A Monte Carlo study of spring-exchange magnets containing ultra-high coercive phases

The aim of the present work is to study magnetization processes in the spring-exchange magnetic composites containing magnetically soft, hard and ultra-high coercive phases, experimentally found in Tb-Fe-B-Nb group of alloys. In order to modeling hysteresis loops a special Monte Carlo procedure,suitable for irregular geometry of the composites, was applied. The obtained results indicate that sufficiently strong coupling between soft and hard magnetic phase leads to collective, single-phase-like movement of such phases, which in turn, causes increase of the coercivity and internal magnetic energy.     

Corneal involvement in epidermolysis bullosa simplex

A 17-year-old boy and his mother represent the first reported cases of ocular (corneal) involvement of the simplex form of epidermolysis bullosa. Both had a ring-like configuration of fine bullous lesions in the midperiphery bilaterally at the level of deep corneal epithelium superficial to Bowman's membrane (basal cell layer), with the son manifesting symptoms when some of his bullae ruptured through to the corneal epithelial surface. Nonscarring blistering was present in three generations of this family, suggestive of dominantly inherited epidermolysis bullosa simplex, and was confirmed by electron microscopy of a skin specimen from the son. Thus, ocular involvement has now been observed in all of the major types of epidermolysis bullosa.     

Combining laser chemical processing and aerosol jet printing: a laboratory scale feasibility study

First results showing the viability of combining laser chemical processing (LCP) and aerosol jet printing (AJP) technologies to produce a high‐efficiency front side for silicon solar cells are presented. LCP simultaneously opens the anti‐reflection coating (ARC) and highly dopes the underlying silicon to create a selective emitter, while AJP is the first in a two‐step fine‐line contact formation procedure. The electrical properties as well as the morphology of the resulting structures are presented. Performance similar to that achieved with evaporated TiPdAg metallization is demonstrated. Copyright © 2010 John Wiley & Sons, Ltd.     

Detecting endocrine-disrupting compounds by fast impedance measurements

The increasing concern worldwide over the adverse effects of endocrine disruptors on human health has created a need for screening systems to detect xenoestrogens, a diverse group of environmental chemicals that mimic estrogenic actions and are hypothesized to decrease male fertility. Here, we describe a novel, class-selective detector that uses fast impedance measurements to monitor the binding of estrogen and xenoestrogens to a native estrogen receptor. We embedded the receptor in synthetic lipid bilayers attached to gold electrodes. The lipid bilayers serve as electrical circuits constructed of resistors and capacitors. Estrogen binding to the receptor-modified electrode is immediately followed by conformational changes in the lipid layer, leading to alterations of the electrical circuit components that are detected by fast impedance measurements. The electrochemical system enabled characterization of changes in the bilayer structure and quantification of estrogen binding to the receptor. To assess the effectiveness of the method for detecting environmental estrogenic chemicals, we chose two classes of xenoestrogens: bisphenol A, a synthetic xenoestrogen, and genistein, a phytoestrogen. This system is highly sensitive and amenable to use in the field, providing an efficient and economic tool for measuring minuscule amounts of endocrine-disrupting chemicals in environmental or human samples.     

Synthesis and luminescence of Eu3+ doped nanocrystalline TiO2 spheres

Eu~(3+) doped TiO_2 anatase spheres were obtained by modified sol-gel approach.Spheres(110—250 nm) are composed of smaller(5-15 nm) nanocrystals and exhibit red emission under UV light excitation.Materials were synthesized by multi-step method from glycolated titania alkoxides.Europium doped(1.0 mol%) and non-doped spheres were synthesized.Their optical and structural properties were compared by materials characterization methods,such as X-ray powder diffraction,transmission electron microscopy and PL spectroscopy.Doped TiO_2 spheres are crystalline phase pure and exhibit high luminescence intensity.     

A 270-kb/s 35-mW modulator IC for GSM cellular radio hand-heldterminals

The modulator IC is a mixed analog/digital transceiver component in a chip set that is designed for the hand-held terminals of the pan-European 900-MHz Groupe Special Mobile (GSM) digital cellular radio network. The concept of the radio-frequency environment in which the circuit is used is explained, focusing on the differences in existing systems. The architecture and different functions of the modulator circuit and details of the digital and analog processing in the transmission mode are discussed. The receiving mode, which is mostly based on analog processing, is highlighted. The device generates Gaussian minimum-shift-keying (GMSK) modulation and converts the received signal to 8-b words after filtering. The modulator IC uses digital waveform generation and a quadrature signal representation. This device is implemented in a 1.5-μm CMOS technology. The power consumption is less than 35 mW from a 5-V supply     

Enhanced lateral current transport via the front N+ diffused layer of n‐type high‐efficiency back‐junction back‐contact silicon solar cells

N‐type back‐contact back‐junction solar cells were processed with the use of industrially relevant structuring technologies such as screen‐printing and laser processing. Application of the low‐cost structuring technologies in the processing of the high‐efficiency back‐contact back‐junction silicon solar cells results in a drastic increase of the pitch on the rear cell side. The pitch in the range of millimetres leads to a significant increase of the lateral base resistance. The application of a phosphorus doped front surface field (FSF) significantly reduces the lateral base resistance losses. This additional function of the phosphorus doped FSF in reducing the lateral resistance losses was investigated experimentally and by two‐dimensional device simulations. Enhanced lateral majority carrier's current transport in the front n⁺ diffused layer is a function of the pitch and the base resistivity. Experimental data show that the application of a FSF reduces the total series resistance of the measured cells with 3.5 mm pitch by 0.1 Ω cm² for the 1 Ω cm base resistivity and 1.3 Ω cm² for the 8 Ω cm base resistivity. Two‐dimensional simulations of the electron current transport show that the electron current density in the front n⁺ diffused layer is around two orders of magnitude higher than in the base of the solar cell. The best efficiency of 21.3% was obtained for the solar cell with a 1 Ω cm specific base resistivity and a front surface field with sheet resistance of 148 Ω/sq. Copyright © 2008 John Wiley & Sons, Ltd.     

Experiment on cross relaxation in CO2

The details of the hole-burning process are studied experimentally and theoretically in a Doppler-broadened gain or absorption line in pure CO2and in CO2-N2mixtures contained in a test cell. The change of absorption or gain of the test cell when irradiated by a saturating laser in aPtransition is probed with another laser operating in one of manyRtransitions. In this way one may determine the rate of velocity cross relaxation within a single rotational-vibrational level and the rate of cross relaxation between different rotational levels of the upper and lower vibrational states. When the probing laser shares a common upper or lower level with the saturating laser, a pip is observed in the differential absorption or gain profile at total pressures of less than 0.5 torr. At higher pressures the relaxation across the velocity profile eliminates the pip. An analysis is presented of the population distribution in the multilevel system of CO2. Three of the relaxation rates (describing the relaxation across the velocity profile of a single level, the relaxation among rotational levels of the vibrational state, and the phenomenological relaxation rate of entry into and departure from the upper and lower vibrational states) are determined. The last of the three rates is found to be dominated by diffusion at the pressures used in the experiment.     

Fracturing dams,fractured data: Empirical trends and characteristics of existing and removed dams in the United States

Dam removals in the United States continue to accelerate in pace and scope, but no national analyses have examined how removed dams compare with existing dam stock. Here, we review and analyse the best available national data on dams from the National Inventory of Dams (NID), dam removals from American Rivers, the U.S. Geological Survey, and the National River Restoration Science Synthesis databases to compare trends and characteristics of removed versus existing dams in the United States. If historical trends continue, by 2050 the United States can expect between 4,000 and 36,000 total removals, including 2,000–10,000 removals of NID dams. Best‐fit regression models estimate total costs between $50.5 million and $25.1 billion (mean $10.5 billion, median $416.5 million) for all removals and $29.6 million to $18.9 billion (mean $7.2 billion, median $285 million) for NID removals, a significant cost savings over present stated dam rehabilitation needs. Structural characteristics and ages of documented removals are not representative of existing dams, with privately owned hydroelectric dams subject to public oversight and water supply dams the most disproportionately removed. We conclude that dam removal science would benefit from the creation of an interdisciplinary framework for studying dams as environmental, social, and technological interventions, facilitated by transparent datasets around dams and removals and reflexive research approaches that combine statistical approaches with place‐based analyses.