Journal of Mathematical Chemistry最新文献_第8页

In vivo brain MRS at a 1.5T clinical scanner: Optimized derivative fast Fourier transform for high-resolution spectra from time signals encoded with and without water suppression 在 1.5T 临床扫描仪上进行活体脑 MRS 扫描：优化衍生快速傅立叶变换，从有水抑制和无水抑制的时间信号编码中获得高分辨率光谱

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-22 DOI: 10.1007/s10910-024-01597-6

Dževad Belkić, Karen Belkić

{"title":"In vivo brain MRS at a 1.5T clinical scanner: Optimized derivative fast Fourier transform for high-resolution spectra from time signals encoded with and without water suppression","authors":"Dževad Belkić, Karen Belkić","doi":"10.1007/s10910-024-01597-6","DOIUrl":"10.1007/s10910-024-01597-6","url":null,"abstract":"<div><p>We study single-voxel in vivo proton magnetic resonance spectroscopy (MRS) of white matter in the brain of a 25 year old healthy male volunteer. The free induction decay (FID) data of short length (0.5KB) are encoded at a long echo time (272 ms) with and without water suppression at a clinical scanner of a weak magnetic field (1.5T). For these FIDs, the fast Fourier transform (FFT) gives sparse, rough and metabolically uninformative spectra. In such spectra, resolution and signal to noise ratio (SNR) are poor. Exponential or Gaussian filters applied to the FIDs can improve SNR in the FFT spectra, but only at the expense of the worsened resolution. This impacts adversely on in vivo MRS for which both resolution and SNR of spectra need to be very good or excellent, without necessarily resorting to stronger magnetic fields. Such a long sought goal is at last within reach by means of the optimized derivative fast Fourier transform (dFFT), which dramatically outperforms the FFT in every facet of signal estimations. The optimized dFFT simultaneously improves resolution and SNR in derivative spectra. They are presently shown to be of comparably high quality irrespective of whether water is suppressed or not in the course of FID encodings. The ensuing benefits of utmost relevance in the clinic include a substantial shortening of the patient examination time. The implied significantly better cost-effectiveness should make in vivo MRS at low-field clinical scanners (1.5T) more affordable to ever larger circles of hospitals worldwide.</p></div>","PeriodicalId":648,"journal":{"name":"Journal of Mathematical Chemistry","volume":"62 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10910-024-01597-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140198839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

On the thermal properties of pure and defective Ψ-graphene nanotubes by molecular dynamics simulations 通过分子动力学模拟研究纯Ψ-石墨烯纳米管和缺陷Ψ-石墨烯纳米管的热特性

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-21 DOI: 10.1007/s10910-024-01588-7

Pingfang Yuan, Zhenfeng Liu, Yanxin Xie, Yafei Meng, Mengdie Li, Keke Chen

引用次数: 0

Numerical approach for time-fractional Burgers’ equation via a combination of Adams–Moulton and linearized technique 结合亚当斯-莫尔顿和线性化技术的时间分数布尔格斯方程数值方法

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-18 DOI: 10.1007/s10910-024-01589-6

Yonghyeon Jeon, Sunyoung Bu

引用次数: 0

Improved rotating Kratzer–Fues oscillator: eigenenergies, eigenfunctions, coherent states and ladder operators 改进的旋转克拉策-福斯振荡器：特征能、特征函数、相干态和梯形算子

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-16 DOI: 10.1007/s10910-024-01585-w

Marcin Molski

引用次数: 0

Correction: Why are the local hyper-softness and the local softness more appropriate local reactivity descriptors than the dual descriptor and the Fukui function, respectively? 更正：为什么局部超软度和局部软度分别比对偶描述符和福井函数更适合作为局部反应性描述符？

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-15 DOI: 10.1007/s10910-024-01613-9

Jorge I. Martínez-Araya

引用次数: 0

Efficient approximation of solution derivatives for system of singularly perturbed time-dependent convection-diffusion PDEs on Shishkin mesh Shishkin 网格上奇异扰动时变对流扩散 PDE 系统求解导数的高效近似方法

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-14 DOI: 10.1007/s10910-024-01587-8

Sonu Bose, Kaushik Mukherjee

{"title":"Efficient approximation of solution derivatives for system of singularly perturbed time-dependent convection-diffusion PDEs on Shishkin mesh","authors":"Sonu Bose, Kaushik Mukherjee","doi":"10.1007/s10910-024-01587-8","DOIUrl":"10.1007/s10910-024-01587-8","url":null,"abstract":"<div><p>This article deals with a coupled system of singularly perturbed convection-diffusion parabolic partial differential equations (PDEs) possessing overlapping boundary layers. As the thickness of the layer shrinks for small diffusion parameter, efficient capturing of the solution and the diffusive flux (<i>i</i>.<i>e</i>., scaled first-order spatial derivative of the solution) leads to a difficult task. It is well-known that the classical numerical techniques have deficiencies in estimating the solution and the diffusive flux on equidistant mesh unless the mesh-size is adequately large. We aim to generate an efficient numerical approximation to the coupled system of PDEs by employing the implicit-Euler method in time and a classical finite difference scheme in space on a layer-adapted Shishkin mesh. Firstly, we discuss about parameter-uniform convergence of the numerical solution in <span>(C^0)</span>-norm followed by the error analysis for the scaled discrete space derivative and the discrete time derivative. Subsequently, the parameter-uniform error bound is established in weighted <span>(C^1)</span>-norm for global approximation to the solution and the space-time solution derivatives. The theoretical findings are verified by generating the numerical results for two test examples.</p></div>","PeriodicalId":648,"journal":{"name":"Journal of Mathematical Chemistry","volume":"62 5","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10910-024-01587-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140151448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Fourth-order energy-preserving time integrator for solving the sine-Gordon equation 用于求解正弦-戈登方程的四阶能量守恒时间积分器

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-14 DOI: 10.1007/s10910-024-01586-9

Bo Jiang, Changna Lu, Yonglei Fang

引用次数: 0

Isomer number patterns in aromatic hydrocarbon chemistry: the numbers speak for themselves 芳香烃化学中的同分异构体数量模式：数字说话

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-14 DOI: 10.1007/s10910-024-01579-8

Jerry Ray Dias

引用次数: 0

Bonding alkane attributes with topological indices: a statistical intervention 用拓扑指数键合烷烃属性：统计干预

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-10 DOI: 10.1007/s10910-024-01584-x

Nadar Jenita Mary Masilamani Raja, A. Anuradha

{"title":"Bonding alkane attributes with topological indices: a statistical intervention","authors":"Nadar Jenita Mary Masilamani Raja, A. Anuradha","doi":"10.1007/s10910-024-01584-x","DOIUrl":"10.1007/s10910-024-01584-x","url":null,"abstract":"<div><p>This research delves into a comprehensive investigation of a specific group of alkanes, with the primary objective of establishing meaningful associations between their inherent physical attributes and a set of graphical parameters ranging from topological indices to their associated graphical entropies. Though there are countless techniques to relate molecular structure and physical properties of chemical compounds, the pursuit has often been pricey and arduous. With a view to curb the expense and intense labour, this work focuses on attaining some of these properties using graphical interpretations and statistical interventions. Driven by this objective, we compute Sombor index, a recently developed topological tool and some of its variants for all structural isomers of alkanes with carbon range four to nine. Furthermore, our study employs multiple regression analysis to explore their connections with some physical attributes of alkanes while concurrently addressing the challenge posed by multicollinearity. We have adopted the technique of robust regression to scale down the impact of outliers in the dataset, while generating regression models. Further, the established results are justified with a 10-fold cross validation process and a comparison with the results obtained from different topological indices. The results of this research contribute a valuable insight to the fields of chemical informatics and structural analysis, offering an enhanced comprehension of the interplay between molecular structure and physical attributes within alkanes.</p></div>","PeriodicalId":648,"journal":{"name":"Journal of Mathematical Chemistry","volume":"62 10","pages":"2889 - 2911"},"PeriodicalIF":1.7,"publicationDate":"2024-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140098349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Adaptive second derivative multistep methods for solving stiff chemical problems 解决僵化化学问题的自适应二阶导数多步法

IF 1.7 3区化学

Journal of Mathematical Chemistry Pub Date : 2024-03-08 DOI: 10.1007/s10910-024-01582-z

Mozhgan Eghbaljoo, Gholamreza Hojjati, Ali Abdi

引用次数: 0