Orientation and morphology control in acid-catalyzed covalent organic framework thin films.

As thin films of semiconducting covalent organic frameworks (COFs) are demonstrating utility for ambipolar electronics, channel materials in organic electrochemical transistors (OECTs), and broadband photodetectors, control and modulation of their thin film properties is paramount. In this work, an interfacial growth technique is utilized to synthesize imine TAPB-PDA COF films at both the liquid-liquid interface as well as at the liquid-solid interface on a Si/SiO2 substrate. The concentration of acetic acid catalyst in the aqueous phase is shown to significantly influence the thin film morphology of the liquid-solid growth, with concentrations below 1 M resulting in no film nucleation, concentrations of 1-4 M enabling smooth film formation, and concentrations greater than 4 M resulting in films with a higher density of particulates on the surface. Importantly, while the films grown at the liquid-liquid interface are mixed-orientation, those grown directly at the liquid-solid interface on the Si/SiO2 surface have highly oriented COF layers aligned parallel to the substrate surface. Moreover, this liquid-solid growth process affords TAPB-PDA COF thin films with p-type charge transport having a transconductance of 10 µS at a gate voltage of -0.9 V in an OECT device structure.

Continuous flow synthesis of pyridinium salts accelerated by multi-objective Bayesian optimization with active learning.

We report a human-in-the-loop implementation of the multi-objective experimental design via a Bayesian optimization platform (EDBO+) towards the optimization of butylpyridinium bromide synthesis under continuous flow conditions. The algorithm simultaneously optimized reaction yield and production rate (or space-time yield) and generated a well defined Pareto front. The versatility of EDBO+ was demonstrated by expanding the reaction space mid-campaign by increasing the upper temperature limit. Incorporation of continuous flow techniques enabled improved control over reaction parameters compared to common batch chemistry processes, while providing a route towards future automated syntheses and improved scalability. To that end, we applied the open-source Python module, nmrglue, for semi-automated nuclear magnetic resonance (NMR) spectroscopy analysis, and compared the acquired outputs against those obtained through manual processing methods from spectra collected on both low-field (60 MHz) and high-field (400 MHz) NMR spectrometers. The EDBO+ based model was retrained with these four different datasets and the resulting Pareto front predictions provided insight into the effect of data analysis on model predictions. Finally, quaternization of poly(4-vinylpyridine) with bromobutane illustrated the extension of continuous flow chemistry to synthesize functional materials.

Microwave Facilitated Covalent Organic Framework/Transition Metal Dichalcogenide Heterostructures.

Organic/inorganic heterostructures present a versatile platform for creating materials with new functionalities and hybrid properties. In particular, junctions between two dimensional materials have demonstrated utility in next generation electronic, optical, and optoelectronic devices. This work pioneers a microwave facilitated synthesis process to readily incorporate few-layer covalent organic framework (COF) films onto monolayer transition metal dichalcogenides (TMDC). Preferential microwave excitation of the monolayer TMDC flakes result in selective attachment of COFs onto the van der Waals surface with film thicknesses between 1 and 4 nm. The flexible process is extended to multiple TMDCs (MoS2, MoSe2, MoSSe) and several well-known COFs (TAPA-PDA COF, TPT-TFA-COF, and COF-5). Photoluminescence studies reveal a power-dependent defect formation in the TMDC layer, which facilitates electronic coupling between the materials at higher TMDC defect densities. This coupling results in a shift in the A-exciton peak location of MoSe2, with a red or blue shift of 50 or 19 meV, respectively, depending upon the electron donating character of the few-layer COF films. Moreover, optoelectronic devices fabricated from the COF-5/TMDC heterostructure present an opportunity to tune the PL intensity and control the interaction dynamics within inorganic/organic heterostructures.

3D-Printed Self-Healing Elastomers for Modular Soft Robotics.

Advances in materials, designs, and controls are propelling the field of soft robotics at an incredible rate; however, current methods for prototyping soft robots remain cumbersome and struggle to incorporate desirable geometric complexity. Herein, a vat photopolymerizable self-healing elastomer system capable of extreme elongations up to 1000% is presented. The material is formed from a combination of thiol/acrylate mixed chain/step-growth polymerizations and uses a combination of physical processes and dynamic-bond exchange via thioethers to achieve full self-healing capacity over multiple damage/healing cycles. These elastomers can be three dimensional (3D) printed with modular designs capable of healing together to form highly complex and large functional soft robots. Additionally, these materials show reprogrammable resting shapes and compatibility with self-healing liquid metal electronics. Using these capabilities, subcomponents with multiple internal channel systems were printed, healed together, and combined with functional liquid metals to form a high-wattage pneumatic switch and a humanoid-scale soft robotic gripper. The combination of 3D printing and self-healing elastomeric materials allows for facile production of support-free parts with extreme complexity, resulting in a paradigm shift for the construction of modular soft robotics.

Impact of iodine loading and substitution position on intersystem crossing efficiency in a series of ten methylated-meso-phenyl-BODIPY dyes.

Four core and six distyryl-extended methylated-meso-phenyl-BODIPY dyes with varying iodine content were synthesized. The influence of iodine loading and substitution position on the photophysical properties of these chromophores was evaluated. Selective iodine insertion at the 2- and 6-positions of the methylated-meso-phenyl-BODIPY core, rather than maximum iodine content, resulted in the highest intersystem crossing efficiency. Iodination of the distyryl-extended BODIPY core afforded intersystem crossing quantum yields comparable to 2,6-diiodo-BODIPY. Inclusion of an iodine at the para-meso-phenyl position generally enhanced non-radiative decay in the BODIPY excited-state, leading to lower fluorescence and intersystem crossing quantum yield values. Iodine substitution at the styryl-positions resulted in negligible changes to the excited-state dynamics. This study highlights: (1) the rate of radiative decay is similar in all ten derivatives (on the order of 1 × 108 s-1), (2) iodination of the 2,6-positions results in the greatest enhancement of intersystem crossing efficiency, (3) care must be taken when modifying the para-meso-phenyl position as it could have detrimental effects on the excited-state dynamics, (4) the excited-state is negligibly affected by iodination of the styryl groups, potentially enabling orthogonal functionalization without modifying the molecular photophysics, (5) distyryl extension of the chromophore core diminishes rates of non-radiative decay and intersystem crossing, resulting in higher fluorescence quantum yields and lower intersystem crossing yields in the π-extended derivatives compared to the core BDP derivatives, and (6) DFT calculations provide insight into the electronic and structural factors regulating intersystem crossing and vibrational relaxation in these molecules.

Resistance to fenbendazole in Ascaridia dissimilis, an important nematode parasite of turkeys.

An important factor in efficient production of poultry is management of parasites. Ascaridia dissimilis is the most prevalent small intestinal nematode parasite of turkeys with up to 100% of flocks infected. High worm burdens can cause necrotic enteritis leading to high mortality in flocks. Recently, we were made aware of multiple cases where high burdens were seen at slaughter despite the administration of anthelmintics at frequent intervals, suggesting that resistance may have evolved in A. dissimilis. To address this issue, we obtained eggs of A. dissimilis from 4 commercial turkey farms and performed controlled efficacy tests to determine if fenbendazole resistance was present. Three farms had histories of frequent use of fenbendazole and worms found at slaughter, suggesting they may have resistance, and one was an organic farm where we had no additional history other than the farm had transitioned to organic production a few years earlier. For each worm isolate there were 2 treated and 2 untreated groups containing 9 birds each, with all groups being replicated in 2 separate rooms. Birds were infected with approximately 200 infective eggs, and treated groups received fenbendazole in the water (SafeGuard Aquasol, 1 mg/kg) for 5 consecutive days starting on day 24 post-infection. One week after the last treatment birds were necropsied, intestinal contents were collected and worms enumerated. Three of the four isolates demonstrated greater than 99% efficacy, indicating they were fully susceptible to fenbendazole. However, the fourth isolate demonstrated a significantly reduced efficacy of 63.89%, indicating the presence of resistance. Interestingly, this was the organic farm, whereas the 3 farms with "suspected" resistance all turned out to be fully susceptible. Given that 1 randomly acquired isolate of A. dissimilis, out of 4 tested, demonstrated resistance in this study, fenbendazole resistance may be a much larger problem on turkey farms than is currently recognized. Additional studies are needed to determine the prevalence of resistance, as well as the economic impact that resistant A. dissimilis have on turkey production.

Assessing the Ability of Maternal Antibodies to Protect Broiler Chicks Against Colonization by Salmonella Heidelberg.

Vaccine regimes and maternal antibody protection are important in ensuring the health of poultry and critically important in decreasing contamination of poultry products with foodborne pathogens that threaten human health. Here, we assessed the role of passive immunity on the resistance of progeny to early colonization when challenged with Salmonella Heidelberg. Two broiler breeder hen flocks which had received a Salmonella vaccine regime consisting of two live attenuated and two killed vaccines during rearing were selected for study. ELISA titers were used to assess antibody levels in the parent flocks, with one low- and one high- titer flock selected for study. Progeny chicks (1 day of age) were taken from each flock and challenged with Salmonella Heidelberg at low (103) or high doses (105) at 3 days of age. At 14 days postinoculation, all birds were euthanatized and their liver, spleen, and ceca collected for culture. ELISA analysis found Flock A (30-wk flock) demonstrated higher Salmonella antibody titers in the parents as well as yolk titers in the progeny, resulting in greater early protection from colonization by Salmonella Heidelberg while Salmonella colonization rates were higher in the progeny of the older parent Flock (B) that demonstrated lower antibody titers in the parents and the yolks of the progeny. These results suggest that as the breeder hens' protective antibodies wane with age; the maternal antibody protection in their progeny also becomes less effective in preventing cecal colonization by Salmonella early in life, which has the potential for affecting the health of the bird and contamination of meat products destined for the consumer.

Evaluación de la capacidad de los anticuerpos maternos para proteger a pollos de engorde contra la colonización por Salmonella Heidelberg. Los esquemas de vacunas y la protección por anticuerpos maternos son importantes para garantizar la salud de las aves comerciales y críticamente importantes para reducir la contaminación de los productos avícolas con patógenos transmitidos a través de los alimentos que amenazan la salud humana. En este estudio, se evaluó el papel de la inmunidad pasiva en la resistencia de la progenie contra la colonización temprana cuando se la desafió con Salmonella Heidelberg. Dos parvadas de gallinas reproductoras de pollos de engorde que habían recibido un esquema de vacuna de Salmonella que consistía en dos vacunas vivas atenuadas y dos muertas durante la crianza se seleccionaron para el estudio. Los títulos de ELISA se utilizaron para evaluar los niveles de anticuerpos en las parvadas parentales y se seleccionó para el estudio una parvada con títulos bajos y una con títulos altos. La progenie (pollos de un día de edad) de cada parvada se recolectó y se desafiaron con Salmonella Heidelberg a dosis bajas (103) y altas (105), a los tres días de edad. A los 14 días posteriores a la inoculación, todas las aves se sometieron a eutanasia y se recolectaron hígado, bazo y ciego para el cultivo. El análisis por ELISA demostró que la parvada A (lote de 30 semanas) mostraba mayores títulos de anticuerpos de Salmonella en las reproductoras, así como títulos en el saco vitelino de la progenie, lo que resultó en una mayor protección temprana contra la colonización por Salmonella Heidelberg, mientras que las tasas de colonización de Salmonella fueron mayores en la progenie de la parvada de reproductoras (B) que demostró títulos de anticuerpos más bajos en las reproductoras y en el saco vitelino de la progenie. Estos resultados sugieren que a medida que los anticuerpos protectores de las gallinas reproductoras disminuyen con la edad, la protección de los anticuerpos maternos en su progenie también se vuelve menos efectiva en la prevención de la colonización cecal por Salmonella en edades tempranas, lo que tiene el potencial de afectar la salud de las aves y la contaminación de los productos cárnicos destinados al consumidor.

Metalation of a Mesoporous Three-Dimensional Covalent Organic Framework.

Constructing metalated three-dimensional (3D) covalent organic frameworks is a challenging synthetic task. Herein, we report the synthesis and characterization of a highly porous (SABET = 5083 m2 g-1) 3D COF with a record low density (0.13 g cm-3) containing π-electron conjugated dehydrobenzoannulene (DBA) units. Metalation of DBA-3D-COF 1 with Ni to produce Ni-DBA-3D-COF results in a minimal reduction in the surface area (SABET = 4763 m2 g-1) of the material due to the incorporation of the metal within the cavity of the DBA units, and retention of crystallinity. Both 3D DBA-COFs also display great uptake capacities for ethane and ethylene gas.

Luminescent Covalent Organic Frameworks Containing a Homogeneous and Heterogeneous Distribution of Dehydrobenzoannulene Vertex Units.

Finding new ways to construct crystalline multiple-component covalent organic frameworks (COFs) has become an important focus. Herein we report the synthesis of three novel COFs containing a homogeneous and heterogeneous distribution of π-conjugated dehydrobenzoannulene (DBA) vertex units. The COFs were synthesized by reacting different ratios of C3-symmetric DBA catechol monomers with C2-symmetric pyrene-2,7-diboronic acid (PDBA) to yield three COFs, Py-DBA-COF 1, Py-DBA-COF 2, and Py-MV-DBA-COF. All three materials are highly crystalline and display unique luminescent properties in the solid state.

Synthesis of Benzobisoxazole-Linked Two-Dimensional Covalent Organic Frameworks and Their Carbon Dioxide Capture Properties.

Developing novel synthetic strategies to construct crystalline polymeric materials with excellent chemical stability and high carbon capture capacity has become a challenging process. Herein, we report the synthesis of two novel 2D benzobisoxazole-linked covalent organic frameworks (BBO-COFs) utilizing C3-symmetric formyl- and C2-symmetric o-aminophenol-substituted molecular building blocks. The BBO-COFs exhibit excellent water stability, high surface areas, and great CO2 uptake capacities. This general synthetic method affords the opportunity to prepare ordered BBO-based polymeric materials for carbon capture, chemical sensing, and organic electronic applications.

Impact of transmammary-delivered meloxicam on biomarkers of pain and distress in piglets after castration and tail docking.

To investigate a novel route for providing analgesia to processed piglets via transmammary drug delivery, meloxicam was administered orally to sows after farrowing. The objectives of the study were to demonstrate meloxicam transfer from sows to piglets via milk and to describe the analgesic effects in piglets after processing through assessment of pain biomarkers and infrared thermography (IRT). Ten sows received either meloxicam (30 mg/kg) (n = 5) or whey protein (placebo) (n = 5) in their daily feedings, starting four days after farrowing and continuing for three consecutive days. During this period, blood and milk samples were collected at 12-hour intervals. On Day 5 after farrowing, three boars and three gilts from each litter were castrated or sham castrated, tail docked, and administered an iron injection. Piglet blood samples were collected immediately before processing and at predetermined times over an 84-hour period. IRT images were captured at each piglet blood collection point. Plasma was tested to confirm meloxicam concentrations using a validated high-performance liquid chromatography-mass spectrometry method. Meloxicam was detected in all piglets nursing on medicated sows at each time point, and the mean (± standard error of the mean) meloxicam concentration at castration was 568.9±105.8 ng/mL. Furthermore, ex-vivo prostaglandin E2 (PGE2) synthesis inhibition was greater in piglets from treated sows compared to controls (p = 0.0059). There was a time-by-treatment interaction for plasma cortisol (p = 0.0009), with meloxicam-treated piglets demonstrating lower cortisol concentrations than control piglets for 10 hours after castration. No differences in mean plasma substance P concentrations between treatment groups were observed (p = 0.67). Lower cranial skin temperatures on IRT were observed in placebo compared to meloxicam-treated piglets (p = 0.015). This study demonstrates the successful transfer of meloxicam from sows to piglets through milk and corresponding analgesia after processing, as evidenced by a decrease in cortisol and PGE2 levels and maintenance of cranial skin temperature.

Fragmentations observed in the reactions of α-methoxy-γ-alkoxyalkyl iodide substrates with super-electron-donors derived from 4-DMAP and N-methylbenzimidazole.

Reactions of super-electron-donors (SEDs) derived from 4-dimethylaminopyridine and from N-methylbenzimidazole with α-methoxy-γ-alkoxyalkyl iodides lead to liberation of the γ-alkoxy groups as their alcohols. This is consistent with generation of alkyl radicals from the alkyl halide precursors, and trapping of these radicals by the radical-cation of the SED, followed by a heterolytic fragmentation.