A preliminary study on criteria weights for a library's digital resource selection:From the viewpoints of both users and librarians

Through investigating both users' and librarians' perceptions of the relative importance of the major criteria governing the selection of digital resources, we attempted to develop a criterion weight framework for a library's selection of digital resources, which can meet both the users' requirements and the library's goal of developing digital collections. The respective weight of each specific criterion is decided through the Analytic Hierarchy Process(AHP) Method. The findings of this study indicate that, when assigning weights to the selection criteria, it is important to consult the opinions of a wide crosssection of people, especially the views of different users. As a result, the digital resource selection system characterized by the criteria weights can reflect more comprehensively the users' requirements, and meanwhile it enables librarians' more rational selection of digital resources.

New insights into the formation of ammonium nitrate from a physical and chemical level perspective

High levels of fine particulate matter(PM_(2.5))is linked to poor air quality and premature deaths,so haze pollution deserves the attention of the world.As abundant inorganic components in PM_(2.5),ammonium nitrate(NH_(4)NO_(3))formation includes two processes,the diffusion process(molecule of ammonia and nitric acid move from gas phase to liquid phase)and the ionization process(subsequent dissociation to form ions).In this study,we discuss the impact of meteorological factors,emission sources,and gaseous precursors on NH4NO3 formation based on thermodynamic theory,and identify the dominant factors during clean periods and haze periods.Results show that aerosol liquid water content has a more significant effect on ammonium nitrate formation regardless of the severity of pollution.The dust source is dominant emission source in clean periods;while a combination of coal combustion and vehicle exhaust sources is more important in haze periods.And the control of ammonia emission is more effective in reducing the formation of ammonium nitrate.The findings of this work inform the design of effective strategies to control particulate matter pollution.

Nanocrystal technology for drug formulation and delivery

With the development of modem technology like high throughput screening, combinatorial chemistry and computer aid drug design, the drug discovery process has been dramatically accelerated. However, new drug candidates often exhibit poor aqueous or even organic medium solubility. Additionally, many of them may have low dissolution velocity and low oral bioavailability. Nanocrystal formulation sheds new light on advanced drug development. Due to small （nano- or micro- meters） sizes, the increased surface-volume ratio leads to drama- tically enhanced drug dissolution velocity and saturation solubility. The simplicity in preparation and the potential for various administration routes allow drug nanocrystals to be a novel drug delivery system for specific diseases （i.e. cancer）. In addition to the comprehensive review of different technologies and methods in drug nanocrystal preparation, suspension, and stabilization, we will also compare nano- and micro-sized drug crystals in pharma- ceutical applications and discuss current nanocrystal drugs on the market and their limitations.