Nuclear Magnetic Resonance Analysis Research Articles

Volatile and thermally stable tungsten organometallic complexes (RCp)W(CO)2(η3-2-tert-butylallyl) as potential thin film deposition precursor

Two organometallic tungsten complexes (RCp)W(CO)2(η3-2-tert-butylallyl) (R = methyl or ethyl, Cp = cyclopentadienyl) as precursors capable of growing tungsten-containing thin films, are constructed bearing heteroleptic ligand system. The syntheses adopt a rationally designed approach excluding the use of extreme conditions and involving facile purification procedures. The two complexes are authenticated by nuclear magnetic resonance (NMR) and elemental analysis, as well as Fourier transform-infrared (FT-IR) spectroscopy. Thermal property evaluations, including thermogravimetric and vapor pressure tests, reveal favorable thermal stability and volatility which are essential for a typical ALD process. It is noteworthy that both precursors possess relatively low-melting point and specifically, the one bearing ethyl-Cp group is in liquid phase at room temperature. Such design concept of heteroleptic ligand system and substructure tuning pave the way to develop liquid precursors which are imperative demand in microelectronic industry.

Preparation of a salt-responsive zwitterionic hydrophobically associating polymer and its application in a saturated sodium chloride drilling fluid

Conventional drilling fluid viscosity enhancers have poor anti-temperature and anti-salt properties, making it difficult to regulate the rheological properties of drilling fluids in the high-temperature, high-mineralisation environment of deep formations, which is prone to causing downhole accidents such as stuck drills and well-wall instability. In the present study, a salt-responsive amphiphilic hydrophobically attached polymer (PAADS) was synthesised by free-radical micellar polymerisation and used as a viscosity builder for saturated sodium chloride drilling fluids. The molecular structure and thermal stability were characterised by Fourier transform infrared spectroscopy, nuclear magnetic resonance and thermogravimetric analysis. The results reveal that the molecular structure of PAADS is consistent with the expected target and has good thermal stability. The viscosity-increasing performance of PAADS in a saturated sodium chloride drilling fluid was evaluated according to the American Petroleum Institute standard. PAADS can effectively maintain the rheological performance of the drilling fluid under high-temperature and high-salt conditions, and the apparent viscosity retention rate of the saturated sodium chloride drilling fluid containing 2 wt% PAADS can be up to 47.5% after 180 °C hot rolling. NaCl exhibits significant salt-responsive properties by affecting the hydrodynamic radius of PAADS molecules. In addition, PAADS solutions exhibit excellent shear dilution, viscoelasticity and stable internal space structure. This study provides new ideas for salt-resistant drilling fluid additives, which are of great significance for the efficient development of deep oil and gas resources.

Anti‐Biofilm and Anti‐Virulence Potential of 2‐Amino‐1,3,4‐Thiadiazole Derivatives

AbstractBiofilms are microbial communities that facilitate the pathogenesis of life‐threatening microbial infections through the glazing of mucosal surfaces or implanted devices thus protecting them from medications and increasing mortality rates. To discover a new class of antibiofilm agents 2‐amino‐1,3,4 thiadiazoles hybridized with pharmacologically active heterocycles were designed and synthesized. The compounds were characterized by infrared, nuclear magnetic resonance, mass spectroscopy and elemental analysis. All the compounds were assessed for their anti‐biofilm and anti‐virulence activity against P. aeruginosa and S. aureus. Quinoline‐substituted thiadiazoles were found to possess potent anti‐biofilm activity against P. aeruginosa and S. aureus. The molecular docking analysis further confirms the antibiofilm potential of the compounds. Density functional theory studies were carried out to investigate the electronic and molecular properties of the most active hybrids.

Synthesis of new analogs of N-substituted(benzoylamino)-1,2,3,6-tetrahydropyridines

Abstract The tetrahydropyridine (THP) moiety is notably present in synthetic and natural products, playing a cardinal role in the food, cosmetic, and pharmaceutical industries. The THP structure is an instrumental constituent and is widely found in alkaloids that have therapeutic properties against inflammation, cancer, the nervous system, and bacterial infections. The use of THPs has gained traction, so it is imperative to increase the structural database through the synthesis of THP derivatives. The focus of this study is to make structural modifications to the benzene ring portion of the lead compound while keeping the pyridine ring constant. Eleven novel THP analogs were synthesized using a four-step synthetic approach involving partial reduction of N-substituted ylides into 1,2,3,6-THPs. The results illustrate that 11 THPs were successfully synthesized in low to moderate yields. Flash chromatography was utilized for purification. Proton nuclear magnetic resonance, deuterium oxide exchange, carbon nuclear magnetic resonance, infrared spectroscopy, and CHN elemental analysis were utilized to characterize the THP analogs. This study aids in contributing knowledge to the THP database.

Formation of Ti3AlC2 MAX phase in the Ti–Al–C system with B2O3 additive

The main stages of the formation of the Ti3AlC2 in the Ti–Al–C system and the effect of the low-melting additive B2O3 on the yield of the MAX phase were studied by the 13C, 27Al and 47,49Ti Nuclear Magnetic Resonance (NMR) and XRD analysis. The B2O3 addition reduces the synthesis temperature of the MAX phase to 1435 °C. However, the maximum yield of the MAX phase is only ∼72 wt%. NMR spectra for the samples synthesized under non-optimal conditions for the MAX phase formation show the presence of the TiC carbide and aluminium in the metallic state. Both XRD and NMR ways affirm that the borates formation in all samples changes the fraction of aluminium engaged in the MAX phase synthesis and, as a result, reduces the MAX phase yield prepared using B2O3.

Mandarin Variety Significantly Affects the Metabolites Present in the Leaves

Late-season varieties of mandarin (Citrus reticulata Blanco) have a high economic value, so their study, characterization, and comparison among different commercial varieties is of great interest for agriculture. Detailed metabolomic analysis of mandarin leaves can provide valuable information on agronomic characteristics, vegetative development, and tree response to abiotic and biotic stresses. In this study, an analysis of the main metabolites presents in the leaves of three late-season mandarin orange varieties (‘Afourer’, ‘Orri’ and ‘Tango’), cultivated under homogeneous conditions, was carried out using nuclear magnetic resonance (1H NMR) and multivariate statistical analysis techniques. The results show that organic acids and sugars are the metabolites with the highest presence in mandarin leaves, especially malate and sucrose. Ten amino acids and other metabolites such as choline and trigonelline were also detected. Metabolites such as asparagine and isoleucine were widely implicated in the metabolic pathways of the detected compounds. The ‘Orri’ variety showed significantly more differences in metabolite concentrations compared to the other two varieties studied. Malate and sucrose were shown to be the metabolites with the greatest significant differences between the varieties compared. From an agronomic point of view, the ‘Orri’ variety differs from the other two varieties because it has concentrations of metabolites that provide good resistance to abiotic and biotic stresses and fruits of higher quality and sweetness.

Porous Ceramic Metal‐Based Flow Battery Composite Membrane

AbstractIn metal‐based flow battery, membranes significantly impact energy conversion efficiency and security. Unfortunately, damages to the membrane occur due to gradual accumulation of metal dendrites, causing short circuits and shortening cycle life. Herein, we developed a rigid hierarchical porous ceramic flow battery composite membrane with a sub‐10‐nm‐thick polyelectrolyte coating to achieve high ion selectivity and conductivity, to restrain dendrite, and to realize long cycle life and high areal capacity. An aqueous zinc‐iron flow battery prepared using this membrane achieved an outstanding energy efficiency of >80%, exhibiting excellent long‐term stability (over 1000 h) and extremely high areal capacity (260 mAh cm−2). Low‐field nuclear magnetic resonance (NMR) spectroscopy, small‐angle X‐ray scattering, in situ infrared spectroscopy, solid‐state NMR analysis, and nano‐computed tomography revealed that the rigid hierarchical pore structures and numerous hydrogen bonding networks in the membrane contributed to the stable operation and superior battery performance. This study contributes to the development of next‐generation metal‐based flow battery membranes for energy and power generation.

Key phytochemicals contributing to the bitterness of quinoa

Despite its nutritional components and potential health benefits, the bitterness of quinoa seed limits its utilization in the food industry. Saponins are believed to be the main cause of the bitterness, but it is still uncertain which specific compound is responsible. This study aimed to isolate the main components contributing to the bitterness in quinoa seed by solvent extraction and various column chromatography techniques guided by sensory evaluation. Five compounds were identified by mass spectrometry and nuclear magnetic resonance analyses, with the dose-over-threshold factors from 29.03 to 198.89. The results confirmed that triterpenoids are responsible for the bitter taste in quinoa seed, with phytolaccagenic acid derivatives being the primary contributor. Additionally, kaempferol 3-O-(2″, 6″-di-O-α-rhamnopyranosyl)-β-galactopyranoside (namely mauritianin), was demonstrated for the first time to be associated with the bitterness of quinoa. This study could provide new insight into the bitter compound identification in quinoa.

Porous Ceramic Metal-Based Flow Battery Composite Membrane.

In metal-based flow battery, membranes significantly impact energy conversion efficiency and security. Unfortunately, damages to the membrane occur due to gradual accumulation of metal dendrites, causing short circuits and shortening cycle life. Herein, we developed a rigid hierarchical porous ceramic flow battery composite membrane with a sub-10-nm-thick polyelectrolyte coating to achieve high ion selectivity and conductivity, to restrain dendrite, and to realize long cycle life and high areal capacity. An aqueous zinc-iron flow battery prepared using this membrane achieved an outstanding energy efficiency of >80%, exhibiting excellent long-term stability (over 1000 h) and extremely high areal capacity (260 mAh cm-2). Low-field nuclear magnetic resonance (NMR) spectroscopy, small-angle X-ray scattering, in situ infrared spectroscopy, solid-state NMR analysis, and nano-computed tomography revealed that the rigid hierarchical pore structures and numerous hydrogen bonding networks in the membrane contributed to the stable operation and superior battery performance. This study contributes to the development of next-generation metal-based flow battery membranes for energy and power generation.

Influences of lithofacies on fluid mobility in mixed sedimentary rocks: Insights from NMR analysis of the middle Permian Lucaogou Formation, Junggar Basin

The multi-source mixed sedimentation resulted in a unique series of mixed fine-grained sedimentary rocks evolved within the Permian Lucaogou Formation in the Jimusar Sag, located in the southeastern Junggar Basin, China. The variety of lithofacies within this series resulted in pronounced heterogeneity of pore structures, complicating the analysis of fluid occurrence space and state within reservoirs. As a result, the impact of lithofacies on fluid mobility remains ambiguous. In this study, we employed qualitative methods, such as field emission scanning electron microscopy (FE-SEM) and thin section observation, and quantitative analyses, including X-ray diffraction (XRD), total organic carbon (TOC), vitrinite reflectance (Ro), high-pressure mercury intrusion (HPMI) porosimetry, and nuclear magnetic resonance (NMR), along with linear and grey correlation analyses. This approach helped delineate the effective pore characteristics and principal factors influencing movable fluids in the fine-grained mixed rocks of the Lucaogou Formation in the Jimusar Sag, Junggar Basin. The findings indicate the development of three fundamental lithologies within the Lucaogou Formation: fine sandstone, siltstone, and mudstone. Siltstones exhibit the highest movable fluid saturation (MFS), followed by fine sandstones and mudstones sequentially. Fluid mobility is predominantly governed by the content of brittle minerals, the sorting coefficient (Sc), effective pore connectivity (EPC), and the fractal dimension (D2). High content of brittle minerals favors the preservation of intergranular pores and the generation of microcracks, thus offering more occurrence space for movable fluids. A moderate Sc indicates the presence of larger connecting throats between pores, enhancing fluid mobility. Elevated EPC suggests more interconnected pore throat spaces, facilitating fluid movement. A higher D2 implies a more intricate effective pore structure, increasing the surface area of the rough pores and thereby impeding fluid mobility. Ultimately, this study developed a conceptual model that illustrates fluid distribution patterns across different reservoirs in the Lucaogou Formation, incorporating sedimentary contexts. This model also serves as a theoretical framework for assessing fluid mobility and devising engineering strategies for hydrocarbon exploitation in mixed fine-grained sedimentary rocks.

CO2 capture performance of a 1-dimethylamino-2-propanol/N-(2-hydroxyethyl) ethylenediamine biphasic solvent

Biphasic solvents are widely used for CO2 capture owing to their low regeneration heats; however, they typically suffer from poor regeneration performance and excessive energy consumption. In this study, a mixture of 1-dimethylamino-2-propanol (1DMA2P) and N-(2-hydroxyethyl) ethylenediamine (AEEA) was proposed for CO2 capture. By optimizing the 1DMA2P and AEEA concentrations, this biphasic solvent achieved superior phase separation and excellent absorption and regeneration performance. The proportion of CO2-rich phase was 66.67 %, with a CO2-rich phase loading of up to 5.07 mol/L. The desorption rate was improved by 106.7 % compared to that of conventional 5 mol/L monoethanolamine, and the regeneration efficiency up to 71.8 % in 60 min. Initially, CO2 reacted with AEEA at a faster rate to form a carbamate product. Subsequently, 1DMA2P acted as a proton acceptor, facilitating the formation of bicarbonates and carbonates. Nuclear magnetic resonance analysis indicated that the reaction products (AEEACOO-, AEEAH+, and HCO3–/CO32–) migrated to one phase, whereas 1DMA2P and any unreacted AEEA migrated to the other phase. Additionally, the disparity in polarity between the reactants and reaction products constituted the primary determinant for the phase transition. Notably, the regeneration heat of the 1DMA2P/AEEA biphasic solvent (1.83 GJ/t CO2) was approximately 54.1 % lower than that of conventional 5 mol/L monoethanolamine. Owing to its superior absorption properties, excellent regeneration performance, and low regeneration heat, the 1DMA2P/AEEA biphasic solvent is a promising candidate for practical CO2 capture systems.

Coupling control of organic and inorganic rock components on porosity and pore structure of lacustrine shale with medium maturity: A case study of the Qingshankou Formation in the southern Songliao Basin

Shale components affect organic–inorganic diagenesis, control the formation and evolution of pore structure, and lead to heterogeneity of shale reservoirs. Therefore, revealing the coupling control of shale components on the porosity and pore structure is crucial for selecting the dominant lithofacies. In this study, the lacustrine shale with medium maturity in the first member of the Qingshankou Formation (Qing1 Member) in the Changling Sag, southern Songliao Basin, China, was analyzed. Using pressurized sealed original shale samples and 2-D nuclear magnetic resonance (2D-NMR) analysis, the effective porosity of shale was accurately determined. The pore structure was characterized via experiments such as low-temperature nitrogen adsorption, NMR, and scanning electron microscope (SEM) analyses. In addition, the joint influences of the shale rock components, sedimentary structure, and maturity on the porosity and pore structure were investigated. Finally, the favorable reservoirs in the lacustrine shale with medium maturity and their formation conditions were identified. Studies have shown that for lacustrine shale with medium maturity: (1) a moderate total organic carbon (TOC) content (between 1% and 2.5%) is a key factor for improving the effective porosity and the proportions of mesopores (100–1000 nm) and small-pores (30–100 nm). This is related to the generation of organic acids and the cracking of organic matter into pores. An excessive TOC content can lead to increased plasticity of the rock and filling of the pores by bitumen. (2) The porosity and pore structure are controlled by the organic matter and inorganic minerals as well as sedimentary structure. Organic matter has dual impacts on the porosity improvement related to clay minerals, promotion of clay conversion and filling of clay-related pores, and the ratio of the clay content to the TOC (Vsh/TOC) can reflect the degree of influence of organic matter, the greater the Vsh/TOC ratio is, the greater the effective porosity and proportion of micropores are. (3) Organic matter and felsic minerals jointly effect the improvement of the effective porosity and larger pores (>30 nm), which is related to their good compression resistance, organic pore retention, and dissolution-enhanced porosity effect. The product of the TOC and felsic mineral content (Vsi*TOC) can reflect the degree of their coupled effect. For moderate TOC contents, a higher felsic mineral content, and moderate shell laminae (Vca>10%) are conducive to the development of the effective porosity and larger pores. (4) The organic medium-rich argillaceous laminated felsic shale and organic-medium argillaceous laminated clayey shale have a higher effective porosity and higher proportion of larger pores, making them the dominant lithofacies for shale oil sweet spots.

The influence of carbon dioxide concentration on carbonation behavior in cement paste

Accelerated carbonation is the main method of simulating carbonation in the laboratory, but there are significant differences in the CO2 concentrations adopted for accelerated carbonation testing among the various standards currently. In this work, X-ray imaging technology was used to study the distribution of the carbonation zone in samples at different CO2 concentrations and used for imaging, which was followed by quantitative analyses of the carbonation profile and the material compositions of the entire carbonation zone in combination with thermogravimetric analysis (TGA) and 29Si nuclear magnetic resonance (29Si NMR) analyses. The results showed that the carbonation profiles of cement paste were similar under 3% and 10% concentration, with the front line of carbonation developing parallel to the soffit of the sample. However, when the concentration was increased to 20%, the carbonation profile at partial carbonation zone could be changed due to shrinkage cracking. In addition, the compositions of the complete carbonation zone under different concentrations were similar, and the development of this zone followed Fick's law.

1H Nuclear Magnetic Resonance, Infrared, and Chemometrics in Lipid Analysis of Brazilian Edible-Oil-Based Nutraceuticals

Edible oils have commercial and nutritional value due to the presence of essential fatty acids. They can be consumed fresh in the form of capsules known as nutraceuticals. The quality of such products is of interest to the consumer. In this context, this study describes a method based on high-resolution nuclear magnetic resonance (NMR) and Fourier-transform mid-infrared spectroscopic analysis (FTIR), combined with statistical analyses, to differentiate different edible oils used as nutraceuticals in Brazil by fatty acid content. Through the analysis of 1H NMR spectra, the levels of saturated and unsaturated fatty acids in edible oils were characterized and quantified. Statistical analysis of the data confirmed the real distinctions between nutraceutical raw materials, with emphasis on ω-9, ω-6, and ω-3 fatty acids. The analytical approach presented also demonstrates the potential to identify the origin (animal or vegetable) of edible oils used as nutraceuticals.

Utilizing municipal solid waste incineration bottom ash and volcanic tuff to produce geopolymer materials

Large volumes of municipal solid waste incineration bottom ash (MSWIBA) are produced annually in China; however, their improper disposal causes serious ecological and environmental problems. This study investigated the feasibility of using MSWIBA and volcanic tuff to produce geopolymers. The effects of the MSWIBA content, silicon–sodium molar ratio, and alkali equivalent on the uniaxial compressive strength (UCS) and bulk density of the geopolymer samples were examined using single-factor and optimization tests. The test results showed that the UCS and bulk density of the geopolymer decreased as the MSWIBA content increased, whereas they increased as the alkali equivalent increased. As the silicon–sodium molar ratio increased, the UCS first increased and then decreased, and the change in bulk density was limited. In the final geopolymer preparation, the MSWIBA content was 17.85%, the silicon–sodium molar ratio was 1.71, and the alkali equivalent was 9.49%. According to X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive spectrometry, and nuclear magnetic resonance analyses, the main phases of the geopolymer under the final preparation parameters were quartz, sanidine, calcite, orthoclase, gismondine, and illite. During the geological polymerization process, a large amount of CNASH gel was generated and attached to the surface of the particles or filled the pores between the particles, resulting in a pore size of 0.01–1 μm. The heavy metals in the geopolymers exhibited a good stabilization effect owing to the CNASH gel. Except for Cd, which posed a medium risk, the remaining heavy metals posed low or no risk.

Isolation, anticancer potency, and camptothecin-producing ability of endophytic fungi isolated from Ixora chinensis.

Camptothecin (CPT) is an important alkaloid used for anticancer treatment. It is mainly produced by two endangered and overharvested Camptotheca acuminata and Nothapodytes nimmoniana plants. Endophytic fungi are promising alternative sources for CPT production. In the present study, fungi residing within explants of Ixora chinensis were isolated and their CPT-producing capability of their endophytes was verified via thin-layer chromatography, high-performance liquid chromatography, liquid chromatography/high resolution mass spectrometry, and nuclear magnetic resonance analyses and compared with standards. In addition, MTT and sulforhodamine B assays were selected to test the anticancer effect. The endophytic fungi collection of 62 isolates were assigned to 11 genera, with four common genera (Diaporthe, Phyllosticta, Colletotrichum, and Phomopsis) and seven less common genera (Penicillium, Botryosphaeria, Fusarium, Pestalotiopsis, Aspergillus, and Didymella). Moreover, the anticancer activity of extracts was assessed against human lung carcinoma (A549). Among eight potential extracts, only Penicillium sp. I3R2 was found to be a source of CPT, while the remaining seven extracts have not been discovered potential secondary compounds. Thus, other prominent endophytic fungi might be potential candidates of phytochemicals with anticancer properties.

Preparation, Characterization, and Biological Activity of La(III), Nd(III), Er(III), Gd(III), and Dy(III) Complexes with Schiff Base Resulted from Reaction of 4-Antipyrinecarboxaldehyde and 2-Aminobenzothiazole

The research includes the preparation of several complexes of the internal transition elements lanthanide (Ln = La, Nd, Er, Gd, and Dy) containing the 4f shell, with Schiff bases resulting from condensation reactions between 4-antipyrinecarboxaldehyde and 2-aminobenzothiazoles. Schiff's base was identified using FTIR spectra, UV-vis spectroscopy, elemental microanalysis CHNSO, nuclear magnetic resonance, mass spectrometry, and TGA thermal analysis. The complexes were studied and identified with elemental microanalysis CHNSO, FTIR spectroscopy, UV-vis spectroscopy, TGA thermal analysis, conductivity measurement, and magnetic sensitivity. The result showed that these complexes were classified as homogeneous bidentate complexes with the general formula of [Ln2(L)2(NO3)6]·6H2O. The physical measurements indicated that the prepared complexes are non-electrolyte and paramagnetic. Some compounds prepared in vitro were evaluated for their antibacterial activity against four types of pathogenic strains Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Klebsiella pneumonia, and using the agar disc spreading method for the evaluation. The results showed that some of these complexes have good antibacterial activity compared to the biological activity of the ligand. Also, the biological activity of Schiff's base and the prepared complexes were evaluated against three types of fungi (Candida albicans, Tropical fungi, and Scandal fungi), and they showed great activity against the prepared complexes.

Purification of triterpenoid saponins and 25R/25S-inokosterone from Achyranthes bidentata Bl. by high-speed countercurrent chromatography coupled silver nitrate coordination.

An effective method by high-speed countercurrent chromatography coordinated with silver nitrate for the preparative separation of sterones and triterpenoid saponins from Achyranthes bidentata Blume was developed. Methyl tert-butyl ether/n-butanol/acetonitrile/water (4:2:3:8, v/v/v/v) was selected for 20-hydroxyecdysone (compound 1), chikusetsusaponin IVa methyl ester (compound 4), 2'-glycan-11-keto-pigmented saponin V (compound 5), as well as a pair of isomers of 25S-inokosterone (compound 2) and 25R-inokosterone (compound 3), which were further purified by silver nitrate coordinated high-speed countercurrent chromatography. What is more, dichloromethane/methanol/isopropanol/water (6:6:1:4, v/v/v/v) was applied for calenduloside E (compound 6), 3β-[(O-β-d-glucuronopyranosyl)-oxy]-oleana-11,13-dien-28-oic acid (compound 7), zingibroside R1 (compound 8) and chikusetsusaponin IVa (compound 9). Adding Ag+ to the solvent system resulted in unique selectivity for 25R/25S isomers of inokosterone, which increased the complexing capability and stability of Ag+ coordinated 25S-inokosterone, as well as the α value between them. These results were further confirmed by the computational calculation of geometry optimization and frontier molecular orbitals assay. Comprehensive mass spectrometry and nuclear magnetic resonance analysis demonstrated the structures of the obtained compounds.

Integrated exploration of intermolecular interactions in 3-methyl-1-butanol and C5-C8 1-alkanol mixtures via density functional theory and experimental approaches

The investigation provides a study on the thermophysical properties of 3-methyl-1-butanol with medium-chain alcohols (1-pentanol to 1-octanol) within the temperatures 293.15 K to 333.15 K. Findings indicate positive excess molar volumes that escalate with the lengthening of the carbon chain in the alcohols. Viscosity measurements demonstrate negative deviations from ideality, which are accentuated with longer alkyl chains. The analysis suggests that intermolecular forces between 3-methyl-1-butanol and alcohols are weak. Furthermore, the study uses the Cubic Plus Association (CPA) model to establish a relationship between the densities of the mixtures, demonstrating a close match with data obtained through experimentation. The CPA model deviates by a maximum of 0.53 % and indicates the model's reliability in portraying real-world data. Furthermore, this study entails a density functional theory (DFT) investigation of hydrogen bonding among 3-methyl-1-buthanol + 1-alkanol. The analysis encompasses properties including interaction energies, geometrical parameters, nuclear magnetic resonance (NMR) analyses, atoms in molecules analysis (AIM), natural bond orbital analysis (NBO), and excess volume. Our calculations reveal the strongest hydrogen bonding occurs in mixtures of 3-methyl-1-butanol and 1-pentanol, while the weakest interactions form in mixtures of 3-methyl-1-butanol and 1-octanol. Notably, calculated data on hydrogen bonding between 3-methyl-1-buthanol and 1-alkanols align with experimental findings, underscoring the agreement between computational and empirical approaches.

Altered serum metabolome as an indicator of paraneoplasia or concomitant cancer in patients with rheumatic disease

ObjectivesA timely diagnosis is imperative for curing cancer. However, in patients with rheumatic musculoskeletal diseases (RMDs) or paraneoplastic syndromes, misleading symptoms frequently delay cancer diagnosis. As metabolic remodelling characterises both...