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31.
The Middle Pliocene (ca 3.12–2.97 Ma) is a recent warm period in the Earth’s history. In many respects, the warmth of the Middle Pliocene is similar to the probable warm situation of the late 21st century predicted by climate models. Understanding the Middle Pliocene climate is important in predicting the future climate with global warming. Here, we used the latest reconstructions for the Middle Pliocene—Pliocene Research Interpretation and Synoptic Mapping (PRISM) version 3—to simulate the Middle Pliocene ... 相似文献
32.
采用聚丙烯酰胺(PAM)为软模板,在CuSO4、Na2SO3体系中调控合成了片状、海胆状、一维线、针状聚集体氧化亚铜晶体。研究了不同浓度Cu2+、不同PAM含量及不同温度对晶体生长的影响。结果表明,PAM促使氧化亚铜异相成核,氧化亚铜形貌随PAM质量分数的变化而变化:当c(Cu2+)=0.5mol.L-1时,PAM质量分数为3.0%(常温引入体系),产物主要为片状晶体;PAM质量分数为1.0%、3.0%时(高温引入体系),分别获得一维线状、海胆状晶体;当Cu2+浓度为0.1 mol.L-1时,体系中高温引入质量分数3.0%的PAM,得到片层状晶体;当Cu2+浓度为0.3、0.4 mol.L-1时,得到针状聚集体氧化亚铜晶体。分别用X射线粉末衍射、冷场发射扫描电子显微镜和激光粒度仪对所制备的产品进行了表征。 相似文献
33.
S. Cint Pinzaru Cs. Müller S. Tomi M. M. Venter B. I. Cozar B. Glamuzina 《Journal of Raman spectroscopy : JRS》2015,46(7):597-604
While recording SERS spectra of pure β‐carotene at sub‐micromole concentrations for reference purpose, we discovered an unusual spectral response never reported before. In pre‐resonance conditions with the 532‐nm line, SERS of β‐carotene with AgNPs exhibits among the strong υ(CC) mode at 1512 cm−1 unshifted from normal Raman spectrum, additional strong bands at 1649, 1575 and 1387 cm−1 as well as other medium bands not observed in the Raman spectrum of the crystalline powder. Such behavior is explained in terms of selection rules relaxation upon cyclohexene terminal rings of the β‐carotene interaction with the NP surface. AFM images of the SERS system suggested dimers and trimers clustering of the nanoparticles with adsorbed β‐carotene. In light of the new SERS feature the consequences in correct interpretation of the SERS imaging from complex biosystems containing carotenoids are discussed. Relative intensity ratio of the β‐carotene band at 1512 cm−1 and water against concentration allowed a reliable SERS calibration curve for 50 to 500 nmol l−1 concentration range and provided quantitative SERS assessment of the carotenoid content in the sea urchin (Paracentrotus lividus) gonads extracts. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
34.
Dorota Najgebauer-Lejko Katarzyna Liszka Magorzata Tabaszewska Jacek Domagaa 《Molecules (Basel, Switzerland)》2021,26(8)
Elderberries, sea buckthorn, and sloe berries are fruits of wild-grown bushes, valued in folk medicine for their health-promoting properties but still rarely applied in food. The aim of the present study was to produce probiotic yoghurts with a 10% addition of sweetened purees prepared from elderberries (EPY), sea buckthorn (SBPY), and sloe berries (SPY) and to assess their chemical composition, acidity, content of polyphenols and anthocyanins, ferric reducing antioxidant power (FRAP) and antiradical power (ARP), level of starter microbiota, concentration of acetaldehyde and diacetyl, syneresis, instrumentally measured color and texture parameters, and sensory acceptance. The results were compared to those obtained for plain probiotic yoghurt (PPY) and the changes tracked during 1 month of cold storage at 2 week intervals. The addition of elderberry and sloe berries significantly increased the antioxidant capacity of probiotic yoghurts, probably due to a high content of polyphenols, especially anthocyanins. However, anthocyanins were more stable in the EPY when compared to the SPY. All yoghurt treatments were characterized by good sensory quality and viability of starter microorganisms, including probiotic strains during cold storage. Elderberries promoted the evolution of diacetyl in yoghurts during storage and, together with sloe berries, produced increased syneresis and the greatest changes in color profile compared to PPY. 相似文献
35.
Wang LiBo Yang ZuoSheng ZHang RongPing Fan DeJiang Zhao MeiXun Hu BangQi 《科学通报(英文版)》2011,56(15):1588-1595
Sea surface temperature (SST) records in the South Yellow Sea during the last 6200 years are reconstructed by the unsaturation index of long-chain alkenones (K 37 U ’) in sediment core ZY2 from the central mud area.The SST records varied between 14.1 and 16.5°C (15.6°C on average),with 3 phases:(1) A high SST phase at 6.2-5.9 cal ka BP;(2) A low and intensely fluctuating SST phase at 5.9-2.3 cal ka BP;and (3) A high and stable SST phase since 2.3 cal ka BP.Variation of the SST records is similar to intensity of the Kuroshio Current (KC),and corresponds well in time to global cold climate events.However,the amplitude of the SST response to cooling events was significantly different in different phases.The SST response to global cooling event was weak while the KC was strong;and the SST response was strong while the KC was weak.The difference in amplitude of the SST response is possibly caused by the modulation effect of the Yellow Sea Warm Current which acts as a shelf branch of the KC and a compensating current induced by the East Asia winter monsoon.The warm waters brought by the Yellow Sea Warm Current cushion the SST decrease induced by climate cooling,and both the Kuroshio and East Asian winter monsoon play important roles in the modulation mechanism.The SST records display a periodicity of 1482 years.The same period was found in the KC records,indicating that variation of the SST records in the central South Yellow Sea is strongly affected by KC intensity.The same period was also found in Greenland ice cores and North Atlantic and Arabian Sea sediment cores,showing a regional response of marine environmental variability in the East China Seas to that in the global oceans. 相似文献
36.
研究两种不同特性工业废渣铁尾矿、粉煤灰对海泥烧结多孔砖样品泛霜程度的影响及机理.结果表明:铁尾矿减轻海泥烧结砖泛霜程度的有利因素多,粉煤灰提高海泥烧结砖泛霜程度的不利因素多.此外,掺加外加剂可以在某种程度上降低海泥烧结砖的泛霜等级;当掺量达到某一范围时,能够较大幅度减少砖坯成型用水量,烧成中产生液相的非瘠性工业废渣-铁... 相似文献
37.
Sea surface temperature east of Australia: A predictor of tropical cyclone frequency over the western North Pacific? 总被引:7,自引:1,他引:6
The relationship between sea surface temperature (SST) east of Australia and tropical cyclone frequency over the western North Pacific (WNPTCF) is analyzed by use of observation data.The WNPTCF from June to October is correlated negatively to spring SST east of Australia.When the spring SST is in the positive phase,a cyclonic circulation anomaly in the upper troposphere and an anticyclonic circulation anomaly in the lower troposphere prevail over the western North Pacific from June to October,concurrent with an anomalous atmospheric subsidence and an enlarged vertical zonal wind shear.These conditions are unfavorable for tropical cyclone genesis,and thus WNPTCF decreases.The negative phase of the spring SST east of Australia leads to more tropical cyclones over the western North Pacific.The spring SST east of Australia may give rise to simultaneous change in tropical atmospheric circulation via the teleconnection wave train,and then subsequently affect atmospheric circulation variation over the western North Pacific. 相似文献
38.
Philippe Savarino Emmanuel Colson Guillaume Caulier Igor Eeckhaut Patrick Flammang Pascal Gerbaux 《Molecules (Basel, Switzerland)》2022,27(2)
Saponins are plant and marine animal specific metabolites that are commonly considered as molecular vectors for chemical defenses against unicellular and pluricellular organisms. Their toxicity is attributed to their membranolytic properties. Modifying the molecular structures of saponins by quantitative and selective chemical reactions is increasingly considered to tune the biological properties of these molecules (i) to prepare congeners with specific activities for biomedical applications and (ii) to afford experimental data related to their structure–activity relationship. In the present study, we focused on the sulfated saponins contained in the viscera of Holothuria scabra, a sea cucumber present in the Indian Ocean and abundantly consumed on the Asian food market. Using mass spectrometry, we first qualitatively and quantitatively assessed the saponin content within the viscera of H. scabra. We detected 26 sulfated saponins presenting 5 different elemental compositions. Microwave activation under alkaline conditions in aqueous solutions was developed and optimized to quantitatively and specifically induce the desulfation of the natural saponins, by a specific loss of H2SO4. By comparing the hemolytic activities of the natural and desulfated extracts, we clearly identified the sulfate function as highly responsible for the saponin toxicity. 相似文献
39.
GC法测定青岛某水体中雌激素含量 总被引:10,自引:0,他引:10
介绍了测定环境水中几种雌激素,如:雌酮(E1)、雌二醇(E2)、雌三醇(E3)和雌炔醇(EE2)的测定方法.用C-18小柱对水体中的雌激素进行富集.研究了用TFA、MSTFA对雌激素的衍生化条件.GC-FID及GC-MS法测定衍生化雌激素的工作曲线,相关系数在0.98~0.99之间.测得500 mL实际水样中的加标回收率为86%~120%.5 000 mL环境水样的方法检测限为1~3 ng/L.用GC-MS法测定了海水和河水中的雌激素含量. 相似文献
40.