Folate metabolism is involved in the development and progression of various cancers. We investigated the association of single nucleotide polymorphisms (SNP) in folate-metabolising genes and their interactions with serum folate concentrations with overall survival (OS) and liver cancer-specific survival (LCSS) of newly diagnosed hepatocellular carcinoma (HCC) patients. We detected the genotypes of six SNP in three genes related to folate metabolism: methylenetetrahydrofolate reductase (MTHFR), 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR) and 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR). Cox proportional hazard models were used to calculate multivariable-adjusted hazard ratios (HR) and 95 % CI. This analysis included 970 HCC patients with genotypes of six SNP, and 864 of them had serum folate measurements. During a median follow-up of 722 d, 393 deaths occurred, with 360 attributed to HCC. In the fully-adjusted models, the MTRR rs1801394 polymorphism was significantly associated with OS in additive (per G allele: HR = 0·84, 95 % CI: 0·71, 0·99), co-dominant (AG v. AA: HR = 0·77; 95 % CI: 0·62, 0·96) and dominant (AG + GG v. AA: HR = 0·78; 95 % CI: 0·63, 0·96) models. Carrying increasing numbers of protective alleles was linked to better LCSS (HR10–12 v. 2–6 = 0·70; 95 % CI: 0·49, 1·00) and OS (HR10–12 v. 2–6 = 0·67; 95 % CI: 0·47, 0·95). Furthermore, we observed significant interactions on both multiplicative and additive scales between serum folate levels and MTRR rs1801394 polymorphism. Carrying the variant G allele of the MTRR rs1801394 is associated with better HCC prognosis and may enhance the favourable association between higher serum folate levels and improved survival among HCC patients.

Fe is a common substituent in palygorskites (Plg), but its effect on the microscopic properties is unclear. In the current study, molecular dynamics (MD) simulations were carried out to investigate the effect of Fe on the properties of the nano-pores in Plg. The structures and dynamics of water and Na+ ions in the pores were computed by analyzing the MD trajectories. The results revealed that for both Fe-containing and ordinary Plg, zeolitic water molecules can diffuse into the pores with very low mobility whereas Mg-coordinated water fails to escape. Na+ ions show no obvious diffusivity because they are fixed above the Si–Osix-membered rings. Detailed comparison indicates that Fe-substitution has no significant influence on the pore properties of Plg.

Surface elevation data for sea ice in the northwesternty - Weddell Sea, Antarctica, collected by a helicopter-borne laser altimeter during the Winter Weddell Outflow Study 2006, were used to estimate the form drag on pressure ridges and its contribution to the total wind drag, and the air-ice drag coefficient at a reference height of 10 m under neutral stability conditions (C dn(10)). This was achieved by partitioning the total wind drag into two components: form drag on pressure ridges and skin drag over rough sea-ice surfaces. The results reveal that for the compacted ice field, the contribution of form drag on pressure ridges to the total wind drag increases with increasing ridging intensity Ri (where Ri is the ratio of mean ridge height to spacing), while the contribution decreases with increasing roughness length. There is also an increasing trend in the air-ice drag coefficient C dn(10) as ridging intensity R i increases. However, as roughness length increases, C dn(10) increases at lower ridging intensities (Ri < 0.023) but decreases at lower ridging intensities (0.023 < Ri < 0.05). These opposing trends are mainly caused by the dominance of the form drag on pressure ridges and skin drag over rough ice surfaces. Generally, the form drag becomes dominant only when the ridging intensity is sufficiently large, while the skin drag is the dominant component at relatively larger ridging intensities. These results imply that a large value of C dn(10) is caused not only by the form drag on pressure ridges, but also by the skin drag over rough ice surfaces. Additionally, the estimated drag coefficients are consistent with reported measurements in the northwestern Weddell Sea, further demonstrating the feasibility of the drag partition model.

During the 19th Chinese National Antarctic Research Expedition from December 2002 to January 2003, 1085 icebergs were observed along the cruise track within the range 58–68° S in the Southern Ocean using the marine radar on the R/V Xuelong. These icebergs were located mainly in the Ross Sea, Weddell Sea and Prydz Bay with lengths ranging from 68 to 8169 m. Both power-law and Weibull functions are applied to the curve fitting of cumulative probability distribution of iceberg length in each region. The results reveal that the power-law function underestimates the measured data in the middle of the data, but overestimates them for both the smallest and largest iceberg sizes, whereas the Weibull function underestimates the measured data when iceberg length is large enough. To reduce the relative error increasing with iceberg length, the Weibull function is used only in fitting to iceberg lengths less than a threshold value of iceberg size (L t) and the power-law function is used in fitting to iceberg lengths >L t. The improved curve fits show a good correlation over the full range of the data. This clearly reveals that an upper limit of iceberg length exists in the good agreement between the Weibull function and the measured data, which is attributed to different thermodynamic effects on calving processes and subsequent modification of large and small icebergs. In addition, iceberg size in Prydz Bay increases and then decreases when approaching the Amery Ice Shelf as a result of bergy bits and growlers calved from large icebergs in front of the ice shelf.

Airborne and spaceborne remote sensing of ice freeboard offers a good method of retrieving ice thickness in the polar oceans. However, its accuracy is highly limited by the factors altering the hydrostatic equilibrium of ice floes, such as snow cover and melt ponds which change the surface loading on the ice volume. In contrast to the abundant studies on snow loads, little attention has been paid to the role of melt ponds, partly owing to the difficulties of freeboard measurements during the melt season. To help fill this gap and provide a basis for possible instruments and algorithms being able to access ice freeboard with melting surface in future, a theoretical model was developed to investigate the uncertainty in ice thickness retrieval due to surface melting. First, the ice thickness was related to the freeboard, snow depth, melt pond size and densities of snow, ice and water, and then a sensitivity analysis was carried out to study the influence of melt pond morphology. The results show that melting ice has a much lower mean thickness than ice without a melting surface, although with the same freeboard because of a loss of floe weight due to melting. During pond evolution, a floe gains weight when ponds deepen on the vertical scale, but loses weight when they widen on the horizontal scale, resulting in increasing mean ice thickness with decreasing pond depth and fraction. Freeboard is found to be the major source of uncertainty in the retrieved thickness of first-year ice (FYI), while it is ice density in the case of multi-year ice (MYI). The ratio of ice draft to freeboard ranges from 3.0 to 6.2 for FYI and 2.0 to 4.1 for MYI, agreeing with field observations during melting seasons.

The ice cover on the Qinghai–Tibetan Plateau plays an important role in the environmental and ecological systems. We analyze the in situ measurements of ice growth and examine the thermal diffusivity of thermokarst lake ice in the Beiluhe basin. We evaluate numerically the change of thermal diffusivity of thermokarst lake ice with changing ice temperature using an optimal control model. In a higher ice temperature regime (–3 to 0°C), the thermal diffusivity of thermokarst lake ice decreases exponentially with increasing ice temperature, and approaches the thermal diffusivity value of fresh water near the freezing-point temperature. In a lower ice temperature regime (–15 to –3°C), the thermal diffusivity increases slowly with decreasing ice temperature.

Croftonweed is an invasive plant in southwest China. We examined the relationships between its invasion patterns and native plant diversity at different spatio-temporal scales. At the 25 m2 scale, invasion success was negatively correlated with native plant diversity, indicating that resource availability might be the dominant factor regulating community invasibility. At the 400-m2 scale, both negative and positive relationships were detected, possibly identifying a spatial scale threshold where extrinsic environmental factors became more important to community invasibility. At the vegetation province scale, variations in physical environment outweighed the importance of intrinsic biotic factors and positive relationships between diversity and invader success were found. Native plant diversity also inhibited croftonweed over the course of community succession and at the early stages of invasion at local spatial scales. However, the changing relationship might be an artifact of sampling at different spatial scales.

Roads and streams are important conduits for the spread of invasive species, and croftonweed is an invasive plant in southwest China. We established six transects along one road and stream in Huili County, Sichuan Province to determine the pattern of invasion and identify major factors potentially influencing it. Results demonstrated that the invasion (cover, abundance, and number of clusters) of croftonweed declined significantly with distance from the road and stream. However, after compensation for environmental factors, only distance from the road was significantly negatively related to number of clusters of this plant. Instead, native plant species cover and richness were significantly negatively associated with croftonweed invasion along the road; elevation and native species cover were negatively correlated with the invasion along the stream. These findings indicated that roads and streams were main conduits for the spread of croftonweed in southwest China, and reduced native species cover could facilitate invasion by croftonweed in habitats along roads and streams.