Inactive Sites Research Articles

Capability of isoprene and butadiene as comonomers under metallocene catalysis: Activating active sites with the addition of 1-hexene and propylene

The copolymerization of ethylene (E) with cyclic diene has been reported often in the literature. However, to evaluate isoprene (IP) and butadiene (BD) as co- and ter-monomers catalyzed by metallocene are comparatively rare. In this work, we performed a set of co- and terpolymerization of IP and BD by using symmetrical metallocene catalysts Cat-I and Cat-II. The E/IP and E/BD copolymers Cat-I catalyzed activity is lower than PE and E/P and significantly increased, reaching 3.1 × 107gpolymer/molCat*h, but unlikely the insertion of IP and BD were not detected. The active sites of Cat-I are not factional for IP and BD, and they are not even activated with the addition of 1-hexene (1H) and P. The 1,4-insertion of these into catalyst active sites produced a stable π-allyl type species that actively produced dormant sites in the consequent propagation chain, and many other reactions that convert to dormant sites occur. In contrast, the Cat-II bearing silicon bridged moiety shows additional activity with IP and BD and an increasing trend with P and IH, demonstrating an activating feature. To conduct an extensive investigation, we performed a systematic comparison of the proportion of catalytically [Zr]/[C*] active sites and polymerization rate constant (kp) for both catalysts to shed light on the Zn-based chain termination and transfer reactions. The [C*]/[Zr] was significantly decreased with IP and BD, but compared to BD, IP shows a higher level of active sites and molecular weight, demonstrating that chain transfer reactions are faster with BD. Adding P and 1H increased the [C*]/[Zr], reactivating the prior inactive sites of the catalyst that were dormant or not functioning during the PE, E/IP, and E/BD polymers and reducing the chain transfer reactions. Compared to Cat-I, Cat-II demonstrates a higher level of [C*]/[Zr]; furthermore, the addition of 1H, a slight change in the [C*]/[Zr], while P with IP overall higher level (92.92 %) of the [C*]/[Zr] showed that P with IP shows a double activation for Cat-II and activates all those active sites that were dormant. BD significantly reduced the level of active sites to 49 % compared to IP and showed poisoning for the active site that was active for ethylene. The kpE of E/BD and E/IP polymers are lower than the kpE of E/BD/1H, E/P/IP, E/BD/1H, and E/IP/P, indicating P and 1H significantly activated the dormant sites of the E, IP, and BD that were dormant during the copolymerization. Cat-I catalyzed E/IP/1Hpolymers, the kp1H of 1H is 15.8 L/mol·s, and the kpP of P is 83.3 L/mol·s, demonstrating that the P and more involved in the activation of active sites, and kpP of P is more increased with Cat-II, indicating that substituents of the Cat-II make the catalyst more active for P.

Lattice Boltzmann Model Investigation of Simultaneous Imbibition/Evaporation in PEMFC Cathodic Catalyst Layer Using Reconstructed 3D Image Data from Transmission Electron Microscopy

Proton Exchange Membrane Fuel Cells (PEMFCs) are widely used and significant attention is directed towards optimizing of the cathode catalyst layer. The critical focus revolves around refining the multi-phase boundary of the electrically conducting carbon support, the ion-conducting ionomer, the catalyst particles as well as the pore space that can be either occupied by oxygen (feedstock) or water (product). Challenges related to mass transport limitations of oxygen towards these multiple-phase boundaries, also denoted as active sites, persist, especially when liquid water increasingly saturates the pore space (Fig. 1). Furthermore, the evaporated water additionally hinders oxygen transport in the gas phase1,2. This study focuses on the investigation of pore-scale transport mechanisms inside of the cathodic catalyst layer, taking into account the counter-current diffusion of oxygen and water vapor in the gas phase as well as the generation of liquid water that increasingly saturates the void space. For this purpose, a multi-phase and multi-component pore scale Lattice Boltzmann model (LBM), coupled to two-phase reaction, was implemented. The LBM is tailored based on previous works3,4, including the localized generation of water at constant current densities, the imbibition of the pore structure with water counter-currently to the diffusion of oxygen, and the simultaneous evaporation of water. An actual 3D cathode catalyst layer from a commercial membrane electrode assembly, reconstructed from transmission electron microscopy (TEM) image data, was employed. It was imaged using a source voltage of 200kV and a current of 2 nA. The scanned sample had an approximate total volume of 500 × 500 × 100 nm3. From this, a 3D domain of 138 × 138 × 58 nm3 was reconstructed for this study. A 2D cross-section of the reconstructed image is exemplarily shown in Fig. 1. The in-silico study of water and oxygen transport through the catalyst layer elaborates the relationship between the rates of water invasion and evaporation in dependence of current density and catalyst layer structure. The critical conditions for water flooding are evaluated for different process conditions. Fig. 1 Schematic representation of the cathode catalyst layer: The ionomer is represented in white; the carbon for electron connectivity is represented in gray; pore space for oxygen and water transport in yellow; the black circles represent the active sites, i.e., Pt-particles located at the multi-phase boundary of ionomer, carbon and oxygen-filled pores; the red circles represent the inactive sites, that have no connection to ion and/or oxygen transport pathways. References A. Suzuki et al., Int. J. Hydrogen Energy, 36, 2221–2229 (2011) https://www.sciencedirect.com/science/article/pii/S0360319910022913.M. El Hannach, M. Prat, and J. Pauchet, Int. J. Hydrogen Energy, 37, 18996–19006 (2012) https://www.sciencedirect.com/science/article/pii/S0360319912022069.S. Bhaskaran et al., Dry. Technol., 40, 735–747 (2022) https://doi.org/10.1080/07373937.2021.1898417.S. Bhaskaran et al., Int. J. Hydrogen Energy, 47, 31551–31565 (2022) https://www.sciencedirect.com/science/article/pii/S0360319922030932. Figure 1

Dynamics of direct hydrocarbon PEM fuel cells

Hydrocarbon fuels contain approximately 50 times more energy per unit mass than commercial batteries, thus converting even 10% of the energy contained in hydrocarbon fuels to electrical energy could present a more mass-efficient electrical energy source than batteries. Considering the storability of hydrocarbon fuels compared to hydrogen, the viability of direct hydrocarbon polymer electrolyte membrane fuel cells was examined. With extremely pure (> 99.99%) propane, the cell Open-Circuit Voltage (OCV) was only 0.05 V and produced negligible power. However, with addition of trace quantities of unsaturated hydrocarbons, the cell had an OCV of 0.85 V and produced power, even after the unsaturated hydrocarbon addition was discontinued. At sufficiently high current densities, power output gradually decreased then the cell rapidly “extinguished” but by periodically shutting off the current for short time intervals the average power density could be increased significantly. Chemical analysis revealed that no significant amounts of hydrocarbon intermediates or CO were present in the effluent and that conversion of the hydrocarbon fuel to CO2 and H2O was nearly complete. An analytical model incorporating the relative rates of conversion of active anode catalyst sites to inactive sites and vice versa was developed to interpret this behavior. The model predictions were consistent with the experimental observations; possible physical mechanisms are discussed.

Single active Au1O5 clusters for metabolism-inspired sepsis management through immune regulation

Artificial enzymes with reprogrammed and augmented catalytic activities hold significant potential in biomedicine. However, common issues with biocatalysts are the presence of numerous inactive site atoms, leading to inefficiencies in their catalytic processes. To leverage the full potential of active catalytic sites, we aim to minimize the biocatalyst structure, transitioning from nanoparticles or polymetallic atomic clusters down to singular-active-unit molecules. In this context, we have developed a unique single active-site cluster molecule, Au1-O5-Na9-(OH)4 (AuO) clusters, comprising a single gold atom, five oxygen atoms, and a protective layer, where Au-O acts as a singular-active site displaying elevated catalytic activities without inefficiencies associated with biocatalytic reactions. AuO clusters demonstrate activities reminiscent of nicotinamide adenine dinucleotide oxidase (NOX), glutathione peroxidase (GPx), and urease, among other oxidoreductase functions, through optimal utilization of atoms. Clusters are instrumental in enhancing the redox balance, mitigating inflammation, and averting inflammation-induced cellular apoptosis, thereby preserving immune balance in sepsis. These mechanisms are crucial in sepsis pathogenesis. Demonstrating GPx-like and NOX-like capabilities, the AuO clusters have shown remarkable effectiveness against lipopolysaccharide-induced and cecum ligation puncture-induced multiorgan damage, underscoring their substantial promise for sepsis management.

Research on the Identification of Inactive Mining Sites with the Potential for Soil Contamination in the Jiu Valley – Case Study Balomir Tailings Dump

Abstract Jiu Valley is in an extensive transition process from an area rich in coal deposits to an area with 0 Carbon emissions. Coal mining was carried out in 14 mining perimeters arranged along the Jiu Valley. At the same time, the extraction of the useful mineral substance resulted in waste material that was stored in tailings dumps. Out of the total of 49 landfills, 25 have been greened, 15 are inactive and 9 are active. The total area occupied by them is approximately 210 ha, arranged near mining operations, in the valleys of some streams and even in the vicinity of human settlements. The paper aims to identify the potential for soil contamination due to inactive tailings dumps.

Int&in: A machine learning-based web server for active split site identification in inteins.

Inteins are proteins that excise themselves out of host proteins and ligate the flanking polypeptides in an auto-catalytic process called protein splicing. In nature, inteins are either contiguous or split. In the case of split inteins, the two fragments must first form a complex for the splicing to occur. Contiguous inteins have previously been artificially split in two fragments because split inteins allow for distinct applications than contiguous ones. Even naturally split inteins have been split at unnatural split sites to obtain fragments with reduced affinity for one another, which are useful to create conditional inteins or to study protein-protein interactions. So far, split sites in inteins have been heuristically identified. We developed Int&in, a web server freely available for academic research (https://intein.biologie.uni-freiburg.de) that runs a machine learning model using logistic regression to predict active and inactive split sites in inteins with high accuracy. The model was trained on a dataset of 126 split sites generated using the gp41-1, Npu DnaE and CL inteins and validated using 97 split sites extracted from the literature. Despite the limited data size, the model, which uses various protein structural features, as well as sequence conservation information, achieves an accuracy of 0.79 and 0.78 for the training and testing sets, respectively. We envision Int&in will facilitate the engineering of novel split inteins for applications in synthetic and cell biology.

Multicriteria screening evaluation of geothermal resources on mine lands for direct use heating

Direct use of geothermal energy is the oldest and most versatile form of utilizing geothermal energy. In the last decade, this utilization has significantly increased, especially with the installation of geothermal (ground-source) heat pumps. Many current and inactive mine land sites across the U.S. could be redeveloped with clean energy technologies such as direct use geothermal, which would revitalize former mining communities, help with reducing greenhouse gas emissions, and accelerate the transition to a clean energy economy. We present a multicriteria screening framework to evaluate various aspects of direct-use geothermal projects on mine lands. The criteria are divided into three categories: (1) technical potential, (2) demand and benefits, and (3) regulatory and permitting. We demonstrate the framework using publicly available data on a national scale (continental U.S.). Then, using an example of abandoned coal mines in Illinois and focusing on resource potential, we illustrate how this evaluation can be applied at the state or more local scales when a region’s characteristics drive spatial variability estimates. The strength of this approach is the ability to combine seemingly disparate parameters and inputs from numerous sources. The framework is very flexible—additional criteria can be easily incorporated and weights modified if input data support them. Vice versa, the framework can also help identify additional data needed for evaluating those criteria. The multicriteria screening evaluation methodology provides a framework for identifying potential candidates for detailed site evaluation and characterization.

Suppression of inactive sites in NiMo@amorphous alumina catalysts for hydrodesulfurization reaction: Effect of Ga doping

Hydrodesulfurization (HDS) reaction activity depends on the formation of active NiMoS (completely sulfided multilayer type 2 sites) and inactive NiAl2O4/NixSy phases on the catalyst surface. These inactive phases not only itself inactive for the reaction but also hinder the formation of active NiMoS phases. In addition, the formation of strong Mo-O-Al bonds also lowers the reducibility of the catalyst, suggesting lesser catalytic activity (type 1 sites, partially sulfided single-layer sites). To this end, we report the formation of NiMo/Ga doped amorphous alumina (A-Al2O3) catalysts prepared by the colloidal synthesis method. A-Al2O3 was chosen as a support because it has lower surface energy, better physicochemical properties, and enhanced acidic sites than the crystalline alumina phase, which favours the formation of type 2 sites or weak metal-support interaction (completely sulfided multilayer NiMoS sites). Further, the Ga doping in A-Al2O3 support substitute the tetrahedral Al sites and form GaAl2O4 phases by reducing NiAl2O4 inactive sites, and the free Ni decorate the edges of MoS2 to form HDS active NiMoS sites. Therefore, NiMo/Ga doped A-Al2O3 catalyst (at 1 wt% Ga loading) reported enhanced HDS catalytic activity (25%), HDS reaction rate constant (kHDS-2.15 times) and turn over frequency (TOF-1.3 times) than the conventional NiMo/γ-Al2O3 catalysts.

Preparation, identification, and molecular docking of novel angiotensin-converting enzyme inhibitory peptides derived from rice-based distillers' spent cakes.

Rice-based distillers' spent cake (RDSC), a by-product of the Chinese liquor (Baijiu) industry, is a potential source of angiotensin-converting enzyme (ACE) inhibitory peptide. Since ACE plays a crucial role in controlling hypertension, inhibition of ACE has been widely emphasized. The ACE inhibitory active peptide derived from by-products of food has been recognized as a safer and cheaper inhibitor. Aimed to discover ACE-inhibiting active peptides in RDSC. Hydrolysis of RDSC by alcalase for 4 h followed by ultrafiltration yielded low-molecular-weight (< 3 kDa) fractions. Subsequently, a comprehensive method using a combination of liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) and LC-Q-Exactive-MS to identify the novel short peptides (3-5 amino acids residues; n = 7) and medium-sized peptides (more than 6 amino acids residues; n = 6). In vitro activity assay showed that the peptides KPFFPGL, GFPRPLL, GPPGVF, and VGK exhibited the highest activity with inhibitory concentration of 50% (IC50) of 11.63, 12.34, 19.55, and 33.54 μmol L-1. Molecular docking reveal that the active and inactive sites (Glu123, Asp121, Arg522, and Lys118) play important roles in enhancing the ACE inhibitory activity of peptides. Here we report a comprehensive method that effectively extracted and identified the bioactive peptides from RDSC. Four highly active novel peptides may be the most promising candidates for functional foods against hypertension, provide significant information for enhancing value of rice-based distilled by-products. © 2024 Society of Chemical Industry.

Performance Study of Sustainable Concrete Containing Recycled Aggregates from Non-Selected Construction and Demolition Waste

In the present study, we investigated the mechanical performance of concrete composed of non-selected construction and demolition waste (C&amp;DW) sourced from both old and new sections of an inactive waste landfill site in Karaj, Iran. Initially, we determined the composition of the coarse and fine C&amp;DW used in concrete production. Subsequently, we meticulously examined the physical and chemical properties of both the C&amp;DW and virgin materials to enable thorough comparisons of the results. We then conducted experimental analyses on 33 concrete mixtures containing recycled C&amp;DW, utilizing various tests, including a compressive strength test (CST) for cylindrical and cubic samples, modulus of elasticity (MOE), wide wheel abrasion test (Capon test), British pendulum number (BPN), and ultrasonic pulse velocity (UPV) test. We considered both non-separated fine and coarse C&amp;DW at different replacement ratios in the recycled concrete (RC). Our findings indicate that using non-separated coarse and fine C&amp;DW in concrete yielded satisfactory results, leading to significant savings in virgin materials required for concrete preparation and promoting sustainable development. Furthermore, non-selected C&amp;DW proved to be a viable sustainable material for similar concrete applications. The results revealed a decrease in brick material consumption in various constructions over the past 20 years in Karaj, contributing to the enhanced strength of C&amp;DW concrete. However, the presence of clay minerals in aged landfill sites can adversely affect concrete performance as a potential destructive factor. Despite the possible negative impact of incorporating fine recycled C&amp;DW materials on concrete mechanical performance, the Capon test results demonstrated that the presence of coarse C&amp;DW can enhance concrete’s wear resistance.

Recommendations for improving rigor and reproducibility in site specific characterization

Heterogeneous catalysis is driven by the interaction of reactant molecules and the catalyst surface. The locus of this interaction as well as the surrounding ensemble of atoms is referred to as the catalyst active site. Active site characterization attempts to distinguish active catalytic sites from inactive surface sites, to elucidate the structural and chemical nature of active sites, and to quantify active site concentration. Numerous techniques have been demonstrated to provide compositional and structural information about the active sites within a catalyst. However, each technique has its own limitations and experimental pitfalls that can lead to data misinterpretation or irreproducible results. This work aims to provide an overview of the types of data that can be collected, to outline common experimental challenges and how to avoid them, and to assemble relevant references for the most used active site characterization techniques. More broadly, we aim to outline best practices for researchers to collect, interpret, and report active site characterization data in a way that provides the most benefit to the broader catalysis community. Increasing the rigor and reproducibility of active site characterization offers a strategy to better link properties with catalytic performance and to enable the community to develop consensus concerning these relationships.

P/s-orbital hybridization induced by Mg-doping to active Na sites in Na2FePO4F cathode for long-life and high-rate sodium-ion batteries

The iron-based fluorophosphate Na2FePO4F (NFPF) is considered as a potential cathode for sodium-ion batteries due to the low-cost, non-toxicity and appropriate working voltage. However, the inferior intrinsic electronic conductivity and the restrained active Na sites bring the limits for full realization of electrochemical properties. Herein, Mg2+ with d0 orbital was introduced in FeO4F2 structure, aimed at activating the Na+ at Na1 site and enhancing the electronic conductivity. Different from the 3d transition metal (TM) elements that form 3d-O2p orbital interactions in the FeO4F2 structure, the Mg with d° contributes p and s orbitals mainly in Mg-O bonds, which corresponds to more stable orbital interaction and lattice structure. The electron distribution of bridge O due to the Mg-doping leads to the wooden barrel effect near the Mg site, thus activating Na+ at Na1 site by lowering the energy barrier of Na+ migration from Na1 to Na2 site. Hence, the obtained NFMPF electrode delivers high specific capacity (121.4 vs. 108.7 mAh g−1 at 0.1 C) and better cycling stability (73.8% vs. 54.2 % after 1000 cycles at 20 C). Overall, regulating the electronic structure and activating Na+ at inactive site is the key to break the bottleneck of low activity, which can be an effective strategy to design cathode materials with excellent electrochemical performance.

Photoelectron Holographic Study for Atomic Site Occupancy for Si Dopants in Si-Doped κ-Ga2O3(001).

We investigated atomic site occupancy for the Si dopant in Si-doped κ-Ga2O3(001) using photoelectron spectroscopy (PES) and photoelectron holography (PEH). From PES and PEH, we found that the Si dopant had one chemical state, and three types of inequivalent Si substitutional sites (SiGa) were formed. The ratios for the inequivalent tetrahedral, pentahedral, and octahedral SiGa sites were estimated to be 55.0%, 28.1%, and 16.9%, respectively. Higher (lower) ratios for the three inequivalent SiGa sites may come from a lower (higher) formation energy. The Tetra (Octa) SiGa site has the highest (lowest) ratio of the three SiGa sites since it has the lowest (highest) formation energy. We suggest that the tetrahedral SiGa site is due to the active dopant site, whereas the pentahedral and octahedral SiGa sites can be attributed to the inactive dopant sites for Si-doped κ-Ga2O3(001).

Homeostatic Solid Solution Reaction in Phosphate Cathode: Breaking High-Voltage Barrier to Achieve High Energy Density and Long Life of Sodium-Ion Batteries.

The stable phase transformation during electrochemical progress drives extensive research on vanadium-based polyanions in sodium-ion batteries (SIBs), especially Na3 V2 (PO4 )3 (NVP). And the electron transfer between V3+/4+ redox couple in NVP could be generally achieved, owing to the confined crystal variation during battery service. However, the more favorable V4+/5+ redox couple is still in hard-to-access situation due to the high barrier and further brings about the corresponding inefficiency in energy densities. In this work, the multilevel redox in NVP frame (MLNP) alters reaction pathway to undergo homeostatic solid solution process and breaks the high barrier of V4+/5+ at high voltage, taking by progressive transition metal (V, Fe, Ti, and Cr) redox couple. The diversified reaction paths across diffusion barriers could be realized by distinctive release/uptake of inactive Na1 site, confirmed by the calculations of density functional theory. Thereby its volume change is merely 1.73% during the multielectron-transfer process (≈2.77 electrons). MLNP cathode could achieve an impressive energy density of 440Wh kg-1 , driving the leading development of MLNP among other NASICON structure SIBs. The integration of multiple redox couples with low strain modulates the reaction pathway effectively and will open a new avenue for fabricating high-performance cathodes in SIBs.

Emergence of electrochemical catalytic activity via an electrochemical-probe on defective transition metal dichalcogenide nanosheets

Two-dimensional transition metal dichalcogenides (2D TMDs) have shown exceptional electrochemical catalytic activity for the efficient generation of hydrogen through electrochemical water splitting. In the case of molybdenum disulfide (MoS2), a prominent member of 2D TMDs, the electrochemically active sites primarily reside at the edges, while the basal plane, which constitutes the majority of the MoS2 structure, remains relatively inactive. In this study, we aimed to activate the inert sites of the basal plane with some defective structure for hydrogen evolution reaction (HER) by employing an electrochemical-probe in combination with voltage sweeping. The initiation of HER at these previously inactive sites was visualized and confirmed using scanning electrochemical cell microscopy (SECCM). Our findings reveal that the enhanced HER activity originates from surface defects induced by the probing process.

Exploring the influence of interfacial solvation on electrochemical CO2 reduction using plasmon‐enhanced vibrational sum frequency generation spectroscopy

AbstractAlthough interfacial solvation plays an important role in determining carbon dioxide reduction (CO2R) kinetics, present understanding of the potential dependent properties of the electrochemical double layer under conditions relevant for CO2R remains limited. This article summarizes the development and recent applications of plasmon‐enhanced vibrational sum frequency generation (VSFG) spectroscopy to study the effects of cation hydration and interfacial solvation on CO2R using CO as a vibrational Stark reporter. Results show that electrolyte cations retain their entire solvation shell upon adsorption to inactive sites, while active sites retain only a single water layer between the gold surface and the cation. Measurements also show that the total interfacial electric field can be separated into two contributions: one from the electrochemical double layer (Stern field) and another from the polar solvation environment (Onsager field). Surprisingly, correlating VSFG spectra with reaction kinetics reveals that it is the solvation‐mediated Onsager field that governs the chemical reactivity at the electrode/electrolyte interface. Measuring the interfacial water spectra during electrocatalysis also provides evidence for the proton source during H2 evolution, which competes with CO2R in aqueous electrolyte. These findings highlight the importance of directly probing cation hydration and interfacial solvation, which mediates reaction kinetics at electrochemical interfaces.

Dianthus sylvestris subsp. sylvestris as a promising candidate for phytostabilization of copper-contaminated post-mining sites in Alpine ecosystems.

The lack of remediation of inactive mine sites is a serious global concern, as they pose risks to the environment, human health, and safety. The potential of Dianthus sylvestris subsp. sylvestris to remediate post-mining sites contaminated with copper (Cu) at high altitudes, which is a challenging task for most management strategies, was explored in this study. More than 1300 mg Cu kg-1 in shoots were found in plants collected at the Monte Avanza legacy mine site (Alps). However, it is unclear whether this is due to hyperaccumulation or foliar contamination. To address this gap, field samples were washed with two different protocols, and a controlled Cu-tolerance test was conducted. While very high Cu concentrations, exceeding the Cu hyperaccumulation threshold of 300 mg kg-1, were found in samples washed with water, results for the plants cleaned with a more rigorous approach with EDTA suggested Cu exclusion strategy. Under controlled conditions, the plant showed Cu hypertolerance but did not hyperaccumulate Cu. Thus D. sylvestris presents a Cu exclusion strategy rather than hyperaccumulation potential, making it a suitable candidate for Cu phytostabilization at high altitude legacy mine sites. The study emphasizes the need for experiments under controlled conditions when assessing the phytoremediation potential.

Upfront Radiation Therapy (RT) for Post-Stem Cell Transplant Multiple Myeloma (MM) Patients with Oligo-Relapse/Progressive Disease: Factors Associated with Favorable Outcomes

Introduction: Relapsed or refractory disease post-stem cell transplant (SCT) for Multiple Myeloma (MM) can be clinically challenging. For localized relapses, radiation therapy (RT) can represent an attractive treatment modality. However, data on outcomes with RT remains scarce. We investigated the impact of RT as a treatment modality in the setting of oligo-relapse and oligo-progressive plasmacytomas after SCT and explored prognostic factors associated with favorable long-term outcome Methods: In this single-institution retrospective analysis, we identified 31 MM patients who underwent upfront RT for oligo-relapse or oligo-progressive MM after SCT between 2000 and 2021. Patients were excluded if they had received systemic therapy for evidence of concurrent biochemical relapse prior to RT start. The treatment responses to stem cell transplantation (SCT) and RT were assessed following the response criteria established by the International Myeloma Working Group (IMWG), which includes the categories: complete response (CR), very good partial response (VGPR), partial response (PR), minimal response (MR), stable disease (SD) and progressive disease (PD). Additionally, we utilized the R-ISS staging system to classify patients into Standard-Risk (R-ISS I), Intermediate-Risk (R-ISS II), and High-Risk (R-ISS III) groups, to allow for a comprehensive evaluation of treatment efficacy and outcomes. Results: Disease and treatment characteristics for the cohort are summarized inFigure 1. Of the 27 patients with imaging available prior to SCT, 67% (18) were assessed with PET, 22% (6) with skeletal survey, 3.7% (1) with MRI/CT, 3.7% with CT, and 3.7% (1) with x-ray. Following SCT, 48% (13) of patients were noted to have radiographic progression, 23% (7) had sCR, 23% (7) had a CR, 10% had a serologic CR, and 45% (14) had a VGPR. Among the 18 patients with radiographic evaluation (in addition to bone marrow biopsy and/or labs) post-SCT, 67% (12) were in radiographic CR at time of re-staging. Median times from SCT to new site of oligo-relapsed disease (20, 64.5%) and pre-existing but inactive sites of oligo-relapsed MM (4, 12.9%) were 31 months (3.2-117.5) and 9 months (3.4-15.9), respectively. Oligo-progressive MM, defined as active sites of disease both pre- and post-SCT were present in 22.6% (7) of patients. Prior to RT, 94% (29) had PET/CT imaging, with a median SUV of 4.4 (2.6-7.2) for target lesions. Solitary bone (77%) and extramedullary (23%) disease were treated to median dose of 30 Gy (8-49 Gy). At first disease response assessment post-RT, 77% (24) of which was done with PET/CT imaging , 42% (13) achieved CR. Among the 18 patients that did not achieve CR, 15 subsequently achieved CR at a median time of 7 months (1.7-44.5). A majority of patients (87%) received systemic therapy post-RT, with a median number of lines of therapy post-RT of 3 (1-17). The remaining 13% (4) of patients did not receive additional systemic therapy post-RT and did not experience progression. Median overall survival for the full cohort was 38 months (3.5-37.9). Conclusions: Utilizing modern systemic therapies in combination with post-transplant RT for patients with limited refractory or relapsed MM is a promising therapeutic approach. For those that remain refractory or relapse in a single site RT local control merits consideration supported by our report. Further investigation to identify patients at highest risk of progression and who may therefore benefit most from RT would be valuable. We plan to conduct additional analyses on the radiographic characteristics that may portend high risk disease, with the ultimate goal of developing well-defined criteria for giving RT earlier.

The inhibition mechanism of bound polyphenols extracted from mung bean coat dietary fiber on porcine pancreatic α-amylase: kinetic, spectroscopic, differential scanning calorimetric and molecular docking

The inhibitory mechanisms of purified bound polyphenols extracted from mung bean coat dietary fiber (pMBDF-BP) on porcine pancreatic α-amylase (PPA) were investigated through inhibition kinetics, fluorescence spectroscopy, circular dichroism, differential scanning calorimetry and molecular docking. It was shown that pMBDF-BP exerted significant reversible inhibition on PPA in a mixed-type inhibition manner (IC50 = 18.57 ± 0.30 μg/mL), and the combination of the three major components exhibited a synergistic inhibitory effect on PPA. Further, pMBDF-BP bound to the active site or form a polyphenol-enzyme complex at the inactive site through hydrogen bonding and hydrophobic forces, via enhancing the hydrophobicity of the microenvironment surrounding tryptophan and tyrosine residues and promoting the secondary structure of PPA towards a more stable conformation, eventually reducing the enzyme activity. This study provided theoretical evidences for the utilization of bound polyphenols extracted from mung bean coat dietary fiber as a functional component in natural inhibitors of α-amylase.

Atomic Structures and Chemical states of active and inactive dopants in GaN

We investigated atomic structures and chemical states of active and inactive dopant sites for Mg- and Si- doped in GaN using photoelectron holography and X-ray absorption near edge structure. In the case of Mg-doped GaN, we found that a Mg atom substituting a Ga atom (MgGa) is an active dopant site in GaN whereas MgGa with two H atoms is an inactive dopant site in GaN. We found that a Si atom substituting a Ga atom is an active dopant site in Si-doped GaN whereas Si3N4 is an inactive dopant site in GaN.