Phonon and magnetoelastic coupling in Al0.5Ga0.5FeO3: Raman, magnetization and neutron diffraction studies.

The intriguing coupling phenomena among spin, phonon, and charge degrees of freedom in materials having magnetic, ferroelectric and/or ferroelastic order have been of research interest for the fundamental understanding and technological relevance. We report a detailed study on structure and phonons of Al0.5Ga0.5FeO3 (ALGF), a lead-free magnetoelectric material, carried out using variable temperature dependent powder neutron diffraction and Raman spectroscopy. Neutron diffraction studies suggest that Al3+ ions are distributed in one tetrahedrally (BO4) and three octahedrally (BO6) coordinated sites of the orthorhombic (Pc21n) structure and there is no structural transition in the temperature range of 7-800 K. Temperature dependent field-cooled and zero-field-cooled magnetization studies indicate ferrimagnetic ordering below 225 K (TN), and that is reflected in the low temperature powder neutron diffraction data. An antiferromagnetic type arrangement of Fe3+ ions with net magnetic moment of 0.13 µB/Fe3+ was observed from powder neutron diffraction analysis and it corroborates the findings from magnetization studies. At the magnetic transition temperature, no drastic change in lattice strain was observed, while significant changes in phonons were observed in the Raman spectra. The deviation of several mode frequencies from the standard anharmonicity model in the ferrimagnetic phase (below 240 K) is attributed to coupling effect between spin and phonon. Spin-phonon coupling effect is discernable from Raman bands located at 270, 425, 582, 695, 738, and 841 cm-1. Their coupling strengths (λ) have been estimated using our phonon spectra and magnetization results. BOn (n = 4, 6) libration (restricted rotation) mode at 270 cm-1 has the largest coupling constant (λ∼ 2.3), while the stretching vibrations located at 695 and 738 cm-1 have the lowest coupling constant (λ∼ 0.5). In addition to the libration mode, several internal stretching and bending modes of polyhedral units are strongly affected by spin ordering.

Elastic and anelastic relaxation behaviour of perovskite multiferroics II: PbZr0.53Ti0.47O3 (PZT)-PbFe0.5Ta0.5O3 (PFT).

Elastic and anelastic properties of ceramic samples of multiferroic perovskites with nominal compositions across the binary join PbZr0.53Ti0.47O3-PbFe0.5Ta0.5O3 (PZT-PFT) have been assembled to create a binary phase diagram and to address the role of strain relaxation associated with their phase transitions. Structural relationships are similar to those observed previously for PbZr0.53Ti0.47O3-PbFe0.5Nb0.5O3 (PZT-PFN), but the magnitude of the tetragonal shear strain associated with the ferroelectric order parameter appears to be much smaller. This leads to relaxor character for the development of ferroelectric properties in the end member PbFe0.5Ta0.5O3. As for PZT-PFN, there appear to be two discrete instabilities rather than simply a reorientation of the electric dipole in the transition sequence cubic-tetragonal-monoclinic, and the second transition has characteristics typical of an improper ferroelastic. At intermediate compositions, the ferroelastic microstructure has strain heterogeneities on a mesoscopic length scale and, probably, also on a microscopic scale. This results in a wide anelastic freezing interval for strain-related defects rather than the freezing of discrete twin walls that would occur in a conventional ferroelastic material. In PFT, however, the acoustic loss behaviour more nearly resembles that due to freezing of conventional ferroelastic twin walls. Precursor softening of the shear modulus in both PFT and PFN does not fit with a Vogel-Fulcher description, but in PFT there is a temperature interval where the softening conforms to a power law suggestive of the role of fluctuations of the order parameter with dispersion along one branch of the Brillouin zone. Magnetic ordering appears to be coupled only weakly with a volume strain and not with shear strain but, as with multiferroic PZT-PFN perovskites, takes place within crystals which have significant strain heterogeneities on different length scales.

Elastic and magnetoelastic relaxation behaviour of multiferroic (ferromagnetic + ferroelectric + ferroelastic) Pb(Fe0.5Nb0.5)O3 perovskite.

Resonant Ultrasound Spectroscopy has been used to characterize elastic and anelastic anomalies in a polycrystalline sample of multiferroic Pb(Fe(0.5)Nb(0.5))O(3) (PFN). Elastic softening begins at ~550 K, which is close to the Burns temperature marking the development of dynamical polar nanoregions. A small increase in acoustic loss at ~425 K coincides with the value of T(*) reported for polar nanoregions starting to acquire a static or quasi-static component. Softening of the shear modulus by ~30-35% through ~395-320 K, together with a peak in acoustic loss, is due to classical strain/order parameter coupling through the cubic → tetragonal → monoclinic transition sequence of ferroelectric/ferroelastic transitions. A plateau of high acoustic loss below ~320 K is due to the mobility under stress of a ferroelastic microstructure but, instead of the typical effects of freezing of twin wall motion at some low temperature, there is a steady decrease in loss and increase in elastic stiffness below ~85 K. This is attributed to freezing of a succession of strain-coupled defects with a range of relaxation times and is consistent with a report in the literature that PFN develops a tweed microstructure over a wide temperature interval. No overt anomaly was observed near the expected Néel point, ~145 K, consistent with weak/absent spin/lattice coupling but heat capacity measurements showed that the antiferromagnetic transition is actually smeared out or suppressed. Instead, the sample is weakly ferromagnetic up to ~560 K, though it has not been possible to exclude definitively the possibility that this could be due to some magnetic impurity. Overall, evidence from the RUS data is of a permeating influence of static and dynamic strain relaxation effects which are attributed to local strain heterogeneity on a mesoscopic length scale. These, in turn, must have a role in determining the magnetic properties and multiferroic character of PFN.

Postnatal developmental anatomy of testes and epididymis of Gaddi goats / Desarrollo anatómico postnatal de los testículos y epidídimo de cabras Gaddi

The study revealed that the testes of one-day-old Gaddi goats have descended in the scrotum along with adnexa. They were elongated compressed latero-medially and became ovoid during their postnatal growth and morphogenesis. The two testes were not different significantly in their weight and measurement. The average weight which was about 2.9 gm at birth grew to 107 gm (40X) in pubertal animals and nearly maintained it during the post-puberty (113 g). The mean length (1.46 cm), width (0.85 cm) and thickness (0.62 cm) also grew by 47, 60, and 83 times, respectively. In post-pubertal animals it measured 7.06 x 5.20 x 5.10 cm. The study indicated a very fast growth of the testes from birth to puberty, which did not alter significantly after that. A relatively much faster growth in thickness and width over the length was the reason behind the change of the morphology from more elongated shape at birth to ovoid shape on maturity. The mediastinum testis was grossly discernible in the testis even at birth. Epididymis was identifiable into caput, corpus and cauda. The gross linear mensuration of these components did not differ in the caput and cauda regions on either side, whereas the length of corpus was more on the left side in all age group of animals. The growth curve revealed a continuous growth of all segments, but the fastest growth occurred in the early postnatal life (at 12­18 month age).

El estudio reveló que los testículos de las cabras Gaddi, de un día de edad, descienden al escroto junto con sus anexos. Se elongaron en dirección latero-medial y convirtieron en ovoides durante su crecimiento postnatal y en la morfogénesis. Los dos testículos no fueron significativamente diferentes en su peso y medidas. El peso promedio fue aproximadamente de 2,9 g al nacer, y aumentó a 107 g (40X) en animales púberes y casi mantuvo su peso durante la post-pubertad (113 g). La longitud (1,46 cm), ancho (0,85 cm) y espesor (0,62 cm) también crecieron unas 47, 60 y 83 veces, respectivamente. En los animales post-puberales las medidas fueron de 7,06 x 5,20 x 5.10 cm. Se observó un crecimiento muy rápido de los testículos desde el nacimiento hasta la pubertad, sin alterarse de manera significativa posteriormente. Un crecimiento relativamente mucho más rápido en espesor y anchura, sobre la longitud, fue la razón detrás del cambio de la morfología desde la forma más alargada, presente en el nacimiento, a la forma ovoide de la madurez. El mediastino testicular fue claramente identificado en el testículo, inclusive en el nacimiento. En el epidídimo se identificaron las porciones de la cabeza, cuerpo y cola. La medición lineal de estos componentes no difirió en las regiones de la cabeza y cola de cada lado, mientras que la longitud del cuerpo fue mayor en el lado izquierdo en todos los grupos. La curva de crecimiento reveló un crecimiento continuo de todos los segmentos, pero el mayor crecimiento se produjo en la vida postnatal temprana (entre los 12 y 18 meses).

Tunneling electroresistance in multiferroic heterostructures.

We demonstrate the room temperature polar switching and tunneling in PbZr0.52Ti0.48O3 (PZT) ultra-thin films of thickness 3-7 nm, sandwiched between platinum metal and ferromagnetic La0.67Sr0.33MnO3 (LSMO) layers, which also shows magnetic field dependent tunnel current switching in Pt/PbZr0.52Ti0.48O3/La0.67Sr0.33MnO3 heterostructures. The epitaxial nature, surface quality and ferroelectric switching of heterostructured films were examined with the help of x-ray diffraction patterns, atomic force microscopy, and piezo force microscopy, respectively. The capacitance versus voltage graphs show butterfly loops above the coercive field (> ±3 V) of PZT for small probe area (∼16 µm(2)). The effect of ferroelectric switching was observed in current density versus voltage curves with a large variation in high-resistance/low-resistance (HRS/LRS) ratio (2:1 to 100:1), however, these effects were more prominent in the presence of in-plane external magnetic field. The conductance is fitted with Brinkman's model, and the parabolic conductance upon bias voltage implies electron tunneling governs the transport.

Postnatal development of testis in gaddi goat (capra hircus) / Desarrollo postnatal del testículo en la cabra gaddi (capra hircus)

A study was conducted on the testicles of 30 male Gaddi goats, divided into 3 groups viz; prepubertal (0 day to 18 months), pubertal (<18 months to >5 yrs) and post- pubertal (>5 yrs) ages. The study revealed that the testis was covered by fibroserous tunica albuginia having outer fibrous layer and inner vascular layer with smooth muscle fibers at birth. The tunica albuginia continuously grew in thickness from prepubertal to postpubertal animals. The septula testis arising from the tunica albuginia, divided the parenchyma in lobules and converged at mediastinum testis. Few differentiated and undifferentiated Leydig cells were present in the intertubular spaces of neonates, which enormously increased in pubertal animals and replaced by fibroblasts in the postpubertal animals. The parenchyma comprised of solid sex cords in new born kids. These were converted into luminated tubules after 6 months of age and had clear cut tubuli contorti and tubuli recti leading to the mediastinum testis. In "0" day old kids, sex cords were filled with undifferentiated small cells located peripherally along the basement membrane and large primordial germ cells located centrally. By six months of age, latter started showing sign of degeneration and thus luminization of tubules started. Spermatogenesis startedin the seminiferous tubules of 12-18 months goat. In pubertal animals all the stages of spermatogenic cells and Sertoli cells were identified in the seminiferous tubules. The population of gonia cells and primary + secondary spermatocytes were 35% and 30% respectively. In postpubertal animals gonia cells were reduced to <30% and Primary + secondary spermatocytes were <20%. Many degenerating seminiferous tubules showed hyalinization, fibrosis and giant cells. The stroma and parenchyma ratio which was 35:65 at birth became 30:60 at 6 months, 25:75 at 12 months and 15:85 in pubertal and 20:80 in postpubertal animals. Increased stroma in last phase was associated with replacement of seminiuferous tubules by fibrous elements.

Se realizó un estudio en 30 testículos de cabras Gaddi machos divididos en 3 grupos: prepúberes (0 días a 18 meses), púberes (<18 meses y >5 años) y post-púberes (>5 años). El estudio reveló que los testículos al nacimiento estaban cubiertos por una túnica albugínea fibroserosa con una capa fibrosa externa y otra capa vascular interna con fibras musculares lisas. En los animales prepúberes hasta los pospúberes, la túnica albugínea mostró un crecimiento continuo de espesor. El septo testicular derivado de la túnica albugínea, divide el parénquima en lóbulos convergentes en el mediastino testicular. En los espacios intertubulares de los testículos de los recién nacidos, se observaron escasas células interticiales diferenciadas e indiferenciadas, sin embargo, se registró un aumento importante en los animales púberes las cuales fueron reemplazadas por fibroblastos después de la pubertad. El parénquima en los testículos de los animales recién nacidos estaba compuesto por cordones sexuales continuos. Estos se convierten en túbulos luminados después de los 6 meses de edad, evidenciando túbulos contorneados y rectos que conducen al mediastino testicular. En animales de 0 días de edad, los cordones sexuales presentaban pequeñas células no diferenciadas y situadas periféricamente a lo largo de la membrana basal y grandes células germinales primordiales céntricas. A los seis meses de edad, este último comenzó a mostrar signos de degeneración. La espermatogénesis se inició en los túbulos seminíferos desde los 12 a 18 meses de edad. En los animales púberes se identificaron en los túbulos seminíferos todas las etapas de las células de espermatogénesis y células sustentaculares. La población de células gonia fue del 35% y de espermatocitos primarios más secundarios 30%. En los animales pospúberes las células gonia se redujeron a <30% y espermatocitos primarios más secundarios a < 20%. Muchos túbulos seminíferos presentaron degeneración. La relación parénquima/estroma fue 35:65 al nacer, luego de 30:60 a los 6 meses, de 25:75 a los 12 meses, de 15:85 en animales prepúberes y 20:80 en la pubertad. El aumento del estroma en la última fase fue asociado con el reemplazo de los túbulos seminíferos por elementos fibrosos.

Switching ferroelectric domain configurations using both electric and magnetic fields in Pb(Zr,Ti)O3-Pb(Fe,Ta)O3 single-crystal lamellae.

Thin single-crystal lamellae cut from Pb(Zr,Ti)O3-Pb(Fe,Ta)O3 ceramic samples have been integrated into simple coplanar capacitor devices. The influence of applied electric and magnetic fields on ferroelectric domain configurations has been mapped, using piezoresponse force microscopy. The extent to which magnetic fields alter the ferroelectric domains was found to be strongly history dependent: after switching had been induced by applying electric fields, the susceptibility of the domains to change under a magnetic field (the effective magnetoelectric coupling parameter) was large. Such large, magnetic field-induced changes resulted in a remanent domain state very similar to the remanent state induced by an electric field. Subsequent magnetic field reversal induced more modest ferroelectric switching.

Studies of the Room-Temperature Multiferroic Pb(Fe0.5Ta0.5)0.4(Zr0.53Ti0.47)0.6O3: Resonant Ultrasound Spectroscopy, Dielectric, and Magnetic Phenomena.

Recently, lead iron tantalate/lead zirconium titanate (PZTFT) was demonstrated to possess large, but unreliable, magnetoelectric coupling at room temperature. Such large coupling would be desirable for device applications but reproducibility would also be critical. To better understand the coupling, the properties of all 3 ferroic order parameters, elastic, electric, and magnetic, believed to be present in the material across a range of temperatures, are investigated. In high temperature elastic data, an anomaly is observed at the orthorhombic mm2 to tetragonal 4mm transition, Tot = 475 K, and a softening trend is observed as the temperature is increased toward 1300 K, where the material is known to become cubic. Thermal degradation makes it impossible to measure elastic behavior up to this temperature, however. In the low temperature region, there are elastic anomalies near ≈40 K and in the range 160-245 K. The former is interpreted as being due to a magnetic ordering transition and the latter is interpreted as a hysteretic regime of mixed rhombohedral and orthorhombic structures. Electrical and magnetic data collected below room temperature show anomalies at remarkably similar temperature ranges to the elastic data. These observations are used to suggest that the three order parameters in PZTFT are strongly coupled.

Dynamic nanocrystal response and high temperature growth of carbon nanotube-ferroelectric hybrid nanostructure.

A long standing problem related to the capping of carbon nanotubes (CNT) by inorganic materials at high temperature has been solved. In situ dynamic response of Pb(Zr0.52Ti0.48)O3 (PZT) nanocrystals attached to the wings of the outer surface of PZT/CNT hybrid-nanostructure has been demonstrated under a constant-energy high-resolution transmission electron microscopy (HRTEM) e-beam. PZT nanocrystals revealed that the crystal orientations, positions, faces, and hopping states change with time. HRTEM study has been performed to investigate the microstructure of hybrid nanostructures and nanosize polycrystal trapped across the wings. Raman spectroscopy was utilized to investigate the local structures, defects, crystal qualities and temperature dependent growth and degradation of hybrid nanostructures. Raman spectra indicate that MWCNT and PZT/MWCNT/n-Si possess good quality of CNT before and after PZT deposition until 650 °C. The monoclinic Cc/Cm phase of PZT which is optimum in piezoelectric properties was prominent in the hybrid structure and should be useful for device applications. An unusual hexagonal faceting oscillation of the nano-crystal perimeter on a 10-30 s period is also observed.

N-doped ZnO thin film for development of magnetic field sensor based on surface plasmon resonance.

Magnetic-field-dependent optical properties of nitrogen-doped ZnO (ZnO:N) thin films were investigated using surface plasmon resonance (SPR) and a highly sensitive (4.65/Tesla) magnetic field sensor has been realized. The refractive index (RI) of ZnO:N film increases from 1.949 to 2.025 with increase in N doping from 0% to 10% demonstrating tunable RI. In contrast to pure ZnO, SPR curves for ZnO:N films exhibit a shift toward lower angles with increasing applied magnetic field from 0 to 35 mT due to change in reflectance of light upon reflection from ferromagnetic surface. Results indicate promising application of ferromagnetic ZnO:N film as a magnetic field sensor.

Temperature tuned defect induced magnetism in reduced graphene oxide.

The existence of ferromagnetism in the wonder material graphene has opened up the path for many future spintronics and memory applications. But simultaneously it is very important to understand the variation of these properties with temperature in regards to the device applications. Here we observed defect induced ferromagnetism in chemically reduced graphene and the effect of temperature on it. Several theoretical studies have proved that the main cause of ferromagnetism in graphene is due to various defects. The observed results established that these defects can be mended by treating the samples at elevated temperatures but sacrificing the ferromagnetism simultaneously. Hence, temperature plays a crucial role in controlling the magnetism as well as the defects in graphene. In this study we revealed that at 600 °C the self-repair mechanism helps the defects to mend but resulting in the decrement of magnetization and providing a good quality graphene with less defects.

Magnetic switching of ferroelectric domains at room temperature in multiferroic PZTFT.

Single-phase magnetoelectric multiferroics are ferroelectric materials that display some form of magnetism. In addition, magnetic and ferroelectric order parameters are not independent of one another. Thus, the application of either an electric or magnetic field simultaneously alters both the electrical dipole configuration and the magnetic state of the material. The technological possibilities that could arise from magnetoelectric multiferroics are considerable and a range of functional devices has already been envisioned. Realising these devices, however, requires coupling effects to be significant and to occur at room temperature. Although such characteristics can be created in piezoelectric-magnetostrictive composites, to date they have only been weakly evident in single-phase multiferroics. Here in a newly discovered room temperature multiferroic, we demonstrate significant room temperature coupling by monitoring changes in ferroelectric domain patterns induced by magnetic fields. An order of magnitude estimate of the effective coupling coefficient suggests a value of ~1 × 10(-7) sm(-1).

Relaxor-ferroelectric superlattices: high energy density capacitors.

We report the breakdown electric field and energy density of laser ablated BaTiO(3)/Ba((1-x))Sr(x)TiO(3) (x = 0.7) (BT/BST) relaxor-ferroelectric superlattices (SLs) grown on (100) MgO single crystal substrates. The dielectric constant shows a frequency dispersion below the dielectric maximum temperature (T(m)) with a merger above T(m) behaving similarly to relaxors. It also follows the basic criteria of relaxor ferroelectrics such as low dielectric loss over wide temperature and frequency, and 50 K shift in T(m) with change in probe frequency; the loss peaks follow a similar trend to the dielectric constant except that they increase with increase in frequency (~40 kHz), and satisfy the nonlinear Vogel-Fulcher relation. Well-saturated ferroelectric hysteresis and 50-80% dielectric saturation are observed under high electric field (~1.65 MV cm(-1)). The superlattices demonstrate an 'in-built' field in as grown samples at low probe frequency (<1 kHz), whereas it becomes more symmetric and centered with increase in the probe frequency system (>1 kHz) which rules out the effect of any space charge and interfacial polarization. The P-E loops show around 12.24 J cm(-3) energy density within the experimental limit, but extrapolation of this data suggests that the potential energy density could reach 46 J cm(-3). The current density versus applied electric field indicates an exceptionally high breakdown field (5.8-6.0 MV cm(-1)) and low current density (~10-25 mA cm(-2)) near the breakdown voltage. The current-voltage characteristics reveal that the space charge limited conduction mechanism prevails at very high voltage.

Emerging memories: resistive switching mechanisms and current status.

The resistance switching behaviour of several materials has recently attracted considerable attention for its application in non-volatile memory (NVM) devices, popularly described as resistive random access memories (RRAMs). RRAM is a type of NVM that uses a material(s) that changes the resistance when a voltage is applied. Resistive switching phenomena have been observed in many oxides: (i) binary transition metal oxides (TMOs), e.g. TiO(2), Cr(2)O(3), FeO(x) and NiO; (ii) perovskite-type complex TMOs that are variously functional, paraelectric, ferroelectric, multiferroic and magnetic, e.g. (Ba,Sr)TiO(3), Pb(Zr(x) Ti(1-x))O(3), BiFeO(3) and Pr(x)Ca(1-x)MnO(3); (iii) large band gap high-k dielectrics, e.g. Al(2)O(3) and Gd(2)O(3); (iv) graphene oxides. In the non-oxide category, higher chalcogenides are front runners, e.g. In(2)Se(3) and In(2)Te(3). Hence, the number of materials showing this technologically interesting behaviour for information storage is enormous. Resistive switching in these materials can form the basis for the next generation of NVM, i.e. RRAM, when current semiconductor memory technology reaches its limit in terms of density. RRAMs may be the high-density and low-cost NVMs of the future. A review on this topic is of importance to focus concentration on the most promising materials to accelerate application into the semiconductor industry. This review is a small effort to realize the ambitious goal of RRAMs. Its basic focus is on resistive switching in various materials with particular emphasis on binary TMOs. It also addresses the current understanding of resistive switching behaviour. Moreover, a brief comparison between RRAMs and memristors is included. The review ends with the current status of RRAMs in terms of stability, scalability and switching speed, which are three important aspects of integration onto semiconductors.

Gross anatomical, histological and histochemical studies on the postnatal development of the prostate gland of Gaddi goat / Estudios anatómicos macroscópicos, histológicos e histoquímicos sobre el desarrollo postnatal de la glándula prostática de la cabra Gaddi

The study was conducted on the prostate gland of Gaddi goat from one day old to more than five years of age divided into three groups viz; prepubertal (1 day old to < 18 months of age), pubertal (18 months to < 5 yrs of age) and postpubertal (> 5 yrs of age). The prostate comprised of corpus prostatae, a band like structure close to the junction of vesicular gland with the urethra, and the pars disseminate which extended in urethra well from its origin to the point of duct of bulbourethral gland. Microscopically, the corpus prostatae comprised of two compact glandular masses lying one over the other, dorsally over the origin of pelvic urethra covered by a thick fibro-reticular capsule. The gland composed of end pieces (luminated and non-luminated acini) and ducts arranged in lobulated fashion. The thickness of inter and intralobular connective tissue decreased with increased age at the expense of the growth of paraenchyma. With age the luminated secretory end pieces increased, while the non-luminatedend pieces decreased in the lobules of the gland. Glandular parenchyma were rich in mucous components by 6 month age serous and mucous components became almost equal and at 12 month age majority of the secretory end pieces turned in to serous type. The excretory ducts which were lined by stratified cuboidal epithelium in one day old kids changed to transitional epithelium in late prepubertal and pubertal animals. The glandular elements were PAS and Best's carmine reactive while interstitial connective tissue was non reactive. Mild alkaline phosphatase reaction was evident in the interstitial connective tissue cells. A strong acid phosphatase reaction was evident in the endothelium. BPB reaction for protein was moderate to intense. Ducts and acini were PAS and Alcian Blue reactive. The reaction for glycogen and AMPS contents in the gland increased with age. It was very intense in the pubertal animals. Moderate DNA activity, mild to moderate alkaline and acid...

Se realizó un estudio de la glándula próstatica de la cabra Gaddi, desde el día uno de nacimiento hasta después de los cinco años de edad, divididos grupos prepuberal (1 día a 18 meses de edad), puberal (18 meses a <5 años de edad) y post-púberes (más de 5 años de edad). La próstata estaba constituida por un cuerpo prostático, estructura como una banda cercana a la unión de la glándula vesicular con la uretra, y una pars diseminada la cual se extendía en las paredes de la uretra desde su origen hasta el punto de los conductos de la glándula bulbouretral. Microscópicamente, el cuerpo prostático está compuesto por dos masas compactas glandulares situadas una sobre la otra, dorsalmente sobre el origen de la uretra pélvica cubierta por una gruesa cápsula fibro-reticular. La glándula compuesta por piezas terminales (acinos luminal y no luminal) y conductos dispuestos en forma lobulada. El espesor del tejido conectivo inter e intralobulillar disminuyó con el aumento de la edad a expensas del crecimiento del parénquima. Con la edad aumentaron las piezas terminales secretoras luminales, mientras que en las piezas terminales no luminales, disminuyeron en los lóbulos de la glándula. El parénquima glandular era abundante en componentes mucosos a la edad de 6 meses, mientras que los componentes serosos y mucosas se equilibraron a los 12 meses de edad; la mayoría de las piezas finales secretoras se transformaron a tipo serosa. Los conductos excretores que estaban revestidos por epitelio cúbico estratificado en el día uno de las crías, cambió a epitelio de transición en los animales prepúberes y púberes. Los elementos glandulares fueron reactivos al PAS y al carmín de Best, mientras que el tejido conectivo intersticial no fue reactivo. Una reacción leve a la fosfatasa alcalina fue evidente en las células del tejido conectivo intersticial, mientras que una reacción fuerte se evidenció en el endotelio. La reacción de BPB para proteína fue de moderada a intensa. Los conductos...

Electric control of magnon frequencies and magnetic moment of bismuth ferrite thin films at room temperature.

Here, we report the tuning of room-temperature magnon frequencies from 473 GHz to 402 GHz (14%) and magnetic moment from 4 to 18 emu∕cm(3) at 100 Oe under the application of external electric fields (E) across interdigital electrodes in BiFeO(3) (BFO) thin films. A decrease in magnon frequencies and increase in phonon frequencies were observed with Magnon and phonon Raman intensities are asymmetric with polarity, decreasing with positive E (+E) and increasing with negative E (-E) where polarity is with respect to in-plane polarization P. The magnetoelectric coupling (α) is proved to be linear and a rather isotropic α = 8.5 × 10(-12) sm(-1).

Age Related Structural Changes in the Bulbourethral Gland of Gaddi Goat (Capra hircus) / Cambios Estructurales Relacionados con la Edad en la Glándula Bulbouretral de la Cabra Gaddi (Capra hircus)

A study was conducted on the bulbourethral glands of 30 Gaddi goats, divided into three groups of 10 animals in each viz; Prepubertal (1 day old to < 18 months of age), Pubertal (18 months to < 5yrs of age) and Postpubertal (>5yrs of age). The study revealed that the glands grew at a faster speed up-to 6 months of postnatal life after which the pace slowed down considerably. Almost 10 times increase in weight and more than three times increase in all the linear mensurations were observed in prepubertal group from the time of birth. The stroma vs parenchyma ratio which was 80:20 in one-day-old kids showed three times increase in parenchyma in prepubertal animals, and the ratio became 43:57. In one day old kids luminated and non-luminated secretory end pieces were arranged in small groups around widely luminated duct; the forerunner of the central cistern. Initially the gland contained serous as well mucous end pieces; the latter being more preponderant. But in pubertal animals it became a mucous type gland, with only a little numbers of serous end pieces. Histochemically, the glandular acini were reactive to PAS and Alcian blue indicated the presence of glycol-muco-complex in the secretory components of gland.

Se realizó un estudio sobre las glándulas bulbouretrales de 30 cabras Gaddi, divididas en tres grupos de 10 animales cada uno; prepúberes (desde 1 día de edad hasta <18 meses), púberes (desde 18 meses hasta <5 años de edad) y postpuberales (>5 años de edad). El estudio reveló que las glándulas crecen a una mayor velocidad hasta los 6 meses de vida postnatal, después de lo cual el ritmo baja considerablemente. En el grupo prepuberal se observó un aumento casi 10 veces en peso y más de tres veces en todas las mediciones lineales. La relación estroma v/s parénquima fue de 80:20 el primer día postnacimiento, mostrando un aumento de tres veces en el parénquima en los animales prepúberes, llegando a una proporción 43:57. En una de las cabras de un día de edad las piezas terminales secretoras luminal y no-luminal se organizaron en pequeños grupos alrededor del conducto luminal; el precursor de la cisterna central. Inicialmente la glándula contenía piezas terminales serosas y mucosas. Esta última tenía una mayor preponderancia. Sin embargo, en animales puberales se convirtió en una glándula de tipo mucosa, con sólo un pequeño número de piezas terminales serosas. Histoquímicamente, los acinos glandulares reactivos al PAS y azul Alcian indicaron la presencia de glicol-muco-complejos en los componentes de secreción de la glándula.

Magnetic control of ferroelectric interfaces.

We report the strong magnetic field dependence of ferroelectric PbZr(0.52)Ti(0.48)O(3) (PZT) films on half-metallic oxide La(0.67)Sr(0.33)MnO(3) (LSMO) electrodes. As the field H is increased, the hysteresis loop first broadens (becomes lossy) and then disappears at approximately H = 0.34 T and ambient temperatures. The data are compared with the theories of Pirc et al (2009 Phys. Rev. B 79 214114), Parish and Littlewood (2008 Phys. Rev. Lett. 101 166602) and Catalan (2006 Appl. Phys. Lett. 88 102902). The results are interpreted as due not to magnetocapacitance but to the sharp negative magnetoresistance in LSMO at low magnetic fields (Hwang et al 1996 Phys. Rev. Lett. 77 2041), which causes a dramatic increase in leakage current through the PZT.

New cryogenic phase transitions in SrSnO3.

Strontium stannate is under study as an ultra-stable dielectric material for microelectronic applications at low temperatures. It is known to have a remarkably temperature-independent dielectric constant from 27 K to room temperature. However, we report anomalies in the Raman spectra, dielectric response, and differential thermal analysis of strontium stannate compatible with a structural phase transition at 160 K. Further anomalies are seen in calorimetric and Raman data (but not dielectric data) that suggest another phase transition at 270 K. A preliminary x-ray powder diffraction study confirms a small change in the pseudo-cubic lattice constant a(T) at the lower transition.

Gerentological studies on the gross and histomorphology of the vesicular gland of gaddi goat (Copra hircus) / Estudios gerontológicos en anatomía e histomorfología de la glándula vesicular de cabra gaddi (Cabra hircus)

The study was conducted on the vesicular glands of 30 entire pure male Gaddi goats from birth to 5yrs and 6 months of age, divided into three equal size groups of 10 animals in each viz; Pre-pubertal (lday old to <18 months of age), Pubertal (18 months to < 5years of age) and Post-pubertal (>5 years) age groups. In new born kid the glands were small, white cord like. It became "?" shaped at 6 months and "S" shaped at 12 months of age. A significant growth in size and weight of gland occurred at 6 month, then up to 12 month and beyond it grew slowly. The secretory acini of the lobules were lined by pseudostratified ciliated columnar epithelium which contained A-tall columnar, B-basal and C-narrow columnar type of cells. The number per unit area and size of the gland increased with age significantly from birth in the prepubertal animals and up to puberty. In post-pubertal animals it did not grow significantly, rather the connective tissue elements were increased in the capsule (adventitia). The intralobular connective tissue however, decreased at the expense of growth of acini at all ages.

Se realizó un estudio de las glándulas vesiculares de 30 cabras Gaddi, macho, totalmente puras desde el nacimiento hasta los 5 años y 6 meses de edad, divididas en tres grupos de 10 animales cada uno, pre-puberal (día 1 de edad a <18 meses de edad), pubertad (18 meses a <5 años de edad) y post-puberal (> 5 años). En el recién nacido las glándulas eran pequeñas, como un cordón blanco. Se presentó en forma de "?" a los 6 meses y de "S" a los 12 meses de edad. Un importante crecimiento en tamaño y peso de la glándula se produjo a los 6 meses, luego de 12 meses y más, creció lentamente. Los acinos secretores de los lóbulos se alinearon como epitelio columnar ciliado pseudoestratificado, los cuales contienen células de tipo A-columnar alto, B-basal y C-columnar estrecho. El número por unidad de área y el tamaño de la glándula aumentó significativamente con la edad desde su nacimiento en los animales prepuberes y hasta la pubertad. En animales post-puberales no creció significativamente, y los elementos del tejido conectivo se incrementaron en la cápsula (adventicia). Sin embargo, el tejido conectivo intralobular, disminuyó a expensas del crecimiento de los acinos, en todas las edades.