Water Proton Research Articles

Understanding the influence of the arabinoxylan-rich psyllium (Plantago ovata) husk on dough elasticity and bread staling: Interplay between biopolymer and water dynamics

Bread staling is a complex phenomenon in which multiple interconnected mechanisms involving water operate, including the formation of amylopectin crystallites sequestering water, crumb-to-crust moisture migration, and the escalating immobilization of water reducing gluten plasticization. Considering the pivotal role of water-gluten-starch interactions, the integration of the highly-soluble, water-avid, arabinoxylan-rich psyllium husk (PSY) into a wheat dough/bread system was explored, to understand the impact of PSY on the water and biopolymer dynamics that could lead to lower staling. With the addition of PSY, optimal dough development required more water (from 68.0 to 119.5 % in control and 10 % wheat flour replacement with PSY, respectively). LF-NMR showed a parallel increase in the proton population attributed to free water entrapped by the continuous network of biopolymers surrounding granular starch (A23), and its relaxation time (T23). PSY resulted in freshly baked bread with similar specific volume, porosity and starch gelatinization than the control, but with a much higher proportion of intergranular free water (A23). Importantly, PSY did not affect amylopectin retrogradation nor shortened the relaxation time of water protons in exchange with gluten, suggesting that PSY did not withdraw plasticizing water from starch or gluten, respectively. During storage, PSY resulted in a dose-dependent delay of both crumb hardening (correlated to T23, r = −0.76, p < 0.05) and loss of cohesiveness (correlated to T23, r = 0.71, p < 0.05 and A23, r = 0.74, p < 0.05). PSY also resulted in greater crumb resilience, which was related to the self-assembly of PSY molecules and its impact on dough elasticity (with up to two-fold increase in recovery strain).

Ultrashort echo time MRI detects significantly lower collagen but higher pore water in the tibial cortex of female patients with osteopenia and osteoporosis.

Ultrashort echo time (UTE) MRI can quantify the major proton pool densities in cortical bone, including total (TWPD), bound (BWPD), and pore water (PWPD) proton densities, as well as the macromolecular proton density (MMPD), associated with the collagen content, which is calculated using macromolecular fraction (MMF) from UTE magnetization transfer (UTE-MT) modeling. This study aimed to investigate the differences in water and collagen contents in tibial cortical bone, between female osteopenia (OPe) patients, osteoporosis (OPo) patients, and young participants (Young). Being postmenopausal and above 55yr old were the inclusion criteria for OPe and OPo groups. The tibial shaft of 14 OPe (72.5 ± 6.8yr old), 31 OPo (72.0 ± 6.4yr old), and 31 young subjects (28.0 ± 6.1yr old) were scanned using a knee coil on a clinical 3T scanner. Basic UTE, inversion recovery UTE, and UTE-MT sequences were performed. Investigated biomarkers were compared between groups using Kruskal-Wallis test. Spearman's correlation coefficients were calculated between the TH DXA T-score and UTE-MRI results. MMF, BWPD, and MMPD were significantly lower in OPo patients than in the young group, whereas T1, TWPD, and PWPD were significantly higher in OPo patients. The largest OPo/Young average percentage differences were found in MMF (41.9%), PWPD (103.5%), and MMPD (64.0%). PWPD was significantly higher (50.7%), while BWPD was significantly lower (16.4%) in OPe than the Young group on average. MMF was found to be significantly lower (27%) in OPo patients compared with OPe group. T1, MMF, TWPD, PWPD, and MMPD values significantly correlated with the TH DXA T-scores (provided by the patients and only available for OPe and OPo patients). DXA T-score showed the highest correlations with PWPD (R = 0.55) and MMF (R = 0.56) values. TWPD, PWPD, and MMF estimated using the UTE-MRI sequences were recommended to evaluate individuals with OPe and OPo.

Synthesis and Characterization of Enhanced Proton-Conducting Nafion&lt;sup&gt;® &lt;/sup&gt;117- Silica Composite Membranes for Fuel Cell Applications

Nafion®/silica nanocomposite membranes were prepared by impregnation method from Nafion® 117 and sol-gel pre-synthesized n-octadecyl-trimethoxy silane (C18TMS) coated silica nanoparticles. The scanning electron microscope (SEM) of pristine silica particles displayed monodispersed nanospheres with diameters ranging from 150-350 nm; while Brunauer-Emmett-Teller (BET) analysis presented 760 m2/g BET surface area, a micropore-mesopore bimodal distribution of micropore systems with respective pore volume at 14.6 Å and 17.0 Å (2.01 x 10-3 cm3/g.Å), as well as the prolific mesopores centered at 29.5 Å (5.64 x 10-2 cm3/g.Å). Characterization of Nafion® 117 based membranes on SEM, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and x-ray diffraction (XRD), and tensile stress exhibited varying surface morphology with silica loadings, structural interaction between membrane support and the ion exchanger, thermal stabilities (up to 330 °C), crystalline nature, and reasonable mechanical stability of nanocomposite membranes. The maximum water uptake (44.8 %) and proton conductivity of (1.14 x10-2 S/cm) were obtained on low Nafion®/SiO2 (5%) loaded membrane. While both composite membranes displayed the improved reduction in methanol permeability, 2.43x10-07 cm2/s at 80 °C was obtained with high Nafion®/SiO2 (10%) loading. Improved water uptake and proton conductivity substantiate the high ion exchange capacity (IEC) of 1.81 meq.g-1 when compared to IEC of 0.93 meq.g-1 [pristine Nafion®] and 1.46 meq.g-1 [Nafion®/SiO2 (10%)]. The increase in IEC value may be due to the high acid functionalization of additional sulfonic acid groups surrounded by hydrophilic segments of nanosilica, which improves the properties of the membrane. The high proton conductivity coupled with great water retention capabilities indicated that the Nafion®/SiO2 nanocomposite membranes could be utilized as proton exchange membranes for medium temperature methanol fuel cells. Keywords: Fuel cells; nanocomposite membrane; SiO2 nanofillers; methanol permeability; ion exchange capacity

Recent Advances and Challenges in Anion Exchange Membranes Development/Application for Water Electrolysis: A Review.

In recent years, anion exchange membranes (AEMs) have aroused widespread interest in hydrogen production via water electrolysis using renewable energy sources. The two current commercial low-temperature water electrolysis technologies used are alkaline water electrolysis (AWE) and proton exchange membrane (PEM) water electrolysis. The AWE technology exhibited the advantages of high stability and increased cost-effectiveness with low hydrogen production efficiency. In contrast, PEM water electrolysis exhibited high hydrogen efficiency with low stability and cost-effectiveness, respectively. Unfortunately, the major challenges that AEMs, as well as the corresponding ion transportation membranes, including alkaline hydrogen separator and proton exchange membranes, still face are hydrogen production efficiency, long-term stability, and cost-effectiveness under working conditions, which exhibited critical issues that need to be addressed as a top priority. This review comprehensively presented research progress on AEMs in recent years, providing a thorough understanding of academic studies and industrial applications. It focused on analyzing the chemical structure of polymers and the performance of AEMs and established the relationship between the structure and efficiency of the membranes. This review aimed to identify approaches for improving AEM ion conductivity and alkaline stability. Additionally, future research directions for the commercialization of anion exchange membranes were discussed based on the analysis and assessment of the current applications of AEMs in patents.

Expanding Mn2+ loading capacity of BSA via mild non-thermal denaturing and cross-linking as a tool to maximize the relaxivity of water protons

Development of nanoparticles (NPs) serving as contrast enhancing agents in MRI requires a combination of high contrasting effect with the biosafety and hemocompatibility. This work demonstrates that bovine serum albumin (BSA) molecules bound to paramagnetic Mn2+ ions are promising building blocks of such NPs. The desolvation-induced denaturation of BSA bound with Mn2+ ions followed by the glutaraldehyde-facilitated cross-linking provides the uniform in size 102.0 ± 0.7 nm BSA-based nanoparticles (BSA-NPs) loaded with Mn2+ ions, which are manifested in aqueous solutions as negatively charged spheres with high colloid stability. The optimal loading of Mn2+ ions into BSA-NPs provides maximum values of longitudinal and transverse relaxivity at 98.9 and 133.6 mM−1 s−1, respectively, which are among the best known from the literature. The spin trap EPR method indicates that Mn2+ ions bound to BSA-NPs exhibit poor catalytic activity in the Fenton-like reaction. On the contrary, the presence of BSA-NPs has an antioxidant effect by preventing the accumulation of hydroxyl radicals produced by H2O2. The NPs exhibit remarkably low hemolytic activity and hemagglutination can be avoided at concentrations lower than 110 μM. Thus, BSA-NPs bound with Mn2+ ions are promising candidates for combining high contrast effect with biosafety and hemocompatibility.

Insights into dynamic properties of water in lipidic cubic phases by 2D nuclear Overhauser effect (NOE) NMR spectroscopy

Two-dimensional NOE (nuclear Overhauser effect) NMR spectroscopy was employed to investigate the dynamic properties of water within lyotropic bicontinuous lipidic cubic phases (LCPs) formed by monoolein (MO). Experiments observed categorically different effective residence times of water molecules: (i) in proximity to the glycerol moiety of MO, and (ii) adjacent to the hydrophobic chain towards the hydrocarbon tail of MO, as evidenced by the opposite signs of intermolecular NOE cross peaks between protons of water and those of MO in 2D 1H–1H NOESY spectra. Spectroscopic data delineating the different effective residence times of water molecules within both the gyroid (QIIG) and diamond (QIID) phase groups corresponding to hydration levels of 35 and 40 wt%, respectively, are presented. Additionally, an increase in effective residence time of water molecules in proximity to the glycerol moiety of MO in LCPs was observed upon storage at ambient temperature and in the presence of an additive lipid, cholesterol. Atom-specific NOE build-up curves for protons of water and those of MO are also given. The results presented herein provide new insight into the physicochemical properties and behaviour of water in LCPs, and demonstrate an additional avenue for experimental study of water–lipid interactions and hydration dynamics in model membranes and nanomaterials using 2D NOE NMR spectroscopy.

The pKa Values of Water in Water: A Long-Standing, Tiresome, yet Soon Forgotten Issue?

The pKa values of water and the hydrogen ion (proton) in water are 14 and 0, respectively. Yet, many textbooks of general, organic, and, to a lesser extent, inorganic chemistry provide the incorrect values 15.74 and -1.74, respectively. This column briefly introduces the long-standing issue of these two different pairs of values, the consequences it bears when teaching general chemistry, and expresses the hope that it may be solved soon.

Density functional theory to study stopping power of proton in water, lung, bladder, and intestine

Abstract Stopping power, range, and time of proton in water, lung, bladder, and intestinal human tissues are calculated using density functional theory and Beth’s relativistic equation in range of proton energy (0.01–1,000 MeV). The experimental data extracted from SRIM-2013 program were used to proton to the same human tissues applied in the MATLAB-2021 program, and the mean ionization potential of water and the studied tissues is calculated using Gaussian 09W program. A good agreement has been found between our calculations for stopping power, range, and time of protons in the studied human body tissues and SRIM-2013 program calculations.

Efficient Electrocatalytic H2 Production by Immobilized Co(III)‐myoglobin

AbstractThe thermodynamics and kinetics of heterogeneous electron transfer (ET) for Co‐substituted horse myoglobin (Co−Mb) and its derivatives with ammonia and imidazole as heme axial ligands were studied with cyclic voltammetry on a pyrolytic graphite electrode along with their ability to mediate the electro‐catalytic production of H2. All the proteins experience a non‐diffusive electrochemical regime as electrode‐bound species. The adsorbed Co−Mb construct carries out the electro‐catalytic reduction of water protons to H2 with a good efficiency under anaerobic conditions thus yielding a simple and tunable system for H2 production. Replacement of H2O as Co axial ligand by ammonia and imidazole significantly lowers the catalytic currents for H3O+/H2O reduction to H2. The E°’ values of the Co(III)/Co(II) redox couple for all species are mainly determined by the enthalpic contribution. Differences were found in the kinetics of ET for the different protein adducts due to changes in the activation enthalpies. However, all species share the same distance of about 14 Å from the electrode surface to the Co(III)/Co(II) center determined using the Marcus model, consistent with a non‐denaturing adsorption of the protein.

A feasibility study of green hydrogen liquefaction for hydrogen refueling station: Multi-criteria based integrative assessment

Considering an important energy vector, hydrogen (H2) has earned enormous attention due to its cleanliness and potential role in decarbonizing the existing systems, e.g., transportation, industrial sector, and commercial units. This is the reason why developing the H2 economy is one of the most crucial aspects under research and numerous studies forecast that the H2 demand will increase many folds in the near future. However, the production of H2 and its transportation have serious challenges due to the fact of energy and cost intensiveness. In this context, we have made an effort to assess the potential feasibility of producing green H2 and simultaneously integrate it with a liquefaction unit to make it ready for transportation. Moreover, the proposed process is evaluated based on renewable energy resources to estimate the potential solution for future energy goals. The proposed model for liquefied H2 (LH2) production claimed high energy efficiency and the value in terms of specific energy consumption is obtained as 5.418 kWh kg LH2−1 for the capacity of 10 ton per day of LH2. A detailed techno-economic analysis provides levelized cost of LH2 by varying criteria for economic feasibility. Environmental assessment results in the lowest environmental potential during green LH2 production, which reveals that the solid oxide electrolysis system is a potential candidate for green LH2 production. As per multi-criteria decision analysis, results showed that the onshore wind with alkaline water electrolysis and proton exchange membrane water electrolysis have high capabilities to become the potential technology for green LH2 production.

A Facile NMR Method for Pre-MRI Evaluation of Trigger-Responsive T1 Contrast Enhancement.

There is a growing interest in developing paramagnetic nanoparticles as responsive magnetic resonance imaging (MRI) contrast agents, which feature switchable T1 image contrast of water protons upon biochemical cues for better discerning diseases. However, performing an MRI is pragmatically limited by its cost and availability. Hence, a facile, routine method for measuring the T1 contrast is highly desired in early-stage development. This work presents a single-point inversion recovery (IR) nuclear magnetic resonance (NMR) method that can rapidly evaluate T1 contrast change by employing a single, optimized IR pulse sequence that minimizes water signal for "off-state" nanoparticles and allows for sensitively measuring the signal change with "switch-on" T1 contrast. Using peptide-induced liposomal gadopentetic acid (Gd3+-DTPA) release and redox-sensitive manganese oxide (MnO2) nanoparticles as a demonstration of generality, this method successfully evaluates the T1 shortening of water protons caused by liposomal Gd3+-DTPA release and Mn2+ formation from MnO2 reduction. Furthermore, the NMR measurement is highly correlated to T1-weighted MRI scans, suggesting its feasibility to predict the MRI results at the same field strength. This NMR method can be a low-cost, time-saving alternative for pre-MRI evaluation for a diversity of responsive T1 contrast systems.

Incorporation of multilayered double hydroxides/sepiolite augments proton conductivity performance in low sulfonated polyether sulfone octyl sulfonamide

AbstractLow-sulfonation-level polyether sulfone octyl sulfonamide (LSPSO) was blended with a layered double hydroxides (LDHs, Mg2AlCl)/sepiolite nanostructure clay as a filler to create an electrolyte membrane for fuel cell applications. Comprehensive characterization of the composite membranes was conducted, encompassing Fourier-transform infrared spectroscopy, X-ray diffraction, mechanical stability assessment, thermal gravimetric analysis, ion exchange capability, swelling characteristics, water uptake performance, and electrochemical impedance spectroscopy analysis. In comparison to the pristine LSPSO membrane, the presence of LDHs/sepiolite nanoarchitecture material within LSPSO exhibited superior water retention and proton conductivity values, especially at elevated temperatures. The proton conductivity of the composite membranes reached approximately 250 mS/cm, while the unmodified LSPSO membrane only achieved 35 mS/cm at 100 °C. Moreover, LSPSO composite membranes demonstrated enhanced chemical and thermal stability along with higher proton conductivity when compared to pristine LSPSO membranes. These findings highlight the potential of developing tailored LSPSO composite membranes to advance the prospects of commercial applications in proton exchange membrane fuel cells.

Artificial Photosynthesis for Regioselective Reduction of NAD(P)+ to NAD(P)H Using Water as an Electron and Proton Source.

In photosynthesis, four electrons and four protons taken from water in photosystem II (PSII) are used to reduce NAD(P)+ to produce NAD(P)H in photosystem I (PSI), which is the most important reductant to reduce CO2. Despite extensive efforts to mimic photosynthesis, artificial photosynthesis to produce NAD(P)H using water electron and proton sources has yet to be achieved. Herein, we report the photocatalytic reduction of NAD(P)+ to NAD(P)H and its analogues in a molecular model of PSI, which is combined with water oxidation in a molecular model of PSII. Photoirradiation of a toluene/trifluoroethanol (TFE)/borate buffer aqueous solution of hydroquinone derivatives (X-QH2), 9-mesityl-10-methylacridinium ion, cobaloxime, and NAD(P)+ (PSI model) resulted in the quantitative and regioselective formation of NAD(P)H and p-benzoquinone derivatives (X-Q). X-Q was reduced to X-QH2, accompanied by the oxidation of water to dioxygen under the photoirradiation of a toluene/TFE/borate buffer aqueous solution of [(N4Py)FeII]2+ (PSII model). The PSI and PSII models were combined using two glass membranes and two liquid membranes to produce NAD(P)H using water as an electron and proton source with the turnover number (TON) of 54. To the best of our knowledge, this is the first time to achieve the stoichiometry of photosynthesis, photocatalytic reduction of NAD(P)+ by water to produce NAD(P)H and O2.

The Missing Chalcogen Bonding Donor: Strongly Polarized Oxygen of Water.

A biscyclen molecular cabin, synthesized by connecting two cyclen macrocycles with four linkages, entraps a Li+···H2O···Li+ trimer with a water molecule clamped by two Li+ ions. This configuration results in strongly polarized water, characterized by a water proton resonance shift of up to 10.00 ppm. The arrangement facilitates unprecedented O-centered chalcogen bonds between the lone pairs of pyridinyl nitrogen atoms and polarized water oxygen, as confirmed by X-ray crystallography, NMR spectroscopy, and theoretical calculations. Further observation of O-centered chalcogen bonding in a H2O·(LiCl)2 cluster suggests its widespread presence in hydrated salt systems.

Ultrasound attenuation of cortical bone correlates with biomechanical, microstructural, and compositional properties

BackgroundWe investigated the relationship of two commonly used quantitative ultrasound (QUS) parameters, speed of sound (SoS) and attenuation coefficient (α), with water and macromolecular contents of bovine cortical bone strips as measured with ultrashort echo time (UTE) magnetic resonance imaging (MRI).MethodsSoS and α were measured in 36 bovine cortical bone strips utilizing a single-element transducer with nominal 5 MHz center frequency based on the time of flight principles after accommodating for reflection losses. Specimens were then scanned using UTE MRI to measure total, bound, and pore water proton density (TWPD, BWPD, and PWPD) as well as macromolecular proton fraction and macromolecular transverse relaxation time (T2-MM). Specimens were also scanned using microcomputed tomography (μCT) at 9-μm isometric voxel size to measure bone mineral density (BMD), porosity, and pore size. The elastic modulus (E) of each specimen was measured using a 4-point bending test.Resultsα demonstrated significant positive Spearman correlations with E (R = 0.69) and BMD (R = 0.44) while showing significant negative correlations with porosity (R = -0.41), T2-MM (R = -0.47), TWPD (R = -0.68), BWPD (R = -0.67), and PWPD (R = -0.45).ConclusionsThe negative correlation between α and T2-MM is likely indicating the relationship between QUS and collagen matrix organization. The higher correlations of α with BWPD than with PWPD may indicate that water organized in finer structure (bound to matrix) provides lower acoustic impedance than water in larger pores, which is yet to be investigated thoroughly.Relevance statementThis study highlights the importance of future investigations exploring the relationship between QUS measures and all major components of the bone, including the collagenous matrix and water. Investigating the full potential of QUS and its validation facilitates a more affordable and accessible tool for bone health monitoring in clinics.Key points• Ultrasound attenuation demonstrated significant positive correlations with bone mechanics and mineral density.• Ultrasound attenuation demonstrated significant negative correlations with porosity and bone water contents.• This study highlights the importance of future investigations exploring the relationship between QUS measures and all major components of the bone.Graphical

Performance of Anion Exchange Membrane Water Electrolysis with High Ionic Strength Electrolyte

Anion exchange membrane water electrolysis (AEMWE) provides the advantages of conventional alkaline water electrolysis and proton exchange membrane water electrolysis for low-temperature hydrogen production. This study investigates the effect of ionic strength in low hydroxide concentration anolyte on AEMWE performance. The anolyte was recirculated at the anode, and the cathode was operated dry. Different alkali cations in the high ionic strength anolyte improved the cathode overpotential by increasing the water transport from the anode to the cathode. Li+, Na+, K+, and Cs+ cations were tested with K+ providing the lowest electrolysis overpotential among the cations tested. The transference number of the alkali cations was measured by a modified Bruce-Vincent method using a membrane electrode assembly, composed of a hydrogen-evolving cathode and oxygen-evolving anode and anion exchange polymer membrane. The result shows that the cathode overpotential is influenced by the cation mobility, which is related to the hydration shell width. The electrolysis overpotential trend with different alkali cations in the anolyte scaled with the alkali dynamic ionic radius. Durable electrolysis was performed in 1,000 h test at 60 °C and 1 A cm−2.

PH-Controlled Reversible Folding of Copolymers via Formation of β-sheet Secondary Structures.

Protein functions are enabled by their perfectly arranged 3D structure, which is the result of a hierarchical intramolecular folding process. Sequence-defined polypeptide chains form locally ordered secondary structures (i.e., α-helix and β-sheet) through hydrogen bonding between the backbone amides, shaping the overall tertiary structure. To generate similarly complex macromolecular architectures based on synthetic materials, a plethora of strategies have been developed to induce and control the folding of synthetic polymers. However, the degree of complexity of the structure-driving ensemble of interactions demonstrated by natural polymers is unreached, as synthesizing long sequence-defined polymers with functional backbones remains a challenge. Herein, we report the synthesis of hybrid peptide-N,N-Dimethylacrylamide copolymers via radical Ring-Opening Polymerization (rROP) of peptide containing macrocycles. The resulting synthetic polymers contain sequence-defined regions of β-sheet encoding amino acid sequences. Exploiting the pH responsiveness of the embedded sequences, protonation or deprotonation in water induces self-assembly of the peptide strands at an intramacromolecular level, driving polymer chain folding via formation of β-sheet secondary structures. We demonstrate that the folding behavior is sequence dependent and reversible.

PH‐Controlled Reversible Folding of Copolymers via Formation of β‐sheet Secondary Structures

AbstractProtein functions are enabled by their perfectly arranged 3D structure, which is the result of a hierarchical intramolecular folding process. Sequence‐defined polypeptide chains form locally ordered secondary structures (i.e., α‐helix and β‐sheet) through hydrogen bonding between the backbone amides, shaping the overall tertiary structure. To generate similarly complex macromolecular architectures based on synthetic materials, a plethora of strategies have been developed to induce and control the folding of synthetic polymers. However, the degree of complexity of the structure‐driving ensemble of interactions demonstrated by natural polymers is unreached, as synthesizing long sequence‐defined polymers with functional backbones remains a challenge. Herein, we report the synthesis of hybrid peptide‐N,N‐Dimethylacrylamide copolymers via radical Ring‐Opening Polymerization (rROP) of peptide containing macrocycles. The resulting synthetic polymers contain sequence‐defined regions of β‐sheet encoding amino acid sequences. Exploiting the pH responsiveness of the embedded sequences, protonation or deprotonation in water induces self‐assembly of the peptide strands at an intramacromolecular level, driving polymer chain folding via formation of β‐sheet secondary structures. We demonstrate that the folding behavior is sequence dependent and reversible.

Quantum dipole interactions and transient hydrogen bond orientation order in cells, cellular membranes and myelin sheath: Implications for MRI signal relaxation, anisotropy, and T1 magnetic field dependence.

Despite significant impact on the study of human brain, MRI lacks a theory of signal formation that integrates quantum interactions involving proton dipoles (a primary MRI signal source) with brain intricate cellular environment. The purpose of the present study is developing such a theory. We introduce the Transient Hydrogen Bond (THB) model, where THB-mediated quantum dipole interactions between water and protons of hydrophilic heads of amphipathic biomolecules forming cells, cellular membranes and myelin sheath serve as a major source of MR signal relaxation. The THB theory predicts the existence of a hydrogen-bond-driven structural order of dipole-dipole connections within THBs as a primary factor for the anisotropy observed in MRI signal relaxation. We have also demonstrated that the conventional Lorentzian spectral density function decreases too fast at high frequencies to adequately capture the field dependence of brain MRI signal relaxation. To bridge this gap, we introduced a stretched spectral density function that surpasses the limitations of Lorentzian dispersion. In human brain, our findings reveal that at any time point only about 4% to 7% of water protons are engaged in quantum encounters within THBs. These ultra-short (2 to 3 ns), but frequent quantum spin exchanges lead to gradual recovery of magnetization toward thermodynamic equilibrium, that is, relaxation of MRI signal. By incorporating quantum proton interactions involved in brain imaging, the THB approach introduces new insights on the complex relationship between brain tissue cellular structure and MRI measurements, thus offering a promising new tool for better understanding of brain microstructure in health and disease.

Amide Proton Transfer-Weighted Magnetic Resonance Imaging for Application in Renal Fibrosis: A Radiological-Pathological-Based Analysis

Plain Language SummaryAmide proton transfer (APT) MRI, a novel molecular MRI technique, could indirectly measure the peptide or protein concentration within tissues based on frequent exchange between amide proton and the surrounding water protons. This new technology has been used in tumor diagnosis. Given pathological conditions linked to tissue fibrogenesis are similar to carcinogenesis, we proposed the hypothesis that APT MRI can be applied to assess collagen deposition in RF. To test this, we constructed animal models for RF and enrolled CKD patients, respectively. The results suggested APT values were more sensitive to the early stage of fibrosis than ADC values, and the cortical APT was highly positively correlated with the degree of fibrosis. We further identified that the combination of two MRI protocols, cortical apparent diffusion coefficient and cortical APT, was an excellent indicator for the diagnosis of fibrosis, with much higher accuracy than a single method. To the best of our knowledge, this is the first study to explore the value of APT imaging for assessing renal interstitial fibrosis. Our findings identify APT as a novel and precise imaging diagnostic tool for future noninvasive assessment of RF. It complements with the existing imaging biomarkers and adds value to conventional MRI.