Preparation of macroporous methacrylate monolithic material with convective flow properties for bioseparation : Investigating the kinetics of pore formation and hydrodynamic performance

The preparation of macroporous methacrylate monolithic material with controlled pore structures can be carried out in an unstirred mould through careful and precise control of the polymerisation kinetics and parameters. Contemporary synthesis conditions of methacrylate monolithic polymers are based on existing polymerisation schemes without an in-depth understanding of the dynamics of pore structure and formation. This leads to poor performance in polymer usage thereby affecting final product recovery and purity, retention time, productivity and process economics. The unique porosity of methacrylate monolithic polymer which propels its usage in many industrial applications can be controlled easily during its preparation. Control of the kinetics of the overall process through changes in reaction time, temperature and overall composition such as cross-linker and initiator contents allow the fine tuning of the macroporous structure and provide an understanding of the mechanism of pore formation within the unstirred mould. The significant effect of temperature of the reaction kinetics serves as an effectual means to control and optimise the pore structure and allows the preparation of polymers with different pore size distributions from the same composition of the polymerisation mixture. Increasing the concentration of the cross-linking monomer affects the composition of the final monoliths and also decreases the average pore size as a result of pre-mature formation of highly cross-linked globules with a reduced propensity to coalesce. The choice and concentration of porogen solvent is also imperative. Different porogens and porogen mixtures present different pore structure output. Example, larger pores are obtained in a poor solvent due to early phase separation.

Mesoporous silica spheres from colloids

A novel method has been developed to synthesize mesoporous silica spheres using commercial silica colloids (SNOWTEX) as precursors and electrolytes (ammonium nitrate and sodium chloride) as destabilizers. Crosslinked polyacrylamide hydrogel was used as a temporary barrier to obtain dispersible spherical mesoporous silica particles. The influences of synthesis conditions including solution composition and calcination temperature on the formation of the mesoporous silica particles were systematically investigated. The structure and morphology of the mesoporous silica particles were characterized via scanning electron microscopy (SEM) and N2 sorption technique. Mesoporous silica particles with particle diameters ranging from 0.5 to 1.6 μm were produced whilst the BET surface area was in the range of 31-123 m2 g-1. Their pore size could be adjusted from 14.1 to 28.8 nm by increasing the starting particle diameter from 20-30 nm up to 70-100 nm. A simple and cost effective method is reported that should open up new opportunities for the synthesis of scalable host materials with controllable structures.

Photochemical design of stimuli-responsive nanoparticles prepared by supramolecular host–guest chemistry

We introduce the design of a thermoresponsive nanoparticle via sacrificial micelle formation based on supramolecular host–guest chemistry. Reversible addition–fragmentation chain transfer (RAFT) polymerization was employed to synthesize well-defined polymer blocks of poly(N,N-dimethylacrylamide) (poly(DMAAm)) (Mn,SEC = 10 700 g mol–1, Đ = 1.3) and poly(N-isopropylacrylamide) (poly(NiPAAm)) (Mn,SEC = 39 700 g mol–1, Đ = 1.2), carrying supramolecular recognition units at the chain termini. Further, 2-methoxy-6-methylbenzaldehyde moieties (photoenols, PE) were statistically incorporated into the backbone of the poly(NiPAAm) block as photoactive cross-linking units. Host–guest interactions of adamantane (Ada) (at the terminus of the poly(NiPAAm/PE) chain) and β-cyclodextrin (CD) (attached to the poly(DMAAm chain end) result in a supramolecular diblock copolymer. In aqueous solution, the diblock copolymer undergoes micellization when heated above the lower critical solution temperature (LCST) of the thermoresponsive poly(NiPAAm/PE) chain, forming the core of the micelle. Via the addition of a 4-arm maleimide cross-linker and irradiation with UV light, the micelle is cross-linked in its core via the photoinduced Diels–Alder reaction of maleimide and PE units. The adamantyl–cyclodextrin linkage is subsequently cleaved by the destruction of the β-CD, affording narrowly distributed thermoresponsive nanoparticles with a trigger temperature close to 30 °C. Polymer chain analysis was performed via size exclusion chromatography (SEC), nuclear magnetic resonance (NMR) spectroscopy, and dynamic light scattering (DLS). The size and thermoresponsive behavior of the micelles and nanoparticles were investigated via DLS as well as atomic force microscopy (AFM).

Feasibility of autologous bone marrow mesenchymal stem cell-derived extracellular matrix scaffold for cartilage tissue engineering

Extracellular matrix (ECM) materials are widely used in cartilage tissue engineering. However, the current ECM materials are unsatisfactory for clinical practice as most of them are derived from allogenous or xenogenous tissue. This study was designed to develop a novel autologous ECM scaffold for cartilage tissue engineering. The autologous bone marrow mesenchymal stem cell-derived ECM (aBMSC-dECM) membrane was collected and fabricated into a three-dimensional porous scaffold via cross-linking and freeze-drying techniques. Articular chondrocytes were seeded into the aBMSC-dECM scaffold and atelocollagen scaffold, respectively. An in vitro culture and an in vivo implantation in nude mice model were performed to evaluate the influence on engineered cartilage. The current results showed that the aBMSC-dECM scaffold had a good microstructure and biocompatibility. After 4 weeks in vitro culture, the engineered cartilage in the aBMSC-dECM scaffold group formed thicker cartilage tissue with more homogeneous structure and higher expressions of cartilaginous gene and protein compared with the atelocollagen scaffold group. Furthermore, the engineered cartilage based on the aBMSC-dECM scaffold showed better cartilage formation in terms of volume and homogeneity, cartilage matrix content, and compressive modulus after 3 weeks in vivo implantation. These results indicated that the aBMSC-dECM scaffold could be a successful novel candidate scaffold for cartilage tissue engineering.

Wetting, solubility and chemical characteristics of plasma-polymerized 1-isopropyl-4-methyl-1,4-cyclohexadiene thin films

Investigations on the wetting, solubility and chemical composition of plasma polymer thin films provide an insight into the feasibility of implementing these polymeric materials in organic electronics, particularly where wet solution processing is involved. In this study, thin films were prepared from 1-isopropyl-4-methyl-1,4-cyclohexadiene (γ-Terpinene) using radio frequency (RF) plasma polymerization. FTIR showed the polymers to be structurally dissimilar to the original monomer and highly cross-linked, where the loss of original functional groups and the degree of cross-linking increased with deposition power. The polymer surfaces were hydrocarbon-rich, with oxygen present in the form of O–H and C=O functional groups. The oxygen content decreased with deposition power, with films becoming more hydrophobic and, thus, less wettable. The advancing and receding contact angles were investigated, and the water advancing contact angle was found to increase from 63.14° to 73.53° for thin films prepared with an RF power of 10 W to 75 W. The wetting envelopes for the surfaces were constructed to enable the prediction of the surfaces’ wettability for other solvents. The effect of roughness on the wetting behaviour of the films was insignificant. The polymers were determined to resist solubilization in solvents commonly used in the deposition of organic semiconducting layers, including chloroform and chlorobenzene, with higher stability observed in films fabricated at higher RF power.

Solubility and surface interactions of RF plasma polymerized polyterpenol thin films

Organic thin films have myriad of applications in biological interfaces, micro-electromechanical systems and organic electronics. Polyterpenol thin films fabricated via RF plasma polymerization have been substantiated as a promising gate insulating and encapsulating layer for organic optoelectronics, sacrificial place-holders for air gap fabrication as well as antibacterial coatings for medical implants. This study aims to understand the wettability and solubility behavior of the nonsynthetic polymer thin film, polyterpenol. Polyterpenol exhibited monopolar behavior, manifesting mostly electron donor properties, and was not water soluble due to the extensive intermolecular and intramolecular hydrogen bonds present. Hydrophobicity of polyterpenol surfaces increased for films fabricated at higher RF power attributed to reduction in oxygen containing functional groups and increased cross linking. The studies carried out under various deposition conditions vindicate that we could tailor the properties of the polyterpenol thin film for a given application.

Cross-Lingual knowledge discovery : Chinese-to-English article linking in Wikipedia

In this paper we examine automated Chinese to English link discovery in Wikipedia and the effects of Chinese segmentation and Chinese to English translation on the hyperlink recommendation. Our experimental results show that the implemented link discovery framework can effectively recommend Chinese-to-English cross-lingual links. The techniques described here can assist bi-lingual users where a particular topic is not covered in Chinese, is not equally covered in both languages, or is biased in one language; as well as for language learning.

A Virtual Evaluation Track for Cross Language Link Discovery

The Wikipedia has become the most popular online source of encyclopedic information. The English Wikipedia collection, as well as some other languages collections, is extensively linked. However, as a multilingual collection the Wikipedia is only very weakly linked. There are few cross-language links or cross-dialect links (see, for example, Chinese dialects). In order to link the multilingual-Wikipedia as a single collection, automated cross language link discovery systems are needed – systems that identify anchor-texts in one language and targets in another. The evaluation of Link Discovery approaches within the English version of the Wikipedia has been examined in the INEX Link the-Wiki track since 2007, whilst both CLEF and NTCIR emphasized the investigation and the evaluation of cross-language information retrieval. In this position paper we propose a new virtual evaluation track: Cross Language Link Discovery (CLLD). The track will initially examine cross language linking of Wikipedia articles. This virtual track will not be tied to any one forum; instead we hope it can be connected to each of (at least): CLEF, NTCIR, and INEX as it will cover ground currently studied by each. The aim is to establish a virtual evaluation environment supporting continuous assessment and evaluation, and a forum for the exchange of research ideas. It will be free from the difficulties of scheduling and synchronizing groups of collaborating researchers and alleviate the necessity to travel across the globe in order to share knowledge. We aim to electronically publish peer-reviewed publications arising from CLLD in a similar fashion: online, with open access, and without fixed submission deadlines.

Overview of the NTCIR-9 crosslink task : cross-lingual link discovery

This paper presents an overview of NTCIR-9 Cross-lingual Link Discovery (Crosslink) task. The overview includes: the motivation of cross-lingual link discovery; the Crosslink task definition; the run submission specification; the assessment and evaluation framework; the evaluation metrics; and the evaluation results of submitted runs. Cross-lingual link discovery (CLLD) is a way of automatically finding potential links between documents in different languages. The goal of this task is to create a reusable resource for evaluating automated CLLD approaches. The results of this research can be used in building and refining systems for automated link discovery. The task is focused on linking between English source documents and Chinese, Korean, and Japanese target documents.

The uses of multilingualism in digital culture : the case of inter-language linking

Language-use has proven to be the most complex and complicating of all Internet features, yet people and institutions invest enormously in language and crosslanguage features because they are fundamental to the success of the Internet’s past, present and future. The thesis takes into focus the developments of the latter – features that facilitate and signify linking between or across languages – both in their historical and current contexts. In the theoretical analysis, the conceptual platform of inter-language linking is developed to both accommodate efforts towards a new social complexity model for the co-evolution of languages and language content, as well as to create an open analytical space for language and cross-language related features of the Internet and beyond. The practiced uses of inter-language linking have changed over the last decades. Before and during the first years of the WWW, mechanisms of inter-language linking were at best important elements used to create new institutional or content arrangements, but on a large scale they were just insignificant. This has changed with the emergence of the WWW and its development into a web in which content in different languages co-evolve. The thesis traces the inter-language linking mechanisms that facilitated these dynamic changes by analysing what these linking mechanisms are, how their historical as well as current contexts can be understood and what kinds of cultural-economic innovation they enable and impede. The study discusses this alongside four empirical cases of bilingual or multilingual media use, ranging from television and web services for languages of smaller populations, to large-scale, multiple languages involving web ventures by the British Broadcasting Corporation, the Special Broadcasting Service Australia, Wikipedia and Google. To sum up, the thesis introduces the concepts of ‘inter-language linking’ and the ‘lateral web’ to model the social complexity and co-evolution of languages online. The resulting model reconsiders existing social complexity models in that it is the first that can explain the emergence of large-scale, networked co-evolution of languages and language content facilitated by the Internet and the WWW. Finally, the thesis argues that the Internet enables an open space for language and crosslanguage related features and investigates how far this process is facilitated by (1) amateurs and (2) human-algorithmic interaction cultures.

Speaker linking using complete-linkage clustering

Speaker diarization determines instances of the same speaker within a recording. Extending this task to a collection of recordings for linking together segments spoken by a unique speaker requires speaker linking. In this paper we propose a speaker linking system using linkage clustering and state-of-the-art speaker recognition techniques. We evaluate our approach against two baseline linking systems using agglomerative cluster merging (AC) and agglomerative clustering with model retraining (ACR). We demonstrate that our linking method, using complete-linkage clustering, provides a relative improvement of 20% and 29% in attribution error rate (AER), over the AC and ACR systems, respectively.

Robust automatic speaker linking and attribution

This research makes a major contribution which enables efficient searching and indexing of large archives of spoken audio based on speaker identity. It introduces a novel technique dubbed as “speaker attribution” which is the task of automatically determining ‘who spoke when?’ in recordings and then automatically linking the unique speaker identities within each recording across multiple recordings. The outcome of the research will also have significant impact in improving the performance of automatic speech recognition systems through the extracted speaker identities.

Prescribing for nausea in palliative care : A cross-sectional national survey of Australian palliative medicine doctors

Background: Nausea can be a debilitating symptom for patients with a life-limiting illness. While addressing reversible components, nonpharmacological strategies and antiemetics are the main therapeutic option. The choice of medication, dose, and route of administration remain highly variable. Objective: The aim of this study was to codify the current clinical approaches and quantify any variation found nationally. Methods: A cross-sectional study utilizing a survey of palliative medicine clinicians examined prescribing preferences for nausea using a clinical vignette. Respondent characteristics, the use of nonpharmacological interventions, first- and second-line antiemetic choices, commencing and maximal dose, and time to review were collected. Results: Responding clinicians were predominantly working in palliative medicine across a range of settings with a 49% response rate (105/213). The main nonpharmacological recommendation was “small, frequent snacks.” Metoclopramide was the predominant first-line agent (69%), followed by haloperidol (26%), while second-line haloperidol was the predominant agent (47%), with wide variation in other nominated agents. Respondents favoring metoclopramide as first-line tended to use haloperidol second-line (65%), but not vice versa. Maximal doses for an individual antiemetic varied up to tenfold. Conclusion: For nausea, a commonly encountered symptom in palliative care, clinicians' favored metoclopramide and haloperidol; however, after these choices, there was large variation in antiemetic selection. While most clinicians recommended modifying meal size and frequency, use of other nonpharmacological therapies was limited.