Link between T-Linear Resistivity and Quantum Criticality in Ambipolar Black Phosphorus.

The interplay between strong Coulomb interactions and kinetic energy leads to intricate many-body competing ground states owing to quantum fluctuations in 2D electron and hole gases. However, the simultaneous observation of quantum critical phenomena in both electron and hole regimes remains elusive. Here, we utilize anisotropic black phosphorus (BP) to show density-driven metal-insulator transition with a critical conductance ∼e2/h which highlights the significant role of quantum fluctuations in both hole and electron regimes. We observe a T-linear resistivity from the deep metallic phase to the metal-insulator boundary at moderate temperatures, while it turns to Fermi liquid behavior in the deep metallic phase at low temperatures in both regimes. An analysis of the resistivity suggests that disorder-dominated transport leads to T-linear behavior in the hole regime, while in the electron regime, the T-linear resistivity results from strong Coulomb interactions, suggestive of strange-metal behavior. Successful scaling collapse of the resistivity in the T-linear region demonstrates the link between quantum criticality and the T-linear resistivity in both regimes. Our study provides compelling evidence that ambipolar BP could serve as an exciting testbed for investigating exotic states and quantum critical phenomena in hole and electron regimes of 2D semiconductors.

Analysis of p-Type Doping in Graphene Induced by Monolayer-Oxidized TMDs.

Doping is one of the most difficult technological challenges for realizing reliable two-dimensional (2D) material-based semiconductor devices, arising from their ultrathinness. Here, we systematically investigate the impact of different types of nonstoichiometric solid MOx (M are W or Mo) dopants obtained by oxidizing transition metal dichalcogenides (TMDs: WSe2 or MoS2) formed on graphene FETs, which results in p-type doping along with disorders. From the results obtained in this study, we were able to suggest an analytical technique to optimize the optimal UV-ozone (UVO) treatment to achieve high p-type doping concentration in graphene FETs (∼2.5 × 1013 cm-2 in this study) without generating defects, mainly by analyzing the time dependency of D and D' peaks measured by Raman spectroscopy. Furthermore, an analysis of the structure of graphene sheets using TEM indicates that WOx plays a better protective role in graphene, compared to MoOx, suggesting that WOx is more effective for preventing the degradation of graphene during UVO treatment. To enhance the practical application aspect of our work, we have fabricated a graphene photodetector by selectively doping the graphene through oxidized TMDs, creating a p-n junction, which resulted in improved photoresponsivity compared to the intrinsic graphene device. Our results offer a practical guideline for the utilization of surface charge transfer doping of graphene toward CMOS applications.

Comparison of Perceived Importance and Performance of Community Pharmacists' Role in South Korea During the Coronavirus Disease 2019 Pandemic.

OBJECTIVE: This study aimed to identify the roles of community pharmacists (CPs) during the coronavirus disease 2019 (COVID-19) pandemic, the differences in their role performance compared with their perceived importance, and limiting factors. METHODS: A cross-sectional online survey of CPs was conducted. The CPs self-measured the importance and performance of each role during the pandemic using a 5-point Likert scale. A paired t-test was used to compare each role's importance and performance scores. A logistic regression analysis of the roles with low performance scores, despite their level of importance, was conducted to determine the factors affecting performance. The limiting factors were also surveyed. RESULTS: The 436 responses to the questionnaire were analyzed. The performance scores were significantly lower than the perceived importance scores for 15 of the 17 roles. The source and update frequency of COVID-19 information and participation in outreach pharmaceutical services were associated with low performance scores. Insufficient economic compensation, the lack of communication channels, and legal limitations were the limiting factors in performing the CPs' roles. CONCLUSIONS: The participation in outreach pharmaceutical services, economic compensation, and communication channel should be improved to motivate the CPs in performing their roles.

Probing Intrinsic Defect-Induced Trap States and Hopping Transport in Two-Dimensional PdSe2 Semiconductor Devices.

Palladium diselenide (PdSe2), as an emerging two-dimensional (2D) layered material, is gaining growing attention in nanoelectronics and optoelectronics due to its thickness-dependent band gap, high carrier mobility, and good air stability. However, its asymmetric pentagon structure is inclined to breed defects. Herein, the intrinsic Se vacancy-induced trap states and their influence on the hopping transport in PdSe2 are systematically investigated. We provide direct evidence that Se vacancies exist in the fresh PdSe2 samples, which results in the localized trapping states inside the band gap. For the few-layer PdSe2, at 77 K, the trap density (Dit) near the midgap is about 2.2 × 1013 cm-2 eV-1, whereas at 295 K, the Dit value increases to ∼7.1 × 1013 cm-2 eV-1. By comparison, the multilayer PdSe2 shows nonobvious temperature-dependent trap behaviors with almost unchanged Dit values of ∼8.1 × 1012 cm-2 eV-1 at midgap in the temperature range between 77 and 295 K. Thus, trap states in the few-layer PdSe2 are more vulnerable to temperature effect. Transport measurements demonstrated that both few-layer and multilayer PdSe2 field-effect transistor (FET) devices show n-type dominant ambipolar behaviors. The electron mobility in the multilayer PdSe2 FET is nearly 15-fold higher than that in the few-layer PdSe2 FET at 315 K, probably owing to the decreased effective mass and suppression of charge impurity scattering in the thicker channel material. However, both FET devices exhibit variable-range hopping over a temperature range from 77 to 240 K and thermally activated hopping at temperatures above 240 K. The hopping transport mechanism is strongly associated with the Se vacancy-induced localized states with poor screening and strong potential fluctuations. This study reveals the important role of structural defects in tailoring and improving the charge transport properties of PdSe2.

Recent Progress in 1D Contacts for 2D-Material-Based Devices.

Recent studies have intensively examined 2D materials (2DMs) as promising materials for use in future quantum devices due to their atomic thinness. However, a major limitation occurs when 2DMs are in contact with metals: a van der Waals (vdW) gap is generated at the 2DM-metal interfaces, which induces metal-induced gap states that are responsible for an uncontrollable Schottky barrier (SB), Fermi-level pinning (FLP), and high contact resistance (RC ), thereby substantially lowering the electronic mobility of 2DM-based devices. Here, vdW-gap-free 1D edge contact is reviewed for use in 2D devices with substantially suppressed carrier scattering of 2DMs with hexagonal boron nitride (hBN) encapsulation. The 1D contact further enables uniform carrier transport across multilayered 2DM channels, high-density transistor integration independent of scaling, and the fabrication of double-gate transistors suitable for demonstrating unique quantum phenomena of 2DMs. The existing 1D contact methods are reviewed first. As a promising technology toward the large-scale production of 2D devices, seamless lateral contacts are reviewed in detail. The electronic, optoelectronic, and quantum devices developed via 1D contacts are subsequently discussed. Finally, the challenges regarding the reliability of 1D contacts are addressed, followed by an outlook of 1D contact methods.

Pharmacokinetic properties of two erlotinib 150 mg formulations with a genetic effect evaluation in healthy Korean subjects.

BACKGROUND AND OBJECTIVE: Erlotinib is a drug used to treat non-small cell lung cancer, pancreatic cancer and several other types of cancer. It is a reversible tyrosine kinase inhibitor that acts on the epidermal growth factor receptor and inhibits cell proliferation, growth, migration, invasion and survival. This study was performed for the subsequent marketing of a test erlotinib formulation in Korea. We evaluated the comparative bioavailability and tolerability of the test and reference formulations in healthy adult volunteers. METHODS: A total of 46 healthy male subjects were enrolled in a single-dose, randomized, open-label, two-period, two-sequence, crossover, bioequivalence study. During each treatment period, subjects received 150 mg of erlotinib in either the test or reference formulation. There was a 2-week washout period between each period. Blood samples were obtained 15 times during each period, before dosing and 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, 24, 48, 72 and 96 h after oral administration. Plasma concentrations of erlotinib were determined using liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters, including maximum plasma concentration (C(max)), area under the plasma concentration-time curve to the last sampling time (AUC(t)), AUC from time zero to infinity (AUC(∞)), and time to reach C(max) (t(max)), were measured, and all treatment-emergent adverse events and their relationships with the study medications were recorded throughout the study. An additional analysis was performed to characterize the association between the cytochrome P450 (CYP) 1A1, CYP1A2 and CYP3A4 genotypes and the erlotinib pharmacokinetic parameters. RESULTS: A total of 41 subjects completed the study. There were no significant differences in the prevalence of adverse events between the two formulations, and there were no serious or unexpected adverse events during the study. Both formulations had very similar C(max), AUC, terminal half-life (t ½) and t(max) values. The 90% confidence intervals of the geometric least-squares mean ratios of the test to reference formulation were 1.09 (0.98-1.22) for C(max) and 1.10 (1.01-1.21) for AUCt. Statistical significance was observed between the CYP1A2*1M genotype and the erlotinib pharmacokinetic parameter, particularly C(max) (p = 0.015). CONCLUSIONS: This study suggests that the test and reference formulations of 150 mg erlotinib have similar pharmacokinetic characteristics. Both had no major safety issues and were well-tolerated. The test formulation met the regulatory criteria for assuming bioequivalence to the reference formulation for both AUCt and C max. The additional genetic analysis demonstrated that the major metabolic enzymes of erlotinib did not significantly affect erlotinib metabolism, with the exception of CYP1A2*1M.

Pharmacokinetic comparison study of a combination containing 500 mg of Naproxen and 20 mg of Esomeprazole: a randomized, single-dose, 2-way crossover, open-label study in healthy Korean men.

PURPOSE: Nonsteroidal anti-inflammatory drugs have been used for analgesic, anti-inflammatory, and antithrombotic effects, but they carry a risk of major gastrointestinal damage. This risk can be greatly reduced by the coadministration of inhibitors of gastric acid secretion, such as proton pump inhibitors. This study was performed for the subsequent marketing of a combination drug that contained 500 mg of naproxen and 20 mg of esomeprazole in Korea. We evaluated the comparative bioavailability and tolerability of the test and reference formulations in healthy men. METHODS: A total of 60 healthy men were enrolled in this single-dose, randomized, open-label, 2-period, 2-sequence, crossover study. During each period, men received a combination of 500 mg of naproxen and 20 mg of esomeprazole for test or reference, and between each period, there was a 1-week washout period. Blood samples were obtained 21 times throughout each period before dosing and 0.17, 0.33, 0.5, 0.75, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 8, 10, 12, 24, 48, and 72 hours after oral administration. Plasma concentrations were determined using LC-MS/MS. The pharmacokinetic parameters, including Cmax, AUC0-t, AUC0-∞, and Tmax, were measured, and all treatment-emergent adverse events and their associations with the study medications were recorded throughout the entire study. FINDINGS: A total of 59 men completed the study. No significant differences were found in the prevalence of AEs between the 2 formulations. In addition, there were no serious or unexpected AEs during the study. Both formulations had very similar Cmax, AUC, and t½ values, but the Tmax of naproxen appeared earlier in the test formulation than in the reference formulation and that of esomeprazole appeared later in the test formulation than in the reference formulation. IMPLICATIONS: This study suggests that the test and reference formulations of a combination of 500 mg of naproxen and 20 mg of esomeprazole are bioequivalent in the extent of absorption and peak concentration. We anticipate that the test formulation will treat those who need relief from pain and inflammation and will decrease the risk of developing gastric ulcers. cris.nih.go.kr identifier: KCT0001117.

Pharmacokinetic comparisons between two formulations containing 100 mg of miglitol in healthy male Korean volunteers: a randomized, open-label, single-dose, two-period, two-sequence crossover bioequivalence study.

BACKGROUND: Miglitol is an α-glucosidase inhibitor (AGI) used as an antihyperglycemic agent in the treatment of type 2 diabetes mellitus. The mechanism is that miglitol binds to and inhibits the α-glucosidase reversibly in the proximal intestine. Thus, carbohydrates not digested in the upper small intestine are transported to the lower intestine where they are eventually digested. OBJECTIVE: This study was performed for the subsequent marketing of the test miglitol formulation in Korea. We evaluated the comparative bioavailability and tolerability of the test and reference formulations in healthy male adult volunteers. METHODS: A total of 40 healthy adult subjects were enrolled in this single-dose, randomized, open-label, 2-period, 2-sequence, crossover bioequivalence study. During each period, subjects received 100 mg of miglitol test or reference. Blood samples from the subjects were obtained before dosing at 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 9, and 12 hours after oral drug administration. Plasma concentrations were determined by using liquid chromatography/mass spectrometry/mass spectrometry (LC-MS/MS). The PK parameters including AUCt, AUC∞, Cmax, and tmax were measured and all treatment-emergent adverse events (TEAEs) and their relationships to study these medications were recorded throughout the entire study. RESULTS: A total of 40 healthy adult male Korean subjects were enrolled in the study and randomized into two treatment groups. Ultimately, 33 subjects completed the study. During each treatment period, blood samples were collected at specific time intervals from 0 to 12 hours after administration of a single drug dose. The PK parameters including AUCt, AUC∞, Cmax, and tmax were calculated and the 90% CIs of the ratio (test/reference) of the parameters were obtained by analysis of variance (ANOVA) on logarithmically transformed data. The 90% CIs of the geometric mean ratios for the test to reference formulations were as follows: 1.05 (0.97 - 1.13) for AUCt and 1.05 (0.96 - 1.14) for Cmax. Statistical analysis confirmed that the 90% CIs for these PK parameters were within the commonly accepted bioequivalence range of 0.8 - 1.25. There were no serious or unexpected TEAEs during the study. CONCLUSIONS: In the healthy adult Korean subjects, the test and reference formulations had similar PK parameters and similar plasma concentration-time profiles. The test formulation of miglitol met the Korean regulatory criteria (AUCt and Cmax) for assuming bioequivalence and both formulations were generally well-tolerated. The CRiS identifiers: KCT0000770.

Pulchellamin G, an amino acid-sesquiterpene lactone, from Saussurea pulchella suppresses lipopolysaccharide-induced inflammatory responses via heme oxygenase-1 expression in murine peritoneal macrophages.

Saussurea pulchella (Asteraceae) is widely distributed in Korea and has been used in Korean folk medicine for the treatment of inflammation, hypertension, hepatitis, and arthritis. Pulchellamin G is an amino acid-sesquiterpene lactone conjugate isolated from S. pulchella. In the present study, we focused on the anti-inflammatory effect of pulchellamin G, which acts by inducing the expression of heme oxygenase (HO)-1. HO-1 plays important roles in cytoprotection since it has antioxidant, anti-inflammatory, antiproliferative, and antiapoptotic properties. Pulchellamin G inhibited the mRNA and protein expression of inducible nitric oxide synthase (iNOS), iNOS-derived nitric oxide (NO), and cyclooxygenase (COX)-2 and COX-derived prostaglandin E2 (PGE2) production in lipopolysaccharide (LPS)-stimulated murine peritoneal macrophages. The compound also reduced tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) production and suppressed the phosphorylation and degradation of IκB-α and nuclear translocation of p65 in murine peritoneal macrophages in response to LPS stimulus. The inhibitory effects of pulchellamin G on nuclear factor kappa B (NF-κB) translocation was impaired by co-treatment of the cells with HO activity inhibitor tin protoporphyrin (SnPP). By using SnPP, we verified that the inhibitory effects of pulchellamin G on the pro-inflammatory mediators NO, PGE2, TNF-α, and IL-1ß are associated with induction of HO-1 expression. Our data suggest that pulchellamin G might have potent therapeutic effects and it should be considered in the development of treatments for various inflammatory diseases.

Santamarin, a sesquiterpene lactone isolated from Saussurea lappa, represses LPS-induced inflammatory responses via expression of heme oxygenase-1 in murine macrophage cells.

Saussurea lappa C.B. Clarke (Compositae) is indigenous to India and Pakistan. The dried root of S. lappa has been traditionally used for alleviating pain in abdominal distention and tenesmus, indigestion with anorexia, dysentery, nausea, and vomiting. Santamarin is a sesquiterpene lactone isolated from S. lappa. In the present study, santamarin inhibited inducible nitric oxide synthase (iNOS) protein, reduced iNOS-derived nitric oxide (NO), suppressed COX-2 protein and reduced COX-derived PGE(2) production in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and murine peritoneal macrophages. Similarly, santamarin reduced tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) production. In addition, santamarin suppressed the phosphorylation and degradation of IκB-α as well as the nuclear translocation of p65 in response to LPS in RAW264.7 cells. Furthermore, santamarin induced heme oxygenase (HO)-1 expression mRNA and protein level that plays a cytoprotective role against inflammation. The induction of HO-1 is primarily regulated at the transcriptional level, and its induction by various agents is mediated by the nuclear transcription factor E2-related factor 2 (Nrf2), master regulator of antioxidant responses. Unbound Nrf2 translocates into the nucleus and binds to the antioxidant response element (ARE) in the upstream promoter region of many antioxidative genes, where it initiates their transcription. The effects of santamarin on LPS-induced NO, PGE(2), TNF-α, and IL-1ß production were partially reversed by the HO-1 inhibitor, tin protoporphyrin (SnPP). Therefore, our data suggest that the anti-inflammatory effect of santamarin in macrophages may be exerted through a novel mechanism that involves HO-1 expression.

Involvement of Heme Oxygenase-1 Induction in the Cytoprotective and Immunomodulatory Activities of Viola patrinii in Murine Hippocampal and Microglia Cells.

A number of diseases that lead to injury of the central nervous system are caused by oxidative stress and inflammation in the brain. In this study, NNMBS275, consisting of the ethanol extract of Viola patrinii, showed potent antioxidative and anti-inflammatory activity in murine hippocampal HT22 cells and BV2 microglia. NNMBS275 increased cellular resistance to oxidative injury caused by glutamate-induced neurotoxicity and reactive oxygen species generation in HT22 cells. In addition, the anti-inflammatory effects of NNMBS275 were demonstrated by the suppression of proinflammatory mediators, including proinflammatory enzymes (inducible nitric oxide synthase and cyclooxygenase-2) and cytokines (tumor necrosis factor-α and interleukin-1ß). Furthermore, we found that the neuroprotective and anti-inflammatory effects of NNMBS275 were linked to the upregulation of nuclear transcription factor-E2-related factor 2-dependent expression of heme oxygenase-1 in HT22 and BV2 cells. These results suggest that NNMBS275 possesses therapeutic potential against neurodegenerative diseases that are induced by oxidative stress and neuroinflammation.

Sauchinone suppresses pro-inflammatory mediators by inducing heme oxygenase-1 in RAW264.7 macrophages.

Sauchinone, a biologically active lignan isolated from the roots of Saururus chinensis (LOUR.) BAILL. (Saururaceae), is reported to exert a variety of biological activities, such as hepatoprotective, anti-inflammatory actions and inhibitory effects on bone resorption. In this study, we investigated the effect of sauchinone in suppressing cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression, leading to a reduction in COX-2-derived prostaglandin E(2) (PGE(2)) and iNOS-derived nitric oxide (NO) production in lipopolysaccharide (LPS) stimulated RAW264.7 macrophages. Present study also demonstrates the effects of sauchinone in inducing heme oxygenase-1 (HO-1) expression and an increase in heme oxygenase (HO) activity in RAW264.7 macrophages. The effects of sauchinone on LPS-induced PGE(2), NO, tumor necrosis factor-α (TNF-α) and interlukine-1ß (IL-1ß) production were partially reversed by the HO-1 inhibitor Tin protoporphyrin was also seen in this study. In addition, we found that treatment with extracellular signal-regulated kinase (ERK) inhibitor (PD98059) reduced sauchinone-induced HO-1 expression. Sauchinone also increased ERK phosphorylation. These results suggest that sauchinone inhibits pro-inflammatory mediators through expression of anti-inflammatory HO-1 via ERK pathway.