Calibration, Error Analysis, and Ongoing Measurement Process Monitoring for Mass Spectrometry

We consider problems of quantifying and monitoring accuracy and precision of measurement in mass spectrometry, particularly in contexts where there is unavoidable day-to-day/period-to-period changes in instrument sensitivity. First, we consider the issue of estimating instrument sensitivity based on data from a typical calibration study. Simple method-of-moments methods, likelihood-based methods, and Bayes methods based on the one-way random effects model are illustrated. Then, we consider subsequently assessing the precision of an estimate of a mole fraction of a gas of interest in an unknown. Finally, we turn to the problem of ongoing measurement process monitoring and illustrate appropriate setup of Shewhart control charts in this application.     

Formation of MgO-B4C Composite via aThermite-Based Combustion Reaction

The combustion synthesis of MgO-B₄C composites was investigated by coupling a highly exothermic Mg-B₂O₃ thermite reaction with a weakly exothermic B₄C formation reaction. Unlike the case of using Al as the reducing agent, the interaction between Mg and B₂O₃ depends on the surrounding inert gas pressure due to the high vapor pressure of Mg. The interaction changes from one involving predominantly gaseous Mg and liquid B₂O₃ to one involving liquid Mg and liquid B₂O₃ as the pressure increases. At low inert gas pressure, the initiation temperature is found to be just below the melting point of Mg (650°C). As the inert gas pressure increases, the vaporization loss of reactants is reduced, and this in turn increases the combustion temperature, which promotes greater grain growth of the product phases, MgO and B₄C. The particle size of B₄C increased from about 0.2 to 5 μm as the pressure changed from 1 to 30 atm.     

Controllable fabrication of tube-in-tubes using anodic aluminum oxide templates

We have developed a method to fabricate tube-in-tubes that are relatively long and made in all the pores of porous anodic aluminum oxide (AAO) nano-templates. Relatively a very small amount of Co was deposited in the pores of AAO templates prepared without doing a voltage drop at the end of anodization, and then etched in NaOH solution. This caused the carbon nanotubes (CNTs) to grow out from all the pores, and larger diameter carbon nanotubes were also made on the inner surface of all the pores, by forming tube-in-tubes. We were able to control the gap between the inner surface of the larger tubes and the outer surface of the smaller ones of tube-in-tubes in some range by changing the etching time in NaOH solution. Tube-in-tubes that are relatively long and controlled the gap could be used as a storage, particularly for hydrogen gas.     

Bio‐Orthogonally Crosslinked,Engineered Protein Hydrogels with Tunable Mechanics and Biochemistry for Cell Encapsulation

Covalently‐crosslinked hydrogels are commonly used as 3D matrices for cell culture and transplantation. However, the crosslinking chemistries used to prepare these gels generally cross‐react with functional groups present on the cell surface, potentially leading to cytotoxicity and other undesired effects. Bio‐orthogonal chemistries have been developed that do not react with biologically relevant functional groups, thereby preventing these undesirable side reactions. However, previously developed biomaterials using these chemistries still possess less than ideal properties for cell encapsulation, such as slow gelation kinetics and limited tuning of matrix mechanics and biochemistry. Here, engineered elastin‐like proteins (ELPs) are developed that crosslink via strain‐promoted azide‐alkyne cycloaddition (SPAAC) or Staudinger ligation. The SPAAC‐crosslinked materials form gels within seconds and complete gelation within minutes. These hydrogels support the encapsulation and phenotypic maintenance of human mesenchymal stem cells, human umbilical vein endothelial cells, and murine neural progenitor cells. SPAAC‐ELP gels exhibit independent tuning of stiffness and cell adhesion, with significantly improved cell viability and spreading observed in materials containing a fibronectin‐derived arginine‐glycine‐aspartic acid (RGD) domain. The crosslinking chemistry used permits further material functionalization, even in the presence of cells and serum. These hydrogels are anticipated to be useful in a wide range of applications, including therapeutic cell delivery and bioprinting.     

Trinity: Walking on a User-Object-Tag Heterogeneous Network for Personalised Recommendations

The rapid evolution of the Internet has been appealing for effective recommender systems to pinpoint useful information from online resources. Although historical rating data has been widely used as the most important information in recommendation methods, recent advancements have been demonstrating the improvement in recommendation performance with the incorporation of tag information. Furthermore, the availability of tag annotations has been well addressed by such fruitful online social tagging applications as CiteULike, MovieLens and BibSonomy, which allow users to express their preferences, upload resources and assign their own tags. Nevertheless, most existing tag-aware recommendation approaches model relationships among users, objects and tags using a tripartite graph, and hence overlook relationships within the same types of nodes. To overcome this limitation, we propose a novel approach, Trinity, to integrate historical data and tag information towards personalised recommendation. Trinity constructs a three-layered object-user-tag network that considers not only interconnections between different types of nodes but also relationships within the same types of nodes. Based on this heterogeneous network, Trinity adopts a random walk with restart model to assign the strength of associations to candidate objects, thereby providing a means of prioritizing the objects for a query user. We validate our approach via a series of large-scale 10-fold cross-validation experiments and evaluate its performance using three comprehensive criteria. Results show that our method outperforms several existing methods, including supervised random walk with restart, simulation of resource allocating processes, and traditional collaborative filtering.     

逃亡者的“天堂”

最近几个月来,我已经渐渐习惯了用手机阅读。没办法,地铁太拥挤,一本小小的书都不能展开,时间太紧张,一张报纸都来不及翻完,唯有手机小小的屏幕,动几下拇指,便能了解到最新鲜的信息,掌握最流行的资讯—就是在这种即时阅读带来的满足感冲击下,人们渐渐远离了传统阅读。     

Benefits of Facebook fan/brand page marketing and its influence on relationship commitment among Generation Y: Empirical evidence from Malaysia

This study aims to understand the influence of relational benefits of Facebook brand/fan page towards relationship commitment among Generation Y. Additionally, this study also investigates the mediating effect of customer satisfaction on the relationship between relational benefits and relationship commitment. A total of 195 sets of online questionnaire were collected using snowball sampling method for the statistical data requirement of SmartPLS. The analysis found significant positive relationships between relational benefits and relationship commitment, however, only on social, functional, and special treatment benefits. Surprisingly, the findings also showed an insignificant mediation effect of customer satisfaction on the relationship between relational benefits and relationship commitment. The research findings are valuable to both the theoretical and businesses adopting social media as a marketing strategy. Marketers employing the Facebook or other social media in catering and reacting to the Generation Y needs will benefit the most; securing their confidence and loyalty towards purchasing a certain brand.     

Digitized molecular diagnostics: reading disk-based bioassays with standard computer drives

We report herein a digital signal readout protocol for screening disk-based bioassays with standard optical drives of ordinary desktop/notebook computers. Three different types of biochemical recognition reactions (biotin-streptavidin binding, DNA hybridization, and protein-protein interaction) were performed directly on a compact disk in a line array format with the help of microfluidic channel plates. Being well-correlated with the optical darkness of the binding sites (after signal enhancement by gold nanoparticle-promoted autometallography), the reading error levels of prerecorded audio files can serve as a quantitative measure of biochemical interaction. This novel readout protocol is about 1 order of magnitude more sensitive than fluorescence labeling/scanning and has the capability of examining multiplex microassays on the same disk. Because no modification to either hardware or software is needed, it promises a platform technology for rapid, low-cost, and high-throughput point-of-care biomedical diagnostics.