Towards a better understanding of the release mechanisms of caffeine from PLGA microparticles

Poly(lactic-co-glycolic acid) (PLGA)-based microparticles can be successfully used to control the release rate of a drug and optimize the therapeutic efficacy of a medical treatment. However, the underlying drug release mechanisms can be complex and are often not fully understood. This renders system optimization cumbersome. In this study, differently sized caffeine-loaded PLGA microparticles were prepared and the swelling and drug release behaviors of single microparticles were monitored upon exposure to phosphate buffer pH 7.4. Ensembles of microparticles were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, gel permeation chromatography, and optical microscopy. The observed triphasic drug release patterns could be explained as follows. The initial burst release can be attributed to the dissolution of tiny drug crystals with direct surface access. The subsequent second drug release phase (with an about constant release rate) could be attributed to the release of drug crystals in regions, which undergo local swelling. The third release phase (again rapid, leading to complete drug exhaust) could be explained by substantial polymer swelling throughout the systems. Once a critical polymer molecular weight is reached, the PLGA chains are sufficiently hydrophilic, insufficiently entangled and the osmotic pressure created by water soluble degradation products attracts high amounts of water into the system. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48710.     

Integrating dynamic spectrum access and device‐to‐device via cloud radio access networks and cognitive radio

Dynamic Spectrum Access (DSA) can be integrated with Device‐to‐Device (D2D) communications to enable the exploitation of unused spectrum portions and to address the spectrum scarcity problem. Spectrum management mechanisms integrated into DSA and D2D allow low‐power communications between User Equipments without interfering with licensed primary users. However, these mechanisms tend to be energy and processing intensive, being unfeasible to implement in User Equipments with strict battery and processing limitations. On the other hand, Cloud Radio Access Networks already leverage the virtually unlimited computing capacity of clouds for baseband processing functions. Thus, in this article, we propose the Cognitive Radio Device‐to‐Device (CRD2D) approach aiming to offload spectrum management functionality to the cloud taking advantage of Cloud Radio Access Networks architecture to support the integration of DSA and D2D.     

Effects of accessible website design on nondisabled users: age and device as moderating factors

This study examined how implementing recommendations from Web accessibility guidelines affects nondisabled people in different age groups using different technical devices. While recent research showed positive effects of implementing such recommendations for nondisabled users, it remains unclear whether such effects would apply to different age groups and kind of devices. A 2 × 2 × 2 design was employed with website accessibility (high accessibility vs. very low accessibility), age (younger adults vs. older adults) and type of device (laptop vs. tablet) as independent variables. 110 nondisabled participants took part in a usability test, in which performance and satisfaction were measured as dependent variables. The results showed that higher accessibility increased task completion rate, task completion time and satisfaction ratings of nondisabled users. While user age did not have any effects, users showed faster task completion time under high accessibility when using a tablet rather than a laptop. The findings confirmed previous findings, which showed benefits of accessible websites for nondisabled users. These beneficial effects may now be generalised to a wide age range and across different devices.

Practitioner Summary: This work is relevant to the design of websites since it emphasises the need to consider the characteristics of different user groups. Accessible website design (aimed at users with disabilities) leads to benefits for nondisabled users across different ages. These findings provide further encouragement for practitioners to apply WCAG 2.0.     

Controller synthesis for dynamic hierarchical real-time plants using timed automata

We use timed I/O automata based timed games to synthesize task-level reconfiguration services for cost-effective fault tolerance in a case study. The case study shows that state-space explosion is a severe problem for timed games. By applying suitable abstractions, we dramatically improve the scalability. However, timed I/O automata do not facilitate algorithmic abstraction generation techniques. The case study motivates the development of timed process automata to improve modeling and analysis for controller synthesis of time-critical plants which can be hierarchical and dynamic. The model offers two essential features for industrial systems: (i) compositional modeling with reusable designs for different contexts, and (ii) state-space reduction technique. Timed process automata model dynamic networks of continuous-time communicating plant processes which can activate other plant processes. We show how to establish safety and reachability properties of timed process automata by reduction to solving timed games. To mitigate the state-space explosion problem, an algorithmic state-space reduction technique using compositional reasoning and aggressive abstractions is also proposed. In this article, we demonstrate the theoretical framework of timed process automata and the effectiveness of the proposed state-space reduction technique by extending the case study.     

Model development guidelines for UML-RT: conventions,patterns and antipatterns

Software development guidelines are a set of rules which can help improve the quality of software. These rules are defined on the basis of experience gained by the software development community over time. This paper discusses a set of design guidelines for model-based development of complex real-time embedded software systems. To be precise, we propose nine design conventions, three design patterns and thirteen antipatterns for developing UML-RT models. These guidelines have been identified based on our analysis of around 100 UML-RT models from industry and academia. Most of the guidelines are explained with the help of examples, and standard templates from the current state of the art are used for documenting the design rules.     

IBMSan Francisco

This article presents the architecture of the IBM San Francisco frameworks and provides additional information on the San Francisco layers and extension mechanisms. San Francisco leverages the power of Java and distributed object computing to provide a solid foundation for robust, Internet-enabled, cross-platform, scalable software solutions for specific industry domains. San Francisco components are designed as frameworks that provide an object-oriented infrastructure, a consistent application programming model and default business logic.     

Ability of naturally occurring parasitoids to suppress the introduced pest Prostephanus truncatus (Horn) (Coleoptera, Bostrichidae) in traditional maize stores in Togo

Beneficial parasitoids associated with traditional maize stores in southern Togo were collected during three storage seasons (1988–1990) at different sites to investigate their relationship to the introduced pest, Prostephanus truncatus. Two parasitoids, Anisopteromalus calandrae and Theocolax elegans were observed regularly and in higher numbers in the samples and were therefore studied for their relationship with P. truncatus. Correlation analysis of population densities observed in stores showed that correlation coefficients for numbers of both parasitoids and P. truncatus were mainly negative and very close to zero, but positive and greater in value for the parasitoids and Sitophilus zeamais. Glass jar trials were carried out with A. calandrae and T. elegans on loose maize. A. calandrae reduced numbers of P. truncatus by 70.1% in the single species culture after 8 weeks, whereas T. elegans had no impact. In double species culture A. calandrae had an effect on both populations; P. truncatus was reduced by 61.3% and S. zeamais by 22.5%. T. elegans only had an influence on S. zeamais.     

Semicontinuous granulation—the process of choice for the production of pharmaceutical granules?

Tablets represent the majority of dosage forms sold worldwide. High-quality granules are a prerequisite for a robust manufacturing of millions and millions of tablets needed. Thus, the preparation of pharmaceutical granules is an important standard operation procedure in the pharmaceutical industry. Due to the pressure on the costs of medication, there is a constant search for new concepts to reduce the manufacturing costs and the time to market keeping simultaneously constant or even improving the quality of the product. With respect to this trend, the following questions and problems will be treated in detail. (1) Is it possible to replace in the pharmaceutical industry the batch-type manufacturing process for granules by a quasi-continuous or continuous process being successfully introduced in the food industry? (2) Can scale-up problems be avoided by introducing a quasi-continuous process? (3) Using a continuous process, is it possible to keep or even to improve the high quality of the granules? (4) Is it possible to increase the productivity? (5) What will be the cost savings using a quasi-continuous process compared to the classical batch-type procedure? (6) Is it possible to shorten the development time, i.e. the time to market for a new product using a continuous or quasi-continuous manufacturing process for pharmaceutical granules? (7) What type of organizational business model is needed to achieve the desired results? Experiences with a new quasi-continuous equipment, the Glatt Multicell^R, will be presented as a case study.