A SURVEY ON COMMON ERRORS IN STUDYING SPEAKING SKILL OF ENGLISH-MAJORED FRESHMEN AT TAY DO UNIVERSITY, VIETNAM

Speaking is regarded as the most important aspect of communication skills, and it contributes to the success of language learners in their studies and careers, as well as the success of teachers in their teaching process. However, English-majored students, especially English-majored freshmen, usually face some errors in speaking English. Consequently, this research, entitled "A Survey on Common Errors in Studying Speaking Skills of English-majored Freshmen at Tay Do University" was conducted to figure out some common problems in speaking English that these English-majored students have encountered. The participants of this research were 80 students from two classes, English 15A and English 15B, at Tay Do University. The main research instrument for collecting the data was a questionnaire. The findings of this research pointed out the participants’ errors in speaking skills problems (pronunciation, grammar tense, pronunciation, mother tongue, vocabulary) and psychological problems (anxiety of error, lack of motivation, shyness, lack of confidence). The results showed that the students had errors in their speaking skills. Thanks to the results, some useful solutions were proposed for English-majored students.  Article visualizations

Numerical modeling of thermal dust polarization from aligned grains in the envelope of evolved stars with updated POLARIS

Magnetic fields are thought to influence the formation and evolution of evolved star envelopes. Thermal dust polarization from magnetically aligned grains is potentially a powerful tool for probing magnetic fields and dust properties in these circumstellar environments. In this paper, we present numerical modeling of thermal dust polarization from the envelope of IK Tau using the magnetically enhanced radiative torque (MRAT) alignment theory implemented in our updated POLARIS code. Due to the strong stellar radiation field, the minimum size required for RAT alignment of silicate grains is $\sim 0.005 - 0.05\,\rm\mu m$. Additionally, ordinary paramagnetic grains can achieve perfect alignment by MRAT in the inner regions of $r < 500\,\rm au$ due to stronger magnetic fields of $B\sim 10$ mG - 1G, producing thermal dust polarization degree of $\sim 10\,\%$. The polarization degree can be enhanced to $\sim 20-40\%$ for grains with embedded iron inclusions. We also find that the magnetic field geometry affects the alignment size and the resulting polarization degree due to the projection effect in the plane-of-sky. We also study the spectrum of polarized thermal dust emission and find the increased polarization degree toward $\lambda > 50\,\rm\mu m$ due to the alignment of small grains by MRAT. Furthermore, we investigate the impact of rotational disruption by RATs (RAT-D) and find the RAT-D effect cause a decrease in the dust polarization fraction. Finally, we compare our numerical results with available polarization data observed by SOFIA/HAWC+ for constraining dust properties, suggesting grains are unlikely to have embedded iron clusters and might have slightly elongated shapes. Our modeling results suggest further observational studies at far-infrared/sub-millimeter wavelengths to understand the properties of magnetic fields and dust in AGB envelopes.Comment: 27 pages, 23 figures, 1 table, to be submitte

ANTIMICROBIAL COMPOUNDS FROM RHIZOPHORA STYLOSA

(6S,7E,9R)-6,9-dihydroxy-4,7-megastiymadien-3-one 9-O-[α-L-arabinopyranosyl-(l→6)-β-D-glucopyranoside] (1), blumenol A (2), and kaempferol 3-rutinoside (3) were isolated from the methanol extract of the leaves of mangrove plant Rhizophora stylosa Griff. Structural elucidation of the metabolites was carried out by analysis of their spectroscopic data and by comparison with those reported in the literature. All these compounds exhibited antimicrobial activity and were isolated from this genus for the first time

Five lignans from the mangrove Rhizophora stylosa Griff.

Five lignans (-)-(7R,8S)-dihydrodehydrodiconiferyl alcohol (1), (7S,8R)-3,3¢,5-trimethoxy-4¢,7-epoxy-8,5¢-neolignan-4,9,9¢-triol (2), (+)-isolariciresinol (3), polystachyol (4), (+)-pinoresinol (5) were isolated from the mangrove plant Rhizophora stylosa Griff.. The chemical structures of these compounds were elucidated by analysis of their NMR spectra and compared with those reported references. All these compounds were isolated from this plant for the first time

Silychristin and isosilychristin from the fruits of Silybum marianum (L.) Gaertin

By various chromatography methods, two flavonolignan silychristin (1) and isosilychristin (2)were isolated from the fruits of Silybum marianum (L.) Gaertn. cultivated in the North of Vietnam. Their structures were elucidated by analyses of the NMR (1D-, 2D-NMR) and ESI spectra. This is the first report of both 1 and 2 from S. marianum cultivated in Vietnam

Pinoresinol and 3,4',5,7-tetrahydroxy-3'-methoxyflavanone from the fruits of Silybum marianum (L.) Gaertn

From the fruits of Silybum marianum (L.) Gaertn. cultivated in the North of Vietnam, (±)2,6-bis(4′-hydroxy-3′-methoxy-phenyl)-3,7-dioxabicyclo[3.3.0]octane (pinoresinol) (1) and 3,4′,5,7-tetrahydroxy-3′-methoxyflavanone (2) were isolated. Their structures were elucidated by analyses of the NMR and mass spectra in comparison with the reported data. This is the first report of both 1 and 2 from Silybum species

GLUCOSIDES AND UREA DERIVATIVES FROM THE SEEDS OF SCAPHIUM MACROPODUM (MIQ.) BEUMÉE

Five known compounds {carbonylbis[imino(6-methyl-3,1-phenylenel)]}bis[carbamic acid] dimethyl ester (1), (1'R,3'S,5'R,8'S,2E,4E-dihydrophaseic acid) 3'-O-beta-D-glucopyranoside (2), 3-methylbutan-1-ol beta-D-glucopyranoside (3), astragalin (4) and daucosterol (5) were isolated from the methanol extract of the seeds of Scaphium macropodum (Miq.) Beumée. The structures of the isolated compounds were elucidated by the spectroscopic methods including NMR and MS, and also by comparison with the literature data. Compounds 1-3 were isolated from this plant for the first time

TWEAK-FN14 signaling induces lysosomal degradation of a cIAP1–TRAF2 complex to sensitize tumor cells to TNFα

Synthetic inhibitor of apoptosis (IAP) antagonists induce degradation of IAP proteins such as cellular IAP1 (cIAP1), activate nuclear factor κB (NF-κB) signaling, and sensitize cells to tumor necrosis factor α (TNFα). The physiological relevance of these discoveries to cIAP1 function remains undetermined. We show that upon ligand binding, the TNF superfamily receptor FN14 recruits a cIAP1–Tnf receptor-associated factor 2 (TRAF2) complex. Unlike IAP antagonists that cause rapid proteasomal degradation of cIAP1, signaling by FN14 promotes the lysosomal degradation of cIAP1–TRAF2 in a cIAP1-dependent manner. TNF-like weak inducer of apoptosis (TWEAK)/FN14 signaling nevertheless promotes the same noncanonical NF-κB signaling elicited by IAP antagonists and, in sensitive cells, the same autocrine TNFα-induced death occurs. TWEAK-induced loss of the cIAP1–TRAF2 complex sensitizes immortalized and minimally passaged tumor cells to TNFα-induced death, whereas primary cells remain resistant. Conversely, cIAP1–TRAF2 complex overexpression limits FN14 signaling and protects tumor cells from TWEAK-induced TNFα sensitization. Lysosomal degradation of cIAP1–TRAF2 by TWEAK/FN14 therefore critically alters the balance of life/death signals emanating from TNF-R1 in immortalized cells

Studying Magnetic Fields and Dust in M17 Using Polarized Thermal Dust Emission Observed by SOFIA/HAWC

We report on the highest spatial resolution measurement to date of magnetic fields (B-fields) in M17 using thermal dust polarization measurements taken by SOFIA/HAWC+ centered at a wavelength of 154 μm. Using the Davis–Chandrasekhar–Fermi method, in which the polarization angle dispersion calculated using the structure function technique is the quantity directly observed by SOFIA/HAWC+, we found the presence of strong B-fields of 980 ± 230 and 1665 ± 885 μG in the lower-density M17-N and higher-density M17-S regions, respectively. The B-field morphology in M17-N possibly mimics the fields in gravitationally collapsing molecular cores, while in M17-S the fields run perpendicular to the density structure. M17-S also displays a pillar feature and an asymmetric large-scale hourglass-shaped field. We use the mean B-field strengths to determine Alfvénic Mach numbers for both regions, finding that B-fields dominate over turbulence. We calculate the mass-to-flux ratio, λ, finding λ = 0.07 for M17-N and 0.28 for M17-S. These subcritical λ values are consistent with the lack of massive stars formed in M17. To study dust physics, we analyze the relationship between dust polarization fraction, p, emission intensity, I, gas column density, N(H2), polarization angle dispersion function, S, and dust temperature, T d. p decreases with intensity as I −α with α = 0.51. p tends to first increase with T d, but then decreases at higher T d. The latter feature, seen in M17-N at high T d when N(H2) and S decrease, is evidence of the radiative torque disruption effect

A polyhydroxylated sterol and a saponin isolated from the starfish culcita novaeguineae

Using various chromatographic methods, a polyhydroxylated sterol 5α-cholestane-3β,6β,7α,8β,15α,16β,26-heptol (1) and an asterosaponin sodium salt of 6α-[(O-β-D-fucopyranosyl-(l®2)-O-β-D-galactopyranosyl-(l®4)-O-[β-D-quinovopyranosyl-(l®2)]-O-β-D-xylopyranosyl-(l®3)-O-β-D-quinovopyranosyl)oxy]-5α-pregn-9(11)-ene-20-one (2), were isolated from the methanol extract of the starfish Culcita novaeguineae. Their structures were elucidated by 1D and 2D-NMR experiments and comparison of their NMR data with reported values. Compounds 1 was isolated from         C. novaeguineae for the first time