Establishment of high-performance liquid chromatography-photodiode array method for 43 weight loss agents and effect of basic environment on bisacodyl degradation.

RATIONALE: The demand for weight loss products is increasing as slimness emerges as the new aesthetic standard and people's desire to achieve it increases. In addition, the distribution and sale of products containing illegal ingredients, pharmaceuticals, and chemicals for which safety is not guaranteed and that cannot be used as foods or dietary supplements are increasing. Thus, the development of an analytical method that could monitor these illegal products is required. METHODS: A high-performance liquid chromatography-photodiode array method capable of rapid and reliable qualitative and quantitative analyses of 43 weight loss agents was established and validated. RESULTS: The process involved dividing analytes into three groups for rapid analysis; when bisacodyl was mixed with chlorocyclopentylsibutramine, it decomposed into its metabolites: monoacetyl bisacodyl and bis-(p-hydroxypheny)-pyridyl-2-methane. This decomposition was due to NaOH that was used to prepare the chlorocyclopentylsibutramine standard solution. Bisacodyl did not degrade when mixed with neutralized chlorocyclopentylsibutramine, whereas when NaOH was added, it rapidly degraded. We identified the bisacodyl degradation products using liquid chromatography-quadrupole-Orbitrap/mass spectrometry. MS2 spectra with proposed structures of fragment peaks were also obtained. CONCLUSIONS: The developed method could be used to regulate slimming products that threaten public health, and knowledge of bisacodyl degradation will be used as the basis for developing an analytic method.

Simultaneous determination of 11 nootropic substances potentially adulterated in dietary supplements for improving brain function using ultra-performance liquid chromatography and liquid chromatography-quadrupole-time-of-flight mass spectrometry.

Recently, the demand for improved brain function and concentration has increased in the dietary supplement market. However, to artificially enhance their pharmacological efficacy, dietary supplements may be illegally adulterated with unauthorised substances. Therefore, we developed a rapid and accurate method to simultaneously determine 11 nootropic substances using an ultra-high-performance liquid chromatography (UPLC) system equipped with a photodiode array (PDA) detector. In addition, sample preparation procedures were semi-optimised for various types of matrices, including solid (hard capsule, tablet, powder, and pill) and liquid (oil and extract) samples. The method was validated to determine the limit of detection (LOD), limit of quantification (LOQ), method detection limit (MDL), method quantitation limit (MQL), specificity, linearity, precision, accuracy, recovery, stability, and matrix effects. The validation results satisfied international validation guideline requirements. To test the applicability of the method, 55 real samples advertised as effective brain health, memory, and cognition supplements were analysed. Among the real samples, vinpocetine (2.483 and 7.296 µg/g), and kavain (69-44.056 µg/g) were detected. In addition, the detected compounds were confirmed by comparing their fragmentation patterns with those of the reference standards using liquid chromatography-quadrupole-time-of-flight mass spectrometry (LC-QTOF/MS). In conclusion, the UPLC-PDA method not only rapidly and accurately quantifies illegal nootropics but also enables the pre-emptive investigation and identification of 11 nootropic substances in illegal dietary supplements to protect public health.

Effect of Electron-Withdrawing Chlorine Substituent on Morphological and Photovoltaic Properties of All Chlorinated D-A-Type Quinoxaline-Based Polymers.

The choice of the chlorine (Cl) atom as an electron-withdrawing substituent in conjugated polymers leads to a higher potential in the commercialization of polymer solar cells than its fluorine counterpart because of the versatility and cost-effectiveness of the chlorination process. In addition, the population and location of Cl substituents can significantly influence the photovoltaic characteristics of polymers. In this study, three chlorinated quinoxaline-based polymers were invented to examine the numerical and positioning effects of the Cl atom on their photovoltaic characteristics. The number of Cl substituents in the reference polymer, PBCl-Qx, was adjusted to three: two Cl atoms in the benzodithiophene-type D unit and one Cl atom in the quinoxaline-type A unit. Subsequently, two more Cl atoms were selectively introduced at the 4- and 5-positions of the alkylated thiophene moieties at the 2,3-positions of the quinoxaline moiety in PBCl-Qx to obtain the additional polymers PBCl-Qx4Cl and PBCl-Qx5Cl, respectively. The conventional PBCl-Qx4Cl device exhibited a better power conversion efficiency (PCE) of 12.95% as compared to those of PBCl-Qx (12.44%) and PBCl-Qx5Cl (11.82%) devices. The highest PCE of the device with PBCl-Qx4Cl was ascribed to an enhancement in the open-circuit voltage and fill factor induced by the deeper energy level of the highest occupied molecular orbital and the favorable morphological features in its blended film with Y6.

Design of a Wearable System to Capture Physiological Data to Monitor Surgeons' Stress During Surgery.

The mental and physiological stress experienced by surgeons during operations has been identified as an important human factor that impacts surgical performance and patient safety. It is crucial to objectively measure and quantify surgeons' stress via physiological signals in order to enhance the understanding of how stress contributes to surgical outcomes. Current clinical and consumer devices for monitoring bio signals are not well adapted for use in the operating room; therefore, we designed an unobtrusive system, that measures select signals that correlate with stress and stores the data for integration into a data processing pipeline. Herein, we present a proof-of-concept device that captures data from ECG, EMG, EDA, and IMU sensors and initial testing results.

Light Polarization-Controlled Conversion of Ultrafast Coherent-Incoherent Exciton Dynamics in Few-Layer ReS2.

Coherent light-matter interaction can transiently modulate the quantum states of matter under nonresonant laser excitation. This phenomenon, called the optical Stark effect, is one of the promising candidates for realizing ultrafast optical switches. However, the ultrafast modulations induced by the coherent light-matter interactions usually involve unwanted incoherent responses, significantly reducing the overall operation speed. Here, by using ultrafast pump-probe spectroscopy, we suppress the incoherent response and modulate the coherent-to-incoherent ratio in the two-dimensional semiconductor ReS2. We selectively convert the coherent and incoherent responses of an anisotropic exciton state by solely using photon polarizations, improving the control ratio by 3 orders of magnitude. The efficient modulation was enabled by transient superpositions of differential spectra from two nondegenerate exciton states due to the light polarization dependencies. This work provides a valuable contribution toward realizing ideal ultrafast optical switches.

Generation, transport and detection of valley-locked spin photocurrent in WSe2-graphene-Bi2Se3 heterostructures.

Quantum optoelectronic devices capable of isolating a target degree of freedom (DoF) from other DoFs have allowed for new applications in modern information technology. Many works on solid-state spintronics have focused on methods to disentangle the spin DoF from the charge DoF1, yet many related issues remain unresolved. Although the recent advent of atomically thin transition metal dichalcogenides (TMDs) has enabled the use of valley pseudospin as an alternative DoF2,3, it is nontrivial to separate the spin DoF from the valley DoF since the time-reversal valley DoF is intrinsically locked with the spin DoF4. Here, we demonstrate lateral TMD-graphene-topological insulator hetero-devices with the possibility of such a DoF-selective measurement. We generate the valley-locked spin DoF via a circular photogalvanic effect in an electric-double-layer WSe2 transistor. The valley-locked spin photocarriers then diffuse in a submicrometre-long graphene layer, and the spin DoF is measured separately in the topological insulator via non-local electrical detection using the characteristic spin-momentum locking. Operating at room temperature, our integrated devices exhibit a non-local spin polarization degree of higher than 0.5, providing the potential for coupled opto-spin-valleytronic applications that independently exploit the valley and spin DoFs.

Control over Electron-Phonon Interaction by Dirac Plasmon Engineering in the Bi2Se3 Topological Insulator.

Understanding the mutual interaction between electronic excitations and lattice vibrations is key for understanding electronic transport and optoelectronic phenomena. Dynamic manipulation of such interaction is elusive because it requires varying the material composition on the atomic level. In turn, recent studies on topological insulators (TIs) have revealed the coexistence of a strong phonon resonance and topologically protected Dirac plasmon, both in the terahertz (THz) frequency range. Here, using these intrinsic characteristics of TIs, we demonstrate a new methodology for controlling electron-phonon interaction by lithographically engineered Dirac surface plasmons in the Bi2Se3 TI. Through a series of time-domain and time-resolved ultrafast THz measurements, we show that, when the Dirac plasmon energy is less than the TI phonon energy, the electron-phonon coupling is trivial, exhibiting phonon broadening associated with Landau damping. In contrast, when the Dirac plasmon energy exceeds that of the phonon resonance, we observe suppressed electron-phonon interaction leading to unexpected phonon stiffening. Time-dependent analysis of the Dirac plasmon behavior, phonon broadening, and phonon stiffening reveals a transition between the distinct dynamics corresponding to the two regimes as the Dirac plasmon resonance moves across the TI phonon resonance, which demonstrates the capability of Dirac plasmon control. Our results suggest that the engineering of Dirac plasmons provides a new alternative for controlling the dynamic interaction between Dirac carriers and phonons.

Antioxidant activities of ginseng seeds treated by autoclaving.

Ginseng seeds were treated with different autoclaving temperatures and autoclaving times, and extracted with 80% methanol to measure changes in antioxidant activity. The antioxidant activity of ginseng seeds treated by autoclaving was measured by 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, 2,2'-aziono-bis(3-ethylbenzthiazoline)-6-sulfonic acid radical scavenging activity, superoxide dismutase SOD-like activity, ferric reducing antioxidant power (FRAP), and total phenolic compound content. As autoclaving temperature and time were increased, the L lightness value decreased and the redness value tended to increase. Total phenolic compound content was about three times higher in ginseng seeds treated with autoclaving at 130℃ than in ginseng seeds that were not treated. DPPH radical scavenging activity and ABTS radical scavenging activity increased as autoclaving temperature and time were increased. In particular, when the concentration was 100 ppm, the ABTS radical scavenging activity was 91.80% in ginseng seeds treated by autoclaving at 130℃, which was the highest antioxidant activity. FRAP and SOD-like antioxidant activity tended to increase significantly as autoclaving temperature and time were increased.

Phytochemical characteristics of coffee bean treated by coating of ginseng extract.

THE PRINCIPAL OBJECTIVE OF THIS STUDY WAS TO ASSESS THE INSTRUMENTAL AND SENSORY CHARACTERISTICS OF GINSENG COFFEE WITH DIFFERENT RATIOS OF THE INGREDIENTS: type of coffee bean (Colombia, Brazil, and Indonesia), type of ginseng extract (white ginseng, red ginseng, and America ginseng) and concentration of ginseng extract (3, 6, and 9 w/v %). The sensory optimal condition of white ginseng coffee, red ginseng coffee and America ginseng coffee were as follows: 3% Indonesian coffee bean coated with 3% white ginseng extract, Colombian coffee bean coated with 6% red ginseng extract and Colombian coffee bean coated with 3% American ginseng extract, respectively. In particular, the Colombian coffee bean coated with 6% red ginseng extract had significantly higher scores than other samples in terms of flavor, taste, and overall preference. Additionally, the contents of total ginsenoside and total sugar and total phenolic compounds were also highest in the Colombian coffee bean coated with 6% red ginseng extract.