The infrared absorption and dielectric properties of Li–Ga ferrite

The investigated compositions of the Li–Ga ferrite system Li_0.5Fe_2.5−xGa_xO₄ (where x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) were studied by means of infrared (IR) spectroscopy. The analysis of IR spectra indicates the presence of splitting in the absorption band due to the presence of Fe²⁺ ions in ferrite. The dielectric constant ′, the dielectric loss ″ and the loss tangent tan δ were measured at elevated temperatures ranging from room temperature up to 850 K as a function of frequency (f = 10²–10⁶ Hz) for the investigated compositions. Maximum peak in tan δ and inverse peaks in ′ appeared for some samples due to the resonance phenomenon. The obtained data were discussed based on the valence exchange between (Fe³⁺ and Fe²⁺) and (Ga³⁺ and Ga²⁺), i.e. hopping mechanism.     

Adsorption of sodium dodecyl sulfate, Triton X100 and their mixtures to shale and sandstone: A comparative study

In this paper, batch experiments of sediment/aqueous systems were conducted to evaluate the adsorption of SDS, TX100 and their mixtures (1:2; 1:1 and 2:1 SDS:TX100 mass ratio) onto local shale and sandstone. Adsorption of surfactants was assessed using a surface tension technique for surfactant concentrations less than surfactant monomer saturation (CMC). It is shown that the amount of TX100 adsorbed to shale (7.5 g/kg) are greater than those adsorbed to sandstone (1.5 g/kg). SDS showed negligible affinity for adsorption on both adsorbents. The amounts of both TX100 adsorbed to shale or sandstone can be decreased and minimized when they are mixed with SDS. While adsorption of TX100–SDS mixtures on shale reduced to 4.5 g/kg (40% reduction in comparison to adsorption of TX100), adsorption to sandstone decreased tremendously to 0.3 g/kg (80% reduction in comparison to adsorption of TX100). Furthermore, micellization behavior was assisted through mixing. CMCs of mixtures reduced to 0.1 wt.% in presence of shale compared to 0.15 wt.% for TX100 and 0.1 wt.% for SDS. Similarly, CMC of mixtures reduced to 0.03 wt.% in presence of sandstone in comparison to 0.05 for pure TX100 and 0.1 wt.% for SDS. Because of their ability to minimize amounts adsorbed in different adsorbents, mixed anionic–nonionic surfactant particularly TX100–SDS may show potential advantages in SEAR and EOR applications.     

Development and Characterization of Gentamicin-Loaded Arabinoxylan-Sodium Alginate Films as Antibacterial Wound Dressing

Biopolymer-based antibacterial films are attractive materials for wound dressing application because they possess chemical, mechanical, exudate absorption, drug delivery, antibacterial, and biocompatible properties required to support wound healing. Herein, we fabricated and characterized films composed of arabinoxylan (AX) and sodium alginate (SA) loaded with gentamicin sulfate (GS) for application as a wound dressing. The FTIR, XRD, and thermal analyses show that AX, SA, and GS interacted through hydrogen bonding and were thermally stable. The AXSA film displays desirable wound dressing characteristics: transparency, uniform thickness, smooth surface morphology, tensile strength similar to human skin, mild water/exudate uptake capacity, water transmission rate suitable for wound dressing, and excellent cytocompatibility. In Franz diffusion release studies, >80% GS was released from AXSA films in two phases in 24 h following the Fickian diffusion mechanism. In disk diffusion assay, the AXSA films demonstrated excellent antibacterial effect against E.coli, S. aureus, and P. aeruginosa. Overall, the findings suggest that GS-loaded AXSA films hold potential for further development as antibacterial wound dressing material.     

Controlled growth and composition of multivariate metal-organic frameworks-199 via a reaction-diffusion process

In this paper,we exploit our prior successful synthesis of MOF-199 single crystals using the reaction-diffusion framework(RDF),to synthesize multivariate metal-organic frameworks(MTV-MOFs)version with enhanced properties.The MTV-MOFs are synthesized by creating defects within the MOF-199 crystal structure by integrating organic linkers entailing different functional groups.Accordingly,5-aminoisophthalic acid(NH₂-BDC)and 5-hydroxyisophthalic acid(OH-BDC)are separately mixed with 1,3,5-benzenetricarboxylic acid(BTC)in three different starting ratios of X-BDC:BTC(1:3,1:1)and(3:1).The effects of this linker on the morphology of the synthesized MTV-MOFs,their thermal stability,and their surface area are investigated.The extent of the incorporation of the linkers in the framework is elucidated via¹H-NMR spectroscopy and it is shown that the incorporation varies as a function of the location along the tubular reactor,a characteristic of RDF.The enhanced properties of the synthesized MTV-MOFs are further demonstrated by measuring its adsorptive capability for methylene blue(MB)and rhodamine B(Rh B)in aqueous solution,and compared with that of the as-synthesized MOF-199.The kinetic and thermodynamic studies reveal that MTV-MOFs with the ratio of X-BDC:BTC(1:1)exhibit the best uptakes of MB(263 mg/g)for X=OH and Rh B(156 mg/g)for X=NH₂.The adsorbents are also easily regenerated for three consecutive cycles without losing their efficiency.We finally demonstrate that MTV-MOFs can be designed to tune the dye removal selectivity and enhance the removal capacity of both MB and RhB in a binary aqueous solution of these dyes.     

Preparation of nonwoven mats of electrospun poly(lactic acid)/polyaniline blend nanofibers: A new approach

The preparation of nonwoven mats of electrospun poly(lactic acid)/polyaniline (PANI) blend nanofibers faces some critical challenges that will be addressed in the present work. The challenges are in achieving high and adjustable content of PANI while keeping the spinnable solution nonagglomerated with no need to further filtration that might lead to wrong estimation of PANI content in the mat. We report an unprecedented content of 40% wt of PANI that is achieved using a new two‐step procedure. It is based on: (1) the preparation of the spinnable solution from a friable nonagglomerated and readily dispersible PANI: ‐TSA powder and (2) the use of an optimized mixture of ‐cresol/dichloromethane. The obtained nanofiber mats are characterized by FTIR and UV–vis spectroscopy. The morphology and the thermal stability of the nanofibers are investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The amorphous structure of the nanofibers is verified using XRD measurements. The DC‐conductivity of these blend nanofibers is found to be far larger than the published DC‐conductivity values for blend nanofibers of PANI with PLLA or with other polymers. This is attributed to the high content of PANI in the blend and to the role played by ‐cresol as a secondary dopant. The investigation of the aging effect on the DC‐conductivity reveals an exponential decrease with a characteristic time of weeks. The electrical impedance spectroscopy (EIS) shows a pure ohmic behavior of the blend mat. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43687.     

Dehydration by Successive Pressure Drops for Drying Paddy Rice Treated by Instant Controlled Pressure Drop

The aim of the present work was to study the application of the dehydration by successive pressure drops (DDS) process to different varieties of paddy rice initially treated by the instantaneous controlled pressure drop (DIC), which is a high-temperature, short time postharvest treatment (moisture content about 20–25% dry basis) and takes less than 30 s. DIC paddy rice is dried by DDS in a relatively short time and a high milling quality is obtained (12–13% db in about 2 h). The final rice is white, easily distinguishing it from the standard parboiled one. Without a tempering period, DDS rice has less than 3% of broken grains, with a high organoleptic quality (preservation of the natural aroma with a firm and non-sticky texture), and the cooking time of both brown (whole) and white DIC rice is very short (15 and 7 min, respectively).     

Réseau cylindrique microruban à 12 GHz

A 200-patch, 60°-extend cylindrical array, working around 12 GHz was built with a triangular lattice repartition. The feeding manner used, consisting in the feed of two adjacent patches by the same network access, helps simplifying this network. The effect of this manner on the radiation pattern is demonstrated for different excitations with a satisfactory agreement between computation and measurement.     

Abstraction database concept for engineering modeling

Engineering modeling and design generally involve a large set of independent but interrelated data items. One way to organize and store these data items in a systematic and consistent manner is through the use of a database management system. The abstraction concepts of aggregation and generalization provide a powerful mechanism for organizing and structuring engineering data. The invariants required to maintain the abstract data model are examined in this paper. Integrity issues involved in the data representation of hierarchically structured engineering models, such as constructive solid geometry models, are discussed. Object-oriented programming concepts are used to implement a prototype integrity subsystem for enforcement of integrity constraints in the aggregation/generalization framework for modeling data.     

Work flow methodology : A proposed approach for analysis and conceptual design of large scale computer based information systems

The objective of this paper is to explain our approach called “Work Flow Methodology for Analysis and Conceptual Data Base Design of Large Scale Computer Based Information System”. The user fills in, through the different steps of the methodology and in the light of the definition of dynamic adaptive system, a number of forms which relate the topological dimension to the time dimension for each application of a given system. In addition, we obtain the “Unit Subschema” which defines the responsibilities of issuing and authorization of receiving information at the proper time. Finally, we apply our methodology to the Registration System in Kuwait University.