scholarly journals The Degree of Oxidation of Graphene Oxide

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 560
Author(s):  
Alexandra Carvalho ◽  
Mariana C. F. Costa ◽  
Valeria S. Marangoni ◽  
Pei Rou Ng ◽  
Thi Le Hang Nguyen ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Ab Initio ◽  
State Of The Art ◽  
High Accuracy ◽  
Precise Determination ◽  
Photoemission Spectroscopy ◽  
Pristine Graphene ◽  
X Ray ◽  
Degree Of Oxidation

We show that the degree of oxidation of graphene oxide (GO) can be obtained by using a combination of state-of-the-art ab initio computational modeling and X-ray photoemission spectroscopy (XPS). We show that the shift of the XPS C1s peak relative to pristine graphene, ΔEC1s, can be described with high accuracy by ΔEC1s=A(cO−cl)2+E0, where c0 is the oxygen concentration, A=52.3 eV, cl=0.122, and E0=1.22 eV. Our results demonstrate a precise determination of the oxygen content of GO samples.

scholarly journals Magnetic-Dispersive Solid Phase Extraction Based on Graphene Oxide–Fe3O4 Nanocomposites Followed by High Performance Liquid Chromatography-Fluorescence for the Preconcentration and Determination of Terazosin Hydrochloride in Human Plasma

2019 ◽  
Vol 58 (2) ◽  
pp. 178-186 ◽  
Author(s):  
Yaser Pashaei ◽  
Bahram Daraei ◽  
Maryam Shekarchi
Keyword(s):  
High Performance Liquid Chromatography ◽  
Graphene Oxide ◽  
Human Plasma ◽  
High Performance ◽  
Solid Phase ◽  
Phase Extraction ◽  
Plasma Samples ◽  
Dispersive Solid Phase Extraction ◽  
X Ray

Abstract In the present study, a facile modified impregnation method was employed to synthesize superparamagnetic graphene oxide–Fe3O4 (GO–Fe3O4) nanocomposites. Based on the GO–Fe3O4 as adsorbent, a simple and fast magnetic-dispersive solid phase extraction followed by high performance liquid chromatography with fluorescence detection (M-dSPE–HPLC–FL) method was established and validated for the preconcentration and determination of terazosin hydrochloride (TRZ) in human plasma samples. The obtained nanomaterials were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometry. Different parameters affecting the extraction efficiency, such as sample pH, amount of sorbent, extraction time, elution solvent and its volume and desorption time, were evaluated and optimized. The linearity of the proposed method was excellent over the range 0.3–50.0 ng mL−1 with an acceptable coefficient of determination (R2 = 0.9989). The limit of quantification and limit of detection were found to be 0.3 and 0.09 ng mL−1, respectively, and the preconcentration factor of 10 was achieved. Intra- and inter-day precision expressed as relative standard deviation (RSD %, n = 6) were between 2.2–3.8% and 4.7–6.4%, respectively. Accuracy, estimated by recovery assays, was 97.7–106.6% with RSD ≤ 5.2%. Ultimately, the applicability of the method was successfully confirmed by the extraction and determination of TRZ in human plasma samples.

Intraoperative Determination of the Extent of Corpus Callosotomy for Epilepsy: Two Simple Techniques

Neurosurgery ◽  
1990 ◽  
Vol 26 (1) ◽  
pp. 102-106 ◽  
Author(s):  
Issam A. Awad ◽  
Elaine Wyllie ◽  
Hans Luders ◽  
Jennifer Ahl
Keyword(s):  
Corpus Callosum ◽  
Precise Determination ◽  
Planar Geometry ◽  
Corpus Callosotomy ◽  
Midsagittal Plane ◽  
Anatomic Landmarks ◽  
Mri Scan ◽  
Simple Modification ◽  
X Ray

Abstract There is increasing interest in staged corpus callosotomy for intractable generalized epilepsy. At the first procedure, a portion (usually the anterior two-thirds) of the corpus callosum is sectioned. If seizures persist, completion of callosotomy or alternative treatment approaches can be considered. It is obviously important to ascertain that the desired extent of callosotomy was in fact accomplished at the time of initial operation. Our experience and the published literature indicate that the surgeon's impression at operation can be erroneous. We describe a technique of determining extent of corpus callosotomy during the procedure. The magnetic resonance imaging (MRI) scan in the midsagittal plane is used to select the desired extent of callosotomy. That point on the corpus callosum is characterized using simple planar geometry in relation to three anatomic landmarks in that same plane: the glabella, the inion, and the bregma (midline intersection of the coronal suture). The same point along the corpus callosum can then be located on a lateral skull xray using these same three anatomic landmarks. At surgery, an intraoperative lateral skull x-ray is obtained with a marking clip, thereby verifying the actual extent of callosotomy. We have verified the reliability of this scheme in 5 callosotomy procedures and have used this technique for intraoperative localization of midline and parasagittal targets in another 7 cases (3 tumors, 2 aneurysms, and 2 placements of interhemispheric subdural grids). In addition, we reviewed corpus callosum topography on 25 randomly selected MRI scans. A perpendicular line bisecting the glabellainion line intersects the corpus callosum at a point near its two-thirds extent in every case. This allows a quick determination of the approximate two-thirds point along the corpus callosum by skull x-ray alone, without the need of an MRI scan. The use of the new technique and its simple modification for the two-thirds callosotomy allows a precise determination of the extent of corpus callosum section at surgery and should avoid unintended deviations from the desired procedure. (Neurosurgery 26:102-106, 1990)

Ab initio structure determination of nanosized θ-KAlF4 with edge-sharing AlF6 octahedra

2009 ◽  
Vol 24 (3) ◽  
pp. 185-190 ◽  
Author(s):  
A. Le Bail
Keyword(s):  
Crystal Structure ◽  
Ab Initio ◽  
Fluorite Structure ◽  
Structure Type ◽  
Powder Diffraction Data ◽  
Orthorhombic Unit Cell ◽  
Common Edge ◽  
X Ray ◽  
Ab Initio Structure

θ-KAlF4 is a new nanosized potassium tetrafluoroaluminate metastable polymorph (13×18×55 nm3). The crystal structure is solved ab initio from X-ray powder diffraction data in direct space [orthorhombic unit cell with a=8.3242(3) Å, b=7.2502(3) Å, c=11.8875(4) Å, V=717.44(5) Å3, Z=8, and space group Pnma]. This new structure type, unique in the whole AIMIIIF4 family, is related to the fluorite structure and consists of AlF6 octahedra linked via a common edge forming a bioctahedral motif which is trans-connected through the corner-shared fluorine, resulting in the formation of infinite ladderlike double file of octahedra ([Al2F8]2−)n running along the b axis.

Ab initio structure determination of anhydrous sodium alendronate from laboratory powder X-ray diffraction data

2009 ◽  
Vol 98 (6) ◽  
pp. 2113-2121 ◽  
Author(s):  
Minakshi Asnani ◽  
K. Vyas ◽  
Apurba Bhattacharya ◽  
Surya Devarakonda ◽  
Santu Chakraborty ◽  
...  
Keyword(s):  
Ab Initio ◽  
Diffraction Data ◽  
Structure Determination ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ab Initio Structure
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