The origin of photovoltaic responses in BiFeO3 multiferroic ceramics

Multiferroic BiFeO(3) (BFO) ceramics with electrodes of indium tin oxide (ITO) and Au thin films exhibit significant photovoltaic effects under near-ultraviolet illumination (λ = 405 nm) and show strong dependences on light wavelength, illumination intensity, and sample thickness. The correlation between photovoltaic responses and illumination intensity can be attributed to photo-excited and thermally generated charge carriers in the interface depletion region between BFO ceramic and ITO thin film. A theoretical model is developed to describe the open-circuit photovoltage and short-circuit photocurrent density as a function of illumination intensity. This model can be applied to the photovoltaic effects in p-n junction type BFO thin films and other systems. The BFO ceramic exhibits stronger photovoltaic responses than the ferroelectric Pb(1-x)La(x)(Zr(y)Ti(1-y))(1-x/4)O(3) (PLZT) ceramics under near-ultraviolet illumination. Comparisons are made with other systems and models for the photovoltaic effect.

Temperature-dependent structures of proton-conducting Ba(Zr(0.8-x)Ce(x)Y(0.2))O(2.9) ceramics by Raman scattering and x-ray diffraction

In situ temperature-dependent micro-Raman scattering and x-ray diffraction have been performed to study atomic vibration, lattice parameter and structural transition of proton-conducting Ba(Zr(0.8-x)Ce(x)Y(0.2))O(2.9) (BZCY) ceramics (x = 0.0-0.8) synthesized by the glycine-nitrate combustion process. The Raman vibrations have been identified and their frequencies increase with decreasing x as the heavier Ce(4+) ions are replaced by Zr(4+) ions. The main Raman vibrations of Ba(Ce(0.8)Y (0.2))O(2.9) appear near 305, 332, 352, 440 and 635 cm(-1). The X-O ( X=Ce, Zr, Y) stretching modes are sensitive to the variation of Ce/Zr ratio. A rhombohedral-cubic structural transition was observed for x = 0.5-0.8, in which the transition shifts toward higher temperature as cerium increases, except for Ba(Ce(0.8)Y(0.2))O(2.9). A minor monoclinic phase possibly coexists in the rhombohedral matrix for x = 0.5-0.8. The lower-cerium BZCYs (x = 0.0-0.4) ceramics do not exhibit any transition in the region of 20-900 °C, indicating a cubic phase at and above room temperature.

Evidence for a quasi-two-dimensional proton glass state in Cs5H3(SO4)(4); xH(2)O Crystals

We describe damping of hypersonic and ultrasonic longitudinal acoustic (LA) phonons in crystals of Cs 5H (3)(SO (4))(4);xH 2O (PCHS) between 100 and 360 K. The damping of LA phonons exhibits strong dispersion caused by relaxation processes in the region of transformation into the glasslike phase (T(g) approximately 260 K). Near T(g) the damping of ultrasonic phonons propagating in the basal plane reflects the cooperative freezing of acid protons. The damping of LA phonons propagating perpendicular to the basal plane can be fit by the Debye model and is due to the interaction between protons and LA phonons. This suggests that the proton glass state that is realized at T<T(g) has a quasi-two-dimensional nature.

Selection of recipients for donor organs in transplant medicine

This paper deals with a problem which has received a great deal of attention in the ethical literature, but about which very little is known empirically: the selection of recipients for organs in transplant medicine. Based on a larger study, it is shown how this problem is practically resolved in one European country, Germany. It is demonstrated that most of the criteria used to determine recipients are non-medical in nature, even though they generally tend to be rationalized in medical terms. Moreover, the choice of criteria depends as much on prognostic considerations as on personal indiosyncrasies and values held by individual physicians who are in charge at the various programs. Several examples of the extremely diverse policies in which this results are presented.

[The artery of the thumb metacarpophalangeal joint]

As a rule, a small artery passing through the palmar plate runs into the thumb metacarpophalangeal joint. Frequently, the joint vessel arises from the arteria princeps pollicis, and rarely from the arteria metacarpalis dorsalis I or from muscle branches of the arteria princeps pollicis. In 30% of our specimens we could find a third larger palmar thumb artery. To our knowledge, this vessel was not described up to now precisely. Frequently arising from the arteria princeps pollicis, it passes the whole region of the metacarpophalangeal joint of the thumb. Distally, the artery runs within the floor of the flexor pollicis longus tendon sheath. After a mean distance of 19.7 mm, the vessel passes through the wall of the tendon sheath between the A 1-pulley and the oblique pulley. This vessel anastomoses with the arteria radiopalmaris pollicis proximal to the junction of the digitopalmar arch. According to the nomenclature of anatomic variations in the forearm, we suggest to name the additional thumb vessel "Arteria mediana pollicis".

Hydrostatic optical cell with simple window structure for low temperature and hydrostatic pressure up to 5 kilobars

A compact gas high-pressure cell with four windows for optical studies of phase transitions at low temperature and hydrostatic pressure up to 5 kilobars has been made. Techniques for sealing window components are discussed.