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Glacier-fed lakes on the Tibetan Plateau (TP) have undergone rapid expansions since the late 1990s, concurrent with the changing climate. However, the dominant cause(s) of lake area increases is still debated. To identify the drivers of lake expansion, we studied Aweng Co, a glacier-fed lake in the western TP, where surface area has increased (0.74 km2 year−1) since the late 1970s and most rapidly (0.998 km2 year−1) since the late 1990s. A water balance model was used to clarify the reasons for increased lake water volume, supported by stable isotope hydrology and the δ18O change recorded in recent sediments. Results showed that glacial meltwater probably had the biggest impact on changes in Aweng Co lake level in recent decades, but that precipitation was also an important contributor. Our study shows that δ18O of carbonate (δ18Ocarb) has great potential for indicating source changes of water supply in such lakes, but there is a need to be cautious when interpreting δ18Ocarb due to the influence of multiple hydrological factors, which can change in dominance over time.

TiO2–MoS2 composites composed of predominantly metallic MoS2 (MoS2 (1 T)) sheets and uniform dispersed P25 nanoparticles were prepared by one-pot hydrothermal synthesis assisted with cetyltrimethyl ammonium bromide (CTAB). It was proved that the incorporation of CTAB played an important role through endowing the as-prepared composites with a high MoS2 (1 T) purity of 69% and supporting a good interfacial contact between TiO2 and MoS2. Benefiting from the advanced structure, not only light harvesting but also electron transfer of the composites for photocatalytic reaction was improved, resulting in outstanding catalytic performance and long durability for the photodegradation of dye rhodamine B. The possible growth and photocatalytic mechanism are discussed in detail. This work provides a highly efficient photocatalyst with multiple merits, such as light harvesting with broadened window, electron delivery channels with high mobility, active sites with a massive number, effective migration of photoelectron and so on. Simultaneously, it promises a potential bottom-up synthesis strategy assisted with surfactant on fabrication of MoS2 (1 T)-based composites, which will contribute to the improvement in energy and environment fields.

Hainan of Southeast Asia has been regarded as a key area for understanding the Late Paleozoic tectonic regime and amalgamation process of the Indochina with South China Blocks that are not well constrained. This paper presents a set of new geochronological, elemental, and Sr–Nd isotopic data for the Paleozoic Bangxi and Chenxing metabasites in Central Hainan. The geochronological data show that the representative samples yield the 40Ar/39Ar plateau age of 328.1 ± 2.6 Ma and zircon U–Pb age of 330.7 ± 4.4 Ma, respectively. They are SiO2- and TiO2-poor, Al2O3-rich mafic rocks. The Chenxing samples are characterized by left-sloping chondrite-normalized REE and N-MORB-like multi-elemental patterns. The Bangxi samples have the E-MORB-like geochemical affinity. All samples show high e Nd(t) values ranging from +5.61 to +9.85. Such signatures suggest their origination of a MORB-like source with the input of subduction-derived components. Our investigation has verified the presence of the Carboniferous metabasites with both MORB- and arc- like geochemical affinities at the Bangxi-Chenxing area in Central Hainan. In combination with the available data from the Jinshajiang, Ailaoshan, and Song Ma suture zones, it is proposed for the development of a Carboniferous back-arc basin along the Ailaoshan–Song Ma and Central Hainan suture zones in response to the subduction of the Paleotethyan main Ocean.

Background Genic male sterility (GMS) line is an important approach to utilize heterosis in Brassica rapa, one of the most widely cultivated vegetable crops in Northeast Asia. However, the molecular genetic mechanisms of GMS remain to be largely unknown. Results Detailed phenotypic observation of ‘Bcajh97-01A/B’, a B. rapa genic male sterile AB line in this study revealed that the aberrant meiotic cytokinesis and premature tapetal programmed cell death occurring in the sterile line ultimately resulted in microspore degeneration and pollen wall defect. Further gene expression profile of the sterile and fertile floral buds of ‘Bcajh97-01A/B’ at five typical developmental stages during pollen development supported the result of phenotypic observation and identified stage-specific genes associated with the main events associated with pollen wall development, including tapetum development or functioning, callose metabolism, pollen exine formation and cell wall modification. Additionally, by using ChIP-sequencing, the genomic and gene-level distribution of trimethylated histone H3 lysine 4 (H3K4) and H3K27 were mapped on the fertile floral buds, and a great deal of pollen development-associated genes that were covalently modified by H3K4me3 and H3K27me3 were identified. Conclusions Our study provids a deeper understanding into the gene expression and regulation network during pollen development and pollen wall formation in B. rapa, and enabled the identification of a set of candidate genes for further functional annotation. Electronic supplementary material The online version of this article (10.1186/s12864-019-5637-x) contains supplementary material, which is available to authorized users.

Volcanic rocks are widely exposed within the Chiang Khong–Lampang–Tak igneous zone in NW Thailand. A representative rhyolite sample from the Chiang Khong area yielded a zircon U–Pb age of 230.7 ± 1.1 Ma (n = 20, MSWD = 0.98). The Chiang Khong rhyolites are characterized by low TiO2 (0.29–0.62 wt%) and MgO (0.04–0.82 wt%) with A/CNK values of 0.95–1.06 (one outlier at 1.47), and can be classified as highly fractionated I-type rhyolites. They are enriched in LILEs and LREEs, and depleted in HFSEs. Two representative samples have 87Sr/86Sr (i) ratios of 0.70497 and 0.70527, and the eNd (t) values fall at +1.1 and +1.3, respectively. eHf (t) and δ18O in zircon are between +4.7 to +12.0 and 5.3 to 5.9 ‰, respectively. Our geochemical data suggest that the Chiang Khong rhyolites formed by partial melting of juvenile mafic lower crust in a post-collisional setting. Deep crustal anatexis was probably induced by upwelling asthenospheric mantle, shortly after slab detachment subsequent to closure of the Paleo-Tethys.

The Changning-Menglian suture in SW Yunnan has been accepted as the Paleotethyan main ocean. However, it has been a matter of debate as to its southerly extension in NW Thailand (the Chiang Mai-Chiang Rai vs. Nan-Uttaradit zone). Our field investigation identified the high-iron basaltic rocks in the Chiang Dao Permian standard profile in NW Thailand. The high-iron rocks provide crucial records for understanding the controversy on the location of Paleotethyan main ocean in NW Thailand. The Early Permian high-iron samples show extremely high FeOt (20.96 wt.%–25.56 wt.%) and TiO2 (6.07 wt.%–6.34 wt.%) and low SiO2 (38.54 wt.%–43.46 wt.%) and MgO (1.61 wt.%–2.40 wt.%) contents. Such characteristics are similar to those of the Fenner differentiation trend rarely observed in the natural system, distinct from those of the “normal” Bowen trend. Their chondritenormalized REE and primitive mantle-normalized patterns are generally similar to those of typical OIB. The initial 87Sr/86Sr ratios and eNd(t) values range from 0.704 677 to 0.705 103 and 3.16 to 3.48, respectively, falling near the field of typical OIB (oceanic-island basalt). These data synthetically suggest that the Chiang Dao high-iron rocks are the products of high-degree partial melting of peridotite with Fe-rich eclogitic blobs/streaks in response to a seamount setting. In comparison with the Permian tectonic setting in SW Yunnan and NW Thailand, it is inferred that the Paleotethyan Ocean was located between the Shan-Thai terrane of Sibumasu and Sukhothai arc along the Inthanon zone of the Chiang Mai-Chiang Rai rather than Nan-Uttaradit zones.

The Wuliangshan Group occurs to the east of the Lancang giant igneous zone in SW Yunnan, and is mainly composed of low-grade metamorphosed sedimentary rocks. The group has been considered as the syn-orogenic product of the Baoshan with Simao-Indochina blocks. However, its depositional time and provenance remain to be poorly constrained. This paper presents zircon U-Pb dating and Lu-Hf-isotopic data for five representative sandstone samples from the Wuliangshan Group. The detrital grains yield a major age-peak at ∼259 Ma, and four subordinary age-peaks at ∼1 859, ∼941, ∼788, and ∼447 Ma, respectively. Our results suggest that the Wuliangshan metasedimentary sequence was deposited after Middle Triassic rather than previously-thought Cambrian. The detrital zircon age spectrum, along with in-situ Lu-Hf isotopic data suggest that the Wuliangshan Group might be a syncollisional sedimentary product related to the collision of Baoshan with Simao-Indochina blocks. It is inferred that the provenance of the Wuliangshan Group is mainly from the Simao/Yangtze blocks to the east rather than the Baoshan Block or Lancang igneous zone to the west.

High-quality VO2 films with precisely controlled thicknesses were grown on sapphire substrates by plasma-assisted oxide molecular beam epitaxy (MBE). To evaluate the degradation of semiconductor–metal transition (SMT) behavior of VO2 films under solar radiation, the temperature-driven SMT was investigated by measuring the electrical resistance during heating and cooling processes under solar simulator AM1.5, which provided illumination approximately matching the natural sunlight. The distinct reversible SMTs were observed for all the samples, whereas a remarkably conflicting trend in resistance change for extremely thin and thick samples was observed after exposure to the sunlight soaking system. The corresponding mechanism was proposed based on sunlight-induced resistance changes due to the transformation in the electron correlation and structural symmetry. The results might be especially attractive for some specific applications of VO2 films where solar radiation was inevitable.

VO2 films with precisely controlled thickness on the nanoscale ranging from 15 to 60 nm were grown on single crystal sapphire substrates by molecular beam epitaxy. X-ray diffraction and atomic force microscopy measurements indicated that high quality single phase VO2 films with condense and smooth surface and free of cracks could be achieved only when the film was thicker than 30 nm. The temperature-dependent resistance measurement indicated a drastic modification of metal–insulator transition (MIT) properties which was achieved through the variation of film thickness, especially the transition magnitude and curve abruptness. The corresponding mechanism was supposed to be associated with the tensile stress relaxation effect with increasing thickness caused by thermal mismatch within VO2 films, as demonstrated by Raman spectra. Our present finding provides an effective and convenient alternative to modulate the MIT properties of VO2 films.

SW Yunnan of China constituted part of the northern margin of Gondwana facing the proto-Tethys ocean in the early Paleozoic. However, the evolution of the region and its relationship with the accretionary orogenism have been poorly established. This paper reports a set of new zircon U–Pb age data and whole-rock major oxides, elemental and Sr–Nd isotopic data for early Paleozoic metavolcanic rocks from the previously defined Lancang Group and reveals the development of an Ordovician suprasubduction zone in SW Yunnan. Zircon U–Pb ages of 462 ± 6 and 454 ± 27 Ma for two representative samples indicate eruption of the volcanic rocks in the Late Ordovician. Geochemical data for the metavolcanic rocks together with other available data indicate a calc-alkaline affinity with high Al2O3 (13.04–18.77 wt%) and low TiO2 (0.64–1.00 wt%). They have Mg-numbers ranging from 62 to 50 with SiO2 of 53.57–69.10 wt%, compositionally corresponding to the high-Mg andesitic rocks. They display enrichments in LREEs and LILEs with significant Eu negative anomalies (δEu = 0.20–0.33), and depletions in HFSEs, similar to arc volcanic rocks. Their initial 87Sr/86Sr ratios range from 0.721356 to 0.722521 and eNd(t) values from −7.63 to −7.62 with Nd model ages of 2.06–2.10 Ga. Integration of ages and geochemical data with available geological observations, we propose the presence of Ordovician magmatism related to proto-Tethyan evolution in SW Yunnan and the metaigneous rocks formed in an island-arc setting. They were part of a regional accretionary orogen that extended along the northern margin of Gondwana during Neoproterozoic to early Paleozoic period.

Vanadium oxide (VO x ) thin films were grown on single crystal sapphire substrates by pulsed laser deposition under various O2 partial pressures. In situ AlN layer was inserted between the substrate and VO x films as induced stress layer. The significant influences of AlN layer on the structural, electric, and optical properties of the as-grown films were investigated systemically. The results indicated that pure monoclinic phase VO2 film with (020) preferred orientation was successfully achieved under the optimized O2 partial pressure. Moreover, a lowered semiconductor-to-metal transition temperature and a higher optical transmittance in visible and near-infrared regions were achieved due to the introduction of AlN-induced stress layer. Our achievements suggested that it might be a promising method to modulate VO2 transition characteristics by inducing AlN-induced stress layer.

ZnO thin films were deposited on graphite substrates by ultrasonic spray pyrolysis method with Zn(CH3COO)2·2H2O aqueous solution as precursor. The crystalline structure, morphology, and optical properties of the as-grown ZnO films were investigated systematically as a function of deposition temperature and growth time. Near-band edge ultraviolet (UV) emission was observed in room temperature photoluminescence spectra for the optimized samples, yet the usually observed defect related deep level emissions were nearly undetectable, indicating that high optical quality ZnO thin films could be achieved via this ultrasonic spray pyrolysis method. Considering the features of transferable and low thermal resistance of the graphite substrates, the achievement will be of special interest for the development of high-power semiconductor devices with sufficient power durability.

An Er2O3 coating-type selective emitter for themophotovoltaic application was prepared by plasma spray technology. The test results show that plasma spray technology could be used to prepare the Er2O3 coating-type selective emitter with good stability at 1400°C. Based on the measurements of the high temperature normal spectral emissivity and the spectral hemispherical emissivity of the samples at room temperature, the influence of the coating thickness was discussed, and the selective emission performance of the sample was evaluated using radiative efficiency as the criterion. The results demonstrate that the emission of substrate could not be neglected unless the coating thickness would be larger than the penetration depth, which is around 100 μm. The selective emission peak of the Er2O3 coating occurs at 1550 nm, matching well with the GaSb cells. However, the radiative efficiency is not larger than that of the SiC emitter, because the non-convertible emission of 1.725–5 μm accounts for a large proportion of the total radiation power, especially at high temperature. Effective suppression of this band emission is essential to the improvement of the radiation efficiency of the emitter.

ZnO nanorods (NRs) were grown perpendicularly on graphite substrates using low-temperature wet chemical bath deposition (CBD) with sputtered ZnO film as seed layer. The individual ZnO NRs exhibit single-crystalline feature with well defined hexagonal prism shape and smooth side facets. The high optical qualities of ZnO NRs on graphite substrates were demonstrated by the dominant near-band edge emission and nearly undetectable deep level emissions in room-temperature photoluminescence spectra. The extremely low average reflectance of 0.45 % was obtained for the ZnO NRs/graphite structure in the spectra range from 200 to 1100 nm, indicating that the reported ZnO NRs/graphite structures have significant opportunity for potential application in high-performance photovoltaic devices. Considering the excellent material characteristics of ZnO NRs and the versatile and fascinating features of graphite substrates, the achievements make it possible for the development of high-performance ZnO-based nano-devices even in transferable, flexible, or stretchable forms.