Bending Relaxation of H2 O by Collision with Para- and Ortho-H2.

We extend our recent theoretical work on the bending relaxation of H2 O in collisions with H2 by including the three water modes of vibration coupled with rotation, as well as the rotation of H2 . Our full quantum close-coupling method (excluding the H2 vibration) is combined with a high-accuracy nine-dimensional potential energy surface. The collisions of para-H2 O and ortho-H2 O with the two spin modifications of H2 are considered and compared for several initial states of H2 O. The convergence of the results as a function of the size of the rotational basis set of the two colliders is discussed. In particular, near-resonant energy transfer between H2 O and H2 is found to control the vibrational relaxation process, with a dominant contribution of transitions with Δ j 2 = j 2 f - j 2 i ${{\rm{\Delta }}j_2 = j_2^f - j_2^i }$ = + 2 , + 4 ${ + 2, + 4}$ , j 2 i ${j_2^i }$ and j 2 f ${j_2^f }$ being respectively the H2 initial and final rotational quantum numbers. Finally, the calculated value of the H2 O bending relaxation rate coefficient at 295 K is found to be in excellent agreement with its experimental estimate.

A Rigid Bender Study of the Bending Relaxation of H2O and D2O by Collisions with Ar.

The bending relaxation of H2O and D2O by collisions with Ar is studied at the Close Coupling level. Two new 4D PES are developed for these two systems. They are tested by performing rigid rotor calculations as well as by computing the D2O-Ar bound states. The results are compared with available theoretical and experimental data. Propensity rules for the dynamics are discussed and compared to those of H2O colliding with Ne or He. The bending relaxation cross sections and rates are then calculated for these two systems. The results are analysed and compared with available experimental data.

Vibrational Relaxation of D2O Induced by Collision with He: A Rigid Bender Close Coupling Study.

The vibrational relaxation of the first excited bending state of D2O induced by collision with He is studied at the close coupling level and using the Rigid Bender approximation. A new 4D potential energy surface is calculated and reported for this system. It is then used to determine the low-lying bound states of the D2O-He van der Waals complex and to perform scattering calculations. Collision rates are determined for pure rotational transitions as well as for rovibrational transitions within the first excited bending state. The results are compared with those obtained for the collision of D2O with other noble gases such as Ne and Ar. We also analyse the differences observed with respect to the H2O+He collisions and compare our results with experiment.

Scattering resonances in the rotational excitation of HDO by Ne and normal-H2: theory and experiment.

The rotational excitation of a singly deuterated water molecule (HDO) by a heavy atom (Ne) and a light diatomic molecule (H2) is investigated theoretically and experimentally in the near-threshold regime. Crossed-molecular-beam measurements with a variable crossing angle are compared to close-coupling calculations based on high-accuracy potential energy surfaces. The two lowest rotational transitions, 000 → 101 and 000 → 111, are probed in detail and a good agreement between theory and experiment is observed for both transitions in the case of HDO + Ne, where scattering resonances are however blurred out experimentally. In the case of HDO + H2, the predicted theoretical overlapping resonances are faithfully reproduced by experiment for the 000 → 111 transition, while the calculated strong signal for the 000 → 101 transition is not detected. Future work is needed to reconcile this discrepancy.

A Comparative Study of the Cold Collisions of H2O and D2O with Ne.

The present work is dedicated to the first theoretical study of the rotationally inelastic collisions of Ne with H2O and its isotopologue D2O in an attempt to analyze the effect on the dynamics of H substitution by deuterium. To this aim two new potential energy surfaces are developed. Their quality is tested by computing the bound states of the complexes and comparing them with those most recently reported by other teams. System-specific collisional propensity rules are inferred for these two systems by analyzing the computed state-to-state cross sections at low and higher collision energy. The application of the Alexander parity index propensity rule is also discussed, and the present results are compared with those obtained for the collisions with other noble gases.

An n-Type Conjugated Oligoelectrolyte Mimics Transmembrane Electron Transport Proteins for Enhanced Microbial Electrosynthesis.

Interfacing bacteria as biocatalysts with an electrode provides the basis for emerging bioelectrochemical systems that enable sustainable energy interconversion between electrical and chemical energy. Electron transfer rates at the abiotic-biotic interface are, however, often limited by poor electrical contacts and the intrinsically insulating cell membranes. Herein, we report the first example of an n-type redox-active conjugated oligoelectrolyte, namely COE-NDI, which spontaneously intercalates into cell membranes and mimics the function of endogenous transmembrane electron transport proteins. The incorporation of COE-NDI into Shewanella oneidensis MR-1 cells amplifies current uptake from the electrode by 4-fold, resulting in the enhanced bio-electroreduction of fumarate to succinate. Moreover, COE-NDI can serve as a "protein prosthetic" to rescue current uptake in non-electrogenic knockout mutants.

Conjugated Polyelectrolyte/Bacteria Living Composites in Carbon Paper for Biocurrent Generation.

Successful practical implementation of bioelectrochemical systems (BES) requires developing affordable electrode structures that promote efficient electrical communication with microbes. Recent efforts have centered on immobilizing bacteria with organic semiconducting polymers on electrodes via electrochemical methods. This approach creates a fixed biocomposite that takes advantage of the increased electrode's electroactive surface area (EASA). Here, it is demonstrated that a biocomposite comprising the water-soluble conjugated polyelectrolyte CPE-K and electrogenic Shewanella oneidensis MR-1 can self-assemble with carbon paper electrodes, thereby increasing its biocurrent extraction by ≈6-fold over control biofilms. A ≈1.5-fold increment in biocurrent extraction is obtained for the biocomposite on carbon paper relative to the biocurrent extracted from gold-coated counterparts. Electrochemical characterization revealed that the biocomposite stabilized with the carbon paper more quickly than atop flat gold electrodes. Cross-sectional images show that the biocomposite infiltrates inhomogeneously into the porous carbon structure. Despite an incomplete penetration, the biocomposite can take advantage of the large EASA of the electrode via long-range electron transport. These results show that previous success on gold electrode platforms can be improved when using more commercially viable and easily manipulated electrode materials.

New Direct Approach for Determining the Reverse Intersystem Crossing Rate in Organic Thermally Activated Delayed Fluorescent (TADF) Emitters.

We developed a new optical method to determine the rate of reverse intersystem crossing (krISC) in thermally activated delayed fluorescent (TADF) organic chromophores using time-resolved transient absorption spectroscopy. We successfully correlated the krISC of the TADF-chromophores with device performance. Specifically, we focused on the external quantum efficiency (ηEQE) and the stability of the device at high brightness levels. It is believed that by obtaining a large krISC one may reduce the possibility of triplet-triplet annihilation (TTA) and increase the long-term stability of organic light emitting diodes (OLEDs) devices at high brightness levels (ηEQE roll-off). In this contribution, we investigate the photophysical mechanism in a series of TADF-chromophores based on carbazole or acridine derivatives as donor moieties, and triazine or benzonitrile derivatives as the acceptor moieties. We found a relationship between large krISC values and high ηEQE values at low operating voltages for the TADF-chromophores investigated. In addition, those chromophores with a larger krISC illustrated a smaller ηEQE roll-off (higher stability) at high operating voltages. These features are beneficial for superior OLEDs performing devices. Contrarily, we found that if a chromophore has a krISC ≤ 105s-1 its ηEQE is ≤5%. Such a small krISC suggests that there is no TADF effect operating in these organic systems and the molecule is not efficient in harvesting triplet excitons. Emission lifetime-based methodologies for determining the krISC were included for comparison but failed to predict the devices performance of the investigated TADF-chromophores to the same extent of our proposed methodology.

Enacting Two-Electron Transfer from a Double-Triplet State of Intramolecular Singlet Fission.

A simulation-led strategy enacts two-electron transfer between an intramolecular singlet fission chromophore (tetracyanomethylene quinoidal bithiopehene with ß,ß'-solubilizing groups) and multielectron acceptor (anthraquinone). The thermodynamic plausibility of multielectron transfer from a double-triplet state and the absorption spectra of electron transfer (ET) products were predicted using quantum chemical simulations. These predictions are consistent with experimental observations of reduced lifetimes in time-resolved fluorescence spectroscopy, changes in transmission profile, and appearance of new absorption bands in transient absorption spectroscopy, all of which support multi-ET in the QOT2/AQ mixture. The analysis suggests 2ET is favored over 1ET by a 2.5:1 ratio.

[Value of magnetic resonance imaging for diagnosis of temporomandibular joint dysfunction]. / Utilidad de la resonancia magnética para el diagnóstico de disfunción de la articulación temporomandibular.

BACKGROUND: Temporomandibular joint affection is a frequent problem in the adult population, the most common form being a series of functional alterations known as temporomandibular joint dysfunction. Magnetic resonance imaging has emerged as the most appropriate test in the assessment of the joint, primarily as a non-invasive test that allows the acquisition of images in different planes. OBJECTIVE: The study aims to reaffirm the usefulness of magnetic resonance imaging study in the evaluation of the temporomandibular joints and to demonstrate differences in age and sex of more frequently associated alterations and side effects. METHODS: A prospective, observational, descriptive study in which we evaluated the presence of joint dislocations and degenerative bone changes, degeneration and/or disc perforation and inflammatory disorders. RESULTS: In 35 patients studied, all of whom had some symptoms of joint dysfunction, with ages ranging between 37 and 65 years, and with an average of 52 years, eight were normal, in 26 patients we found associated alterations with joint dysfunction, and in 14 patients the affected side was the right and the left in 10 patients. CONCLUSION: MRI should be the study of choice for a patient with temporomandibular dysfunction symptoms, as it has demonstrated excellent visualization of the joint in different acquisition planes.

Sensing cholesterol-induced rigidity in model membranes with time-resolved fluorescence spectroscopy and microscopy.

Here, we report the characterization of cholesterol levels on membrane fluidity with a twisted intramolecular charge transfer (TICT) membrane dye, namely DI-8-ANEPPS, using fluorescence lifetime techniques such as time-correlated single photon counting (TCSPC) and fluorescence lifetime imaging microscopy (FLIM). The characterized liposomes comprised a 3 : 1 ratio of POPC and POPG, respectively, 1% DI-8-ANEPPS, and increasing cholesterol levels from 0% to 50%. Fluorescence lifetime characterization revealed that increasing the cholesterol levels from 0% to 50% increases the fluorescence lifetime of DI-8-ANEPPS from 2.36 ns to 3.65 ns, a 55% increment. Such lengthening in the fluorescence lifetime is concomitant with reduced Stokes shifts and higher quantum yield, revealing that localized excitation (LE) dominates over TICT states with increased cholesterol levels. Fluorescence anisotropy measurements revealed a less isotropic environment in the membrane upon increasing cholesterol levels, suggesting a shift from liquid-disorder (Lα) to liquid-order (LO) upon adding cholesterol. Local electrostatic and dipole characterization experiments revealed that changes in the zeta-potential (ζ-potential) and transmembrane dipole potential (Ψd) induced by changes in cholesterol levels or the POPC : POPG ratio play a minimal role in the fluorescence lifetime outcome of DI-8-ANEPPS. Instead, these results indicate that the cholesterol's effect in restricting the degree of movement of DI-8-ANEPPS dominates its photophysics over the cholesterol effect on the local dipole strength. We envision that time-resolved spectroscopy and microscopy, coupled with TICT dyes, could be a convenient tool in exploring the complex interplay between membrane lipids, sterols, and proteins and provide novel insights into membrane fluidity, organization, and function.

Conjugated Polyelectrolyte Thin Films for Pseudocapacitive Applications.

A subclass of organic semiconductors known as conjugated polyelectrolytes (CPEs) is characterized by a conjugated backbone with ionic pendant groups. The water solubility of CPEs typically hinders applications of thin films in aqueous media. Herein, it is reported that films of an anionic CPE, namely CPE-K, drop cast from water produces single-component solid-state pseudocapacitive electrodes that are insoluble in aqueous electrolyte. That X-ray diffraction experiments reveal a more structurally ordered film, relative to the as-obtained powder from chemical synthesis, and dynamic light scattering measurements show an increase in aggregate particle size with increasing [KCl] indicate that CPE-K films are insoluble because of tight interchain contacts and electrostatic screening by the electrolyte. CPE-K film electrodes can maintain 85% of their original capacitance (84 F g-1 ) at 500 A g-1 and exhibit excellent cycling stability, where a capacitance retention of 93% after 100 000 cycles at a current density of 35 A g-1 . These findings demonstrate that it is possible to use initially water soluble ionic-organic materials in aqueous electrolytes, by increasing the electrolyte concentration. This strategy can be applied to the application of conjugated polyelectrolytes in batteries, organic electrochemical transistors, and electrochemical sensors, where fast electron and ion transport are required.

Evolving Synergy Between Synthetic and Biotic Elements in Conjugated Polyelectrolyte/Bacteria Composite Improves Charge Transport and Mechanical Properties.

gLiving materials can achieve unprecedented function by combining synthetic materials with the wide range of cellular functions. Of interest are situations where the critical properties of individual abiotic and biotic elements improve via their combination. For example, integrating electroactive bacteria into conjugated polyelectrolyte (CPE) hydrogels increases biocurrent production. One observes more efficient electrical charge transport within the CPE matrix in the presence of Shewanella oneidensis MR-1 and more current per cell is extracted, compared to traditional biofilms. Here, the origin of these synergistic effects are examined. Transcriptomics reveals that genes in S. oneidensis MR-1 related to bacteriophages and energy metabolism are upregulated in the composite material. Fluorescent staining and rheological measurements before and after enzymatic treatment identified the importance of extracellular biomaterials in increasing matrix cohesion. The synergy between CPE and S. oneidensis MR-1 thus arises from initially unanticipated changes in matrix composition and bacteria adaption within the synthetic environment.

High-Performance Aqueous Supercapacitors Based on a Self-Doped n-Type Conducting Polymer.

Environmentally-benign materials play a pivotal role in advancing the scalability of energy storage devices. In particular, conjugated polymers constitute a potentially greener alternative to inorganic- and carbon-based materials. One challenge to wider implementation is the scarcity of n-doped conducting polymers to achieve full cells with high-rate performance. Herein, this work demonstrates the use of a self-doped n-doped conjugated polymer, namely poly(benzodifurandione) (PBDF), for fabricating aqueous supercapacitors. PBDF demonstrates a specific capacitance of 202 ± 3 F g-1, retaining 81% of the initial performance over 5000 cycles at 10 A g-1 in 2 m NaCl( aq ). PBDF demonstrates rate performances of up to 100 and 50 A g-1 at 1 and 2 mg cm-2, respectively. Electrochemical impedance analysis reveals a surface-mediated charge storage mechanism. Improvements can be achieved by adding reduced graphene oxide (rGO), thereby obtaining a specific capacitance of 288 ± 8 F g-1 and high-rate operation (270 A g-1). The performance of PBDF is examined in symmetric and asymmetric membrane-less cells, demonstrating high-rate performance, while retaining 83% of the initial capacitance after 100 000 cycles at 10 A g-1. PBDF thus offers new prospects for energy storage applications, showcasing both desirable performance and stability without the need for additives or binders and relying on environmentally friendly solutions.

Microencapsulation of Betalains Extracted from Garambullo (Myrtillocactus geometrizans) to Produce Active Chitosan-Polyvinyl Alcohol Films with Delayed Release of Bioactive Compounds.

Garambullo is a plant with little industrial application. However, garambullo contains betalains, photosensitive phytochemical compounds, which through microencapsulation can be used in chitosan-polyvinyl alcohol (PVOH) films for application in tomato coatings. These biopackages were characterized by physical tests, water vapor permeability, puncture tests, extension, color, differential scanning calorimetry (DCS), Fourier transform infrared (FTIR) spectroscopy, and antioxidant and antimicrobial activity analyses. The influence of the biopackages on the tomato coatings was measured using parameters such as minimum weight loss close to 2% at day 9, pH of 4.6, Brix of 5.5, titratable acidity of 1 g acid/100 mL sample, and shelf life of up to 18 days. The biopackages containing betalain microcapsules had a water vapor permeability of 2 × 10-14 g/h·m·Pa and an elongation of 5 ± 0.5%, indicating that the package did not stretch. The deformation at the breaking point for the package without and with microcapsules was 0.569 and 1.620, respectively. With respect to color, adding white microcapsules and betalains can cause the material to darken, resulting in a yellowish color. Furthermore, the phenolic content was greater for the biopackages with betalains, while there was no significant difference in the antioxidant activity since the active compounds were not released. According to the in vitro results, the inhibition of B. cinerea was achieved on the eighth day when the active compounds were released from the microcapsules. The tomato with betalains lost 2% of its weight, and B. cinerea was inhibited, extending its shelf life to 18 days. The proposed biopackages have good properties as biopolymers and inhibit the presence of B. cinerea.

In vitro antioxidant and antiproliferative activities of plants of the ethnopharmacopeia from northwest of Mexico.

BACKGROUND: The aim of this study, is to investigate the in vitro antioxidant activity, the total phenols content, the flavonoids content and the antiproliferative activity of methanolic extracts of the plants: Krameria erecta, Struthanthus palmeri, Phoradendron californicum, Senna covesii and Stegnosperma halimifolium, used by different ethnic groups from northwestern Mexico in the treatment and cure of various diseases. METHODS: The in vitro antioxidant activity was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Ferric Reducing/Antioxidant Power assay (FRAP), the total phenols content was measured by Folin-Ciocalteau assay, the flavonoids content by the AlCl(3) colorimetric method and the antiproliferative activity (line cells HeLa, RAW 264.7, M12A(k).C3.F6 and L929) using MTT method. RESULTS: The K. erecta extract showed the higher radical scavenging activity (67.88%), antioxidant activity by FRAP (1.41 mg Trolox Eq), the highest total phenols content (598.51 mg Galic Acid Eq/g extract), the highest flavonoids content (3.80 mg Quercetin Eq/g extract) and the greatest antiproliferative activity in a dose dependent manner against most Cell line evaluated. A positive correlation was found between the antioxidant activity and the flavonoids content. CONCLUSIONS: This study is the first report on the antioxidant and antiproliferative activities of the five species evaluated. The results demostrate that there is a positive correlation between antioxidant activity and the flavonoids content, indicating that these type of polyphenols could be the major contributors to the observed antioxidant activity in the evaluated plant extracts. Of the extracts evaluated, that of Krameria erecta showed the greatest antioxidant and antiproliferative activities, a discovery that makes this species a promising candidate for future research.

Recyclable Conjugated Polyelectrolyte Hydrogels for Pseudocapacitor Fabrication.

In alignment with widespread interest in carbon neutralization and sustainable practices, we disclose that conjugated polyelectrolyte (CPE) hydrogels are a type of recyclable, electrochemically stable, and environmentally friendly pseudocapacitive material for energy storage applications. By leveraging ionic-electronic coupling in a relatively fluid medium, one finds that hydrogels prepared using a fresh batch of an anionic CPE, namely, Pris-CPE-K, exhibit a specific capacitance of 32.6 ± 6.6 F g-1 in 2 M NaCl and are capable of 80% (26.1 ± 6.5 F g-1) capacitance retention after 100,000 galvanostatic charge-discharge (GCD) cycles at a current density (J) of 10 A g-1. We note that equilibration under a constant potential prior to GCD analysis leads to the K+ counterions in the CPE exchanging with Na+ and, thus, the relevant active material Pris-CPE-Na. It is possible to remove the CPE material from the electrochemical cell via extraction with water and to carry out a simple purification through dialysis to produce a recycled material, namely Re-CPE-Na. The recycling workup has no significant detrimental impact on the electrochemical performance. Specifically, Re-CPE-Na hydrogels display an initial specific capacitance of 26.3 ± 1.2 F g-1 (at 10 A g-1) and retain 77% of the capacitance after a subsequent 100,000 GCD cycles. Characterization by NMR, FTIR, and Raman spectroscopies, together with XPS and GPC measurements, revealed no change in the structure of the backbone or side chains. However, rheological measurements gave evidence of a slight loss in G' and G''. Overall, that CPE hydrogels display recyclability argues in favor of considering them as a novel materials platform for energy storage applications within an economically viable circular recycling strategy.

Water-soluble extracellular vesicle probes based on conjugated oligoelectrolytes.

We developed a series of transmembrane conjugated oligoelectrolytes (COEs) with tunable optical emissions from the UV to the near IR to address the false-positive problem when detecting nanometer-sized extracellular vesicles (EVs) by flow cytometry. The amphiphilic molecular framework of COEs is defined by a linear conjugated structure and cationic charged groups at each terminal site. Consequently, COEs have excellent water solubility and the absence of nanoaggregates at concentrations up to 50 µM, and unbound COE dyes can be readily removed through ultrafiltration. These properties enable unambiguous and simple detection of COE-labeled small EVs using flow cytometry with negligible background signals. We also demonstrated the time-lapsed tracking of small EV uptake into mammalian cells and the endogenous small EV labeling using COEs. Briefly, COEs provide a class of membrane-targeting dyes that behave as biomimetics of the lipid bilayer and a general and practical labeling strategy for nanosized EVs.

Hybrid Organic-Inorganic Perovskite Superstructures for Ultrapure Green Emissions.

All inorganic CsPbBr3 superstructures (SSs) have attracted much research interest due to their unique photophysical properties, such as their large emission red-shifts and super-radiant burst emissions. These properties are of particular interest in displays, lasers and photodetectors. Currently, the best-performing perovskite optoelectronic devices incorporate organic cations (methylammonium (MA), formamidinium (FA)), however, hybrid organic-inorganic perovskite SSs have not yet been investigated. This work is the first to report on the synthesis and photophysical characterization of APbBr3 (A = MA, FA, Cs) perovskite SSs using a facile ligand-assisted reprecipitation method. At higher concentrations, the hybrid organic-inorganic MA/FAPbBr3 nanocrystals self-assemble into SSs and produce red-shifted ultrapure green emissions, meeting the requirement of Rec. 2020 displays. We hope that this work will be seminal in advancing the exploration of perovskite SSs using mixed cation groups to further improve their optoelectronic applications.

Enabling Electron Injection for Microbial Electrosynthesis with n-Type Conjugated Polyelectrolytes.

Microbial electrosynthesis-using renewable electricity to stimulate microbial metabolism-holds the promise of sustainable chemical production. A key limitation hindering performance is slow electron-transfer rates at biotic-abiotic interfaces. Here a new n-type conjugated polyelectrolyte is rationally designed and synthesized and its use is demonstrated as a soft conductive material to encapsulate electroactive bacteria Shewanella oneidensis MR-1. The self-assembled 3D living biocomposite amplifies current uptake from the electrode ≈674-fold over controls with the same initial number of cells, thereby enabling continuous synthesis of succinate from fumarate. Such functionality is a result of the increased number of bacterial cells having intimate electronic communication with the electrode and a higher current uptake per cell. This is underpinned by the molecular design of the polymer to have an n-dopable conjugated backbone for facile reduction by the electrode and zwitterionic side chains for compatibility with aqueous media. Moreover, direct arylation polycondensation is employed instead of the traditional Stille polymerization to avoid non-biocompatible tin by-products. By demonstrating synergy between living cells with n-type organic semiconductor materials, these results provide new strategies for improving the performance of bioelectrosynthesis technologies.