New Method for Estimation of the Magnesium Fraction in Magnesian Calcite

2004 ◽  
Vol 443-444 ◽  
pp. 55-58 ◽  
Author(s):  
B. Gržeta ◽  
D. Medaković ◽  
S. Popović
Keyword(s):  
Intensity Ratio ◽  
Sea Urchins ◽  
New Method ◽  
Xrd Pattern ◽  
Sterechinus Neumayeri ◽  
Xrd Study ◽  
Profile Fitting ◽  
Magnesian Calcite

A new method for estimation of the magnesium fraction in magnesian calcite is described. It involves measuring the XRD pattern of magnesian calcite in a narrow 20 range and individual profile fitting of diffraction lines 113 and 202. The intensity ratio I113/I202 is linearly correlated with the Mg fraction. The method resulted from an XRD study of adult sea urchins Sterechinus neumayeri.

Preliminary Study on the Electrolysis of Titanium Oxysalt

2013 ◽  
Vol 734-737 ◽  
pp. 2430-2433 ◽  
Author(s):  
Kun Zhao ◽  
Yao Wu Wang ◽  
Shao Hu Tao ◽  
Nai Xiang Feng
Keyword(s):  
Titanium Alloys ◽  
Aluminium Alloy ◽  
New Method ◽  
Constant Current ◽  
Xrd Pattern ◽  
Preliminary Study ◽  
Titanium Aluminium

A new method for producing titanium and titanium alloys was studied at this paper. The experiment results indicate that Na2TiO3 could be synthesizing by heating at 450°C using NaOH and TiO2 powders.Metallic titanium was observed in XRD pattern of the electrolytes after experiment by means of constant-current electrolytic Na2TiO3 in a CaCl2-CaF2 melt at 850°C.Thendepending on the electrolytical residua,titanium aluminium alloy could be obtained by calcining with Al powders.

scholarly journals Detecting Variable Resistance by Fluorescence Intensity Ratio Technology

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2400 ◽  
Author(s):  
Wanjun Sheng ◽  
Xiangfu Wang ◽  
Yong Tao ◽  
Xiaohong Yan
Keyword(s):  
Fluorescence Intensity ◽  
Intensity Ratio ◽  
Negative Temperature ◽  
Relative Sensitivity ◽  
New Method ◽  
Fluorescence Intensity Ratio ◽  
Time Intervals ◽  
Variable Resistance ◽  
Reduced Graphene ◽  
Short Time

We report a new method for detecting variable resistance during short time intervals by using an optical method. A novel variable-resistance sensor composed of up-conversion nanoparticles (NaYF4:Yb3+,Er3+) and reduced graphene oxide (RGO) is designed based on characteristics of a negative temperature coefficient (NTC) resistive element. The fluorescence intensity ratio (FIR) technology based on green and red emissions is used to detect variable resistance. Combining the Boltzmann distributing law with Steinhart–Hart equation, the FIR and relative sensitivity SR as a function of resistance can be defined. The maximum value of SR is 1.039 × 10−3/Ω. This work reports a new method for measuring variable resistance based on the experimental data from fluorescence spectrum.

A new method for Rietveld clay analysis. Part I. Use of a universal measured standard profile for Rietveld quantification of montmorillonites

1994 ◽  
Vol 9 (2) ◽  
pp. 119-123 ◽  
Author(s):  
J. C. Taylor ◽  
C. E. Matulis
Keyword(s):  
Quantitative Analysis ◽  
Chemical Treatment ◽  
Rietveld Analysis ◽  
Preferred Orientation ◽  
New Method ◽  
Orientation Parameter ◽  
Xrd Pattern ◽  
Full Profile ◽  
Analysis System ◽  
Standard Profile

A new method for the quantification of montmorillonite by full-profile Rietveld analysis of the XRD profile is presented. A measured standard XRD pattern of Algerian bentonite was used to construct a universally applicable montmorillonite (hkl) file for use with a P.C. based Rietveld XRD quantitative analysis system, SIROQUANT. “Universal” means that the standard file can be used for montmorillonites from other localities. The validity of the montmorillonite standard profile was tested with weighed mixtures of quartz and different standard montmorillonites. The results show the montmorillonite observed (hkl) file is generally applicable (i.e., universal), and can be used to quantify montmorillonite in any mineral without modification or chemical treatment of the sample. Two halfwidth functions were used for the montmorillonite, corresponding to the sharp (hk0) and broad (hkl) classes of reflections. A March preferred orientation parameter for montmorillonite was also refined.

Multireflection RIR and intensity normalizations for quantitative analyses: Applications to feldspars and zeolites

1995 ◽  
Vol 10 (1) ◽  
pp. 47-55 ◽  
Author(s):  
Steve J. Chipera ◽  
David L. Bish
Keyword(s):  
Quantitative Analysis ◽  
Intensity Ratio ◽  
Preferred Orientation ◽  
Second Phase ◽  
Average Value ◽  
Profile Fitting ◽  
Quantitative Analyses ◽  
Peak Versus ◽  
Two Peaks ◽  
Intensity Region

Quantitative determination of phase abundances using X-ray powder diffraction is a technique in wide use today. Of the various methods employed, the Chung, or RIR method, is one of the most common because it can provide reliable results for all sample types. However, improvements can be made to the Chung method of analysis for phases which exhibit large chemical or preferred orientation effects. These effects can often be accommodated by using intensity regions that encompass several reflections, by averaging intensities from nonparallel reflections, or by using RIR values that are allowed to vary based on a predetermined functional relationship. To accommodate the effects of preferred orientation and variable composition in feldspars, RIR values versus the intensity ratio between two peaks of feldspar standards mixed with corundum have been determined. Curves of RIR have been formulated for: (1) feldspar RIR13.0−14.0° versus the intensity ratio (13.0–14.0° 2θ intensity region/27.0–28.75° 2θ intensity region); (2) feldspar RIR23.6° peak versus the intensity ratio (23.6° 2θ peak/27.0–28.75° 2θ intensity region); and (3) clinoptilolite RIR020 versus (020 reflection/22.1–23.0° 2θ intensity region). For example, RIR values for the highly variable 13.0–14.0° 2θ region for feldspar can be improved such that the quantitative results produced has a standard deviation of only 15% instead of 53% using a fixed-average value. From these curves, improved RIR values can be obtained for the quantitative analysis of unknowns. Additionally, intensity ratios can be determined between two peaks of a phase so that given the intensity of one peak, the intensity of the other peak can be readily calculated. This allows for subtraction of the intensity of a peak from one phase overlapping a peak from a second phase which is to be used for quantitative analysis but which cannot be decomposed by profile fitting.

Biomonitoring Assessment of Toxic and Trace Elements in Sterechinus neumayeri Sea Urchins from the Comandante Ferraz Station in Antarctica

2021 ◽  
Author(s):  
Mauricio Barlera Alves ◽  
Andrews Krupinski Emerenciano ◽  
Isabella Cristina Antunes da Costa Bordon ◽  
José Roberto Machado Cunha Silva ◽  
Deborah Inês Teixeira Fávaro ◽  
...  
Keyword(s):  
Trace Elements ◽  
Sea Urchins ◽  
Sterechinus Neumayeri

scholarly journals High-precision continuum rectification: Towards an Abundance Analysis of Be and Bn Stars

1994 ◽  
Vol 162 ◽  
pp. 427-428
Author(s):  
M. Kolb ◽  
D. Baade
Keyword(s):  
High Precision ◽  
New Method ◽  
Early Type ◽  
Stellar Spectra ◽  
Profile Fitting ◽  
Early Type Stars ◽  
Flux Calibration

We sketch a new method for the accurate flux calibration and normalization of stellar spectra. This is of particular importance for the analysis of rapidly rotating early–type stars. Some preliminary log g determinations by profile fitting of H γ are presented.

XRD Study of the Nacrite/CsCl/H2O Intercalation Complex

2004 ◽  
Vol 443-444 ◽  
pp. 59-64 ◽  
Author(s):  
S. Naamen ◽  
H. Ben Rhaiem ◽  
A. Ben Haj Amara
Keyword(s):  
Direct Method ◽  
Basal Spacing ◽  
X Ray Diffraction ◽  
Intercalation Complex ◽  
Xrd Pattern ◽  
X Ray ◽  
Caesium Chloride ◽  
Intercalated Compounds ◽  
Xrd Study ◽  
A Direct Method

The intercalation complex of nacrite with an alkali halide (Caesium chloride: CsCl) has been successfully prepared by mixing a CsCl saturated solution with a 8.4Å-hydrated nacrite. The homogeneous nacrite/CsCl complex has been studied by X-ray diffraction (XRD). Using an oriented clay aggregate, 10 basal reflections were obtained. The XRD pattern showed basal spacing of 10.5Å with integral series of 00l reflections indicating an ordered stacking of parallel 1:1 layers. A direct method involving a monodimensional electron density projection, along the normal to the layers, is used to determine the number and the position of intercalated compounds. The best agreement between observed and simulated p(Z) (R = 5%) is obtained by placing one Cl- ion at Z=6.7Å; one Cs+ ion at Z=8.3Å and two H O molecules at 6.3 and 7.4Å.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

High Resolution Replication of Organoclay Surfaces

1982 ◽  
Vol 40 ◽  
pp. 576-577
Author(s):  
W. W. Barker ◽  
W. E. Rigsby ◽  
V. J. Hurst ◽  
W. J. Humphreys
Keyword(s):  
Clay Mineral ◽  
Organic Molecule ◽  
Organic Molecules ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Naturally Occurring ◽  
Silicate Layers ◽  
Mineral Identification

Experimental clay mineral-organic molecule complexes long have been known and some of them have been extensively studied by X-ray diffraction methods. The organic molecules are adsorbed onto the surfaces of the clay minerals, or intercalated between the silicate layers. Natural organo-clays also are widely recognized but generally have not been well characterized. Widely used techniques for clay mineral identification involve treatment of the sample with H2 O2 or other oxidant to destroy any associated organics. This generally simplifies and intensifies the XRD pattern of the clay residue, but helps little with the characterization of the original organoclay. Adequate techniques for the direct observation of synthetic and naturally occurring organoclays are yet to be developed.

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