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排序方式: 共有887条查询结果,搜索用时 15 毫秒
881.
秦兵马俑博物馆陶器库房冬季室内空气质量初步研究 总被引:1,自引:0,他引:1
于2008年1月30日~3月3日,在秦始皇兵马俑博物馆陶器库开展了室内大气环境调查,同步采集了大气悬浮颗粒PM2.5和NH3样品,获得了PM2.5颗粒中的离子组成,并实时监测了SO2、NOx的浓度变化。结果表明,陶器库中PM2.5平均质量浓度为76.1μg/m3,室外PM2.5平均质量浓度为153.9μg/m3,约为室内浓度的2倍。室内PM2.5中水溶性离子主要由SO42-、NO3-和NH4+组成,平均质量浓度分别为17.5、5.2、5.5μg/m3,它们分别占PM2.5质量浓度的19.7%、5.2%、5.8%。库内NH3平均浓度为4.8μg/m3,室外NH3平均浓度6.6μg/m3,约为室内的1.4倍。室内NO、NO2、NOx浓度日平均分别为4.8×10-9、3.2×10-9、8.0×10-9,SO2浓度日平均为0.9×10-9。研究表明,库内人为活动量对质量浓度、离子浓度和污染气体均有一定影响,库房相对于室外对阻挡颗粒物减少外界影响方面对文物有一定的保护作用,但在阻隔空气污染物和恒温恒湿方面的作用还有待加强。 相似文献
882.
Junji Akimoto Tadayoshi Akao Kunimitsu Kataoka 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(40):2301617
Garnet-type Li7La3Zr2O12 (LLZ) materials are attracting attention as solid electrolytes (SEs) in oxide-based all-solid-state batteries (ASSBs) owing to their high ionic conductivity. Although the electrochemical stability of LLZ against Li metal is demonstrated with possible high energy density, high-temperature sintering above 1000 °C, which is required to achieve high Li-ion conductivity, results in the formation of insulating impurities at the electrode–electrolyte interfaces. Here, nanosized fine-particle samples of Ta-substituted Li6.5La3Zr1.5Ta0.5O12 (LLZT) are successfully prepared at a remarkably low temperature of 400 °C utilizing an amorphous precursor oxide. The dense LLZT SE sintered by hot pressing at 500 °C shows room-temperature Li-ion conductivity of 1.03 × 10−4 S cm−1 without any additives. In addition, the bulk-type NCM–graphite full battery cell fabricated with the LLZT fine particles through a hot-pressing sintering method at 550 °C exhibits a good charge–discharge performance at room temperature with the bulk-type areal discharge capacity of 0.831 mAh cm−2. The nanosized garnet SE strategy demonstrated in this study paves the way for the formation of oxide-based ASSBs by low-temperature sintering. 相似文献
883.
Masaya Fujioka Melbert Jeem Kento Sato Masashi Tanaka Kazuki Morita Taizo Shibuya Kiyonori Takahashi Suguru Iwasaki Akira Miura Masanori Nagao Satoshi Demura Hideaki Sakata Madoka Ono Hideo Kaiju Junji Nishii 《Advanced functional materials》2023,33(10):2208702
Intercalation into 1D transition metal trichalcogenides (TMTs) in which fibers are bonded by a weak van der Waals force can be expected to create various intercalation compounds and develop unique physical properties according to the combination of the host materials and guest ions. However, structural changes via intercalation into 1D TMTs are not as simple as those in 2D transition metal dichalcogenides (TMDs) and are still not understood comprehensively. ZrTe3: a typical compound with a 1D trigonal prismatic structure, belongs to TMTs. Herein, through the Ag introduction to ZrTe3 via solid-state intercalation, a novel crystal phase with a 1D octahedral structure and a quasi-amorphous (QA) phase during the structural transition are discovered; the QA phase is a novel state of matter in which long-range order is lost while retaining 1D order. Based on the Ag concentration, the transport properties are flexibly modulated from superconductivity to semiconductivity. Density functional theory calculations indicate the attraction between Ag ions and the pair diffusion due to their attraction. Furthermore, judging the attraction or repulsion between guest ions predicts whether to induce a QA phase or simple lattice expansion like the intercalation into 2D TMDs. 相似文献
884.
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886.
Prof. Dr. Fumitaka Kudo Kosuke Kishikawa Kazuma Tsuboi Takafusa Kido Prof. Dr. Takeo Usui Dr. Junko Hashimoto Prof. Dr. Kazuo Shin-ya Prof. Dr. Akimasa Miyanaga Prof. Dr. Tadashi Eguchi 《Chembiochem : a European journal of chemical biology》2023,24(6):e202200670
Streptomyces graminofaciens A-8890 produces two macrolide antibiotics, FD-891 and virustomycin A, both of which show significant biological activity. In this study, we identified the virustomycin A biosynthetic gene cluster, which encodes type I polyketide synthases (PKSs), ethylmalonyl-CoA biosynthetic enzymes, methoxymalony-acyl carrier protein biosynthetic enzymes, and post-PKS modification enzymes. Next, we demonstrated that the acyltransferase domain can be exchanged between the Vsm PKSs and the PKSs involved in FD-891 biosynthesis (Gfs PKSs), without any supply problems of the unique extender units. We exchanged the malonyltransferase domain in the loading module of Gfs PKS with the ethylmalonyltransferase domain and the methoxymalonyltransferase domain of Vsm PKSs. Consequently, the expected two-carbon-elongated analog 26-ethyl-FD-891 was successfully produced with a titer comparable to FD-891 production by the wild type; however, exchange with the methoxymalonyltransferase domain did not produce any FD-891 analogs. Furthermore, 26-ethyl-FD-891 showed potent cytotoxic activity against HeLa cells, like natural FD-891. 相似文献
887.