Exploring the effect of molecular size and framework functionalisation on transport in metal-organic frameworks using pulsed-field gradient nuclear magnetic resonance.

Molecular transport is an important aspect in metal-organic frameworks (MOFs) as it affects many of their applications, such as adsorption/separation, drug delivery and catalysis. Yet probing the fundamental diffusion mechanisms in MOFs is challenging, and the interplay between the MOF's features (such as the pore structure and linker dynamics) and molecular transport remains mostly unexplored. Here, the pulsed-field gradient nuclear magnetic resonance (PFG NMR) technique is used to probe the diffusion of several probe molecules, i.e., water, xylenes and 1,3,5-triisopropylbenzene (TIPB), within the UiO-66 MOF and its derivatives (UiO-66NH2 and UiO-66Br). Exploiting differences in the size of probe molecules we were able to probe the diffusion rate selectively in the different pore environments of the MOFs. In particular, when relatively small molecules, such as water and small hydrocarbons, were used as probes, the PFG NMR log attenuation plots were non-linear with two distinctive diffusion regions, suggesting faster diffusion in the inter-crystalline space and slower diffusion within crystal aggregates, the latter occurring mostly inside the framework of the MOFs. Conversely, experiments with a larger probe molecule, i.e., TIPB, with a kinetic diameter of 0.95 nm, which makes it unable to access the framework windows of the MOF crystals, showed linear PFG NMR log attenuation plots, which indicates diffusion occurring in a single environment, most likely in the inter-crystalline space. Analysis of the apparent tortuosity values of the systems under investigation highlights the role of linker functionalisation in influencing the molecular diffusion of the probe molecules, which affects both intra-molecular interactions and pore accessibility within the MOF crystals. The findings of this work demonstrate that the diffusion behaviour of probe molecules within MOFs is influenced by the pore size, structure, functionalisation of the MOF linker and molecular interactions. Our study contributes to further advance the understanding of mass transport in MOFs by PFG NMR and provides insights that can inform the design and optimisation of MOF-based materials for various applications.

Adaptive water oxidation catalysis on a carboxylate-sulfonate ligand with low onset potential.

A water oxidation catalyst Ru-bcs (bcs = 2,2'-bipyridine-6'-carboxylate-6-sulfonate) with a hybrid ligand was reported. Ru-bcs utilizes the electron-donating properties of carboxylate ligands and the on-demand coordination feature of sulfonate ligands to enable a low onset potential of 1.21 V vs. NHE and a high TOF over 1000 s-1 at pH 7. The adaptive chemistry uncovered in this work provides new perspectives for developing molecular catalysts with high efficiency under low driving forces.

ABA-mediated regulation of rice grain quality and seed dormancy via the NF-YB1-SLRL2-bHLH144 Module.

Abscisic acid (ABA) plays a crucial role in promoting plant stress resistance and seed dormancy. However, how ABA regulates rice quality remains unclear. This study identifies a key transcription factor SLR1-like2 (SLRL2), which mediates the ABA-regulated amylose content (AC) of rice. Mechanistically, SLRL2 interacts with NF-YB1 to co-regulate Wx, a determinant of AC and rice quality. In contrast to SLR1, SLRL2 is ABA inducible but insensitive to GA. In addition, SLRL2 exhibits DNA-binding activity and directly regulates the expression of Wx, bHLH144 and MFT2. SLRL2 competes with NF-YC12 for interaction with NF-YB1. NF-YB1 also directly represses SLRL2 transcription. Genetic validation supports that SLRL2 functions downstream of NF-YB1 and bHLH144 in regulating rice AC. Thus, an NF-YB1-SLRL2-bHLH144 regulatory module is successfully revealed. Furthermore, SLRL2 regulates rice dormancy by modulating the expression of MFT2. In conclusion, this study revealed an ABA-responsive regulatory cascade that functions in both rice quality and seed dormancy.

Surface-Enriched Room-Temperature Liquid Bismuth for Catalytic CO2 Reduction.

Bismuth-based electrocatalysts are effective for carbon dioxide (CO2) reduction to formate. However, at room temperature, these materials are only available in solid state, which inevitably suffers from surface deactivation, declining current densities, and Faradaic efficiencies. Here, the formation of a liquid bismuth catalyst on the liquid gallium surface at ambient conditions is shown as its exceptional performance in the electrochemical reduction of CO2 (i.e., CO2RR). By doping a trace amount of bismuth (740 ppm atomic) in gallium liquid metal, a surface enrichment of bismuth by over 400 times (30 at%) in liquid state is obtained without atomic aggregation, achieving 98% Faradic efficiency for CO2 conversion to formate over 80 h. Ab initio molecular simulations and density functional theory calculations reveal that bismuth atoms in the liquid state are the most energetically favorable sites for the CO2RR intermediates, superior to solid Bi-sites, as well as joint GaBi-sites. This study opens an avenue for fabricating high-performing liquid-state metallic catalysts that cannot be reached by elementary metals under electrocatalytic conditions.

RGA1 regulates grain size, rice quality and seed germination in the small and round grain mutant srg5.

BACKGROUND: Generating elite rice varieties with high yield and superior quality is the main goal of rice breeding programs. Key agronomic traits, including grain size and seed germination characteristics, affect the final yield and quality of rice. The RGA1 gene, which encodes the α-subunit of rice G-protein, plays an important role in regulating rice architecture, seed size and abiotic stress responses. However, whether RGA1 is involved in the regulation of rice quality and seed germination traits is still unclear. RESULTS: In this study, a rice mutant small and round grain 5 (srg5), was identified in an EMS-induced rice mutant library. Systematic analysis of its major agronomic traits revealed that the srg5 mutant exhibited a semi-dwarf plant height with small and round grain and reduced panicle length. Analysis of the physicochemical properties of rice showed that the difference in rice eating and cooking quality (ECQ) between the srg5 mutant and its wild-type control was small, but the appearance quality was significantly improved. Interestingly, a significant suppression of rice seed germination and shoot growth was observed in the srg5 mutant, which was mainly related to the regulation of ABA metabolism. RGA1 was identified as the candidate gene for the srg5 mutant by BSA analysis. A SNP at the splice site of the first intron disrupted the normal splicing of the RGA1 transcript precursor, resulting in a premature stop codon. Additional linkage analysis confirmed that the target gene causing the srg5 mutant phenotype was RGA1. Finally, the introduction of the RGA1 mutant allele into two indica rice varieties also resulted in small and round rice grains with less chalkiness. CONCLUSIONS: These results indicate that RGA1 is not only involved in the control of rice architecture and grain size, but also in the regulation of rice quality and seed germination. This study sheds new light on the biological functions of RGA1, thereby providing valuable information for future systematic analysis of the G-protein pathway and its potential application in rice breeding programs.

Extraction of 5-Hydroxymethylfurfural and Furfural in Aqueous Biphasic Systems: A COSMO-RS Guided Approach to Greener Solvent Selection.

5-Hydroxymethylfurfural (HMF) and furfural (Fur) are promising biobased platform chemicals, derived from the dehydration of carbohydrate feedstocks, normally conducted in an aqueous phase. Plagued by side-reactions in such phase, such as the rehydration to levulinic acid (LA) and formic acid (FA) or self-condensation to humins, HMF and Fur necessitates diversification from monophasic aqueous reaction systems toward biphasic systems to mitigate undesired side-reactions. Here, a methodology based on the COnductor-like Screening MOdel for Real Solvents (COSMO-RS) method was used to screen solvent candidates based on the predicted partition coefficients (Ki). Hansen solubility parameters in conjunction with excess thermodynamic quantities determined by COSMO-RS were employed to assess solvent compatibility. Experimental validation of the COSMO-RS values highlighted only minor deviations from the predictions with root-mean-square-error (RMSE) values of HMF and Fur at 0.76 and 5.32, respectively, at 298 K. The combined effort suggested cyclohexanone, isophorone, and methyl isobutyl ketone (MIBK) as the best candidates. Finally, extraction solvent reuse demonstrated cyclohexanone suitability for HMF extraction with KHMF of 3.66 and MIBK for Fur with KFur 7.80 with consistent partitioning across four total runs. Both solvents are classified as recommended by the CHEM21 solvent selection guide, hence adding to the sustainability of the process.

High Gas Permeability in Aged Superglassy Membranes with Nanosized UiO-66-NH2 /cPIM-1 Network Fillers.

Superglassy membranes synthesised by polymers of intrinsic microporosity (PIMs) suffer from physical aging and show poor gas permeance over time, especially thin membranes, due to the fast rearrangement of nonequilibrium polymer chains. Herein, we constructed a novel PIM-1 thin film nanocomposite membrane (TFN) using nanosized UiO-66-NH2 (≈10 nm)/carboxylated PIM-1 (cPIM-1) as the composite filler. Unlike conventional fillers, which interact with the polymer only via the surface, the UiO-66-NH2 /cPIM-1 forms a stable three-dimensional (3D) network intertwining with the polymer chains, being very effective to impede chain relaxation, and thus physical aging. Nanosizing of UiO-66-NH2 was achieved by regulating the nucleation kinetics using carbon quantum dots (CQD) during the synthesis. This led to increased surface area, and hence more functional groups to bond with cPIM-1 (via hydrogen bonding between -NH2 and -COOH groups), which also improved interfacial compatibility between the 3D network and polymer chains avoiding defect formation. As a result, the novel TFN showed significantly improved performance in gas separation along with reduced aging (i.e. ≈6 % loss in CO2 permeability over 63 days); the aged membranes had a CO2 permeance of 2504 GPU and ideal selectivity values of 37.2 and 23.8 for CO2 /N2 and CO2 /CH4 , respectively.

A Facile Synthesis Route to AuPd Alloys for the Selective Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid.

Synthesis of 2,5-furandicarboxylic acid (FDCA) can be achieved via catalytic oxidation of 5-hydroxymethylfurfural (5-HMF), in which both base and catalyst play important roles. This work presents the development of a simple synthesis method (based on a commercial parent 10 wt.% Pd/C catalyst) to prepare the bimetallic AuPd alloy catalysts (i. e., AuPd/C) for selective 5-HMF oxidation to FDCA. When using the strong base of NaOH, Pd and Au cooperate to promote FDCA formation when deployed either separately (as a physical mixture of the monometallic Au/C and Pd/C catalysts) or ideally alloyed (AuPd/C), with complete 5-HMF conversion and FDCA yields of 66 % vs 77 %, respectively. However, NaOH also promoted the formation of undesired by-products, leading to poor mass balances (<81 %). Comparatively, under weak base conditions (using NaHCO3 ), an increase in Au loading in the AuPd/C catalysts enhances 5-HMF conversion and FDCA productivity (due to the enhanced carbonyl oxidation capacity) which coincides with a superior mass balances of >97 %. Yet, the excessive Pd content in the AuPd/C catalysts was not beneficial in promoting FDCA formation.

Enhancing Hydrogen Production from the Photoreforming of Lignin.

Photoreforming of lignocellulose biomass is widely recognised as a challenging but key technology for producing value-added chemicals and renewable hydrogen (H2 ). In this study, H2 production from photoreforming of organosolv lignin in a neutral aqueous solution was studied over a 0.1 wt % Pt/TiO2 (P25) catalyst with ultraviolet A (UVA) light. The H2 production from the system employing the lignin (~4.8 µmol gcat -1 h-1 ) was comparable to that using hydroxylated/methoxylated aromatic model compounds (i. e., guaiacol and phenol, 4.8-6.6 µmol gcat -1 h-1 ), being significantly lower than that from photoreforming of cellulose (~62.8 µmol gcat -1 h-1 ). Photoreforming of phenol and reaction intermediates catechol, hydroquinone and benzoquinone were studied to probe the mechanism of phenol oxidation under anaerobic photoreforming conditions with strong adsorption and electron transfer reactions lowering H2 production from the intermediates relative to that from phenol. The issues associated with catalyst poisoning and low photoreforming activity of lignins demonstrated in this paper have been mitigated by implementing a process by which the catalyst was cycled through anaerobic and aerobic conditions. This strategy enabled the periodic regeneration of the photocatalyst resulting in a threefold enhancement in H2 production from the photoreforming of lignin.

Loss of RSR1 function increases the abscisic acid content and improves rice quality performance at high temperature.

Rice starch regulator1 (RSR1) participates in the regulation of starch synthesis in rice, but it's function on starch synthesis and quality formation in response to high temperature is unknown. RSR1 mutation resulted in a significant increase in the abscisic acid (ABA) content in rice grains under both normal and high temperature, and the effect of high temperature on grain filling and quality formation of the rsr1 mutants was significantly reduced. The grain size, 1000-kernels weight, amylose content, gelatinization temperature, and starch viscosity of the rsr1 mutants were less sensitive to high temperature. Loss of RSR1 function increased the expression levels of starch synthesis-related genes and reduced their responses to high temperature to some extent. Besides, the percentage of germinated seeds from rsr1 mutants was significantly lower than that of the wild-type, and the difference was more significant under ABA treatment. The shoot lengths of the rsr1 mutants were remarkably shorter than those of the wild-type, which was further exacerbated by ABA treatment. These results indicated that loss function of RSR1 can improve rice quality performance at high temperature by moderately increasing the ABA content of rice grains, which provides theoretical significance for the cultivation of better-quality rice with high-temperature resistance.

Development of a model for granule-bound starch synthase I activity using free-energy calculations.

Starch is a branched polymer of glucose with two components, both of which have (1 â†’ 4)-α linear links and (1 â†’ 6)-α branch points: amylopectin, of high molecular weight with many short branches, and amylose, of lower molecular weight and only a few long-chain branches. Granule-bound starch synthase I (GBSSI) is one of the main enzymes controlling amylose synthesis and chain-length distribution. As production of different GBSSI mutants is time-consuming and laborious, molecular dynamics (MD) simulations are used here to predict the binding of different GBSSI mutants to a representative amylose fragment. The simulations were atomistic, with explicit solvent and docking, a method successfully used to understand the binding of wild-type GBSSI to amylose fragments. The binding of GBSSI to G5 (a pentasaccharide amylose fragment) is combined with free-energy calculations employing a thermodynamic integration method to predict the effects of mutations on enzyme activity. Ten GBSSI mutants with different enzyme activities were analyzed to find the structural and energy changes among different single amino-acid mutants and their possible relationship to starch characteristics. Comparing the structural changes and the relative binding free energy of G5 to the wild type GBSSI and GBSSI mutants, it was found that mutants with negative binding energy (lower than -2.0 kcal/mol) are more likely to have higher enzyme activity and amylose content compared to the wild type. This theoretical paper used simulations and robust free energy calculations to interpret in planta data with potential predictions as to what mutants might be generated to give desired properties. This study can be used to help develop grains with improved functional properties.

Mechanistic Study of Glucose Photoreforming over TiO2-Based Catalysts for H2 Production.

Glucose is a key intermediate in cellulose photoreforming for H2 production. This work presents a mechanistic investigation of glucose photoreforming over TiO2 and Pt/m-TiO2 catalysts. Analysis of the intermediates formed in the process confirmed the α-scission mechanism of glucose oxidation forming arabinose (Cn-1 sugar) and formic acid in the initial oxidation step. The selectivity to sugar products and formic acid differed over Pt/TiO2 and TiO2, with Pt/TiO2 showing the lower selectivity to formic acid due to enhanced adsorption/conversion of formic acid over Pt/TiO2. In situ ATR-IR spectroscopy of glucose photoreforming showed the presence of molecular formic acid and formate on the surface of both catalysts at low glucose conversions, suggesting that formic acid oxidation could dominate surface reactions in glucose photoreforming. Further in situ ATR-IR of formic acid photoreforming showed Pt-TiO2 interfacial sites to be key for formic acid oxidation as TiO2 was unable to convert adsorbed formic acid/formate. Isotopic studies of the photoreforming of formic acid in D2O (with different concentrations) showed that the source of the protons (to form H2 at Pt sites) was determined by the relative surface coverage of adsorbed water and formic acid.

From anaerobic digestion to single cell protein synthesis: A promising route beyond biogas utilization.

The accumulation of a large amount of organic solid waste and the lack of sufficient protein supply worldwide are two major challenges caused by rapid population growth. Anaerobic digestion is the main force of organic waste treatment, and the high-value utilization of its products (biogas and digestate) has been widely concerned. These products can be used as nutrients and energy sources for microorganisms such as microalgae, yeast, methane-oxidizing bacteria(MOB), and hydrogen-oxidizing bacteria(HOB) to produce single cell protein(SCP), which contributes to the achievement of sustainable development goals. This new model of energy conversion can construct a bioeconomic cycle from waste to nutritional products, which treats waste without additional carbon emissions and can harvest high-value biomass. Techno-economic analysis shows that the SCP from biogas and digestate has higher profit than biogas electricity generation, and its production cost is lower than the SCP using special raw materials as the substrate. In this review, the case of SCP-rich microorganisms using anaerobic digestion products for growth was investigated. Some of the challenges faced by the process and the latest developments were analyzed, and their potential economic and environmental value was verified.

Effects of size and surface charge on the sedimentation of nanoplastics in freshwater.

The environmental issues caused by nanoplastics (NPs) are increasingly noticeable. Environmental behavior study of the NPs could provide vital information for their environmental impact assessment. However, associations between NPs' inherent properties and their sedimentation behaviors were seldom investigated. In this study, six types of PSNPs (polystyrene nanoplastics) with different charges (positive and negative) and particle sizes (20-50 nm, 150-190 nm and 220-250 nm) were synthesized, and their sedimentations under different environmental factors, (e.g., pH value, ionic strength (IS), electrolyte type and natural organic matter) were investigated. Results displayed that both particle size and surface charge would affect the sedimentation of PSNPs. The maximum sedimentation ratio of 26.48% was obtained in positive charged PSNPs with size of 20-50 nm, while the minimum sedimentation ratio of 1.02% was obtained in negative charged PSNPs with size of 220-250 nm at pH 7.6. The pH value shift (range of 5-10) triggered negligible changes of sedimentation ratio, the average particle size and the Zeta potential. Small size PSNPs (20-50 nm) showed higher sensitivity to IS, electrolyte type and HA condition than large size PSNPs. At high IS value ( [Formula: see text]  = 30 mM or ISNaCl = 100 mM), the sedimentation ratios of the PSNPs all increased differently according to their properties, and the sedimentation promoting effect of CaCl2 was more significant on negative charged PSNPs than positive charged PSNPs. When [Formula: see text] increased from 0.9 to 9 mM, the sedimentation ratios of negative charged PSNPs increased by 0.53%-23.49%, while that of positive charged PSNPs increased by less than 10%. Besides, humic acid (HA) addition (1-10 mg/L) would lead to a stable suspension status for PSNPs in water with different degree and perhaps different mechanism due to their charge characteristics. These results showed new light on influence factor studies of NPs' sedimentation and would be helpful for further knowledge of NPs' environmental behaviors.

Current management of avascular necrosis of the metacarpal head: a comprehensive literature review.

BACKGROUND: Avascular necrosis (AVN) of the metacarpal head is a rare disease that may lead to progressive destruction of the metacarpophalangeal joint and hand function. This study aimed to describe the epidemiology, possible risk factors, clinical presentation, diagnostic workup, and treatment of the rare condition of avascular necrosis of the metacarpal head. METHODS: Articles were searched using the subject words "Dieterich disease","Mauclaire's disease", and "avascular necrosis of metacarpal head" in the PubMed and Scopus databases. Studies were retained for review after meeting the inclusion criteria. Those outcomes relevant to diagnose and assessing AVN of the metacarpal head and those related to curative management were extracted. RESULTS: The literature search revealed 45 studies with 55 patients. Although the aetiology of osteonecrosis has not been clearly delineated, AVN of the metacarpal head most commonly arises from trauma but other risk factors may also be involved. Plain radiographs are often negative and therefore likely to be missed. Early-stage osteonecrosis of the metacarpal head was best assessed using MRI. Given the rarity of this condition, there is no clear consensus on the treatment. CONCLUSIONS: Avascular necrosis of the metacarpal head should be considered in the differential diagnosis of painful metacarpophalangeal joints. An early understanding of this unusual disease will provide an optimal clinical outcome, restoring joint activity, and resolving pain. Nonoperative treatment cannot cure all patients. Surgical management is based on the patient and lesion characteristics.

Tunable hybrid zeolites prepared by partial interconversion.

Zeolite interconversion is a widely used strategy due to its unique advantages in the synthesis of some zeolites. By using a long-chain quaternary amine as both a structure-directing agent and porogen, we have produced superior catalysts, which we named Hybrid Zeolites, as their structures are made of building units of different zeolite types. The properties of these materials can be conveniently tuned, and their catalytic performance can be optimized simply by stopping the interconversion at different times. For cracking the 1,3,5-triisopropylbenzene, Hybrid Zeolites made of FAU and MFI units show a 5-fold increase in selectivity towards the desired product, that is, 1,3-diisopropylbenzene, compared to the commercial FAU, and a 7-fold increase in conversion at constant selectivity compared to MFI zeolite.

Tetrapropylammonium Hydroxide Treatment of Aged Dry Gel to Make Hierarchical TS-1 Zeolites for Catalysis.

This work presents the development and systematic study of a method to prepare hierarchical titanium silicalite-1 (TS-1) zeolites with high tetra-coordinated framework Ti species content. The new method involves (i) the synthesis of the aged dry gel by treating the zeolite precursor at 90 °C for 24 h; and (ii) the synthesis of hierarchical TS-1 by treating the aged dry gel using tetrapropylammonium hydroxide (TPAOH) solution under hydrothermal conditions. Systematic studies were conducted to understand the effect of the synthesis conditions (including the TPAOH concentration, liquid-to-solid ratio, and treatment time) on the physiochemical properties of the resulting TS-1 zeolites, and the results showed that the condition of a TPAOH concentration of 0.1 M, liquid-to-solid ratio of 1.0, and treatment time of 9 h was ideal to enable the synthesis of hierarchical TS-1 with a Si/Ti ratio of 44. Importantly, the aged dry gel was beneficial to the quick crystallization of zeolite and assembly of nanosized TS-1 crystals with a hierarchical structure (S ext = 315 m2 g-1 and V meso = 0.70 cm3 g-1, respectively) and high framework Ti Species content, making the accessible active sites ready for promoting oxidation catalysis.

Advances in mechanism and regulation of PANoptosis: Prospects in disease treatment.

PANoptosis, a new research hotspot at the moment, is a cell death pattern in which pyroptosis, apoptosis, and necroptosis all occur in the same cell population. In essence, PANoptosis is a highly coordinated and dynamically balanced programmed inflammatory cell death pathway that combines the main features of pyroptosis, apoptosis, and necroptosis. Many variables, such as infection, injury, or self-defect, may be involved in the occurrence of PANoptosis, with the assembly and activation of the PANoptosome being the most critical. PANoptosis has been linked to the development of multiple systemic diseases in the human body, including infectious diseases, cancer, neurodegenerative diseases, and inflammatory diseases. Therefore, it is necessary to clarify the process of occurrence, the regulatory mechanism of PANoptosis, and its relation to diseases. In this paper, we summarized the differences and relations between PANoptosis and the three types of programmed cell death, and emphatically expounded molecular mechanism and regulatory patterns of PANoptosis, with the expectation of facilitating the application of PANoptosis regulation in disease treatment.