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Here, we report the successful synthesis of a spin- and charge-decoupled diluted magnetic semiconductor (DMS) (Ca,Na)(Zn,Mn)2As2, crystallizing into the hexagonal CaAl2Si2 structure. The compound shows a ferromagnetic transition with a Curie temperature up to 33K with 10% Na doping, which gives rise to carrier density of np∼1020cm-3. The new DMS is a soft magnetic material with HC<400 Oe. The anomalous Hall effect is observed below the ferromagnetic ordering temperature. With increasing Mn doping, ferromagnetic order is accompanied by an interaction between the local spin and mobile charge, giving rise to a minimum in resistivity at low temperatures and localizing the conduction electrons. The system provides an ideal platform for studying the interaction of the local spins and conduction electrons. [ABSTRACT FROM AUTHOR]

We investigate the barrier imperfection and interfacial scattering effects on resistance-area product (RA) and tunneling magnetoresistance (TMR) of magnesium oxide (MgO) based magnetic tunneling junction (MTJ). We assume that barrier imperfection reduces the band gap of MgO; thus, it affects both TMR and RA values. The lattice mismatch between MgO and magnetic electrodes leads to interface scattering which reduces TMR. As an application, the MTJ two-state resistance variations due to the process variations are also discussed in the paper. [ABSTRACT FROM AUTHOR]

The electronic paramagnetic resonance (EPR) parameters (g factor gi, and hyperfine structure constants Ai, with i = || and ⊥) and tetragonal distortion of the Cu2+ center in Al2O3 are unified interpreted from the perturbation formulas for a 3d9 ion in tetragonally elongated octahedral. In the calculations, the impurity Cu2+ is found to occupy the host trigonally-distorted octahedral Al3+ site with the tetragonal elongation distortion due to the Jahn–Teller effect, despite the original trigonal distortion of the host cation site. The contributions to EPR parameters from both the spin–orbit coupling of the central ion and that of the ligands are taken into account. The defect structure of the Cu2+ center (characterized by the relative tetragonal elongation ratio η ≈ 4.3% along the C4 axis) was determined from the calculation. Furthermore, the calculated results agree well with the experimental data and need fewer adjustable parameters than the previous studies. [ABSTRACT FROM AUTHOR]

Multichannel transition visible and near-infrared (NIR) fluorescences have been captured in Dy3+-doped fiber-adaptive Na2O-ZnO-PbO-GeO2-TeO2 glasses. The maximum stimulated emission cross-sections σem-max were derived to be 0.33 × 10-21, 3.66 × 10-21, and 0.67 × 10-21 cm2 for conventional visible emissions assigned to 4F9/2→6HJ (J = 15/2, 13/2, and 11/2) transitions, respectively. Infrequent multi-peak NIR emissions were recorded in the spectral range of 900-1500 nm, among which the values of σem-max were solved to be 1.05 × 10-22 and 1.56 × 10-22 cm2 for ∼1.02 and ∼1.18 μm emission bands. Internal quantum efficiency for the 4F9/2 level and external quantum yield for visible emissions of Dy3+ were determined to be 88.44% and 12.38%, severally. Effective multichannel radiative emissions reveal a potential in developing fiber-lighting sources, tunable lasers, and NIR optical amplifiers. [ABSTRACT FROM AUTHOR]

The optical band gap of ZnO thin films deposited on fused quartz by metal-organic chemical-vapor deposition was studied. The optical band gap of as-grown ZnO blueshifted from 3.13 to 4.06 eV as the growth temperature decreased from 500 to 200 °C. After annealing, the optical band gap shifted back to the single-crystal value. All the ZnO thin films studied show strong band-edge photoluminescence. X-ray diffraction measurements showed that samples deposited at low temperatures (<450 °C) consisted of amorphous and crystalline phases. The redshift of the optical band gap back to the original position after annealing was strong evidence that the blueshift was due to an amorphous phase. The unshifted photoluminescence spectra indicated that the luminescence was due to the crystalline phase of ZnO, which was in the form of nanocrystals embedded in the amorphous phase. [ABSTRACT FROM AUTHOR]

The characteristics of organic light-emitting devices based on tris-(8-hydroxyqunoline) aluminum with an ultrathin tetrahedral amorphous carbon (ta-C) film on indium tin oxide have been investigated. The device with a 1.0-nm ta-C layer has the highest current and power efficiency. The current efficiency of a device with a ta-C layer thickness of 1.0 nm is 3.7 cd/A at 20 mA/cm2, however, the current efficiency of a standard device without a ta-C layer is 2.56 cd/A at the same current density. The current efficiency is improved by 46% compared to the standard device. Although there is a 1.2-V increase in driving voltage for 100-cd/m2 luminance, the power efficiency is still improved by 22% compared to that of the standard device. The improvement of the efficiency is due to smoothing indium tin oxide surface, blocking hole injection from anode and balancing hole and electron currents. The optimal thickness of ta-C layer for hole injection mechanics can be understood by tunneling. [ABSTRACT FROM AUTHOR]

We study the electric field (EF)-assisted magnetization switching in perpendicular magnetic free layer guided by an Oersted field using micromagnetic simulations. The EF is used to reduce the perpendicular magnetic anisotropy (PMA), and thus change the easy axis from the perpendicular to the in-plane. The Oersted field is used to guide the magnetization to the desired switching directions. The effects of various physical parameters, such as the damping constant, the PMA change, the PMA after EF, the saturation magnetization, and the Oersted field, on the switching times are examined. The simulation results indicate that the switching time decreases with the increase in the damping constant and the Oersted field. The EF efficiency has a significant effect on the switching performance. In order to make a fast and energy-saving switching, the PMA of the free layer needs to be properly controlled. Simulation results also show that a material with higher Ms needs a lower EF efficiency for fast switching. For the merit of a fast switching, large damping constant ( $\alpha > 0.1$ ) should be used. In addition, large damping constant requires a small Oersted field for a reliable switching, which reduces the energy during writing. For $\alpha = 0.3$ , a fast total switching time within 3 ns can be achieved with an Oersted field as small as 1 mT. [ABSTRACT FROM AUTHOR]

In this paper, we develop a portable dynamic switching model for perpendicular magnetic tunnel junctions (MTJs) considering both thermal fluctuation and process variations. The model uses macro-spin approximations where the free layer (FL) of MTJ is assumed to be in a single-domain structure. The model can generate dynamic switching transience curves at different current densities and simulate the switching successful rates for the given pulse lengths at different current densities. We also use the model to study the impact of temperature and device process variations on the switching performance, such as switching time variations. It is shown that the temperature effect is not significant when the switching current is relatively larger, and hence the spin current effect is strong enough to overtake the temperature effect. As for the process variations, it is shown that the FL thickness has a more significant effect on the switching time than the size of the FL does. [ABSTRACT FROM AUTHOR]

Sm3+ doped germanotellurite glasses (NZPGT) with maximum phonon energy of 793cm−1 have been prepared and characterized. Judd-Ofelt parameters Ωt (t=2, 4, 6) have been calculated to be 3.52×10−20, 4.70×10−20 and 1.90×10−20cm2, respectively. Large value of Ω2 indicates a high asymmetry and covalent environment around Sm3+ in the glass system. The maximum stimulated emission cross-section of the dominant transition 4G5/2→6H9/2 peaking at 645.0nm was derived to be 10.00×10−22cm2, predicting that the red fluorescence emission can be efficiently extracted from the optical glasses. The internal quantum efficiency and external quantum yield of 0.4wt% Sm2O3 doped NZPGT glasses were deduced to be 82.5% and 6.0%, respectively. The results demonstrate that Sm3+ doped NZPGT glasses are a potential candidate for developing tunable visible lasers, compact light sources and solid-state display devices. [ABSTRACT FROM AUTHOR]

A new diluted ferromagnetic semiconductor (Sr,Na)(Zn,Mn)2As2 is reported, in which charge and spin doping are decoupled via Sr/Na and Zn/Mn substitutions, respectively, being distinguished from classic (Ga,Mn)As, where charge and spin doping are simultaneously integrated. Different from the recently reported ferromagnetic (Ba,K)(Zn,Mn)2As2, this material crystallizes into the hexagonal CaAl2Si2 type structure. Ferromagnetism with a Curie temperature up to 20 K has been observed from magnetization. The muon spin relaxation measurements suggest that the exchange interaction between Mn moments of this new system could be different from the earlier diluted magnetic semiconductors (DMS) systems. This system provides an important means for studying ferromagnetism in DMS. [ABSTRACT FROM AUTHOR]

The magnetoelectroelastic solution of a generalized screw dislocation interacting with a wedge-shaped magnetoelectroelastic bi-material interface is derived in this paper. The screw dislocation is assumed to be straight and infinitely long in the z-direction and suffers a finite discontinuity in the displacement, electric potential and magnetic potential across the slip plane. The explicit closed-form analytical solution for the generalized stress field is derived by means of the complex variable and conformal mapping methods. The generalized stress intensity factors of the wedge tip induced by the dislocation and the image force acting on the dislocation are formulated and calculated. The influence of the wedge angle and the different bi-material constant combinations on the image force is discussed. Numerical examples for three particular wedge angles are calculated and compared with other available results. [ABSTRACT FROM AUTHOR]

In this paper, we present analyses of the media response to the write field with the recorded bits each of which involves a small number of grains. Our focus is on the development of a model that can be used to generate speedily the recorded patterns on continuous granular media. A two-dimensional Fourier analysis method is then used to construct the recorded patterns corresponding to given bit stream of write signals for signal to noise ratio evaluation. [ABSTRACT FROM AUTHOR]

Rapamycin (RAPA) is an immunosuppressive drug that prevents and treats graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplant (HCT). One possible mechanism for its efficacy is induction of tolerance, through increased number or enhanced survival of regulatory T cells. In our experiments, B10.D2 BM and splenocytes were injected into lethally irradiated BALB/cJ recipients. The mice received i.p. injections of either RAPA or vehicle control on days 1–28. There was a significant survival advantage in RAPA-treated mice. Evaluation of the skin biopsies showed a dense cellular infiltrate in RAPA-treated mice. Further characterization of these cells revealed a higher percentage of regulatory T cells characterized by FoxP3-positive cells in high-dose RAPA-treated mice as compared with controls on day 30. This effect appears to be dose dependent. When peripheral blood analysis for FoxP3-positive cells was performed, there was no significant difference observed in the RAPA-treated mice as compared with control mice. These data show a novel mechanism of rapamycin in GVHD, accumulation of regulatory T cells in the GVHD target tissue: the skin. [ABSTRACT FROM AUTHOR]

A new design method for tri-band filters with improved band allocation is proposed. The design concept treats different band allocations with different methodologies. For the bands assigned to adjacent frequency regions, transmission zeros are introduced to split one of the single bands into two. For the bands that are assigned separately, different harmonic modes of stepped-impedance resonators are used to realize different passbands. Two design examples with different responses and band allocations are given, and were verified by experiments, as well as full wave simulation results. [ABSTRACT FROM AUTHOR]

Allogeneic stem cell transplantation (alloSCT), especially in the mismatched setting, carries a high risk of life-threatening GvHD because of activation of donor T cells by Ag present on host cells. Removal of mature donor T cells can prevent GvHD but leads to delayed immune reconstitution, and an increased incidence of opportunistic infections and disease relapse. These findings demonstrate the vital role of donor T cells in providing graft-versus-tumor (GvT) and anti-pathogen effects as well as facilitating immune reconstitution. It has been well documented that GvHD can be separated from GvT effects, making it possible potentially to eliminate GvHD while preserving the immunotherapeutic benefits of donor T cells. Over the past decade, major attempts have been made to reduce GvHD incidence without loss of GvT effect, especially in the haplo-identical setting. Novel techniques to deplete host-reactive donor T cells selectively have been explored. This review focuses on the use of the photodynamic cell purging (PDP) process and of sorting memory T cells for the selective elimination of alloreactivity. Minimizing the threat of GvHD while maximizing the beneficial GvT effect would broaden the scope and effectiveness of alloSCT. [ABSTRACT FROM AUTHOR]

1. The present study focused on the potential effects of antibiotics on intestinal digestion and integrity in broilers in terms of disaccharidase activity, electrophysiological properties and morphology. 2. One-day-old Arbour Acres birds were randomly allocated to one of four treatment groups for 42 days; control, colistin (20 mg/kg), tylosin (55 mg/kg) or chlortetracycline (CTC, 55 mg/kg) groups. Colistin and tylosin supplementation, but not CTC supplementation, caused an increase in body weight gain. 3. Colistin and tylosin elevated the activities of maltase and sucrase in the mucosa of the jejunum on d 42. Age caused a gradual decrease in the short-circuit current (Isc) and conductance (Gt) of the ileum, as a measure of permeability. The Isc and Gt of the ileum were higher in the colistin-supplemented broilers than in the control birds on d 42. Tylosin- and CTC-supplemented birds displayed Isc and Gt values similar to those of the control birds. 4. Colistin supplementation increased the villus area in the jejunum and thinned the muscularis mucosae in the ileum compared with the control group. Tylosin supplementation decreased the thickness of the muscularis mucosae and the depth of crypt in the jejunum. CTC thickened the muscularis mucosae in the jejunum and ileum. 5. Colistin and tylosin exhibited a beneficial effect on intestinal digestion and integrity by enhancing disaccharidase activities and improving gut morphology and permeability. [ABSTRACT FROM AUTHOR]

Organic light-emitting devices with a mixture of tris-(8-hydroxyqunoline) aluminum (Alq3) and 4,4′-bis(carbazol-9-yl)-biphenyl (CBP) as the emitting layer have been fabricated. The devices were fabricated in the same run with a standard device without CBP for comparison, with an identical structure of indium tin oxide (ITO)/m-MTDATA (80 nm)/NPB (20 nm)/CBP:Alq3 (40 nm)/BCP (10 nm)/Alq3 (60 nm)/Mg:Ag (200 nm), where m-MTDATA is 4,4′,4″-tris(N-3-methylphenyl-N-phenyl-amino) triphenylamine, which is used to improve hole injection; NPB is N,N′-di(naphth-2-yl)-N,N′-diphenyl-benzidine; and BCP is 2,9-Dimethyl-4,7-diphenyl-1,110-phenanthorline. The ratio of CBP to Alq3 in mixture was varied from 0 to 2. For device with a ratio of 0.5, the current efficiency and power efficiency were significantly improved by 35% and 32%, respectively, compared to the standard device with Alq3 only as emitting layer. By increasing the ratio to 2, the current efficiency and power efficiency were dropped by 20% and 11%, respectively. The electroluminescence spectra showed a slight blueshift with the increase of CBP to Alq3 ratio. [ABSTRACT FROM AUTHOR]

A hole-blocking layer (HBL), 2,9-dimethyl-4, 7-diphenylphenanthroline (BCP), was incorporated between the hole-transporting layer (HTL) and hole-injection layer for a tris-(8-hydroxyqunoline) aluminum-based organic light-emitting device. Such a structure helps to reduce the hole-leakage to the cathode resulting in improved current efficiency. Optimum BCP thickness of around 3 nm was observed to produce a current efficiency of 3.25 cd/A, which corresponds to a 30% improvement compared to that of the standard device without BCP (2.5 cd/A). Low operating voltage was also achieved by minimizing the thickness of the HTL. Both operating voltage and efficiency can be tuned by varying the thickness of HTL and HBL, respectively. [ABSTRACT FROM AUTHOR]

A comparative study of in situ postgrowth annealing of organic layers before metal cathode was conducted on tris-(8-hydroxyqunoline) aluminum (Alq3)-based organic light-emitting devices (OLEDs). The devices were fabricated in the same run with a standard device without annealing for comparison, with an identical structure of indium tin oxide (ITO)/copper phthalocyanine (CuPc) (10 nm)/N,N′-di(naphthalene-l-yl)-N,N′-diphenyl-benzidine (NPB) (90 nm)/Alq3 (90 nm)/Mg:Ag (200 nm)/Ag (20 nm). The annealing temperature used was 60, 80, and 100 °C, respectively. It was found that, in situ postgrowth annealing improves the device performance, and annealing near the glass transition temperature of NPB (99.7 °C), improves device performance drastically. Power efficiency and current efficiency increase significantly with the annealing temperature, except the current efficiency for device annealed at 100 °C is slightly lower than that of the standard device. The voltage and current density for 100 cd/m2 luminance are 5.6 V and 4.4 mA/cm2, respectively, for the device annealed at 100 °C, in comparison to 9.2 V and 4.3 mA/cm2, respectively, for the standard device, the power efficiency is much improved by more than 40%. The in situ postgrowth annealed organic layers were characterized by photoluminescence and Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Poly(p-phenylene vinylene)-based polymer light-emitting devices using different thicknesses of tetrahedral amorphous carbon ultrathin films between indium tin oxide and polyethylenedioxythiophene hole transporting layer have been fabricated. The device with a 0.5 nm tetrahedral amorphous carbon (ta-C) layer has the highest luminance and current efficiency compared to that of other devices. The current efficiency of a standard device without a ta-C layer is 1.1 cd/A at 5 V, however, the current efficiency of a device with a ta-C layer thickness of 0.5 nm is 2.7 cd/A; the current efficiency is improved about 2.5 times compared to the standard device. The improvement of the efficiency is due to blocking the hole injection from anode and balancing the hole and electron current. The lifetime of a device with a ta-C layer is significantly much longer than the standard device, and the device with a 0.5 nm ta-C layer has the longest lifetime. [ABSTRACT FROM AUTHOR]

An efficient method for achieving ultra-broadband near-infrared signal amplification is proposed employing potential Pr3+ doped UV-sensitive germanium tellurite (NZPGT) glass fiber. The corresponding 1D2 → 1G4 transition emission covers from 1280 to 1680 nm with a full-width at half-maximum of 140 nm, and the associated emission cross-sections at 1390 and 1485 nm are derived to be 2.62 × 10-21 and 7.41 × 10-21 cm2, respectively. Large emission cross-section profile of Pr3+ in NZPGT glasses reveals that effective broadband amplification, especially at E- and S-band, is reasonable to be expected. Practicable operating mechanism of potential Pr3+ doped NZPGT glass fiber offers favorable prospects for rare-earth ion single-doped ultra-broadband signal amplifier. [ABSTRACT FROM AUTHOR]

A series of tris-(8-hydroxyquinoline) metal chelates with central metal ions of Al[sub 3+], Ga[sup 3+], and In[sup 3+] was synthesized, characterized, and used in organic electroluminescent devices. The ionization potential and optical band gap of the three chelates were measured by ultraviolet photoelectron spectroscopy and ultraviolet-visible spectrum, respectively. Two types of devices, with configurations of indium tin oxide (ITO)/N,N'-diphenyl-N,N'-(3-methylphenyl)-1,1'-biphenyl4,4'-diamine (TPD) (80 nm)/Mq[sub 3] (80 nm)/Mg:Ag (200 nm) and ITO/TPD (60 nm)/TPD:rubrene (3%) (20 nm)/Mq[sub 3] (80 nm)/Mg:Ag (200 nm) (M = Al, Ga, or In), were fabricated and characterized based on these metal chelates. In the first type of configuration, the metal chelates were used as both the emitter and the electron-transporting layer. In the second type of configuration, the metal chelates were believed to only act as electron-transporting layer. As the central ion changed, both the luminescence and the carrier transport properties of the metal chelates were changed. By comparing the performance of the two types of devices, we found that as the size of the metal ion increased, the luminance efficiency decreased and the electron mobility increased. [ABSTRACT FROM AUTHOR]

A model is introduced in this paper to describe the transition boundaries in perpendicular magnetic recording at extremely high density. In contrary to the previous signal generation models, effects of magnetization transition curvature and the track edge fluctuations are adequately included in the new model that is designed to capture the actual transition boundaries, i.e., the variations of magnetization distribution in both down-track and across-track directions. The model is used to predict the readback waveforms based on the detailed information obtained from micromagnetic simulations taking into account the head and media parameters. The model is therefore suitable for magnetic recording at extremely high densities when the impact of the transition curvature and the track edge effect on the recording performance becomes more significant. [ABSTRACT FROM AUTHOR]

Nanostructural zinc oxide fibers have been fabricated by a simple vapor transport method of heating the mixture of zinc oxide, gallium oxide, and carbon powders in air. The zinc oxide nanofibers showed cauliflower-like, disordered, vertically and horizontally aligned morphologies in different temperature regions. The aligned nanofibers were composed of hexagonal zinc oxide with good crystallinity. Gallium was doped into zinc oxide with a concentration of 0.73 at. %. The growth process and the characteristics can be interpreted by a vapor-liquid-solid mechanism. The field emission of the vertically aligned zinc oxide fiber array showed a low field emission threshold, high current density, rapid surge, and high field enhancement factor. The threshold electric field is about 2.4 V/μm at a current density of 0.1 μA/cm[sup -2]. The field enhancement factor was 2991. The emission current density and the electric field followed the Fowler–Nordheim relationship. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Applies the time-of-flight technique to determine electron drift mobility in films of tris(8-hydroxyquinolinolato) aluminum deposited at different rates on silicon. Increase in the drift mobility of electrons in tris(8-hydroxyquinolinolato) aluminum as the deposition rate decreases; Correlation between device efficiency and electron mobility.

Abstract: Efficient infrared emissions at ~ 1.2 and ~ 2.0 µm were recorded in Ho3+-single-doped and Ho3+/Yb3+-co-doped aluminum germanate glasses (NMAG), respectively. The maximum stimulated emission cross-sections for the ~ 1.2- and ~ 2.0 µm emissions were derived to be 2.3 × 10−21 and 5.8 × 10−21 cm2, respectively; then the gain cross-sections were further evaluated and the effective gains have been anticipated. In addition, the channel waveguide fabricated by K+-Na+ ion-exchanged method exhibited a complete single mode at 1.55 µm and the field diameters were identified to be horizontally 10.6 µm and vertically 6.7 µm. Effective amplified spontaneous emission at ~ 2.0 µm was recorded under 980 nm laser pumping. Broad bandwidth, large emission cross-section and perfect thermal ion-exchangeability indicate that Ho3+- and Yb3+-doped NMAG glasses are promising for the development of optical amplifier, tunable laser and light source operating at ~ 1.2 and ~ 2.0 µm.Graphical abstract: [ABSTRACT FROM AUTHOR]

Rare earth doped opaque aluminum tellurite ceramics exhibiting multicolor upconversion and color tunability have been synthesized and characterized. The multicolor fluorescence comprises of green, red, and blue upconversion emissions from Ho3+ and Tm3+ ions. By varying the intensity ratios between the upconversion emission bands, the fluorescence color can be tuned from multicolor to white color by changing the infrared wavelength pump power. The fluorescence color tunability in Ho3+/Tm3+/Yb3+ triply doped aluminum tellurite ceramics will lead to new applications in the field of multicolor fluorescence technology. [ABSTRACT FROM AUTHOR]

Rare-earth ion doped bismuthate (LZBB) glasses without traditional glass formers, lead and cadmium, have been attempted to prepare. In Er3+ doped LKBB glass system, Judd–Ofelt parameters Ω2, Ω4, and Ω6 have been derived to be 3.48×10-20, 9.47×10-21, and 1.01×10-20 cm2, respectively, which shows a medium symmetry of the ligand field in the site occupied by Er3+ and a less covalent environment of Er3+. Effective 1.53 μm fluorescence was recorded and the peak emission cross section is proved to be more than 9.0×10-21 cm2, which is much higher than those in phosphate, silicate, germanate, and tellurite glasses and beneficial to achieving powerful stimulated emission of Er3+ in LZBB glass system. Pr3+, Tm3+, and Ho3+ doped LZBB glasses with the maximum phonon energy of only ∼600 cm-1 are potential candidates for developing O-, S-, and U-band amplifiers and medical lasers. [ABSTRACT FROM AUTHOR]

The article comments on single-singlet and singlet-heat annihilations (SHA) in fluorescence-based organic light-emitting diodes under steady-state high current density (OLED). It was found out that the OLED performance was dependent on the substrate being used. It was also observed that a device with a good heat-release substrate, the roll-off efficiency was better. The author proposed an improved mathematical model explaining the SHA based on the original that was proposed Nakanotani et al.

Multichannel transition emissions in Pr3+-doped fluorotellurite (4BaF2–4AlF3–16BaO–6La2O3–70TeO2, BABLT) glasses have been quantitatively characterized. Broadband ∼1.48 µm near-infrared (NIR) emission due to 1D2 → 1G4 transition covering a 1.28–1.68 µm wavelength region possesses a full-width at half-maximum of 120 nm, along with the spontaneous emission probability (Aij) and maximum stimulated emission cross-section (σem) are calculated to be 693 s−1 and 8.97 × 10−21 cm2, respectively. Intense visible fluorescence originating from 3P0 and 1D2 levels has been observed and the radiant flux for the visible fluorescence of Pr3+ is solved to be 299 µW under commercial blue LED excitation. Quantitative characterization reveals that Pr3+-doped BABLT glasses exhibit a quantum yield (QY) as high as 14.9%, which is 3.1% higher than that in Pr3+-doped heavy metal germanium tellurite glasses. High QY and broadband ∼1.48 µm emission illustrate great advantages of Pr3+-doped BABLT glasses as fibre luminescence sources in photodynamic therapy treatment and gain media for tunable lasers and NIR optical amplifiers. [ABSTRACT FROM AUTHOR]

Traditionally, using a long post can cause progressive removal of the root structure, complicate the ability to re-treat the tooth if necessary and make it difficult to apply an adhesive bonding agent into the root canal. It is unclear if a shorter post length can be applied when a light translucent glass fibre post and adhesive resin cement are used. The aim of this study was to evaluate the biomechanical performance of endodontically treated teeth restored with three post materials, glass-fibre, stainless steel and cast-nickel chromium posts and cores of different lengths of 7, 10 and 13 mm. A 3D finite element analysis model of the maxillary central incisor was constructed. An occlusal load of 300 N was applied to a node at the palatal surface of the crown at 45° to the long axis of the tooth. von Mises stress analyses were carried out in three regions. Simulated data were collected for plotting various pattern graphics and conducting statistical tests. The pattern graphics showed that when the post length changed from 13 to 7 mm, the stress patterns were even and flat in all fibre-post groups, while the stress patterns of the metal-post groups showed an M-shaped peak and trough. Statistical tests showed that the shorter fibre post was superior to the longer metal post in some situations. Within the limitations of this study, it was concluded that when a metal post is used, the post should be as long as possible, while the biomechanical performance of a glass-fibre post combined with a composite resin core was less sensitive to post length. [ABSTRACT FROM AUTHOR]

A zinc oxide (ZnO) whisker network array with sixfold symmetry was fabricated on ZnO-buffered (0001) sapphire substrate by the vapour-phase transport method using a mixture of zinc oxide and graphite powders as source materials and patterned gold as catalyst. From the ZnO buffer layer, hexagonal ZnO nanorods with identical in-plane structure grew epitaxially along the [0001] orientation to form vertical stems. The branches grew horizontally from six side-surfaces of the vertical stem along [inline image] and other equivalent directions. Most whiskers were confined along the six preferential orientations and interconnected with each other to form a regular network structure. The growth mechanism is discussed. [ABSTRACT FROM AUTHOR]

The electro-elastic stress investigation on the interaction problem of a piezoelectric screw dislocation near a coated inclusion in a piezoelectric material has been carried out. In our study, three dissimilar material phases are involved: the matrix, the inclusion and the coating layer. All the three materials are piezoelectric and with different material constants. Explicit closed-form analytical solutions for the stress and electric displacement fields are obtained by using the complex variable method. The image force acting on the screw dislocation is calculated by using the generalized Peach-Koehler formula. Numerical examples for different material constant combinations are performed. The influences of material properties of the inclusion and the coating layer on the image forces are examined and discussed. [ABSTRACT FROM AUTHOR]

The problem of a Zener-Stroh crack initiated near a coated circular inclusion in a piezoelectric medium is investigated in this paper. By using the solution of a single piezoelectric screw dislocation near a coating inclusion as the Green's function, a Mode III displacement loaded crack is investigated. The proposed problem is formulated as a set of singular integral equations which are solved by numerical techniques. The influence of various parameters, such as the material constants of the inclusion, the coating, the matrix, the coating layer thickness, etc., on the crack behavior is studied. The stress and electric displacement intensity factors of the crack are derived. Several numerical examples are given and the results obtained are discussed in detail. [ABSTRACT FROM AUTHOR]

Postgrowth annealing was carried out on ZnO thin films grown by metal-organic chemical-vapor deposition. It was found from the scanning electron microscopy and atomic force microscopy measurements that the morphology of the thin films changed drastically after annealing. The as-grown thin films consist of fine nanoscale-sized sheets with random orientation. Upon annealing at 800 °C, the ZnO nanosheets changed to three-dimensional nanoneedles. The different types of the mass transport mechanisms are discussed and correlated with the experimental results. A coarsening kinetics developed by Lifshitz and Slyozov [J. Phys. Chem. Solids 19, 35 (1961)] and Wagner [Z. Elektrochem. 65, 581 (1961)] was used to estimate the activation energy of the coarsening process. The activation energy of the Ostwald ripening in ZnO films was estimated in the first attempt, and the value is at around 1.33 eV. Hall effect and photoluminescence measurements were carried out to investigate the effect of coarsening on electrical and optical properties of the ZnO thin films. [ABSTRACT FROM AUTHOR]

We aimed to understand the molecular-level changes occurring in the photosynthetic metabolic network in mutant chloroplasts. We performed comparative liquid chromatography-mass spectrometry protein profiling of wild-type (WT) and chlorophyll-deficient melon (Cucumis melo L.) mutants. We identified 390 differentially expressed proteins and 81 shared proteins varied significantly in abundance, of which 76 were upregulated and 5 were downregulated. Differentially expressed proteins were involved in the following biological processes: binding, catalytic, structural, transporter, and antioxidant activities. The mutant had 6.08-fold higher expression of glutamate-1-semialdehyde 2,1-aminomutase (GSAM), an enzyme that synthesizes the chlorophyll precursor, 5-aminolevulinic acid, and a 5.02-fold higher expression of pyridoxal biosynthesis protein, a GSAM coenzyme. An RNA recognition motif-containing protein (RRM) decreased in expression by 5.22-fold. This suggests that GSAM and RRM are particularly relevant to chlorophyll deficiency. [ABSTRACT FROM AUTHOR]

A blue organic light-emitting device with improved efficiency and excellent color purity is reported (Commission Internationale de’l Eclairage coordinates of x=0.1659 and y=0.0772 at 5 V), where N, N′-di(naphth-2-yl)-N, N′-diphenyl-benzidine (NPB), a traditional hole-transporting layer, was used as the emission layer. A significant increase in efficiency was achieved by confining the excitons within the NPB layer by two wide-band-gap hole-blocking layers sandwiching the NPB layer. This structure also increases the direct exciton formation at the NPB layer by promoting electrons to cross the NPB layer, responsible for further efficiency improvement. Optimized structure showed an external quantum efficiency of 1.38%, which accounts for a 25% increase compared to a standard device. [ABSTRACT FROM AUTHOR]

The electronic structure of the new diluted magnetic semiconductor Ba1-xKx(Zn1-yMny)2 As2 (x=0.30, y=0.15) in single crystal form has been investigated by angle-resolved photoemission spectroscopy (ARPES). Measurements with soft x rays clarify the host valence-band electronic structure primarily composed of the As 4p states. Two hole pockets around the G point, a hole corrugated cylinder surrounding the G and Z points, and an electron pocket around the Z point are observed, and explain the metallic transport of Ba1-xKx(Zn1-yMny)2 As2. This is contrasted with Ga1-xMnxAs (GaMnAs), where it is located above the As 4p valence-band maximum (VBM) and no Fermi surfaces have been clearly identified. Resonance soft x-ray ARPES measurements reveal a nondispersive (Kondo-resonance-like) Mn 3d impurity band near the Fermi level, as in the case of GaMnAs. However, the impurity band is located well below the VBM, unlike the impurity band in GaMnAs, which is located around and above the VBM. We conclude that, while the strong hybridization between the Mn 3d and the As 4p orbitals plays an important role in creating the impurity band and inducing high temperature ferromagnetism in both systems, the metallic transport may predominantly occur in the host valence band in Ba1-xKx (Zn1-yMny)2 As2 and in the impurity band in GaMnAs. [ABSTRACT FROM AUTHOR]

The electronic and magnetic properties of a new diluted magnetic semiconductor (DMS) Ba1-xKx(Zn1-yMny)2As2 , which is isostructural to so-called 122-type Fe-based superconductors, are investigated by x-ray absorption spectroscopy (XAS) and resonance photoemission spectroscopy (RPES). Mn L2.3-edge XAS indicates that the doped Mn atoms have a valence 2+ and strongly hybridize with the 4p orbitals of the tetrahedrally coordinating As ligands. The Mn 3d partial density of states obtained by RPES shows a peak around 4 eV and is relatively high between 0 and 2 eV below the Fermi level (EF) with little contribution at EF, similar to that of the archetypal DMS Ga1-xMnx As. This energy level creates a d5 electron configuration with S = 5/2 local magnetic moments at the Mn atoms. Hole carriers induced by K substitution for Ba atoms go into the top of the As 4p valence band and are weakly bound to the Mn local spins. The ferromagnetic correlation between the local spins mediated by the hole carriers induces ferromagnetism in Ba1-xKx(Zn1-yMny)2As2. [ABSTRACT FROM AUTHOR]

In this paper, we first present a recording physics based analytical channel model for bit-patterned media recording (BPMR) systems with staggered islands configuration. We further propose an analytical approach to jointly design the equalizer with partial response (PR) target for BPMR systems, by using the minimum mean-squared error (MMSE) criterion with monic constraint, taking into account inter-track interference (ITI) and media noise. Simulation results show that the proposed approach performs better than the system designed without considering ITI and media noise. We further investigate the performance of staggered array against regular array islands with bit-aspect ratios (BAR) of 1 and 2, and with different amount of media noise, inter-symbol interference (ISI), and ITI. We found that staggered array islands with BAR of 2 offer better bit error rate (BER) performance and better tolerance to media noise. [ABSTRACT FROM PUBLISHER]

We used x-ray magnetic circular dichroism (XMCD) to probe the ferromagnetic properties of As p-symmetric (4p) states in the recently synthesized diluted magnetic semiconductor (Ba1-xKx)(Zn1-yMny)2As2 system under ambient- and high-pressure conditions. The As K-edge XMCD signal scales with the sample magnetization (dominated by Mn) and scales with the ferromagnetic ordering temperature Tc, and hence it is representative of the bulk magnetization. The XMCD intensity gradually decreases upon compression and vanishes at around 25 GPa, indicating quenching of ferromagnetism at this pressure. Transport measurements show a concomitant increase in conductivity with pressure, leading to a nearly metallic state at about the same pressure where magnetic order collapses. High-pressure x-ray diffraction shows an absence of structural transitions to 40 GPa. The results indicate that the mobility of doped holes, probed by both transport and x-ray absorption spectroscopy (4p band broadening), is intimately connected with the mechanism of magnetic ordering in this class of compounds and that its control using external pressure provides an alternative route for tuning the magnetic properties in diluted magnetic semiconductor materials. [ABSTRACT FROM AUTHOR]

The UASB reactor was applied for biodegradation of organic compounds in coking wastewater. The influent pH ranged between 6.8 and 7.2, and stirring speed and temperature were controlled at 2 r/min and 30 ± 1°C, respectively. The reactor was successfully started up in 133 days. When the influent COD was 2,600 mg/L (VLR was 2.6 kg/m³ d), the removal rate of COD was about 54% and the effluent VFA was below 400 mg/L. GC/MS analysis indicated that the coking wastewater mainly contained aniline, phenol, o-phenol, p-cresol, benzoic acid, indole, quinoline etc. Twenty four kinds of organic compounds were detected in the influent, and 20 kinds of organic compounds were completely removed in the UASB reactor. The biodegradation of organic compounds followed Grau second-order kinetics. It was proved to be an effective and feasible method for coking wastewater anaerobic treatment. [ABSTRACT FROM AUTHOR]

In this research, we report the result of two different methods of making AZO films. In the first method, the AZO film was deposited on silicon wafer and glass substrate using a magnetic controlled RF sputtering system, with rf power (150 W) at two working pressures, 5 mtorr, and 10 mtorr, respectively. The deposition temperatures were 25, 100, 150, 200, and 300 °C, respectively. In the second method, the AZO film was made by sol-gel coating using (CH3COO)2 Zn⋅2H2O mixed with AlCl3⋅6H2O and melting in HOC2H4NH2 and CH3OC2H5OH solvent and annealing at N2 and/or 6% H2/Ar for one hour. The transparencies of the films are all larger than 80%, and the resistivities may reach 10−3 Ω cm. [ABSTRACT FROM AUTHOR]

Self-organized zinc oxide (ZnO) nanofiber network with six-fold symmetry was fabricated on ZnO-buffered (0001) sapphire substrate with patterned gold catalyst by vapor-phase transport method. From the ZnO buffer layer, hexagonal ZnO nanorods with identical in-plane structure grew epitaxially along [0001] orientation to form vertical stems. The nanofiber branches grew horizontally from six side-surfaces of the vertical stem along [0110] and other equivalent directions. The aligned network structure constructed a waveguide array with optical gain. Ultraviolet amplified spontaneous emission was observed along the side-branching nanofibers when the aligned ZnO network was excited by a frequency-tripled Nd:YAG laser. [ABSTRACT FROM AUTHOR]

We investigate doping- and pressure-induced changes in the electronic state of Mn 3d and As 4p orbitals in II-II-V-based diluted magnetic semiconductor (Ba1-x Kx) (Zn1-y Mny)2 As2 to shed light into the mechanism of indirect exchange interactions leading to high ferromagnetic ordering temperature (Tc = 230 K in optimally doped samples). A suite of x-ray spectroscopy experiments (emission, absorption, and dichroism) show that the emergence and further enhancement of ferromagnetic interactions with increased hole doping into the As 4p band is accompanied by a decrease in local 3d spin density at Mn sites. This is a result of increasing Mn 3d - As 4p hybridization with hole doping, which enhances indirect exchange interactions between Mn dopants and gives rise to induced magnetic polarization in As 4p states. On the contrary, application of pressure suppresses exchange interactions. While Mn K β emission spectra show a weak response of 3d states to pressure, clear As 4p band broadening (hole delocalization) is observed under pressure, ultimately leading to loss of ferromagnetism concomitant with a semiconductor to metal transition. The pressure response of As 4p and Mn 3d states is intimately connected with the evolution of the As-As interlayer distance and the geometry of the MnA s4 tetrahedral units, which we probed with x-ray diffraction. Our results indicate that hole doping increases the degree of covalency between the anion (As) p states and cation (Mn) d states in the MnA s4 tetrahedron, a crucial ingredient to promote indirect exchange interactions between Mn dopants and high Tc ferromagnetism. The instability of ferromagnetism and semiconducting states against pressure is mainly dictated by delocalization of anion p states. [ABSTRACT FROM AUTHOR]