A simple scheme for finding magnetic aromatic hydrocarbon molecules.

Polycyclic aromatic hydrocarbon (PAH) molecules such as quasi-unidimensional oligo-acene and fused azulene display interesting properties for increasing chain length. However, these molecules can be hard to explore computationally due to the number of atoms involved and the fast-increasing numerical cost when using many-body methods. The identification of magnetic PAH molecules is most relevant for technological applications and hence it would be of particular interest to develop rapid preliminary checks to identify likely candidates for both theoretical and experimental pursuits. In this article, we show that an analysis based on a second-order perturbation treatment of electronic correlations for the Hubbard model qualitatively predicts the outcome of more extensive and accurate methods. Based on these results we propose a simple computational protocol for screening molecules and identifying those worthy of a more sophisticated analysis on the magnetic nature of their ground states. Using this protocol we were able to identify two new magnetic molecules made from the combination of only two naphthalene monomers and two azulene ones (both isomers with formula C34H20). For further confirmation of this result, these molecules were also studied by means of density matrix renormalization group and density functional theory.

Building two-dimensional metal-organic networks with tin.

We show that Sn atoms combined with organic ligands can be used to build 2D coordination networks on Au(111) surfaces.

Ubiquitous deprotonation of terephthalic acid in the self-assembled phases on Cu(100).

We performed an exhaustive study of terephthalic acid (TPA) self-assembly on a Cu(100) surface, where first-layer molecules display two sequential phase transitions in the 200-400 K temperature range, corresponding to different stages of molecular deprotonation. We followed the chemical and structural changes by means of high-resolution X-ray photoelectron spectroscopy (XPS) and variable-temperature scanning tunneling microscopy (STM), which were interpreted on the basis of density functional theory (DFT) calculations and photoemission simulations. In order to reveal the spectroscopic contributions of the molecules in different states of deprotonation, we modified the substrate reactivity by deposition of a small amount of Sn, which hampers the deprotonation reaction. We found that the characteristic molecular ribbons of the TPA/Cu(100) α-phase at a low temperature contain a significant fraction of partially deprotonated molecules, in contrast to the expectation of a fully protonated phase, where the self-assembly was claimed to be simply driven by the intermolecular double hydrogen bonds [OHO]. On the basis of our simulations, we propose a model where the carboxylate groups of the partially deprotonated molecules form single hydrogen bonds with the carboxylic groups of the fully protonated molecules. Using real time XPS, we also monitored the kinetics of the deprotonation reaction. We show that the network of mixed single and double hydrogen bonds inhibits further deprotonation up to ∼270 K, whereas the isolated molecules display a much lower deprotonation barrier.

Abiotic degradation of glyphosate into aminomethylphosphonic acid in the presence of metals.

Glyphosate [N-phosphono-methylglycine (PMG)] is the most used herbicide worldwide, particularly since the development of transgenic glyphosate-resistant (GR) crops. Aminomethylphosphonic acid (AMPA) is the main glyphosate metabolite, and it may be responsible for GR crop damage upon PMG application. PMG degradation into AMPA has hitherto been reckoned mainly as a biological process, produced by soil microorganisms (bacteria and fungi) and plants. In this work, we use density functional calculations to identify the vibrational bands of PMG and AMPA in surface-enhanced Raman spectroscopy (SERS) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra experiments. SERS shows the presence of AMPA after glyphosate is deposited from aqueous solution on different metallic surfaces. AMPA is also detected in ATR-FTIR experiments when PMG interacts with metallic ions in aqueous solution. These results reveal an abiotic degradation process of glyphosate into AMPA, where metals play a crucial role.

Anisotropic magnetoresistance in manganites: experiment and theory.

We present measurements of the anisotropic magnetoresistance (AMR) of La(0.75)Sr(0.25)MnO(3) films deposited on (001) SrTiO(3) substrates, and a model that describes the experimental results. The model, based on the electronic structure of manganites plus the spin-orbit coupling, correctly accounts for the dependence of the AMR on the direction of the current to the crystalline axes. We measure an AMR of the order of 10(-3) for the current I parallel to the [100] axis of the crystal and vanishing AMR for I , in agreement with the model predictions. Further, we calculate the planar Hall effect and show its connection to AMR.

The effect of Coulomb interaction at ferromagnetic-paramagnetic metallic perovskite junctions.

We study the effect of Coulomb interactions in transition metal oxide junctions. In this paper we analyze charge transfer at the interface of a three layer ferromagnetic-paramagnetic-ferromagnetic metallic oxide system. We choose a charge model considering a few atomic planes within each layer and obtain results for the magnetic coupling between the ferromagnetic layers. For large numbers of planes in the paramagnetic spacer we find that the coupling oscillates with the same period as in Ruderman-Kittel-Kasuya-Yoshida (RKKY) theory but the amplitude is sensitive to the Coulomb energy. At small spacer thickness however, large differences may appear as a function of the number of electrons per atom in the ferromagnetic and paramagnetic materials, the dielectric constant at each component, and the charge defects at the interface plane, emphasizing the effects of charge transfer.

Hospital mergers: the shift from federal antitrust enforcement to state regulation.

The authors examine and analyze the burgeoning merger activity in the hospital arena, as well as the nonfederal attempts made to regulate that activity. They conclude that the present, ad hoc, system of state regulation is sorely wanting and that it would be preferable if stronger antitrust enforcement and judical decisions prevented competition reducing mergers. If a merger results in a true monopoly (and nonetheless passes antitrust scrutiny), its regulation should be the responsibility of the pertinent state public utility board which, unlike the courts and state attorneys general, has sufficient expertise to adequately regulate the merged entities. Otherwise, the faults of the present system, which is easily manipulated by hospitals seeking political and legal cover for their activities, are likely to be perpetuated.

Hematopoietic differentiation activity of a recombinant human interleukin-6 (IL-6) isoform resulting from alternatively spliced deletion of the second exon.

We have previously identified and cloned an alternatively spliced form of human interleukin-6 mRNA lacking exon II, which encodes amino acid residues known to be important in gp130-mediated signal transduction pathways. We expressed and purified the recombinant protein (rIL6-alt) resulting from this alternatively spliced mRNA and now report the initial characterization of its biologic activities with comparison to full length IL6 (rIL6-full). rIL6-alt was found to have 10(4) to 10(5) fold less activity in proliferation assays with 7TD1 murine plasmacytoma cells and did not competitively inhibit the stimulatory activity of rIL6-full. In addition, like rIL6-full, rIL6-alt had antiproliferative activity toward M1 murine myeloblast cells and was 10-200-fold less active than rIL6-full. In contrast, in assays with human HL60 promyelocytic leukemia cells, rIL6-alt had greater antiproliferative activity than rIL6-full and more strongly upregulated phagocytosis as well as surface expression of the differentiation antigen CD11b. rIL6-full and rIL6-alt upregulated the level of lysozyme mRNA in HL60 cells approximately equally. These findings suggest that IL6-alt, which lacks amino acid residues encoded by the second exon of the gene, is not a natural inhibitor of IL6-full but may be relatively tissue specific and may play a role in modulation of hematopoietic cell growth and differentiation.

Rural hospital mergers, antitrust policy, and the Ukiah case.

This article examines the antitrust issues in rural hospital mergers by focusing on an important antitrust case involving the merger of two small hospitals in Ukiah, California. A key issue in this matter was whether the geographic market served by the merger included a nearby larger city. The economic efficiency of small rural hospitals and the competitive implications of their mergers are examined in the context of the Ukiah case. Economies of scale are shown to be important for small rural hospitals and should mitigate any increase in price. The efficiencies defense is shown to be difficult to make even when economies of scale make the likelihood of efficiencies high. The financial difficulties of many rural hospitals, especially in areas where too many exist, mean that mergers such as this one in Ukiah often are an efficient way to keep these hospitals financially sound and accessible. The Ukiah case suggests the desirability of the merger guidelines that permit most mergers of small rural hospitals.

In vitro effects of boron-containing compounds upon glioblastoma cells.

Boron-neutron capture therapy (BNCT) is currently under investigation as a novel therapeutic modality for glioblastoma. This study was undertaken to determine whether boron-containing compounds 4-borono-2-fluoro-D,L-phenylalanine (FBPA) and FBPA-fructose have direct effects upon kinetics of A172, a glioblastoma cell line. Flow cytometry analyzed cell-cycle distribution and S-phase kinetics (bromo deoxyuridine [BUdR] incorporation). BUdR incorporation was increased during a 1-hr pulse after 24-hr or 72-hr exposure of cells to varying concentrations of FBPA or FBPA-fructose. Results suggest that boron-containing compounds may effect cell kinetics apart from neutron activation, and this effect should be further evaluated for potential impact upon tumor responsiveness to BNCT.

Oral efficacy of a leukotriene B4 receptor antagonist in colitic cotton-top tamarins.

Leukotriene B4 (LTB4) is a potent neutrophil activator and chemotaxin that is present in increased concentrations in the colonic tissue and rectal dialysates of acute ulcerative colitis patients. Cotton-top tamarins (CTTs) with confirmed active colitis were treated with the second generation LTB4 receptor antagonist, SC-53228 ((+)-(S)-7-[3-(2-cyclopropyl-methyl)-3-methoxy-4-[(methylamino) carbonyl]phenoxy]propoxy]-3,4-dihydro-8-propyl-2H-1-benzopyran-2- propanoic acid), 20 mg/kg bodyweight by gavage, twice daily for 56 days. End points were body weights, stool consistency, colonic endoscopy, assay of inflammatory mediators, and haematology and clinical chemistry tests. LTB4 and prostaglandin E (PGE) values were measured in rectal dialysates at pretreatment, 28 day and 56 day time points. LTB4 concentrations were reduced from pretreatment mean (SEM) values of 37.3 (0.8) ng/ml to 3.7 (0.8) ng/ml (p < 0.001) and 2.3 (0.5) ng/ml (p < 0.01) at days 28 and 56, respectively. On the other hand, mucosal protective PGE values remained constant or slightly increased during SC-53228 treatment (pre: 6.9 (2.2) ng/ml; day 28: 6.7 (1.4) ng/ml; day 56: 9.9 (1.6) ng/ml). Furthermore, assessment of a panel of 35 clinical chemistry and haematology parameters throughout the treatment showed there were no significant untoward effects of drug treatment. Six CCTs finished the eight week treatment and five of six gained weight (ranging from 27-121 grams each) while one CTT lost weight (50 g). Stool condition improved in five of six animals while one of six remained unchanged. All CCTs showed dramatic improvement histologically, with no or only minimally active colitis after treatment. The histological changes plus significant weight gains and improvement of stool condition (quality of life parameters) after eight weeks of SC-53228 treatment were remarkable. Furthermore, in follow up biopsies seven months after treatment ceased, three of six CTTs had no active colitis. This is the first time afflicted CTTs have not had recurring colitic exacerbations after a treatment regimen was stopped. It is concluded that in colitic CTTs, SC-53228 has shown both an immediate and a long acting anticolitic activity. It is also concluded that reduced LTB4 concentrations during treatment inhibited neutrophil infiltration of the colonic tissue and this, coupled with the maintenance of mucosal protective prostaglandins, contributed to the dramatic anticolitic efficacy. The treatment was safe over eight weeks. A compound such as SC-53228 may be useful in the medical treatment of human inflammatory bowel disease.

Flow cytometry of liver fine needle aspirates.

Fine needle aspiration analysis of intraabdominal masses is increasing in frequency. This study was designed to evaluate whether flow cytometry could be of value in the cytopathology interpretation of such specimens. Over a 4-year time span, 129 consecutive liver fine needle aspirates were evaluated by flow cytometry for DNA content, ploidy, and proliferation rate. Only excess cells remaining in the needle after cytology samples were prepared were included in this study. Overall sensitivity was 75% and specificity was 94%. In addition, flow cytometry results were pivotal for at least two specimens in achieving the appropriate diagnosis. For these reasons, it was concluded that flow cytometry could be a valuable adjunctive technology, to the cytopathologist in the interpretation of liver fine needle aspirates.

Flow cytometry as a prognostic indicator in women with borderline epithelial ovarian tumors.

Flow cytometry has been used to rapidly and reliably measure DNA content in malignant tumor cells. Although several studies have suggested that DNA ploidy is a powerful predictor of survival in women with epithelial ovarian cancer, few have determined the usefulness of this procedure in women with borderline tumors. Using data from a population-based tumor registry covering all of western Washington State, women who died prior to 1992 as a consequence of developing a borderline ovarian tumor between 1975 and 1986 were compared to an age, histology, and histologic stage-matched sample of women with the same diagnosis still living after at least 5 years of follow-up. Flow cytometry analysis was conducted using sections of tumor from the original paraffin blocks. Overall, 25% of the women who died and 24% of those still alive had aneuploid DNA tumors (odds ratio = 1.2, 95% CI = 0.3-4.9). This lack of association stands in contrast to the strong relationship of aneuploid status to mortality in an earlier, similarly designed, study of borderline ovarian tumors. We believe that additional studies are required prior to concluding that the clinical course of women with borderline tumors can be predicted by the ploidy status of their tumor's DNA.

Evaluation of in vivo breast fine needle aspirates by flow cytometry: an efficacy study.

BACKGROUND: Malignancy of the breast is frequently diagnosed through fine needle aspiration. In the hands of a skilled aspirator and cytopathologist, this can be a highly accurate procedure. PURPOSE: This study was undertaken to evaluate whether sufficient residual cells in the bore of the needle could be harvested and analyzed efficiently by flow cytometry analysis. The goal was then to determine the value of routine flow cytometry as an adjunctive technology in the interpretation of breast fine needle aspirations. METHODS: Cells were rinsed from the needles of 83 consecutive diagnostic fine needle aspirates after preliminary inspection had confirmed adequate material was obtained for cytopathology. Cells were washed, and nuclei prepared by detergent treatment. After ribonuclease treatment, DNA was stained with the fluorescent marker propidium iodide. DNA content per cell was determined by flow cytometry by measurement of right-angle fluorescence. RESULTS: Less than 4% of the samples were rejected for inadequate cell numbers. Flow cytometry criteria for evidence of malignancy included the presence of a DNA aneuploid population or an elevated rate of proliferation (13% or higher) of a diploid population. Accuracy of flow cytometry was based on cytopathologic interpretation in all cases except two which were based on results of excisional biopsy. The sensitivity of the flow cytometry analysis was 76%; the specificity was 100%, with results from flow cytometry pivotal in the correct diagnoses for two patients whose cytopathologic results were equivocal. Analysis of histograms indicated acceptable coefficients of variation for all populations. Gating analysis indicated the suitability of the material for this type of study, with an average of 85% of the events selected, or "gated in." Low recoveries were associated with the presence of necrotic debris in the sample. CONCLUSION: Flow cytometry can be a valuable adjunctive technology, capable of providing the cytopathologist with additional information regarding the character of cells analyzed.

Flow cytometric analysis of pulmonary fluids and cells for the detection of malignancies.

Cells from a pulmonary or bronchial origin were analyzed with flow cytometry to assess the sensitivity and specificity of this method in diagnosing malignancy. In all instances, cells submitted for flow cytometry analysis were excess cells from specimens submitted for routine cytology. Less than 3% of all samples were rejected for insufficient material. Overall sensitivity from all sources was 86%, specificity 96%. Although cytology results were the standard for determining accuracy of flow cytometry, in a few patients cytology appeared normal and initial evidence for malignancy was obtained from flow cytometry. For this reason, flow cytometry may be a valuable adjunctive technology in the diagnosis of malignancy.

Flow cytometric determination of breast tumor heterogeneity.

Flow cytometric analysis was done on the DNA content of nuclei obtained from different sites of small breast tumors. Although specimens for analysis were obtained within a few millimeters of each other, dramatic differences were occasionally observed in the DNA histograms. In a limited study involving 141 consecutive breast specimens submitted for flow cytometry, 52% (74) were found to have at least one DNA aneuploid population. In 18% of DNA aneuploid tumors, one or more specimens from areas grossly identified as tumor had no DNA aneuploid population. Because of the proposed correlation of aneuploidy with a poorer prognosis and possible responsiveness to chemotherapy, multiple sites should be assayed when flow cytometric DNA analysis is done.