Characterization of Calcium Alginate Beads Containing Structurally Similar Drugs

ABSTRACT

The aim of this study was to investigate the characteristics of alginate beads prepared by ionotropic gelation in which structurally similar drugs were incorporated. For this purpose theophylline and theobromine were selected as model drugs. The influence of incorporated drugs on bead characteristics such as size, shape, and morphology, as well as encapsulation efficiency, was examined. It was found that theobromine as well as theophylline content in beads significantly decreased with increasing hardening time due to drug diffusion into the hardening media. In theobromine beads the drug content was extremely improved by dropping the alginate and drug solution into an acidic calcium chloride solution, while theophylline content was to some extent improved by the hardening of beads in a calcium chloride solution saturated with the drug. The most evident difference between theophylline and theobromine beads was in their shape and morphology. Theobromine beads were round, while theophylline ones had an irregular shape with an extremely wrinkled surface. The distinction in shape was highly dependent on drug content. Additionally, it was demonstrated that beads' shape was dependent on preparation conditions as well. On the basis of x-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) analyses and scanning electron microscope (SEM) photographs it was found that the most of the drug in bead was present in an amorphous state. Therefore, it is suggested that some drug–alginate interactions could be present in beads and might be responsible for the different shape of theophylline and theobromine beads.

Thus it can be concluded that the preparation of beads by ionotropic gelation cannot be generalized even though structurally similar drugs are incorporated.     

Improved Optimization Formulations for Launching Nose of Incrementally Launched Prestressed Concrete Bridges

The conventional design process of a launching nose of an incrementally launched bridge is based on trial-and-error methods to reduce bending moment of prestressed concrete deck at the foremost support during launch. With this method, there is no guarantee that the obtained solution is the best among all the possible solutions, since they all depend on the experience and intuition of a designer, and they are also restricted by a limited number of possible iterations. Given that launched bridges constitute an important constructive typology, all the available capacities of design innovation should be incorporated, including numerical optimization. This research work proposes an objective and rigorous formulation to optimize the launching nose of a launched bridge under real constraints that a bridge designer can encounter in practice. Comparing the results obtained by conventional process and those obtained by optimization techniques allows us to verify that some of the assumptions considered in classical design methods of a launching nose are not based on any theoretical foundation. This fact demonstrates the utility of numerical optimization to improve a design.     

Corona noise on a 400 kV overhead power line: Measurements and computer modeling

The paper presents experimental research into the corona noise performed on a 400 kV overhead power line with a horizontal disposition of conductors. The high-voltage power line in its role of a communication channel is a source of different noises, characterizing an important feature of this communication media. The main objective was measuring and modeling the corona noise. Measurements of the power spectrum density and relative corona noise within a power frequency period are presented for different weather conditions. The algorithm for measuring variations in the corona noise level is described on the basis of noise samples. The maximum peaks exceed the root-mean square noise level by 7.95 dB in foul weather conditions and by 2.9 dB in fair weather conditions. An appropriate computer model of the corona noise compliant with the measurement results is proposed.     

User-centred app design for speech sound disorders interventions with tablet computers

Traditional speech and language pathology practice (SLPP) faces challenges delivering effective and timely therapy due to long waiting lists, the need for regular practice outside the clinic and a lack of children’s motivation to engage in persistent practice. Technology has untapped potential to address these issues and improve SLPP. This paper describes the design of a tablet app for delivering technology-enhanced therapy for children with speech sound disorders and investigates the impact of the use of apps on SLPP. The initial design was informed by a nation-wide survey of speech-language pathologists (SLPs). The quantitative analysis disclosed that even though SLPs positively perceive mobile technology, they do not currently fully exploit it in their practice due to a lack of apps in their native language and the limited usefulness of apps in foreign languages. Using a user-centred design process, a multidisciplinary team created three prototypes and a final version of an app that has been tested in real therapeutic sessions during everyday practice and informed by feedback from SLPs and children. The observation analysis is presented based on an adaptation of Koole’s FRAME model. The qualitative findings indicate that SLPs identify mobile apps as enabling greater mobility, allowing new therapeutic approaches, creating possibilities for practice outside the therapeutic setting and increasing children’s motivation, supporting greater persistence to practise in the context of the therapy.     

Test generation for technology-specific multi-faults based on detectable perturbations

In this paper, we introduce the concept of detectable perturbations as a method to generate tests that cover any technology-specific faults such as multiple bridging, open and stuck-at faults. Rather than devising a customized test pattern generation system for each class of technology-specific faults, we implemented a generic system to generate tests for single and multiple perturbations. We demonstrate the versatility of this approach by generating tests for a set of large benchmark circuits that have been mapped into single- and multi-output modules. These tests cover single stuck-at, multi-output bridging, stuck-at, as well as any mutation faults in the functionality of the technology-mapped cells. Experimental results provide useful insights about the quality of single stuck-at test patterns versus coverages for the additional classes of faults.     

Kinetics and mechanism of reaction in the zeolitic tuff-CaO---H2O systems at increased temperature

Kinetics and mechanism of reactions in the zeolitic tuff-CaO---H₂O systems have been studied at increased temperature (65°C) by means of X-ray diffraction and SEM. These reactions yield macrokinetic image of consecutive diffusion-controlled topochemical reactions. The initial process consists of the diffusive dissolution of zeolite and portlandite. The final product (tobermorite) is formed by heterogeneus nucleation on the solid (CSH I) - liquid (solution) interface.     

FUNCTIONALITY FAULT MODEL: A BASIS FOR TECHNOLOGY-SPECIFIC TEST GENERATION

In this paper, we present the functionality fault model and demonstrate its feasibility and advantages. In current designs, the fan-in of the modules implemented in CMOS standard cell, mask programmable or field-programmable gate array technologies rarely exceeds 4 on average. A functionality fault model, based on the complete enumeration of the truth table of each logic module, is thus entirely feasible and enhances the quality of the test significantly. Tests based on this model provide complete coverage of module behavior and interior faults as well as input stuck-at and bridging faults of any multiplicity, reducing the need for technology and implementation-specific fault models. We have implemented the prototype software test-dc and demonstrated its application to generate high-quality test patterns.     

Computation of high-frequency and time characteristics of corona noise on HV power line

This work presents an algorithm for the computation of frequency and time characteristics of the corona noise in power-line carrier communications. In the frequency domain, the corona noise is represented with a power spectral density and with a Gaussian noise voltage with variable root mean square value in the time domain. Simulations results are compared with measurements on an actual 400-kV power line.