Local weak ferromagnetism in single-crystalline ferroelectric BiFeO3

Polarized small-angle neutron scattering studies of single-crystalline multiferroic BiFeO(3) reveal a long-wavelength spin density wave generated by ∼1° spin canting of the spins out of the rotation plane of the antiferromagnetic cycloidal order. This signifies weak ferromagnetism within mesoscopic regions of dimension 0.03 microns along [110], to several microns along [111], confirming a long-standing theoretical prediction. The average local magnetization is 0.06 μ(B)/Fe. Our results provide an indication of the intrinsic macroscopic magnetization to be expected in ferroelectric BiFeO(3) thin films under strain, where the magnetic cycloid is suppressed.

Rev variation during persistent lentivirus infection

The ability of lentiviruses to continually evolve and escape immune control is the central impediment in developing an effective vaccine for HIV-1 and other lentiviruses. Equine infectious anemia virus (EIAV) is considered a useful model for immune control of lentivirus infection. Virus-specific cytotoxic T lymphocytes (CTL) and broadly neutralizing antibody effectively control EIAV replication during inapparent stages of disease, but after years of low-level replication, the virus is still able to produce evasion genotypes that lead to late re-emergence of disease. There is a high rate of genetic variation in the EIAV surface envelope glycoprotein (SU) and in the region of the transmembrane protein (TM) overlapped by the major exon of Rev. This review examines genetic and phenotypic variation in Rev during EIAV disease and a possible role for Rev in immune evasion and virus persistence.

A study on low temperature transport properties of independent double-gated poly-Si nanowire transistors

Employing mix-and-match lithography of I-line stepper and e-beam direct writing, independent double-gated poly-Si nanowire thin film transistors with channel lengths ranging from 70 nm to 5 µm were fabricated and characterized. Electrical measurements performed under cryogenic ambient displayed intriguing characteristics in terms of length dependent abrupt switching behavior for one of the single-gated modes. Through simulation and experimental verification, the root cause for this phenomenon was identified to be the non-uniformly distributed dopants introduced by ion implantation.

Isotopomer fractionation in the UV photolysis of N(2)O: 3. 3D Ab initio surfaces and anharmonic effects

The wavelength-dependent isotopic fractionation of N(2)O is calculated, extending our previous work, Parts 1 and 2, in several aspects: (1) the fully three-dimensional ab initio electronic potential and transition dipole moment surfaces of S. Nanbu and M. S. Johnson (J. Chem. Phys. A 2004, 108, 8905) are used to calculate the absorption cross sections, instead of a 2D surface and (2) the vibrational frequencies and wave functions with anharmonicity correction are used for the ground electronic state. The results for the absorption spectrum and for the isotopic fractionation of the different isotopomers are discussed. One difference between experiments measuring the absorption coefficient (von Hessberg et al. Atmos. Chem. Phys. 2004, 4, 1237) and the others that measure instead the photodissociation is also discussed. Experiments on the quantum yield for wavelengths longer than 200 nm (>50 000 cm(-1)) would be helpful in treating the observed difference.

Core-shell magnetic morphology of structurally uniform magnetite nanoparticles

A new development in small-angle neutron scattering with polarization analysis allows us to directly extract the average spatial distributions of magnetic moments and their correlations with three-dimensional directional sensitivity in any magnetic field. Applied to a collection of spherical magnetite nanoparticles 9.0 nm in diameter, this enhanced method reveals uniformly canted, magnetically active shells in a nominally saturating field of 1.2 T. The shell thickness depends on temperature, and it disappears altogether when the external field is removed, confirming that these canted nanoparticle shells are magnetic, rather than structural, in origin.

Coupled magnetic and ferroelectric domains in multiferroic Ni3V2O8

Electric control of multiferroic domains is demonstrated through polarized magnetic neutron diffraction. Cooling to the cycloidal multiferroic phase of Ni3V2O8 in an electric field E causes the incommensurate Bragg reflections to become neutron spin polarizing, the sense of neutron polarization reversing with E. Quantitative analysis indicates the E-treated sample has a handedness that can be reversed by E. We further show a close association between cycloidal and ferroelectric domains through E-driven spin and electric polarization hysteresis. We suggest that a definite cycloidal handedness is achieved through magnetoelastically induced Dzyaloshinskii-Moriya interactions.

Effect of thimerosal on Ca2+ movement and viability in human oral cancer cells

The effect of thimerosal on cytosolic free Ca2+ concentrations ([Ca2+]i ) in human oral cancer cells (OC2) is unclear. This study explored whether thimerosal changed basal [Ca2+]i levels in suspended OC2 cells using fura-2. Thimerosal at concentrations between 1and 50 μM increased [Ca2+]i in a concentration-dependent manner. The Ca2+ signal was reduced partly by removing extracellular Ca 2+. Thimerosal-induced Ca2+ influx was not blocked by L-type Ca2+ entry inhibitors and protein kinase C modulators (phorbol 12-myristate 13-acetate [PMA] and GF109203X). In Ca2+-free medium, 50 μM thimerosal failed to induce a [Ca2+]i rise after pretreatment with thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor). Inhibition of phospholipase C with U73122 did not change thimerosal-induced [Ca2+]i rises. At concentrations between 5 and 10 μM, thimerosal killed cells in a concentration-dependent manner. The cytotoxic effect of 8 μM thimerosal was potentiated by prechelating cytosolic Ca2+ with the Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetate/acetomethyl (BAPTA/ AM). Flow cytometry data suggested that 1—7 μM thimerosal-induced apoptosis in a concentration-dependent manner. Collectively, in OC2 cells, thimerosal-induced [Ca2+]i rises by causing phospholipase C-independent Ca2+ release from the endoplasmic reticulum and Ca2+ influx through non—L-type Ca2+ channels. Thimerosal killed cells in a concentration-dependent manner through apoptosis.

Interaction of polybrominated diphenyl ethers (PBDEs) with anaerobic mixed bacterial cultures isolated from river sediment

The degradation of flame retardant polybrominated diphenyl ethers (PBDE), including tetra-brominated diphenyl ether (BDE-47), penta-brominated diphenyl ether (BDE-99 and -100), and hexa-brominated diphenyl ether (BDE-153 and -154), by anaerobic bacterial mixed cultures isolated from river sediment was investigated. The effects of PBDEs on changes of anaerobic bacterial community in sediment culture were also studied. Sediments were collected from Er-Jen River and Nan-Kan River basins, which were both heavily polluted rivers in Taiwan, and bacteria from the sediment samples were enriched before the experiment was conducted. Into the anaerobic bacterial mixed cultures, 0.1 microg/mL of PBDEs was added followed by incubation under 30 degrees C for 70 days. Residues of PBDE were determined by gas chromatography with electron capture detector (GC-ECD), and the changes of bacterial community were analyzed by denaturing gradient gel electrophoresis (DGGE). Less than 20% of PBDEs were degraded after 70 days of incubation in all samples except for BDE-47 from the Nan-Kan River sediment. In that culture, BDE-47 was found to have notably degraded. In particular, after 42 days of incubation; BDE-47 was degraded, suddenly and sharply, to a negligible level on Day 70, and the result was confirmed by a repeated experiment. An interesting result was that although BDE-47 was degraded fast in the Nan-Kan River sediment, the bacterial communities did not shift significantly as we had speculated at Day 70. From UPGMA dendrograms, PBDEs changed the composition of bacterial communities, and the extents varied with the variety of PBDE congeners. By the amendment with BDE-153 or -154, bacterial communities would be changed immediately and irreversibly throughout the rest of the incubation period. No significant difference in degradation of PBDEs was observed between sediment bacteria from Er-Jen River and Nan-Kan River. However, the results verified the persistence of PBDEs in the environment.

End-compensated magnetostatic cavity for polarized 3He neutron spin filters

We have expanded upon the "Magic Box" concept, a coil driven magnetic parallel plate capacitor constructed out of mu-metal, by introducing compensation sections at the ends of the box that are tuned to limit end-effects similar to those of short solenoids. This ability has reduced the length of the magic box design without sacrificing any loss in field homogeneity, making the device far more applicable to the often space limited neutron beam line. The appeal of the design beyond affording longer polarized 3He lifetimes is that it provides a vertical guide field, which facilitates neutron spin transport for typical polarized beam experiments. We have constructed two end-compensated magic boxes of dimensions 28.4 x 40 x 15 cm3 (length x width x height) with measured, normalized volume-averaged transverse field gradients ranging from 3.3 x 10(-4) to 6.3 x 10(-4) cm(-1) for cell sizes ranging from 8.1 x 6.0 to 12.0 x 7.9 cm2 (diameter x length), respectively.

Precision measurement of the n-3He incoherent scattering length using neutron interferometry

We report the first measurement of the low-energy neutron-(3)He incoherent scattering length using neutron interferometry: b_{i};{'} = (-2.512 +/- 0.012 stat +/- 0.014 syst) fm. This is in good agreement with a recent calculation using the AV18 + 3N potential. The neutron-(3)He scattering lengths are important for testing and developing nuclear potential models that include three-nucleon forces, effective field theories for few-body nuclear systems, and neutron scattering measurements of quantum excitations in liquid helium. This work demonstrates the first use of a polarized nuclear target in a neutron interferometer.

Effect of Celecoxib on Ca2+Fluxes and Proliferation in MDCK Renal Tubular Cells

The effect of celecoxib on renal tubular cells is largely unexplored. In Madin Darby canine kidney (MDCK) cells, the effect of celecoxib on intracellular CaCa2+ concentration ([Ca2+]i) and proliferation was examined by using the Ca(2 +)-sensitive fluorescent dye fura-2 and the viability detecting fluorescent dye tetrazolium, respectively. Celecoxib (> or =1 micro M) caused an increase of [CaCa2+]i in a concentration-dependent manner. Celecoxib-induced [CaCa2+]i increase was partly reduced by removal of extracellular CaCa2+. Celecoxib-induced CaCa2+ influx was independently suggested by MnCa2+ influx-induced fura-2 fluorescence quench. In Ca(2 +)-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca(2 +)-ATPase, caused a monophasic [CaCa2+]i increase, after which celecoxib only induced a tiny [CaCa2+]i increase; conversely, pretreatment with celecoxib completely inhibited thapsigargin-induced [CaCa2+]i increases. U73122, an inhibitor of phospholipase C, abolished ATP (but not celecoxib)-induced [CaCa2+]i increases. Overnight incubation with 1 or 10 micro M celecoxib decreased cell viability by 80% and 100%, respectively. These data indicate that celecoxib evokes a [CaCa2+]i increase in renal tubular cells by stimulating both extracellular CaCa2+ influx and intracellular CaCa2+ release and is highly toxic to renal tubular cells in vitro.

Safrole-Induced Ca2+Mobilization and Cytotoxicity in Human PC3 Prostate Cancer Cells

The effect of the carcinogen safrole on intracellular Ca2+ mobilization and on viability of human PC3 prostate cancer cells was examined. Cytosolic free Ca2+ levels ([Ca2+]i) were measured by using fura-2 as a probe. Safrole at concentrations above 10 microM increased [Ca2+]i in a concentration-dependent manner with an EC50 value of 350 microM. The Ca2+ signal was reduced by more than half after removing extracellular Ca2+ but was unaffected by nifedipine, nicardipine, nimodipine, diltiazem, or verapamil. In Ca2+-free medium, after treatment with 650 microM safrole, 1 microM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor) failed to release Ca2+. Neither inhibition of phospholipase C with U73122 nor modulation of protein kinase C activity affected safrole-induced Ca2+ release. Overnight incubation with 0.65-65 microM safrole did not affect cell viability, but incubation with 325-625 microM safrole decreased viability. Collectively, the data suggest that in PC3 cells, safrole induced a [Ca2+]i increase by causing Ca2+ release from the endoplasmic reticulum in a phospholipase C- and protein kinase C-independent fashion, and by inducing Ca2+ influx. Safrole can decrease cell viability in a concentration-dependent manner.

Neutron beam effects on spin-exchange-polarized 3He

We have observed depolarization effects when high intensity cold neutron beams are incident on alkali-metal spin-exchange-polarized 3He cells used as neutron spin filters. This was first observed as a reduction of the maximum attainable 3He polarization and was attributed to a decrease of alkali-metal polarization, which led us to directly measure alkali-metal polarization and spin relaxation over a range of neutron fluxes at Los Alamos Neutron Science Center and Institute Laue-Langevin. The data reveal a new alkali-metal spin-relaxation mechanism that approximately scales as sqrt[phi_{n}], where phi_{n} is the neutron capture-flux density incident on the cell. This is consistent with an effect proportional to the concentration of electron-ion pairs but is much larger than expected from earlier work.

Clinical trial: percutaneous acetic acid injection vs. percutaneous ethanol injection for small hepatocellular carcinoma--a long-term follow-up study

BACKGROUND

The long-term outcome of percutaneous acetic acid injection (PAI) and percutaneous ethanol injection (PEI) for treating small hepatocellular carcinoma (HCC) remains unclear.

AIM

To compare the long-term outcome of PAI vs. PEI for treating small HCC.

METHODS

From July 1998 to July 2004, 125 patients with small HCC were enrolled. Seventy patients receiving PAI and 55 patients receiving PEI were enrolled. There were no significant differences in the clinical characteristics between the two groups. Tumour recurrence and survival rates were assessed.

RESULTS

Mean follow-up time was 43 months. The local recurrence rate and new tumour recurrence rate were similar between the PAI and PEI groups. The PAI group had significantly better survival than the PEI group (P = 0.027). Multivariate analysis revealed that PAI was the significant factor associated with overall survival [PAI vs. PEI, RR: 0.639, 95% CI: (0.419-1.975), P = 0.038]. The treatment sessions required to achieve complete tumour necrosis were significantly fewer in the PAI group than in the PEI group (2.4 +/- 1.0 vs. 2.9 +/- 1.3, P = 0.018).

CONCLUSION

Percutaneous acetic acid injection required fewer treatment sessions than PEI and provided better survival after long-term follow-up.

Melittin-induced [Ca2+]i increases and subsequent death in canine renal tubular cells

The effect of melittin on cytosolic free Ca2+ concentration ([Ca2+]i) and viability is largely unknown. This study examined whether melittin alters Ca2+ levels and causes Ca2+-dependent cell death in Madin-Darby canine kidney (MDCK) cells. [Ca2+]i and cell death were measured using the fluorescent dyes fura-2 and WST-1 respectively. Melittin at concentrations above 0.5 μM increased [Ca2+]i in a concentration-dependent manner. The Ca2+ signal was reduced by 75% by removing extracellular Ca2+. The melittin-induced Ca2+ influx was also implicated by melittin-caused Mn2+ influx. After pretreatment with 1 μM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor), melittin-induced Ca2+ release was inhibited; and conversely, melittin pretreatment abolished thapsigargin-induced Ca2+ release. At concentrations of 0.5–20 μM, melittin killed cells in a concentration-dependent manner. The cytotoxic effect of 0.5 μM melittin was nearly completely reversed by prechelating cytosolic Ca2+ with BAPTA. Melittin at 0.5–2 μM caused apoptosis as assessed by flow cytometry of propidium iodide staining. Collectively, in MDCK cells, melittin induced a [Ca2+]i rise by causing Ca2+ release from endoplasmic reticulum and Ca2+ influx from extracellular space. Furthermore, melittin can cause Ca2+-dependent cytotoxicity in a concentration-dependent manner.

Suitability of surface acoustic wave oscillators fabricated using low temperature-grown AlN films on GaN/sapphire as UV sensors

Epitaxial AlN films were prepared on GaN/sapphire using a helicon sputtering system at the low temperature of 300 degrees C. Surface acoustic wave (SAW) devices fabricated on AlN/GaN/sapphire exhibited superior characteristics compared with those made on GaN/sapphire. An oscillator using an AlN/GaN/sapphirebased SAW device is presented. The oscillation frequency decreased when the device was illuminated by ultraviolet (UV) radiation, and the downshift of the oscillation frequency increased with the illuminating UV power density. The results showed that the AlN/GaN/sapphire-layered structure SAW oscillators are suitable for visible blind UV detection and opened up the feasibility of developing remote UV sensors for different ranges of wavelengths on the III-nitrides.

Somatic cell nuclear transfer: Past, present and future perspectives

It is now over a decade since the birth, in 1996, of Dolly the first animal to be produced by nuclear transfer using an adult derived somatic cell as nuclear donor. Since this time similar techniques have been successfully applied to a range of species producing live offspring and allowing the development of transgenic technologies for agricultural, biotechnological and medical uses. However, though applicable to a range of species, overall, the efficiencies of development of healthy offspring remain low. The low frequency of successful development has been attributed to incomplete or inappropriate reprogramming of the transferred nuclear genome. Many studies have demonstrated that such reprogramming occurs by epigenetic mechanisms not involving alterations in DNA sequence, however, at present the molecular mechanisms underlying reprogramming are poorly defined. Since the birth of Dolly many studies have attempted to improve the frequency of development, this review will discuss the process of animal production by nuclear transfer and in particular changes in the methodology which have increased development and survival, simplified or increased robustness of the technique. Although much of the discussion is applicable across species, for simplicity we will concentrate primarily on published data for cattle, sheep, pigs and mice.

Variation in structure and properties of a non-dispersive TTCP/DCPA-derived CPC immersed in Hanks? solution

The present work is to characterize a non-dispersive, fast-setting and high-strength tetra calcium phosphate (TTCP)/dicalcium phosphate anhydrous (DCPA)-based calcium phosphate cement (nd-CPC) recently developed in the authors' laboratory. Comparison between this CPC and a conventional TTCP/DCPA-based CPC (c-CPC) is made. The results show that, during setting c-CPC reaches its pH plateau after 10 min, while nd-CPC approaches plateau after 20 min. During immersion in Hanks' solution the pH values of both cements reach their maxima after immersion for a few days, then decline eventually to near neutrality. With immersion time TTCP and DCPA phases gradually dissolve and apatite phase precipitates. The nd-CPC has a higher apatite formation rate and denser structure than c-CPC under similar conditions, especially at early stage. The nd-CPC also demonstrates higher strength both during setting and after immersion.

PapG II adhesin in the establishment and persistence of Escherichia coli infection in mouse kidneys

Most human pyelonephritogenic Escherichia coli express the PapG II adhesin. However, the role of the PapG II adhesin in enhancing the establishment and persistence of E. coli infection in the kidney is controversial. A pyelonephritogenic strain, EC114, which possesses one copy of the papG II gene, but without other virulence factors (such as S/F1C-fimbriae, hemolysin, and cytotoxic necrotizing factor 1) was selected for the construction of a papG II mutant. The resulting papG II mutant was confirmed by polymerase chain reaction, Southern hybridization, and agglutination assay, and designated as MEC114. We compared MEC114 with the parental strain (EC114) for colonization ability in the bladder and kidney of female BALB/c mice, which were challenged transurethrally with 50 microl of a low (5x10(4) CFU (colony-forming unit)) or high (5x10(8) CFU) dose of EC114 or MEC114 and assessed 1, 3, and 7 days after inoculation. Geometric means of quantitative bacterial counts in the kidney were significantly decreased when challenged with MEC114 on day 3 after inoculation, at both low and high dose (P<0.05), as compared with EC114. On the seventh day, both strains were mainly cleared from the kidney. Renal biopsy showed a similar degree of inflammatory response to both strains 1, 3, and 7 days after inoculation. In brief, the PapG II adhesin can enhance the early establishment of E. coli infection in the kidney, but the bacteria do not maintain infection owing to the host immune response.

Effect of riluzole on Ca2+ movement and cytotoxicity in Madin-Darby canine kidney cells

Riluzole is a drug used in the treatment of amyotrophic lateral sclerosis; however, its in vitro action is unclear. In this study, the effect of riluzole on intracellular Ca2+ concentration ([Ca2+]i) in Madin-Darby canine kidney (MDCK) cells was investigated using the Ca2+ -sensitive fluorescent dye, fura-2. Riluzole (100-500 microM) caused a rapid and sustained increase of [Ca2+]i in a concentration-dependent manner (EC50 = 150 microM). Some 40 and 50% of this [Ca2+]i increase was prevented by the removal of extracellular Ca2+ and the addition of La3+, respectively, but was unchanged by dihydropyridines, verapamil and diltiazem. In Ca2+ -free medium, thapsigargin - an inhibitor of the endoplasmic reticulum (ER) Caz+ -ATPase--caused a monophasic [Ca2+]i increase, after which the increasing effect of riluzole on [Ca2+]i was attenuated by 70%; in addition, pre-treatment with riluzole abolished thapsigargin-induced [Ca2+]i increases. U73122, an inhibitor of phospholipase C (PLC), abolished ATP (but not riluzole)-induced [Ca2+]i increases. At concentrations of 250 and 500 microM, riluzole killed 40 and 95% cells, respectively. The cytotoxic effect of riluzole (250 microM) was unaltered by pre-chelating cytosolic Ca2+ with BAPTA. Collectively, in MDCK cells, riluzole rapidly increased [Ca2+]i by stimulating extracellular Ca2+ influx via an La3+ -sensitive pathway and intracellular Ca2+ release from the ER via, as yet, unidentified mechanisms. Furthermore, riluzole caused Ca2+ -unrelated cytotoxicity in a concentration-dependent manner.