Etude par diffraction des rayons X et par spectroscopies d'absorption infra-rouge et de diffusion raman des tantalates de strontium et de baryum de structure de type “blocs 1×2”

The structural characteristics from X ray diffraction powder patterns and indexed according to the Pnma space group are given for SrTa₂O₆ isomorphous with SrNb₂O₆ and for a modification of BaTa₂O₆ isomorphous with CaTa₂O₆. Cell parameters are refined for each compound. The force field of different niobates and tantalates of “1×2 block” type structure calculated from a vibrational analysis is then compared and the relative stability of the two modifications of BaTa₂O₆ is shown.     

Reversible Conductive Inkjet Printing of Healable and Recyclable Electrodes on Cardboard and Paper

Conductive inkjet printing with metal nanoparticles is irreversible because the particles are sintered into a continuous metal film. The resulting structures are difficult to remove or repair and prone to cracking. Here, a hybrid ink is used to obviate the sintering step and print interconnected particle networks that become highly conductive immediately after drying. It is shown that reversible conductive printing is possible on low‐cost cardboard samples after applying standard paper industry coats that are adapted in terms of surface energy and porosity. The conductivity of the printed films approaches that of sintered standard inks on the same substrate, but the mobility of the hybrid particle film makes them less sensitive to cracks during bending and folding of the substrate. Damages that occur can be partially repaired by wetting the film such that particle mobility is increased and particles move to bridge insulating gaps in the film. It is demonstrated that the conductive material can be recovered from the cardboard at the end of its life time and be redispersed to recycle the particles and reuse them in conductive inks.     

Solubility of core materials in aqueous polymeric solution effect on microencapsulation of curcumin

Curcumin, the main active constituent of turmeric herb (Curcuma longa L.) have been reported to possess many medicinal values. The application of curcumin in dermatological preparations is limited by their intense yellow color property, which stains the fabric and skin. The objectives of this study were to reduce the color staining effect and enhance the stability of curcumin via microencapsulation using gelatin simple coacervation method. As for curcumin, ethanol and acetone were used as coacervating solvents. Curcumin was dispersed in ethanol while dissolved in acetone. Irrespective of the types of coacervating solvents used, microencapsulation resolved the color-staining problem and enhanced the flow properties and photo-stability of curcumin. Nevertheless, it was found that more spherical curcumin microcapsules with higher yield, higher curcumin loading, and higher entrapment efficiency were obtained with acetone than ethanol. The in vitro release of curcumin after microencapsulation was slightly prolonged. Further evaluation of the effects of solubility of core materials in coacervating solvent or polymeric aqueous solution using six different drug compounds, namely, ketoconazole, ketoprofen, magnesium stearate, pseudoephedrine HCl, diclofenac sodium, and paracetamol, suggested that the solubility of core materials in aqueous polymeric solution determined the successful formation of microcapsules. Microcapsules could only be formed if the core materials were not dissolved in the aqueous polymeric solution while the core materials could either be dissolved or dispersed in the coacervating solvent. In summary, microencapsulation not only circumvents the color-staining problem but also improved the stability and flowability of curcumin. The solubility of core material in aqueous polymeric solution plays a pivotal role in determining the successful formation of microcapsules.     

Accumulation of silver nanoparticles by cultured primary brain astrocytes

Silver nanoparticles (AgNP) are components of various food industry products and are frequently used for medical equipment and materials. Although such particles enter the vertebrate brain, little is known on their biocompatibility for brain cells. To study the consequences of an AgNP exposure of brain cells we have treated astrocyte-rich primary cultures with polyvinylpyrrolidone (PVP)-coated AgNP. The incubation of cultured astrocytes with micromolar concentrations of AgNP for up to 24 h resulted in a time- and concentration-dependent accumulation of silver, but did not compromise the cell viability nor lower the cellular glutathione content. In contrast, the incubation of astrocytes for 4 h with identical amounts of silver as AgNO(3) already severely compromised the cell viability and completely deprived the cells of glutathione. The accumulation of AgNP by astrocytes was proportional to the concentration of AgNP applied and significantly lowered by about 30% in the presence of the endocytosis inhibitors chloroquine or amiloride. Incubation at 4?°C reduced the accumulation of AgNP by 80% compared to the values obtained for cells that had been exposed to AgNP at 37?°C. These data demonstrate that viable cultured brain astrocytes efficiently accumulate PVP-coated AgNP in a temperature-dependent process that most likely involves endocytotic pathways.     

Preparation and Characterization of Molecularly Imprinted Polymeric Nanoparticles for Atrial Natriuretic Peptide (ANP)

Natriuretic peptide receptor A (NPRA), the receptor for the cardiac hormone atrial natriuretic peptide (ANP), is expressed abundantly on cancer cells and disruption of ANP‐NPRA signaling inhibits tumor burden and metastasis. Since antagonists of NPRA signaling have not provided reproducible results, we reason that a synthetic neutralizing antibody to ANP, which has high selectivity and affinity for ANP, can be used to regulate ANP levels and attenuate NPRA signaling. In this study, we prepare molecularly imprinted polymeric nanoparticles (MIPNPs) for ANP using a short peptide of ANP as the template and determine their binding affinity and selectivity. The MIPNPs are prepared by precipitation polymerization using NH₂–SLRRSS–CONH₂, which is a short peptide from ANP, as a template, methacrylic acid and N‐isopropylacrylamide as functional monomers, and bis‐acrylamide as a crosslinker. The average diameters of the MIPNPs and of non‐imprinted nanoparticles (NIPNPs) in water are 215.8 ± 4.6 nm and 197.7 ± 3.1 nm respectively. The binding‐isotherm analysis shows that the MIPNPs have a much‐higher binding affinity for the template peptide and ANP than the NIPNPs. Scatchard analysis gives an equilibrium dissociation constant, K_d, of 7.3 × 10^?6 M with a binding capacity of 106.7 μmol g^?1 for the template peptide and a K_d of 7.9 × 10^?6 M with a binding capacity of 36.0 μmol g^?1 for the ANP. Measurements of the binding kinetics reveal that MIPNPs reach protein‐adsorption equilibrium in 30 min. The MIPNPs are found to have a high specificity for ANP with little affinity for BSA or scrambled ANP peptide. The MIPNPs also recognize and adsorb ANP in cell‐culture medium spiked with ANP and in human plasma. Taken together, these results indicate that the MIPNPs have a high affinity and selectivity for ANP and can be used as a synthetic antibody for modulating ANP‐NPRA signaling in cancers.     

Three-ways crossover bioequivalence study of cephalexin in healthy Malay volunteers

Context: Although the general pharmacokinetics of cephalexin is quite established up-to-date, however, no population-based study on Cephalexin pharmacokinetics profile in Malay population has been reported yet in the literature.

Objective: The objective of this study was to investigate the pharmacokinetics and to compare the bioavailability of three cephalexin products, Ospexin® versus MPI Cephalexin® tablet and MPI Cephalexin® capsule, in healthy Malay ethnic male volunteers in Malaysia.

Material and method: A single dose, randomized, fasting, three-period, three-treatment, three-sequence crossover, open label bioequivalence study was conducted in 24 healthy Malay adult male volunteers, with 1 week washout period. The drug concentration in the sample was analyzed using high performance liquid chromatography.

Result: The mean (SD) pharmacokinetic parameter results of Ospexin® were C_max, 17.39 (4.15) μg/mL; AUC_0–6, 28.90 (5.70) µg/mL?*?h; AUC_0–∞, 30.07 (5.94) µg/mL?*?h; while, those of MPI Cephalexin® tablet were C_max, 18.29 (3.01) μg/mL; AUC_0–6, 30.02 (4.80) µg/mL?*?h; AUC0_0–∞, 31.33 (5.18) µg/mL?*?h and MPI Cephalexin® capsule were C_max, 18.25 (3.92) μg/mL; AUC_0–6, 30.04 (5.13) µg/mL?*?h; AUC_0–∞, 31.22 (5.29) µg/mL?*?h.

Conclusion: The 90% confidence intervals for the logarithmic transformed C_max, AUC_0–6 and AUC_0–∞, of Ospexin® versus MPI Cephalexin® tablet and Ospexin® versus MPI Cephalexin® capsule were between 0.80 and 1.25. Both C_max and AUC met the predetermined criteria for assuming bioequivalence. The pharmacokinetic profile of cephalexin in Malay population does not vary much from other world population.     

Assessment of wellbeing in an indoor office environment

Relationships between indoor building conditions and wellbeing of occupants are complex; many indoor stressors can exert their effects additively or through complex interactions. It has been shown that exposure to these stressors can cause both short-term and long-term effects. Relevant relations between measurements of chemical and physical indoor environmental parameters and effects have been difficult to make. To increase the chance on successful assessment of cause-effect relationships in future indoor environmental quality (IEQ) investigations, there seems to be a need to improve procedures applied to gather the relevant information. From different fields of expertise knowledge was retrieved on how and why people respond to external stressors, which factors, parameters or indicators can be used to explain these responses and how to assess those. No consensus exists on which physical, physiological, psychological or social indicators should be applied to explain these responses. However, several existing techniques are available and promising innovative techniques are being developed, of which the applicability needs to be explored. The review results in a better overview of which factors are important to consider in future studies.     

Egress Efficacy of Persons with Multiple Sclerosis During Simulated Evacuations

Expedited evacuation of commercial and residential structures in the event of an emergency may be more difficult for persons with physical movement disorders. There is a need to better characterize the impact of such disorders and provide movement data to improve evacuee and responder safety. We undertook a pilot, feasibility study that investigated the ability of persons with multiple sclerosis (MS) and controls without MS to walk along a 48 m long path that included five different door configurations with various opening hardware and closure mechanisms, both before and after a six-minute walk, simulating a long evacuation path. Persons with MS took longer to complete the evacuation circuit (102 vs. 31 s) and to pass through each door (average 4.8 vs. 1.4 s) compared to controls. During the six-minute walk, persons with MS had decreased walking speed (0.7 vs. 1.9 m/s). The MS population demonstrated more conservative gait biomechanics throughout the simulation, i.e., wider, shorter and slower steps. Timing and biomechanical differences between populations and the potential fatigue induced through an extended evacuation can be used to improve understanding of movement in populations with disabilities, and incorporate these data into estimation of flow rates during evacuation.     

Approximating the Semantics of Logic Programs by Recurrent Neural Networks

In [1] we have shown how to construct a 3-layered recurrent neural network that computes the fixed point of the meaning function T_P of a given propositional logic program P, which corresponds to the computation of the semantics of P. In this article we consider the first order case. We define a notion of approximation for interpretations and prove that there exists a 3-layered feed forward neural network that approximates the calculation of T_P for a given first order acyclic logic program P with an injective level mapping arbitrarily well. Extending the feed forward network by recurrent connections we obtain a recurrent neural network whose iteration approximates the fixed point of T_P. This result is proven by taking advantage of the fact that for acyclic logic programs the function T_P is a contraction mapping on a complete metric space defined by the interpretations of the program. Mapping this space to the metric space R with Euclidean distance, a real valued function f_P can be defined which corresponds to T_P and is continuous as well as a contraction. Consequently it can be approximated by an appropriately chosen class of feed forward neural networks.