. Materials Chemistry and Physics, 158, 89–95. https://doi.org/10.1016/j.matchemphys.2015.03.041Shi, X., Posysaev, S., Huttula, M., Pankratov, V., Hoszowska, J., Dousse, J.-C., … Cao, W. (2018). Metallic Contact between MoS₂ and Ni via Au Nanoglue. Small, 14(22), 1704526. https://doi.org/10.1002/smll.201704526Self-archived versionShi, X., Huttula, M., Pankratov, V., Hoszowska, J., Dousse, J.-C., Zeeshan, F., … Cao, W. (2018). Quantification of bonded Ni atoms for Ni-MoS₂ metallic contact through X-ray photoemission electron microscopy. Microscopy and Microanalysis, 24(S2), 458−459. https://doi.org/10.1017/S1431927618014526Self-archived versionX. Shi, M. Zhang, W. Cao, X. Wang, M. Huttula. (2018). Efficient photocatalytic hydrogen evolution via activated multilayer MoS₂. Manuscript in preparation.Shi, X., Huang, Z., Huttula, M., Li, T., Li, S., Wang, X., … Cao, W. (2018). Introducing Magnetism into 2D Nonmagnetic Inorganic Layered Crystals: A Brief Review from First-Principles Aspects. Crystals, 8(1), 24. https://doi.org/10.3390/cryst8010024Self-archived versionOsajulkaisutOsajulkaisut eivät sisälly väitöskirjan elektroniseen versioon.Cao, W., Pankratov, V., Huttula, M., Shi, X., Saukko, S., Huang, Z., & Zhang, M. (2015). Gold nanoparticles on MoS₂ layered crystal flakes. Materials Chemistry and Physics, 158, 89–95. https://doi.org/10.1016/j.matchemphys.2015.03.041Shi, X., Posysaev, S., Huttula, M., Pankratov, V., Hoszowska, J., Dousse, J.-C., … Cao, W. (2018). Metallic Contact between MoS₂ and Ni via Au Nanoglue. Small, 14(22), 1704526. https://doi.org/10.1002/smll.201704526Rinnakkaistallennettu versioShi, X., Huttula, M., Pankratov, V., Hoszowska, J., Dousse, J.-C., Zeeshan, F., … Cao, W. (2018). Quantification of bonded Ni atoms for Ni-MoS₂ metallic contact through X-ray photoemission electron microscopy. Microscopy and Microanalysis, 24(S2), 458−459. https://doi.org/10.1017/S1431927618014526Rinnakkaistallennettu versioX. Shi, M. Zhang, W. Cao, X. Wang, M. Huttula. (2018). Efficient photocatalytic hydrogen evolution via activated multilayer MoS₂. Manuscript in preparation.Shi, X., Huang, Z., Huttula, M., Li, T., Li, S., Wang, X., … Cao, W. (2018). Introducing Magnetism into 2D Nonmagnetic Inorganic Layered Crystals: A Brief Review from First-Principles Aspects. Crystals, 8(1), 24. https://doi.org/10.3390/cryst8010024Rinnakkaistallennettu versioAcademic Dissertation to be presented with the assent of the Faculty of Science, University of Oulu for public discussion in the Auditorium Saalastinsali, on September 12th, 2018, at 12 o’clock noon.Abstract
This thesis is dedicated to realizations and physical understanding of electronic and photocatalytic properties after decorating transition metals to the semiconducting molybdenum disulfide. Synthesized via facile wet chemical methods, the MoS₂-Au, MoS₂-Au-Ni and MoS₂-Ag-Ni composites were formed as binary or ternary compounds. The Au nanoparticles are stably joined to the MoS₂ matrix without deteriorating layered structures of the host. After introducing the Au nanoglue as a common buffer, a metallic contact is reached between Ni and MoS₂, and attributed to new electron migration channel via MoS₂ edge contact. Adapting the Ag as the buffer element can attach the Ni to the basal plane of the MoS₂ beside edge contact. The Ni-Ag-MoS₂ composite effectively splits water under visible light irradiation and produce hydrogen. The excellent photocatalytic activity is attributed to effective charge migration through dangling bonds at the MoS2-Ag-Ni alloy interface and the activation of MoS₂ basal planes
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
- …
