167,481 research outputs found
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
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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
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
Kapsa (Rigida) Cao & Zhang
No full textKey to males of Kapsa (Rigida) Cao & Zhang sgen. n. 1. Anal tube appendage rudimentary, small, not hooked at apex...................... K. apicispina Yang & Zhang sp. nov. - Anal tube appendage well developed, hooked apically (Figs 5 b, 6 b, 8 b, 9 b, 10 e, 11 c, 12 c, 13 c)........................ 2 2. Anal tube appendage curved cephalad in larteral view................................ K. maculata Sohi & Mann, 1992 - Anal tube appendage curved caudad in lateral view (Figs 5 b, 6 b, 8 b, 9 b, 10 e, 11 c, 12 c, 13 c)........................... 3 3. Aedeagus without ventral process near base of shaft (Figs 5 h, 6g, 11 i, 13g)........................................ 4 - Aedeagus with unpaired ventral process near base of shaft (Figs 8 h, 9g, 10 j, 12 i)................................... 7 4. Aedeagal shaft with ventral process near apex (Figs 6 g, 13g)................................................... 5 - Aedeagal shaft without process (Figs 5 h, 11 i)............................................................... 6 5. Paramere forked apically, with apical and basal branch, aedeagal shaft with small thornlike process ventro-apically (Fig. 6 e, g)...................................................................... K. aculeiformis Cao & Zhang sp. nov. - Paramere bifurcated apically, with dorsal and ventral branch, aedeagal shaft with large serrated protrusion ventro-medially (Fig. 13 e, g)................................................................ K. serrata Cao & Zhang sp. nov. 6. Apex of paramere straight, aedeagal shaft expanded in lateral view (Fig. 11 f, i)......... K. imminuta Yang & Zhang sp. nov. - Apex of paramere sinuate, aedeagal shaft not expanded in lateral view (Figs 5 e, f, h).......... K. alba Dworakowska, 1981 7. Ventral process not extended to midlength of aedeagal shaft (Figs 8 h, 9g)......................................... 8 - Ventral process surpassing midlength of aedeagal shaft (Figs 10 j, 12 i)........................................... 10 8. Paramere footlike apically, heel expanded, ventral processes of aedeagus rounded in lateral view (Fig. 9 e, g)...................................................................................... K. explanata Cao & Zhang sp. nov. - Paramere with second extension apically, ventral processes of aedeagus pointed in lateral view (Fig. 8 h, i)............... 9 9. Aedeagal shaft expanded in lateral view, almost straight............................... K. minuta Dworakowska, 1994 - Aedeagal shaft not expanded in lateral view, obviously curved ventrad (Fig. 8 h)........... K. brevis Cao & Zhang sp. nov. 10. Ventral process of aedeagus with broadened and concave apex in caudal view....... K. borealis Dworakowska & Sohi, 1978 - Ventral process of aedeagus pointed apically in caudal view (Figs 10 k, 12 j)....................................... 11 11. Paramere forked apically (Fig. 10 h).............................................. K. furcata Cao & Zhang sp. nov. - Paramere not forked apically (Fig. 12 g)................................................................... 12 12. Aedeagus with base of ventral process broader than that of shaft in lateral view (Fig. 12 i).................................................................................................. K. megaprocessa Cao & Zhang sp. nov. - Aedeagus with base of ventral process slightly narrower than that of shaft in lateral view......................................................................................... K. simlensis Dworakowska, Nagaich & Singh, 1978Published as part of Yang, Meixia, Cao, Yanghui & Zhang, Yalin, 2013, Taxonomic study of the genus Kapsa Dworakowska with a new subgenus, and new combinations and records for Tautoneura Anufriev (Hemiptera: Cicadellidae: Typhlocybinae: Erythroneurini), pp. 117-142 in Zootaxa 3630 (1) on page 128, DOI: 10.11646/zootaxa.3630.1.4, http://zenodo.org/record/22287
Structure and viscosity of CaO–Al₂O₃–B₂O₃ based mould fluxes with varying CaO–Al₂O₃ mass ratios
No full textAbstract
The effect of CaO/Al₂O₃ ratio on the structure of CaO–Al₂O₃–B₂O₃ based glassy mould fluxes was investigated by employing ²⁷Al and ¹¹B Triple Quantum Magic-angle spinning nuclear magnetic resonance (3QMAS-NMR) and Raman spectroscopy. ²⁷Al and ¹¹B 3QMAS-NMR spectrums showed that Al3+ mainly forms [AlO₄] as a network former and B3+ mainly forms [BO₃] groups in CaO–Al₂O₃–B₂O₃ based glasses. Raman spectrum showed existences of different [AlO₄] structure units and BO₃ pyro-borate units. In addition, deconvolution results on Raman spectrums indicate that the degree of polymerization of aluminate network in CaO–Al₂O₃–B₂O₃ based glasses decreases with the increase of CaO–Al₂O₃–B₂O₃ ratio. The effect of CaO–Al₂O₃–B₂O₃ ratio on viscosity of CaO–Al₂O₃–B₂O₃ based glassy mould fluxes was investigated by employing the rotating-cylinder method. The viscosity decreases with increasing CaO–Al₂O₃–B₂O₃ ratio in CaO–Al₂O₃–B₂O₃ based mould flux. Correlation between viscosity and structural information of investigated mould fluxes was explored
PENGHILANGAN ZAT WARNA RHODAMIN B MENGGUNAKAN FOTOKATALIS KOMPOSIT CAO/TIO2 MENGGUNAKAN CANGKANG KERANG DARAH (ANADARA GRANOSA) SEBAGAI SUMBER CAO
No full textSintesis fotokatalis komposit CaO/TiO2 menggunakan metode impregnasi basah danuji aktivitas fotokatalitiknya pada degradasi zat warna rhodamin B telah dilakukan.Kalsium oksida dipreparasi dari cangkang kerang darah melalui metode dekomposisitermal. Titanium dioksida disintesis menggunakan (Ti[OCH(CH3)2]4) sebagaiprekursor dengan metode sol-gel. Karakterisasi material yang dihasilkan dilakukanmenggunakan instrumen X-Ray Diffraction (XRD), Scanning Electron MicroscopyEnergy-Dispersive X-Ray Spectroscopy (SEM-EDS), Brunaeur Emmet Teller (BET)dan Diffuse Reflectance Spectroscopy UV-Vis (DRS UV-Vis). TiO2 yang diperolehmemiliki fasa anatase dan CaO memiliki fasa portlandit. Komposit 15%-CaO/TiO2memiliki luas permukaan yang lebih rendah dari TiO2, energi celah pita sedikit lebihbesar dari TiO2 dan ukuran rata-rata pori lebih besar dari TiO2. Hasil uji aktivitasfotokatalitik pada penghilangan zat warna rhodamin B (RhB) menunjukkan komposit15%-CaO/TiO2 memiliki aktivitas yang paling tinggi dibandingkan denganpenambahan CaO 5% b/b, 25%b/b dan 35% b/b. Komposit 15%-CaO/TiO2 dapatmendegradasi zat warna rhodamin B hingga 97,77% dibawah irradiasi sinar UV padakondisi optimum pH larutan rhodamin B 5, massa fotokatalis 250 mg, konsentrasi zatwarna rhodamin B 5 ppm dan waktu irradiasi selama 120 menit. Komposit 15%-CaO/TiO2 memiliki aktivitas lebih tinggi dibawah irradiasi sinar mataharidibandingkan dengan sinar UV. Penambahan CaO terbukti dapat meningkatkanaktivitas fotokatalitik TiO2
Process Optimization for Ethyl Ester Production in Fixed Bed Reactor Using Calcium Oxide Impregnated Palm Shell Activated Carbon (CaO/PSAC)
No full textThe continuous production of ethyl ester was studied by using a steady-state fixed bed reactor (FBR). Transesterification of palm stearin (PS) and waste cooking palm oil (WCPO) with ethanol in the presence of calcium oxide impregnated palm shell activated carbon (CaO/PSAC) solid catalyst was investigated. This work was determined the optimum conditions for the production of ethyl ester from PS and WCPO in order to obtain fatty acid ethyl ester (FAEE) with the highest yield. The effects of reaction variables such as residence time, ethanol/oil molar ratio, reaction temperature, catalyst bed height and reusability of catalyst in a reactor system on the yield of biodiesel were considered. The optimum conditions were the residence time 2-3 h, ethanol/oil molar ratio 16-20, reaction temperature at 800C, and catalyst bed height 300 mm which yielded 89.46% and 83.32% of the PS and WCPO conversion, respectively. CaO/PSAC could be used repeatedly for 4 times without any activation treatment and no obvious activity loss was observed. It has potential for industrial application in the transesterification of triglyceride (TG). The fuel properties of biodiesel were determine
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