Biofilm formation under high temperature causes the commensal bacteria Bacillus cereus WPySW2 to shift from friend to foe in Neoporphyra haitanensis in vitro model     

Liu  Qiqin  Yang  Rui  Sun  Xiaoxiao  Zhou  Xinqian  Chen  Haimin 《中国海洋湖沼学报》2023,41(1):229-240

Although biofilm formation may promote growth, biofilms are not always beneficial to their hosts. The biofilm formation characteristics of Bacillus cereus WPySW2 and its changes at different temperatures were studied. Results show that B. cereus WPySW2 promoted the growth of Neoporphyra haitanensis (an economically cultivated seaweed) at 20 °C but accelerated algal rot at 28 °C. Thicker B. cereus WPySW2 biofilms covered the surface of N. haitanensis thalli at 28 °C, which hindered material exchange between the algae and surrounding environment, inhibited algal photosynthesis and respiration, and accelerated algal decay. Compared with planktonic bacteria, mature biofilm cells had lower energy consumption and metabolic levels. The biofilm metabolic characteristics of B. cereus WPySW2 changed significantly with temperature. High temperature accelerated biofilm maturation, which made it thicker and more stable, allowing the bacteria to easily adapt to environmental changes and obtain greater benefits from their host. High temperature did not affect the production or increased the abundance of toxic metabolites, indicating that the negative effects of B. cereus WPySW2 on algae were not caused by toxins. This study shows that increased temperature can transform a harmless bacterium into a detrimental one, demonstrating that temperature may change the ecological function of phycospheric bacteria by affecting their morphology and metabolism.

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Geochemical and geochronological study of the Sanshui basin bimodal volcanic rock suite,China: Implications for basin dynamics in southeastern China     

Haimin Zhou  Long Xiao  Yuexia Dong  Chunzeng Wang  Fangzheng Wang  Pingze Ni 《Journal of Asian Earth Sciences》2009,34(2):178-189

Sanshui basin is one of the typical Mesozoic–Cenozoic intra-continental rift basins with voluminous Cenozoic volcanic rocks in southeastern China. Thirteen cycles of volcanic eruptions and two dominant types of volcanic rocks, basalt and trachyte–rhyolite, have been identified within the basin. Both basalt and trachyte–rhyolite members of this bimodal suit have high values of εNd (+2.3 to +6.2) and different Sr isotopic compositions (initial ⁸⁷Sr/⁸⁶Sr ratios are 0.70461–0.70625 and 0.70688–0.71266 for basalts and trachyte–rhyolite, respectively), reflecting distinct magma evolution processes or different magma sources. The results presented in this study indicate that both of the trachyte–rhyolite and basaltic magmas were derived from similar independent primitive mantle, but experienced different evolution processes. The trachyte-rhyolitic magma experienced significant clinopyroxene and plagioclase fractionational crystallization from deeper magma chamber with significant crustal contamination, while the basaltic magmas experienced significant olivine and clinopyroxene fractionational crystallization in shallower magma chamber with minor crustal contamination. New zircon U–Pb dating confirms an initial volcanic eruption at 60 Ma and the last activity at 43 Ma. Geologic, geochemical, and geochronological data suggest that the inception of the Sanshui basin was resulted from upwelling of a mantle plume. The Sanshui basin widened due to subsequent east–west extension and the subsequent volcanism constantly occurred in the center of the basin. Evidence also supports a temporal and spatial association with other rift basins in southeastern China. The upwelling mantle plume became more active during late Cenozoic time and most likely triggered opening of other basins, including the young South China Sea basin.  相似文献   

New SHRIMP U–Pb zircon ages of granitic rocks in the Hida Belt,Japan: Implications for tectonic correlation with Jiamushi massif     

Xilin Zhao  Jianren Mao  Haimin Ye  Kai Liu  Yutaka Takahashi 《Island Arc》2013,22(4):508-521

Granitoids in the Hida region of Japan encompass two main rock types: younger type‐1 granites and older type‐2 granites. Sensitive high mass‐resolution ion microprobe (SHRIMP) U–Pb zircon dating of older type‐2 granites collected from the Tateyama area show similar ages of 245 ± 2 Ma and 248 ± 5 Ma for two gneissose granites, while a significantly younger intrusion age of 197 ± 3 Ma was determined for the younger type‐1 granites collected from the Hayatsukigawa River which belongs to the Okumayama pluton. A felsic gneiss sample (07HI‐3) collected from the right bank of the Hayatsukigawa River yielded multiple complex ages at 330 ± 6 Ma, indicating the timing of the Hida regional tectono‐thermal events that formed the Hida gneisses; 243 ± 8 Ma, representing the timing of intrusion of the augen granite; and 220 Ma, indicating the timing of regional dextral ductile shearing that caused a repeated recrystallization of metamorphic rocks in the study area. Considering the geochronological data, the rock types and assemblages, basement, and Sr–Nd isotopic constraints, we propose that the Hida Belt separated from the Jiamushi massif, which is located in the eastern margin of the Central Asian Orogenic Belt.  相似文献   

First Light of the Near-Infrared Narrow-Band Tunable Birefringent Filter at Big Bear Solar Observatory     

Wenda Cao  Klaus Hartkorn  Jun Ma  Yan Xu  Tom Spirock  Haimin Wang  Philip R. Goode 《Solar physics》2006,238(1):207-217

We discuss a near-infrared (NIR) narrow-band tunable birefringent filter system newly developed by the Big Bear Solar Observatory (BBSO). This is one of the first narrow-bandpass NIR filter systems working at 1.56 μm which is used for the observation of the deepest solar photosphere. Four stages of calcite were used to obtain a bandpass of 2.5 Å along with a free spectral range (FSR) of 40 Å. Some unique techniques were implemented in the design, including liquid crystal variable retarders (LCVRs) to tune the bandpass in a range of ±100 Å, a wide field configuration to provide up to 2° incident angle, and oil-free structure to make it more compact and handy. After performing calibration and characteristic evaluation at the Evans Facility of the National Solar Observatory at Sacramento Peak (NSO/SP), a series of high-resolution filtergrams and imaging polarimetry observations were carried out with the Dunn Solar Telescope of NSO/SP and the 65-cm telescope of BBSO, in conjunction with the high-order adaptive optics system and the Fabry–Pérot Interferometer (FPI). In this paper, we describe the optical design and discuss the calibration method. Preliminary observations show that it is capable of serving as either a stand-alone narrow-band filter for NIR filtergram observations or an order-sorting filter of a FPI applied to NIR two-dimensional imaging spectro-polarimetry.  相似文献   

高台盐湖苦卤模拟天然蒸发研究          下载免费PDF全文

李海民  李姚兴  孙玉芬 《盐湖研究》1999,7(4):43-48

以高台盐湖冻硝析盐后苦卤,模拟当地气候的条件,进行兑卤蒸发和直接蒸发的试验。试验结果表明冻硝后苦卤可以制取钾混盐,作为生产硫酸钾的原料。  相似文献   

粤北澜河变质岩的地球化学特征及其地质意义   总被引：1，自引：0，他引：1  

吴烈勤沈渭洲  黄国龙凌洪飞 叶海敏 《地质论评》2006,52(5):609-617

粤北澜河变质岩主要由黑云母变粒岩和白云母绿泥片岩组成。根据主要元素、微量元素与稀土元素组成以及在各种相关判别图解上的投影,黑云母变粒岩的原岩为砂质岩,白云母绿泥片岩的原岩为泥质岩,它们主要是在被动大陆边缘的沉积环境中形成。根据黑云母变粒岩中单颗粒碎屑锆石最小U—Pb年龄为725Ma以及加里东期或早于加里东期变质的事实,原岩的沉积时间为早古生代。澜河变质岩的Sm—Nd同位素组成表明,它们的物源区为古元古代地壳,形成过程中没有年轻地壳物质加入。  相似文献   

海洋微藻β-葡聚糖的生物活性分析     

周成旭  田甜  陈海敏  严小军  骆其君 《海洋与湖沼》2014,45(1):66-72

为研究微藻来源的β-葡聚糖生物活性以及是否存在种间差异,从6种海洋硅藻和定鞭藻(Haptophyte)中制备了β-葡聚糖,进行了抗肿瘤、抗氧化、抑菌活性的分析和比较。6种微藻分别为:中肋骨条藻(Skeletonema costatum)、三角褐指藻(Phaeodactylum tricornutum)、假微型海链藻(Thalassiosira pseudonana)、柔弱角刺藻(Chaetoceros debilis)、球等鞭金藻(Isochrysis galbana)、颗石藻(Pleurochrysis sp.)。研究结果显示:1.微藻β-葡聚糖对Hela肿瘤细胞有细胞毒性:浓度为50—100μg/mL时,假微型海链藻β-葡聚糖的活性最高;200μg/mL时,颗石藻的最高,但活性均未超过50%。2.以DPPH和DCFH-DA两种方法检测抗氧化活性发现,6种微藻β-葡聚糖均有浓度相关的抗氧化活性,并且对氧自由基的清除率相对较高;当β-葡聚糖浓度为400μg/mL时,其清除率可达72%—74%。3.对不同菌的作用有差异:有浓度相关的抑制大肠杆菌的作用,浓度为400μg/mL时,抑菌率可达60%;有促进金黄色葡萄球菌生长的作用,其中,仅中肋骨条藻的β-葡聚糖有浓度相关的作用。结果表明,几种硅藻和定鞭藻的β-葡聚糖生物活性功能相同,都具有抗肿瘤、抗氧化以及抑菌或促菌作用,活性大小与浓度有明显的相关性。相同浓度或作用时间下,其活性大小及活性饱和性具有微藻种间差异。这为研究和利用微藻及其天然产物提供了参考。  相似文献   

The association of flares to cancelling magnetic features on the sun     

Silvia H. B. Livi  Sara Martin  Haimin Wang  Guoxiang Ai 《Solar physics》1989,121(1-2):197-214

Previous work relating flares to evolutionary changes of photospheric solar magnetic fields are reviewed and reinterpreted in the light of recent observations of cancelling magnetic fields. In line-of-sight magnetograms and H-alpha filtergrams from Big Bear Solar Observatory, we confirm the following 3 associations: (a) the occurrence of many flares in the vicinity of emerging magnetic flux regions (Rust, 1974), but only at locations where cancellation has been observed or inferred; (b) the occurrence of flares at sites where the magnetic flux is increasing on one side of a polarity inversion line and concurrently decreasing on the other (Martres et al., 1968; Ribes, 1969); and (c) the occurrence of flares at sites where cancellation is the only observed change in the magnetograms for at least several hours before a flare (Martin, Livi, and Wang, 1985). Because cancellation (or the localized decrease in the line-of-sight component of magnetic flux) is the only common factor in all of these circumstances, suggest that cancellation is the more general association that includes the other associations as special cases. We propose the hypothesis that cancellation is a necessary, evolutionary precondition for flares. We also confirm the observation of Martin, Livi, and Wang (1985) that the initial parts of flares occur in close proximity to cancellation sites but that during later phases, the flare emission can spread to other parts of the magnetic field that are weak, strong, or not cancelling.  相似文献   

Magnetic flux transport of decaying active regions and enhanced magnetic network     

Haimin Wang  Harold Zirin  Guoxiang Ai 《Solar physics》1991,131(1):53-68

Several series of coordinated observations on decaying active regions and enhanced magnetic network regions have been carried out jointly at Big Bear Solar Observatory (BBSO) and Huairou Solar Observing Station of the Bejing Astronomical Observatory in China. The evolution of magnetic fields in several regions was followed closely for 3 to 7 days. The transport of magnetic flux from the remnants of decayed active regions was studied. Three related topics are included in this paper. (1) We studied the evolution and lifetime of the magnetic network which defines the boundaries of supergranules. The results are consistent with our earlier studies: network cells have an average lifetime of about 70 hours; 68% of new cells appeared by growing from a single network magnetic element; 50% of decaying cells disappeared by contracting to a network element. (2) We studied the magnetic flux transport in an enhanced network region in detail, and found the diffusion rate to be negative, i.e., there was more flux moving towards the decayed active region than away from it. We found several other cases where the magnetic diffusion rate does not agree with Leighton's model. The slow diffusion rate is likely due to the fact that the average velocity of larger magnetic elements, which carry most of the magnetic flux, is less than 0.1 km s^–1; their average lifetime is longer than 100 hours. (3) We briefly described some properties of Moving Magnetic Features (MMFs) around a sunspot (detailed discussion on MMFs will be presented in a separate paper). In this particular case, the MMFs did not carry net flux away from the central spot. Instead, the polarities of MMFs were essentially mixed so that outflowing positive and negative fluxes were roughly balanced. During the 3-day period, there was almost no net flux accumulation to form a moat. The cancellation of MMFs of opposite polarities at the boundary of the super-penumbra caused quite a few surges and H brightenings.  相似文献   

Aoyitake plagiogranite in western Tarim Block, NW China: Age, geochemistry, petrogenesis and its tectonic implications   总被引：1，自引：2，他引：1  

ZHANG Chuanlin  YU Haifeng  YE Haimin  ZHAO Yu  ZHANG Dongsheng 《中国科学D辑(英文版)》2006,49(11):1121-1134

SHRIMPP U-Pb zircon age and geochemical and Nd isotopic data are reported for the Aoyitake plagiogranite in western Tarim Block, NW China. The plagiogranite intruded the Middle Pro- terozoic and Lower Carboniferous with an exposure area of ca. 60 km2 and crystallized at 330.7±4.8 Ma. Rock types mainly include tonalite, trondhjemite and minor amounts of diorite and quartz-diorite. Feldspars in the rocks are dominated by oligoclase-andesine, and minor perthite observed locally. The granites are sodic with Na/K ratios (molar) between 4 and 87. Total REE (50-220 ppm) show a clear positive correlation with SiO2. There is no LRRE/HREE fractionation (LaN/YbN=0.5-1.5), me- dium negative Eu anomalies (δ Eu=0.3-0.6), high Y content and low Sr/Y ratio (~1.0). These granites exhibit relatively juvenile Nd T2DM model ages of 470 to 580 Ma and positive εNd(331 Ma) values of 6.23 to 7.65. The aforementioned characteristics are similar to those of ocean island or ocean ridge plagiogranites. However, the regional geology, especially its scale, precludes that the plagiogranite pluton was derived directly from fractionational crystallization of mantle-derived basaltic magma. We interpreted that the primary magma of the pluton might be tonalitic in composition generated by ca. 50% partial melting of the juvenile basaltic crust. The primary magma experienced intensive frac- tionational crystallization, and intruded into the middle to upper crusts to form the granite pluton. In combination with the previous regional geological data, it is concluded that the plagiogranite pluton was emplaced within the Tarim Block in respond to the Carboniferous continental rifting along the Tianshan orogenic belt.  相似文献