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We synthesized high-quality and oriented periodic mesoporous organosilica (PMO) monoliths through a solvent evaporation process using a wide range of mole ratios of the components: 0.17–0.56 1,2-bis(triethoxysilyl)ethane (BTSE): 0.2 cetyltrimethylammonium chloride (CTACl): 0–1.8 × 10−3 HCl: 0–80 EtOH: 5–400 H2O. X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images indicated that the mesoporous channels within the monolith samples were oriented parallel to the flat external surface of the PMO monolith and possessed a hexagonal symmetry lattice (p6mm). The PMO monolith synthesized from a reactant composition of 0.35 BTSE: 0.2 CTACl: 1.8 × 10−6 HCl: 10 EtOH: 10 H2O had a pore diameter, pore volume, and surface area – obtained from an N2 sorption isotherm – of 25.0 Å, 0.96 cm3 g−1 and 1231 m2 g−1, respectively. After calcination at 280 °C for 2 h in N2 flow, the PMO monolith retained monolith-shape and mesostructure. Pore diameter and surface area of the calcined PMO monolith sample were 19.8 Å, 0.53 cm3 g−1 and 1368 m2 g−1, respectively. We performed 29Si and 13C CP MAS NMR spectroscopy experiments to confirm the presence of Si–C bonding within the framework of the PMO monoliths. We investigated the thermal stability of the PMO monoliths through thermogravimetric analysis (TGA). In addition, rare-earth ions (Eu3+, Tb3+ and Tm3+) were doped into the monoliths. Optical properties of those Eu3+, Tb3+ and Tm3+-doped PMO monoliths were investigated by photoluminescence (PL) spectra to evaluate their potential applicability as UV sensors. 相似文献
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为了研究PMO对GCr15轴承钢连铸坯中MnS夹杂物的影响,首先采用自动扫描电镜(Aspex Explorer)分析脉冲磁致振荡(Pulse Magneto-Oscillation,PMO)技术对钢中MnS类夹杂物组成和形貌的影响,然后利用电子探针测量固液界面前沿的元素含量,并在此基础上,计算了PMO处理后MnS析出温度变化。结果表明,PMO处理促进了内弧1/4、中心和外弧1/4处的大于8 μm的MnS夹杂物数量百分比的降低;PMO处理后固液界面前沿S元素质量分数在试样凝固50%和70%处分别降低60%和36%,而Mn元素含量变化不大;同时,PMO处理可降低MnS夹杂物的析出温度。 相似文献
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Communities-of-practice (CoPs) have received significant attention within a variety of literatures but we remain largely ignorant of the potential of purposefully-created CoPs in global organisations. In this context, the challenge is likely to be convincing ‘masters’ (Wenger, 1998) on the merits of joining the conversation on practice at a distance, thus making the willingness for exchange a key to the quality and longevity of the community. We posed the question “Why would busy, dispersed, knowledgeable professionals want to join and participate in a deliberately-organised CoP?” Our 2-year collaborative action study allowed us to observe the CoP and its membership at close range. We conclude that autonomy, competence and belonging underscore participation, co-production and diffusion of innovative problem-solving and practice beyond the CoP. The study will inform organisations contemplating similar interventions and also serves as a basis for further investigation and theory building on organized CoPs by the research community. 相似文献
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在多项目环境下,传统的专注于单一项目的项目管理理论面临着很多挑战,如项目与组织战略存在脱节,资源无法在众多项目中得到合理分配等。因此,以信息技术为依托的项目群管理理论得到了较大发展。文章在简要介绍项目群管理理论的基础上,根据作者亲历的汽车4S店项目群建设,从实践角度对项目群管理理论进行研究,并在此基础上总结出一些经验。 相似文献
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为了实现电炉厂提产增效的目标,研究了脉冲磁致振荡(PMO)在提高铸坯生产拉速中的应用潜能。结果表明,优化PMO处理参数可以适应生产拉速提高的要求,并改善铸坯的中心偏析和宏观偏析。当连铸拉速提至1.05 m/min,PMO脉冲频率为1.16Kf Hz,峰值电压为1.00KiV处理参数(Kf和Ki分别为仪器的放电频率和电压峰值)时, 铸坯横断面碳偏析指数可控制在1±0.05内;当连铸拉速提至1.15 m/min,PMO脉冲频率为1.28KfHz,峰值电压为1.00KiV处理参数时,铸坯横断面碳偏析指数可控制在1±0.07内。试验证明,在高拉速条件下通过保证单位时间内对钢液施加的脉冲能量可以使连铸坯质量得到有效改善。 相似文献
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简述多项目管理理论,针对铁路扩大建设规模,处于建设高峰期的现状,引入多项目管理方法。分析铁路多项目管理的组织需求,提出一种新的适应铁路建设项目管理的组织模式——PMO多项目管理组织模式,并对其职能、设置和运行中需要注意的问题进行了详细的论述。 相似文献
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介绍了多项目管理框架定义的四个基本分工层次:高层领导团队,项目总的负责人,计划制定部门,项目团队;并分析实施多项目管理面临的问题,引入PMO工具,有效地解决多项目管理的问题,不但摆脱了直线职能型组织应对多项目管理力不从心的尴尬局面,而且还避免了矩阵型组织徘徊于“职能”和“项目”之间的两难境地。 相似文献
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Jasmin Kuhn Philipp M. Klein Nader Al Danaf Joel Z. Nordin Sren Reinhard Dominik M. Loy Miriam Hhn Samir El Andaloussi Don C. Lamb Ernst Wagner Yoshitsugu Aoki Taavi Lehto Ulrich Lchelt 《Advanced functional materials》2019,29(48)
Phosphorodiamidate morpholino oligomers (PMOs) are oligonucleotide analogs that can be used for therapeutic modulation of pre‐mRNA splicing. Similar to other classes of nucleic acid‐based therapeutics, PMOs require delivery systems for efficient transport to the intracellular target sites. Here, artificial peptides based on the oligo(ethylenamino) acid succinyl‐tetraethylenpentamine (Stp), hydrophobic modifications, and an azide group are presented, which are used for strain‐promoted azide‐alkyne cycloaddition conjugation with splice‐switching PMOs. By systematically varying the lead structure and formulation, it is determined that the type of contained fatty acid and supramolecular assembly have a critical impact on the delivery efficacy. A compound containing linolenic acid with three cis double bonds exhibits the highest splice‐switching activity and significantly increases functional protein expression in pLuc/705 reporter cells in vitro and after local administration in vivo. Structural and mechanistic studies reveal that the lipopeptide PMO conjugates form nanoparticles, which accelerate cellular uptake and that the content of unsaturated fatty acids enhances endosomal escape. In an in vitro Duchenne muscular dystrophy exon skipping model using H2K‐mdx52 dystrophic skeletal myotubes, the highly potent PMO conjugates mediate significant splice‐switching at very low nanomolar concentrations. The presented aminoethylene‐lipopeptides are thus a promising platform for the generation of PMO‐therapeutics with a favorable activity/toxicity profile. 相似文献