Objective:To compare embryonic development,ploidy status and clinical outcomes between fresh and frozen-thawed oocytes.Methods:This retrospective cohort study evaluated 83 fertilization cycles including both fresh and...Objective:To compare embryonic development,ploidy status and clinical outcomes between fresh and frozen-thawed oocytes.Methods:This retrospective cohort study evaluated 83 fertilization cycles including both fresh and frozen oocytes from 79 patients at the HP Fertility Center of Hai Phong International Hospital of Obstetrics and Pediatrics in Vietnam.The patient underwent several ovarian stimulation cycles to accumulate a certain number of oocytes that would be vitrified.In the last oocyte retrieval,all patient’s oocytes including both frozen and fresh would be fertilized.The outcomes included the rates of oocyte survival,cleavage embryo,blastocyst,ploidy status,pregnancy,biochemical pregnancy and clinical pregnancy.Results:The oocyte survival rate after thawing was 96.5%.No statistically significant difference was found when comparing fresh and frozen oocytes regarding fertilization rate(78.1%vs.75.5%,P=0.461),usable cleavage embryo rate(86.9%vs.87.2%,P=0.916)but usable blastocyst rate was found higher statistically in the frozen oocyte group(44.4%vs.54.0%,P=0.049).The percentages of euploid,aneuploid and mosaic embryos between the fresh group and the vitrified group had no significant differences(33.8%vs.31.6%,P=0.682;51.0%vs.54.2%,P=0.569;15.2%vs.12.4%,P=0.787;respectively).The rates of pregnancy,biochemical pregnancy and clinical pregnancy had no statistical difference(68.8%vs.64.8%,P=0.764;12.5%vs.3.6%,P=0.258;37.5%vs.46.4%,P=0.565).17 Mature oocytes are the minimum to have at least one euploid embryo.Conclusions:Oocyte vitrification does not affect embryonic,genetic and clinical results.The number of mature oocytes should be considered for fertilization in some cases.展开更多
Brandisia is a shrubby genus of about eight species distributed basically in East Asian evergreen broadleaved forests(EBLFs),with distribution centers in the karst regions of Yunnan,Guizhou,and Guangxi in southwestern...Brandisia is a shrubby genus of about eight species distributed basically in East Asian evergreen broadleaved forests(EBLFs),with distribution centers in the karst regions of Yunnan,Guizhou,and Guangxi in southwestern China.Based on the hemiparasitic and more or less liana habits of this genus,we hypothesized that its evolution and distribution were shaped by the development of EBLFs there.To test our hypothesis,the most comprehensive phylogenies of Brandisia hitherto were constructed based on plastome and nuclear loci(nrDNA,PHYA and PHYB);then divergence time and ancestral areas were inferred using the combined nuclear loci dataset.Phylogenetic analyses reconfirmed that Brandisia is a member of Orobanchaceae,with unstable placements caused by nuclear-plastid incongruences.Within Brandisia,three major clades were well supported,corresponding to the three subgenera based on morphology.Brandisia was inferred to have originated in the early Oligocene(32.69 Mya)in the Eastern Himalayas-SW China,followed by diversification in the early Miocene(19.45 Mya)in karst EBLFs.The differentiation dates of Brandisia were consistent with the origin of keystone species of EBLFs in this region(e.g.,Fagaceae,Lauraceae,Theaceae,and Magnoliaceae)and the colonization of other characteristic groups(e.g.,Gesneriaceae and Mahonia).These findings indicate that the distribution and evolution of Brandisia were facilitated by the rise of the karst EBLFs in East Asia.In addition,the woody and parasitic habits,and pollination characteristics of Brandisia may also be the important factors affecting its speciation and dispersal.展开更多
The environmental impact of coastal sand mining activities in Hai Phong city was assessed using ten proposed sustainable criteria for socio-economic development,and ecological and environmental protection.These ten cr...The environmental impact of coastal sand mining activities in Hai Phong city was assessed using ten proposed sustainable criteria for socio-economic development,and ecological and environmental protection.These ten criteria were developed by the analysis of the Dynamics-Pressure-State-Impact-Response(DPSIR)framework,including one driver and pressure criterion(D and P),seven status and impact criteria(S and I),and two response criteria(R).Each criterion is quantified according to five specific evaluation criteria corresponding to the evaluation score from 1 to 5.The results of the ten criterion application for environmental impact assessment of coastal mining Hai Phong by weighting show that the areas with economic activities,benthic biodiversity,and coastal ecosystems are most negatively impacted(score 4/5 and 3.5/5).Other subjects suffer low to moderate impacts(score 1/5 to 3/5).The environmental impact of sand mining(2015-2020)is generally moderate(score ranging from 2/5 to 3/5).The set of adjusted criteria can be applied to similar activities in coastal provinces and cities in Vietnam.展开更多
Seagrass beds degraded significantly since the last century on both, global and local scale. The seagrass species Enhalus acoroides(Linnaeus f.) Royle is a common species found in almost all marine ecosystems includin...Seagrass beds degraded significantly since the last century on both, global and local scale. The seagrass species Enhalus acoroides(Linnaeus f.) Royle is a common species found in almost all marine ecosystems including bays,lagoons and around offshore islands in tropical regions of the West Pacific. It was shown that genetic diversity is an essential indicator of the conditions of ecosystems. In the present study, microsatellite markers were used to assess the genetic diversity and population structure of six distinct seagrass beds along the coast of the Khanh Hoa Province, Vietnam. The results indicate that the genetic diversity of the populations in the open sea is higher than in the lagoon. Seagrass beds occurring in disturbed sites show reduced genetic diversity. The fixing index value(FST) depicts a relatively high genetic structure among populations. Structure analysis clusters the populations into open sea and lagoon populations and cluster analysis and AMOVA indicate a significant difference between the two groups. There are low but non-significant positive correlations between geographic and genetic distances.The different habitats of the open sea and the lagoon are probably responsible for forming two groups.展开更多
Objective:To investigate the osteoblastogenic activity of the ethyl acetate(EtOAc)extract of Smilax glabra Roxb roots and its major active compound astilbin.Methods:Astilbin was isolated from EtOAc extract using silic...Objective:To investigate the osteoblastogenic activity of the ethyl acetate(EtOAc)extract of Smilax glabra Roxb roots and its major active compound astilbin.Methods:Astilbin was isolated from EtOAc extract using silica gel chromatography combined with fraction crystallization.Chemical structure of astilbin was determined by analysis of the spectroscopic data in comparison with the literature.MTT method was used to detect the toxicity.Alkaline phosphatase(ALP)activity was determined by the spectrophotometric method at 405 nm using p-nitrophenyl phosphate as a substrate.Calcium deposition was stained with alizarin red-S,distained with cetylpyridium chloride,and quantified at 562 nm.In silico model for astilbin-ALP interaction was analyzed using AutoDock 4.2.6.The changes in expression of osteoblast differentiation related genes were determined using quantitative real-time PCR.Results:Both the EtOAc extract and astilbin had no toxicity toward osteoblast MC3T3-E1 cells at 5.0,10,25,and 50μg/mL.At 25μg/mL,they enhanced ALP activity and mineralization of osteoblasts up to 30%and 55%for the EtOAc extract and 22%and 41%for astilbin,respectively.Molecular docking analysis of astilbin-ALP interaction revealed Arg167,Asp320,His324,and His437 were key residues participating in hydrophobic interaction;meanwhile,His434 and Thr436 residues were involved in hydrogen bond formation in the active site of human tissue-nonspecific ALP.Moreover,the expression level of genes opn,col1,osx,and runx2 were up-regulated in astilbin treated samples with the fold changes as 2.2;3.7;4.1;2.3,respectively at 10μg/mL(P<0.05).Conclusions:The EtOAc extract and its major compound astilbin exhibit osteoblastogenic activity by up-regulating important markers for bone cell differentiation.It could be a new and promising osteogenic agent with dual actions for therapeutic applications.展开更多
The combustiondynamic experiments of blend-melt samples of blending pulverized coal and waste plastic are carried out in different proportions at different combustion temperatures.The experiment shows that all of corr...The combustiondynamic experiments of blend-melt samples of blending pulverized coal and waste plastic are carried out in different proportions at different combustion temperatures.The experiment shows that all of correlation coefficients for fitting straight lines of curve F(a)-1/T of the blend-melt samples are above 0.95,which indicates that the combustion of samples conforms to the rules of first order reaction.The experiment also shows that the activation energy is the lowest and the combustion becomes easier with the mix proportion of 20%-25% at 200 ℃.展开更多
In this paper, compounds identified in the essential oils obtained by hydrodistillation of the leaves of Cinnamomum glaucescens (Nees) Hand.-Mazz and Cinnamomum verum J.S. Presl (Lauraceae family) of Vietnam origin ar...In this paper, compounds identified in the essential oils obtained by hydrodistillation of the leaves of Cinnamomum glaucescens (Nees) Hand.-Mazz and Cinnamomum verum J.S. Presl (Lauraceae family) of Vietnam origin are reported. The chemical analyses were performed using gas chromatography-flame ionisation detector (GC-FID) and gas chromatography coupled with mass spectrometry (GC-MS). The significant compounds of C. glaucescens were geraniol (36.2%) and terpinen-4-ol (19.7%). On the other hand, C. verum comprised of linalool (22.0%) and bicyclogermacrene (11.2%). The present results may represent new chemotypes of the essential oils of C. verum and C. glaucescens.展开更多
Derivation of more sensitive spectral features from the satellite data is immensely important for better retrieving land cover information and change monitoring, such as changes in snow covered area, forests, and barr...Derivation of more sensitive spectral features from the satellite data is immensely important for better retrieving land cover information and change monitoring, such as changes in snow covered area, forests, and barren lands as some examples from local to the global scale. The major objectives of this paper are to present the potential of water-resistant snow index (WSI) for the detection of snow cover changes in the Himalayas, extant two composite images, biophysical image composite (BIC) and forest cover composite (FCC) for the detection of changes in barren lands and forested areas respectively, and two newly designed composite images, water cover composite (WCC) and urban cover composite (UCC) for the detection of changes in water and urban areas respectively. This research implemented the image compositing technique for the detection and visualization of land cover changes (water, forest, barren, and urban) with respect to local administrative areas where a significant land cover change occurred from 2001 to 2016. A case study was also conducted in the Himalayan region to identify snow cover changes from 2001 to 2015 using the WSI. Analysis of the annual variation of the snow cover in the Himalayas indicated a decreasing trend of the snow cover. Consequently, the downstream areas are more likely to suffer from snow related hazards such as glacial outbursts, avalanches, landslides and floods. The changes in snow cover in the Himalayas may bring significant hydrophysical and livelihood changes in the downstream area including the Mekong Delta. Therefore, the countries sharing the Himalayan region should focus on adapting the severe impacts of snow cover changes. The image compositing approach presented in the research demonstrated promising performance for the detection and visualization of other land cover changes as well.展开更多
The Indochinese Peninsula, which contains two thirds of the world’s tropical forests, however, is one of the world’s most threatened habitat with some of the highest rates of deforestation and land use changes. Avai...The Indochinese Peninsula, which contains two thirds of the world’s tropical forests, however, is one of the world’s most threatened habitat with some of the highest rates of deforestation and land use changes. Availability of higher resolution satellite data collected by the likes of Landsat 8 and Sentinel-1-2 has brought new opportunities for precise land cover monitoring in recent years. However, utilizing a massive volume of high spatial and temporal resolution data for ecological applications is challenging. One approach is to employ composite images generated from the multi-temporal satellite data. The research was conducted in two study sites located in the Indochinese Peninsula, Laos-Thailand and Vietnam-Cambodia, vulnerable to deforestation and land use changes. We assessed the potential of recently available composite images, such as Biophysical Image Composite (BIC), Forest Cover Composite (FCC), Enhanced Forest Cover Composite (EFCC), and Water Cover Composite (WCC) for the classification and mapping of land cover types. Three machine learning classifiers, k-Nearest Neighbors (KNN), Support Vector Machines (SVM) and Random Forests (RF) were employed and the performance of composite images was evaluated quantitatively with the support of ground truth data. The overall accuracies (Kappa coefficient) obtained from the combination of composite images were 0.92 (0.89) and 0.90 (0.86) for Laos-Thailand, and Vietnam sites respectively. These results highlight effectiveness of the composite images for the classification and mapping of land cover types.展开更多
ENSO(El Niño-Southern Oscillation)phenomena have impacted on the hydrodynamic regime and environmental factors of the tropical ocean in general.In case of Vietnamese South-Central Waters,impacts of ENSO only focu...ENSO(El Niño-Southern Oscillation)phenomena have impacted on the hydrodynamic regime and environmental factors of the tropical ocean in general.In case of Vietnamese South-Central Waters,impacts of ENSO only focused on issues of changing seasonal wind,seawater temperature anomalies,changing of water masses as the air-sea interaction.Based on several data sets collecting in the period of 2003-2017,new finding of seawater temperature,salinity and environmental factors was identified in the water masses of Vietnamese South-Central Waters.The highest salinity was 35.4‰.During the El Nino event,increasing water temperature and salinity caused to move the deeper water masses to be closer to the sea surface than that initial depth in the neutral period.During the La Nina event,the temperature of most water masses reduced by 0.1-3.0℃,and then these water masses could be affected to the deeper layer.During the phase from strong ENSO event towards the neutral time,nutrient salts of the 4 water masses were lower concentration in the neutral year,causing the lack of phosphorus in sea surface water masses.展开更多
Objective: To isolate a-mangostin(AMG) from the peels of mangosteen(Garcinia mangostana L.), grown in Vietnam, and to investigate antibiofilm activity of this compound against three Staphylococcus aureus(S. aureus) st...Objective: To isolate a-mangostin(AMG) from the peels of mangosteen(Garcinia mangostana L.), grown in Vietnam, and to investigate antibiofilm activity of this compound against three Staphylococcus aureus(S. aureus) strains, one of which was methicillin-resistant S. aureus(MRSA) and the other two strains were methicillinsensitive S. aureus(MSSA).Methods: AMG in n-hexane fraction was isolated on a silica gel column and chemically analyzed by HPLC and NMR. The antibiofilm activity of this compound was investigated by using a 96-well plate model for the formation of biofilms. Biofilm biomass was quantified using crystal violet. The viability of cells was observed under confocal microscopy using LIVE/DEAD Bac Light stains. Biofilm composition was determined using specific chemical and enzyme tests for polysaccharide, protein and DNA. Membranedamaging activity was assayed by measuring the hemolysis of human red blood cells in presence of AMG.Results: The results indicated that the isolated AMG, with a purity that exceeded 98%,had minimal inhibitory concentrations in the range of 4.6–9.2 mmol/L for the three strains tested. Interestingly, the MSSA strains were more sensitive to AMG than the MRSA strain. Minimal bactericidal concentrations were 2-fold higher than the minimal inhibitory concentration values for the three strains, indicating that AMG was a bactericidal compound. AMG also prevented biofilm formation effectively, albeit that again the MRSA strain was the most resistant. Interestingly, biofilms of the MRSA strain contained protein as a main component of the extracellular matrix, whereas this was polysaccharide in the MSSA strains. This might relate to the resistance of the MRSA 252 strain to AMG.Assays using human red blood cells indicated that AMG caused significant membrane damage with 50% of cell lysis occurred at concentration of about 36 mmol/L.Conclusions: Our results provide evidence that the isolated AMG has inhibitory activity against biofilm formation by S. aureus, including MRSA. Thus, isolated AMG proposes a high potential to develop a novel phytopharmaceutical for the treatment of MRSA.展开更多
The single prefrontal configuration has historically been used as an important diagnostic character for many natricine taxa. For example, the genus Trimerodytes Cope, 1895 was long been regarded as a junior synonym of...The single prefrontal configuration has historically been used as an important diagnostic character for many natricine taxa. For example, the genus Trimerodytes Cope, 1895 was long been regarded as a junior synonym of Opisthotropis Günther, 1872 for their similar prefrontal configurations and the type species, T. balteatus Cope, 1895, has been assigned to the genus Opisthotropis. However, as the number and arrangement of prefrontal vary frequently both at species and generic level, it is questionable whether the synonymization of Trimerodytes reflects their evolutionary relationships. On the basis of recently collected specimens of O. balteata, the generic status of the species was assessed using both molecular and morphological data. Opisthotropis was recovered as polyphyletic with reference to O. balteata, because O. balteata is nested within the genus Sinonatrix Rossman and Eberle, 1977 and is the sister species of the type species of Sinonatrix. Consequently, we herein resurrect the long-overlooked synonym Trimerodytes from Opisthotropis and synonymize the junior generic nomen Sinonatrix with Trimerodytes. In addition, based on morphological similarities between the monotypic genus Paratapinophis Angel, 1929 and Trimerodytes, we doubt about the validity of Paratapinophis. Following taxonomic changes in this work, the taxonomic account of the genus Trimerodytes, updated descriptions of its type species, and diagnostic key to Trimerodytes species are provided.展开更多
We describe a new species of Rhacophorus based on two adult specimens collected from Hoa Binh Province, northern Vietnam. Rhacophorus hoabinhensis sp. nov. is distinguishable from its congeners on the basis of a combi...We describe a new species of Rhacophorus based on two adult specimens collected from Hoa Binh Province, northern Vietnam. Rhacophorus hoabinhensis sp. nov. is distinguishable from its congeners on the basis of a combination of the following morphological characters: size small(SVL 31.1–32.5 mm in males); head slightly longer than wide; vomerine teeth absent; snout short(SNL/SVL 0.16); dorsal skin smooth; forearm and tarsus with dermal fringes; dermal appendage at vent present; webbing formula on fingers Ⅰ12/3-12/3 Ⅱ1-2 Ⅲ1-1 Ⅳ and on toes Ⅰ3/4-1 Ⅱ1/2-1Ⅲ1/2-1 Ⅳ1-1/2Ⅳ; dorsal surface grey yellow with brown spots; lower jaw region dark grey, throat, chest and belly cream; anterior and posterior thighs, as well as ventral surface of tibia orange. The interspecific uncorrected genetic distances(16 S rRNA gene) between the new species from Hoa Binh and other analyzed congeners varied from 9.8% to 17.4%. In the phylogenetic analyses, the new species revealed to be a representative of Rhacophorus and was nested within the R. hoanglienensis-orlovi species group.展开更多
Objective:To investigate the antibiofilm activity of alphamangostin(AMG)loaded nanoparticle(nano AMG)against dental caries pathogen Streptococcus mutans.Methods:AMG was isolated from the peels of Garcinia mangostana L...Objective:To investigate the antibiofilm activity of alphamangostin(AMG)loaded nanoparticle(nano AMG)against dental caries pathogen Streptococcus mutans.Methods:AMG was isolated from the peels of Garcinia mangostana L.using silica gel columns and chemically analysed by high performance liquid chromatography and nuclear magnetic resonance.Nano AMG was prepared using the solvent evaporation method combined with high-speed homogenization.The nanoparticles were characterized using dynamic light scattering,field emission scanning electron microscopy(FE-SEM)and Fourier transform infrared spectroscopy(FTIR).The toxicity of nano AMG in fibroblast NIH/3 T3 cell line was determined using MTT method.The antibiofilm effect of nano AMG was determined through the evaluation of biofilm formation by Streptococcus mutans using a 96-well plate.Biofilm biomass was quantified using crystal violet.Cell viability was observed under confocal microscopy using LIVE/DEAD Bac Light staining.Moreover,gene expression was determined by quantitative real-time PCR and membrane permeabilization activity by measuring the uptake of o-nitrophenol-β-D-galactoside.Results:Nano AMG size was in a range of 10-50 nm with a polydispersity index of<0.3 and zeta potential value of-35.2 m V.The size and the incorporation of AMG in the nanoparticles were confirmed by FE-SEM and FTIR analyses.The IC50 values of the test agents on NIH/3 T3 cells were(9.80±0.63)μg/m L for AMG and(8.70±0.81)μg/m L for nano AMG,while no toxicity was generated from excipients used to prepare nanoparticles.In the early stage of biofilm formation,treatment with 6.25μmol/L nano AMG caused a reduction in biofilm biomass up to 49.1%,compared to 33.4%for AMG.In contrast,biofilms at the late stage were more resistant to the test agents.At 96μmol/L(=10×MIC),nano AMG reduced only 20.7%of biofilm biomass while AMG did not showany effect.Expressions of gtf B and gtf C genes involved in biofilm formation were down-regulated 3.3 and 12.5 folds,respectively,compared to AMG(2.4 and 7.6 folds,respectively).LIVE/DEAD Bac Light fluorescence staining and microscopy observation indicated that biofilm cells were killed by both nano AMG and AMG at 48μmol/L(=5×MIC).In addition,membrane permeabilization activity was increased in a time dependent manner and higher in nano AMG treated cells compared to AMG.Conclusions:AMG coated nanoparticle can enhance AMG bioactivity and can be used as a new and promising antibiofilm agent.展开更多
We describe a new species of megophryid frog from Phu Yen Province in southern Vietnam. Leptolalax macrops sp. nov. is distinguished from its congeners by a combination of the following morphological attributes:(1) bo...We describe a new species of megophryid frog from Phu Yen Province in southern Vietnam. Leptolalax macrops sp. nov. is distinguished from its congeners by a combination of the following morphological attributes:(1) body size medium(SVL 28.0–29.3 mm in three adult males, 30.3 mm in single adult female);(2) supra-axillary glands present, creamy white; ventrolateral glands indistinct;(3) tympanum externally distinct;(4) dorsal skin roughly granular with larger tubercles, dermal ridges on dorsum absent;(5) rudimentary webbing present between fingers Ⅰ–Ⅱ and Ⅱ–Ⅲ; rudimentary webbing between all toes; fingers and toes without dermal fringes;(6) in life ventral surface greyish-violet with white speckling;(7) supratympanic fold distinct, dark brown in life;(8) iris bicolored, typically golden in upper half, fading to golden green in lower half;(9) tibia short(TbL/SVL 0.44–0.45 in males); and(10) eyes large and protuberant(ED/SVL 0.15–0.16 in males).From all congeners for which comparable sequences are available, the new species differs markedly in the 16 S rRNA mitochondrial gene sequence(P-distance>5.7%). The new species is currently known only from montane evergreen tropical forests of Song Hinh District, Phu Yen Province, and M'Drak District of Dak Lak Province at elevations of 470–630 m a.s.l.. We suggest the new species should be considered as Data Deficient following the IUCN's Red List categories. We also report a previously unknown Leptolalax mt DNA lineage from an evergreen tropical forest in the Hoa Thinh District of Phu Yen Province,which may also represent an undescribed species.展开更多
Atacama Large Millimetre/sub-millimetre Array(ALMA) observations of CO(1–0) and CO(2–1) emissions from the circumstellar envelope of the asymptotic giant branch(AGB) star EP Aqr have been made with four times better...Atacama Large Millimetre/sub-millimetre Array(ALMA) observations of CO(1–0) and CO(2–1) emissions from the circumstellar envelope of the asymptotic giant branch(AGB) star EP Aqr have been made with four times better spatial resolution than previously available. They are analysed with emphasis on the de-projection in space of the effective emissivity and flux of matter using as input a prescribed configuration of the velocity field, assumed to be radial. The data are found to display an intrinsic axisymmetry with respect to an axis making a small angle with respect to the line of sight. A broad range of wind configurations, from prolate(bipolar) to oblate(equatorial) has been studied and found to be accompanied by significant equatorial emission. Qualitatively, the effective emissivity is enhanced near the equator to produce the central narrow component observed in the Doppler velocity spectra and its dependence on star latitude generally follows that of the wind velocity with the exception of an omni-present depression near the poles. In particular, large equatorial expansion velocities produce a flared disc or a ring of effective emissivity and mass loss. The effect on the determination of the orientation of the star axis of radial velocity gradients, and possibly competing rotation and expansion in the equatorial disc, is discussed. In general,the flux of matter is found to reach a broad maximum at distances of the order of 500 AU from the star.Arguments are given that may be used to favour one wind velocity distribution over another. As a result of the improved quality of the data, a deeper understanding of the constraints imposed on morphology and kinematics has been obtained.展开更多
Observations by the Atacama Large Millimetre/sub-millimetre Array of the dust continuum and13 CO(3–2) millimetre emissions of the triple stellar system GG Tau A are analysed,giving evidence for a rotating gas disc an...Observations by the Atacama Large Millimetre/sub-millimetre Array of the dust continuum and13 CO(3–2) millimetre emissions of the triple stellar system GG Tau A are analysed,giving evidence for a rotating gas disc and a concentric and coplanar dust ring. The present work complements an earlier analysis(Tang et al.) by exploring detailed properties of the gas disc. A 95% confidence level upper limit of 0.24′′(34 au) is placed on the disc scale height at a distance of 1′′(140 au) from the central stars. Evidence for Keplerian rotation of the gas disc is presented,with the rotation velocity reaching^3.1 km s^(-1) at 1′′ from the central stars,and a 99% confidence level upper limit of 9% is placed on relative contribution from a possible in-fall velocity. Variations of the intensity across the disc area are studied in detail and confirm the presence of a hot spot in the south-eastern quadrant. However several other significant intensity variations,in particular a depression in the northern direction,are also revealed. Variations of the intensity are found to be positively correlated to variations of the line width. Possible contributions to the measured line width are reviewed,suggesting an increase of the disc temperature and opacity with decreasing distance from the stars.展开更多
A new species Lobophora tsengii is described from Bach Long Vy(Bailongwei)Island,Haiphong Province,Vietnam.The plants inhabit the subtidal zone and have predominantly erect fan-shaped thalli that attach to the substra...A new species Lobophora tsengii is described from Bach Long Vy(Bailongwei)Island,Haiphong Province,Vietnam.The plants inhabit the subtidal zone and have predominantly erect fan-shaped thalli that attach to the substrate by a basal holdfast.The thallus is commonly composed of a single layer of large medullary cells with four layers of cortical cells on either side of the medulla.The newly collected specimens from the island are morphologically similar to those from Hainan Island,China,but differ from the New Caledonian ones in having thicker thallus.In molecular phylogenetic analyses based on concatenated rbcL and cox3 s equences,the specimens from the island were 100%identical to those from Hainan Island,China,and they formed a clade separating from other Lobophora species.Additionally,based on analyses of numerous cox3 s equences,our specimens were also distinguished from the closely related taxa occurring in New Caledonia,Kenya,and West Australia.Combining the morphological and molecular analyses,we conclude that our specimens represent a new species of Lobophora,which is apparently endemic to the Beibu Gulf(Gulf of Tonkin)and adjacent waters.展开更多
To study the heating mechanism of electron cyclotron resonance thruster(ECRT)immersed in a non-uniform magnetic field,experiments and simulations are performed based on an electron cyclotron resonance plasma source at...To study the heating mechanism of electron cyclotron resonance thruster(ECRT)immersed in a non-uniform magnetic field,experiments and simulations are performed based on an electron cyclotron resonance plasma source at ASIPP.It is found that the first harmonic of electron cyclotron resonance is essential for plasma ignition at high magnetic field(0.0875 T),while the plasma can sustain without the first and second harmonics of electron cyclotron resonance at low magnetic field(till 0.0170 T).Evidence of radial hollow density profile indicates that upper hybrid resonance,which has strong edge heating effect,is the heating mechanism of low-field ECRT.The heating mode transition from electron cyclotron resonance to upper hybrid resonance is also revealed.Interestingly,the evolutions of electron temperature and electron density with input power experience a‘delayed’jump,which may be correlated with the different power levels required for cyclotron and ionization.Moreover,when the field strength decreased,the variation of electron density behaves in an opposite trend with that of electron temperature,implying a possible competition of power deposition between them.The present work is of great interest for understanding the plasma discharge in ECRT especially immersed in a non-uniform magnetic field,and designing efficient ECRT using low magnetic field for economic space applications.展开更多
SW(Seaweed)is a valuable coastal resource for its use in food,cosmetics,medicine and other items.In this study,PS(PlanetScope)imagery was combined with field sampling to demonstrate the capability of mapping of SAV(Su...SW(Seaweed)is a valuable coastal resource for its use in food,cosmetics,medicine and other items.In this study,PS(PlanetScope)imagery was combined with field sampling to demonstrate the capability of mapping of SAV(Submerge Aquatic Vegetation)(including both SW and SG(Seagrass)beds)and biomass mapping of Sargassum meadows in An Chan coastal waters,Tuy An district,Phu Yen province,Vietnam.In term of SAV and Sargassum mapping,authors proposed an improved remote sensing technique based on Sagawa’s BRI(Bottom Reflectance Index)algorithm with attention to Tassan’s concept in discrimination of light attenuation coefficient Kd between shallow and deep waters.Authors’results showed high accuracy in mapping of SAV and Sargassum distribution with overall accuracy and Kappa coefficient of 92.52%and 0.8957,respectively.The classified class of SW(i.e.Sargassum sp.)then was separated absolutely from other classes in SAV map for estimation of Sargassum biomass.The red and green spectral pre-processed BRI channels(i.e.BRI3 and BRI2)of PS were used to estimate the Sargassum biomass using a multiple 2nd order polynomial regression model with very high accuracy(R2=0.9707;RMSE=±109.21 g/m2).The average total Sargassum biomass was 897.8 g/m2 with total Sargassum yield in whole region reaching a value of 449.57 tons in cover area of 50.32 ha of Sargassum meadows.This result opens the great potential of biomass and yield estimation of Sargassum and other SW meadows in coastal waters(including enough optically deep waters)by remote sensing techniques based on PS imagery.展开更多
文摘Objective:To compare embryonic development,ploidy status and clinical outcomes between fresh and frozen-thawed oocytes.Methods:This retrospective cohort study evaluated 83 fertilization cycles including both fresh and frozen oocytes from 79 patients at the HP Fertility Center of Hai Phong International Hospital of Obstetrics and Pediatrics in Vietnam.The patient underwent several ovarian stimulation cycles to accumulate a certain number of oocytes that would be vitrified.In the last oocyte retrieval,all patient’s oocytes including both frozen and fresh would be fertilized.The outcomes included the rates of oocyte survival,cleavage embryo,blastocyst,ploidy status,pregnancy,biochemical pregnancy and clinical pregnancy.Results:The oocyte survival rate after thawing was 96.5%.No statistically significant difference was found when comparing fresh and frozen oocytes regarding fertilization rate(78.1%vs.75.5%,P=0.461),usable cleavage embryo rate(86.9%vs.87.2%,P=0.916)but usable blastocyst rate was found higher statistically in the frozen oocyte group(44.4%vs.54.0%,P=0.049).The percentages of euploid,aneuploid and mosaic embryos between the fresh group and the vitrified group had no significant differences(33.8%vs.31.6%,P=0.682;51.0%vs.54.2%,P=0.569;15.2%vs.12.4%,P=0.787;respectively).The rates of pregnancy,biochemical pregnancy and clinical pregnancy had no statistical difference(68.8%vs.64.8%,P=0.764;12.5%vs.3.6%,P=0.258;37.5%vs.46.4%,P=0.565).17 Mature oocytes are the minimum to have at least one euploid embryo.Conclusions:Oocyte vitrification does not affect embryonic,genetic and clinical results.The number of mature oocytes should be considered for fertilization in some cases.
基金funded by the Key Projects of the Joint Fund of the National Natural Science Foundation of China(U1802232)the national youth talent support program+2 种基金CAS"Light of West China"ProgramYunnan youth talent support program(YNWR-QNBJ-2018-183 to Y.N.)Vietnam Academy of Science and Technology(UQDTCB.06/22-23)。
文摘Brandisia is a shrubby genus of about eight species distributed basically in East Asian evergreen broadleaved forests(EBLFs),with distribution centers in the karst regions of Yunnan,Guizhou,and Guangxi in southwestern China.Based on the hemiparasitic and more or less liana habits of this genus,we hypothesized that its evolution and distribution were shaped by the development of EBLFs there.To test our hypothesis,the most comprehensive phylogenies of Brandisia hitherto were constructed based on plastome and nuclear loci(nrDNA,PHYA and PHYB);then divergence time and ancestral areas were inferred using the combined nuclear loci dataset.Phylogenetic analyses reconfirmed that Brandisia is a member of Orobanchaceae,with unstable placements caused by nuclear-plastid incongruences.Within Brandisia,three major clades were well supported,corresponding to the three subgenera based on morphology.Brandisia was inferred to have originated in the early Oligocene(32.69 Mya)in the Eastern Himalayas-SW China,followed by diversification in the early Miocene(19.45 Mya)in karst EBLFs.The differentiation dates of Brandisia were consistent with the origin of keystone species of EBLFs in this region(e.g.,Fagaceae,Lauraceae,Theaceae,and Magnoliaceae)and the colonization of other characteristic groups(e.g.,Gesneriaceae and Mahonia).These findings indicate that the distribution and evolution of Brandisia were facilitated by the rise of the karst EBLFs in East Asia.In addition,the woody and parasitic habits,and pollination characteristics of Brandisia may also be the important factors affecting its speciation and dispersal.
基金support of the VAST project,code VAST05.06/22-23.
文摘The environmental impact of coastal sand mining activities in Hai Phong city was assessed using ten proposed sustainable criteria for socio-economic development,and ecological and environmental protection.These ten criteria were developed by the analysis of the Dynamics-Pressure-State-Impact-Response(DPSIR)framework,including one driver and pressure criterion(D and P),seven status and impact criteria(S and I),and two response criteria(R).Each criterion is quantified according to five specific evaluation criteria corresponding to the evaluation score from 1 to 5.The results of the ten criterion application for environmental impact assessment of coastal mining Hai Phong by weighting show that the areas with economic activities,benthic biodiversity,and coastal ecosystems are most negatively impacted(score 4/5 and 3.5/5).Other subjects suffer low to moderate impacts(score 1/5 to 3/5).The environmental impact of sand mining(2015-2020)is generally moderate(score ranging from 2/5 to 3/5).The set of adjusted criteria can be applied to similar activities in coastal provinces and cities in Vietnam.
基金The NAFOSTED under contract No.106-NN.02-2014.04the Umbrella of JSPS Core-to-core Program,B.Asia-Africa Science Platforms
文摘Seagrass beds degraded significantly since the last century on both, global and local scale. The seagrass species Enhalus acoroides(Linnaeus f.) Royle is a common species found in almost all marine ecosystems including bays,lagoons and around offshore islands in tropical regions of the West Pacific. It was shown that genetic diversity is an essential indicator of the conditions of ecosystems. In the present study, microsatellite markers were used to assess the genetic diversity and population structure of six distinct seagrass beds along the coast of the Khanh Hoa Province, Vietnam. The results indicate that the genetic diversity of the populations in the open sea is higher than in the lagoon. Seagrass beds occurring in disturbed sites show reduced genetic diversity. The fixing index value(FST) depicts a relatively high genetic structure among populations. Structure analysis clusters the populations into open sea and lagoon populations and cluster analysis and AMOVA indicate a significant difference between the two groups. There are low but non-significant positive correlations between geographic and genetic distances.The different habitats of the open sea and the lagoon are probably responsible for forming two groups.
基金supported by the the Vietnam Academy of Science and Technology under grant NCCC 08.10/20-20the Institute of Biotechnology under grant CS20-01。
文摘Objective:To investigate the osteoblastogenic activity of the ethyl acetate(EtOAc)extract of Smilax glabra Roxb roots and its major active compound astilbin.Methods:Astilbin was isolated from EtOAc extract using silica gel chromatography combined with fraction crystallization.Chemical structure of astilbin was determined by analysis of the spectroscopic data in comparison with the literature.MTT method was used to detect the toxicity.Alkaline phosphatase(ALP)activity was determined by the spectrophotometric method at 405 nm using p-nitrophenyl phosphate as a substrate.Calcium deposition was stained with alizarin red-S,distained with cetylpyridium chloride,and quantified at 562 nm.In silico model for astilbin-ALP interaction was analyzed using AutoDock 4.2.6.The changes in expression of osteoblast differentiation related genes were determined using quantitative real-time PCR.Results:Both the EtOAc extract and astilbin had no toxicity toward osteoblast MC3T3-E1 cells at 5.0,10,25,and 50μg/mL.At 25μg/mL,they enhanced ALP activity and mineralization of osteoblasts up to 30%and 55%for the EtOAc extract and 22%and 41%for astilbin,respectively.Molecular docking analysis of astilbin-ALP interaction revealed Arg167,Asp320,His324,and His437 were key residues participating in hydrophobic interaction;meanwhile,His434 and Thr436 residues were involved in hydrogen bond formation in the active site of human tissue-nonspecific ALP.Moreover,the expression level of genes opn,col1,osx,and runx2 were up-regulated in astilbin treated samples with the fold changes as 2.2;3.7;4.1;2.3,respectively at 10μg/mL(P<0.05).Conclusions:The EtOAc extract and its major compound astilbin exhibit osteoblastogenic activity by up-regulating important markers for bone cell differentiation.It could be a new and promising osteogenic agent with dual actions for therapeutic applications.
文摘The combustiondynamic experiments of blend-melt samples of blending pulverized coal and waste plastic are carried out in different proportions at different combustion temperatures.The experiment shows that all of correlation coefficients for fitting straight lines of curve F(a)-1/T of the blend-melt samples are above 0.95,which indicates that the combustion of samples conforms to the rules of first order reaction.The experiment also shows that the activation energy is the lowest and the combustion becomes easier with the mix proportion of 20%-25% at 200 ℃.
文摘In this paper, compounds identified in the essential oils obtained by hydrodistillation of the leaves of Cinnamomum glaucescens (Nees) Hand.-Mazz and Cinnamomum verum J.S. Presl (Lauraceae family) of Vietnam origin are reported. The chemical analyses were performed using gas chromatography-flame ionisation detector (GC-FID) and gas chromatography coupled with mass spectrometry (GC-MS). The significant compounds of C. glaucescens were geraniol (36.2%) and terpinen-4-ol (19.7%). On the other hand, C. verum comprised of linalool (22.0%) and bicyclogermacrene (11.2%). The present results may represent new chemotypes of the essential oils of C. verum and C. glaucescens.
文摘Derivation of more sensitive spectral features from the satellite data is immensely important for better retrieving land cover information and change monitoring, such as changes in snow covered area, forests, and barren lands as some examples from local to the global scale. The major objectives of this paper are to present the potential of water-resistant snow index (WSI) for the detection of snow cover changes in the Himalayas, extant two composite images, biophysical image composite (BIC) and forest cover composite (FCC) for the detection of changes in barren lands and forested areas respectively, and two newly designed composite images, water cover composite (WCC) and urban cover composite (UCC) for the detection of changes in water and urban areas respectively. This research implemented the image compositing technique for the detection and visualization of land cover changes (water, forest, barren, and urban) with respect to local administrative areas where a significant land cover change occurred from 2001 to 2016. A case study was also conducted in the Himalayan region to identify snow cover changes from 2001 to 2015 using the WSI. Analysis of the annual variation of the snow cover in the Himalayas indicated a decreasing trend of the snow cover. Consequently, the downstream areas are more likely to suffer from snow related hazards such as glacial outbursts, avalanches, landslides and floods. The changes in snow cover in the Himalayas may bring significant hydrophysical and livelihood changes in the downstream area including the Mekong Delta. Therefore, the countries sharing the Himalayan region should focus on adapting the severe impacts of snow cover changes. The image compositing approach presented in the research demonstrated promising performance for the detection and visualization of other land cover changes as well.
文摘The Indochinese Peninsula, which contains two thirds of the world’s tropical forests, however, is one of the world’s most threatened habitat with some of the highest rates of deforestation and land use changes. Availability of higher resolution satellite data collected by the likes of Landsat 8 and Sentinel-1-2 has brought new opportunities for precise land cover monitoring in recent years. However, utilizing a massive volume of high spatial and temporal resolution data for ecological applications is challenging. One approach is to employ composite images generated from the multi-temporal satellite data. The research was conducted in two study sites located in the Indochinese Peninsula, Laos-Thailand and Vietnam-Cambodia, vulnerable to deforestation and land use changes. We assessed the potential of recently available composite images, such as Biophysical Image Composite (BIC), Forest Cover Composite (FCC), Enhanced Forest Cover Composite (EFCC), and Water Cover Composite (WCC) for the classification and mapping of land cover types. Three machine learning classifiers, k-Nearest Neighbors (KNN), Support Vector Machines (SVM) and Random Forests (RF) were employed and the performance of composite images was evaluated quantitatively with the support of ground truth data. The overall accuracies (Kappa coefficient) obtained from the combination of composite images were 0.92 (0.89) and 0.90 (0.86) for Laos-Thailand, and Vietnam sites respectively. These results highlight effectiveness of the composite images for the classification and mapping of land cover types.
基金funded by projects of DTDL.CN.17/28,Institute of Oceanography projects in 2016-2017 and VTUD.12/18-20。
文摘ENSO(El Niño-Southern Oscillation)phenomena have impacted on the hydrodynamic regime and environmental factors of the tropical ocean in general.In case of Vietnamese South-Central Waters,impacts of ENSO only focused on issues of changing seasonal wind,seawater temperature anomalies,changing of water masses as the air-sea interaction.Based on several data sets collecting in the period of 2003-2017,new finding of seawater temperature,salinity and environmental factors was identified in the water masses of Vietnamese South-Central Waters.The highest salinity was 35.4‰.During the El Nino event,increasing water temperature and salinity caused to move the deeper water masses to be closer to the sea surface than that initial depth in the neutral period.During the La Nina event,the temperature of most water masses reduced by 0.1-3.0℃,and then these water masses could be affected to the deeper layer.During the phase from strong ENSO event towards the neutral time,nutrient salts of the 4 water masses were lower concentration in the neutral year,causing the lack of phosphorus in sea surface water masses.
基金Supported by the TWAS research grant 14-062 RG/BIO/AS_GNAFOSTED grant 106-NN.02–2016.19National Research Council of Thailand(NRCT)and Center of Excellence for Innovation in Chemistry(PERCH-CIC)
文摘Objective: To isolate a-mangostin(AMG) from the peels of mangosteen(Garcinia mangostana L.), grown in Vietnam, and to investigate antibiofilm activity of this compound against three Staphylococcus aureus(S. aureus) strains, one of which was methicillin-resistant S. aureus(MRSA) and the other two strains were methicillinsensitive S. aureus(MSSA).Methods: AMG in n-hexane fraction was isolated on a silica gel column and chemically analyzed by HPLC and NMR. The antibiofilm activity of this compound was investigated by using a 96-well plate model for the formation of biofilms. Biofilm biomass was quantified using crystal violet. The viability of cells was observed under confocal microscopy using LIVE/DEAD Bac Light stains. Biofilm composition was determined using specific chemical and enzyme tests for polysaccharide, protein and DNA. Membranedamaging activity was assayed by measuring the hemolysis of human red blood cells in presence of AMG.Results: The results indicated that the isolated AMG, with a purity that exceeded 98%,had minimal inhibitory concentrations in the range of 4.6–9.2 mmol/L for the three strains tested. Interestingly, the MSSA strains were more sensitive to AMG than the MRSA strain. Minimal bactericidal concentrations were 2-fold higher than the minimal inhibitory concentration values for the three strains, indicating that AMG was a bactericidal compound. AMG also prevented biofilm formation effectively, albeit that again the MRSA strain was the most resistant. Interestingly, biofilms of the MRSA strain contained protein as a main component of the extracellular matrix, whereas this was polysaccharide in the MSSA strains. This might relate to the resistance of the MRSA 252 strain to AMG.Assays using human red blood cells indicated that AMG caused significant membrane damage with 50% of cell lysis occurred at concentration of about 36 mmol/L.Conclusions: Our results provide evidence that the isolated AMG has inhibitory activity against biofilm formation by S. aureus, including MRSA. Thus, isolated AMG proposes a high potential to develop a novel phytopharmaceutical for the treatment of MRSA.
基金supported by the National Key Research and Development Program of China (2017YFC0505202)Strategic Priority Research Program of Chinese Academy of Sciences (XDB31000000)+6 种基金the National Natural Science Foundation of China (31722049, 31772434)Key Research Program of Frontier Sciences, CAS (QYZDB-SSW-SMC058)the Southeast Asia Biodiversity Research Institute, Chinese Academy of Science (Y4ZK111B01)the Youth Innovation Promotion Association of CASthe CAS “Light of West China” Program (2018XBZG_JCTD_001)Talent Program from Organization Department of Sichuan Provincial Committeepartially supported by project BSTMV.08/16-19 to NTT
文摘The single prefrontal configuration has historically been used as an important diagnostic character for many natricine taxa. For example, the genus Trimerodytes Cope, 1895 was long been regarded as a junior synonym of Opisthotropis Günther, 1872 for their similar prefrontal configurations and the type species, T. balteatus Cope, 1895, has been assigned to the genus Opisthotropis. However, as the number and arrangement of prefrontal vary frequently both at species and generic level, it is questionable whether the synonymization of Trimerodytes reflects their evolutionary relationships. On the basis of recently collected specimens of O. balteata, the generic status of the species was assessed using both molecular and morphological data. Opisthotropis was recovered as polyphyletic with reference to O. balteata, because O. balteata is nested within the genus Sinonatrix Rossman and Eberle, 1977 and is the sister species of the type species of Sinonatrix. Consequently, we herein resurrect the long-overlooked synonym Trimerodytes from Opisthotropis and synonymize the junior generic nomen Sinonatrix with Trimerodytes. In addition, based on morphological similarities between the monotypic genus Paratapinophis Angel, 1929 and Trimerodytes, we doubt about the validity of Paratapinophis. Following taxonomic changes in this work, the taxonomic account of the genus Trimerodytes, updated descriptions of its type species, and diagnostic key to Trimerodytes species are provided.
基金supported by the President of the Vietnam Academy of Science and Technology(VAST.CTG.03/16-17)the Ministry of Science and Technology(DLDLXH.19/15)to T.T.Nguyen+1 种基金partially funded by the National Geographic Society(Grant No.9492–14)the Rufford Foundation(Grant No.14877–1)to T.Q.Nguyen
文摘We describe a new species of Rhacophorus based on two adult specimens collected from Hoa Binh Province, northern Vietnam. Rhacophorus hoabinhensis sp. nov. is distinguishable from its congeners on the basis of a combination of the following morphological characters: size small(SVL 31.1–32.5 mm in males); head slightly longer than wide; vomerine teeth absent; snout short(SNL/SVL 0.16); dorsal skin smooth; forearm and tarsus with dermal fringes; dermal appendage at vent present; webbing formula on fingers Ⅰ12/3-12/3 Ⅱ1-2 Ⅲ1-1 Ⅳ and on toes Ⅰ3/4-1 Ⅱ1/2-1Ⅲ1/2-1 Ⅳ1-1/2Ⅳ; dorsal surface grey yellow with brown spots; lower jaw region dark grey, throat, chest and belly cream; anterior and posterior thighs, as well as ventral surface of tibia orange. The interspecific uncorrected genetic distances(16 S rRNA gene) between the new species from Hoa Binh and other analyzed congeners varied from 9.8% to 17.4%. In the phylogenetic analyses, the new species revealed to be a representative of Rhacophorus and was nested within the R. hoanglienensis-orlovi species group.
基金supported by the NAFOSTED research grant 106-NN.02-2016.19 to Phuong T.M.Nguyen.
文摘Objective:To investigate the antibiofilm activity of alphamangostin(AMG)loaded nanoparticle(nano AMG)against dental caries pathogen Streptococcus mutans.Methods:AMG was isolated from the peels of Garcinia mangostana L.using silica gel columns and chemically analysed by high performance liquid chromatography and nuclear magnetic resonance.Nano AMG was prepared using the solvent evaporation method combined with high-speed homogenization.The nanoparticles were characterized using dynamic light scattering,field emission scanning electron microscopy(FE-SEM)and Fourier transform infrared spectroscopy(FTIR).The toxicity of nano AMG in fibroblast NIH/3 T3 cell line was determined using MTT method.The antibiofilm effect of nano AMG was determined through the evaluation of biofilm formation by Streptococcus mutans using a 96-well plate.Biofilm biomass was quantified using crystal violet.Cell viability was observed under confocal microscopy using LIVE/DEAD Bac Light staining.Moreover,gene expression was determined by quantitative real-time PCR and membrane permeabilization activity by measuring the uptake of o-nitrophenol-β-D-galactoside.Results:Nano AMG size was in a range of 10-50 nm with a polydispersity index of<0.3 and zeta potential value of-35.2 m V.The size and the incorporation of AMG in the nanoparticles were confirmed by FE-SEM and FTIR analyses.The IC50 values of the test agents on NIH/3 T3 cells were(9.80±0.63)μg/m L for AMG and(8.70±0.81)μg/m L for nano AMG,while no toxicity was generated from excipients used to prepare nanoparticles.In the early stage of biofilm formation,treatment with 6.25μmol/L nano AMG caused a reduction in biofilm biomass up to 49.1%,compared to 33.4%for AMG.In contrast,biofilms at the late stage were more resistant to the test agents.At 96μmol/L(=10×MIC),nano AMG reduced only 20.7%of biofilm biomass while AMG did not showany effect.Expressions of gtf B and gtf C genes involved in biofilm formation were down-regulated 3.3 and 12.5 folds,respectively,compared to AMG(2.4 and 7.6 folds,respectively).LIVE/DEAD Bac Light fluorescence staining and microscopy observation indicated that biofilm cells were killed by both nano AMG and AMG at 48μmol/L(=5×MIC).In addition,membrane permeabilization activity was increased in a time dependent manner and higher in nano AMG treated cells compared to AMG.Conclusions:AMG coated nanoparticle can enhance AMG bioactivity and can be used as a new and promising antibiofilm agent.
基金partially supported by the Russian Foundation of Basic Research(RFBR 15-29-02771) to N.A.P.Molecular and phylogenetic analyses were completed with partial financial support from the Russian Science Foundation(RSF14-50-00029) to N.A.P
文摘We describe a new species of megophryid frog from Phu Yen Province in southern Vietnam. Leptolalax macrops sp. nov. is distinguished from its congeners by a combination of the following morphological attributes:(1) body size medium(SVL 28.0–29.3 mm in three adult males, 30.3 mm in single adult female);(2) supra-axillary glands present, creamy white; ventrolateral glands indistinct;(3) tympanum externally distinct;(4) dorsal skin roughly granular with larger tubercles, dermal ridges on dorsum absent;(5) rudimentary webbing present between fingers Ⅰ–Ⅱ and Ⅱ–Ⅲ; rudimentary webbing between all toes; fingers and toes without dermal fringes;(6) in life ventral surface greyish-violet with white speckling;(7) supratympanic fold distinct, dark brown in life;(8) iris bicolored, typically golden in upper half, fading to golden green in lower half;(9) tibia short(TbL/SVL 0.44–0.45 in males); and(10) eyes large and protuberant(ED/SVL 0.15–0.16 in males).From all congeners for which comparable sequences are available, the new species differs markedly in the 16 S rRNA mitochondrial gene sequence(P-distance>5.7%). The new species is currently known only from montane evergreen tropical forests of Song Hinh District, Phu Yen Province, and M'Drak District of Dak Lak Province at elevations of 470–630 m a.s.l.. We suggest the new species should be considered as Data Deficient following the IUCN's Red List categories. We also report a previously unknown Leptolalax mt DNA lineage from an evergreen tropical forest in the Hoa Thinh District of Phu Yen Province,which may also represent an undescribed species.
基金supported by the Programme National "Physique et Chimie du MilieuInterstellaire" (PCMI) of CNRS/INSU with INC/INP co-funded by CEA and CNESfinancial support from VNSC/VAST+4 种基金the NAFOSTED funding agency under grant number 103.99–2015.39the World Laboratorythe Odon Vallet Foundationthe Rencontres du Viet Namfunded by Graduate University of Science and Technology undergrant number GUST.STS.DT 2017-VL01
文摘Atacama Large Millimetre/sub-millimetre Array(ALMA) observations of CO(1–0) and CO(2–1) emissions from the circumstellar envelope of the asymptotic giant branch(AGB) star EP Aqr have been made with four times better spatial resolution than previously available. They are analysed with emphasis on the de-projection in space of the effective emissivity and flux of matter using as input a prescribed configuration of the velocity field, assumed to be radial. The data are found to display an intrinsic axisymmetry with respect to an axis making a small angle with respect to the line of sight. A broad range of wind configurations, from prolate(bipolar) to oblate(equatorial) has been studied and found to be accompanied by significant equatorial emission. Qualitatively, the effective emissivity is enhanced near the equator to produce the central narrow component observed in the Doppler velocity spectra and its dependence on star latitude generally follows that of the wind velocity with the exception of an omni-present depression near the poles. In particular, large equatorial expansion velocities produce a flared disc or a ring of effective emissivity and mass loss. The effect on the determination of the orientation of the star axis of radial velocity gradients, and possibly competing rotation and expansion in the equatorial disc, is discussed. In general,the flux of matter is found to reach a broad maximum at distances of the order of 500 AU from the star.Arguments are given that may be used to favour one wind velocity distribution over another. As a result of the improved quality of the data, a deeper understanding of the constraints imposed on morphology and kinematics has been obtained.
基金funded by the Vietnam National Foundation for Science and Technology Development (NAFOSTED) (No.103.99–2016.50)support from the World Laboratory,Rencontres du Viet Nam+2 种基金the Odon Vallet fellowships,Vietnam National Space CenterGraduate University of Science and Technologythe French CNRS programs PNP,PNPS and PCMI
文摘Observations by the Atacama Large Millimetre/sub-millimetre Array of the dust continuum and13 CO(3–2) millimetre emissions of the triple stellar system GG Tau A are analysed,giving evidence for a rotating gas disc and a concentric and coplanar dust ring. The present work complements an earlier analysis(Tang et al.) by exploring detailed properties of the gas disc. A 95% confidence level upper limit of 0.24′′(34 au) is placed on the disc scale height at a distance of 1′′(140 au) from the central stars. Evidence for Keplerian rotation of the gas disc is presented,with the rotation velocity reaching^3.1 km s^(-1) at 1′′ from the central stars,and a 99% confidence level upper limit of 9% is placed on relative contribution from a possible in-fall velocity. Variations of the intensity across the disc area are studied in detail and confirm the presence of a hot spot in the south-eastern quadrant. However several other significant intensity variations,in particular a depression in the northern direction,are also revealed. Variations of the intensity are found to be positively correlated to variations of the line width. Possible contributions to the measured line width are reviewed,suggesting an increase of the disc temperature and opacity with decreasing distance from the stars.
基金Supported by the Vietnam Ministry of Science and Technology(No.KC.09.23/16-20)the Scientific Research Activities for Senior Researchers in 2021(No.NCVCC23.05/21-21)+1 种基金the Chinese National Projects,the Science and Technology Basic Resources Investigation Program of China(No.2018FY100205)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA23050304)。
文摘A new species Lobophora tsengii is described from Bach Long Vy(Bailongwei)Island,Haiphong Province,Vietnam.The plants inhabit the subtidal zone and have predominantly erect fan-shaped thalli that attach to the substrate by a basal holdfast.The thallus is commonly composed of a single layer of large medullary cells with four layers of cortical cells on either side of the medulla.The newly collected specimens from the island are morphologically similar to those from Hainan Island,China,but differ from the New Caledonian ones in having thicker thallus.In molecular phylogenetic analyses based on concatenated rbcL and cox3 s equences,the specimens from the island were 100%identical to those from Hainan Island,China,and they formed a clade separating from other Lobophora species.Additionally,based on analyses of numerous cox3 s equences,our specimens were also distinguished from the closely related taxa occurring in New Caledonia,Kenya,and West Australia.Combining the morphological and molecular analyses,we conclude that our specimens represent a new species of Lobophora,which is apparently endemic to the Beibu Gulf(Gulf of Tonkin)and adjacent waters.
基金Chinese Academy of Sciences‘100 Talent’Program(B),Pre-research of Key Laboratory Fund for Equipment(No.61422070306)Shanghai Engineering Research Center of Space Engine(No.17DZ2280800)+1 种基金National Postdoctoral Program for Innovative Talents(No.BX201700248)China Postdoctoral Science Foundation(No.2017M622035)。
文摘To study the heating mechanism of electron cyclotron resonance thruster(ECRT)immersed in a non-uniform magnetic field,experiments and simulations are performed based on an electron cyclotron resonance plasma source at ASIPP.It is found that the first harmonic of electron cyclotron resonance is essential for plasma ignition at high magnetic field(0.0875 T),while the plasma can sustain without the first and second harmonics of electron cyclotron resonance at low magnetic field(till 0.0170 T).Evidence of radial hollow density profile indicates that upper hybrid resonance,which has strong edge heating effect,is the heating mechanism of low-field ECRT.The heating mode transition from electron cyclotron resonance to upper hybrid resonance is also revealed.Interestingly,the evolutions of electron temperature and electron density with input power experience a‘delayed’jump,which may be correlated with the different power levels required for cyclotron and ionization.Moreover,when the field strength decreased,the variation of electron density behaves in an opposite trend with that of electron temperature,implying a possible competition of power deposition between them.The present work is of great interest for understanding the plasma discharge in ECRT especially immersed in a non-uniform magnetic field,and designing efficient ECRT using low magnetic field for economic space applications.
文摘SW(Seaweed)is a valuable coastal resource for its use in food,cosmetics,medicine and other items.In this study,PS(PlanetScope)imagery was combined with field sampling to demonstrate the capability of mapping of SAV(Submerge Aquatic Vegetation)(including both SW and SG(Seagrass)beds)and biomass mapping of Sargassum meadows in An Chan coastal waters,Tuy An district,Phu Yen province,Vietnam.In term of SAV and Sargassum mapping,authors proposed an improved remote sensing technique based on Sagawa’s BRI(Bottom Reflectance Index)algorithm with attention to Tassan’s concept in discrimination of light attenuation coefficient Kd between shallow and deep waters.Authors’results showed high accuracy in mapping of SAV and Sargassum distribution with overall accuracy and Kappa coefficient of 92.52%and 0.8957,respectively.The classified class of SW(i.e.Sargassum sp.)then was separated absolutely from other classes in SAV map for estimation of Sargassum biomass.The red and green spectral pre-processed BRI channels(i.e.BRI3 and BRI2)of PS were used to estimate the Sargassum biomass using a multiple 2nd order polynomial regression model with very high accuracy(R2=0.9707;RMSE=±109.21 g/m2).The average total Sargassum biomass was 897.8 g/m2 with total Sargassum yield in whole region reaching a value of 449.57 tons in cover area of 50.32 ha of Sargassum meadows.This result opens the great potential of biomass and yield estimation of Sargassum and other SW meadows in coastal waters(including enough optically deep waters)by remote sensing techniques based on PS imagery.
