Mechanical Properties of Graphene Foam and Graphene Foam—Tissue Composites

Graphene foam (GF), a 3‐dimensional derivative of graphene, has received much attention recently for applications in tissue engineering due to its unique mechanical, electrical, and thermal properties. Although GF is an appealing material for cartilage tissue engineering, the mechanical properties of GF‐tissue composites under dynamic compressive loads have not yet been reported. The objective of this study is to measure the elastic and viscoelastic properties of GF and GF‐tissue composites under unconfined compression when quasi‐static and dynamic loads are applied at strain magnitudes below 20%. The mechanical tests demonstrate a 46% increase in the elastic modulus and a 29% increase in the equilibrium modulus after 28‐days of cell culture as compared to GF soaked in tissue culture medium for 24 h. There is no significant difference in the amount of stress relaxation, however, the phase shift demonstrates a significant increase between pure GF and GF that has been soaked in tissue culture medium for 24 h. Furthermore, the authors have shown that ATDC5 chondrocyte progenitor cells are viable on graphene foam and have identified the cellular contribution to the mechanical strength and viscoelastic properties of GF‐tissue composites, with important implications for cartilage tissue engineering.

     

增强现实技术的应用

随着计算机技术的发展,增强现实技术逐渐成为下一代人机接口技术发展的主要方向之一。增强现实技术使用户可以容易地进入人们本来不能进入的微观世界,以及人们不能直接进入的特殊环境,并为人们的研究工作构造理想的交互环境,比如观察分子立体结构、探索基因芯片本质的增强现实系统等。增强现实技术与计算机图形学、人机交互技术、网络多媒体技术相结合,广泛应用于医学、军事、工业、娱乐等方面。     

Development of an approach for generation of temporally complete daily nadir MODIS reflectance time series

Consistent, spatially and temporally complete reflectance time series are required for reliable terrestrial monitoring. The Moderate Resolution Imaging Spectroradiometer (MODIS), like other polar-orbiting wide field of view satellite sensors, can provide global observations on a nearly daily basis, but the sparseness of valid observations due to cloud, residual atmospheric effects, and sensor anomalies, may result in gaps in the derived reflectance time series. This paper presents an approach for the generation of temporally complete daily MODIS 500 m nadir view BRDF-adjusted reflectance (NBAR) time series. The research is illustrated and assessed quantitatively using two years of cloud and snow screened, daily MODIS Terra and Aqua reflectance data at four sites in Africa, and demonstrated for phenology monitoring using NBAR derived NDVI time series. The components of the approach include: 1) an outlier detection algorithm to remove residual anomalous daily observations undetected in the upstream processing, 2) the dynamic generation of NBAR time series on a daily basis when seven or more observations are available for a day under consideration over a 16-day period, and 3) the means to gap fill the NBAR time series where less than 7 observations are available. The MODIS Ross-Thick/Li-Sparse-Reciprocal BRDF model is used with a rolling approach whereby a 16-day BRDF inversion window is moved on a daily overlapping basis to provide more reliable outlier detection and daily NBAR. NBAR gap filling in periods of missing observations is investigated using static land cover specific archetype BRDF parameters and using BRDF parameters defined adaptively from the temporally closest 16-day periods with 7 or more observations. Scaling factor estimators using ordinary least squares (OLS) and median-based robust least squares regression are investigated, and the robust method is demonstrated to provide on average temporally more coherent gap filled NBAR values. For regions with persistent clouds, the utility of the adaptive NBAR gap filling method is demonstrated to be severely limited due to the decreased likelihood that the surface BRDF at each gap can be described reliably. The reliability of the NBAR gap filling methodology is evaluated statistically using a cross-validation approach. For the small number of study site considered, the adaptive method is shown to provide more accurate results than the archetype method when there are more than an average of ~ 4-5 observations per 16-day window, or when a gap day is on average less than about 30 days from a 16-day period with 7 or more observations. The resulting gap free daily NBAR time series and derived daily NBAR NDVI generated by the approach is shown to capture phenological variations in a coherent temporally consistent manner, suggesting that it is a fruitful avenue for future research and validation.     

金刚石锯片激光焊接

研究了焊接工艺参数及刀头材料对焊接质量的影响。结果表明 ,激光功率、焊接速度、离焦量、光束偏移量等工艺参数显著影响焊接质量 ;刀头材料的成分对焊接质量也有很大影响     

Developing as a therapist: Stress-related growth through parenting a child in crisis.

Stress-related growth following a variety of highly stressful experiences is receiving increased attention. However, one area that has not yet been addressed is the growth that therapists may experience in their own personal life through encounters with trauma and personal struggles and how this growth might carry forward to the work that they do with their clients in the practice of psychotherapy. In the present article, the authors describe stress-related growth and use it as a framework to examine the stressful experience and ultimate growth of a therapist dealing with a family member's emotional crises. Three areas of her growth as a therapist are examined: strengthened understanding of the therapeutic process from the client's viewpoint, additional strategies for approaching the change process, and increased empathy for parents and clients. The article concludes with recommendations for therapists experiencing personal struggles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review of Strategies for building multicultural competence in mental health and educational settings.

Reviews the book, Stategies for building multicultural competence in mental health and educational settings edited by M. G. Constantine and D. W. Sue (2005). Strategies for Building Multicultural Competence in Mental Health and Educational Settings is an excellent resource designed for mental health professionals who may lack knowledge and expertise in working with diverse clients. It provides hands-on strategies and suggestions in a variety of contexts, using the Multicultural Guidelines as a framework. This book is strongly recommended for clinicians working with culturally diverse populations. The Surgeon General's report Mental Health: Culture, Race and Ethnicity (U.S. Department of Health & Human Services, 2001) clearly demonstrates the disparity in the mental health care of racial and ethnic minorities as compared with Whites. This book is useful not only to novices exploring diversity but also to those who are already cross-culturally competent. The authors successfully apply the APA Multicultural Guidelines in clinical practice and educational, training, and organizational settings while providing specific strategies for clinicians. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Construction and characterization of hexon-chimeric adenoviruses: specification of adenovirus serotype

This study has used the strategy of gene replacement to characterize the contribution of the adenovirus (Ad) capsid protein hexon to serotype definition. By replacing the Ad type 5 (Ad5) hexon gene with sequences from Ad2, we have changed the type specificity of the chimeric virus. The type-determining epitopes are primarily associated with loop 1 of hexon and, to a much lesser degree, with loop 2. In spite of the serotype distinctiveness of the chimeric hexon viruses, epitope similarity between the vectors resulted in a low level of cross-reactive neutralizing antibody, which in combination with activated cellular and innate arms of the immune system is sufficient to suppress gene transduction following readministration in vivo.     

Two-photon absorption effect and the intra-molecular charge transfer of p-substituted stilbene-type pyridinium salts

The relationships between two-photon absorption (TPA) effect and excited state intramolecular charge transfer (ICT) of p-substituted stilbene-type pyridinium salts have been investigated. Two-photon absorption cross section (δTPA) for all the compounds has been determined by open aperture Z-scanning technique, while two-photon pumped (TPP) up-converted lasing efficiencies (η) and optical limiting behavior have been measured by two-channel energy-meter, pumped by a mode locked Nd: YAG ps laser. Streak camera was used to record two-photon induced fluorescence and the fluorescence lifetimes. The experimental and calculated results have shown that the excited state larger in-tra-molecular charge transfer, in the excited state characterized by the charge density difference between the ground state ( S0) and the first excited state ( S1), has contributed to enhancing TPA cross section and may result in better optical limiting effect. And high TPP up-converted lasing efficiency is related to not only the δTP     

Laboratory methods for assessing API sensitivity to mechanical stress during agitated drying

Two distinct laboratory methods have been developed to assess the propensity of active pharmaceutical ingredients to undergo particle breakage during agitated drying operations. In the first method, mechanical stress is applied to particles by mechanical agitation of powders compressed under an applied normal force. For the second, particles experience stresses as they are carried within a pressurized gas stream. These methods are simple, relatively compound-sparing, and are used to rank materials according to a quantitative breakage classification scale as hard, medium, or easy to break. Based on the results obtained using these methods at laboratory scale, recommendations and precautions for processing at larger scale are made. In this paper, these methods are described in detail, and the results, obtained for several pharmaceutical compounds, are presented.