Electrospinning, characterization and in vitro biological evaluation of nanocomposite fibers containing carbonated hydroxyapatite nanoparticles

Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) fibers containing carbonated hydroxyapatite (CHA) nanoparticles with different CHA amounts (5, 10 and 15 wt%) were electrospun with the aid of ultrasonic power for dispersing the nanoparticles. Scanning electron microscopy and energy-dispersive x-ray spectroscopy results showed that the distribution of CHA within the CHA/PHBV nanocomposite fibers was homogeneous when the CHA content was 10 wt%. Slight particle agglomeration occurred when the CHA content was 15 wt%. The diameters of the electrospun CHA/PHBV nanocomposite fibers and PHBV polymer fibers were around 3 μm. Fourier transform infrared spectroscopic analysis further confirmed the presence of CHA in CHA/PHBV nanocomposite fibers. Both PHBV and CHA/PHBV fibrous membranes exhibited similar tensile properties. Compared with PHBV solvent-cast film, the PHBV fibrous membrane was hydrophobic but the incorporation of CHA nanoparticles dramatically enhanced its wettability. In vitro studies revealed that both types of electrospun fibrous membranes (PHBV and CHA/PHBV) supported the proliferation of human osteoblastic cells (SaOS-2). The alkaline phosphatase activity of SaOS-2 cells seeded on the CHA/PHBV fibrous membranes was higher than that of the cells seeded on the PHBV fibrous membranes after 14 days of cell culture. The electrospun CHA/PHBV nanocomposite fibrous membranes show promises for bone tissue engineering applications. © 2010 IOP Publishing Ltd.postprin

Students and teacher’s attitudes and perceptions toward collaborative writing with WIKI in a Primary Four Chinese classroom

This case study investigated the attitudes and perceptions of primary school students and their teacher toward collaborative writing using a wiki technology in a Chinese writing class in China. An online collaborative writing environment named “Joyous Writing Club”(JWC) was designed and developed using a wiki. Participants included 59 primary four students and their Chinese language teacher. The study adopted a mixed-methods design, using quantitative and qualitative data. A writing attitude test was administered to the students using a pretest-posttest design, and JWC was used by the participants for a period of two months. After that, a questionnaire using responses on a 5-point Likert scale was administered to examine the students’ perceptions on the use of the wiki-based collaborative writing environment. A questionnaire consisting of open-ended queries was also administered to the teacher to gain her insights on using JWC with her students. The results indicated that students showed improvement in writing attitudes after engaging in collaborative writing with wiki. Students’ responses to the questionnaire revealed that they perceived the collaborative writing using a wiki as beneficial in facilitating motivation to write, heightened group interactions, and widening the reading audience of their writings. Students’ positive perceptions on the use of JWC were also found to associate positively with students’ writing attitudes in the posttest. The strongest positive correlation was found between perceptions on motivation to write and writing attitudes. The teacher reported that students expressed higher interest in writing on JWC compared relative to writing on paper. She also indicated that factors such as the topic of the Chinese composition and students’ computer skills may affect the quality of collaborative writing with wiki. This study provides information that may help teachers and researchers to understand students’ responses towards collaborative writing with a wiki environment in a Chinese writing class, and the factors that may facilitate the effective use of such wiki environment.postprin

Using a wiki-based collaborative process writing pedagogy to facilitate collaborative writing among Chinese primary school students

This case study explored collaborative writing in Chinese among 59 primary four Chinese students using a Wiki-based Collaborative Process Writing Pedagogy (WCPWP) in Shenzhen, China. It aimed mainly to design and orchestrate a WCPWP in order to facilitate students' Chinese writing. It investigated students' collaborative writing process and their performance on a wiki, and explored the perceptions and attitudes of the teacher and her students towards WCPWP. A wiki-based writing environment named Joyous Writing Club (JWC) was designed and developed using MediaWiki software. Data was collected from questionnaires, online wiki documents, interviews, and observations. The results illustrated students' collaborative writing process and their products on the wiki. Besides, the results showed that students perceived WCPWP was beneficial in boosting writing motivation, increasing group interactions, and extending the audience for their writing. This study may help primary educators gain a deeper understanding of the relationships between technology, pedagogy and education. It may also provide practical recommendations for primary school Chinese language teachers in the integration of Web 2.0 tools (wikis, Google Docs) as well as the use of effective pedagogical strategies in the teaching of Chinese writing.published_or_final_versio

Study on the selectivity of anion receptors by adjusting the distance of two urea fragments and their analytical application

Three anion receptors based on urea: 1 N, N'-bis-(p-nitrophenylaminocarbonyl)-Hydrazine, 2 N, N'-bis-(p-nitrophenylaminocar-bonyl)-ethylenediamine and 3 N, N'-bis-(p-nitrophenylaminocarbonyl)-1, 3-propane-diamine are designed and synthesized. Studies of UV-vis spectra presented that 1 was an excellent sensor of F- and 2 was sensitive to H2PO4 (-). Unfortunately, 3 can not distinguish the anions investigated in this paper. The color changes of the hosts upon the addition of a variety of structurally different anions were also utilized as naked-eye detection which is very convenient. It also revealed significantly that the distance between two recognition sites of receptor had an immediate effect on the selectivity of receptor for anions, which had been confirmed by the H-1 NMR titration and IR

Temporal-spatial analysis of severe acute respiratory syndrome among hospital inpatients

Background. We report the temporal-spatial spread of severe acute respiratory syndrome (SARS) among inpatients in a hospital ward during a major nosocomial outbreak and discuss possible mechanisms for the outbreak. Methods. All inpatients who had stayed in the same ward as the initial index case patient for any duration before isolation were recruited into a cohort and followed up to document the occurrence of SARS. The normalized concentration of virus-laden aerosols at different locations of the ward was estimated by use of computational fluid dynamics modeling. The attack rates in the various subgroups stratified by bed location were calculated. Multivariate Cox proportional hazards regression was used to document important risk factors. Results. The overall attack rate of SARS was 41% (30 of 74 subjects). It was 65%, 52%, and 18% in the same bay, adjacent bay, and distant bays, respectively (P = .001). Computation fluid dynamics modeling indicated that the normalized concentration of virus-laden aerosols was highest in the same bay and lowest in the distant bays. Cox regression indicated that staying in the ward on 6 or 10 March entailed higher risk, as well as staying in the same or adjacent bays. The epidemic curve showed 2 peaks, and stratified analyses by bed location suggested >1 generation of spread. Conclusions. The temporal-spatial spread of SARS in the ward was consistent with airborne transmission, as modeled by use of computational fluid dynamics. Infected health care workers likely acted as secondary sources in the latter phase of the outbreak. © 2005 by the Infectious Diseases Society of America. All rights reserved.published_or_final_versio

An acetate sensor based on azo in aqueous media

A colorimetric sensor 1,N,N'-di-(2-hydroxy-5-(phenldiazenyl)benzaldehyde)-1,3-diiminothiourea for acetate in DMSO and 9/1 DMSO/H(2)O (v/v) mixtures was designed and synthesized. The binding ability evaluated by UV-vis experiment reveals that sensor 1 can selectively recognize acetate. In addition, the color changes induced by anions can provide a way of detection by 'naked-eye'. The further insights to the nature of interactions between the sensor 1 and AcO(-) were investigated by (1)H NMR titration experiments in 9/1 DMSO-d(6)/H(2)O (v/v). (c) 2010 Elsevier B.V. All rights reserved

Studying ICT supported pedagogical practices

During the past decade there has been an exponential growth in the use of information and communication technology (ICT) and this has made pervasive impacts both on the society and on our daily lives. It is thus not surprising to find increasing interest, attention and investment put into the use of ICT in education all around the world. In addition to efforts to make use of ICT to improve learning, the emergence of the knowledge economy has also brought about in recent years a much greater emphasis on education and a number of masterplans in ICT in education has been produced in many countries. Such masterplans detailed not only strategies for implementation but more importantly embedded the plans within a broader framework of education reform that aimed to develop students’ capacities for self-learning, problem-solving, information seeking and analysis, critical thinking and the ability to communicate, collaborate and learn via the internet, abilities that figured much less importantly in the school curricula before. In this context, a new term, “emerging pedagogical practice”, was used in SITES (the Second International Information Technology in Education Study, conducted under the auspices of the IEA) (Pelgrum, 1999) to highlight the changing pedagogical goals and practices that has resulted from the use of ICT in education, as opposed to those uses that just aimed at enhancing the effectiveness of “traditionally important pedagogical practices”. However, the concept of “emerging pedagogical practice” as depicted in the SITES Module 1 (M1) report is still rather vague. When schools have access to computers and the Internet to support teaching and learning, how would teachers and students make use of them? What impact has ICT made on classroom practices? What changes, if any, has ICT made on the roles of teachers and students and the interactions between them? Has the introduction of ICT in schools brought about the desired education reforms envisaged in the ICT in education masterplans or are these wishful optimisms? Are there more effective models of ICT implementation in schools, and if so what are their characteristics? In conjunction with the SITES M1 Hong Kong study, we have conducted a study of good practices in the use of ICT for teaching and learning using the case studies approach. The main goal of this extension study was to explore the above questions in the context of good practices as commonly recognized by members of the education community, and to develop ways of disseminating such good practices. This paper describes the conceptual framework and methodology used in this study and reports briefly on some key findings from the study. The research methodology used in this Study is based on a model of pedagogical practice that is couched within a broad curriculum framework where the pedagogical practice is the implemented curriculum. There are two parts to the research. The first part is to investigate and to build models of pedagogical practices involving use of ICT. Here the assumption (substantiated by observations) is that the way ICT is incorporated into classrooms is very much dictated by the teachers’ general beliefs and approaches to education. The second component of the methodology deals with the models (strategies) of educational change used in different schools in introducing ICT across the curriculum and to explore if particular models of pedagogical practice is linked with specific school implementation strategies.published_or_final_versio

Effect of Ovariectomy on Stimulating Intracortical Remodeling in Rats

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Antibacterial effects of the essential oil from flower buds of Magnolia biondii Pamp

Flower buds of Magnolia biondii Pamp (family Magnoliaceae) is known as Xin-Yi in the Chinese Pharmacopoeia, and is widely used for the treatment of allergic rhinitis, rhinosinusitis, nasal congestion, and headache.1 Bacterial infection caused by Staphylococcus aureus in the-nasal-sinus mucosa is one of key factors which could cause rhinosinusitis,2 thus it is important to evaluate the antibacterial effect of the extracts from M. biondii, which may provide scientific evidence of using Xin-Yi for the treatment of rhinosinusitis. In this study, the essential oil and lignan-rich extract isolated from the flower buds of Magnolia biondii Pamp (Xin-Yi) were investigated for their chemical compositions and in vitro antibacterial activities. GC-MS analysis of the Magnolia essential oil disclosed the presence of 56 compounds including camphor (10.6%), eucalyptol (25.0%), linalool (5.8%), terpine-4-ol (8.4%), alpha-terpineol (19.8%), alpha-cadinol (3.3%), citronellol (2.9%), geraniol (2.3%), and trans-farnesol (8.7%). Both GC-MS and NMR analyses of the chloroform extract disclosed the presence of 7 tetrahydrofurofuran lignans that were demethoxyaschantin, fargesin, epieudesmin, eudesmin, aschantin, magnolin, and yangambin. The essential oil showed stronger antibacterial activities than the lignan-rich extract against five bacteria including pathogenic Staphylococcus aureus and S. epidermidis with MICs ranging from 250 to 500 µg ml-1 using microplate Alamar blue assay. Time-kill kinetics was used to monitor the survival characteristics of S. aureus and Escherichia coli in the presence of the essential oil over 24 hours, which indicated rapidly bactericidal effects. Scanning electron microscopy (Figure 1) showed the change of morphological appearance of S. aureus through destruction its cell wall and membrane by the Magnolia oil