Prednisolone Loaded Tamarind Gum Microspheres for Colonic Delivery

The aim of this work was to formulate a novel multiparticulate system having pH sensitive property and specific enzyme biodegradability for colon specific drug delivery of Prednisolone (PD). Natural polysaccharide, Tamarind gum is used for microsphere preparation and Eudratit S- 100 for coating to provide pH controlled drug release. The formulation aims at minimal degradation and optimum delivery of the drug with relatively higher local concentration, which may provide more effective therapy for inflammatory bowel disease including Crohn disease and ulcerative colitis. Tamarind gum microspheres were prepared by emulsion dehydration technique using polymer in ratio of 1:1 to 1: 9. These microspheres were coated with Eudragit S-100 by oil in oil solvent evaporation method using core: coat ration (5:1). Tamarind gum microspheres and Eudragit coated tamarind gum microspheres were evaluated for surface morphology, particle size and size distribution, percentage drug entrapment, surface accumulation studies, in vitro drug release in simulated gastrointestinal fluids. The effect of various formulation variables were studied the prepared microspheres were spherical in shape in the size range of 64 µm to 113 µm, the encapsulation efficiency was in range of 30-72% depending upon the concentration of gum. The drug release was about 14-20% in first four hours of study gradually rises in 5th hour and 85% drug release occurs in 10-12% hr thus showing desirable drug release in the colonic simulated environment. PD tamarind gum microspheres are thought to have the potential to maintain drug concentration within target ranges for a long time, decreasing the side effects caused by concentration fluctuation, ensuring the efficiency of treatment and improving patient compliance by reducing dosing frequency. The animal study done using acetic acid induced colitis model on rats also suggest the anti inflammatory activity of the formulation.

A double-layer hydrogel based on alginate-carboxymethyl cellulose and synthetic polymer as sustained drug delivery system

A new double-layer, pH-sensitive, composite hydrogel sustained-release system based on polysaccharides and synthetic polymers with combined functions of different inner/outer hydrogels was prepared. The polysaccharides inner core based on sodium alginate (SA) and carboxymethyl cellulose (CMC), was formed by physical crosslinking with pH-sensitive property. The synthetic polymer out-layer with enhanced stability was introduced by chemical crosslinking to eliminate the expansion of inner core and the diffusion of inner content. The physicochemical structure of the double-layer hydrogels was characterized. The drug-release results demonstrated that the sustained-release effect of the hydrogels for different model drugs could be regulated by changing the composition or thickness of the hydrogel layer. The significant sustained-release effect for BSA and indomethacin indicated that the bilayer hydrogel can be developed into a novel sustained delivery system for bioactive substance or drugs with potential applications in drugs and functional foods.

Magneto-Structural Relationship of Tetragonally-Compressed Octahedral Iron(II) Complex Surrounded by a pseudo-S6 Symmetric Hexakis-Dimethylsulfoxide Environment

Since the octahedral high-spin iron(II) complex has the 5T2g ground term, the spin-orbit coupling should be considered in magnetic analysis; however, such treatment is rarely seen in recent papers, although the symmetry-sensitive property is of interest to investigate in detail. A method to consider the T-term magnetism was well constructed more than half a century ago. On the other hand, the method has been still improved in recent years. In this study, the octahedral high-spin iron(II) complex [Fe(dmso)6][BPh4]2 (dmso: dimethylsulfoxide) was newly prepared, and the single-crystal X-ray diffraction method revealed the tetragonal compression of the D4-symmetric coordination geometry around the iron(II) ion and the pseudo-S6 hexakis-dmso environment. From the magnetic data, the sign of the axial splitting parameter, Δ, was found to be negative, indicating the 5E ground state in the D4 symmetry. The DFT computation showed the electronic configuration of (dxz)2(dx2−y2)1(dyz)1(dxy)1(dz2)1 due to the tetragonal compression and the pseudo-S6 environment of dmso π orbitals. The electronic configuration corresponded to the 5E ground term, which was in agreement with the negative Δ value. Therefore, the structurally predicted ground state was consistent with the estimation from the magnetic measurements.

A novel Cd-MOF with enhanced thermo-sensitivity：The rational design, synthesis and multipurpose applications

A novel fluorescent Cd-MOF probe [Cd2(btec)(TPB)0.5(H2O)4]•2H2O (complex 1, TPB = 1,2,4,5-Tetra(4-pyridyl)benzene) have been rationally designed, synthesized and its multipurpose sensing applications have been revealed. Thermo-sensitive property of complex 1 was...

Residual Stresses in Soft Magnetic FeTiB and FeZrN Films Obtained by Magnetron Deposition

The coercive field of soft magnetic ferromagnets is a structure-sensitive property and, in particular, is substantially affected by residual stresses. In the present study, the phase and structural states and residual stresses of the FeTiB and FeZrN films of various compositions, which were prepared by magnetron deposition on glass substrates and subsequent 1-h annealing at temperatures of 200–600 °C, were investigated by X-ray diffraction. The formation of a nanocrystalline structure is observed. It comprises different phases having different lattice parameters and unit-cell volumes and is characterized by high level of microstrains of grains as well; the microstrains predetermine the formation of high compressive stresses in the deposited films. As the annealing temperature increases, the compressive stresses decrease, and, at certain temperatures, gradually the films transform into thermal tensile stresses, which are induced by the difference in the thermal expansion coefficients of the film and substrate. Thus, the heat treatment is the efficient way to improve the soft magnetic properties of the studied class of film materials produced by magnetron deposition.

Smart properties of carbon nanotube-epoxy composites

Intelligent smart materials can not only monitor the damage and degradation of architectural structures in real time but also the health structure. In recent years, carbon nanotubes materials have emerged to possess both excellent mechanical and electrical properties. Moreover, when carbon nanotubes are added to epoxy resin, intelligent composite materials with significant sensitivity are created. In this study, the stress–strain curves and anelasticity of carbon nanotube/epoxy resin composites with different carbon nanotube concentrations is analyzed. Through changing the level of carbon nanotubes using the two-pole method, the percolation threshold of carbon nanotube/epoxy composites was determined. Thereafter, the effect of temperature on the composites’ conductive properties was investigated. Moreover, using the stepwise cyclic loading method, the piezoresistivity of the carbon nanotube/epoxy composites was investigated. The test results show that the elastic limit, the yield point, and the elastic modulus range of the carbon nanotube/epoxy composites is approximately 45 MPa, 50 MPa, and 1–2 GPa, respectively. The anelasticity of the carbon nanotube/epoxy composites increases with the gradual increase of the stress level. The percolation threshold interval of carbon nanotube/epoxy composites ranges from 0.5 to 1.0 wt%. The rate of change of resistance for the different concentrations on carbon nanotube/epoxy specimens corresponds to the temperature. Notably, the carbon nanotube/epoxy composites have better discrimination and pressure sensitivity for different grades of load. When the carbon nanotube content is 0.5 wt%, the sensitivity of the carbon nanotube/epoxy composites pressure-sensitive property is the largest, which is in agreement with the threshold curve. The results of this investigation have implications for the application of carbon nanotube/epoxy composites in structural health monitoring.

Depth-dependent soil mixing persists across climate zones

Soil mixing over long (>102 y) timescales enhances nutrient fluxes that support soil ecology, contributes to dispersion of sediment and contaminated material, and modulates fluxes of carbon through Earth’s largest terrestrial carbon reservoir. Despite its foundational importance, we lack robust understanding of the rates and patterns of soil mixing, largely due to a lack of long-timescale data. Here we demonstrate that luminescence, a light-sensitive property of minerals used for geologic dating, can be used as a long-timescale sediment tracer in soils to reveal the structure of soil mixing. We develop a probabilistic model of transport and mixing of tracer particles and associated luminescence in soils and compare with a global compilation of luminescence versus depth in various locations. The model–data comparison reveals that soil mixing rate varies over the soil depth, with this depth dependency persisting across climate and ecological zones. The depth dependency is consistent with a model in which mixing intensity decreases linearly or exponentially with depth, although our data do not resolve between these cases. Our findings support the long-suspected idea that depth-dependent mixing is a spatially and temporally persistent feature of soils. Evidence for a climate control on the patterns and intensities of soil mixing with depth remains elusive and requires the further study of soil mixing processes.

Stabilization of microhardness of hard alloy VK6 cutting plates modified by fast electrons by cryoprocessing

The study is devoted to the effect cryoprocessing has on the stabilization of VK6 (hard alloy) after irradiation with fast electrons with energy of 5 MeV. To investigate samples with a close microstructure characteristics, a measurement of a structure-sensitive property -- co-effective force -- was held. It was shown that the treatment of VK6 hard alloy with fast electron irradiation increases its microhardness by 30 % in comparison with the original samples without any irradiation. It was found out that the microhardness of VK6 hard alloy samples after treatment with fast electrons depends on the initial surface structure, so that polished samples have higher values of microhardness than samples which surface were ground. X-ray phase analysis made it possible to establish the difference between the structures of polished and ground surfaces of the VK6 hard alloy in a stressed state. It was also shown that the treatment with fast electrons irradiation with an energy of 5 MeV does not lead to the formation of new phases. To establish the consolidation of the effect of increasing the hardness of the irradiated materials, annealing of VK6 hard alloy samples at the temperature of 30–100 °C (on air) was held. Cryoprocessing allowed us to consolidate the effect of increasing microhardness of the surface (surface microhardness) and wear resistance after irradiation of the VK6 hard alloy. Ill. 5. Ref. 10.