Modular and predictable assembly of porous organic molecular crystals

Nanoporous molecular frameworks are important in applications such as separation, storage and catalysis. Empirical rules exist for their assembly but it is still challenging to place and segregate functionality in three-dimensional porous solids in a predictable way. Indeed, recent studies of mixed crystalline frameworks suggest a preference for the statistical distribution of functionalities throughout the pores rather than, for example, the functional group localization found in the reactive sites of enzymes. This is a potential limitation for 'one-pot' chemical syntheses of porous frameworks from simple starting materials. An alternative strategy is to prepare porous solids from synthetically preorganized molecular pores. In principle, functional organic pore modules could be covalently prefabricated and then assembled to produce materials with specific properties. However, this vision of mix-and-match assembly is far from being realized, not least because of the challenge in reliably predicting three-dimensional structures for molecular crystals, which lack the strong directional bonding found in networks. Here we show that highly porous crystalline solids can be produced by mixing different organic cage modules that self-assemble by means of chiral recognition. The structures of the resulting materials can be predicted computationally, allowing in silico materials design strategies. The constituent pore modules are synthesized in high yields on gram scales in a one-step reaction. Assembly of the porous co-crystals is as simple as combining the modules in solution and removing the solvent. In some cases, the chiral recognition between modules can be exploited to produce porous organic nanoparticles. We show that the method is valid for four different cage modules and can in principle be generalized in a computationally predictable manner based on a lock-and-key assembly between modules.     

反应堆保护系统紧急停堆响应时间测试分析

反应堆保护系统的响应时间是核电厂安全级数字化仪表控制系统的关键性能指标.为确保核电厂的安全,提高反应堆保护系统响应时间测量准确性和快速性,通过对反应堆保护系统各大数据处理环节的特点,构建了反应堆保护系统紧急停堆响应时间测试平台,采用自动测试装置对响应时间测试方法进行分析总结,并提出了优化反应堆保护系统紧急停堆响应时间的...     

海藻糖对银杏叶过氧化物酶活性的影响

对银杏叶过氧化物酶热稳定性、最适pH值及海藻糖对酶热稳定性的保护作用和pH值的影响进行了初步研究.结果表明,用40℃和50℃分别处理30 min,过氧化物酶活性分别剩余78%和39%,在60,70,80℃下活性可分别维持27,18和3 min.银杏叶过氧化物酶最适pH值为6.4和9.2.加入海藻糖后酶活性略有降低(活性丧失约8%),但加热后海藻糖的保护优势得以显现,海藻糖浓度为0.14 mol/L时保护效果最好,而且不同温度处理下酶活的下降趋势均较对照组缓慢,尤其在50,60,70℃条件下,相比对照组高出12%~27%的活性,加热时间长短对海藻糖的保护效果无太大影响.经0.14 mol/L浓度的海藻糖处理后,酶活的最适pH值为6.6和9.4.     

基于Petri网的考试系统智能出卷的研究

一般的网络考试系统是从题库中随机选题组卷,容易造成考卷难度不一影响考试的公平性.提出了使用petri网模型,采用启发式随机替换算法来控制考试系统出题难度的解决方案.     

实验室智能排课的研究

针对目前实验室排课的具体情况,提出实现实验室排课的智能化的理论方法.通过分析实验室排课的资源集和约束条件,推导出实验室排课需求集(RCRL),从而提出了一种实验室智能排课的求解算法-AICRL.     

羊栖菜多糖分离纯化和结构的初步鉴定

将提取的羊栖菜多糖用sevage法除蛋白、H2O2脱色后得到羊栖菜多糖半纯品,依次通过DE-AE-52、Sephadex G-200柱层析分离纯化后得到SFPS-B2、SFPS-C1、SFPS-D2三个多糖组分,用Sephacryl S200-HR柱层析鉴定纯度,三种组分的多糖为均一多糖,质量分数分别为86.02%、81.05%、86.95%.对SFPS-D2进行结构初步研究,通过紫外光谱、红外光谱和毛细管电泳分析,结果表明SFPS-D2不含蛋白质和核酸,多糖组成以β构型的吡喃糖苷键为主,含有硫酸基-O-SO3,其单糖组成以木糖、葡萄糖和半乳糖为主,其比例为木糖∶葡萄糖∶半乳糖=3.45∶5.8∶1.     

条形不耦合平面布药技术在硐室爆破中的应用

为了研究条形药包硐室爆破在复杂环境下的应用问题,首先分析了条形药包的作用机理,根据已有硐室爆破平面药包布设的半理论丰经验公式,建立了条形药包平面布设数学模型。并通过工程实例将条形药包布设理论运用于平面布药实践,缩短了平面布设条形药包的设计周期。研究表明,在山体爆破中采用条形不耦合平面布药技术能显著提高有效松动率,降低大块率,减少二次爆破量。同时也减小了爆破振动对周边环境的破坏影响。     

各向异性岩体破坏过程声发射测量及其定位实验研究

应用改进后的声发射设备,实验测量了花岗岩试样在单轴压缩加载条件下变形破坏过程中声发射现象;讨论分析了该试样损伤破坏过程中的诱发微裂纹相互作用、积累等.同时采用对速度结构依赖较少的相对定位方法,对非均质岩石试验中的声发射事件进行了定位研究.结果表明,相对定位方法可用于复杂试样和工程岩体的声发射事件定位,其可靠性及精度比以往有所提高,能够初步定量分析岩石在外载荷作用下的破坏过程的定位问题,对于工程岩体破坏问题分析具有很好的借鉴意义.     

Fabrication of solenoid-type microinductor with different magnetic core schemes by MEMS technique

0 IntroductionThere has been a great demand on micro DC/DCconverter for the applications of the portable electronicproducts such as mobile communication product CDMA(Code Division Multiple Access) ,portable notebookcom-puter ,microprocessor ,digital camcorder andso on.Mag-netic components such as inductors and transformers arethe essential components in constructingthe power supplytransformer ,filter , oscillator , amplifier and micro DC/DCconverter ,andthe miniaturization of inductor an…     

Mutations in CTC1, encoding conserved telomere maintenance component 1, cause Coats plus

Coats plus is a highly pleiotropic disorder particularly affecting the eye, brain, bone and gastrointestinal tract. Here, we show that Coats plus results from mutations in CTC1, encoding conserved telomere maintenance component 1, a member of the mammalian homolog of the yeast heterotrimeric CST telomeric capping complex. Consistent with the observation of shortened telomeres in an Arabidopsis CTC1 mutant and the phenotypic overlap of Coats plus with the telomeric maintenance disorders comprising dyskeratosis congenita, we observed shortened telomeres in three individuals with Coats plus and an increase in spontaneous γH2AX-positive cells in cell lines derived from two affected individuals. CTC1 is also a subunit of the α-accessory factor (AAF) complex, stimulating the activity of DNA polymerase-α primase, the only enzyme known to initiate DNA replication in eukaryotic cells. Thus, CTC1 may have a function in DNA metabolism that is necessary for but not specific to telomeric integrity.