超微孔SiO_2负载Pt催化剂的合成、表征与催化苯乙炔硅氢加成性能

以超微孔二氧化硅为载体,制备了负载的铂胶体催化剂,用液氮吸附-脱附,FT-IR,ICP,UV-solid等技术对催化剂进行了表征。在微波反应器中将催化剂用于催化苯乙炔与甲基氢二氯硅烷硅氢加成反应,结果显示该催化剂有很高的催化活性和重复实用性。无溶剂、100℃下反应0.5h,甲基氢二氯硅烷的平均转化率可达96.61%,区域选择性β-(E)加成产物大于99.50%。催化剂性能稳定,回收使用5次无明显失活。

Assessing the impact of TB/HIV services integration on TB treatment outcomes and their relevance in TB/HIV monitoring in Ghana

Background:The impact of the human immunodeficiency virus(HIV)on tuberculosis(TB),and the implications for TB and HIV control,is a public health challenge in Ghana-almost a quarter(23%)of all TB cases were HIV positive in 2010.The integration of TB/HIV services has therefore emerged as an essential component of the national response to TB and HIV.The aim is to reduce fragmentation,improve access,enhance efficiency and improve quality of care.Ghana’s TB/HIV policy comprises three linked sets of activities:effective implementation of the Stop TB Strategy for TB control,improved HIV prevention and care,and the implementation of additional TB/HIV activities.Different models of service delivery with increasing integration of TB/HIV activities are expected to provide greater access to more comprehensive care.The objective of this paper is to assess the impact of TB/HIV integration on TB treatment outcomes and to explore the usefulness of TB treatment outcomes as TB/HIV indicators.Methods:A before-and-after study to observe the introduction of TB/HIV activities into TB programmes in three hospitals with different levels of integration was conducted.Anonymised patient data was collated from TB registers from each facility,and analysed to determine if TB treatment outcomes changed significantly after integration.Results:TB treatment success was 50%(95%CI 49-52)prior to,and 69%(95%CI 65-73)after,integration(Χ243.96,p<0.00).Treatment success increased from 43%to 53%at the one-stop shop(OSS),from 69%to 78%at the partially integrated site(PIS)and substantially from 46%to 78%at the referral site(RS)(Χ264.54;p<0.01).Defaults and cases transferred out reduced from 14.3%and 15.3%prior to integration,to 1.4%and 9.0%after integration,respectively,accounting for a significant increase in treatment success.Death rates remained high at 18%in all cases studied and 25%in HIV-associated cases after integration.Conclusion:TB/HIV integration may improve TB treatment success,but its exact impact is difficult to ascertain due to non-specificity and design limitations.TB mortality may be more useful as an indicator for monitoring TB/HIV activities in Ghana.

Room Temperature Ferromagnetism in Ga1-xHoxN （x=0.0 and 0.05） Diluted Magnetic Semiconductor Thin Films

Holmium doped GaN diluted magnetic semiconductor thin films have been prepared by thermal evaporation technique and subsequent ammonia annealing. X-ray diffraction mea- surements reveal all peaks belong to the purely hexagonal wurtzite structure. Surface mor- phology and composition analysis were carried out by scanning electron microscopy and energy dispersive spectroscopy respectively. The room temperature ferromagnetic proper- ties of Gal-xHoxN （x=0.0, 0.05） films were analyzed using vibrating sample magnetometer at room temperature. Magnetic measurements showed that the undoped films （i.e. GaN） exhibited diamagnetic behavior, while the Ho-doped （Gao.95Hoo.05N） film exhibited a ferro- magnetic behavior.

Development of a sample preparation approach to measure the size of nanoparticle aggregates by electron microscopy

Electron microscopy (EM) is widely used for nanoparticle (NP) sizing. Following an initial assessment of two sample preparation protocols described in the current literature as"unperturbed", we found that neither could accurately measure the size of NPs featuring a broad size distribution, e.g., aggregates. Because many real-world NP samples consist of aggregates, this finding was of considerable concern. The data showed that the protocols introduced errors into the measurement by either inducing agglomeration artefacts or providing a skewed size distribution towards small particles (skewing artefact). The focus of this work was to develop and apply a mathematical refinement to correct the skewing artefact. This refinement provided a much improved agreement between EM and a reference methodology, when applied to the measurement of synthetic amorphous silica NPs. Further investigation, highlighted the influence of NP chemistry on the refinement. This study emphasised the urgent need for greater and more detailed consideration regarding the sample preparation of NP aggregates to routinely achieve accurate measurements by EM. This study also provided a novel refinement solution applicable to the size characterisation of silica and c让rate-coated gold NPs featuring broad size distributions. With further research, this approach could be extended to other NP types.

Using Conversation Analysis to Study Gender:An alternative to the ‘gender-differences’ paradigm

Research on gender and language has typically been underpinned by the premise that women and men are essentially different,and that these differences are evident in how they talk.In this paper,I introduce—and argue in favour of—the conversation analytic(CA)approach to gender as an alternative to a gender-differences paradigm.I describe what I take to be the three main challenges that conversation analysts have levied against such an approach,which I summarise as:a question of evidence,a question of relevance,and a question of existence(or ontology).I then describe,and critically evaluate,the classic solution to these questions that conversation analysts have proposed:a focus on‘participant orientations’to gender.I suggest that—in addition to correcting some of the mistaken analyses of interactional phenomena evident in gender-differences research—CA can inspire new ways of thinking about old research questions.I also propose that the question of what counts as an orientation to gender and,relatedly,how best to analyse the taken-for-granted social world,provide particularly fruitful areas for future research.I conclude by calling on researchers and students of gender to avoid using the assumption of essential difference as the starting point for academic endeavour.

地方政府债券发行期限影响因素--基于投资者信息不对称视角

本文以债券投资者视角,运用信息不对称理论和委托-代理理论从区域经济特征、地方政府综合财力和债券发行要素三个方面分析提炼出影响地方政府债券发行期限的因素,并以2011~2018年我国省级地方政府发行的3923只债券为样本,构建了Lasso-Logistic模型,实证分析了在不同经济发展水平①下这些因素的影响情况。研究结果表明:在东部地区提升固定资产投资率不利于长期限地方政府债券的发行,在中部和西部地区提升固定资产投资率有助于长期限地方政府债券的发行,而在东北地区,固定资产投资率变动对地方政府债券发行期限没有影响。地方政府综合财力越强,越有助于长期限地方政府债券的发行。通过合理设置地方政府债券的发行条款,也能促进长期限地方政府债券发行。

Biquadratic exchange interactions in two-dimensional magnets

Magnetism in recently discovered van der Waals materials has opened several avenues in the study of fundamental spin interactions in truly two-dimensions.A paramount question is what effect higher-order interactions beyond bilinear Heisenberg exchange have on the magnetic properties of few-atom thick compounds.Here we demonstrate that biquadratic exchange interactions,which is the simplest and most natural form of non-Heisenberg coupling,assume a key role in the magnetic properties of layered magnets.Using a combination of nonperturbative analytical techniques,non-collinear first-principles methods and classical Monte Carlo calculations that incorporate higher-order exchange,we show that several quantities including magnetic anisotropies,spin-wave gaps and topological spin-excitations are intrinsically renormalized leading to further thermal stability of the layers.

Multiparameter resonant imaging for studying cell interactions

The development of optical microscopy techniques has provided major insights into the machinery of life,from molecules to cells to tissues and organs.Fluorescent techniques have been particularly successful in this respect by elucidating biological pathways and helping us understand the complex relationships that underpin all living organisms.For example,the first use of fluorescence as an analytical tool in 18641 paved the way for the study of biological entities and interactions,but it was not until nearly 60 years later,in the 1930s,that fluorophores were first employed to perform biological investigations into specific tissue components and bacteria that do not autofluoresce2.These advances led to the first labeling of an antibody with a visible label in 19413,which gave birth to the field of immunofluorescence and allowed us obtain unprecedented insight into antibody structure.

Relativistic domain-wall dynamics in van der Waals antiferromagnet MnPS_(3)

The discovery of two-dimensional(2D)magnetic van der Waals(vdW)materials has flourished an endeavor for fundamental problems as well as potential applications in computing,sensing and storage technologies.Of particular interest are antiferromagnets,which due to their intrinsic exchange coupling show several advantages in relation to ferromagnets such as robustness against external magnetic perturbations.Here we show that,despite of this cornerstone,the magnetic domains of recently discovered 2D vdW MnPS_(3)antiferromagnet can be controlled via magnetic fields and electric currents.We achieve ultrafast domain-wall dynamics with velocities up to~3000 m s^(−1)within a relativistic kinematic.Lorentz contraction and emission of spin-waves in the terahertz gap are observed with dependence on the edge termination of the layers.Our results indicate that the implementation of 2D antiferromagnets in real applications can be further controlled through edge engineering which sets functional characteristics for ultrathin device platforms with relativistic features.