Bipolar magnetic microsensor for longitudinal fields

In this paper, we introduce a novel bipolar magnetic sensor for a field parallel to surface. It is designed in standard integrated bipolar technology and it consists of a pair of identical vertical n-p-n transistors anti-symmetrically oriented, whose bases are made up of two diffusions with different depths. Each transistor practically is made up of two structures connected in parallel. The only difference between them consists in different thickness and impurity concentration within the base.

High sensitivity, low offset, and high linearity over large ranges of the magnetic field induction are obtained.     

Microstructure and properties of epitaxial Sr<Subscript>2</Subscript>FeMoO<Subscript>6</Subscript> films containing SrMoO<Subscript>4</Subscript> precipitates

Thin films of Sr₂FeMoO₆ (SFMO) were grown by pulsed laser deposition in non-optimized argon ambient pressures. The films were found to contain a high number of precipitates of foreign phases. The nature and microstructure of these phases were investigated in detail by high-resolution scanning transmission electron microscopy (STEM) and X-ray diffractometry (XRD). We found out that the dominant foreign phase embedded in the SFMO film matrix was SrMoO₄ (SMO). Through STEM and XRD analysis, we determined that the SMO phase grows epitaxially with respect to the surrounding SFMO matrix and has a fairly good crystallinity. Although the SFMO films include many foreign precipitates, they still exhibit good conducting properties and moderate magnetization values. Tuning the growth of the SMO phase on top of SFMO films to obtain a natural tunnel barrier might pave the way for future applications of SFMO in spintronic devices.     

Nostoc Linckia as Biosorbent of Chromium and Nickel from Electroplating Industry Wastewaters

The present study relates to the use of cyanobaeterium Nostoc linkia for removal of chromium and nickel from wastewater of galvanic industry. To determine concentrations of Cr and Ni in wastewater samples atomic absorption spectrometry was used. The samples of dried nostoc biomass after exposure to wastewater were subject to nondestructive instrumental neutron activation analysis. During 30 rain of the contact ofbiomass with wastewater 84% of chromium was removed from the wastewaters. Beside chromium after 30 rain nostoc biomass accumulates the amount of iron and zinc that exceeds their concentrations in the control biomass samples by a factor of 6 and 8, respectively. Nickel content in biomass after interaction with Cr-containing wastewater increases sixty fold and copper-sixteen fold. During the same time of biomass-Ni-containing wastewater interaction, 50% of nickel were accumulated. The method of Fourier transform infrared spectroscopy was applied to identify functional groups responsible for metal binding.     

In vitro antioxidant capacity of honeybee-collected pollen of selected floral origin harvested from Romania

Total phenolic phytochemical concentration was measured in 12 honeybee-collected pollens of selected floral species as well as their antioxidant capacity. The content of total polyphenols was measured spectrophotometrically using the Folin–Ciocalteu reagent with gallic acid as standard. The antioxidant properties were evaluated by 2,2-diphenyl-picrylhydrazyl radical scavenging capacity (DPPH) assay, Trolox equivalent antioxidant Capacity procedure and Ferric ion reducing antioxidant power assay. A great variability regarding the correspondence between the antioxidant activity and the content of total polyphenols of honeybee-collected pollens with different botanical origin was found. Antioxidant activities were different for each floral species and were not clearly associated to their total phenolic content.     

Synergism in mixed monolayers of alkylpolyglucoside and alkylsorbitan surfactants at liquid/liquid interface

A study of nonideal behavior in the formation of mixed monolayers at the oil-water interface was performed for a nonionic-nonionic surfactant system. Mixtures containing alkylpolyglucoside and alkylsorbitan derivatives were investigated. As the oily phase, colza-rapeseed and olive oils were used. To evidence a synergetic effect in the interfacial tension reduction in the oil-water-surfactant-cosurfactant system, the model based on the regular solution theory was modified for the case of both surfactants being soluble in the water as well as in the oily phase. For determination of the condition for the synergism and the point of the maximum synergetic effect, the molar fraction in the mixed monolayer X ^s and the interaction parameter β^s were calculated, using experimental data for the interfacial tension and for the partition coefficient. A set of general equations was developed, to allow the analysis of a mixture containing a water-soluble and an oil-soluble surfactant. The equations are applied according the characteristics of studied quaternary systems. The mathematical model was tested with literature data, and the results were compared with those obtained from the phase diagram of oil-water-mixed surfactant system. The systems water-vegetable oil-alkylpolyglucoside-alkylsorbitan show a maximum synergetic effect at molar fractions between 0.85 and 0.90. The liquid-liquid interfacial tension and partition coefficient data were used to calculate the point of the maximum synergetic effect, i.e., the surfactant-cosurfactant ratio, which ensures the interfacial tension miniumum. The dramatic reduction in interfacial tension due to the presence of the surfactant mixture at the interface at the point of the synergism maximum is related to the formation of three-phase and single-phase microemulsions. The results were applied to obtain single-phase microemulsion in water-vegetable oil-alkylpolyglucoside-alkylsorbitan systems.     

ZnS stacking order influence on the formation of Zn-poor and Zn-rich Cu2ZnSnS4 phase

This paper reports the synthesis and characterization of Cu₂ZnSnS₄ (CZTS) absorber films, prepared by a two-step electrodeposition of a ZnS (zinc sulfide) binary and a CZT (copper, zinc and tin) ternary precursors on Mo/Ti/Si substrates. The as-electrodeposited ZnS/CZT and CZT/ZnS stacks were thermally treated in a tubular furnace in sulfur environment at 550 °C. The role of the ZnS buffer layer is to provide a zinc and sulfur reservoir, needed to complete the formation of kesterite phase. X-ray diffraction and Raman analyses revealed the formation of the CZTS phase. The surface morphology and chemical composition of the films were studied using a scanning electron microscope. The bandgap values inferred from diffuse reflectance data, are discussed with respect to the stoichiometry which is considerably affected by the order of the stacks. Room-temperature photoluminescence of the CZT/ZnS sample showed a board PL band of 1.51 eV. It was found that the film with a ZnS layer on top is preferred for the formation of a Zn-rich single CZTS phase.

     

Generic platform for registration and online offering of assistance-on-demand (AoD) services in an inclusive infrastructure

Universal Access in the Information Society - An increasing percentage of the population needs assistance services for a wide range of activities related to their independent living, which can be...     

Fabrication of hydrophobic and antireflective coatings based on hybrid silica films by sol–gel process

This paper reports the synthesis of hydrophobic and antireflective coatings by sol–gel process at room temperature (25 °C), using tetraethylorthosilicate (TEOS) as a precursor and methyltriethoxysilane (MTES), phenyltriethoxysilane (PTES), vinyltriethoxysilane (VTES), and octyltriethoxysilane (OTES) as surface modifying agents. The silica sol was prepared by keeping the molar ratio of TEOS:RTES at 1:1, in acidic conditions with ethanol and 0.1 M HCl. All hybrid systems were enriched with titanium(IV) isopropoxide as the cross-linking agent. It was observed that the obtained silica films become hydrophobic with the introduction of the hydrophobic organic group. The higher value of static water contact angle (107 ± 3°) was obtained for the silica film prepared with TEOS + OTES. Under optimal synthesis condition, we obtained antireflection coatings, exhibiting a low reflection in the visible range.     

The study of the electric and magnetic properties of PbZr0.2Ti0.8O3-BiFeO3 multilayers

The results of the electric and magnetic measurements performed on PbZr_0.2Ti_0.8O₃-BiFeO₃ symmetric structures, deposited on Pt/Si wafers, were compared for different number of layers in order to analyse the effect of interfaces over the macroscopic properties. It was found that the shape and magnitude of the capacitance-voltage characteristic, as well as the shape and parameters of the ferroelectric and magnetic hysteresis, depend on the number of interfaces in the intended multilayer structure. A temperature induced gradual transition from a magnetically disordered spin glass like phase of low temperature to an uncompensated antiferromagnetic phase at room temperature takes place in the BiFeO₃ films, under low applied magnetic fields. A partial ferromagnetic like order can be obtained at low temperatures by increasing the field. The observed changes in the electric and magnetic behaviour of the systems were related to an increased degree of disorder for electric dipoles and magnetic moments, due to the increased number of layers and crystallization treatments.     

Study of the atypical formations in the corrosion bulks of an ancient bronze shield,by optical and electron microscopy

This article presents the atypical formations in the structure of the corrosion crust and in the partially mineralized metallic core, which resulted during the underground stay of a bronze shield, dated between the 1st century B.C. and the 1st century A.D. For our study, we choose a representative fragment from the rim of the shield, which was analyzed by optical microscopy and by electron microscopy coupled with energy‐dispersive X‐ray spectroscopy, to study its morphology, its composition, and the location of chemical compounds on the surface and inside the bulk formed during the underground stay, by processes of chemical and physical alteration, assisted by contamination with structural elements from the site. Those processes, by monolithization and mineralization formed a series of structures consisting of congruent elements and phases with a complex composition. Those formations, defined as surface effects generated by exogenous factors and endogenous factors inside the bulk, are frequently found in ancient bronze objects (such as the exterior flat mole formations and the Liesegang effect in the stratigraphic structure of the bulk). Some of those structures have atypical characteristics as regards their structure, composition, and formation mechanism, which may be used in archeometry. Moreover, that includes the object in the category of special cases, in terms of artifact evolution during underground stay and of the atypical formations resulted from the action of pedological and environmental factors. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.