Weighted Mostar invariants of chemical compounds: An analysis of structural stability.

The concept of the weighted Mostar invariant is a mathematical tool used in chemical graph theory to study the stability of chemical compounds. Several recent studies have explored the weighted Mostar invariant of various chemical structures, including hydrocarbons, alcohols, and other organic compounds. One of the key advantages of the weighted Mostar invariant is that it can be easily computed for large and complex chemical structures, making it a valuable tool for studying the stability of a wide range of chemical compounds. This notion has been utilized to build novel approaches for forecasting chemical compound stability, such as machine learning algorithms. The focus of the paper is to demonstrate the weighted Mostar indices of three specific nanostructures: silicon dioxide (SIO2, poly-methyl methacrylate network (PMMA(s)), and melem chains (MC(h)). The authors seek to provide the findings of their investigation of these nanostructures using the weighted Mostar invariant.

Computing the Laplacian spectrum and Wiener index of pentagonal-derivation cylinder/Möbius network.

The Laplacian spectrum significantly contributes the study of the structural features of non-regular networks. Actually, it emphasizes the interaction among the network eigenvalues and their structural properties. Let Pn(Pn') represent the pentagonal-derivation cylinder (Möbius) network. In this article, based on the decomposition techniques of the Laplacian characteristic polynomial, we initially determine that the Laplacian spectra of Pn contain the eigenvalues of matrices LR and LS. Furthermore, using the relationship among the coefficients and roots of these two matrices, explicit calculations of the Kirchhoff index and spanning trees of Pn are determined. The relationship between the Wiener and Kirchhoff indices of Pn is also established.

Extremal topological indices of some nanostructures.

In this work, general formulas of degree-based and neighborhood degree sum-based topological indices for a 2D lattice of H-Naphtalenic nanotubes and pent-heptagonal nanosheets are determined. As an example, six neighborhood degree sum-based topological indices are computed using the obtained formula. Furthermore, the extremal cases of these nanostructures with a fixed number of blocks are characterized for a given degree-based or neighborhood degree sum-based topological index. Also a visual comparison of these indices is shown. Additionally, it is demonstrated how beneficial the indices are for representing structure-property relationships.

Topological Entropy Characterization, NMR and ESR Spectral Patterns of Coronene-Based Transition Metal Organic Frameworks.

Metal organic frameworks (MOFs) are topical crystalline materials with high porosity and inner surface areas synthesized from naturally occurring minerals. Such MOFs with transition metals have attracted considerable attention because of their fascinating morphological diversity and tunable characteristics. The coronene-based structural frameworks with transition metal atoms are synthesized by repeating a fixed coronene unit at several levels. In this study, topological indices and NMR and ESR spectral patterns are computed for these MOFs to shed light on their structures and spectral properties. We obtained mathematical expressions of topological indices based on degree and degree-sum values of MOFs for the rectangular, hexagonal, and parallelogram peripheral shapes. Furthermore, the entropy measures of these novel frameworks are evaluated with the help of index functionals and compared to a wide range of degree-based descriptors. The NMR and ESR spectral patterns have been obtained from the distance degree vector sequences and symmetries for the three MOFs.

Expected value of first Zagreb connection index in random cyclooctatetraene chain, random polyphenyls chain, and random chain network.

The Zagreb connection indices are the known topological descriptors of the graphs that are constructed from the connection cardinality (degree of given nodes lying at a distance 2) presented in 1972 to determine the total electron energy of the alternate hydrocarbons. For a long time, these connection indices did not receive much research attention. Ali and Trinajstic [Mol. Inform. 37, Art. No. 1800008, 2018] examined the Zagreb connection indices and found that they compared to basic Zagreb indices and that they provide a finer value for the correlation coefficient for the 13 physico-chemical characteristics of the octane isomers. This article acquires the formulae of expected values of the first Zagreb connection index of a random cyclooctatetraene chain, a random polyphenyls chain, and a random chain network with l number of octagons, hexagons, and pentagons, respectively. The article presents extreme and average values of all the above random chains concerning a set of special chains, including the meta-chain, the ortho-chain, and the para-chain.

The comparative analysis of two molecular indices in random polyphenyl and spiro chains.

Zagreb indices are well-known and historical indices that are very useful to calculate the properties of compounds. In the last few years, various kinds of Zagreb and Randic indices are investigated and defined to fulfil the demands of various engineering applications. Phenylenes are a class of conjugated hydrocarbons composed of a special arrangement of six- and four-membered rings. This special chain, produced by zeroth-order Markov process has been commonly appeared in the field of pharmacology and materials. Here, we compute the expected values of a multiplicative versions of the geometric arithmetic and atomic bond connectivity indices for these special hydrocarbons. Moreover, we make comparisons in the form of explicit formulae and numerical tables between the expected values of these indices in the random polyphenyl $ \mathbb{P}_n $ and spiro $ \mathbb{S}_n $ chains.

Diagnosing Neurally Mediated Syncope Using Classification Techniques.

Syncope is a medical condition resulting in the spontaneous transient loss of consciousness and postural tone with spontaneous recovery. The diagnosis of syncope is a challenging task, as similar types of symptoms are observed in seizures, vertigo, stroke, coma, etc. The advent of Healthcare 4.0, which facilitates the usage of artificial intelligence and big data, has been widely used for diagnosing various diseases based on past historical data. In this paper, classification-based machine learning is used to diagnose syncope based on data collected through a head-up tilt test carried out in a purely clinical setting. This work is concerned with the use of classification techniques for diagnosing neurally mediated syncope triggered by a number of neurocardiogenic or cardiac-related factors. Experimental results show the effectiveness of using classification-based machine learning techniques for an early diagnosis and proactive treatment of neurally mediated syncope.

Support Vector Machine-Based Classification of Vasovagal Syncope Using Head-Up Tilt Test.

Syncope is the medical condition of loss of consciousness triggered by the momentary cessation of blood flow to the brain. Machine learning techniques have been established to be very effective way to address such problems, where a class label is predicted for given input data. This work presents a Support Vector Machine (SVM) based classification of neuro-mediated syncope evaluated using train-test-split and K-fold cross-validation methods using the patient's physiological data collected through the Head-up Tilt Test in pure clinical settings. The performance of the model has been analyzed over standard statistical performance indices. The experimental results prove the effectiveness of using SVM-based classification for the proactive diagnosis of syncope.

The expected values of arithmetic bond connectivity and geometric indices in random phenylene chains.

Phenylenes are a class of conjugated hydrocarbons composed of a special arrangement of six- and four-membered rings. In this paper, the expected values of the atom-bond connectivity (ABC), geometric-arithmetic (GA), and Zagreb indices of this class of conjugated hydrocarbons have been determined. At the end, the comparisons with respect to the random phenylene chains among the expected values of these indices, have been determined explicitly. The graphical profiles of these indices have been shown in order to support our results.

Predictive parameters of arteriovenous fistula maturation in patients with end-stage renal disease.

BACKGROUND: The objevctive of the present study was to explore the potential influence of blood markers and patient factors such as risk factors, kidney function profile, coagulation profile, lipid profile, body mass index, blood pressure, and vein diameter on the maturation of arteriovenous fistula (AVF) in patients with end-stage renal disease. METHODS: Retrospective data from 300 patients who had undergone AVF creation at the Royal Infirmary of Edinburgh were examined. A predictive logistic regression model was developed using a backward stepwise procedure. Model performance, discrimination, and calibration were assessed using the receiver operating characteristic (ROC) curve and Hosmer-Lemeshow goodness-of-fit test. The final model was externally validated by 100 prospective patients who received a new fistula at the Royal Infirmary of Edinburgh. RESULTS: A total of 400 (300 retrospective and 100 prospective) patients were recruited for this study, with a mean age of 60.14 ± 15.9 years (development set) and 58 ± 15 years (validation set), respectively (P = 0.208). Study results showed that males were twice as likely to undergo fistula maturation as females, while patients with no evidence of peripheral vascular disease (PVD) were three times more likely to mature their fistula and a preoperative vein diameter > 2.5 mm resulted in a fivefold increase in fistula maturation as compared with a vein size of less than 2.5 mm. The model for fistula maturation had fair discrimination, as indicated by the area under the ROC curve (0.68), but good calibration as indicated by the Hosmer-Lemeshow test (P = 0.79). The area under the receiver operating curve for the validation model in the validation set was 0.59. Similarly, in the validation set, the Hosmer-Lemeshow statistic indicated an agreement between the observed and predicted probabilities of maturation (P > 0.05). CONCLUSION: Gender, PVD, and vein size are independent predictors of AVF maturation. The clinical utility of these risk categories in the maturation of AVF requires further evaluation in longer follow-up.

Aneurysms in vascular access: state of the art and future developments.

A master class was held at the Vascular Access at Charing Cross (VA@CX2017) conference in April 2017 with invited experts and active audience participation to discuss arteriovenous (AV) vascular access aneurysms, a serious and common complication of vascular access (VA). The natural history of aneurysms in VA is poorly defined, and although classifications exist they are not uniformly applied in studies or clinical practice. True and pseudo aneurysms of AV access occur. Whilst an AV fistula by definition is an abnormal dilatation of a blood vessel, an agreed definition of 18 mm, or 3 times accepted maturation diameter, is proposed. The mechanism of aneurysmal dilatation is unknown but appears to be a combination of excessive external remodeling, wall changes due to injury, and obstruction of outflow. Diagnosis of AV aneurysms is based on physical examination and ultrasound. Venography and cross-sectional imaging may assist and be required for the investigation of outflow stenosis. Treatment of pseudo aneurysms and true aneurysms of VA (AVA) is not evidence-based, but relies on clinical experience and available facilities. In many AVA, a conservative approach with surveillance is suitable, although intervals and modalities are unclear. Avoidance of rupture is imperative and preemptive treatment should aim for access preservation, ideally with avoidance of prosthetic materials. Different techniques of aneurysmorrhaphy are described with good results in published series. Although endovascular approaches and stenting are described with good short-term results, issues with cannulation of stented areas occur and, while possible, this is not recommended, and long-term access revision is recommended.

Bounds for the general sum-connectivity index of composite graphs.

The general sum-connectivity index is a molecular descriptor defined as [Formula: see text], where [Formula: see text] denotes the degree of a vertex [Formula: see text], and α is a real number. Let X be a graph; then let [Formula: see text] be the graph obtained from X by adding a new vertex [Formula: see text] corresponding to each edge of X and joining [Formula: see text] to the end vertices of the corresponding edge [Formula: see text]. In this paper we obtain the lower and upper bounds for the general sum-connectivity index of four types of graph operations involving R-graph. Additionally, we determine the bounds for the general sum-connectivity index of line graph [Formula: see text] and rooted product of graphs.

Acute aortic occlusion with sudden paraplegia secondary to Aspergillus niger embolism from Aspergillus niger aortitis.

Acute aortic occlusion caused by a saddle embolus is a rare vascular emergency. Associated sudden paraplegia secondary to spinal cord ischemia is even more uncommon. Aspergillus surgical site infection is typically linked to cardiac surgery but is exceptional. Here we present a case that combines all of these factors. A 67-year-old man presented with sudden paraplegia from acute aortic occlusion with a saddle embolus from Aspergillus niger aortitis 4 months after aortic valve replacement and aortoplasty. We believe this to be the second reported case of Aspergillus niger aortitis and the first presenting as aortic occlusion with paraplegia.

Percutaneous balloon-expandable stent graft repair of a ruptured iliac aneurysm.

Elective stent graft repair of iliac aneurysm is successful and safe. There are, however, few published data on stent grafting unstable patients with acute iliac aneurysm rupture. Iliac diameter mismatch can also present a challenge to emergency endovascular treatment. We report the treatment of an unstable patient with iliac aneurysm rupture and diameter mismatch using a percutaneous balloon-expandable polytetrafluoroethylene (PTFE) stent graft. Outcomes were satisfactory up to 12-month follow-up. Treatment of iliac aneurysm rupture using a balloon-expandable stent graft can be successful in selected patients. A percutaneous approach and targeted stent graft postdilatation enable prompt repair in the presence of diameter mismatch, facilitating emergency therapy.