Thermal–moisture dynamics and thermal stability of active layer in response to wet/dry conditions in the central region of the Qinghai–Tibet Plateau,China

The amount of rainfall varies unevenly in different regions of the Qinghai-Tibet Plateau, with some regions becoming wetter and others drier. Precipitation has an important impact on the process of surface energy balance and the energy-water transfer within soils. To clarify the thermal-moisture dynamics and thermal stability of the active layer in permafrost regions under wet/dry conditions, the verified water-vapour-heat coupling model was used. Changes in the surface energy balance, energy-water transfer within the soil, and thickness of the active layer were quantitatively analyzed. The results demonstrate that rainfall changes significantly affect the Bowen ratio, which in turn affects surface energy exchange. Under wet/dry conditions, there is a positive correlation between rainfall and liquid water flux under the hydraulic gradient;water vapour migration is the main form under the temperature gradient, which indicates that the influence of water vapour migration on thermalmoisture dynamics of the active layer cannot be neglected. Concurrently, regardless of wet or dry conditions,disturbance of the heat transport by conduction caused by rainfall is stronger than that of convection by liquid water. In addition, when rainfall decreases by 1.5 times(212 mm) and increases by 1.5 times(477 mm), the thickness of the active layer increases by 0.12 m and decreases by 0.21 m, respectively. The results show that dry conditions are not conducive to the preservation of frozen soil;however, wet conditions are conducive to the preservation of frozen soil, although there is a threshold value. When this threshold value is exceeded, rainfall is unfavourable for the development of frozen soil.

Application of ultrasound-guided balloon occlusion in cesarean section in 130 cases of sinister placenta previa

Objective:To investigate the clinical utility of ultrasound-guided balloon occlusion in cesarean section in patients with sinister placenta previa.Methods:The Interventional and Ultrasound Departments of the authors’center assisted obstetrics to complete cesarean section in cases of sinister placenta previa.A total of 130 patients with implanted sinister placenta previa were diagnosed using obstetrical ultrasound and magnetic resonance imaging(MRI).Before cesarean section,the balloon was positioned in the bilateral radial or abdominal aorta.Immediately after delivery of the fetus,the balloon was temporarily filled to transiently seal the target vessel.According to the obstetrician’s assessment of hemostasis,the balloon was withdrawn at the appropriate time.Among the 130 patients,there was one case of abdominal aortic occlusion,with 129 cases blocked by the bilateral common iliac artery.Results:All 130 cases were successfully blocked,with an average blocking time of<15 min,while intraoperative blood loss was 800–1500 ml.Conclusion:Ultrasound-guided balloon blocking treatment before cesarean section can mitigate the dangers of placenta previa and significantly reduce blood loss with no exposure to X-ray radiation.Thus,the technique merits serious consideration.

Molecular phylogeny of tribe Atraphaxideae(Polygonaceae)evidenced from five cpDNA genes

Traditionally, Atraphaxis, Calligonum, Pteropyrum and Parapteropyrum are included in the tribe Atraphxideae. Recently, sequence data has revealed that this tribe is not monophyletic. The structure of the tribe was examined by adding more taxa and sequences to clarify the congruence between morphology and molecular phylogeny, the systematic placements of four genera in Polygonaceae, as well as the infra-generic relationships of Atraphaxis and Calligonum within Atraphaxideae. Five chloroplast genes, atpB-rbcL, psbA-trnH, trnL-tmF, psbK-psbl, and rbcL of Atraphaxis, Calligonum, Pteropyrum, and Parapteropyrum were sequenced. The non-monophyly of Atraphaxideae was confirmed. Atraphaxis and Calligonum, respectively, formed a monophyletic group that was well supported. Calligonum is closely related to Pteropyrum; Atraphaxis is sister to Polygonum s. str. and Parapteropyrum is allied with Fagopyrum. Although the morphology suggested the four genera should form a tribe, the molecular data indicated Atraphaxideae was not one monophyletic group. The clades identified within Atraphaxis corresponded well with the current sectional classification based on morphological features. As for Cal- ligonum, Medusa was identified as a non-monophyletic section.

Monophyly and infrageneric variation of Corispermum L.(Chenopodiaceae),evidence from sequence data psbB-psbH,rbcL and ITS

Corispermum is one of the most problematic taxonomic genera in Chenopodiaceae.To understand the phylogeny and infrageneric variation of Corispermum,we sequenced the nuclear ribosomal ITS region and two chloroplast DNA regions(rbcL and psbB-psbH) of 22 species and three varieties of Corispermum and the related genus Agriophyllum.Several representative species of Salsola,Suaeda,Chenopodium,Kalidium and Camphorosma served as outgroups.Our phylogenetic trees confirm that the tribe Corispermeae is monophyletic,Corispermum and Agriophyllum have a close relationship.Corispermum is demonstrated to be monophyletic,and contains at least four clades which,consequently,are served as the foundation of the infrageneric sectional variation of Corispermum,in terms of a combination of molecular data and morphological characters.The evolution of morphological characters for fruit wing and apex,two important characters in generic classification,is consistent with the sectional division of Corispermum,especially to the East Asian and Chinese taxa.

Resurrection of the genus Botrydium Spach(Chenopodiaceae),with a description of four new species from China,Peru and Burundi

Based on specimens from twenty-one herbaria from China and USA,as well as observations using SEM,the genus Botrydium is resurrected as Neobotrydium.It has a number of distinctive characters:the plants are covered with granular hairs and granulated globular gland-grains,strong smell,and dichasia.Neobotrydium is removed from Chenopodium.The differences between Neobotrydium and Chenopodium,as well as circumscriptions of five glandular genera,Neobotrydium,Cycloloma,Roubieva,Ambrina,and Dysphania are discussed.Neobotrydium comprises twenty species which occur in Asia,Europe,North Africa,North America to Northwest of South America and Australia.Four new species are described:Neobotrydium corniculatum and Neobotrydium ornithopodum from China,Neobotrydium peruensis from South America,and Neobotrydium burundiensis from Africa.A diagnostic key is presented.

Investigation on Thermal Insulation and Mechanical Strength of Lightweight Aggregate Concrete and Porous Mortar in Cold Regions

Thermal insulation is an important indicator to evaluate the construction material in cold region engineering.As we know,adding the industrial waste as lightweight aggregate or creating the pore inside the cement-based composite could make the texture loose,and the thermal insulating capacity of the material would be improved with this texture.Using these methods,the industrial by-product and engineering waste could be cycled in an efficient way.Moreover,after service the fragmented cement composites paste could be used as aggregate in the thermal insulating concrete again.While the porous texture is not favorable for the mechanical strength and long-term durability in a cold environment.To balance the above three requirements from two opposite directions,different processing methods were applied to create the thermal insulation concrete/mortar.Firstly,the organic/inorganic lightweight aggregate,including the Expanded Polystyrene(EPS),Expanded Perlite(EP),and Ceramsite(CRMST)particles,were applied to create the Lightweight Aggregate Concrete(LWAC).As the comparative tests,the expanded Superabsorbent Polymer(SAP)hydrogel and Air-Entraining Agent(AEA)were also introduced to create the porous mortar.The above concrete/mortar was tested in the normal state and under the Freeze-Thaw cycle to explore the engineering performance in cold regions.During the experimenting process,the thermal insulation,mechanical strength,and frost resistance of these cement-based composites were investigated,and an optimal thermal insulation concrete/mortar was determined.

A cladistic scenario of Southern Pacific biogeographical history based on Nothofagus dispersal and vicariance analysis

Nothofagus is regarded as a key group for interpreting Southern Pacific biogeographical history.Based on a molecular phylogenetic tree,a quantitative dispersal-vicariance analysis(DIVA) of the genus is presented.The results indicate that the ancestral area of Nothofagus is a broad realm almost including the total extant distribution pattern of the genus rather than a so-named center of origin.Integrated with the paleogeography,the time of origin and subsequent diversification is inferred to have started in the Late Cretaceous.Most vicariance and dispersal events should be contained in that period.Vicariance events versus dispersal events play a dominant rule in speciation.The dispersal events are hypothesized to happen from the Late Cretaceous to Eocene in terms of the geological history.Rich fossils are collected in the Eocene.South America,comprising three subgenera of Nothofagus,should be considered as a diversification region,in which the distribution of the species of subgenus Fuscospora and subgenus Nothofagus are explained by dispersal events during the Late Cretaceous-Late Eocene.

Phylogenetic Origin of Phyllolobium with a Further Implication for Diversification of Astragalus in China

Astragalus is a species-rich genus occurring in the western arid habitats in China and its diversification and infrageneric relationships in this region remain unclear. In the present study, based on molecular data, we aim to （i） test whether Phyllolobium （previously treated as a subgenus Pogonophace in Astragalus） should be warranted; and （ii） date the origin of Phyllolobium and probable diversification of Astragalus sensu stricto （s.s.）. We sequenced five species from Phyllolobium first and collected all related sequences from the genus, Astragalus s.s and their close relatives （Oxytropis and Caragana etc.）. Our phylogenetic analyses suggested that all species of Phyllolobium comprise a monophyletic sister-group to genera of the subtribe Coluteinae. Molecular dating suggested that Phyllolobium and Astragalus s.s. originated around 8 and 10 million years ago. These two estimates are highly consistent with the intense uplifts of the Qinghai-Tibetan Plateau inferred from geological evidence. In addition, one section of Pogonophace （Sect. Robusti） was estimated to originate 2.5 million years ago and this section with a tendency for dry habitats seems to be evidence of Asian intensified aridity resulting from the intense uplift of the Qinghai-Tibetan Plateau.

Occurrence of polycyclic aromatic hydrocarbons in the estuarine sediments of the Taihu Lake and their associated toxic effects on aquatic organisms

Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous toxic organic pollutants in the natural environment that are strongly associated with socioeconomic activities.Exploring the distribution,sources,and ecological toxicity of PAHs is essential to abate their pollution and biological risks.The 16 priority PAHs in different lakeside city estuarine sediments in the northern Taihu Lake in China were determined using gas chromatography-mass spectrometry.Results showed that total concentrations of PAHs(ΣPAHs)ranged from 672.07 to 5858.34 ng g^(^(-1)),with a mean value of 2121.37 ng g^(^(-1)).High-molecular-weight PAHs(4-6 rings)were dominant,accounting for 85%of theΣPAHs detected.Due to the barrier of gate/dam in the estuarine area,the concentrations of PAHs in the sediments were significantly different between the river mouth and lake side.Changes in total organic carbon(TOC)content and the spatial distribution of PAHs in the sediments were consistent.Sediment pollution assessment explored using the fuzzy evaluation model indicated 75%of slight PAH pollution.Some estuarine sediments(22%)concentrated in the east of the Wuli Lake in the Meiliang bay of the Taihu Lake were moderately or heavily polluted.The PAHs may lead to occasional detrimental biological consequences in the area.Diagnostic ratios and principal component analysis-multiple linear regression suggested vehicle emission and natural gas combustion as the primary PAH contributors(81%).