Impedance Response of a Thin Film on an Electrode: Deciphering the Influence of the Double Layer Capacitance.

The different contributions of the interfacial capacitance are identified in the case of passive materials or thin protective coatings deposited on the electrode surface. The method is based on a graphical analysis of the EIS results to determine both the passive-film capacitance in the high-frequency domain and the double-layer capacitance in the low-frequency domain. The proposed analysis is shown to be independent of the physicochemical origins of the frequency dispersion of the interfacial capacitances which results, from an analysis point of view of the experimental results, in the use of a constant-phase element However, for a correct evaluation of the thin-film properties such as its thickness, the high-frequency data must be corrected for the double-layer contribution. In particular, it is shown that if the double-layer capacitance gives a frequency-dispersed response, it is necessary to correct the high-frequency part for the double-layer constant-phase elements. This is first demonstrated on synthetic data and then used for the determination of the thickness of thin oxide film formed on Al in neutral pH solution.

Calosides A-F, Cardenolides from Calotropis gigantea and Their Cytotoxic Activity.

Phytochemical analysis of the roots of Calotropis gigantea led to the isolation of six new cardenolide glycosides, calosides A-F (1-6), and five known cardenolides (7-11). The structures of 1-6 were elucidated based on NMR and ECD spectroscopic data interpretation. Caloside D (4) is the first naturally occurring example of a cardenolide containing a C-8/C-19 oxygen bridge. In turn, calosides E (5) and F (6) represent the first naturally occurring 3-epi-cannogenol diglycosides having potent cytotoxicity against the PANC-1 cell line (IC50, 0.081 and 0.070 µM, respectively) and HeLa (IC50, both 0.17 µM) cells, under normoglycemic conditions.

Phytochemical and cytotoxic studies on the leaves of Calotropis gigantea.

A new lignan, 9'-methoxypinoresinol (1), and two new glycosylated 5-hydroxymethylfurfurals, calofurfuralside A (2), and calofurfuralside B (3), together with nine known compounds (4-12) have been isolated from the active fractions, CHCl3 (IC50, 0.32µgmL-1) and EtOAc (IC50, 0.55µgmL-1) fractions of the leaves of Calotropis gigantea. Their structures were elucidated based on NMR and MS data. Among the isolated compounds, compounds 1 and 9 exhibited potent cytotoxicity against PANC-1 human pancreatic cancer cell line under the normoglycemic condition with IC50 values of 3.7 and 3.3µM, respectively. 9'-Methoxypinoresinol (1) significantly inhibited the colony formation of PANC-1 cells in a concentration-dependent manner.

Chemical Constituents of Propolis from Vietnamese Trigona minor and Their Antiausterity Activity against the PANC-1 Human Pancreatic Cancer Cell Line.

The ethanol extract of propolis from the Vietnamese stingless bee Trigona minor possessed potent preferential cytotoxicity against PANC-1 human pancreatic cancer cells in nutrient-deprived medium, with a PC50 value of 14.0 µg/mL. Chemical investigation of this extract led to the isolation of 15 cycloartane-type triterpenoids, including five new compounds (1-5), and a lanostane-type triterpenoid. The structures of the new compounds were elucidated on the basis of NMR spectroscopic analysis. Among the isolated compounds, 23-hydroxyisomangiferolic acid B (5) and 27-hydroxyisomangiferolic acid (13) exhibited the most potent preferential cytotoxicity against PANC-1 human pancreatic cancer cells under nutrition-deprived conditions, with PC50 values of 4.3 and 3.7 µM, respectively.

Quinoliniumolate and 2H-1,2,3-Triazole Derivatives from the Stems of Paramignya trimera and Their α-Glucosidase Inhibitory Activities: In Vitro and in Silico Studies.

From a CHCl3-soluble extract of the stems of Paramignya trimera, two new alkaloids, (E)-2-(prop-1-enyl)-N-methylquinolinium-4-olate (1) and (R)-2-ethylhexyl 2H-1,2,3-triazole-4-carboxylate (2), were isolated. Their structures were elucidated based on the spectroscopic data interpretation. Compound 2 possesses α-glucosidase inhibitory activity, with an IC50 value of 137.9 µM. Molecular docking studies of 1 and 2 with human maltase-glucoamylase (MGAM) were performed for the first time; thus, the 2,3-diH+-1H-1,2,3-triazolium cation (2i) showed good interactions with both MGAM-N (2QMJ) and -C (3TOP) terminal subunits.

Lignans from the Roots of Taxus wallichiana and Their α-Glucosidase Inhibitory Activities.

From an EtOAc-soluble extract of the roots of Taxus wallichiana, six new (1-6) and 11 known lignans were isolated. The structures of the new compounds were elucidated based on interpretation of spectroscopic data. (+)-7'-epi-Tsugacetal (1) is a rare aryltetralin-type lignan having a cis-orientation of H-7' and H-8'. Compounds 3-6 were identified as the first naturally occurring tetrahydrofuranoid lignans having a cis-orientation of H-7 and H-8. All tested compounds were found to possess α-glucosidase inhibitory activity, with formosanol (9) showing the most potent effect with an IC50 value of 35.3 µM.

Artocarmins G-M, Prenylated 4-Chromenones from the Stems of Artocarpus rigida and Their Tyrosinase Inhibitory Activities.

Phytochemical analysis of an EtOAc extract of the stems of Artocarpus rigida led to the identification of seven new prenylated 4-chromenones, artocarmins G-M (1-7), and nine known compounds (8-17). Their structures were identified based on physical data analysis. In the tyrosinase inhibitory activity test, norartocarpetin (8) displayed the strongest effect, with an IC50 value of 0.023 µM.

Biogeography of squirrel monkeys (genus Saimiri): South-central Amazon origin and rapid pan-Amazonian diversification of a lowland primate.

The squirrel monkey, Saimiri, is a pan-Amazonian Pleistocene radiation. We use statistical phylogeographic methods to create a mitochondrial DNA-based timetree for 118 squirrel monkey samples across 68 localities spanning all Amazonian centers of endemism, with the aim of better understanding (1) the effects of rivers as barriers to dispersal and distribution; (2) the area of origin for modern Saimiri; (3) whether ancestral Saimiri was a lowland lake-affiliated or an upland forest taxa; and (4) the effects of Pleistocene climate fluctuation on speciation. We also use our topology to help resolve current controversies in Saimiri taxonomy and species relationships. The Rondônia and Inambari centers in the southern Amazon were recovered as the most likely areas of origin for Saimiri. The Amazon River proved a strong barrier to dispersal, and squirrel monkey expansion and diversification was rapid, with all speciation events estimated to occur between 1.4 and 0.6Ma, predating the last three glacial maxima and eliminating climate extremes as the main driver of squirrel monkey speciation. Saimiri expansion was concentrated first in central and western Amazonia, which according to the "Young Amazon" hypothesis was just becoming available as floodplain habitat with the draining of the Amazon Lake. Squirrel monkeys also expanded and diversified east, both north and south of the Amazon, coincident with the formation of new rivers. This evolutionary history is most consistent with a Young Amazon Flooded Forest Taxa model, suggesting Saimiri has always maintained a lowland wetlands niche and was able to greatly expand its range with the transition from a lacustrine to a riverine system in Amazonia. Saimiri vanzolinii was recovered as the sister group to one clade of Saimiri ustus, discordant with the traditional Gothic vs. Roman morphological division of squirrel monkeys. We also found paraphyly within each of the currently recognized species: S. sciureus, S. ustus, and S. macrodon. We discuss evidence for taxonomic revision within the genus Saimiri, and the need for future work using nuclear markers.

A qualitative study on stress, coping strategies and feasibility of music intervention among women with cancer receiving chemotherapy during COVID-19 pandemic in Vietnam.

Breast and gynaecological cancer (BGC) patients receiving chemotherapy may experience high levels of stress during the COVID-19 pandemic. Music interventions may be effective in lowering their stress levels. This study explored stressors, coping strategies, and the feasibility of music interventions among BGC patients in Vietnam. An exploratory qualitative study with individual face-to-face semi-structured interviews was conducted. A convenience sample of BGC patients receiving chemotherapy was recruited from the oncology centre of a public hospital in Vietnam. Twenty patients were interviewed with open-ended questions developed based on the transactional model of stress and coping to explore stress-causing factors and coping strategies and based on guidelines for music therapy practice to explore their music preferences and perceptions. Field notes and interview transcripts were analysed following the qualitative content analysis approach. Two stressor themes were identified: undesirable experiences during treatment and patients' inability to fulfil their own roles and responsibilities. Our findings revealed a new coping strategy-self-realisation of responsibilities towards the family-that is not listed in the transactional model of stress and coping. Future psychological interventions for stress management among BGC patients should focus on raising the patients' awareness of their values and responsibilities towards their families. Three categories of preferred music genres for stress reduction were identified: religious, softly melodic, and revolutionary music. The patients were aware of the positive effects of music and had different musical preferences. This study also explored the acceptance of music interventions and facilitators and barriers to implementing them among BGC patients in Vietnam. The findings suggest that before implementing music interventions, the musical preferences, religions, and beliefs of each individual should be considered to achieve desirable results. Music interventions for BGC patients receiving chemotherapy in Vietnam are feasible. Further intervention studies are needed to evaluate their effectiveness.

A new ß-carboline-type alkaloid from the flowers of Calotropis gigantea (L.) W.T.Aiton.

In our antioxidant screening of some Vietnamese plant extracts, the CHCl3-soluble fraction from Calotropis gigantea (L.) W.T.Aiton flowers showed moderate DPPH free radical scavenging activity with an IC50 value of 55.8 µg/mL. Thus, a further phytochemical study was carried out to obtain five alkaloids, including a new ß-carboline-type alkaloid, caloside H (1). These known compounds were identified as 5-hydroxy-(2-methoxymethyl)pyridine (2), nicotinic acid (3), p-(acetylamino)phenol (4), and thymine (5). These structures were determined based on the NMR spectroscopic analysis. In antioxidant assay, caloside H at concentration of 100 µM showed DPPH radical scavenging capacity with a percentage of inhibition of 40.2%. In addition, a plausible biosynthetic pathway for the formation of caloside H was proposed based on the Schiff base formation and Mannich-like reaction.

RENEB Inter-Laboratory Comparison 2021: Inter-Assay Comparison of Eight Dosimetry Assays.

Tools for radiation exposure reconstruction are required to support the medical management of radiation victims in radiological or nuclear incidents. Different biological and physical dosimetry assays can be used for various exposure scenarios to estimate the dose of ionizing radiation a person has absorbed. Regular validation of the techniques through inter-laboratory comparisons (ILC) is essential to guarantee high quality results. In the current RENEB inter-laboratory comparison, the performance quality of established cytogenetic assays [dicentric chromosome assay (DCA), cytokinesis-block micronucleus assay (CBMN), stable chromosomal translocation assay (FISH) and premature chromosome condensation assay (PCC)] was tested in comparison to molecular biological assays [gamma-H2AX foci (gH2AX), gene expression (GE)] and physical dosimetry-based assays [electron paramagnetic resonance (EPR), optically or thermally stimulated luminescence (LUM)]. Three blinded coded samples (e.g., blood, enamel or mobiles) were exposed to 0, 1.2 or 3.5 Gy X-ray reference doses (240 kVp, 1 Gy/min). These doses roughly correspond to clinically relevant groups of unexposed to low exposed (0-1 Gy), moderately exposed (1-2 Gy, no severe acute health effects expected) and highly exposed individuals (>2 Gy, requiring early intensive medical care). In the frame of the current RENEB inter-laboratory comparison, samples were sent to 86 specialized teams in 46 organizations from 27 nations for dose estimation and identification of three clinically relevant groups. The time for sending early crude reports and more precise reports was documented for each laboratory and assay where possible. The quality of dose estimates was analyzed with three different levels of granularity, 1. by calculating the frequency of correctly reported clinically relevant dose categories, 2. by determining the number of dose estimates within the uncertainty intervals recommended for triage dosimetry (±0.5 Gy or ±1.0 Gy for doses <2.5 Gy or >2.5 Gy), and 3. by calculating the absolute difference (AD) of estimated doses relative to the reference doses. In total, 554 dose estimates were submitted within the 6-week period given before the exercise was closed. For samples processed with the highest priority, earliest dose estimates/categories were reported within 5-10 h of receipt for GE, gH2AX, LUM, EPR, 2-3 days for DCA, CBMN and within 6-7 days for the FISH assay. For the unirradiated control sample, the categorization in the correct clinically relevant group (0-1 Gy) as well as the allocation to the triage uncertainty interval was, with the exception of a few outliers, successfully performed for all assays. For the 3.5 Gy sample the percentage of correct classifications to the clinically relevant group (≥2 Gy) was between 89-100% for all assays, with the exception of gH2AX. For the 1.2 Gy sample, an exact allocation to the clinically relevant group was more difficult and 0-50% or 0-48% of the estimates were wrongly classified into the lowest or highest dose categories, respectively. For the irradiated samples, the correct allocation to the triage uncertainty intervals varied considerably between assays for the 1.2 Gy (29-76%) and 3.5 Gy (17-100%) samples. While a systematic shift towards higher doses was observed for the cytogenetic-based assays, extreme outliers exceeding the reference doses 2-6 fold were observed for EPR, FISH and GE assays. These outliers were related to a particular material examined (tooth enamel for EPR assay, reported as kerma in enamel, but when converted into the proper quantity, i.e. to kerma in air, expected dose estimates could be recalculated in most cases), the level of experience of the teams (FISH) and methodological uncertainties (GE). This was the first RENEB ILC where everything, from blood sampling to irradiation and shipment of the samples, was organized and realized at the same institution, for several biological and physical retrospective dosimetry assays. Almost all assays appeared comparably applicable for the identification of unexposed and highly exposed individuals and the allocation of medical relevant groups, with the latter requiring medical support for the acute radiation scenario simulated in this exercise. However, extreme outliers or a systematic shift of dose estimates have been observed for some assays. Possible reasons will be discussed in the assay specific papers of this special issue. In summary, this ILC clearly demonstrates the need to conduct regular exercises to identify research needs, but also to identify technical problems and to optimize the design of future ILCs.

School problems among left-behind children of labor migrant parents: a study in Vietnam.

BACKGROUND: Many studies have shown the effects of parental migration on the psychological and daily life of left-behind children (LBC) of labor migrant parents, but the results on school-related problems of LBC remain inconsistent. Additionally, there is a dearth of research on the factors affecting school problems among LBC, especially in the socio-cultural context of Vietnam. The purpose of this study was to confirm the school problems encountered by LBC in comparison with non-left-behind children (non-LBC). The study also aimed to examine variables of bonding of caregivers with children and resilience of children affecting school problems of LBC. PARTICIPANTS AND PROCEDURE: The convenient sampling approach was used in the study. The study sample included 792 Vietnamese school students (Mage = 12.65, SD = 1.60), with 439 children of labor migrant parents and a control group of 353 children of non-migrant parents. The School Problem Questionnaire, Parental Bonding Instrument and the Resilience Scale were employed in this study. RESULTS: There was no difference in school problems between the LBC and non-LBC groups. Resilience by goal planning (RGP), resilience by affect control (RAC), and resilience by family support (RFS) were identified as protective variables for children to overcome difficulties encountered in schools, with regression coefficients of -.21, -.33 and -.20, respectively. Meanwhile, bonding of caregivers with children by control (BCCo), and resilience by positive thinking (RPT) were found to be factors that increase school problems among LBC with the same regression coefficient of .12. CONCLUSIONS: Activities to support LBC should pay attention to improving resilience, namely affect control, goal planning, and promoting the role of caregivers for LBC.

A new 7',9-epoxylignan from the stems of Salacia chinensis.

Bioactivity-guided isolation of the CHCl3-soluble fraction of the stems of Salacia chinensis L. (Celastraceae) was carried out to obtain a new 7',9-epoxylignan (1) and three 7,9':7',9-diepoxylignans (2-4). The absolute configuration of 1 was elucidated based on NMR and ECD spectroscopic data interpretation. All isolated lignans showed intermediate α-glucosidase inhibitory activity with the IC50 values ranging from 28.5 to 85.6 µM.

Exposure to sexually explicit Internet material among adolescents: a study in Vietnam.

BACKGROUND: With the influence of Confucian culture, sex is often considered a taboo subject in Vietnam. This study aimed to examine the prevalence of exposure to sexually explicit Internet material (SEIM) among adolescents in Vietnam, as well as the factors affecting exposure to SEIM. PARTICIPANTS AND PROCEDURE: The sample consisted of 886 Vietnamese adolescents (58.10% female) aged 15 to 18 years (M = 16.72, SD = 0.72). The survey was adapted from the study of Van Ouytsel, Ponnet and Walrave to assess the frequency of exposure to SEIM. Several measurement scales of factors affecting exposure to SEIM among adolescents were used including the Perceived Realism of SEIM, the Sexual Sensation Seeking Scale, the Family Cohesion and the Parental Monitoring Scale. RESULTS: The overall prevalence of exposure to SEIM was 84.10%, with a gender difference: 89.80% in males and 80.00% in females. The prevalence of passive exposure to SEIM was 58.30%, higher than 41.70% for active exposure. Perceived realism of SEIM, sexual sensation seeking and Internet usage time for entertainment are factors affecting frequencies of exposure to SEIM among adolescents, with ß coefficient values of .29, .18 and .16 respectively. CONCLUSIONS: The majority of children in this study reported SEIM exposure. Parents, schools and other stakeholders should pay attention to sex education for children early on, diversifying forms and subjects of sex education. The content of sex education should emphasize the responsibility in the decisions made by children related to sex.

Diarylalkanoids as Potent Tyrosinase Inhibitors from the Stems of Semecarpus caudata.

From a CHCl3-soluble extract of the stems of Semecarpus caudata (Anacardiaceae), two new diarylalkanoids, semedienone (1) and semetrienone (2), were isolated. Their structures were elucidated based on NMR spectroscopic data interpretation. These compounds possess strong tyrosinase inhibitory activity with the IC50 values of 0.033 and 0.11 µM, respectively. Docking studies of 1 and 2 with oxy-tyrosinase were carried out to analyze their interactions. Accordingly, semedienone (1) showed good interactions with the peroxide group and amino acid residues. The biosynthesis of the isolated diarylalkanoids was proposed.

A new cytotoxic cardenolide from the roots of Calotropis gigantea.

Bioactivity-guided isolation of the CHCl3-soluble fraction of the roots of Calotropis gigantea was carried out to obtain a new cardenolide glycoside, caloside G. Its absolute structure was elucidated based on NMR and ECD spectroscopic data interpretation. Caloside G showed noteworthy cytotoxicity against the PANC-1 human pancreatic and HeLa human cervical carcinoma cell lines, with the submicromolar IC50 values of 0.038 and 0.09 µM, respectively.

Hydrothermally synthesized nanostructured LiMnxFe1-xPO4 (x = 0-0.3) cathode materials with enhanced properties for lithium-ion batteries.

Nanostructured cathode materials based on Mn-doped olivine LiMnxFe1-xPO4 (x = 0, 0.1, 0.2, and 0.3) were successfully synthesized via a hydrothermal route. The field-emission scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyzed results indicated that the synthesized LiMnxFe1-xPO4 (x = 0, 0.1, 0.2, and 0.3) samples possessed a sphere-like nanostructure and a relatively homogeneous size distribution in the range of 100-200 nm. Electrochemical experiments and analysis showed that the Mn doping increased the redox potential and boosted the capacity. While the undoped olivine (LiFePO4) had a capacity of 169 mAh g-1 with a slight reduction (10%) in the initial capacity after 50 cycles (150 mAh g-1), the Mn-doped olivine samples (LiMnxFe1-xPO4) demonstrated reliable cycling tests with negligible capacity loss, reaching 151, 147, and 157 mAh g-1 for x = 0.1, 0.2, and 0.3, respectively. The results from electrochemical impedance spectroscopy (EIS) accompanied by the galvanostatic intermittent titration technique (GITT) have resulted that the Mn substitution for Fe promoted the charge transfer process and hence the rapid Li transport. These findings indicate that the LiMnxFe1-xPO4 nanostructures are promising cathode materials for lithium ion battery applications.

Panduratins Q-Y, dimeric metabolites from Boesenbergia rotunda and their antiausterity activities against the PANC-1 human pancreatic cancer cell line.

A methanolic extract of the rhizomes of Boesenbergia rotunda showed potent preferential cytotoxicity against PANC-1 human pancreatic cancer cells under nutrient deficiency conditions with a PC50 value of 6.6 µg/mL. Bioactivity-guided phytochemical investigation of the rhizomes of B. rotunda led to the isolation of nine undescribed dimeric metabolites, panduratins Q-Y. Their structures were elucidated based on NMR, MS, and ECD spectroscopic data interpretation. Panduratins Q-S and U-W exhibited potent cytotoxicity towards PANC-1 cell line with the PC50 values ranging from 0.8 to 6.3 µM. Panduratin W, which possessed a cyclohexenylchalcone-linked flavanone skeleton, showed the most cytotoxicity with a PC50 value of 0.8 µM under nutrient-deprived medium.

Tyrosinase Inhibitors from the Stems of Streblus Ilicifolius.

Two new stilbene derivatives, named strebluses C and D, were isolated from the EtOAc-soluble fraction of the stems of Streblus ilicifolius (Moraceae). Its absolute configuration was elucidated based on NMR spectroscopic data interpretation and optical rotation calculation. Streblus C possesses strong tyrosinase inhibitory activity with an IC50 value of 0.01 µM. Docking studies of 1 and 2 with oxy-tyrosinase were carried out to analyze their interactions. The analysis of the docked poses confirmed that 1 showed better binding affinity for oxy-tyrosinase than that of 2.

Structure-based discovery of interleukin-33 inhibitors: a pharmacophore modelling, molecular docking, and molecular dynamics simulation approach.

Interleukin (IL)-33 is a new cytokine of the IL-1 family that is related to several inflammatory and autoimmune diseases. IL-33 binds to its ST2 receptor and leads to biological responses thereof. Currently, no drugs have been approved for the treatment of IL-33 related diseases. The aim of this study was to search for small molecules that inhibit the protein-protein interaction between IL-33 and ST2. A virtual screening was first performed to identify potential molecules that can bind IL-33. By analysing the interactions between key residues in the complex of IL-33/ST2, two pharmacophore hypotheses were then generated based on the 'mimicry' and 'pair-rule' principles. From a database of 62,074 compounds, 60 molecules satisfying the pharmacophore models were identified and docked to IL-33. Among 35 compounds successfully docked into the protein, 9 potential ligands in complex with IL-33 were selected for further analysis by molecular dynamics simulations. Based on the stability of the complexes and the interactions of each ligand with the key residues of IL-33, two compounds DB00158 and DB00642 were identified as the most potential inhibitors that can be further investigated as promising novel IL-33 inhibitory drugs.