Symbolic model checking composite Web services using operational and control behaviors

This paper addresses the issue of verifying if composite Web services design meets some desirable properties in terms of deadlock freedom, safety (something bad never happens), and reachability (something good will eventually happen). Composite Web services are modeled based on a separation of concerns between business and control aspects of Web services. This separation is achieved through the design of an operational behavior, which defines the composition functioning according to the Web services’ business logic, and a control behavior, which identifies the valid sequences of actions that the operational behavior should follow. These two behaviors are formally defined using automata-based techniques. The proposed approach is model checking-based where the operational behavior is the model to be checked against properties defined in the control behavior. The paper proves that the proposed technique allows checking the soundness and completeness of the design model with respect to the operational and control behaviors. Moreover, automatic translation procedures from the design models to the NuSMV model checker’s code and a verification tool are reported in the paper.     

Optimization of Citric Acid Production from a New Strain and Mutant of Aspergillus niger Using Solid State Fermentation

A new strain of Aspergillus niger isolated from soil and its mutant were used for citric acid production from carob under solid-state fermentation conditions. The parental strain produced 30 g/kg citric acid, while the mutant G4, selected after four rounds of gamma ray irradiation, produced 60 g/kg. Maximum citric acid production was obtained after 7 days of incubation, as the acid production was 34 and 64 g/kg for parental and mutant strains, respectively. The addition of 2% methanol increased citric acid production from the parental strain to 42 and the mutant G4 to 65 g/kg. Trace elements, namely Cu, Fe, and Zn, promoted the production of citric acid as the acid production from the parental strain increased to 46 g/kg and for mutant G4 increased to 73 g/kg after their addition. The optimum spore inoculum concentration for acid production was 10⁷ ml^-1, and the optimum pH was 5 for both parental and mutant strains.     

Development of macroporous calcium phosphate scaffold processed via microwave rapid drying

Porous hydroxyapatite (HA) scaffold has great potential in bone tissue engineering applications. A new method to fabricate macroporous calcium phosphate (CP) scaffold via microwave irradiation, followed by conventional sintering to form HA scaffold was developed. Incorporation of trisodium citrate dihydrate and citric acid in the CP mixture gave macroporous scaffolds upon microwave rapid drying. In this work, a mixture of β-tricalcium phosphate (β-TCP), calcium carbonate (CaCO₃), trisodium citrate dihydrate, citric acid and double distilled de-ionised water (DDI) was exposed to microwave radiation to form a macroporous structure. Based on gross eye examinations, addition of trisodium citrate at 30 and 40 wt.% in the CP mixture (β-TCP and CaCO₃) without citric acid indicates increasing order of pore volume where the highest porosity yield was observed at 40 wt.% of trisodium citrate addition and the pore size was detected at several millimeters. Therefore, optimization of pore size was performed by adding 3–7 wt.% of citric acid in the CP mixture which was separately mixed with 30 and 40 wt.% of trisodium citrate for comparison purposes. Fabricated scaffolds were calcined at 600 °C and washed with DDI water to remove the sodium hydroxycarbonate and sintered at 1250 °C to form HA phase as confirmed in the X-ray diffraction (XRD) results. Based on Archimedes method, HA scaffolds prepared from 40 wt.% of trisodium citrate with 3–7 wt.% of citric acid added CP mixture have an open and interconnected porous structure ranging from 51 to 53 vol.% and observation using Scanning electron microscope (SEM) showed the pore size distribution between 100 and 500 μm. The cytotoxicity tests revealed that the porous HA scaffolds have no cytotoxic potential on MG63 osteoblast-like cells which might allow for their use as biomaterials.     

Sequence analysis of a cryptic plasmid from Flavobacterium sp. KP1, a psychrophilic bacterium

A cryptic plasmid found at high copy number was isolated from Flavobacterium sp. KP1, a psychrophilic Gram-negative bacterium, cloned, and sequenced. The sequence will appear in the DDBJ/EMBL/GenBank databases under the accession number AB007196. The pFL1 plasmid is 2311 nucleotides in length with 32.7% GC content, and shows a distinctive nucleotide sequence without homology to other plasmids of similar length. The plasmid contains two open reading frames of significant length, ORFI and ORFII. ORFI encodes a protein similar to the replication proteins found in Gram-negative bacterial plasmids, Bacteroides fragilis plasmid pBI143 and Zymomonas mobilis plasmid pZM2. The putative translation product of ORFII shows homologies with plasmid recombination proteins found mainly in Gram-positive bacterial plasmids such as Staphylococcus aureus plasmid pT181.     

Hydrothermal preparation of high saturation magnetization and coercivity cobalt ferrite nanocrystals without subsequent calcination

In this work, CoFe₂O₄ nanocrystals with high saturation magnetization (M_s) and high coercivity (H_c) have been fabricated via a simple hydrothermal method and without subsequent calcination. The resulting CoFe₂O₄ nanocrystals are characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectrometry, differential scanning calorimetry and vibrating sample magnetometry. The results indicate that CoFe₂O₄ nanocrystals are single crystal and the average crystallite size is increasing with the hydrothermal temperature. The electron micrographs show that the nanocrystals are well-dispersed and possess uniform size. The shape of CoFe₂O₄ nanocrystals is transformed from spherical into rod by increasing the hydrothermal temperature. The nanocrystals show relatively high M_s of 74.8 emu g⁻¹ and H_c of 2216 Oe, as compared to previous reported results. The obtained results reveal the applicability of this method for efficiently producing well crystallized and relatively high magnetic properties CoFe₂O₄ nanocrystals as compared to other methods. More importantly, it does not require further calcination processes.     

Measurement of neutron capture cross-section of the Ga(n, γ)Ga reaction at 0.0536 eV energy

The neutron capture cross-section for the ⁷¹Ga(n,  γ)⁷²Ga reaction at 0.0536 eV energy was measured using activation technique based on TRIGA Mark-II research reactor. The ¹⁹⁷Au(n, γ)¹⁹⁸Au monitor reaction was used to determine the effective neutron flux. Neutron absorption and γ-ray attenuation in gallium oxide pellet were corrected in determination of cross-section. The cross-section for the above reaction at 0.0536 eV amounts to 2.75 ± 0.14 b. As far as we know there are no experimental data available at our investigated energy. So far we are the first, who carried out experiment with 0.0536 eV neutrons for cross-section measurement. The present result is larger than that of JENDL-3.3, but consistent within the uncertainty range. The value of ENDF/B-VII is higher than this work. The result of this work will be useful to observe energy dependence of neutron capture cross-sections.     

Swelling properties of copolymeric hydrogels prepared by gamma irradiation

Crosslinked xerogels in the form of rods have been prepared to > 99.9% conversion by the γ-ray initiated copolymerization in vacuo ob n-butyl acrylate (BA) with N-vinyl-2-pyrrolidone (VP) in the presence and absence of a crosslinking agent. Thin (about 0.5 mm) disks were swollen in water at 21°C, the final equilibrium swelling being the true water content only for copolymers of high BA content. At low-medium BA content, swelling was accompanied by the release of a small water-soluble fraction, leading to a slightly reduced apparent value for the water content. True water contents could be obtained more rapidly by prior Soxhlet extraction with boiling water. For xerogels containing > about 75% VP by weight, the resultant hydrogels had water contents > about 80%. The influences of dose, dose rate copolymer composition, and concentration of crosslinker on the water content, sol fraction, and extension ratio were investigated. A high level of reproducibility in properties of the hydrogels was obtained by numerous replicate experiments. The feasibility of scaling up the preparation to produce long (60 cm) xerogel rods of uniform properties has been demonstrated. For these copolymers, swelling in several common organic solvents generally exceeds that in water.     

Purity of crosslinkers for polymeric hydrogel preparation

Chromatographic procedures are described for purifying and assessing the purity of two crosslinking agents commonly used in the preparation of polymeric hydrogels. Densities and refractive indices at different temperatures are reported for these materials.     

A novel double-circuit-rotor balanced induction motor for improvedslip-energy recovery drive performance. II. Experimental verificationand harmonic analysis

The merits of the new slip-energy recovery drive system that has been proposed in Part I of this paper (see ibid., vol.11, no.3, p.556-62, 1996) is demonstrated here. Experimental work is carried out to verify the simulated, models of the proposed and conventional systems. Furthermore, harmonic analysis of both systems is conducted analytically and confirmed numerically using the FFT. The main feature of the new proposed system is the significant reduction in the harmonics of the rotor flux linkage. This leads to substantial reductions in the stator current harmonics. Moreover, the pulsating components in the developed electromagnetic torque are also reduced significantly in the new proposed system