Open Sites Research Articles

Simulating water adsorption in metal–organic frameworks with open metal sites using the 12-6-4 Lennard–Jones potential

ABSTRACT Metal–organic frameworks (MOFs) with coordinatively unsaturated open metal sites (OMSs) are promising sorbent materials in atmospheric water harvesting (AWH) systems at low relative humidity (RH) due to their strong interactions with water molecules. However, accurate computational modelling of water adsorption in those materials are challenging, as standard force fields (FFs) based on the 12-6 Lennard–Jones (L–J) potential cannot properly describe the water–OMS interactions. In biomolecular simulations, the 12-6-4 L–J potential has been successfully used to model metal ion–water interactions in which the extra 1/r 4-term is for charge-induced dipole electrostatics. In this work, we adopted this strategy and used the 12-6-4 L–J potential to model water–OMS interactions in MOFs for low RH AWH applications. Without any modifications, the parameters used for aqueous metal ions were able to greatly improve the accuracy in predicting water adsorption isotherms in MOF-74, which highlights the simplicity and transferability of this method.

Remarkably Enhanced Luminol/H2O2 Chemiluminescence with Excellent Peroxidase-like Activity of FeCoNi-based Metal-Organic Xerogels for the Sensitive Detection of Dopamine.

Metal-organic gels (MOGs) are a category of metal-organic smart soft materials with large specific surface areas, loose porous structures, and open metal active sites. In this work, trimetallic Fe(III)Co(II)Ni(II)-based MOGs (FeCoNi-MOGs) were synthesized at room temperature via a simple and mild one-step procedure. Fe3+, Co2+, and Ni2+ were the three central metal ions in it, while 1,3,5-benzenetricarboxylic acid (H3BTC) served as the ligand. The solvent enclosed in it was then removed by freeze-drying to get the corresponding metal-organic xerogels (MOXs). The as-prepared FeCoNi-MOXs have excellent peroxidase-like activity and can significantly enhance luminol/H2O2 chemiluminescence (CL) by more than 3000 times, which is very effective compared with other reported MOXs. Based on the inhibitory effect of dopamine on the CL of the FeCoNi-MOXs/luminol/H2O2 system, a simple, rapid, sensitive, and selective CL method for dopamine detection was established with a linear range of 5-1000 nM and a limit of detection of 2.9 nM (LOD, S/N = 3). Furthermore, it has been effectively used for the quantitative measurement of dopamine in dopamine injections and human serum samples, with a recovery rate of 99.5-109.1%. This research brings up prospects for the application of MOXs with peroxidase-like activity in CL.

A Free Energy Decomposition Analysis: Insight into Binding Thermodynamics from Absolutely Localized Molecular Orbitals.

Traditional energy decomposition analysis (EDA) methods can provide an interpretive decomposition of non-covalent electronic binding energies. However, by definition, they neglect entropic effects and nuclear contributions to the enthalpy. With the objective of revealing the chemical origins of trends in free energies of binding, we introduce the concept of a Gibbs decomposition analysis (GDA) by coupling the absolutely localized molecular orbital treatment of electrons in non-covalent interactions with the simplest possible quantum rigid rotor-harmonic oscillator treatment of nuclear motion at finite temperature. The resulting pilot GDA is employed to decompose enthalpic and entropic contributions to the free energy of association of the water dimer, fluoride-water dimer, and water binding to an open metal site in the metal-organic framework Cu(I)-MFU-4l. The results show enthalpic trends that generally track the electronic binding energy and entropic trends that reveal the increasing price of loss of translational and rotational degrees freedom with temperature.

Hypomethylation and Overexpression of Th17-Associated Genes is a Hallmark of Intestinal CD4+ Lymphocytes in Crohn's Disease.

The development of Crohn's disease [CD] involves immune cell signalling pathways regulated by epigenetic modifications. Aberrant DNA methylation has been identified in peripheral blood and bulk intestinal tissue from CD patients. However, the DNA methylome of disease-associated intestinal CD4+ lymphocytes has not been evaluated. Genome-wide DNA methylation sequencing was performed from terminal ileum CD4+ cells from 21 CD patients and 12 age- and sex-matched controls. Data were analysed for differentially methylated CpGs [DMCs] and methylated regions [DMRs]. Integration was performed with RNA-sequencing data to evaluate the functional impact of DNA methylation changes on gene expression. DMRs were overlapped with regions of differentially open chromatin [by ATAC-seq] and CCCTC-binding factor [CTCF] binding sites [by ChIP-seq] between peripherally derived Th17 and Treg cells. CD4+ cells in CD patients had significantly increased DNA methylation compared to those from the controls. A total of 119 051 DMCs and 8113 DMRs were detected. While hypermethylated genes were mostly related to cell metabolism and homeostasis, hypomethylated genes were significantly enriched within the Th17 signalling pathway. The differentially enriched ATAC regions in Th17 cells [compared to Tregs] were hypomethylated in CD patients, suggesting heightened Th17 activity. There was significant overlap between hypomethylated DNA regions and CTCF-associated binding sites. The methylome of CD patients shows an overall dominant hypermethylation yet hypomethylation is more concentrated in proinflammatory pathways, including Th17 differentiation. Hypomethylation of Th17-related genes associated with areas of open chromatin and CTCF binding sites constitutes a hallmark of CD-associated intestinal CD4+ cells.

High-Throughput Computational Screening and Machine Learning Model for Accelerated Metal–Organic Frameworks Discovery in Toluene Vapor Adsorption

Some hazardous gases, like toluene vapor, have caused serious environmental pollution. The adsorption of toluene using metal–organic frameworks (MOFs) has been considered a useful mechanism to reduce environmental pollution. High-throughput computation using the grand canonical Monte Carlo (GCMC) approach was used to screen high-performance MOFs from the CoRE MOF database. A total of 802 MOFs are selected with a toluene uptake larger than HKUST-1 (6.34 mmol/g at 1900 Pa, 298 K) and CMOF-3b ([(L3b)Cu2]n, L3b = 4,4′,4″,4‴-(2,2′-dihydroxy-1,1′-binaphthalene-4,4′,6,6′-tetrayl)), showing the highest toluene vapor adsorption capacity (25.57 mmol/g). Approximately 80% of high-performance MOFs contain open metal sites. Further analyses of the quantitative structure–property relationships reveal that the MOF adsorption capacity for toluene could be primarily correlated with gravimetric surface area and void fraction. Moreover, using the HKUST-1 as a template, center-metal element replacement is suggested to be effective in improving toluene vapor adsorption. Finally, based on our previously proposed MOF-CGCNN algorithm, a regression model is developed to predict toluene adsorption capacity. Combined with high-throughput GCMC calculation, the machine learning model is applied to screen a larger MOF database (containing 137,953 hypothetical MOFs), which accelerates the virtual discovery of new high-performance candidate MOFs for toluene adsorption. The proposed strategy will be useful in material design or discovery for reducing toluene, thereby benefitting the environment.

Robust Zn(II)-Organic Framework for High Catalytic Activity on Cycloaddition of CO2 with Epoxides and Reversible Iodine Uptake

Increasingly serious natural disasters caused by excessive CO2 emission have given birth to a series of carbon-neutral technologies, among which the chemical transformation of CO2 catalyzed by metal–organic framework (MOF)-based catalysts has become a focus. Herein, the self-assembly of zinc(II) cation and designed flexible multifunctional ligand of 1,3-di(5,6-dicarboxylbenzimidazol-1-ylmethyl)benzene (H4DDBB) generated a highly robust microporous material of {[Zn(H2DDBB)]·2NMP}n (NUC-69) with 1D rectangle open channels (10.0 × 7.6 Å2). Because the inner wall of voids is densely functionalized by free −COOH groups, Nimidazole atoms, and tetra-coordinated open metal sites, activated NUC-69a exhibits high catalytic performance on the cycloaddition reactions of CO2 with epoxides under mild conditions with high turnover number and turnover frequency. In addition, NUC-69a can be used as an efficient iodine adsorbent with a maximum adsorption capacity of 0.94 g/g (4.26 I2 molecules per formulation unit) and 1.28 g/g (5.81 I2 molecules per formulation unit) in hexane solution and the volatilization phase. Hence, this work provides a productive insight into the design of multifunctional microporous MOFs by enhancing the types of active sites, which makes the developed materials a broader application prospect.

High-frequency fecal indicator bacteria (FIB) observations to assess water quality drivers at an enclosed beach.

Fecal indicator bacteria (FIB) are monitored at beaches to assess water quality and associated health risk from recreational exposure. However, monitoring is generally conducted infrequently (i.e. weekly or less often), potentially leading to inaccurate assessment of water quality at a beach at the time of use. While some work has shown that FIB in marine environments can vary over short (e.g. subhourly) time scales, that work has been mainly focused on 'open' beaches. 'Enclosed' beaches-those that are partially barriered from exchange with offshore water and thus have different residence times and mixing dynamics in the nearshore environment-have been less studied. Here we present results from a high-frequency (once per 30 minutes) FIB sampling event conducted within a Central California, USA, harbor over 48 hours. FIB concentrations at this enclosed site were more variable at high-frequencies than what has been reported at open beach sites. Correlation and regression analyses showed FIB concentrations were most strongly associated with chlorophyll a concentration, turbidity, wind speed, and tide level. Results indicate the importance of measuring FIB concentrations and explanatory environmental parameters at appropriate temporal resolutions when conducting water quality monitoring or source tracking studies. Overall, this work highlights how high-frequency sampling can effectively provide information about water quality dynamics at beaches of interest.

PROPHYLACTIC USE OF LOCAL ANTIBIOTICS IN OPEN FRACTURES: A SYSTEMATIC REVIEW AND META-ANALYSIS

IntroductionThe management of open long bone fractures is well described and has been standardised through a number of well-established guidelines. However, there is no consensus regarding the application of local antibiotics into the open fracture site as a means of reducing infection rates.Materials & MethodsA systematic review and meta-analysis were undertaken as per PRISMA guidelines. PROSPERO Registration CRD42022323545. PubMed, EMBASE, Scopus and CENTRAL were the databases assessed. The Newcastle Ottawa Scale and the Rob 2 Tool were used to assess bias. A qualitative synthesis of all included studies and meta-analysis of suitable subgroups was undertaken.ResultsIn total, 12 studies (11 observational, 1 RCT) assessing 2431 open fractures were included for analysis. All compared the addition of a local antibiotic therapy to a standard treatment versus the standard treatment alone. The methods of delivery were vancomycin powder (4 papers), tobramycin polymethylmethacrylate beads (4 papers), gentamicin coated intramedullary (IM) nails (2 papers), gentamicin injections (1 paper) and antibiotic released IM core cement (1 paper). The addition of vancomycin powder did not decrease infection rates in comparison to intravenous antibiotics alone (OR 1.3, 95% CI (0.75 – 2.26)). Antibiotic coated IM Nails appear to have an association with lower infection rates than standard IM Nails. PMMA antibiotics have shown varied results in reducing infection rates depending on the individual studies.ConclusionsThere are numerous methods available to deliver antibiotics locally to an open fracture site. Further high-quality research is required to provide a definitive conclusion on their efficacy irrespective of delivery method.

Lewis Acid‐Catalyzed Ring‐Opening Alcoholysis of Cyclohexene Oxide: The Role of Open Metal Sites in the Bi(III)‐based Metal‐Organic Framework SU‐101

AbstractSU‐101 was screened for the acid‐catalyzed ring‐opening alcoholysis of cyclohexene oxide. Results indicated access to open metal sites within SU‐101, a fundamental requirement (Lewis acid Bi+3 sites) for this reaction. In addition, SU‐101 exhibited high chemical stability, demonstrated by retaining its crystalline structure after the reaction. The cyclohexene conversion was estimated to be 99.8, 96.8, and 14.3 % at 40 °C for methanol, ethanol, and propanol, respectively. Also, SU‐101 demonstrated an outstanding catalytic cyclability performance for five cycles without losing catalytic activity.

Timing of pediatric pyloromyotomy on hospital length of stay

Pyloromyotomy timing is predicated upon correction of electrolyte abnormalities. Among infants who presented with normal electrolytes, we hypothesized that pyloromyotomy the evening of presentation, rather than waiting until morning, would confer shorter length of stay (LOS). This single-center retrospective cohort study included patients who underwent pyloromyotomy from 2012 to 2021. Exposure was time of operation with nighttime considered between the times of 17:00 and 06:59 and daytime between 07:00 and 16:59. A 2:1 daytime to nighttime match was performed among patients who presented with normal electrolytes with Fisher's Exact and Student's t-test for comparisons. Of 520 patients, 15 (3%) underwent pyloromyotomy overnight and were matched to 30 daytime patients. There were no differences in median age (33 days (interquartile range [IQR] 29–44) vs 32 days (IQR 25–44)), male sex (15 (100%) vs 28 (93.3%), or history of prematurity (0 (0%) vs 2 (6.7%)) for nighttime compared to daytime, respectively. Operative outcomes including conversion to open, duodenal perforation, incomplete myotomy, or surgical site infection did not differ between the groups. While the nighttime group had a significantly shorter time from presentation to operating room (OR) than the daytime group (5.3 vs 15.9 h), there were no significant differences in total LOS (45.7 vs 57.3 h, p = 0.13). For infants with hypertrophic pyloric stenosis who present with normal electrolytes, it is safe to offer operation same-day or following a night of hydration. There was no evidence of improved hospital utilization for patients undergoing pyloromyotomy the night of presentation.

Phase 1/2 study of mRNA-4359 administered alone and in combination with immune checkpoint blockade in adult participants with advanced solid tumors.

TPS2676 Background: mRNA-4359 is a lipid nanoparticle encapsulated mRNA-based cancer vaccine encoding for concatemerized program death-ligand 1 (PD-L1) and indoleamine 2,3-dioxygenase 1 (IDO1) antigens given as an intramuscular injection. These proteins are found across a wide range of cancer types. PD-L1 is a cell surface receptor expressed on both tumor and regulatory immune cells and functions as a checkpoint to inhibit T cell function, while IDO1 is an L-tryptophan metabolizing enzyme involved in T cell suppression and immune tolerance. Both are thought to impart an inhibitory tumor microenvironment which allows tumor cells to escape immune monitoring and clearance. T cells that can target PD-L1 and IDO1 are known to pre-exist in cancer patients and a recent study leveraging a peptide-based vaccine approach demonstrated they can be induced to elicit clinically meaningful and durable tumor responses in patients with metastatic melanoma when combined with PD-1 inhibition. mRNA-4359 encodes immunogenic peptides proposed to generate anti-PD-L1/IDO1-specific T-cells to kill immunosuppressive regulatory cells as well as cancer cells which express those antigens and thus tip the balance towards an inflammatory and/or immune permissive tumor microenvironment. Additionally, combination with checkpoint inhibition may further amplify this anti-tumor immunostimulatory effect, resulting in superior clinical outcomes. Methods: The primary objective of this first in human, open label Phase 1/2 study is to assess safety and tolerability, with secondary objectives to measure T cell profile changes and initial anti-tumor activity. Arm 1a entails dose escalation of mRNA-4359 monotherapy with dose levels guided by a modified continual reassessment method in participants with locally advanced/metastatic cancers, including cutaneous melanoma, non-small cell lung cancer (NSCLC), non-muscle invasive bladder cancer, head/ neck squamous cell carcinoma, microsatellite stable colorectal cancer, basal cell carcinoma or triple negative breast cancer. Arm 1b will be dose confirmatory and will run concurrently with a pharmacodynamic arm; both will assess mRNA-4359 in combination with pembrolizumab in patients with primary/secondary checkpoint inhibitor refractory locally advanced/metastatic melanoma or NSCLC. The totality of available data from these arms will be used to support determination of a recommended phase 2 dose. Arm 2 includes two single arm expansion cohorts evaluating mRNA-4359 in combination with pembrolizumab therapy in patients who have not received any prior therapy for their cancer in this setting of locally advanced/metastatic melanoma (Cohort 1) or locally advanced/metastatic NSCLC with PD-L1 TPS of ≥ 1% (Cohort 2). Study enrollment into Arm 1a has commenced in the United States and Australia with plans to open sites in Europe later in 2023. Clinical trial information: NCT05533697 .

Tenfold increase in adsorption capacity of HKUST-1 toward Congo red by producing defective MOF under controlled thermal treatment

The effort to achieve an optimal toxic dye removal adsorbent from wastewater has led to the design of new structures or the modification of existing materials. A practical method to improve the efficacy of current effective adsorbents is to create controlled structural defects to increase effective adsorption sites. Here, Quasi-HKUST, which is prepared by a thermally controlled method from HKUST-1 and has structural defects and more free open metal sites, was used as an absorbent of concord toxic dye. The findings demonstrate that Quasi-HKUST was able to achieve an adsorption capacity of 715 mg.g−1, which is about tenfold more than the original structure. The experimental results demonstrated an exothermic spontaneous mechanism for the dye adsorption process that fit the pseudo-second-order and Langmuir isotherm models. Converting MOFs to quasi-MOFs, especially in materials that are desirable adsorbents for removing pollutants, can be a turning point in improving the absorption capacity and achieving dream absorbents.

IMPACTS OF OPEN DUMPSITE LEACHATE ON SOIL ENZYMATIC ACTIVITY IN KANI-QRZHALA OPEN DUMPSITE – ERBIL CITY

The study was carried out to assess the effect of open dump site leachate on soil enzymes activity. Soil samples were collected in Kani-Qrzhala open dump site in Erbil city in four sites (Site1, Site2, Site3 and Site4) for different depths; surface ,30cm,60cm and 90 cm following the edge drainage pathway of leachate. The results of dehydrogenase, urease and catalase show a significant variation at significant levels (P⩽0.01) and (P⩽0.05) respectively. The highest rates of dehydrogenase, urease and catalase (77.69 µg TPF.g-1, 454.50 µg N.g-1, and 1.927µg H2O2.g-1), were recorded at surface point in all sites, while the lowest rates of all enzymes were recorded at 90 cm respectively, this is indicating that the soil depth adversely affected enzymes activity. Using oak tree wood and walnut shell biochar by 10% as a treatment to polluted soil, significantly increased enzymes activity. Walnut shell biochar was more suitable than oak tree wood biochar to catalase and urease activity, where urease was increased by 133.61% and catalase by 63.40%, while dehydrogenase activity was increased by 95.07% after using oak tree wood biochar which was more suitable than walnut shell biochar. This was related to the feedstock and technology production of biochar that affected on biochar structure and activity, however in this study, biochar application generally had a positive effect on enzymes activity and soil depth had an adverse effect.

Development of gold nanoparticles composite functionalized bimetallic metal-organic framework nanozymes and integrated smartphone to detection isoniazid

It is still an issue of continuous exploration to construct nanozymes with improved activity and to investigate catalytic mechanism. This study develops an open metal nodes integration strategy to prepare functionalized bimetallic metal-organic frameworks nanozymes (NMOF-CoFe1.8). Then Au nanoparticles are grown in-situ utilizing electrostatic effects to acquire composite nanozymes (Au@NMOF). Functionalization leads to deficiency of ligand in MOF and Au nanoparticles alter the surface charge to attract the chromogenic substrate with opposite charge. One-dimensional mixed-valence metal-oxygen chains with open sites inside Au@NMOF constitute sub-nanochannels with the functions of isolating external environment and transporting substances. Cobalt adsorption centers, iron and gold catalytic centers realizes the catalytic microenvironment, enhances the mass and electron transfer rate and speeds up the generation of hydroxyl radicals. The Michaelis constant of H2O2 is 0.0664 mM and of 3,3′,5,5′-tetramethylbenzidine is 0.0879 mM, which all proves its excellent activity. As non-competitive enzyme inhibitor, isoniazid forms irreversible ternary complex with the chromogenic substrate and Au@NMOF, whose inhibition constant is 0.0229 mmol. A colorimetric sensing platform with integrated smartphone based on hydrogel is constructed to detect isoniazid. The linear of isoniazid colorimetric sensing is 0.25–120 μM with the low detection limits of 0.2 μM. The assay platform is successfully applied to the human urine and serum samples assay with the recoveries of 97.0–103.72% and relative standard deviations less than 3%. It is expected to be practically applied due to its good reproducibility, feasibility and portability.

Changes of vegetation in coniferous monocultures in the context of conversion to mixed forests in 30 years – Implications for biodiversity restoration

The understorey vegetation of temperate forests harbours a major proportion of terrestrial biodiversity and fulfills an important role in ecosystem functioning. Over the past decades, temperate forest understoreys were found to change in species diversity and composition due to several anthropogenic and natural drivers. Currently, the conversion and restoration of even-aged coniferous monocultures into more diverse and mixed broad-leaved forests are major objectives of sustainable forest management in Central Europe. This forest conversion alters understorey communities and abiotic site conditions but the underlying patterns and processes are not yet fully understood. Therefore, we investigated changes in the Bavarian Spessart mountains in southwest Germany, where we re-sampled 108 semi-permanent plots from four different coniferous stand types (i.e., Norway spruce, Scots pine, Douglas fir, European larch) about 30 years after the initial assessment. On these plots, we recorded understorey vegetation and forest structure, and derived abiotic site conditions based on ecological indicator values of understorey vegetation, followed by multivariate analysis. We found changes in plant communities that point towards a decrease of soil acidity and a “thermophilization” of forest understoreys. Understorey species richness remained constant, while understorey's Shannon and Simpson diversity increased. The observed changes in forest structure explained the temporal shifts in understorey species composition. The understorey species composition did not experience a significant floristic homogenization since the 1990s. However, plant communities exhibited a reduction in species characteristic of coniferous forests and a simultaneous increase in species associated with broad-leaved forests. The increase of specialist species (closed forests and open sites) may have compensated for the detected decrease in generalist species. We conclude that the forest conversion towards mixed broad-leaved forest in the Spessart mountains of the past decades might have masked homogenization trends that are increasingly reported from Central European forest understoreys.

Guest-Induced Mutation of a Local Coordinative Structure in M-Gallate Metal–Organic Frameworks for Selective Adsorption of Ethylene from Ethane

In order to achieve efficient separation of ethylene/ethane systems, the ethylene industry urgently needs efficient adsorbents. The combination of advantages of ultra-microporous restriction and strong affinity from open adsorption sites is expected to achieve highly selective adsorption of ethylene. Herein, we systematically and deeply investigate the gas adsorption behavior of M-gallate series metal–organic framework materials (M = Co, Ni, and Mg). Combined with experimental results such as in situ diffuse reflectance infrared Fourier transform and density functional theory calculation, we successfully proposed an ethylene gas adsorption mechanism based on the local coordinative structure mutation induced by guest molecules. This mechanism suggests that when ethylene molecules are adsorbed, the electronic donor property of π electrons and the d−π feedback effect lead to a shift of the flexible phenolic hydroxyl group and spin state transitions of Co in Co-gallate, thereby exposing the Co site and enhancing the strong affinity to ethylene. The proposed mechanism provides an inspiration and theoretical basis for the subsequent development of efficient selective adsorbents for the separation of ethylene and ethane.

Defect-Mediated Synergistic Effect of POM/UiO-66(Zr) Host-Guest Catalysts for Robust Deep Desulfurization at Ambient Temperature.

Stable platforms of host-guest catalysts are indispensable in the field of heterogeneous catalysis, however, clarifying the specific effect of host remains challenging. Herein, polyoxometalate (POM) is encapsulated in three types of UiO-66(Zr) with different controlled densities of defects by the aperture opening and closing strategy at ambient-temperature. It is found that catalytic activity of POM for oxidative desulfurization (ODS) at room temperature is turned on when encapsulated in the defective UiO-66(Zr), and the sulfur oxidation efficiency shows an obvious increasing trend (from 0.34 to 10.43 mmol g-1 h-1 ) with the increased concentration of defects in UiO-66(Zr) host. The as-prepared catalyst with the most defective host displays ultrahigh performance which removed 1000ppm sulfur with exceptionally diluted oxidant at room-temperature within 25min. The turnover frequency can reach 620.0 h-1 at 30°C, which surpassed all the reported MOFs based ODS catalysts. A substantial guest/host synergistic effect mediated by the defective sites in UiO-66(Zr) is responsible for the enhancement. Density functional theory calculations reveal that OH/OH2 capped on the open Zr sites of host UiO-66(Zr) can decompose H2 O2 to OOH group and enables the formation of WVI -peroxo intermediates that determine the ODS activity.

Remotely sensed terrestrial open water evaporation

Terrestrial open water evaporation is difficult to measure both in situ and remotely yet is critical for understanding changes in reservoirs, lakes, and inland seas from human management and climatically altered hydrological cycling. Multiple satellite missions and data systems (e.g., ECOSTRESS, OpenET) now operationally produce evapotranspiration (ET), but the open water evaporation data produced over millions of water bodies are algorithmically produced differently than the main ET data and are often overlooked in evaluation. Here, we evaluated the open water evaporation algorithm, AquaSEBS, used by ECOSTRESS and OpenET against 19 in situ open water evaporation sites from around the world using MODIS and Landsat data, making this one of the largest open water evaporation validations to date. Overall, our remotely sensed open water evaporation retrieval captured some variability and magnitude in the in situ data when controlling for high wind events (instantaneous: r2 = 0.71; bias = 13% of mean; RMSE = 38% of mean). Much of the instantaneous uncertainty was due to high wind events (u > mean daily 7.5 m·s−1) when the open water evaporation process shifts from radiatively-controlled to atmospherically-controlled; not accounting for high wind events decreases instantaneous accuracy significantly (r2 = 0.47; bias = 36% of mean; RMSE = 62% of mean). However, this sensitivity minimizes with temporal integration (e.g., daily RMSE = 1.2–1.5 mm·day−1). To benchmark AquaSEBS, we ran a suite of 11 machine learning models, but found that they did not significantly improve on the process-based formulation of AquaSEBS suggesting that the remaining error is from a combination of the in situ evaporation measurements, forcing data, and/or scaling mismatch; the machine learning models were able to predict error well in and of itself (r2 = 0.74). Our results provide confidence in the remotely sensed open water evaporation data, though not without uncertainty, and a foundation by which current and future missions may build such operational data.

Tandem Hydroformylation-Aldol Condensation Reaction Enabled by Zn-MOF-74.

The tandem hydroformylation-aldol condensation (tandem HF-AC) reaction offers an efficient synthetic route to the synthesis of industrially relevant products. The addition of Zn-MOF-74 to the cobalt-catalyzed hydroformylation of 1-hexene enables tandem HF-AC under milder pressure and temperature conditions than the aldox process, where zinc salts are added to cobalt-catalyzed hydroformylation reactions to promote aldol condensation. The yield of the aldol condensation products increases by up to 17 times that of the homogeneous reaction without MOF and up to 5 times compared to the aldox catalytic system. Both Co2(CO)8 and Zn-MOF-74 are required to significantly enhance the activity of the catalytic system. Density functional theory simulations and Fourier-transform infrared experiments show that heptanal, the product of hydroformylation, adsorbs on the open metal site (OMS) of Zn-MOF-74, thereby increasing the electrophilic character of the carbonyl carbon atom and facilitating the condensation.

In Situ FTIR Spectroscopy for Scanning Accessible Active Sites in Defect-Engineered UiO-66.

Three UiO-66 samples were prepared by solvothermal synthesis using the defect engineering approach with benzoic acid as a modulator. They were characterized by different techniques and their acidic properties were assessed by FTIR spectroscopy of adsorbed CO and CD3CN. All samples evacuated at room temperature contained bridging μ3-OH groups that interacted with both probe molecules. Evacuation at 250 °C leads to the dehydroxylation and disappearance of the μ3-OH groups. Modulator-free synthesis resulted in a material with open Zr sites. They were detected by low-temperature CO adsorption on a sample evacuated at 200 °C and by CD3CN even on a sample evacuated at RT. However, these sites were lacking in the two samples obtained with a modulator. IR and Raman spectra revealed that in these cases, the Zr4+ defect sites were saturated by benzoates, which prevented their interaction with probe molecules. Finally, the dehydroxylation of all samples produced another kind of bare Zr sites that did not interact with CO but formed complexes with acetonitrile, probably due to structural rearrangement. The results showed that FTIR spectroscopy is a powerful tool for investigating the presence and availability of acid sites in UiO-66, which is crucial for its application in adsorption and catalysis.