Phenyl Ethyl Research Articles

Tailoring Dielectric Properties and Dimensional Stability of Poly(Phenylene Ether) Using Bismaleimide Crosslinkers for High-Frequency PCB Applications.

With the increasing demand for high-performance printed circuit boards (PCBs) in the 6G communication era, dielectric substrate materials must exhibit a low dielectric constant (Dk), low dielectric loss (Df), and high dimensional stability. In this study, a series of bismaleimide-incorporated poly(phenylene ether) resins (PPE-BMI) with varying bismaleimide (BMI) crosslinker contents is developed, exhibiting significantly enhanced dielectric properties and dimensional stability, owing to the restricted polymer chain mobility and increased crosslinking density. Dielectric property measurements reveal that the PPE-BMI resins exhibit low Dk and Df values at frequencies above 100GHz, while maintaining an excellent dielectric performance even after an 85 °C/85% relative humidity reliability test. A significant reduction in the coefficient of thermal expansion is observed with an increase in the BMI content. Molecular dynamics simulations are employed to clarify the role of BMI crosslinkers in reducing the free volume, enhancing the crosslinking in the PPE (poly(phenylene ether)) matrix, and influencing the thermophysical properties of PPE-BMI. The infiltration of PPE-BMI into glass fabrics and liquid crystal fabrics highlights their potential for practical use in advanced PCB applications operating at high frequencies.

The Potential of Co-Fermentation with Pichia kluyveri and Saccharomyces cerevisiae for the Production of Low-Alcohol Craft Beer

The potential health impacts of moderate alcohol consumption have long been debated. The COVID-19 pandemic has heightened public awareness of health concerns, creating a clear market opportunity for low-alcohol craft beer development. This study investigated the possibility of low-alcohol craft beer by co-fermentation with different ratios of Pichia kluyveri (P. kluyveri) and Saccharomyces cerevisiae (SC) according to the established quality indexes. Specifically, this study was conducted to identify the low-alcohol craft beer quality by fermentation kinetics, growth kinetics, apparent attenuation (AA), real attenuation (RA), residual sugar content, alcohol by volume (ABV), and volatile organic compounds. This study demonstrated that the co-fermentation of SC and P. kluyveri in a 1:10 ratio produced an ABV of 2.98% (v/v). In addition, high concentrations of isoamyl acetate and phenyl ethyl acetate revealed banana, rose, apple, and honey flavors, respectively. Overall, this study revealed that the fermentation of P. kluyveri and SC by co-fermentation and the fermentation process by adjusting the yeast composition developed a craft beer with low alcohol content and rich aroma while establishing the quality indicators.

Dual Au/Ag Catalyzed Regiospecific Intramolecular Hydroacyloxylation and Hydroalkoxylation of Unactivated Geminal-Substituted Olefins.

A mild, regiospecific Gold-Silver bimetallic catalytic system has been devised for the intramolecular hydroacyloxylation and hydroetherification of alkenoic acids and alcohols. This method exhibits precise specificity for the geminal substituted olefinic center and facilitates the synthesis of substituted phthalide and hydroisocoumarin derivatives. This method has been effectively applied for late-state functionalization to produce bioactive natural products such as rumphellaone A, mycophenolate, and (-)-ambrox. The successful gram-scale synthesis of the anticonvulsant, hypnotic drug (±)-ethyl phenyl butyro lactone (EPBL), (±)-Boivinianin A and the ability to synthesize challenging spiro and bicyclic lactone underscores the synthetic potential of this methodology. Mechanistic insights into gold-silver catalyzed lactonization of olefins have also been discussed.

Influence of Terroir on the Grain Composition, and Volatile Profile of Irish Grain (Wheat) New Make Spirit

Terroir refers to the combination of environmental factors, such as climate, soil, and agricultural practices, that shape the characteristics of a crop, contributing to the unique qualities of the final product. The concept has been traditionally linked to wine, but some recent findings suggest that it also holds importance for distilled spirits. The expanding Irish distilling sector is shifting towards local raw materials such as wheat and rye, driven by regulatory changes, economic benefits, and consumer demand for sustainable local products. This research examines the effects of wheat variety, geographical location, and harvest year on grain composition and volatile composition of the new make spirit. For this study, twenty lab-scale wheat whiskey samples were produced from five different wheat varieties grown at two different locations in Ireland over two consecutive years. The wheat samples were analysed for grain composition and the volatile profiling of new make spirit samples by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry (GC-MS). A total of fifty-one volatile compounds were detected, with ethanol, ethyl acetate, phenyl ethyl alcohol, and 3-methyl-1-butanol being predominant. Principal component analysis revealed that both the harvest year and geographical location moderately influenced the volatile compound distribution of the new make spirit, which is explained by a 43.25% variance. ANOVA analysis revealed that grain composition was significantly influenced by harvest year, location, and wheat variety. The 2020 samples showed higher protein and β-glucan content, whereas samples from the location Tipperary had higher starch content. This study indicates that terroir—specifically seasons (year) and geography (location)—affects the characteristics of wheat-based Irish whiskey, highlighting opportunities for distillers to differentiate their products by leveraging local environmental factors.

The Effect of Platelet-Rich Plasma and Hyaluronic Acid Nasal Injections in the Treatment of Traumatic Olfactory Dysfunction.

Objective: Platelet-rich plasma (PRP) has been injected into the olfactory cleft to treat olfactory dysfunction related to coronavirus disease 2019. In this study, we aimed to evaluate the effect of PRP combined with hyaluronic acid (HA) nasal injection in the treatment of traumatic olfactory dysfunction. Methods: Patients who had lost olfactory function after experiencing head trauma and were willing to receive PRP and HA nasal injections for treatment were enrolled. Before nasal injection, 10 cc of blood was drawn from the patients. The drawn blood was injected into a centrifuge tube for processing, and finally, 5 cc of the PRP mixed with HA was drawn out using an empty syringe. The PRP mixed with HA was injected into the upper part of the middle nasal septum and the medial side of the middle turbinate of the patient's nasal cavity under a nasal endoscope. The olfactory function of each patient was evaluated by the phenyl ethyl alcohol (PEA) odor detection threshold test before and at both 1 and 3 months after nasal injection and the traditional Chinese version of the University of Pennsylvania Smell Identification Test at 3 months after nasal injection. Results: A total of 28 patients received PRP and HA nasal injections between August and December of 2023 and came back for evaluation of the effect. In all, 20 (71.4%) patients felt their olfactory function improved 1 month after injection, and 24 of 28 (85.7%) patients reported their olfactory function improved at 3 months after injection. The bilateral or unilateral PEA threshold decreased in 22 (78.6%) patients 1 month after injection, and decreased in 15 (53.6%) patients 3 months after injection. Conclusions: Our results show that PRP and HA nasal injections were associated with favored patient-reported outcomes and improved the olfactory threshold in the treatment of traumatic olfactory dysfunction.

Discovering the DPPH Free Radical Scavenging Activity of Azine Derivatives Bearing Ethyl Phenyl Ketone Moiety

Discovering the DPPH Free Radical Scavenging Activity of Azine Derivatives Bearing Ethyl Phenyl Ketone Moiety

The molecular effects of ozone on human hemoglobin oligomerisation pre- and post-COVID-19 infection accompanied by favoured antioxidant roles of cinnamaldehyde and phenyl ethyl alcohol

Many studies have shown that oxidative stress plays a pivotal role in pathogenesis of coronavirus disease 2019 (COVID-19). In the present work, a case-study was conducted by comparing human hemoglobin (Hb) oligomerization upon autohemotherapy before and after COVID-19 infection. Structural changes of Hb exposed to different concentrations of ozone (40, 60, and 80 μg/ml) in whole blood, before COVID-19 infection, was compared to Hb exposed to the highest concentration of ozone (80 μg/ml) in whole blood, in the presence of two antioxidants, cinnamaldehyde (Cin) and phenyl ethyl alcohol (PEA), after COVID-19 infection. The structural analyses in this study was performed using various techniques, including DPPH radical scavenging assay, intrinsic fluorescence spectroscopy, circular dichroism (CD) spectroscopy, UV–VIS absorption spectroscopy, SDS-PAGE, dynamic light scattering (DLS), and molecular docking studies. The results showed that Hb oligomerization by ozone increased significantly after COVID-19 infection. In addition, at an ozone concentration of 80 μg/ml, the affinity of heme groups for globin chains and to oxygen molecules were shown to increase, whereas the stability of Hb decreased. In contrary, the addition of Cin and PEA prevented the adverse effects of ozone with PEA showing more efficacy in maintaining the native structure of Hb. Taken together, these results provided insights into the adverse effects of COVID-19 infection on Hb oligomerization and highlighted the importance of an individual's antioxidant capacity in protecting Hb from ozone, especially high ozone concentrations in autohemotherapy, and further emphasised the importance of personalising the concentration of ozone for patient administration, in order to provide a safe and effective autohemotherapy treatment.

Elucidating phonon dephasing mechanisms in layered perovskites with coherent Raman spectroscopies.

Organic-inorganic hybrid perovskite quantum wells exhibit electronic structures with properties intermediate between those of inorganic semiconductors and molecular crystals. In these systems, periodic layers of organic spacer molecules occupy the interstitial spaces between perovskite sheets, thereby confining electronic excitations to two dimensions. Here, we investigate spectroscopic line broadening mechanisms for phonons coupled to excitons in lead-iodide layered perovskites with phenyl ethyl ammonium (PEA) and azobenzene ethyl ammonium (AzoEA) spacer cations. Using a modified Elliot line shape analysis for the absorbance and photoluminescence spectra, polaron binding energies of 11.2 and 17.5meV are calculated for (PEA)2PbI4 and (AzoEA)2PbI4, respectively. To determine whether the polaron stabilization processes influence the dephasing mechanisms of coupled phonons, five-pulse coherent Raman spectroscopies are applied to the two systems under electronically resonant conditions. The prominence of inhomogeneous line broadening mechanisms detected in (AzoEA)2PbI4 suggests that thermal fluctuations involving the deformable organic phase broaden the distributions of phonon frequencies within the quantum wells. In addition, our data indicate that polaron stabilization primarily involves photoinduced reorganization of the organic phases for both systems, whereas the impulsively excited phonons represent less than 10% of the total polaron binding energy. The signal generation mechanisms associated with our fifth-order coherent Raman experiments are explored with a perturbative model in which cumulant expansions are used to account for time-coincident vibrational dephasing and polaron stabilization processes.

Optimizing latex-modified concrete for enhanced workability and durability in pavement construction

High temperatures during summer pavement construction can lead to rapid drying, adversely affecting the workability and homogeneity of concrete mixtures, often resulting in quality issues such as cracks and surface defects. This study aims to overcome these challenges by introducing latex modified concrete (LMC) as a solution for enhancing the quality of summer pavement construction. Latex, known for its excellent flexibility and physical properties, is employed to improve the workability and strength of concrete. The study focuses on enhancing the workability and performance of latex in bridge construction within LMC during the summer. The effects of nonionic emulsifier type, alkyl ethylene oxide (AEO) and alkyl phenyl ethylene oxide (APEO), were investigated. In latex, the AEOs with alkyl chains containing 9–13 carbons and 20–40 ethylene oxide units exhibited remarkable workability in LMC. To improve workability even more, the addition of 0.5 wt% superplasticizer per unit of cement was found to be effective. This research contributes to the field by demonstrating the efficacy of nonionic emulsifiers and superplasticizers in latex in enhancing summer workability and their effects on the compressive strength of concrete.

Novel dry facial mask based on emulsion electrospinning

Facial masks have become omnipresent daily, providing the skin with sufficient moisture and activated nutrients. However, conventional wet facial masks use large amounts of preservatives and antimicrobials, which are not friendly to human health and ecological environment. Herein, emulsion electrospinning was innovatively used to prepare eco-friendly resveratrol (RES) and phenyl ethyl resorcinol (PR)-loaded polyvinyl alcohol (PVA) dry nanofiber facial mask, avoiding the usage of preservatives and antimicrobials. The SEM results showed that the dry PVA/RES/PR facial masks have a mean diameter of about 205 nm. When used, the active substances (RES and PR) inside the nanofiber facial mask are released by moisture spray, activating the active substances released in response to water, providing an in-situ moisturizing effect (improved 13 %), antioxidant performance (free radical scavenging rate, 86 %), and antibacterial performance (antimicrobial efficiency of 99.98 % and 99.99 % against E. coli and S. aureus). Moreover, the dry PVA/RES/PR facial mask can be sealed with biodegradable paper packaging instead of plastic packaging. The novel environmental dry facial mask prepared with emulsion electrospinning is a suitable material to study and apply in cosmetics.

Aromatic copolyesters with tunable dielectric and thermal properties enabled by aryl building blocks

Polymer dielectric materials in high-frequency communication applications needs to meet strict requirements, and the future development trend is high performance and environmental friendly materials. Herein, we propose a design strategy for simultaneously adjusting multiple performances by building blocks (naphthyl, diphenyl ether, and phenyl). The synthesized copolyester containing phenylene ether structures exhibits good comprehensive properties, including high thermal stability (the temperature at 5 wt% weight loss, 475–495 °C) and inherent flame retardancy (limiting oxygen index 37.8 %∼40.1 %, UL-94 V-0 level), low water absorption (0.16 %∼0.46 %), low dielectric constant (3.04–3.31 @10 GHz) and low dielectric loss (0.0020–0.0028 @10 GHz). The crankshaft naphthyl and bent diphenyl ether structures together change the free volume or spacing of polymer chains, thereby effectively affecting the density or motility of the polarizable groups. These aromatic structures also possess high charring-ability, thus enabling the polymers with the inherent high flame retardancy. Since only carbon, hydrogen, and oxygen elements are introduced into the copolyesters, it supplies a solving approach to eliminate the potential chemical concern arising from introducing heteroatoms such as halogen or phosphorus into polymers.

Typ‐I‐Photoinitiator auf der Basis nachhaltiger Kohlenstoffpunkte

AbstractNachhaltige Kohlenstoffpunkte, die an der Oberfläche Oximestergruppen enthalten, welche einer homolytischen Bindungsspaltung folgen, zeigen ein Potential als Photoinitiatoren für die traditionelle freie radikalische Photopolymerisation. Die Kohlenstoffpunkte wurden nach einem solvothermalen Verfahren aus nachhaltigem Furfural, welches über Lignocellulose erhältlich ist, hergestellt. Aldehydgruppen der Oberfläche reagierten mit Hydroxylamin zu dem entsprechendem Oxim, während die Reaktion mit Benzoylchlorid zu einem bio‐basierten Typ I Photoinitiator (CD‐PI) führte, welcher nachhaltige Kohlenstoffpunkte enthält. Die Fähigkeit zur Photoinitiierung wurde unter UV‐Bestrahlung bei 365 nm mit dem traditionellen Photoinitiator (PI) Ethyl (2,4,6‐trimethyl benzoyl) phenyl phosphinat (TPO‐L) mittels Echtteit FTIR Spektroskopie verglichen. Die auf einem Gemisch von Urethandimethacrylat (UDMA) und Tripropylenglykoldiacrylat (TPGDA) basierte Photopolymerzusammensetzung führte unter Verwendung von CD‐PI oder TPO‐L zu einem ähnlichen Endumsatz von etwa 70 %. Dennoch erschien das vernetzte Material im Fall der Zusammensetzungen, die mit CD‐PI verarbeitet wurden, homogen, während jene, die mit TPO‐L hergestellt wurden, heterogen waren, was durch die beiden Glasübergangstemperaturen gezeigt wurde. Außerdem war die Migrationsgeschwindigkeit von CD‐PI in den gehärteten Proben geringer im Vergleich zu jenen Proben für die TPO‐L als PI eingesetzt wurde.

Type I Photoinitiator Based on Sustainable Carbon Dots.

Sustainable carbon dots comprising surficial oxime ester groups following homolytic bond cleavage exhibit potential as photoinitiators for traditional free radical photopolymerization. Carbon dots were made following a solvothermal procedure from sustainable furfural available from lignocellulose. Surficial aldehyde moieties reacted with hydroxylamine to the respective oxime while reaction with benzoyl chloride resulted in a biobased Type I photoinitiator comprising sustainable carbon dot (CD-PI). Photoinitiating ability was compared with the traditional photoinitiator (PI) ethyl (2,4,6-trimethyl benzoyl) phenyl phosphinate (TPO-L) by real-time FTIR with UV exposure at 365 nm. Photopolymer composition based on a mixture of urethane dimethacrylate (UDMA) and tripropylene glycol diacrylate (TPGDA) resulted in a similar final conversion of about 70 % using either CD-PI or TPO-L. Nevertheless, it appeared homogeneous in the case of compositions processed with CD-PI, while those made with TPO-L were heterogeneous as shown by two glass transition temperatures. Moreover, the migration rate of CD-PI in the cured samples was lower in comparison with those samples using TPO-L as PI.

Combination of NIR and UV‐LEDs enables physical and chemical drying of aqueous coating dispersions as new green technology

AbstractHeptamethine based cyanines, namely 1,3,‐trimethyl‐2‐(2‐2[2‐phenylsulfanyl‐3‐[2‐(1,3,3‐trimethyl‐1,3,3‐trithyl‐1,3‐dihydro‐indol‐2‐ylidene)‐ethylidene]cyclohex‐1‐enyl]vinyl)‐3H‐indolium chloride (S1) and 2‐[2‐(2‐chloro‐[2‐[1,1‐dimethyl‐7‐sulfo‐3‐(4‐sulfobutyl)‐1,3‐dihydro‐benzo[e]indol‐2‐ylidene]‐ethylidene]cyclopent‐1‐enyl]vinyl]‐1,1‐dimethyl‐7‐sulfo‐3‐(4‐sulfobutyl)‐1Hbenzo[e]indolium hydroxide, inner salt, triethylammonium salt (S2), efficiently result in physical drying of an aqueous dispersion comprising a polyurethane binder. S2 possesses a water solubility of 40 g/L. A high‐intensity near‐infrared‐LED emitting at 820 nm with an intensity of 1 W/cm2 served as light source. The cyanine converted the light absorbed into heat by internal conversion needing less drying time compared to conventional drying. Water content after film formation showed less then 1%. In the second step, ultraviolet (UV) exposure with a LED emitting at 395 nm resulted in formation of semi‐interpenetrating polymer networks by crosslinking of the multifunctional (meth)acrylate operating as reactive diluent. Ethyl phenyl(2,4,6‐trimethylbenzoyl)phosphinate‐L served as effective UV‐photoinitiator. Furthermore, the UV‐exposure together with Norrish Type I and Type II photoinitator systems results in a very efficient bleaching of the green physical dried film. This contribution shows for the first time a new photonic hybrid technique describing successful replacement of an oven‐based process by a photonic based step that generates heat needed for drying.

Confinement of Sustainable Carbon Dots Results in Long Afterglow Emitters and Photocatalyst for Radical Photopolymerization.

Sustainable carbon dots based on cellulose, particularly carboxymethyl cellulose carbon dots (CMCCDs), were confined in an inorganic network resulting in CMCCDs@SiO2. This resulted in a material exhibiting long afterglow covering a time frame of several seconds also under air. Temperature-dependent emission spectra gave information on thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) while photocurrent experiments provided a deeper understanding of charge availability in the dark period, and therefore, its availability on the photocatalyst surface. The photo-ATRP initiator, ethyl α-bromophenylacetate (EBPA), quenched the emission from the millisecond to the nanosecond time frame indicating participation of the triplet state in photoinduced electron transfer (PET). Both free radical and controlled radical polymerization based on photo-ATRP protocol worked successfully. Metal-free photo-ATRP resulted in chain extendable macroinitiators based on a reductive mechanism with either MMA or in combination with styrene. Addition of 9 ppm Cu2+ resulted in Mw/Mn of 1.4 while an increase to 72 ppm improved uniformity of the polymers; that is Mw/Mn=1.03. Complementary experiments with kerria laca carbon dots confined materials, namely KCDs@SiO2, provided similar results. Deposition of Cu2+ (9 ppm) on the photocatalyst surface explains better uniformity of the polymers formed in the ATRP protocol.

Der Einschluss von nachhaltigen Kohlenstoffpunkten führt zu langnachleuchtenden Emittern und zu Photokatalysatoren für die radikalische Photopolymerisation

AbstractNachhaltige Kohlenstoffpunkte auf der Basis von Cellulose, insbesondere Carboxymethylcellulose basierende Kohlenstoffpunkte (CMCCDs), wurden in ein anorganisches Netzwerk eingeschlossen, was zur Bildung von CMCCDs@SiO2 führte. Das resultierende Material zeigte ein lange anhaltendes Nachleuchten, welches ein Zeitfenster von mehreren Sekunden auch in Gegenwart von Luft umfasste. Temperaturabhängige Emissionsspektren gaben eine Information über die thermisch aktivierte verzögerte Fluoreszenz (TADF) und eine Phosphoreszenz bei Raumtemperatur (RTP), während Experimente zur photoinduzierten Generierung von Ladungsträgern zu einem tieferen Verständnis der Verfügbarkeit von Ladungen in der Dunkelphase führten und daher zu ihrer Verfügbarkeit an der Katalysatoroberfläche. Der photo‐ATRP Initiator α‐Bromphenylethylacetat (EBPA) bewirkte eine Löschung der Emission, was zu einer Verkürzung des Zeitfensters für die Emission vom Millisekundenbereich in den Nanosekundenbereich führte und auf eine Beteiligung des Triplettzustandes an dem photoinduzierten Elektronentransfer (PET) hinweist. Sowohl die freie radikalische Polymerisation als auch die kontrollierte auf einem photo‐ATRP Protokoll basierende radikalische Polymerisation von MMA oder in Kombination mit Styren funktionierten erfolgreich. Die metallfreie photo‐ATRP führte basierend auf einem reduktiven Mechanismus zu einem kettenverlängerbaren Makroinitiator. Die Zugabe von 9 ppm Cu2+ führte zu einem Verhältnis Mw/Mn von 1.4 obwohl eine Erhöhung auf 72 ppm die Einheitlichkeit der Polymere verbesserte, was einem Mw/Mn=1.03 entspricht. Ergänzende Experimente mit in kerria laca eingeschlossenen Kohlenstoffpunkten, insbesondere KCDs@SiO2, führten zu ähnlichen Ergebnissen. Die Abscheidung von Cu2+ (9 ppm) an der Photokatalysatoroberfläche erklärt die bessere Dispersität der Polymere, welche mittels der ATRP gebildet wurden.

Impact of lactic acid bacteria starter inoculation on the Physico-chemical, microbiological, volatiles and sensory properties of natural black Gemlik (Olea europaea L., cv.) table olives

Traditionally, the fermentation of Gemlik table olives takes place spontaneously by the endogenous microbiota in Turkey, but the uncontrolled process during fermentation can result in the formation of off-flavours and a low sensory quality of the final product. In this research, the effects of inoculating naturally black Gemlik olives with Lactiplantibacillus pentosus and Lactiplantibacillus plantarum starter cultures on lactic fermentation development, volatile compounds, and sensory properties were investigated. Changes in spontaneous and culture inoculated olives were monitored during fermentation. Compared to spontaneous fermentation, rapid acidification, and sugar depletion were achieved with the use of starter cultures. Extra lactic acid bacteria and total yeast growth were detected in the inoculated trials during fermentation compared to the control trial. Volatile compounds in olives were extracted by the Purge and Trap method. 46 volatile compounds from 10 chemical groups have been identified in olives. In all three trials, volatile acids were the group of volatile compounds found in the top amount in olives, higher alcohols, phenols, aldehydes/ketones, and terpenes followed the volatile acids. Phenyl ethyl alcohol, α-farnesen, (Z)-3-hexene-1-ol and 2-hexanol, which give pleasant flavors, were determined to be in more quantity in olives with inoculated starter cultures. This study reveals that the use of starter culture provides advantages in the production of Gemlik variety table olives, positively affects aroma development, and improves sensory properties.

Impact of Storage Temperature on Green Tea Quality: Insights from Sensory Analysis and Chemical Composition

This study investigated the impact of storage temperatures (−20 °C, room temperature, and 40 °C) on the sensory evaluation, metabolites, and volatile compounds of green tea stored for 12 months. The sensory evaluation revealed that tea samples stored at −20 °C retained their emerald green colour, tender aroma, and refreshing taste. Green tea biochemical constituents, including water extracts and total free amino acids, were measured by Chinese National Standard Methods (GB/T 8305-2013 and GB/T 8314-2013). Tea polyphenols and flavonoids were determined using spectrophotometric methods, while phytochemicals were detected using validated HPLC, and volatile compounds were detected using validated gas chromatography coupled with triple quadrupole mass spectrometry. The analysis showed that tea polyphenols were highest at −20 °C, and flavonoids were significantly reduced at higher temperatures. A similar trend was observed for amino acids, soluble sugar content, and water extracts. Tea catechins, including (-)-epigallocatechin-3-gallate (EGCG) and (-)-gallocatechin gallate (GCG), were highest at −20 °C, showing their susceptibility to temperature. A volatile compound analysis revealed distinct profiles with variations in the abundance of compounds, such as di-methyl sulfide, phenyl ethyl alcohol, indole, and benzaldehyde. This study identifies temperature-sensitive compounds, providing insights into the mechanisms underlying tea quality deterioration during storage.

Elucidating the Crystallization‐Caused Phosphorescence Quenching Mechanism to Achieve Efficient Photoactivated Persistent Luminescence for High‐Quality Light Printing

AbstractThe development of polymer‐based luminescent materials with efficient photoactivated ultralong organic phosphorescence (UOP) is of great importance but very challenging. Herein, a new class of organic phosphorescent luminogens is constructed by attaching phenyl rings and/or ethyl benzoates to the nitrogen atoms of a planar aromatic heterocycle pyrrolodiindole (PDI). The compounds show a significant elevation in phosphorescence emission capability after incorporating the ester group(s). However, they cannot produce room‐temperature phosphorescence in the crystalline state. These observations are identified to be associated with the formation of dimers and excimers and the motions of substituents within the molecules. In this context, the PDI derivatives are doped into epoxy polymers with compact and permanent 3D covalent networks. The resulting polymer films show reversible photoactivated UOP under ambient conditions, with quantum yields and lifetimes of up to 24.4% and 2.03 s, respectively, thereby enabling high‐quality and erasable light printing and multi‐level anti‐counterfeiting applications. In addition, they also exhibit excellent water and chemical resistance. This work is conducive to understanding the generation and decay mechanisms of the triplet excitons of organic luminophores with planar aromatic heterocycles in the crystalline state and provides a direction for the development of high‐performance photoactivated UOP materials.

Saccharomyces cerevisiae Bioactive Metabolites: Characterization and Biological Activities

AbstractThis study aimed to extract bioactive secondary metabolites, determine volatile organic compounds, and polyphenols using GC/MS and LC/MS, and assess their total phenolic content, antimicrobial, antioxidant, and cytotoxic properties. The chemical analysis of S. cerevisiae NRLL Y‐12633 ethyl acetate extract revealed eight volatile organic components, whereas the main component was phenyl ethyl alcohol (77.39 %). On the other hand, nineteen volatile organic compounds were identified in the ethyl acetate extract of S. cerevisiae NRRL Y‐1089, whereas the most critical component was 2, 3‐butanediol (60.74 %). The most abundant phenolic acids were syringic acid (25476.46 ng/mL), and cinnamic acid (5163.76 ng/mL) in the ethyl acetate extracts of S. cerevisiae NRLL Y‐12633 and S. cerevisiae NRRL Y‐1089 respectively. Flavonoid, naringenin, was also found in the ethyl acetate extract of S. cerevisiae NRLL Y‐12633, whereas daidzein and rutin were detected in the ethyl acetate extract of S. cerevisiae NRRL Y‐1089. The total phenolic content of S. cerevisiae NRRL Y‐12633 ethyl acetate extract was found to be greater than that of S. cerevisiae NRRL Y‐1089 ethyl acetate extract. Data revealed that S. cerevisiae ethyl acetate extracts displayed antioxidant and antimicrobial activity, whereas only the ethyl acetate extract of S. cerevisiae NRRL Y‐1089 showed anticancer activity.