A descent Dai-Liao conjugate gradient method for nonlinear equations

Numerical Algorithms - In this work, we propose an algorithm for solving system of nonlinear equations. The idea is a combination of the descent Dai-Liao method by Babaie-Kafaki and Gambari (Optim....     

Inside Cover: Parahydrogen-Induced Carbon-13 Radiofrequency Amplification by Stimulated Emission of Radiation (Angew. Chem. Int. Ed. 5/2023)

The feasibility of Carbon-13 Radiofrequency (RF) Amplification by Stimulated Emission of Radiation (C-13 RASER) is demonstrated on a bolus of liquid hyperpolarized ethyl [1-¹³C]acetate. Hyperpolarized ethyl [1-¹³C]acetate was prepared via pairwise addition of parahydrogen to vinyl [1-¹³C]acetate and polarization transfer from nascent parahydrogen-derived protons to the carbon-13 nucleus via magnetic field cycling yielding C-13 nuclear spin polarization of approximately 6 %. RASER signals were detected from samples with concentration ranging from 0.12 to 1 M concentration using a non-cryogenic 1.4T NMR spectrometer equipped with a radio-frequency detection coil with a quality factor (Q) of 32 without any modifications. C-13 RASER signals were observed for several minutes on a single bolus of hyperpolarized substrate to achieve 21 mHz NMR linewidths. The feasibility of creating long-lasting C-13 RASER on biomolecular carriers opens a wide range of new opportunities for the rapidly expanding field of C-13 magnetic resonance hyperpolarization.     

Functionalization of zeolite ZSM-5 by hydrosilylation and acetone coupling: synthesis, MAS NMR, and theory

We report a two-step postsynthetic functionalization reaction of zeolite HZSM-5 that proceeds with high selectivity at room temperature. In the first step the framework acid sites of the zeolite are reacted with phenylsilane to replace the acidic proton with a hydrosilyl (-SiH3) group covalently linked to the framework. This group readily couples to acetone in a second step to form a framework-bound hydrosilyl isopropyl ether that is thermally stable at 473 K, but decomposes in the presence of moisture. We characterized these reactions using 29Si, 1H, and 13C MAS NMR, as appropriate. Theoretical modeling using density functional theory and cluster models of the zeolite acid site confirmed that both steps were exothermic and provided theoretical chemical shift values in excellent agreement with experiment.     

小型二氧化钛团簇(TiO2)n (n=2-8)的低能异构体研究

钛和氧之间存在多种成键方式,但迄今为止,二氧化钛团簇均只有少数几种异构体被报道. 与广泛使用的全局优化方法不同,本工作通过优化大量的随机初始结构,获得(TiO₂)_n (n=2-8)团簇稳定异构体. 首先利用PM6半经验方法对高达一万个以上的初始结构进行初步的优化筛选,并对筛选出的结构进行进一步的DFT计算以获得二氧化钛团簇的稳定异构体. 利用这种策略,发现了大量未经报道的稳定异构体,并提出了(TiO₂)₅和(TiO₂)₈新的最稳定异构体. 这些结构中包括含3个末端氧原子的异构体、含5配位氧原子和6配位钛原子的异构体等未经报道的新结构类型. 与丰富成键特征相对应,发现异构体数目随团簇尺寸的增大而急剧增加,对于(TiO₂)₇和(TiO₂)₈,能量在30 kcal/mol以内的异构体都在50个以上. 该工作发现了大量的二氧化钛小型团簇异构体,并凸显了其多样的结构特征,增进了对二氧化钛纳米团簇的结构、成键的理解,并为进一步的理论模拟、力场优化等提供了理论基础.     

Contrast source inversion methods in elastodynamics

In this paper a nonlinear inversion method is presented for determining the mass density of an elastic inclusion from the knowledge of how the inclusion scatters known incident elastic waves. The algorithm employed is an extension of the multiplicative regularized contrast source inversion method (MR-CSI) to elasticity. This method involves alternate determination of the mass density contrast and the contrast sources (the product of the contrast and the fields) in each iterative step. The simple updating schemes of the method allow the introduction of an extra regularization term to the cost functional as a multiplicative constraint. This so-called MR-CSI method (MR-CSI) has been proven to be very effective for the acoustic and electromagnetic inverse scattering problems. Numerical examples demonstrate that the MR-CSI method shows excellent edge preserving properties by robustly handling noisy data very well, even for more complicated elastodynamic problems.     

Magnetoelastic vibration of a plate

Summary The propagation of plane harmonic waves in a thin flat homogeneous isotropic plate of finite width and infinite length permeated by a constant magnetic field is examined. The frequency equations corresponding to the symmetric and antisymmetric modes of vibration of the plate are obtained, and some limiting cases of the frequency equations are then discussed.     

Phloroglucinol as a Potential Candidate against Trypanosoma congolense Infection: Insights from In Vivo,In Vitro,Molecular Docking and Molecular Dynamic Simulation Analyses

Sub-Saharan Africa is profoundly challenged with African Animal Trypanosomiasis and the available trypanocides are faced with drawbacks, necessitating the search for novel agents. Herein, the chemotherapeutic potential of phloroglucinol on T. congolense infection and its inhibitory effects on the partially purified T. congolense sialidase and phospholipase A₂ (PLA₂) were investigated. Treatment with phloroglucinol for 14 days significantly (p < 0.05) suppressed T. congolense proliferation, increased animal survival and ameliorated anemia induced by the parasite. Using biochemical and histopathological analyses, phloroglucinol was found to prevent renal damages and splenomegaly, besides its protection against T. congolense-associated increase in free serum sialic acids in infected animals. Moreover, the compound inhibited bloodstream T. congolense sialidase via mixed inhibition pattern with inhibition binding constant (Ki) of 0.181 µM, but a very low uncompetitive inhibitory effects against PLA₂ (Ki > 9000 µM) was recorded. Molecular docking studies revealed binding energies of −4.9 and −5.3 kcal/mol between phloroglucinol with modeled sialidase and PLA₂ respectively, while a 50 ns molecular dynamics simulation using GROMACS revealed the sialidase-phloroglucinol complex to be more compact and stable with higher free binding energy (−67.84 ± 0.50 kJ/mol) than PLA₂-phloroglucinol complex (−77.17 ± 0.52 kJ/mol), based on MM-PBSA analysis. The sialidase-phloroglucinol complex had a single hydrogen bond interaction with Ser453 while none was observed for the PLA₂-phloroglucinol complex. In conclusion, phloroglucinol showed moderate trypanostatic activity with great potential in ameliorating some of the parasite-induced pathologies and its anti-anemic effects might be linked to inhibition of sialidase rather than PLA₂.     

Comparative G-Protein-Coupled Estrogen Receptor (GPER) Systems in Diabetic and Cancer Conditions: A Review

For many patients, diabetes Mellitus and Malignancy are frequently encountered comorbidities. Diabetes affects approximately 10.5% of the global population, while malignancy accounts for 29.4 million cases each year. These troubling statistics indicate that current treatment approaches for these diseases are insufficient. Alternative therapeutic strategies that consider unique signaling pathways in diabetic and malignancy patients could provide improved therapeutic outcomes. The G-protein-coupled estrogen receptor (GPER) is receiving attention for its role in disease pathogenesis and treatment outcomes. This review aims to critically examine GPER’ s comparative role in diabetes mellitus and malignancy, identify research gaps that need to be filled, and highlight GPER’s potential as a therapeutic target for diabetes and malignancy management. There is a scarcity of data on GPER expression patterns in diabetic models; however, for diabetes mellitus, altered expression of transport and signaling proteins has been linked to GPER signaling. In contrast, GPER expression in various malignancy types appears to be complex and debatable at the moment. Current data show inconclusive patterns of GPER expression in various malignancies, with some indicating upregulation and others demonstrating downregulation. Further research should be conducted to investigate GPER expression patterns and their relationship with signaling pathways in diabetes mellitus and various malignancies. We conclude that GPER has therapeutic potential for chronic diseases such as diabetes mellitus and malignancy.     

Nanomaterials‐based Electrochemical Sensing of Cardiac Biomarkers for Acute Myocardial Infarction: Recent Progress

The development of the methods for early and accurate diagnosis of acute myocardial infarction are needed to facilitate immediate treatment of patients. One of the ways to achieve that is the detection of cardiac biomarkers for myocardial infarction, such as thrombin, cardiac troponins (I and T), myoglobin, etc. Nanotechnology has played an important role in the development of sensitive and efficient electrochemical sensors for cardiac biomarkers. In this review, we discuss recent progress on nanomaterial‐based electrochemical sensing of various cardiac biomarkers for acute myocardial infarction.     

Health and ecological hazards due to natural radioactivity in soil from mining areas of Nasarawa State,Nigeria

Nasarawa State is located in north central Nigeria and it is known as Nigeria's home of solid minerals. It is endowed with barite, copper, zinc, tantalite and granite. Continuous releases of mining waste and tailings into the biosphere may result in a build-up of radionuclides in air, water and soil. This work therefore aims to measure the activity concentration levels of primordial radionuclides in the soil/sediment samples collected from selected mines of the mining areas of Nasarawa State. The paper also assesses the radiological and radio ecological impacts of mining activities on the residents of mining areas and their environment. The activity concentrations of primordial radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K) in the surface soils/sediment samples were determined using sodium iodide-thallium gamma spectroscopy. Seven major mines were considered with 21 samples taken from each of the mines for radiochemistry analysis. The human health hazard assessment was conducted using regulatory methodologies set by the United Nations Scientific Committee on the Effects of Atomic Radiation, while the radio ecological impact assessment was conducted using the ERICA tool v. 1.2. The result shows that the activity concentrations of ⁴⁰K in the water ways of the Akiri copper and the Azara barite mines are 60 and 67?% higher than the world average value for ⁴⁰K, respectively. In all mines, the annual effective dose rates (mSv y^?1) were less than unity, and a maximum annual gonadal dose of 0.58 mSv y^?1 is received at the Akiri copper mine, which is almost twice the world average value for gonadal dose. The external hazard indices for all the mines were less than unity. Our results also show that mollusc-gastropod, insect larvae, mollusc-bivalve and zooplankton are the freshwater biotas with the highest dose rates ranging from 5 to 7 µGy h^?1. These higher dose rates could be associated with zinc and copper mining at Abuni and Akiri, respectively. The most exposed terrestrial reference organisms are lichen and bryophytes. In all cases, the radio ecological risks are not likely to be discernible. This paper presents a pioneer data for ecological risk from ionizing contaminants due to mining activity in Nasarawa State, Nigeria. Its methodology could be adopted for future work on radioecology of mining.