Reaction Of Precursor Research Articles

Metakaolin/red mud-derived geopolymer monoliths: Novel bulk-type sorbents for lead removal from wastewaters

In this study, metakaolin and red mud were used as solid precursors to synthesize geopolymer monoliths coupling hierarchical porosity with suitable compressive strength (4.5 MPa) enabling their use as bulk-type (not powders) sorbents. Then, the lead removal ability of these novel materials was investigated under various conditions. The present work is one of the first investigations evaluating the use of red mud-containing geopolymer monoliths in the extraction of heavy metals from wastewater. Herein, metakaolin was employed as a reactive precursor to overcome the low reactivity of red mud and ensure the production of benign monolithic sorbents. The lead (II) sorption of the metakaolin/red mud sorbents was studied by varying the contact time, lead concentration, pH value and the volume of the solution. Results show that this unexplored approach, involving the use of a toxic waste to produce monolithic bodies able to treat lead-containing wastewaters, is not only feasible, but highly effective. The maximum lead removal capacity of the porous bodies reached 30.7 mg/g (at pH 5, C0 = 600 ppm) being amongst the highest values reported to date for bulk-type geopolymers. The monoliths were also successfully regenerated post-sorption without significantly affecting their performance, and this enables their reuse in multiple sorption cycles provided that a suitable desorption agent is used. These are promising results that might contribute towards the industrial deployment of clay derived geopolymers in wastewater treatment systems, while encouraging a novel and sustainable recycling strategy for the red mud waste.

Pd/Rh Dual Catalysis: Tandem Isomerization–Allylation to Access α-Quaternary Carbonyl Compounds

A dual metal approach enables the use of unsymmetrical diallyl carbonates as viable enolate precursors for allylic alkylation reactions, allowing facile access to various α-quaternary allylated aldehydes and ketones. This methodology features a regioselective Pd-catalyzed decarboxylative oxidative addition, forming an electrophilic Pd π-allyl species and releasing an allylic alkoxide, which undergoes a Rh-catalyzed isomerization to an enolate in situ. Recombination of the Pd π-allyl species and Rh-enolate nucleophile then affords the α-quaternary carbonyl compound.

Synthesis of 3‐Arylacetamides Substituted Maleimide Via Weakly Coordinating Acetamide Assisted Cross‐dehydrogenative Coupling and Their Photophysical Studies

AbstractMaleimides serve as an important synthetic precursor for various organic transformation reactions. However, maleimides have been rarely employed as coupling partners for the direct synthesis of 3‐aryl substituted maleimides via oxidative Heck‐type reaction, due to the lack of β‐hydrogen at the syn‐periplanar position. Therefore, herein, we report an efficient and highly selective synthesis of 3‐arylacetamide incorporated maleimides through the cross‐dehydrogenative coupling process using the simple and native primary acetamide as a weakly directing group with Pd(II)‐catalysis conditions. This reaction furnishes 3‐arylated maleimide derivatives in good yields with high functional group tolerance. Furthermore, 3‐arylated maleimides were transformed into synthetically important derivatives. Based on preliminary control experiments, a probable reaction mechanism has been proposed for the distal C−H bond functionalization reaction. Interesting photophysical properties of the synthesized products were also observed.

Thermodynamic Analysis of Group-III-Nitride Alloying with Yttrium by Hybrid Chemical Vapor Deposition.

Group-IIIb-transition-metal-alloyed wurtzite Group-IIIa-nitride (IIIb-IIIa-N) thin films have higher piezoelectric characteristics than binary IIIa-N for a broad range of applications in photonic, electronic, sensing, and energy harvesting systems. We perform theoretical thermodynamic analysis for the deposition and epitaxial growth of Y-alloyed GaN and AlN films by a newly introduced growth technique of hybrid chemical vapor deposition (HybCVD), which can overcome the limitations of the conventional techniques. We investigate the equilibrium vapor pressures in the source zones to determine the dominant precursors of cations for the input of the mixing zone. Then, we study the driving force for the vapor-solid phase reactions of cation precursors in the growth zone to calculate the relationship between the solid composition of YxGa1-xN and YxAl1-xN and the relative amount of input precursors (Y vs. GaCl and AlCl3) in different deposition conditions, such as temperature, V/III precursor input ratio, and H2/inert-gas mixture ratio in the carrier gas. The xY composition in YAlN changes nearly linearly with the input ratio of cation precursors regardless of the growth conditions. However, YGaN composition changes non-linearly and is also substantially affected by the conditions. The thermodynamic analysis provides insight into the chemistry involved in the epitaxial growth of IIIa-IIIb-N by the HybCVD, as well as the information for suitable growth conditions, which will guide the way for ongoing experimental efforts on the improvement of piezoelectricity of the lead-free piezoelectric materials.

Ionic Liquid-Mediated Route to Atomic Layer Deposition of Tin(II) Oxide via a C-C Bond Cleavage Ligand Modification Mechanism.

Atomic layer deposition (ALD) is a technologically important method to grow thin films with high conformality and excellent thickness control from vapor phase precursors. The development of new thermal ALD processes can be limited by precursor reactivity and stability: reaction temperature and precursor design are among the few variables available to achieve higher reactivity in gas-phase reactions, unlike in solution synthesis, where the use of solvent and/or a catalyst can promote a desired reaction. To bridge this synthesis gap between vapor-phase and solution-phase, we demonstrate the use of an ultrathin coating layer of a vapor phase-compatible solvent─an ionic liquid (IL)─on our growth substrate to perform ALD of SnO. Successful SnO deposition is achieved using tin acetylacetonate and water, a process that otherwise would require a stronger counter-reactant such as ozone. The presence of the layer of IL allows a solvent-mediated reaction mechanism to take place on the growth substrate surface. We report a growth per cycle of 0.67 Å/cycle at a deposition temperature of 100 °C in an IL comprising 1-ethyl-3-methylimidazolium hydrogen sulfate. Characterization of the ALD films confirms the SnO film composition, and 1H and 13C NMR are used to probe the solvent-mediated ALD reaction, suggesting a solvent-mediated addition-elimination-type mechanism which breaks a C-C bond in acetylacetonate to form acetone and acetate. Density functional theory calculations show that the IL solvent is beneficial to the proposed solvent-mediated mechanism by lowering the C-C bond cleavage energetics of acetylacetonate compared to the vapor phase. A general class of ligand modification reactions for thermal ALD is thus introduced in this work.

Insights into the Active Catalyst Formation from Dinuclear Palladium Acetate in Pd-Catalyzed Coupling Reactions: A DFT Study.

We studied the steps in the formation of active palladium catalyst species from palladium acetate dimer employing density functional theory calculations. We explored the possible pathways with an automated reaction search and studied the kinetics with stochastic simulation analysis. The dimeric form of palladium acetate is considered a resting state of the catalyst. Our reaction search starting from the dimeric form by sequential ligand addition resulted in experimentally observed monomeric species. We analyzed the bonding in the palladium acetate dimer and the role of Pd in the stability of the dimeric species. We implemented the Gillespie stochastic simulation algorithm to gain more insights into multichannel reaction paths and applied it to the degradation pathways. The analysis of the thermodynamic and kinetic data for these degradation pathways suggests that the dimeric form of the catalyst can be a potential catalytic precursor in the palladium acetate-catalyzed coupling reactions under the experimental reaction conditions.

Utilizing TCR-Seq to Detect Tabelecleucel, an Allogeneic Epstein-Barr Virus (EBV)-Specific T-Cell Immunotherapy, Post-Infusion

Background: Tabelecleucel is an off-the-shelf, allogeneic EBV-specific T-cell immunotherapy that targets EBV-antigen presenting cells in an HLA restricted manner. It is not genetically modified and therefore lacks a distinct universal molecular moiety to detect it post-infusion. To date, the most effective measure of EBV reactive T-cells in patients (pts) treated with tabelecleucel is the EBV-cytotoxic T lymphocyte precursor (CTLp) assay, which measures the number of EBV reactive CTL precursors in each sample but cannot distinguish between the pt's endogenous CTLs or the infused product CTLs. We have previously shown that EBV-CTLp peak correlates with pt response. Prior methods to identify circulating product CTLs have relied on differences in the genomic profiles of the pt and dosing product lot. However, the limit of detection for these assays to date has not been sensitive enough to reliably detect product CTLs post-infusion. One aspect of T-cell biology that could be utilized to track product specific CTL clones is the unique T cell receptors (TCR) which impart antigen specificity. TCRs are highly diverse and only a small minority of TCR clones are found to be shared across unrelated individuals. Therefore, we leveraged TCRβ sequencing of the CDR3 region to barcode unique TCR clones in tabelecleucel product lots and pt derived samples to detect product T cell clones post-infusion, and annotate likely EBV-targeting T cell clones based upon sequence homology to previously reported EBV-targeting TCR clones. Using this approach, we aimed to identify corollaries associated with clinical outcomes. Methods: Peripheral blood mononuclear cell samples from pts enrolled in the ALLELE (NCT03394365) study were obtained pre-dose on cycle (C) 1 day (D)1/D8/D15, C2D1/D8/D15 and at safety follow-up. EBV-CTLp was used to measure circulating EBV reactive T-cells, and both the pre-infusion baseline timepoint, and the timepoint of peak on-treatment EBV-CTL expansion were selected for downstream TCRβ sequencing. TCR repertoires for pt samples and the tabelecleucel dosing lot were assessed using TCRβ immunoSEQ assay. The captured TCR repertoires of pt samples were compared to the TCR repertoire of the dosing tabelecleucel lot to annotate product TCR clones and were compared against publicly available databases of previously identified EBV-specific TCRβ sequences to annotate putative EBV targeting TCR clones. Results: Analyses for an initial subset of 7 pts with EBV-positive post-transplant lymphoproliferative disease have been completed and are described here. Six unique tabelecleucel lots were used to treat these pts and were included in the analysis. On average 0.15 ± 0.04% of TCRs detected were shared between multiple lots, allowing the ability to leverage TCRβ sequences as a unique barcode to identify specific product lots. All 7 pts tested had TCRβ clones matching previously identified EBV-specific TCRs detected at baseline (median [min, max]: 3498 [1855, 12486]) and peak EBV-CTLp; clones detected at peak EBV-CTLp were either those previously detected at baseline (532 [129,1627]) or newly emerged (3622, [1801,5347]). TCRβ clones matching the dosing lot were identified in 6 out of 7 pts. Three pts had TCRβ clones matching the dosing lot present at baseline prior to tabelecleucel infusion (2 [1,5]). Post-infusion emergence of TCRs matching the dosing lot was detected in 5 pts (1 [1,3]). TCRβ sequencing on additional pts is currently underway. Association of post-infusion detection of dosing lot specific TCR clones with pt best overall response is ongoing and will be reported at the time of presentation. Conclusions: Utilizing TCRβ sequencing we can identify putative EBV-targeting TCR clones and dosing product TCR clones in pt TCR repertoires. Overall, an average of 12.5 ± 1.6% of captured TCR repertoires were annotated as EBV-targeting TCR clones. As publicly available reference datasets for EBV-specific TCRs are currently limited, this is likely an underrepresentation of the totality of EBV-specific TCRs present within the samples. Additionally, an average of 75.8% of the dosing product TCR clones detected were found exclusively after tabelecleucel infusion. Altogether, these results confirm that tracking TCRβ clones can be utilized as a novel assessment to detect post-infusion non-genetically modified allogenic cell therapies and future associations with clinical efficacy will be determined.

Temperature optimization of NiO hole transport layer prepared by atomic layer deposition

Atomic layer deposited (ALD) nickel oxide (NiO) thin film is frequently utilized as a hole transport layer (HTL) for perovskite solar cells (PSCs). Particularly nickel(II) 1-dimethylamino-2-methyl-2-butoxide (Ni(dmamb)2) precursor and ozone reactant are used for NiO film deposition. The substrate temperature effect on the stoichiometric composition for oxygen vacancies defects and electrical properties such as mobility is crucial, affecting further device performance. In the present study, NiO thin films are grown using the ALD method at a substrate temperature range between 180 to 250 °C on SiO2/Si substrates. Next, the effect of substrate temperature on the film composition, valence levels, nickel oxidation states, oxygen vacancies, and electrical properties was systematically examined, not to mention film growth, thickness, morphology, crystallinity, and optical properties. At 180 °C, the film growth rate was 0.017 nm/cycle, which was increased to 0.025 nm/cycle at 250 °C. All grown NiO films exhibited polycrystalline cubic crystal orientation, and the (200) plane simultaneously Ni3+ phase coexists with the Ni2+ phase. Furthermore, the electrical resistivity and mobility increased from 2.36 – 3.24 × 102 Ω.cm and 9.6–21.9 cm2V−1s−1 with substrate temperatures of 180 °C–230 °C. The prepared NiO films were optically transparent, >70% in the visible region, and the Ultraviolet photoelectron spectroscopy (UPS) study revealed that the variation in the valance band and conduction bands critically depended on the growth temperature. Thus, our findings reveal that the chemical and electrical characteristics of deposited NiO thin film are precisely influenced by substrate temperature; it will also offer considerable promise for developing NiO HTL concerning PSCs device improvement.

Mechanistic insights into the effects of alkali metal ion on ZSM-11 zeolite synthesis and its catalytic alkylation performance

Alkali metal cations showed significant effects on the zeolite synthesis process as well as its structure while the mechanism is still under debate. In this work, ZSM-11 zeolites were synthesized with the addition of four alkali metal cations (Li+, Na+, K+, Cs+). Except for different morphology and pore structure observed in the four samples, ZSM-11 synthesized with the presence of Li+ demonstrated low synthesis efficiency and weak acidic properties compared to those with the addition of Na+, K+, and Cs+ ions. Both DFT calculations and MD simulations were further performed to investigate the precursor reactions between silicates and aluminates as well as the polycondensation of two silicon-aluminum tetrahedral structural units. Except for the widely used factors including polarizable ability parameter (gi) and structural parameter (0W), two new parameters, i.e., polarizability (α0) and first hyperpolarizability (β0), were first employed as the descriptor to unravel the effects of alkali metal ion on ZSM-11 zeolite synthesis and properties. Obtained ZSM-11 samples exhibited the distinct catalytic performance for benzene alkylation with ethanol, which was attributed to the different structure and acidity properties. This work provides new insights into the deep understanding of the effects of alkali metal cations on zeolite synthesis in a closely mechanistic view.

Light and hydrogen peroxide dual-responsive DNA interstrand crosslink precursors with potent cytotoxicity

Arylboronic acid/esters and phenyl selenides-based quinone methide (QM) precursors were reported to induce DNA interstrand crosslink (ICL) formation upon reaction with the inherently high concentrations of H2O2 in cancer cells. However, some normal cells (such as macrophages) also contain high-levels of H2O2, which may interfere with precursors’ selectivity. In order to enhance the spatiotemporal specificity by the photolysis, we developed photo- and H2O2– dual-responsive DNA ICL precursors 1–3, bearing a photo-responsive coumarin moiety and a H2O2 inducible phenyl selenide group. Precursors 1–3 are efficiently activated by photoirradiation and H2O2 to generate reactive QMs crosslinking DNA. Moreover, the reactivity of precursors can be modulated by the introduction of aromatic substituents (OMe, F), and the electron donating group (OMe) displays a more pronounced promoting effect on DNA ICL formation. A subsequent piperidine heat stability study confirmed that the formed QMs primarily alkylate dAs, dGs and dCs in DNA. Furthermore, 1–3 inhibit lung cancer cell (H1299) growth by inducing DNA damage and producing toxic reactive oxygen species (ROS) upon photolysis of released coumarin. This study illustrates the potent cytotoxicity achieved by novel photo/H2O2 dual-responsive QM precursors 1–3, affording a novel strategy for the development of inducible DNA interstrand cross-linkers.

Chiral phosphoric acid-catalyzed reaction between C-alkynyl imine precursor and thiol: Access to highly enantioenriched alkynyl isoindolinones with N,S-ketal framework

An enantioselective reaction of cyclic C-alkynyl imine precursor with thiols catalyzed by (R)-H8-TRIP has been described. A broad range of alkynyl isoindolinones possessing a single chiral quaternary center and an N,S-ketal framework were synthesized in high yields (up to 99%) and excellent enantioselectivity (up to 99% ee). The practicality of the methodology was depicted by a gram scale synthesis and interesting synthetic transformation of products.

Discovery of Ervogastat (PF-06865571): A Potent and Selective Inhibitor of Diacylglycerol Acyltransferase 2 for the Treatment of Non-alcoholic Steatohepatitis.

Discovery efforts leading to the identification of ervogastat (PF-06865571), a systemically acting diacylglycerol acyltransferase (DGAT2) inhibitor that has advanced into clinical trials for the treatment of non-alcoholic steatohepatitis (NASH) with liver fibrosis, are described herein. Ervogastat is a first-in-class DGAT2 inhibitor that addressed potential development risks of the prototype liver-targeted DGAT2 inhibitor PF-06427878. Key design elements that culminated in the discovery of ervogastat are (1) replacement of the metabolically labile motif with a 3,5-disubstituted pyridine system, which addressed potential safety risks arising from a cytochrome P450-mediated O-dearylation of PF-06427878 to a reactive quinone metabolite precursor, and (2) modifications of the amide group to a 3-THF group, guided by metabolite identification studies coupled with property-based drug design.

Investigation of the sodium storage mechanism of iron fluoride hydrate cathodes using X-ray absorption spectroscopy and mossbauer spectroscopy

Elucidation of a reaction mechanism is the most critical aspect for designing electrodes for high-performance secondary batteries. Herein, we investigate the sodium insertion/extraction into an iron fluoride hydrate (FeF3⋅0.5H2O) electrode for sodium-ion batteries (SIBs). The electrode material is prepared by employing an ionic liquid 1-butyl-3-methylimidazolium-tetrafluoroborate, which serves as a reaction medium and precursor for F− ions. The crystal structure of FeF3⋅0.5H2O is observed as pyrochlore type with large open 3-D tunnels and a unit cell volume of 1129 Å3. The morphology of FeF3⋅0.5H2O is spherical shape with a mesoporous structure. The microstructure analysis reveals primary particle size of around 10 nm. The FeF3⋅0.5H2O cathode exhibits stable discharge capacities of 158, 210, and 284 mA h g−1 in three different potential ranges of 1.5–4.5, 1.2–4.5, and 1.0–4.5 V, respectively at 0.05 C rate. The specific capacities remained stable in over 50 cycles in all three potential ranges, while the rate capability was best in the potential range of 1.5–4.5 V. The electrochemical sodium storage mechanism is studied using X-ray absorption spectroscopy, indicating higher conversion at a more discharged state. Ex-situ Mössbauer spectroscopy strengthens the results for reversible reduction/oxidation of Fe. These results will be favorable to establish high-performance cathode materials with selective voltage window for SIBs.

Modelling the extraction process parameters of amorphous silica-rich rice husk ash using hybrid RSM−BPANN−MOGA optimization technique

This study was aimed to optimize process conditions for recovery of amorphous silica-rich rice husk ash (RHA) as a highly reactive precursor of silicon compounds for valorization of a non-conventional agricultural waste rice husk. The optimization was accomplished using a hybrid multi-objective genetic algorithm (MOGA) coupled with back-propagation artificial neural networks (BPANN) and response surface methodology (RSM). Herein, process conditions, namely leaching temperature (65–85 °C) & time (0.5–1.5 h) and calcination temperature (450–650 °C) & time (1−3 h) were considered as independent variables. The influence of process parameters on % crystallinity and volume % of silica in RHA were studied based on X-ray diffraction analysis and RHA recovery. In the hybrid RSM−BPANN−MOGA model, predicted data of BPANN were used as initial score and regression equations of RSM were used for development of fitness function. A set of optimal solutions were obtained as Pareto front and the final optimum design point was selected using TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) decision-making tool. The optimized process conditions were: leaching temperature: 75 °C, leaching time: 1 h, calcination temperature: 550 °C, and calcination time: 2 h. The optimized model was validated with observed results and found to be a well-fitted with absolute errors of 7.42%, 2.03%, and 4.26% for % crystallinity, RHA recovery, and vol% of silica, respectively. Further, a comparative study was performed between non-leached RHA and optimized RHA using several material characterization techniques. This study showed relative superiority of optimized treatment parameters with increased purity and decreased crystallinity and porous particle morphology.

(2,6-Dichloro-4-iodophenyl)bis(2,4,6-trichlorophenyl)methane as a precursor in efficient cross-coupling reactions for donor and acceptor functionalized triphenylmethyl radicals

To date, the functionalization of the tris(2,4,6-trichlorophenyl)methyl radical (TTM) is restricted to strong electron donating groups, whereas other substituents give only low or no reaction yields. Here, we present the synthesis of a mono-iodized derivative of the protonated TTM precursor (HTTM). It reacts readily in various types of cross-coupling reactions to give access to triphenylmethyl radicals functionalized with the respective electron donating or electron accepting groups. Iodized HTTM overcomes current limitations in accessibility and yield for TTM radicals functionalized with weaker electron donating groups and electron accepting groups, enabling the synthesis of virtually any desired TTM radical derivative. The performance of iodized HTTM is demonstrated by the synthesis of new stable radical compounds that are otherwise not or hardly accessible. Trimethoxyphenyl is introduced as a first nitrogen-free substituent of electron donating strength comparable to carbazole or diphenylamine. As electron accepting groups, we employ motifs such as benzophenone and pyrimidine and study the respective radicals for their optical properties.

Transparent and flexible vesicles/lamellae mixed matrix organic-bridged polysilsesquioxane coatings as water vapor barrier

Siloxane-based hybrid materials with lamellar nanostructure have great potential to be water vapor barrier layer for electronic devices and photovoltaic cells encapsulation. Improving water vapor barrier ability was still a big challenge. This research article proposed a facile one-pot methodology to prepare vesicles/lamellae mixed matrix organic-bridged polysilsesquioxane (BPSQ) composite coatings with excellent water vapor barrier performance. The composite coatings were fabricated from three thioether-ester-briged silsesquioxane by sol-gel method in the presence of phytic acid. Phytic acid not only acted as catalyst to catalyze the hydrolysis and condensation reactions of silsesquioxane precursors, but also formed vesicles in ethanol solution. Experimental evidence demonstrated that vesicles size mainly influenced the barrier property of composite coatings, and with bigger vesicles, the composite coating showed 10-fold enhancement in water vapor barrier ability compared to the corresponding BPSQ coating with only lamellar nanostructure. Moreover, the vesicles/lamellae composite coatings displayed outstanding transparency and flexibility which would meet the requirements of optical related moisture resistant application fields.

Design Principles of Colloidal Nanorod Heterostructures.

Anisotropic heterostructures of colloidal nanocrystals embed size-, shape-, and composition-dependent electronic structure within variable three-dimensional morphology, enabling intricate design of solution-processable materials with high performance and programmable functionality. The key to designing and synthesizing such complex materials lies in understanding the fundamental thermodynamic and kinetic factors that govern nanocrystal growth. In this review, nanorod heterostructures, the simplest of anisotropic nanocrystal heterostructures, are discussed with respect to their growth mechanisms. The effects of crystal structure, surface faceting/energies, lattice strain, ligand sterics, precursor reactivity, and reaction temperature on the growth of nanorod heterostructures through heteroepitaxy and cation exchange reactions are explored with currently known examples. Understanding the role of various thermodynamic and kinetic parameters enables the controlled synthesis of complex nanorod heterostructures that can exhibit unique tailored properties. Selected application prospects arising from such capabilities are then discussed.

Preparation and characterization of photo‐decomposable ester‐containing semi‐alicyclic polyimide alignment layers for potential applications in in‐plane switching thin‐film transistor liquid crystal display devices

AbstractPoly(amic acid)s (PAAs) alignment agents have been prepared from the alicyclic dianhydrides, including 1,2,3,4‐cyclobutanetetracarboxylic dianhydride (CBDA, I), 1,3‐dimethyl‐1,2,3,4‐cyclobutanetetracarboxylic dianhydride (DMCBDA, II), and ester‐linked aromatic diamines, including 4‐aminophenyl‐4′‐aminobenzoate (APAB, a) and bis(4‐aminophenyl)terephthalate (BPTP, b), respectively. The derived PAAs, including PAA‐Ia (CBDA‐APAB), PAA‐Ib (CBDA‐BPTP), and PAA‐IIa (DMCBDA‐APAB) exhibited the preferable molecular weights, while the PAA‐IIb (DMCBDA‐BPTP) showed the low one due to the low polymerization reactivity both for the DMCBDA dianhydride and the BPTP diamine. All the PAA solutions except PAA‐IIb were adopted as the alignment components to fabricate liquid crystal (LC) minicells with a mode of in‐plane switching (IPS). The polyimides (PI) alignment layers derived from the thermal dehydration reaction of the PAA precursors at 230°C for 30 min showed good alignments effects to the LC molecules, which exhibited the pretilt angles (θp) from 0.09 to 0.15° after being exposed by the linear polarized ultraviolet light sources with the wavelength of 254 nm. In addition, the PI alignment layers afforded good optoelectronic features to the minicells, including the voltage holding ratio values over 97% at room temperature, and the residual direct circuit voltages lower than 1.0 V. The anchoring energy results indicated that the PI‐IIa (DMCBDA‐APAB) alignment layer showed the highest interaction with the LC molecules, and thus exhibited the highest threshold voltage (Vth) in the voltage‐transmittance (V‐T) measurements for the minicells.

Effect of PVP surfactant on the synthesis of CuO nanoribbons by the chemical reduction method

This work developed a simple and time-dependent method to synthesize CuO nanoribbons. For this, the concentration of the precursor salt (CuCl2), surfactant (PVP), and reaction times were varied, keeping constant the reducing agent (NaBH4). SEM, TEM, XRD, and EDS characterized CuO ribbon-like particles' morphology, chemical composition, and structure. SEM studies confirmed that CuO nanoribbons appear after three weeks of reaction aging by mixing CuCl2 (17 mM), NaBH4 (26 mM), and PVP (1.6 mM). The nanoribbons have a relatively low aspect ratio of 2 to 3 µm long and around 60 nm wide. XRD and TEM confirmed the monoclinic structure of the CuO nanoribbons. SEM micrographs also indicated that as the salt concentration decreases to 10 mM, the size of the products decreases, and nanosheet-like nanostructures with lengths less than 1 μm and thicknesses of 100 nm are formed. PVP was found to have a great influence on the morphology of the nanostructures. For example, low amounts of PVP increase particle oxidation, easily driving the formation of CuO nanoribbons. At the same time, larger amounts stabilize the formation of Cu2O octahedral particles.

Molecular Basis for the Simultaneous Enhancement of the Aroma-Generating Capacity and Bioactivity of Maillard Reaction Precursors through Mechanochemistry.

Ball milling at ambient temperatures can accelerate the formation and accumulation of early-stage Maillard reaction intermediates considered important precursors of aromas and antioxidants. In this study, using chemical and biological assays, we explored the potential of sequential milling and heating to enhance the antioxidant and aroma-generating capacity of Maillard model systems. Milling (30 Hz/30 min) followed by dry heating (90 °C/30 min) of glycine or lysine with glucose significantly increased not only the intensity of their aroma-active compounds as analyzed by headspace-gas chromatography/mass spectrometry (HS-GC/MS) but also their free radical scavenging capacity as assessed by 2,2'-azino-bis-(3-ethylbenzothiazoneline-6-sulfonic acid) (ABTS) and oxygen radical absorbance capacity (ORAC) assays. This was attributed to the increased formation of redox-active endiol moieties and precursors of N,N-dialkyl-pyrazinium radical cation in the lysine system assessed by electrospray ionization-quadrupole time-of-flight/tandem mass spectrometry (ESI-QqTOF/MS/MS) analysis. The test samples also inhibited NO generation and cellular oxidative stress in RAW 264.7 murine macrophage cells, indicating size reduction induced by milling promoted paracellular absorption.