Defect Induced Structural Transition and Lipase Immobilizatoin in Mesoporous Aluminum Metal-Organic Frameworks

The disorder to order and structural transformation are unique metal-organic framework (MOF) characters. How to adapt or control both behaviors in MOF is rarely studied. In this case, we demonstrate that our successful synthesis of [Al(OH)(PDA)]n (AlPDA-53-DEF, AlPDA-53-H, and AlPDA-68) with H2PDA = 4,4'-[1,4-phenylenebis(ethyne-2,1-diyl)]-di benzoic acid has illuminated the intricate world of Aluminum Metal-Organic Frameworks (Al-MOFs), offering profound insights into defect structures to order and transformations. AlPDA-53-DEF, in particular, revealed a fascinating interplay of various pore sizes within both micro and mesoporous regions, unveiling a unique lattice rearrangement phenomenon upon solvent desorption. Defects and disorders emerged as key orchestrators of transforming AlPDA-53-DEF, with its initially imperfect crystallinity, into the highly crystalline, hierarchically porous AlPDA-53-H.

Exploring the potential of iron-based metal-organic frameworks as peroxidase nanozymes for glucose detection with various secondary building units

Finding materials in biosensing that balance enzyme-like reactivity, stability, and affordability is essential for the future. Because of their unique peroxidase properties, including variable pore size, surface area, and Lewis acid active sites, iron-based metal-organic frameworks (MOFs) have evolved as viable possibilities. In this study, we constructed a Fe-MOF and tested its peroxidase-like activity and responsiveness toward H2O2 colorimetric techniques. Using encapsulation, we incorporated glucose oxidase into the ZIF-90 PVP MOF and conducted a sequential reaction with the Fe-MOF to detect glucose. The results showed better peroxidase catalytic activity of the MIL-88B(Fe) (1,4-NDC) MOF and similar secondary building unit (SBU) Fe-MOFs were studied in other peroxidase nanozyme studies. When combined with an enzyme-encapsulating ZIF-90 PVP MOF, they could be sequentially employed for glucose detection purposes. This study highlights the potential of nanozymes as an alternative to natural enzymes, with promising applications in biosensing and beyond.

Temporal Structures in Positron Spectra and Charge-Sign Effects in Galactic Cosmic Rays

We present the precision measurements of 11 years of daily cosmic positron fluxes in the rigidity range from 1.00 to 41.9 GV based on 3.4×10^{6} positrons collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. The positron fluxes show distinctly different time variations from the electron fluxes at short and long timescales. A hysteresis between the electron fluxes and the positron fluxes is observed with a significance greater than 5σ at rigidities below 8.5 GV. On the contrary, the positron fluxes and the proton fluxes show similar time variation. Remarkably, we found that positron fluxes are modulated more than proton fluxes with a significance greater than 5σ for rigidities below 7 GV. These continuous daily positron fluxes, together with AMS daily electron, proton, and helium fluxes over an 11-year solar cycle, provide unique input to the understanding of both the charge-sign and mass dependencies of cosmic rays in the heliosphere.

Treatment Tolerance and Toxicity in Elderly Oropharyngeal Cancer Patients and Implication on Outcomes

PURPOSE/OBJECTIVE(S)

To investigate the tolerance level and toxicity for standard of care treatment for oropharyngeal cancer (OP) in elderly patients and their impact on outcomes.

MATERIALS/METHODS

Using our in-house head and neck cancer database, we looked for non-metastatic OP cases that received definitive treatment between 1/2009-6/2020. All patients received either definitive radiation therapy (RT) +/- concomitant systemic therapy (ST), or surgery followed by adjuvant RT or RT-ST. For the elderly (age at diagnosis ≥65 years) and young (<65 years) patients, we compared treatment package time (TPT) (time from surgery to RT conclusion) for adjuvant RT, total RT duration and unplanned RT interruptions. ST details and dose/protocol modifications were also compared. We evaluated worst grade of pain and mucositis, hospitalization for non-hydration causes and febrile neutropenia (FN) during RT. Feeding tube (FT) use and weight loss were compared. The independent effect of these indicators on locoregional (LRFS), distant (DRFS) recurrence free and overall (OS) survival was assessed using multivariate analyses (MVA).

RESULTS

A cohort of 326 patients was included: 36% elderly (n = 118) and 64% young (n = 208), with no differences in AJCC stage distribution (8th), treatment received and HPV status (HPV+ve: 73% vs 74.6%; p = 0.86). In 23.6 % who received adjuvant RT, median TPT was 86 (range 72-128) and 81 (65-137) days for elderly vs young (p = 0.27); whereas in the definitive RT cases 76.4%, total RT duration was 49 days for both age groups. Overall, prescribed RT course was not completed in 4% and unplanned RT interruptions occurred in 22.8% and both were non-significant between age groups. Among the 261 patients that received ST, elderly utilized more cetuximab (26 vs 12%; p = 0.007). For those who received cisplatin, 20% of elderly had cumulative dose <200 mg/m2 compared to 6% among the younger age group (p = 0.006); and cisplatin was changed to carboplatin or cetuximab in 18% vs 8% (p = 0.019). Delayed/cancelled cycles and dose reductions were similar. There were more hospitalizations (47% vs 27%; p<0.001) and a trend for more FN (9% vs 3%; p = 0.09) with older age, while worst pain and mucositis was similar. FTs were used more in elderly patients (64% vs 50%; p = 0.02), for a median of 97 vs 64 days (p = 0.31); of which 19.5% vs 11% (p = 0.28) were inserted before RT start. However, % weight loss was non-significant. On MVA, longer RT duration, FT use and hospitalizations predicted worse LRFS and DRFS; and they were prognostic for OS in addition to TPT >90 days (p<0.05 for all). Nevertheless, elderly vs young had non-significant 3-year LRFS (91% vs 90% and 67% vs 69%), DRFS (86% vs 90% and 79% vs 81%) & OS (85% vs 81% and 39% vs 52%) for HPV+ve and HPV-ve respectively (p>0.05).

CONCLUSION

Elderly patients with OP need more multi-disciplinary supportive care when receiving RT and concurrent ST. However, survival outcomes are equivalent to younger patients. Ongoing studies should enroll more elderly candidates and stratify endpoints with age.

Sustained Releasable Copper and Zinc Biogenic Ions Co-Assembled in Metal-Organic Frameworks Reinforced Bacterial Eradication and Wound Mitigation in Diabetic Mice

The employment of metal-organic framework (MOF)-based nanomaterials has been rapidly increasing in bioapplications owing to their biocompatibility, drug degradation, tunable porosity, and intrinsic biodegradability. This evidence suggests that the multifunctional bimetallic ions can behave as remarkable candidates for infection control and wound healing. In this study, bimetallic MOFs (Zn-HKUST-1 and FolA-Zn-HKUST-1) embedded with and without folic acid were synthesized and used for tissue sealing and repairing incisional wound sites in mice models. For comparison, HKUST-1 and FolA-HKUST-1 were also synthesized. The Brunauer-Emmett-Teller (BET) surface area measured for HKUST-1, FolA-HKUST-1, Zn-HKUST-1, and FolA-Zn-HKUST-1 from N2 isotherms was found to be 1868, 1392, 1706, and 1179 m2/g, respectively. The measurements of contact angle values for Zn-HKUST-1, FolA-HKUST-1, and Zn-FolA-HKUST-1 were identified as 4.95 ± 0.8, 43.6 ± 3.4, and 60.62 ± 2.0°, respectively. For topical application in wound healing, they display a wide range of healing characteristics, including antibacterial and enhanced wound healing rates. In addition, in vitro cell migration and tubulogenic potentials were evaluated. The significant reduction in the wound gap and increased expression levels for CD31, eNOS, VEGF-A, and Ki67 were observed from immunohistological analyses to predict the angiogenesis behavior at the incision wound site. The wound healing rate was analyzed in the excisional dermal wounds of diabetic mice model in vivo. On account of antibacterial potentials and tissue-repairing characteristics of Cu2+ and Zn2+ ions, designing an innovative mixed metal ion-based biomaterial has wide applicability and is expected to modulate the growth of various gradient tissues.

Cordierite@MOFs with Easy Recovery in CO2 Cycloaddition

The objective of this research is to create monolithic heterogeneous catalysts (cordierite@MOFs) through the application of metal-organic framework (MOF) materials onto honeycomb cordierite for CO2 cycloaddition. By employing monolithic catalysts instead of powdered catalysts, the recycling and reusability of catalysts during postreaction treatment can be significantly improved.

Properties of Cosmic-Ray Sulfur and Determination of the Composition of Primary Cosmic-Ray Carbon, Neon, Magnesium, and Sulfur: Ten-Year Results from the Alpha Magnetic Spectrometer

We report the properties of primary cosmic-ray sulfur (S) in the rigidity range 2.15 GV to 3.0 TV based on 0.38×10^{6} sulfur nuclei collected by the Alpha Magnetic Spectrometer experiment (AMS). We observed that above 90 GV the rigidity dependence of the S flux is identical to the rigidity dependence of Ne-Mg-Si fluxes, which is different from the rigidity dependence of the He-C-O-Fe fluxes. We found that, similar to N, Na, and Al cosmic rays, over the entire rigidity range, the traditional primary cosmic rays S, Ne, Mg, and C all have sizeable secondary components, and the S, Ne, and Mg fluxes are well described by the weighted sum of the primary silicon flux and the secondary fluorine flux, and the C flux is well described by the weighted sum of the primary oxygen flux and the secondary boron flux. The primary and secondary contributions of the traditional primary cosmic-ray fluxes of C, Ne, Mg, and S (even Z elements) are distinctly different from the primary and secondary contributions of the N, Na, and Al (odd Z elements) fluxes. The abundance ratio at the source for S/Si is 0.167±0.006, for Ne/Si is 0.833±0.025, for Mg/Si is 0.994±0.029, and for C/O is 0.836±0.025. These values are determined independent of cosmic-ray propagation.

Temporal Structures in Electron Spectra and Charge Sign Effects in Galactic Cosmic Rays

We present the precision measurements of 11 years of daily cosmic electron fluxes in the rigidity interval from 1.00 to 41.9 GV based on 2.0×10^{8} electrons collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. The electron fluxes exhibit variations on multiple timescales. Recurrent electron flux variations with periods of 27 days, 13.5 days, and 9 days are observed. We find that the electron fluxes show distinctly different time variations from the proton fluxes. Remarkably, a hysteresis between the electron flux and the proton flux is observed with a significance of greater than 6σ at rigidities below 8.5 GV. Furthermore, significant structures in the electron-proton hysteresis are observed corresponding to sharp structures in both fluxes. This continuous daily electron data provide unique input to the understanding of the charge sign dependence of cosmic rays over an 11-year solar cycle.

A bioinspired copper-based coordination polymer for the detection of pheochromocytoma biomarkers

Oxidase-mimicking (catechol oxidase/laccase) nanozymes provide outstanding specificity in the detection of epinephrine (Epi) for the assessment of pheochromocytoma; however, epinephrine (Epi) and norepinephrine (NE) co-existing in the same systems will reduce the selectivity of the biosensor. In the current study, we synthesized copper-based coordination polymer (Cu-CP) nanozymes capable of accelerating the oxidation of Epi with high specificity. Furthermore, the Cu-CP is able to detect Epi over a wide linear range of 0.5-100 μM with a low detection limit of 0.36 μM while providing excellent stability and recyclability. Furthermore, we employed colorimetric and fluorescence signals for sequential detection of the coexistence of Epi and NE for use in tracking the treatment outcomes of patients with pheochromocytoma. Experiments using artificial urine further confirmed the efficacy of the proposed system.

Metal and Ligand Effect on the Structural Diversity of Divalent Coordination Polymers with Mixed Ligands: Evaluation for Photodegradation

Eight coordination polymers constructed from divalent metal salts, N,N^'-bis(pyridin-3-ylmethyl)terephthalamide (L), and various dicarboxylic acids are reported, affording [Co(L)(5-ter-IPA)(H₂O)₂]_n (5-tert-H₂IPA = 5-tert-butylisophthalic acid), 1, {[Co(L)(5-NO₂-IPA)]⋅2H₂O}_n (5-NO₂-H₂IPA = 5-nitroisophthalic acid), 2, {[Co(L)_0.5(5-NH₂-IPA)]⋅MeOH}_n (5-NH₂-H₂IPA = 5-aminoisophthalic acid), 3, {[Co(L)(MBA)]⋅2H₂O}_n (H₂MBA = diphenylmethane-4,4'-dicarboxylic acid), 4, {[Co(L)(SDA)]⋅H₂O}_n (H₂SDA = 4,4-sulfonyldibenzoic acid), 5, {[Co₂(L)₂(1,4-NDC)₂(H₂O)₂]⋅5H₂O}_n (1,4-H₂NDC = naphthalene-1,4-dicarboxylic acid), 6, {[Cd(L)(1,4-NDC)(H₂O)]⋅2H₂O}_n, 7, and {[Zn₂(L)₂(1,4-NDC)₂]⋅2H₂O}_n, 8, which were structurally characterized by using single-crystal X-ray diffraction. The structural types of 1-8 are subject to the metal and ligand identities, showing a 2D layer with the hcb, a 3D framework with the pcu, a 2D layer with the sql, a polycatenation of 2-fold interpenetrated 2D layer with the sql, a 2-fold interpenetrated 2D layer with the 2,6L1, a 3D framework with the cds, a 2D layer with the 2,4L1, and a 2D layer with the (10²⋅12)(10)₂(4⋅10⋅12⁴)(4) topologies, respectively. The investigation on the photodegradation of methylene blue (MB) by using complexes 1-3 reveals that the degradation efficiency may increase with increasing surface areas.

Structural Diversity of Mercury(II) Halide Complexes Containing Bis-pyridyl-bis-amide with Bulky and Angular Backbones: Ligand Effect and Metal Sensing

Hg(II) halide complexes [HgCl₂] 2L¹ [L¹ = N,N’-bis(3-pyridyl)bicyclo(2,2,2,)oct-7-ene-2,3,5,6-tetracarboxylic diamide), 1, [HgBr₂(L¹)]_n, 2, [HgI₂(L¹)], 3, [Hg₂X₄(L²)₂] [X = Cl, 4, Br, 5, and I, 6; L² = N,N’-bis(4-pyridylmethyl)bicyclo(2,2,2,)oct-7-ene-2,3,5,6-tetracarboxylic diamide] and {[HgX₂(L³)]⋅H₂O}_n [X = Cl, 7, Br, 8 and I, 9; L³ = 4,4′-oxybis(N-(pyridine-3-yl)benzamide)] are reported and structurally characterized using single-crystal X-ray diffraction analyses. The linear HgCl₂ units of complex 1 are interlinked by the L¹ ligands through Hg---N and Hg---O interactions, resulting in 1D supramolecular chains. Complex 2 shows 1D zigzag chains interlinked through the Br---Br interactions to form 1D looped supramolecular chains, while the mononuclear [HgI₂L²] molecules of 3 are interlinked through Hg---O and I---I interactions, forming 2D supramolecular layers. Complexes 4–6 are isomorphous dinuclear metallocycles, and 7–9 form isomorphous 1D zigzag chains. The roles of the ligand type and the halide anion in determining the structural diversity of 1–9 is discussed and the luminescent properties of 7–9 evaluated. Complexes 7–9 manifest stability in aqueous environments. Moreover, complexes 7 and 8 show good sensing towards Fe³⁺ ions with low detection limits and good reusability up to five cycles, revealing that the Hg-X---Fe³⁺ (X = Cl and Br) interaction may have an important role in determining the quenching effect of 7 and 8.

Properties of Daily Helium Fluxes

We present the precision measurement of 2824 daily helium fluxes in cosmic rays from May 20, 2011 to October 29, 2019 in the rigidity interval from 1.71 to 100 GV based on 7.6×10^{8} helium nuclei collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. The helium flux and the helium to proton flux ratio exhibit variations on multiple timescales. In nearly all the time intervals from 2014 to 2018, we observed recurrent helium flux variations with a period of 27 days. Shorter periods of 9 days and 13.5 days are observed in 2016. The strength of all three periodicities changes with time and rigidity. In the entire time period, we found that below ∼7  GV the helium flux exhibits larger time variations than the proton flux, and above ∼7  GV the helium to proton flux ratio is time independent. Remarkably, below 2.4 GV a hysteresis between the helium to proton flux ratio and the helium flux was observed at greater than the 7σ level. This shows that at low rigidity the modulation of the helium to proton flux ratio is different before and after the solar maximum in 2014.

Understanding Solvothermal Growth of Metal-Organic Framework Colloids for CO2 Capture Applications

A quantitative study of the synthesis of metal-organic framework (MOF) colloids via a solvothermal growth process was demonstrated using electrospray-differential mobility analysis (ES-DMA), a gas-phase electrophoresis approach. HKUST-1, a copper-based MOF (Cu-MOF), was selected as the representative MOF of the study. The effects of the synthetic parameters, including ligand concentration (C_BTC), synthetic temperature (T_s), and synthetic time (t_s) versus material properties of the Cu-MOF, were successfully characterized based on the mobility size distributions measured by ES-DMA. The results show that the mobility size of Cu-MOF was proportional to T_s, t_s, and C_BTC during the solvothermal growth. X-ray diffraction and Brunauer-Emmett-Teller analyses were employed complementarily to the ES-DMA, confirming that the increase in mobility size of Cu-MOF was correlated to the increase in crystallinity (i.e., larger specific surface area and crystallite size). The results of CO₂ pulse adsorption show that the synthesized Cu-MOF possessed a good CO₂ adsorption ability under 1 atm, 35 °C, and the cumulative amount of CO₂ uptake was proportional to the measured mobility size of Cu-MOF. The work provides a proof of concept for the controlled synthesis of MOF colloids with the support of gas-phase electrophoretic analysis, and the quantitative methodology is useful for the development of MOF-based applications in CO₂ capture and utilization.

Magnetic Responsive Release of Nitric Oxide from an MOF-Derived Fe3O4@PLGA Microsphere for the Treatment of Bacteria-Infected Cutaneous Wound

Nitric oxide (NO) is an essential endogenous signaling molecule regulating multifaceted physiological functions in the (cardio)vascular, neuronal, and immune systems. Due to the short half-life and location-/concentration-dependent physiological function of NO, translational application of NO as a novel therapeutic approach, however, awaits a strategy for spatiotemporal control on the delivery of NO. Inspired by the magnetic hyperthermia and magneto-triggered drug release featured by Fe₃O₄ conjugates, in this study, we aim to develop a magnetic responsive NO-release material (MagNORM) featuring dual NO-release phases, namely, burst and steady release, for the selective activation of NO-related physiology and treatment of bacteria-infected cutaneous wound. After conjugation of NO-delivery [Fe(μ-S-thioglycerol)(NO)₂]₂ with a metal-organic framework (MOF)-derived porous Fe₃O₄@C, encapsulation of obtained conjugates within the thermo-responsive poly(lactic-co-glycolic acid) (PLGA) microsphere completes the assembly of MagNORM. Through continuous/pulsatile/no application of the alternating magnetic field (AMF) to MagNORM, moreover, burst/intermittent/slow release of NO from MagNORM demonstrates the AMF as an ON/OFF switch for temporal control on the delivery of NO. Under continuous application of the AMF, in particular, burst release of NO from MagNORM triggers an effective anti-bacterial activity against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli). In addition to the magneto-triggered bactericidal effect of MagNORM against E. coli-infected cutaneous wound in mice, of importance, steady release of NO from MagNORM without the AMF promotes the subsequent collagen formation and wound healing in mice.

Uniform Core-Shell Microspheres of SiO2@MOF for CO2 Cycloaddition Reactions

A SiO₂@MOF core-shell microsphere for environmentally friendly applications was introduced in this study. Several types of metal-organic framework core-shell microspheres were successfully synthesized. To achieve high stability and favorable catalytic performance, modification and coating methods were necessary for optimization. The improved SiO₂@MOF core-shell microspheres were used in the cycloaddition reaction of carbon dioxide and propylene oxide. Dispersion ability was enhanced by the addition of core-shell microspheres, which also produced high catalytic activity. Accompanied with tetrabutylammonium bromide as a co-catalyst, SiO₂@ZIF-67 had a maximum conversion of 97%, and the results revealed that SiO₂@ZIF-67 could be used for 5 reaction cycles while maintaining high catalytic performance. This recycling catalyst was also reacted with a series of terminal epoxides to form corresponding cyclic carbonates with high conversion rates, indicating that SiO₂@MOF core-shell microspheres exhibit promise in the field of catalysis.

Enhanced Oral NO Delivery through Bioinorganic Engineering of Acid-Sensitive Prodrug into a Transformer-like DNIC@MOF Microrod

Nitric oxide (NO) is an endogenous gasotransmitter regulating alternative physiological processes in the cardiovascular system. To achieve translational application of NO, continued efforts are made on the development of orally active NO prodrugs for long-term treatment of chronic cardiovascular diseases. Herein, immobilization of NO-delivery [Fe₂(μ-SCH₂CH₂COOH)₂(NO)₄] (DNIC-2) onto MIL-88B, a metal-organic framework (MOF) consisting of biocompatible Fe³⁺ and 1,4-benzenedicarboxylate (BDC), was performed to prepare a DNIC@MOF microrod for enhanced oral delivery of NO. In simulated gastric fluid, protonation of the BDC linker in DNIC@MOF initiates its transformation into a DNIC@tMOF microrod, which consisted of DNIC-2 well dispersed and confined within the BDC-based framework. Moreover, subsequent deprotonation of the BDC-based framework in DNIC@tMOF under simulated intestinal conditions promotes the release of DNIC-2 and NO. Of importance, this discovery of transformer-like DNIC@MOF provides a parallel insight into its stepwise transformation into DNIC@tMOF in the stomach followed by subsequent conversion into molecular DNIC-2 in the small intestine and release of NO in the bloodstream of mice. In comparison with acid-sensitive DNIC-2, oral administration of DNIC@MOF results in a 2.2-fold increase in the oral bioavailability of NO to 65.7% in mice and an effective reduction of systolic blood pressure (SBP) to a ΔSBP of 60.9 ± 4.7 mmHg in spontaneously hypertensive rats for 12 h.

Ca2[Ti(HPO4)2(PO4)]·H2O, Ca[Ti2(H2O)(HPO3)4]·H2O, and Ti(H2PO2)3: Solid-State Oxidation via Proton-Coupled Electron Transfer

Titanium phosphorus oxides (TiPOs) are promising energy-conversion materials, but most are of tetravalent titanium (Ti^IV), with the trivalent Ti^IIIPOs less explored because of instability and obstacles in synthesis. In this study, we used a simple synthetic strategy and prepared three new Ti^IIIPOs with different phosphorus oxoanions: the phosphate Ca₂Ti(HPO₄)₂(PO₄)·H₂O (1), the phosphite CaTi₂(H₂O)(HPO₃)₄·H₂O (2), and the hypophosphite Ti(H₂PO₂)₃ (3). Each possesses different structures in one, two, and three dimensions, yet they are related to one another because of their infinite chains. Compound 1 exhibits proton-coupled electron transfer (PCET) reactivity in a solid state, losing one proton from its own HPO₄ in oxidation to yield Ca₂Ti(HPO₄)(PO₄)₂·H₂O (designated as 1_O), while compound 2 also exhibits PCET reactivity in which the octahedral core [Ti^III(H₂O)]³⁺ gives off two protons to become a titanyl unit [Ti^IV═O]²⁺ under oxidation, yielding CaTi₂O(HPO₃)₄·H₂O (2_O). Both 1_O and 2_O retain their original frameworks from before oxidation, but there are some changes in the hydrogen and Ti-O bonds that affect the IR absorption and powder X-ray diffraction patterns. Compound 3 represents the first titanium hypophosphite, and two polymorphs were discovered that show structures related to 1 and 2. This work demonstrates a simple strategy that is effective for preparing titanium(III) compounds in a pure phase; further, new findings in the pathways of solid-state PCET reactions promote a greater understanding of the self-sustaining oxidation behavior for Ti^IIIPO solid materials.

Zn(ii) and Co(ii) coordination polymers based on semi-rigid bis-pyridyl-bis-amide and angular dicarboxylate ligands: synthesis, structures and properties

Hydro(solvo)thermal reactions of N,N′-di(3-methylpyridyl)oxalamide (L1) and N,N′-di(4-methylpyridyl)oxalamide (L2) with angular dicarboxylic acids and metal salts afforded six new coordination polymers showing interesting properties.

Periodicities in the Daily Proton Fluxes from 2011 to 2019 Measured by the Alpha Magnetic Spectrometer on the International Space Station from 1 to 100 GV

We present the precision measurement of the daily proton fluxes in cosmic rays from May 20, 2011 to October 29, 2019 (a total of 2824 days or 114 Bartels rotations) in the rigidity interval from 1 to 100 GV based on 5.5×10^{9} protons collected with the Alpha Magnetic Spectrometer aboard the International Space Station. The proton fluxes exhibit variations on multiple timescales. From 2014 to 2018, we observed recurrent flux variations with a period of 27 days. Shorter periods of 9 days and 13.5 days are observed in 2016. The strength of all three periodicities changes with time and rigidity. The rigidity dependence of the 27-day periodicity is different from the rigidity dependences of 9-day and 13.5-day periods. Unexpectedly, the strength of 9-day and 13.5-day periodicities increases with increasing rigidities up to ∼10  GV and ∼20  GV, respectively. Then the strength of the periodicities decreases with increasing rigidity up to 100 GV.

The bi-metallic MOF-919 (Fe-Cu) nanozyme capable of bifunctional enzyme-mimicking catalytic activity

In this study, we report on a bi-metal organic framework, MOF-919 (Fe-Cu), capable of bifunctional-enzyme mimicking activity with oxidase- and peroxidase-like activities. The catalytic activities were examined by using o-phenylenediamine (OPD) as a chromogenic substrate to study oxidase- and peroxidase-like mimetics. Based on our findings, we developed a simple epinephrine colorimetric biosensor with a broad linear range (1-100 μM) and a low detection limit (0.298 μM). This approach provides evidence for transition metal-based pristine bi-metallic MOFs capable of reproducing both oxidase-peroxidase properties, which could be applied as new nanosensors.

Mechanistic Insight into the Synergetic Interaction of Ammonia Borane and Water on ZIF-67-Derived Co@Porous Carbon for Controlled Generation of Dihydrogen

Regarding dihydrogen as a clean and renewable energy source, ammonia borane (NH₃BH₃, AB) was considered as a chemical H₂-storage and H₂-delivery material due to its high storage capacity of dihydrogen (19.6 wt %) and stability at room temperature. To advance the development of efficient and recyclable catalysts for hydrolytic dehydrogenation of AB with parallel insight into the reaction mechanism, herein, ZIF-67-derived fcc-Co@porous carbon nano/microparticles (cZIF-67_nm/cZIF-67_μm) were explored to promote catalytic dehydrogenation of AB and generation of H_2(g). According to kinetic and computational studies, zero-order dependence on the concentration of AB, first-order dependence on the concentration of cZIF-67_nm (or cZIF-67_μm), and a kinetic isotope effect value of 2.45 (or 2.64) for H₂O/D₂O identify the Co-catalyzed cleavage of the H-OH bond, instead of the H-BH₂NH₃ bond, as the rate-determining step in the hydrolytic dehydrogenation of AB. Despite the absent evolution of H_2(g) in the reaction of cZIF-67 and AB in the organic solvents (i.e., THF or CH₃OH) or in the reaction of cZIF-67 and water, Co-mediated activation of AB and formation of a Co-H intermediate were evidenced by theoretical calculation, infrared spectroscopy in combination with an isotope-labeling experiment, and reactivity study toward CO₂-to-formate/H₂O-to-H₂ conversion. Moreover, the computational study discovers a synergistic interaction between AB and the water cluster (H₂O)₉ on fcc-Co, which shifts the splitting of water into an exergonic process and lowers the thermodynamic barrier for the generation and desorption of H_2(g) from the Co-H intermediates. With the kinetic and mechanistic study of ZIF-67-derived Co@porous carbon for catalytic hydrolysis of AB, the spatiotemporal control on the generation of H_2(g) for the treatment of inflammatory diseases will be further investigated in the near future.

Erratum: Properties of a New Group of Cosmic Nuclei: Results from the Alpha Magnetic Spectrometer on Sodium, Aluminum, and Nitrogen [Phys. Rev. Lett. 127, 021101 (2021)]

This corrects the article DOI: 10.1103/PhysRevLett.127.021101.

Computational and Experimental Assessments of Magnolol as a Neuroprotective Agent and Utilization of UiO-66(Zr) as Its Drug Delivery System

The phenolic natural product magnolol exhibits neuroprotective properties through β-amyloid toxicity in PC-12 cells and ameliorative effects against cognitive deficits in a TgCRND8 transgenic mice model. Its bioavailability and blood-brain barrier crossing ability have been significantly improved using the metal-organic framework (MOF) UiO-66(Zr) as a drug delivery system (DDS). To investigate the neuroprotective effects of the Zr-based DDS, magnolol and magnolol-loaded-UiO-66(Zr) (Mag@UiO-66(Zr)) were evaluated for inhibitory activity against β-secretase and AlCl₃-induced neurotoxicity. Due to the moderate inhibition observed for magnolol in vitro, in silico binding studies were explored against β-secretase along with 11 enzymes known to affect Alzheimer's disease (AD). Favorable binding energies against CDK2, CKD5, MARK, and phosphodiesterase 3B (PDE3B) and dynamically stable complexes were noted through molecular docking and molecular dynamic simulation experiments, respectively. The magnolol-loaded DDS UiO-66(Zr) also showed enhanced neuroprotective activity against two pathological indices, namely, neutrophil infiltration and apoptotic neurons, in addition to damage reversal compared to magnolol. Thus, MOFs are promising drug delivery platforms for poorly bioavailable drugs.

[Genetic analysis of 45 patients with suspected Lynch syndrome using next-generation sequencing]

Objective: To evaluate the value of next generation sequencing (NGS) in the genetic testing of Lynch syndrome. Methods: Immunohistochemical method was used to detect the expressions of DNA mismatch repair (MMR) proteins, including MutL homolog 1 (MLH1), PMS1 homolog 2 (PMS2), MutS homolog 2 (MSH2) and MutS homolog 6 (MSH6) in colorectal cancer, gastric cancer and endometrial cancer tissues collected from Shandong Provincial Hospital between 2016 and 2018. The genomic DNA of 45 patients who were suspected with Lynch syndrome was extracted from non-cancerous tissue paraffin samples, which were postoperatively confirmed by microscope. The mutations of 12 genes including MLH1 and MSH2 were detected using NGS. The germline mutant sites and significance were analyzed by bioinformatics technology and further confirmed by using Sanger sequencing. Results: The immunohistochemical results showed that the 45 cases of suspected Lynch syndrome included 22 cases of MLH1 and PMS2 deficient expression, 16 cases of MLH2 and MSH6 deficient expression, and 7 cases of MMR proteins normal expression. The NGS result showed that 28 cases of adjacent sample from colon cancer patients included 4 cases of MLH1 pathogenic mutation, 1 case of suspected MLH1 mutation, 2 cases of MLH2 pathogenic mutation, 2 cases of suspected MLH2 mutation. No MMR gene mutation was found in adjacent samples of 6 cases of rectal cancer, 6 cases of gastric cancer and 7 cases of colorectal cancer with MMR normal expression. One case of MLH1 or MHL2 pathogenic mutation and one case of MLH1 suspected mutation was detected in adjacent samples of 5 cases of endometrial cancer. Moreover, NGS also detected many other genes mutations and unreported gene mutation sites. Pathogenic and suspected MLH1 and MSH2 mutations were verified by Sanger sequencing. Conclusions: High-throughput NGS is a quick, accurate and reliable technique to identify gene variants in suspected Lynch syndrome patients. It has a wide application prospect for gene testing of tumors associated with Lynch syndrome.

Properties of a New Group of Cosmic Nuclei: Results from the Alpha Magnetic Spectrometer on Sodium, Aluminum, and Nitrogen

We report the properties of sodium (Na) and aluminum (Al) cosmic rays in the rigidity range 2.15 GV to 3.0 TV based on 0.46 million sodium and 0.51 million aluminum nuclei collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. We found that Na and Al, together with nitrogen (N), belong to a distinct cosmic ray group. In this group, we observe that, similar to the N flux, both the Na flux and Al flux are well described by the sums of a primary cosmic ray component (proportional to the silicon flux) and a secondary cosmic ray component (proportional to the fluorine flux). The fraction of the primary component increases with rigidity for the N, Na, and Al fluxes and becomes dominant at the highest rigidities. The Na/Si and Al/Si abundance ratios at the source, 0.036±0.003 for Na/Si and 0.103±0.004 for Al/Si, are determined independent of cosmic ray propagation.

A titanium(iii) phosphite exhibits polymorph-distinct redox activity involving proton-coupled electron transfer

A novel titanium(iii) phosphite with intriguing polymorphism and solid-state proton-coupled electron transfer (PCET) oxidation is presented. The polymorphs show structure-dependent PCET reactivity, interpretable by proton distribution in channels. Combined with subsequent photoreduction, the redox cycle initiated with Ti^III can produce H₂ and transform organics.

Novel REST Truncation Mutations Causing Hereditary Gingival Fibromatosis

Hereditary gingival fibromatosis (HGF) is a rare genetic disorder featured by nonsyndromic pathological overgrowth of gingiva. The excessive gingival tissues can cause dental, masticatory, and phonetic problems, which impose severe functional and esthetic burdens on affected individuals. Due to its high recurrent rate, patients with HGF have to undergo repeated surgical procedures of gingival resection, from childhood to adulthood, which significantly compromises their quality of life. Unraveling the genetic etiology and molecular pathogenesis of HGF not only gains insight into gingival physiology and homeostasis but also opens avenues for developing potential therapeutic strategies for this disorder. Recently, mutations in REST (OMIM *600571), encoding a transcription repressor, were reported to cause HGF (GINGF5; OMIM #617626) in 3 Turkish families. However, the functions of REST in gingival homeostasis and pathogenesis of REST-associated HGF remain largely unknown. In this study, we characterized 2 HGF families and identified 2 novel REST mutations, c.2449C>T (p.Arg817*) and c.2771_2793dup (p.Glu932Lysfs*3). All 5 mutations reported to date are nonsenses or frameshifts in the last exon of REST and would presumably truncate the protein. In vitro reporter gene assays demonstrated a partial or complete loss of repressor activity for these truncated RESTs. When coexpressed with the full-length protein, the truncated RESTs impaired the repressive ability of wild-type REST, suggesting a dominant negative effect. Immunofluorescent studies showed nuclear localization of overexpressed wild-type and truncated RESTs in vitro, indicating preservation of the nuclear localization signal in shortened proteins. Immunohistochemistry demonstrated a comparable pattern of ubiquitous REST expression in both epithelium and lamina propria of normal and HGF gingival tissues despite a reduced reactivity in HGF gingiva. Results of this study confirm the pathogenicity of REST truncation mutations occurring in the last exon causing HGF and suggest the pathosis is caused by an antimorphic (dominant negative) disease mechanism.

Spatiotemporal Control of Supramolecular Polymerization and Gelation of Metal-Organic Polyhedra

In coordination-based supramolecular materials such as metallogels, simultaneous temporal and spatial control of their assembly remains challenging. Here, we demonstrate that the combination of light with acids as stimuli allows for the spatiotemporal control over the architectures, mechanical properties, and shape of porous soft materials based on metal-organic polyhedra (MOPs). First, we show that the formation of a colloidal gel network from a preformed kinetically trapped MOP solution can be triggered upon addition of trifluoroacetic acid (TFA) and that acid concentration determines the reaction kinetics. As determined by time-resolved dynamic light scattering, UV-vis absorption, and ¹H NMR spectroscopies and rheology measurements, the consequences of the increase in acid concentration are (i) an increase in the cross-linking between MOPs; (ii) a growth in the size of the colloidal particles forming the gel network; (iii) an increase in the density of the colloidal network; and (iv) a decrease in the ductility and stiffness of the resulting gel. We then demonstrate that irradiation of a dispersed photoacid generator, pyranine, allows the spatiotemporal control of the gel formation by locally triggering the self-assembly process. Using this methodology, we show that the gel can be patterned into a desired shape. Such precise positioning of the assembled structures, combined with the stable and permanent porosity of MOPs, could allow their integration into devices for applications such as sensing, separation, catalysis, or drug release.

Properties of Heavy Secondary Fluorine Cosmic Rays: Results from the Alpha Magnetic Spectrometer

Precise knowledge of the charge and rigidity dependence of the secondary cosmic ray fluxes and the secondary-to-primary flux ratios is essential in the understanding of cosmic ray propagation. We report the properties of heavy secondary cosmic ray fluorine F in the rigidity R range 2.15 GV to 2.9 TV based on 0.29 million events collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. The fluorine spectrum deviates from a single power law above 200 GV. The heavier secondary-to-primary F/Si flux ratio rigidity dependence is distinctly different from the lighter B/O (or B/C) rigidity dependence. In particular, above 10 GV, the F/Si/B/O ratio can be described by a power law R^{δ} with δ=0.052±0.007. This shows that the propagation properties of heavy cosmic rays, from F to Si, are different from those of light cosmic rays, from He to O, and that the secondary cosmic rays have two classes.

Fast multipoint immobilization of lipase through chiral L-proline on a MOF as a chiral bioreactor

In this paper, we describe the facile preparation of a chiral catalyst by the combination of the amino acid, l-proline (Pro), and the enzyme, porcine pancreas lipase (PPL), immobilized on a microporous metal-organic framework (PPL-Pro@MOF). The multipoint immobilization of PPL onto the MOF is made possible with the aid of Pro, which also provided a chiral environment for enhanced enantioselectivity. The application of the microporous MOF is pivotal in maintaining the catalytic activity of PPL, wherein it prevented the leaching of Pro during the catalytic reaction, leading to the enhanced activity of PPL. The prepared biocatalyst was applied in asymmetric carbon-carbon bond formation, demonstrating the potential of this simple approach for chemical transformations.

Properties of Iron Primary Cosmic Rays: Results from the Alpha Magnetic Spectrometer

We report the observation of new properties of primary iron (Fe) cosmic rays in the rigidity range 2.65 GV to 3.0 TV with 0.62×10^{6} iron nuclei collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. Above 80.5 GV the rigidity dependence of the cosmic ray Fe flux is identical to the rigidity dependence of the primary cosmic ray He, C, and O fluxes, with the Fe/O flux ratio being constant at 0.155±0.006. This shows that unexpectedly Fe and He, C, and O belong to the same class of primary cosmic rays which is different from the primary cosmic rays Ne, Mg, and Si class.

A new 7-diethylamino-4-hydroxycoumarin based reversible colorimetric/fluorometric probe for sequential detection of Al3+/PPi and its potential use in biodetection and bioimaging applications

A new 7-diethylamino-4-hydroxycoumarin appended acylhydrazone probe was prepared and utilized for the sequential detection of Al³⁺/PPi in a reversible off–on–off emissive manner. The various practical applications of the probe were established.

Metal Organic Framework-Polyethersulfone Composite Membrane for Iodine Capture

A variety of metal organic frameworks (MOFs) were synthesized and evaluated for their iodine adsorption capacity. Out of the MOFs tested, ZIF-8 showed the most promising result with an iodine vapor uptake of 876.6 mg/g. ZIF-8 was then incorporated into a polymer, polyethersulfone (PES), at different proportions to prepare mixed matrix membranes (MMMs), which were then used to perform further iodine adsorption experiments. With a mixing ratio of 40 wt % of ZIF-8, the iodine adsorption capacity reached 1387.6 mg/g, wherein an astounding 60% improvement in adsorption was seen with the MMMs prepared compared to the original ZIF-8 powder.

Properties of Neon, Magnesium, and Silicon Primary Cosmic Rays Results from the Alpha Magnetic Spectrometer

We report the observation of new properties of primary cosmic rays, neon (Ne), magnesium (Mg), and silicon (Si), measured in the rigidity range 2.15 GV to 3.0 TV with 1.8×10^{6}  Ne, 2.2×10^{6}  Mg, and 1.6×10^{6}  Si nuclei collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. The Ne and Mg spectra have identical rigidity dependence above 3.65 GV. The three spectra have identical rigidity dependence above 86.5 GV, deviate from a single power law above 200 GV, and harden in an identical way. Unexpectedly, above 86.5 GV the rigidity dependence of primary cosmic rays Ne, Mg, and Si spectra is different from the rigidity dependence of primary cosmic rays He, C, and O. This shows that the Ne, Mg, and Si and He, C, and O are two different classes of primary cosmic rays.

Enhanced Oral Bioavailability of the Pharmacologically Active Lignin Magnolol via Zr-Based Metal Organic Framework Impregnation

Bioavailability plays an important role in drug activity in the human body, as certain drug amounts should be present to elicit activity. However, low bioavailability of drugs leads to negligible use for human benefit. In this study, the diversely active neolignan, magnolol, was impregnated onto a Zr-based organometallic framework [Uio-66(Zr)] to increase its low bioavailability (4–5%) and to test its potential acute oral toxicity. Synthesis of Uio-66(Zr) was done through the solvothermal method while simple impregnation at different time points was used to incorporate magnolol. The loading capacity of Uio-66(Zr) at 36 h was found to be significantly higher at 72.16 ± 2.15% magnolol than in other incubation time. Based on the OECD 425 (limit test), toxicity was not observed at 2000 mg kg⁻¹ dose of mag@Uio-66(Zr) in female Sprague Dawley rats. The area under the curve (AUC) at 0–720 min of mag@Uio-66(Zr) was significantly higher than the AUC of free magnolol. Moreover, relative bioavailability increased almost two-folds using Uio-66(Zr). Unconjugated magnolol was found in the liver, kidney, and brain of rats in all treatment groups. Collectively, Uio-66(Zr) provided a higher magnolol bioavailability when used as drug carrier. Thus, utilization of Uio-66(Zr) as drug carrier is of importance for maximal use for poorly soluble and lowly bioavailable drugs.

Active Volcanism Revealed from a Seismicity Conduit in the Long-resting Tatun Volcano Group of Northern Taiwan

Abundant earthquakes clustered within a particular zone often reflect an active geological feature, such as clustering seismicity along a fault zone and a huge number of volcanic-earthquakes around the erupting conduit. Herein we perform a double-difference tomographic inversion and relocate the seismicity at the long-resting Tatun volcano group (TVG) in northern Taiwan. A dramatic improvement of the earthquake location model surprisingly show that, from 2014 to 2017, two clustered seismic zones are identified in the TVG. One major group of events (>1000) persistently clustered within a ~500 m diameter vertical conduit with a ~2 km height. The clustering seismicity conduit is just located nearby Dayoukeng, one of the strongest fumaroles in the TVG, and is connected to a fracture zone characterized by low Vp/Vs in the shallow crust. The other group of events is clustered within a sphere-like zone beneath Mt. Chihsin around the depths between 0.5 km and 2 km. Both seismic zones are probably triggered by the significantly volcanic gases and fluids ascending from the deep magma reservoir. Combined with a variety of results from literature, the seismicity conduit near the strong fumarole is the evidence for an active volcano and also identifies a likely pathway for ascending magma if the TVG erupts again in the future. But possibility of developing different magma pathways at other clustered seismic zones such as beneath Mt. Chihsin may not be totally excluded.

Carbonization and Preparation of Nitrogen-Doped Porous Carbon Materials from Zn-MOF and Its Applications

Nitrogen-doped porous carbon (NPC) materials were successfully synthesized via a Zn-containing metal-organic framework (Zn-MOF). The resulting NPC materials are characterized using various physicochemical techniques which indicated that the NPC materials obtained at different carbonization temperatures exhibited different properties. Pristine MOF morphology and pore size are retained after carbonization at particular temperatures (600 °C-NPC600 and 800 °C-NPC800). NPC800 material shows an excellent surface area 1192 m2/g, total pore volume 0.92 cm3/g and displays a higher CO2 uptake 4.71 mmol/g at 273 k and 1 bar. Furthermore, NPC600 material displays good electrochemical sensing towards H2O2. Under optimized conditions, our sensor exhibited a wide linearity range between 100 µM and 10 mM with a detection limit of 27.5 µM.

Iron and chromium MOFs as sustainable catalysts for transfer hydrogenation of carbonyl compounds and biomass conversions

Fe and Cr based MOFs (MIL-88B) act as efficient and reusable catalysts for transfer hydrogenation of carbonyl compounds including bio-derived substrates.

ESIPT-active multi-color aggregation-induced emission features of triphenylamine–salicylaldehyde-based unsymmetrical azine family

A new family of ESIPT and AIE-active triphenylamine-appended unsymmetrical azine derivatives is reported.

Properties of Cosmic Helium Isotopes Measured by the Alpha Magnetic Spectrometer

Precision measurements by the Alpha Magnetic Spectrometer (AMS) on the International Space Station of ^{3}He and ^{4}He fluxes are presented. The measurements are based on 100 million ^{4}He nuclei in the rigidity range from 2.1 to 21 GV and 18 million ^{3}He from 1.9 to 15 GV collected from May 2011 to November 2017. We observed that the ^{3}He and ^{4}He fluxes exhibit nearly identical variations with time. The relative magnitude of the variations decreases with increasing rigidity. The rigidity dependence of the ^{3}He/^{4}He flux ratio is measured for the first time. Below 4 GV, the ^{3}He/^{4}He flux ratio was found to have a significant long-term time dependence. Above 4 GV, the ^{3}He/^{4}He flux ratio was found to be time independent, and its rigidity dependence is well described by a single power law ∝R^{Δ} with Δ=-0.294±0.004. Unexpectedly, this value is in agreement with the B/O and B/C spectral indices at high energies.

P5644Hypoglycemic episodes increase the risk of ventricular arrhythmias and sudden cardiac arrest in patients with type 2 diabetes - a nationwide cohort study

Background

Hypoglycemic episode (HE) increases the risk of cardiovascular mortality. The impact of HE on the risk of sudden death remains unclear. We hypothesized that HE increases the risks of ventricular arrhythmia (VA) and sudden cardiac arrest (SCA), and that anti-diabetic agents (ADAs) causing hypoglycemia also increase the risks of VA and SCA.

Methods

Patients aged ≥20 years with newly diagnosed diabetes were identified from the Taiwan National Insurance Database. HE was defined as the presentation of hypoglycemic coma or specified/unspecified hypoglycemia. For control group, we included diabetic patients without HE, and they were frequency-matched to the HE group at a 4:1 ratio. The primary outcome was the occurrence of any event of VA (including ventricular tachycardia and fibrillation) and SCA during the defined follow-up periods. Multivariate Cox hazards regression model was used to evaluate the hazard ratio (HR) for VA or SCA.

Results

A total of 54,303 diabetic patients were screened with 1,037 of them in the HE group, and 4,148 in the control group. During a mean follow-up period of 3.3±2.5 years, 29 VA/SCA events had occurred. Compared to the control group, the HE group had a higher incidence of VA/SCA (adjusted HR: 2.42, p=0.04). Diabetic patients medicated with insulin for glycemic control increased the risk of VA/SCA compared to those without insulin (adjusted HR: 3.05, p=0.01).

Kaplan-Meier survival curves

Conclusions

HEs in patients with diabetes increased the risks of VA and SCA compared to those without. Their use of insulin also independently increased the risk of VA/SCA.

Synthesis and characterization of di-nuclear bis(benzotriazole iminophenolate) cobalt complexes: catalysis for the copolymerization of carbon dioxide with epoxides

A family of di-nuclear bis(benzotriazole iminophenolate) (BiIBTP) cobalt complexes containing diverse ancillary carboxylate derivatives have been synthesized and structurally characterized. The one-pot synthesis of the BiIBTP ligand precursor with cobalt perchlorate salt (2.0 equiv.) and carboxylic acid derivatives (2.0 or 5.0 equiv.) in the presence of triethylamine (5.0 equiv.) under refluxing methanolic solution generated bimetallic di-carboxylate Co(ii)/Co(ii) complexes [(^C83CBiIBTP)Co₂(O₂CR)₂] (R = C₆H₅ (1), C₆F₅ (2), 4-CF₃-C₆H₄ (3), 4-OMe-C₆H₄ (4), CF₃ (5)) in ≧65% yields. Interestingly, the Co(ii)/Co(iii) mixed-valence complex 6 resulted from the treatment of 1 with silver perchlorate (1.0 equiv.) as the oxidizing agent under an O₂-atmosphere in 50% yield. The crystal structure of 6 reveals an ionic and di-nuclear benzoate species composed of a cationic moiety formulated as [(^C83CBiIBTP)Co₂(O₂CC₆H₅)₂]⁺ and a counterbalanced perchlorate anion, and both metal atoms are attributed to hexa-coordinated cobalt ions with varied coordination environments. Catalysis results of CO₂/epoxide copolymerization indicated that complex 1 was more efficient than 2-6 where compound 6 was shown to be the least active. Co complex 1 incorporating benzoate coligands was demonstrated to effectively catalyze the CO₂-copolymerization of cyclohexene oxide (CHO), 4-vinyl-1,2-cyclohexene oxide or cyclopentene oxide, producing the associated CO₂-based polycarbonates with >99% carbonate repeated units under optimal conditions. Not only the controllable character of complex 1 for CO₂/CHO copolymerization is enabled, but also 1 has been shown to catalyze such a copolymerization in the "immortal" manner. Using the same di-cobalt catalyst in combination with excess ratios of neopentyl glycol (up to 150 equiv.) as the chain transfer agent could give low molecular weight poly(cyclohexene carbonate) polyols with monomodal molecular weight distributions. This work offers the facilely prepared di-nuclear cobalt complexes as catalysts for the efficient catalysis of CO₂-copolymerization.

Towards Understanding the Origin of Cosmic-Ray Electrons

Precision results on cosmic-ray electrons are presented in the energy range from 0.5 GeV to 1.4 TeV based on 28.1×10^{6} electrons collected by the Alpha Magnetic Spectrometer on the International Space Station. In the entire energy range the electron and positron spectra have distinctly different magnitudes and energy dependences. The electron flux exhibits a significant excess starting from 42.1_{-5.2}^{+5.4}  GeV compared to the lower energy trends, but the nature of this excess is different from the positron flux excess above 25.2±1.8  GeV. Contrary to the positron flux, which has an exponential energy cutoff of 810_{-180}^{+310}  GeV, at the 5σ level the electron flux does not have an energy cutoff below 1.9 TeV. In the entire energy range the electron flux is well described by the sum of two power law components. The different behavior of the cosmic-ray electrons and positrons measured by the Alpha Magnetic Spectrometer is clear evidence that most high energy electrons originate from different sources than high energy positrons.