Multicomponent Ceramic Powder Generation by Spray Pyrolysis

We have examined methods for controlling the morphology and microstructure of ceramic particles produced by spray pyrolysis. A variety of materials were examined including SrTiO3and BaTiO3 and the oxides of Al, Mg, Zn, Pd, V, Mo, and Bi. The morphology of the particles was influenced by using colloidal precursors in combination with molecular precursors for particle generation. Slow drying rates obtained by using high relative humidities and controlled axial temperature gradients did not influence particle morphology for the systems and conditions studied. The microstructure of Al2O3, V2O5, and PdO particles was controlled by varying the temperature to provide nanocrystalline or single-crystal particles. Evaporation and condensation of volatile species such as MoO3 and V2O5 dramatically modified particle microstructure and morphology.

Pseudolayered structure of the columnar B1 phase of bent-core liquid crystals

Three bent-core liquid-crystal compounds presenting the unusual columnar B1 to tilted polar smectic (Sm-CP or B2) phase transition are studied through small-angle x-ray diffraction on aligned samples. The well-established character of the smectic phase helps to characterize the structural changes during the transition. A mechanism for this transition is proposed, which accounts for the low enthalpy usually observed in this process. The B1 phase is found to possess a great degree of lamellarization, with pseudosmectic ferroelectric layers along the crystallographic (11) planes. As a consequence of these observations a distribution of the block polarizations in the columnar structure is proposed.

No-touch hepatic hilum technique to treat early portal vein thrombosis after pediatric liver transplantation

A 'no-touch' hilum technique used to treat early portal vein complications post-liver transplantation in five children with body weight <10 kg is described. Four patients developed thrombosis and one portal flow absence secondary to collateral steal flow. A vascular sheath was placed through the previous laparotomy in the ileocolic vein (n = 2), inferior mesenteric vein (n = 1) or graft umbilical vein (n = 1). Portal clots were mechanically fragmented with balloon angioplasty. In addition, coil embolization of competitive collaterals (n = 3) and stent placement (n = 1) were performed. The catheter was left in place and exteriorized through the wound (n = 2) or a different transabdominal wall puncture (n = 3). A continuous transcatheter perfusion of heparin was subsequently administered. One patient developed recurrent thrombosis 24 h later which was resolved with the same technique. Catheters were removed surgically after a mean of 10.6 days. All patients presented portal vein patency at the end of follow-up. Three patients are alive after 5 months, 1.5 and 3.5 years, respectively; one patient required retransplantation 18 days postprocedure and the remaining patient died of adenovirus infection 2 months postprocedure. In conclusion, treatment of early portal vein complications following pediatric liver transplantation with this novel technique is feasible and effective.

Barrier formation and charging energy for a variable nanogap organic molecular junction: a tip/C60/Au(111) configuration

We analyze the nanogap organic molecular junction formed by a C(60) molecule in between an Au-tip and an Au(111)-surface. In our approach, we first calculate the atomic geometry of the tip/C(60)/Au(111) nanocontact as a function of the tip-surface distance and molecule adsorption site using a density functional theory-local density approximation (DFT-LDA) technique. The electronic structure and metal/organic barrier height formation (for a single molecule) are analyzed using the induced density of interface states model for metal/organic interfaces. From this analysis we calculate the charging energy U(eff) of the C(60) molecule at the nanocontact and determine self-consistently the transport energy gap and the organic molecule density of states. Our results are shown to be in good agreement with the experimental evidence.

Relationship between insulin resistance, inflammation and liver cell apoptosis in patients with severe obesity

BACKGROUND

In obesity, insulin resistance appears frequently after activation of proinflammatory molecules. Caspase-generated cytokeratin-18 (CK-18) fragments are produced during the apoptosis of hepatic cells. The main objective in the present study is to investigate the relationship between insulin resistance and caspase-generated CK-18 fragments in patients with severe obesity.

METHODS

Sixty-two patients selected for bariatric surgery were clinically studied (sex, age, weight, waist diameter, body mass index, arterial pressure and type 2 diabetes mellitus) and analytic parameters were measured in blood (glucose concentration, cholesterol, triglycerides, insulin, glycosylated hemoglobin, aspartate aminotransferase, alanine aminotransferase, high-sensitivity C-reactive protein, adiponectin, interleukin 6, interleukin 18 and CK-18 fragments). Patient group division was based on 70th percentile of insulin resistance as measured by homeostasis model assessment (HOMA) and also according to liver histology.

RESULTS

Patients with greater insulin resistance (percentile > 70th) showed higher values of CK-18 fragments, interleukin 6 and transaminases. A positive correlation between the HOMA score, value of CK-18 fragments and triglyceride level was found. A correlation between CK-18 fragments with interleukin 6, triglycerides and transaminases was also observed. HOMA score and value of CK-18 fragments correlated with the degree of liver fibrosis.

CONCLUSIONS

Greater degree of insulin resistance induces apoptosis of hepatic cells as measured by the serum levels of CK-18 fragments.

Zygomycotic Lymphadenitis in Slaughtered Feedlot Cattle

During the 12 months of 2006, zygomycotic lymphadenitis was diagnosed in 194 of 198 feedlot steers (0.04% of cattle slaughtered during that period) in a California slaughterhouse as part of bovine tuberculosis surveillance. Mesenteric lymph nodes were involved in 190 cases. Affected lymph nodes were enlarged (2 to 42 cm in greatest dimension), firm, and mottled gray-white to yellow with multiple granular or caseocalcareous foci. Histologically, nodal architecture was effaced by necrosis, granulomatous inflammation, and fibrosis. In approximately 20% of the cases, granulomas were mainly restricted to subcapsular sinuses and afferent lymphatic vessels, causing granulomatous lymphangitis. Nonseptate, irregularly branching hyphae with nonparallel walls and bulbous enlargements were common in necrotic areas and within the cytoplasm of multinucleated giant cells. Fungal cultures were performed on 124 affected lymph nodes using 7 media, but no zygomycetes were cultured. Fungal DNA was amplified from 20 lymph nodes. Amplicons from 16 nodes had nearly 100% homology with sequences for Rhizomucor pusillus; 4 amplicons had (> 98%) homology with Absidia corymbifera sequences. Zygomycosis should be considered in the differential diagnosis for granulomatous lymphadenitis in feedlot steers.

Soluble oligomeric forms of beta-amyloid (Abeta) peptide stimulate Abeta production via astrogliosis in the rat brain

The aim of this study was to investigate the interaction between beta-amyloid (Abeta) peptide and astrogliosis in early stages of Abeta toxicity. In Wistar rats, anaesthetised with equitesine, a single microinjection of Abeta1-42 oligomers was placed into the retrosplenial cortex. Control animals were injected with Abeta42-1 peptide into the corresponding regions of cerebral cortex. Immunocytochemical analysis revealed an intense Abeta immunoreactivity (IR) at the level of Abeta1-42 injection site, increasing from the first 24 h to later (72 h) time point. Control injection showed a light staining surrounding the injection site. In Abeta oligomers-treated animals, Abeta-immunopositive product also accumulates in cortical cells, particularly in frontal and temporal cortices at an early (24 h) time point. Abeta-IR structures-like diffuse aggregates forms were also observed in hippocampus and in several cortical areas, increasing from the first 24 h to later (72 h) time point. In control animals no specific staining was seen neither in cortical cells nor in structures-like diffuse aggregates forms. Injections of Abeta oligomers also induce activation of astrocytes surrounding and infiltrating the injection site. Astrocyte activation is evidenced by morphological changes and upregulation of glial fibrillary acidic protein (GFAP). By GFAP immunoblotting we detected two immunopositive protein bands, at 50 and 48 kDa molecular mass. Confocal analysis also showed that GFAP co-localized with Abeta-IR material in a time-dependent manner. In conclusion, our results indicate that astrocyte activation might have a critical role in the mechanisms of Abeta-induced neurodegeneration, and that should be further studied as possible targets for therapeutic intervention in AD.

Modelling energy level alignment at organic interfaces and density functional theory

A review of our theoretical understanding of the band alignment at organic interfaces is presented with particular emphasis on the metal/organic (MO) case. The unified IDIS (induced density of interface states) and the ICT (integer charge transfer) models are reviewed and shown to describe qualitatively and semiquantitatively the barrier height formation at those interfaces. The IDIS model, governed by the organic CNL (charge neutrality level) and the interface screening includes: (a) charge transfer across the interface; (b) the "pillow" (or Pauli) effect associated with the compression of the metal wavefunction tails; and (c) the molecular dipoles. We argue that the ICT-model can be described as a limiting case of the unified IDIS-model for weak interface screening. For a fully quantitative understanding of the band alignment at organic interfaces, use of DFT (density functional theory) or quantum chemistry methods is highly desirable. In this Perspective review, we concentrate our discussion on DFT and show that conventional LDA or GGA calculations are limited by the "energy gap problem of the organic materials", because the LDA (or GGA) Kohn-Sham energy levels have to be corrected by the self-interaction energy of the corresponding wavefunction, to provide the appropriate molecule transport energy gap. Image potential and polarization effects at MO interfaces tend to cancel these self-interaction corrections; in particular, we show that for organic molecules lying flat on Cu and Ag, these cancellations are so strong that we can rely on conventional DFT to calculate their interface properties. For Au, however, the cancellations are weaker making it necessary to go beyond conventional DFT. We discuss several alternatives beyond conventional LDA or GGA. The most accurate approach is the well-known GW-technique, but its use is limited by its high demanding computer time. In a very simple approach one can combine conventional DFT with a "scissor" operator which incorporates self-interaction corrections and polarization effects in the organic energy levels. Hybrid potentials combined with conventional DFT represent, probably, the best alternative for having a simple and accurate approach for analyzing organic interfaces. The problem then is to find an appropriate one for both the metal and the organic material in a plane-wave formulation; we show, however, how to overcome this difficulty using a local-orbital basis formulation. As examples of these alternatives, we present some DFT-calculations for several organic interfaces, using either the scissor operator or a hybrid potential, which can be interpreted in terms of the unified IDIS-model.

[Proposal for a new microsurgical model for the study of induced endometriosis in Wistar rats. Preliminary results]

The current knowledge status on the patogenesis of endometriosis as well as devastating consequences of disease evolution in women's reproductive health, have promoted researchers advances in a great manner during last years. The immunologic and neangiogenesis systems implication have opened new ways of knowledge over classic theories from the beginning of the xx century. The experimental resesearch, using animal induction models. Below we explain the first steps a new induction model ("PGR1-HotDog"), based on Wistar rats using a new disease autogeneration system, created for te study of the early stages of the endometriosis.

Mechanism of the band gap opening across the order-disorder transition of Si(111)(4 x 1)-In

The ground state properties of indium atom chains on the Si(111) 8 x 2-In surface and the nature of their insulator-metal (IM) transition near 120 K are under intense dispute. We compare experimental scanning tunneling microscopy (STM) images of the low temperature (LT) 8 x 2 phase with STM image calculations from Density Functional Theory (DFT). Our LT studies clearly indicate the existence of a frozen shear distortion between neighboring atom chains, resulting in the formation of indium hexagons. Tunneling spectra furthermore indicate that the IM transition coincides with the collapse of a approximately 0.3 eV surface-state band gap at the Gamma point of the 4 x 2 Brillouin zone. This implies that the IM transition is driven by a shear phonon, not by Fermi surface nesting.

Initial stages of the contact between a metallic tip and carbon nanotubes

We present an experimental and theoretical study of the interaction between a tip and single-walled carbon nanotubes (SWCNT) lying on a SiO2 surface. Adhesion and jump-to-contact forces (JC) are measured in a high vacuum system for SWCNT with diameters (D) ranging from 1.4 to 4.5 nm; we find adhesion forces approximately 3.2 nN and JC forces approximately 2.4 nN. Simulations yield adhesion forces in agreement with experiment showing that for D approximately 1.4 nm half of this force is due to tip-SWCNT and tip-SiO2 van der Waals interactions.

Polar structures of bent-core liquid crystals with tetrathiafulvalene units

We report on a series of three bent-core liquid crystals containing tetrathiafulvalene units. Their characterization consisted of electro-optical observations, second-harmonic generation (SHG) analysis, and x-ray diffraction measurements. Compound I exhibits a lamellar optically isotropic phase on cooling from the isotropic liquid and undergoes a nonreversible field-induced transition to a birefringent state. The two others present two-dimensional structural periodicities, being only compound II switchable. Additionally, the electron density maps of compounds II and III have been obtained based on the analysis of the x-ray diffraction intensities. According to SHG measurements the ground state is antiferroelectric in the three compounds. A quite good SHG performance is found in compounds I and II.

Post-treatment hemodynamics of a basilar aneurysm and bifurcation

To investigate whether or not a successful aneurysm treatment procedure can subject a parent artery to harmful hemodynamic stresses, computational fluid dynamics simulations are performed on a patient-specific basilar aneurysm and bifurcation before and after a virtual endovascular treatment. Prior to treatment, the aneurysm at systole is filled with a periodic train of vortex tubes, which form at the aneurysm neck and advect upwards into the dome. Following the treatment procedure however, the motion of the vortex train is inhibited by the aneurysm filling material, which confines the vortex tubes to the region beneath the aneurysm neck. Analysis of the post-treatment flow field indicates that the impingement of the basilar artery flow upon the treated aneurysm neck and the close proximity of a vortex tube to the parent artery wall increase the maximum wall shear stresses to values approximately equal to 50 Pa at systole. Calculation of the time-averaged wall shear stresses indicates that there is a 1.4 x 10(-7) m(2) area on the parent artery exposed to wall shear stresses greater than 37.9 Pa, a value shown by Fry [Circ. Res. 22(2):165-197, 1968] to cause severe damage to the endothelial cells that line the artery wall. The results of this study demonstrate that it is possible for a treatment procedure, which successfully isolates the aneurysm from the circulation and leaves no aneurysm neck remnant, to elevate the hemodynamic stresses to levels that are injurious to the artery wall.

Mechanical and electrical properties of stretched clean and H-contaminated Pd-nanowires

We analyze theoretically the formation of stretched Pd-nanowires and their interaction with hydrogen. In our approach, we simulate the nanowire stretching process using a first-principles molecular-dynamics method to obtain realistic atomic geometries of the contact in its final stages before the nanowire breaks. The electrical conductance of the nanowire is also calculated at each point of the deformation path. For the clean Pd-nanowire in the last stages of the deformation process we find that the nanowire develops, first, a one-atom-neck and, at the end, a dimer whose bond is finally broken. For these atomic configurations, the calculated electrical conductances are in good agreement with the experimental evidence. The interaction with hydrogen is analyzed adsorbing one or two H atoms on the Pd-nanowire for different configurations along the stretching process. In the case of one H atom we obtain geometries with conductances in the range 0.8-1.4G(0), while for two H atoms we find conductance plateaus with values ∼0.5G(0) and ∼1.0G(0). These results are in excellent agreement with the experimental evidence for nanocontact breaking in an H(2) atmosphere and indicate that the conductance peak around 0.5G(0) observed experimentally is associated with nanowires where two H atoms have been adsorbed.