scholarly journals Synthesis and study of oligohexamethyleneguanidine hydroiodide as a radiopaque substance

Author(s):  
O. S. Ochirov ◽  
S. A. Stelmakh ◽  
M. N. Grigor’eva ◽  
V. O. Okladnikova ◽  
D. M. Mognonov

Abstract: Diagnosis of complex injuries, such as splinter fractures and wounds, skull injuries accompanied by internal injuries that are inaccessible to visual control, presents the greatest difficulties during X-ray examination. Therefore, it is relevant to develop a drug that can help localize the site of a pathological lesion with high accuracy, relying only on the results of an X-ray study, which is possible when a reference point (substance) is applied to the patient’s skin. A radiopaque contrast compound based on an iodinated polymeric matrix with iodine as the contrasting component and polyguanidine as the carrier has been proposed to be used as a reference point substance. The choice of this class of polymers stemmed from the fact that a positive charge is localized to a greater extent on the carbon atom of the guanidine group, which allows loading iodine anions into it. Protonation of pure guanidine with hydroiodic acid has helped obtain guanidine hydroiodide. This finding was confirmed by IR spectroscopy methods (a decrease in the intensity of bands in the region of 1,380, 880 cm−1 in comparison with guanidine, as well as broadening of the band of stretching vibrations of amino groups characteristic of guanidine salts) and X-ray phase analysis. Polyhexamethylene guanidine hydroiodide was synthesized based on hexamethylenediamine and iodine-containing guanidine salt using melt polycondensation. The results show that the aqueous solutions of samples under study absorb X-radiation and are the X-ray-positive substances (exposure radiation dosage E = 0.04 mSV).

1998 ◽  
Vol 63 (2) ◽  
pp. 211-221 ◽  
Author(s):  
Miloš Tichý ◽  
Luděk Ridvan ◽  
Miloš Buděšínský ◽  
Jiří Závada ◽  
Jaroslav Podlaha ◽  
...  

The axially chiral bis(α-amino acid)s cis-2 and trans-2 as possible building blocks for polymeric structures of novel type of helicity were prepared. Their configuration has been determined by NMR spectroscopy and, in the case of the trans-isomer, confirmed by single-crystal X-ray diffraction. Analogous pair of stereoisomeric diacids cis-3 and trans-3, devoid of the amino groups, was also prepared and their configuration assigned. The observed differences in the NMR spectra of cis- and trans-isomers of 2 and 3 are discussed from the viewpoint of their different symmetry properties.


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 ◽  
...  

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.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ryoya Shiode ◽  
Mototaka Kabashima ◽  
Yuta Hiasa ◽  
Kunihiro Oka ◽  
Tsuyoshi Murase ◽  
...  

AbstractThe purpose of the study was to develop a deep learning network for estimating and constructing highly accurate 3D bone models directly from actual X-ray images and to verify its accuracy. The data used were 173 computed tomography (CT) images and 105 actual X-ray images of a healthy wrist joint. To compensate for the small size of the dataset, digitally reconstructed radiography (DRR) images generated from CT were used as training data instead of actual X-ray images. The DRR-like images were generated from actual X-ray images in the test and adapted to the network, and high-accuracy estimation of a 3D bone model from a small data set was possible. The 3D shape of the radius and ulna were estimated from actual X-ray images with accuracies of 1.05 ± 0.36 and 1.45 ± 0.41 mm, respectively.


Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2949
Author(s):  
Marzieh Rabiei ◽  
Arvydas Palevicius ◽  
Amir Dashti ◽  
Sohrab Nasiri ◽  
Ahmad Monshi ◽  
...  

Taking into account X-ray diffraction, one of the well-known methods for calculating the stress-strain of crystals is Williamson-Hall (W–H). The W-H method has three models, namely (1) Uniform deformation model (UDM); (2) Uniform stress deformation model (USDM); and (3) Uniform deformation energy density model (UDEDM). The USDM and UDEDM models are directly related to the modulus of elasticity (E). Young’s modulus is a key parameter in engineering design and materials development. Young’s modulus is considered in USDM and UDEDM models, but in all previous studies, researchers used the average values of Young’s modulus or they calculated Young’s modulus only for a sharp peak of an XRD pattern or they extracted Young’s modulus from the literature. Therefore, these values are not representative of all peaks derived from X-ray diffraction; as a result, these values are not estimated with high accuracy. Nevertheless, in the current study, the W-H method is used considering the all diffracted planes of the unit cell and super cells (2 × 2 × 2) of Hydroxyapatite (HA), and a new method with the high accuracy of the W-H method in the USDM model is presented to calculate stress (σ) and strain (ε). The accounting for the planar density of atoms is the novelty of this work. Furthermore, the ultrasonic pulse-echo test is performed for the validation of the novelty assumptions.


2011 ◽  
Vol 89 (8) ◽  
pp. 971-977
Author(s):  
Danielle M. Chisholm ◽  
Robert McDonald ◽  
J. Scott McIndoe

Methylation of aromatic amino groups is usually straightforward, but the formation of two intramolecular hydrogen bonds in 3,3′-N,N′-bis(amino)-2,2′-bipyridine and (or) the potential for ring methylation prevents the clean tetramethylation of this molecule. Numerous attempts to make 3,3′-N,N′-bis(dimethylamino)-2,2′-bipyridine produced only complex mixtures of variously methylated products, and the only isolated molecule was 3,3′-N,N′-bis(methylamino)-2,2′-bipyridine, for which an X-ray crystal structure was obtained.


1994 ◽  
Vol 47 (12) ◽  
pp. 2221 ◽  
Author(s):  
MJ Crossley ◽  
SR Davies ◽  
TW Hambley

Bromohydrination of benzyl (1RS,2SR,4SR)-2-benzyloxycarbonylamino-1-trimethylsilyloxy-bicyclo[2.2.2]oct-5-ene-2-carboxylate (6a) and the (1RS,2RS,4SR)- diastereomer (6b) with N- bromoacetamide in aqueous dioxan has been investigated. These reactions are highly regio-and stereo-selective and give the corresponding bromohydrins (9a) and (9b), but in moderate to low yield. These bromohydrins have the necessary stereochemistry for conversion into anticapsin. The other products from the reaction are tricyclic compounds formed by capture of the anti- bromonium cation intermediates or resultant bromohydrins by interaction with the proximal protected carboxy and amino groups within the molecules. Thus the carbolactone (11) is formed from the endo -adduct (6a), and the carbonimidic acid derivative (12) and the cyclic urethane (13) are formed from the exo-adduct (6b). Cleavage of the trimethylsilyl group from the tricyclic compound (12) gives benzyl (1RS,2RS,3RS,7RS,8RS)-5-benzyloxy-2-bromo-8-hydroxy-4-oxa-6-azatricyclo[5.3.1.03,8]undec-5-ene-7-carboxylate(14), the structure of which was determined by X-ray diffraction methods and refined to a residual of 0.035 for 1549 independent observed reflections. The crystals of (14) are monoclinic, P21/c, a 12.954(3), b 6.197(3), c 26.784(7) Ǻ, β 95.33(2)°, Z 4. Reactions attempting to generate iodohydrins from the alkenes (6) were also highly regioselective and gave detrimethylsilylated iodo analogues of (11) and (13).


Mathematics ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1002
Author(s):  
Mohammad Khishe ◽  
Fabio Caraffini ◽  
Stefan Kuhn

This article proposes a framework that automatically designs classifiers for the early detection of COVID-19 from chest X-ray images. To do this, our approach repeatedly makes use of a heuristic for optimisation to efficiently find the best combination of the hyperparameters of a convolutional deep learning model. The framework starts with optimising a basic convolutional neural network which represents the starting point for the evolution process. Subsequently, at most two additional convolutional layers are added, at a time, to the previous convolutional structure as a result of a further optimisation phase. Each performed phase maximises the the accuracy of the system, thus requiring training and assessment of the new model, which gets gradually deeper, with relevant COVID-19 chest X-ray images. This iterative process ends when no improvement, in terms of accuracy, is recorded. Hence, the proposed method evolves the most performing network with the minimum number of convolutional layers. In this light, we simultaneously achieve high accuracy while minimising the presence of redundant layers to guarantee a fast but reliable model. Our results show that the proposed implementation of such a framework achieves accuracy up to 99.11%, thus being particularly suitable for the early detection of COVID-19.


1995 ◽  
Vol 50 (4-5) ◽  
pp. 381-387 ◽  
Author(s):  
Jürgen Kintrup ◽  
Harald Züchner

Abstract X-ray photoelectron spectroscopy (XPS) has been carried out to study the reaction of differently prepared palladium samples (solid and film Pd) with atmospheric oxygen. A careful curve fitting of the measured Pd-3d5/2 peak allows to separate the Pd-3d5/2 peak for Pd in surface PdO from the dominant Pd-3d5/2 peak of the non-oxidized bulk palladium and to determine the chemical shift of the "oxidized" Pa line with high accuracy. Differences in the chemical shifts for the surface PdO on solid and film palladium are explained by a different charging caused by the photoelectric effect in XPS measurements. The smaller charging effect observed for film palladium as compared to solid palladium indicates a stronger oxygen bonding to the (rougher) film palladium. The strong Pd-O bonding seems to be an essential reason for the reduced hydrogen-permeability of film palladium compared to solid palladium


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