An investigation of the structural and dielectric properties of the solid solution system (1-x) Pb(Sc1/2Ta1/2)O3 -(x) PbTiO3

The preliminary characterization of the structural and dielectric properties of compositions from the solid solution system (1-x) Pb(Sc1/2Ta1/2)O3-(x) PbTiO3 is presented. A morphotropic phase boundary between rhombohedral (pseudocubic) and tetragonal compositions is observed to exist between x =0.4 and x = 0.45. A wide range of dielectric response is exhibited by the various compositions investigated ranging from the diffuse dispersive response characteristic of relaxor -type ferroelectrics to the sharp K(T) response associated with normal ferroelectrics. A high dielectric constant maximum is observed for all compositions with a peak K(max) of 33000 occurring for x=0.4.     

Preformulation Studies III - Vasicinone - a Bronchodilatory Alkaloid from Adhatoda Vasica Nees (Absorption, Potency and Toxicity Studies)

Bronchodilatory activity of pure samples of vasicinone hydrochloride is investigated and compared with isoprenaline and aminophylline. Acute toxicity in mice and absorption pattern in dogs of aqueous solution administered by different routes is studied. The studies confirm the activity and safety of vasicinone and its potentiating effect on bronchodilatory activity of aminophylline.     

Influence of calcium content of biomass-based materials on simultaneous NOx and SO2 reduction

Pyrolysis products of biomass (bio-oils) have been shown to cause a reduction in NOx emissions when used as reburn fuels in combustion systems. When these bio-oils are processed with lime, calcium is ion-exchanged and the product is called BioLime. BioLime, when introduced into a combustion chamber, pyrolyzes and produces volatile products that reduce NOx emissions through reburn mechanisms. Simultaneously, calcium reacts with SO2 to form calcium sulfate and thus reduces SO2 emissions. This paper reports the characterization of composition and pyrolysis behavior of two BioLime products and the influence of feedstock on pyrolysis products. Thermogravimetric analysis (TGA) and 13C-CP/MAS NMR techniques were used to study the composition of two biomass-based materials. The composition of the pyrolysis products of BioLime was determined in a laboratory scale flow reactor. The effect of BioLime composition on NOx and SO2 reduction performance was evaluated in a 146.5 kW pilot-scale, down fired combustor (DFC). The effect of pyrolysis gas composition on NOx reduction is discussed. The TGAweight loss curves of BioLime samples in an inert atmosphere showed two distinct peaks corresponding to the decomposition of light and heavy components of the BioLime and a third distinct peak corresponding to secondary thermal decomposition of char. The study also showed that BioLime sample with lower content of residual lignin derivatives and lower calcium content produced more volatile compounds upon pyrolysis inthe combustor and achieved higher NOx reduction (15%). Higher yields of pyrolysis gases increased the NO reduction potential of BioLime through homogeneous gas phase reactions. Calcium in BioLime samples effectively reduced SO2 emissions (60-85%). However, addition of higher calcium content to the BioLime samples also appeared to inhibit the volatile yield and thereby lowered the NOx reduction.     

Federated identity management

Most confidential, valuable resources on the World Wide Web are protected by some form of authentication technology. To access these resources, either via the public Internet or private intranets, users must verify their digital identity. This can range from a simple user-name-password combination to biometric data such as fingerprints to physical objects like hardware tokens and smart cards. Federated identity management would enable individuals to interact with various service providers or Web sites with trust relationships by signing in just once.     

Polar glass ceramics — A new family of electroceramic materials: Tailoring the piezoelectric and pyroelectric properties

Grain oriented multicomponent polar glass-ceramics have been prepared by crystallizing the glasses in a temperature gradient. Inexpensive, large area piezoelectric and pyroelectric devices can be fabricated by this method, and by adjusting the composition of the glasses and crystallization conditions, it is possible to tailor the properties to meet device requirements. Based on the growth characteristics and the connectivity pattern of the crystallites, the piezoelectric, pyroelectric and dielectric properties of glass-ceramic composites can be predicted. Two examples discussed in this paper are piezoelectric glass-ceramics which are not pyroelectric, and pyroelectric glass-ceramics which are not piezoelectric.     

Incommensurate phases in the system Ba2TiSi2O8-Ba2TiGe2O8

Incommensurate phases and phase transitions in fresnoite-type crystals: Ba₂TiSi₂O₈, Ba₂TiGe₂O₈, and compositions in the system Ba₂TiSi₂O₈-Ba₂TiGe₂O₈, are discussed.     

Temperature dependence of the dielectric constant of KMnF3

Precise and careful measurements of capacitance vs temperature on KMnF₃ single crystals are made. The results indicate the stronger interaction of the soft mode with the acoustic modes in KMnF3 compared to that in SrTiO3 which is evident from the anomaly in the dielectric constant at the transition temperature.