Can an electric field induce an antiferroelectric phase out of a ferroelectric phase?

It has been widely accepted that electric fields favor the ferroelectric phase with parallel electric dipoles over the antiferroelectric phase. With detailed measurements in polycrystalline ceramics of Pb(0.99)Nb(0.02[(Zr(0.57)Sn(0.43)(1-y)Ti(y)](0.98)O(3), we demonstrate in this Letter that electric fields can induce an antiferroelectric phase out of a ferroelectric phase, i.e., trigger an apparently unlikely ferroelectric-to-antiferroelectric phase transition. We suggest that it is caused by the volume contraction from the converse piezoelectric effect at the coercive field with a reversed polarity.

Increased aortic atherosclerotic plaque development in female apolipoprotein E-null mice is associated with elevated thromboxane A2 and decreased prostacyclin production

The production of thromboxane A(2) (TXA(2)) and prostacyclin (prostaglandin I(2), PGI(2)) is known to be increased in patients with atherosclerosis. In this study, we evaluated the influence of gender on TXA(2) and PGI(2) production, and their association with the progression of atherosclerosis in apolipoprotein E-null (ApoE(-/-)) mice maintained on a high fat diet for 3 months. En face analyses of aortas showed marked increases in plaque formation in female ApoE(-/-) mice. Quantification of the hematoxylin/eosin (H&E) stained cross sections of the aortic arch revealed 3 to 4-fold higher plaque thickness in female ApoE(-/-) mice. Analyses of 24-hours urine samples for 11-dehydro TXB(2) and 2, 3-dinor-6-keto PGF(1a) indicated that female ApoE(-/-) mice produce up to 15-fold more TXA(2) and 50% less PGI(2) than the age matched males. Interestingly, the serum cholesterol levels in ApoE(-/-) females were 20% lower than males on the high fat regimen. No gender-associated changes in the number of T lymphocytes, mast cells and macrophages were evident in the lesion areas of ApoE(-/-) mice. The results suggest that the markedly elevated TXA(2) production and reduced PGI(2) production are gender-related proatherogenic risk factors in female ApoE(-/-) mice.

Effects of physicochemical factors on Cr(VI) removal from leachate by zero-valent iron and alpha-Fe(2)O(3) nanoparticles

The effects of nanoparticle dosage, initial hexavalent chromium concentration, pH value, reaction temperature, and initial concentration of humic acid (HA) on chromate (CrO(4)(2-)) removal from landfill leachate by nanoscale zero-valent iron (NZVI) and hematite (alpha-Fe(2)O(3)) nanoparticles were examined in the present investigations. The Cr(VI) removal rate decreased as the initial Cr(VI) concentration and the reaction temperature increased, whereas corresponding removal rate by NZVI was higher than that of alpha-Fe(2)O(3). The optimum pH for the removal of Cr(VI) by NZVI was found to be 5.0 and more than 99.0% of Cr(VI) was removed within 5 h. However, the removal rate by alpha-Fe(2)O(3) decreased as pH increased. Presence of HA resulted in substantial reduction in the rate and extent of Cr(VI) removal by NZVI, whereas Cr(VI) removal rate by alpha-Fe(2)O(3) did not significantly decrease as HA concentration increased from 0.5 g/L to 3.0 g/L. Increasing the dosage of nanoparticles enhanced the rate constant and the removal of Cr(VI) by NZVI and alpha-Fe(2)O(3) followed pseudo-first-order reaction kinetics. The information should be very useful for the successful application of NZVI and alpha-Fe(2)O(3) for the treatment of groundwater or raw wastewater.

Effect of oxygen content on the magnetic properties of multiferroic YMn(2)O(5+δ)

The effect of oxygen content on magnetic properties in the multiferroic YMn(2)O(5+δ) system was investigated with samples prepared under different oxygen pressures. Our results show that, with increasing oxygen content, the magnetic response changes from being dominated by the anomaly at ∼45 K to the one around 20 K. However, specific heat measurements and neutron powder diffraction studies indicate that the presence of the magnetic transition at ∼45 K is independent of oxygen content. The results suggest that oxygen nonstoichiometry can be one important degree of freedom in manipulating the multiferroic properties.

Exenatide prevents fat-induced insulin resistance and raises adiponectin expression and plasma levels

BACKGROUND

Exenatide (exendin-4) can reduce blood glucose levels, increase insulin secretion and improve insulin sensitivity through mechanisms that are not completely understood.

METHODS

In the present study, we examined the effects of exenatide treatment on glucose tolerance (intravenous glucose tolerance test), insulin sensitivity (euglycaemic-hyperinsulinaemic clamps), insulin signalling (insulin receptor substrate 1 tyrosine phosphorylation) and adipocytokine levels (visfatin and adiponectin) in high fat-fed rats.

RESULTS

Administration of exenatide (0.5 or 2.0 mug/kg twice daily x 6 weeks) prevented high-fat diet (HFD)-induced increases in body weight, plasma free fatty acids, triglycerides and total cholesterol. Exenatide also prevented HFD-induced deterioration in peripheral and hepatic insulin sensitivity, insulin clearance, glucose tolerance and decreased tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) in fat and skeletal muscles. Interestingly, plasma visfatin levels decreased in exenatide-treated rats, whereas expression and plasma levels of adiponectin increased.

CONCLUSIONS

These results indicate that chronic exenatide treatment enhances insulin sensitivity and protects against high fat-induced insulin resistance.

Expression and distribution of S-100, CD83 and apoptosis-related proteins (Fas, FasL and Bcl-2) in tissues of thyroid carcinoma

Previous studies have shown that dendritic cells (DCs) and apoptosis play a critical role in the pathogenesis of thyroid carcinoma (TC). This study was designed to investigate the expression and distribution of S-100 protein, CD83 and apoptosis-related proteins (Fas, FasL and Bcl-2) in the thyroid tissues of thyroid papillary carcinoma (TPC) and their role in TPC pathogenesis. Immunohistochemical staining techniques and other methods were used on pathological tissues of 30 patients with Thyroid papillary carcinoma (TPC) and 30 cases of thyroid follicular adenoma (TFA,as control) to detect the expression and distribution of S-100 protein, CD83, Fas, FasL and Bcl-2. A higher expression of S-100 protein in TPC (4.6+/-3.2%) vs.TFA (0.95+/-0.64%) (p<0.001) was observed as well as a higher expression of CD83 in the peri-cancerous tissues (PCT) (32.51+/-22.32) vs. TFA (5.19+/-8.08) (p<0.001), oppositely, CD83 was negative in the cancerous net.TPC showed greater increases in levels of Fas, FasL and Bcl-2 than did the TFA. Our findings suggest that impaired immune function, absence of CD83-positive mature and activated dendritic cells in cancer nodules may have a role in the pathogenesis of thyroid papillary carcinoma.The regulation of Fas, FasL and Bcl-2 in TPC may help them evade the immune system.

Rapid discovery and optimization of therapeutic antibodies against emerging infectious diseases

Using a comprehensive set of discovery and optimization tools, antibodies were produced with the ability to neutralize SARS coronavirus (SARS-CoV) infection in Vero E6 cells and in animal models. These anti-SARS antibodies were discovered using a novel DNA display method, which can identify new antibodies within days. Once neutralizing antibodies were identified, a comprehensive and effective means of converting the mouse sequences to human frameworks was accomplished using HuFR™ (human framework reassembly) technology. The best variant (61G4) from this screen showed a 3.5–4-fold improvement in neutralization of SARS-CoV infection in vitro. Finally, using a complete site-saturation mutagenesis methodology focused on the CDR (complementarity determining regions), a single point mutation (51E7) was identified that improved the 80% plaque reduction neutralization of the virus by greater than 8-fold. These discovery and evolution strategies can be applied to any emerging pathogen or toxin where a causative agent is known.

Surface energy of nanowires

An analytical model is developed for calculation of the surface energy of a nanowire based on thermodynamics and continuum medium mechanics. The core-shell structure and the outer surface skin of the nanowire are considered for the one-dimensional nanostructure and contributions from chemical and structural effects to the surface energy are discussed. It is found that the surface energy of nanowires decreases with the diameter reduction, which induces the melting temperature depression of nanowires. Theoretical results are in agreement with the results of experiments and simulations.

Photo-induced lipid peroxidation of erythrocyte membranes by a bis-methanophosphonate fullerene

Using human erythrocyte membranes (EMs) as a model system, we have examined photo-induced lipid peroxidation by a bis-methanophosphonate fullerene (BMPF) and four other fullerene derivatives including a mono-methanophosphonic acid fullerene (MMPF), a dimalonic acid C(60) (DMA C(60)), a trimalonic acid C(60) (TMA C(60)) and a polyhydroxylated fullerene (fullerol). Lipid peroxidation was assessed as the malondialdehyde (MDA) level measured by the thiobarbituric acid assay. It was observed that BMPF increased the MDA level of EMs after irradiation in both time- and dose-dependent manners. The photo-induced activity became very significant (p<0.01) under the conditions of either the concentration of 10 microM and irradiation time of 30 min or the concentration of 5 microM and irradiation time of 60 min. Involvement of reactive oxygen species (ROS) in the activity was also examined by specific inhibitors of singlet oxygen, superoxide anions and hydroxyl radicals, respectively. While all three kinds were found responsible for the activity, the former two might play more important roles than the last one. Furthermore, the activity of BMPF was the strongest among all tested fullerene derivatives. These results indicated BMPF was a potential photosensitizer that would find application in photodynamic therapy.

No interaction between the serotonin transporter polymorphism (5-HTTLPR) and childhood adversity or recent stressful life events on symptoms of depression: results from two community surveys

In this study we investigated interactions between the 5-HTTLPR genotype and environmental risk factors (G x E) on symptoms of depression in two large Australian community samples of adolescents and young adults. We postulated that a significant interaction between the 5-HTTLPR genotype and environmental risk factors of childhood adversity or stressful life events on symptoms of depression would be observed in subjects with at least one short allele (s/l or s/s) compared with subjects with no short alleles (l/l). We did not find significant G x E interactions between the 5-HTTLPR genotype and recent stressful life events or childhood adversity on symptoms of depression in our sample populations. However, we did find adolescents aged 17-18 years homozygous for the long allele (l/l) and exposed to persistently high levels of family adversity over a 6-year period were at a greater risk of depression than subjects with the same genotype exposed to no or persistently low levels of family adversity. This interaction should be interpreted cautiously due to the small number of depressed subjects in the sample with persistently high levels of family adversity.

Roughing titanium quantum wire on patterned monohydride diamond (001) surface

The authors have performed the roughing of titanium (Ti) quantum wires forming on a hydrogen-terminated diamond (001)-2x1 surface patterned with an ordered bare strip array and demonstrated that well-ordered Ti quantum wires are achieved only if the growth conditions (temperature and flux) have optimal values via kinetic Monte Carlo simulations. Considering that a scanning tunneling microscope is capable of selectively desorbing H from diamond (001)-2x1-H surface, they proposed a viable and easy approach to fabricate "ideal quantum wires" on the patterned hydrogen-terminated diamond (001) surface. The physical origin of the Ti quantum wire formation was pursued.

S1(A11)←S0(A11) transition of benzo[g,h,i]perylene in supersonic jets and rare gas matrices

The study of the S1(1A1)<--S0(1A1) transition of benzo[g,h,i]perylene (BghiP, C22H12) in supersonic jets and solid rare gas matrices is reported. In the jet-cooled spectrum, the origin band position is located at 25,027.1+/-0.2 cm-1, the assignment being supported by the analysis of vibrational shifts and rotational band contours. Except for the origin band, which is weak, all bands are attributed to the fundamental excitation of nontotally symmetric b1 vibrational modes of S1. The intensity pattern is interpreted as a consequence of the weak oscillator strength of the electronic transition combined with intensity-borrowing through vibronic interaction between the S1(1A1) and S2(1B1) states. The spectra of the S1(1A1)<--S0(1A1) and S2(1B1)<--S0(1A1) transitions have also been measured for BghiP in solid neon and argon matrices. The comparison of the redshifts determined for either transition reveals that the polarizability of BghiP is larger in its S2 than in its S1 state. Bandwidths of 2.7 cm-1 measured in supersonic jets, which provide conditions relevant for astrophysics, are similar to those of most diffuse interstellar bands. The electronic transitions of BghiP are found to lie outside the ranges covered by present databases. From the comparison between experimental spectra and theoretical computations, it is concluded that the accuracy of empirical and ab initio approaches in predicting electronic energies is still not sufficient to identify astrophysically interesting candidates for spectroscopic laboratory studies.

Changes in pulmonary arteriole protein kinase cαexpression associated with supplementalL-arginine in broilers during cool temperature exposure

The present study was conducted to examine the effect of supplemental L-arginine on pulmonary arteriole protein kinase Calpha (PKCalpha) expression in broilers exposed to cool temperature, to investigate further the molecular mechanisms of supplemental L-arginine on modulating pulmonary vascular functions in hypertensive broilers. Broilers were subjected to sub-thermoneutral (cool) temperature to induce pulmonary hypertension syndrome (PHS), and an additional 10 g/kg L-arginine was added to the basal diet to evaluate the effects of supplemental L-arginine on PHS mortality, plasma nitric oxide (NO) production and pulmonary arterioles PKCalpha expression. Supplemental L-arginine reduced PHS mortality but did not affect right/total ventricle (RV/TV) ratios in clinically healthy birds. Birds fed additional L-arginine had increased plasma NO and decreased PKCalpha protein expression in pulmonary arterioles; NO production was negatively correlated with PKCalpha expression. These results demonstrated that supplemental L-arginine diminished PKCalpha expression in birds exposed to cool temperature. It is suggested that NO-induced loss of PKCalpha expression might be partially responsible for its effects on dilating pulmonary vasculature and inhibiting pulmonary vascular remodelling in vivo.