Structural, chemical, and magnetic investigation of a graphene/cobalt/platinum multilayer system on silicon carbide.

We investigate the magnetic interlayer coupling and domain structure of ultra-thin ferromagnetic (FM) cobalt (Co) layers embedded between a graphene (G) layer and a platinum (Pt) layer on a silicon carbide (SiC) substrate (G/Co/Pt on SiC). Experimentally, a combination of x-ray photoemission electron microscopy with x-ray magnetic circular dichroism has been carried out at the Co L-edge. Furthermore, structural and chemical properties of the system have been investigated using low energy electron diffraction (LEED) and x-ray photoelectron spectroscopy (XPS).In situLEED patterns revealed the crystalline structure of each layer within the system. Moreover, XPS confirmed the presence of quasi-freestanding graphene, the absence of cobalt silicide, and the appearance of two silicon carbide surface components due to Pt intercalation. Thus, the Pt-layer effectively functions as a diffusion barrier. The magnetic structure of the system was unaffected by the substrate's step structure. Furthermore, numerous vortices and anti-vortices were found in all samples, distributed all over the surfaces, indicating Dzyaloshinskii-Moriya interaction. Only regions with a locally increased Co-layer thickness showed no vortices. Moreover, unlike in similar systems, the magnetization was predominantly in-plane, so no perpendicular magnetic anisotropy was found.

Structural, chemical, and magnetic properties of cobalt intercalated graphene on silicon carbide.

We report on a study of the Co intercalation process underneath the [Formula: see text] R30° reconstructed 6H-SiC(0001) surface for Co film-thicknesses in a range of 0.4-12 nm using a combination of surface sensitive imaging, diffractive, and spectroscopic methods. In situ photoemission electron microscopy reveals a dependence of the intercalation temperature on the Co film-thickness. Using low energy electron diffraction and photoemission spectroscopy (XPS), we find that the SiC surface reconstruction is partially lifted and transformed. We show that the [Formula: see text] R30° reconstruction does not prevent silicide formation for Co film-thicknesses  ≥0.4 nm according to XPS and x-ray absorption spectra. Our results indicate that the silicide formation is self-limited to a thin interface region and is followed by Co intercalation between graphene and silicide. Furthermore, we analyze the magnetic properties using x-ray magnetic circular dichroism at the Co L-edge. In-plane magnetization is observed for all analyzed film-thicknesses. For ultra-thin Co films, self-assembled magnetic wires with a width of the order of 100 nm form at the step-edges.

Assessing long-term effects of trauma: diagnosing symptoms of avoidance and numbing.

OBJECTIVE: This study compared the discovery of posttraumatic stress disorder (PTSD) symptoms by means of the Structured Clinical Interview for DSM-III-R (SCID) with a semistructured, psychodynamic clinical interview in a long-term follow-up of the survivors of the Buffalo Creek (W.Va.) flood. METHOD: Videotaped semistructured, psychodynamic clinical interviews of a small group of survivors (N=6) were compared with the results obtained in a prior group-level SCID investigation. RESULTS: Seventy-two percent of the total PTSD symptoms for the subjects studied were elicited exclusively by the psychodynamic clinical interview. PTSD cluster C symptoms of avoidance and numbing of general responsiveness were especially sensitive to discovery by this method. CONCLUSIONS: The psychodynamic clinical interview should be included in the design of studies that seek to investigate long-term effects of trauma, which are especially likely to be manifest in negative symptoms and subtle character change.

Cholesterol embolization to the coronary arteries resulting in acute myocardial infarction: A complication of coronary artery bypass grafting surgery.

Cholesterol emboli dislodged during coronary artery bypass surgery may be released downstream into the native coronary arteries and lead to the development of acute myocardial infarction. An autopsy-proven case of such an event occurring in a 79-year-old woman illustrates this complication of coronary artery bypass surgery. Awareness of this complication by pathologists may facilitate its recognition. Awareness by surgeons, on the other hand, may help to prevent it through decreased intraoperative manipulation of the involved vessels.

The significance of anticardiolipin antibodies and anti-heart muscle antibodies for the diagnosis of postpericardiotomy syndrome.

Postpericardiotomy syndrome (PPS) is a frequent complication after cardiac surgery. In a recent study, elevated anticardiolipin antibody (ACLA) titres were observed in patients with PPS. The value of anti-heart muscle antibodies (AHA) for the diagnosis of PPS remains controversial. Therefore, a prospective double-blind study was performed to test the sensitivity and specificity of ACLA and AHA for the diagnosis of PPS. ACLA titres (ELISA) and AHA, elevated by immunofluorescence, the clinical course and routine laboratory parameters were assessed in 57 patients before and after elective cardiac surgery. ACLA increased and AHA first appeared after surgery in patients both with and without PPS. The sensitivities of a > or = 1.5-fold increase in IgM-ACLA titres, of a > or = 2-fold increase in IgG-ACLA titres and of the occurrence of AHA > or = 2+ for the diagnosis of PPS were 60%, 20% and 20%. The respective specificities were 43%, 79% and 85%. Thus, after cardiac surgery, increased ACLA titres and the occurrence of AHA, as assessed by immunofluorescence, may only contribute to the diagnosis of PPS to a limited extent.

Portraits of survival. A twenty-year follow-up of the children of Buffalo Creek.

This study is a follow-up of the children of Buffalo Creek "hollow" who survived the dam collapse and flood of 1972. It was conceived as a complement to the 1988 NIMH-funded follow-up investigation of the children of Buffalo Creek conducted by the University of Cincinnati Traumatic Stress Study Center. That 1988 study utilized standardized methodology to assess levels of psychopathology present among those who were children at the time of the 1972 flood. Among the original child subjects, results demonstrated that the rates of both posttraumatic stress disorder (PTSD) and levels of other psychopathology had sharply declined as the children moved to adulthood. Several questions remained unanswered: the long-term meaning which the flood had in the survivors' lives and its impact on their adaptation as they progressed through the subsequent stages of emotional development. For these reasons, we, as psychoanalytic investigators who had been members of the original clinical assessment team, planned an interview of child and adolescent survivors as a follow-up to our interviews in 1974 with a particular focus on meaning and adaptation.

Correlation of beta-2-microglobulin concentration changes to changes of distribution volume.

Plasma and ultrafiltrate beta-2-microglobulin (B2M) concentrations were determined during hemofiltration (HF) and hemodialysis (HD) in order to evaluate elimination kinetics of B2M. Calculations were done on the basis of plasma-water-concentrations (PWC). Elimination of B2M during HF follows first order kinetics (r = 0.97) and the volume of B2M distribution was calculated to be 17 +/- 2% of body weight. This reflects extracellular volume (ECV). Changes of ECV in HD were induced by weight loss and further provoked by fluid shifts from intra- to extracellular volume and vice versa induced by varying dialysate sodium concentration. These ECV changes were followed by determining inuline in plasma and total dialysate. Changes of B2M concentration correlate well to changes of ECV (r = 0.98). Thus intratreatment concentration changes of B2M in cuprophane dialysis reflect simultaneous changes of B2M distribution volume. This does not exclude the possibility of B2M generation stimulated by dialysis, but proving such effects in vivo will be difficult because of multiple variants, that must be controlled.

[The effect of ciprofloxacin on epinephrine and collagen induced thrombocyte aggregation in vitro on dialysis patients]. / Zum Einfluss von Ciprofloxacin auf die durch Epinephrine und Kollagen induzierte Thrombozytenaggregation in vitro bei Dialysepatienten.

In recent investigations it was found that ciprofloxacin (1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7 (1-piperazinyl)-3-fiquinoline-carboxylic acid, Ciprobay) in concentrations similar to maximal levels obtained in the serum of patients with normal renal function after application of therapeutic doses and 4- to 5fold such concentrations does not influence aggregation induced by epinephrine and collagen in platelet rich plasma of healthy subjects. Because in literature there are several reports about disturbances of platelet aggregation in patients with renal failure treated with antibiotics and because renal failure often is accompanied by defect platelet function the effect of ciprofloxacin on epinephrine and collagen induced aggregation was studied in platelet rich plasma of patients with chronic renal failure undergoing dialysis. Compared to platelets from patients with renal failure which had been incubated with saline instead of ciprofloxacin, patients platelets under the influence of ciprofloxacin did not show any significant differences. From this we conclude that the defect which may be present in platelets of patients with chronic renal failure is not further increased by ciprofloxacin.

Group meetings on an adolescent medical ward.

This report describes the development, functioning, content, and usefulness of patient group meetings on an adolescent medical ward. The meetings prove to be a useful technique in furthering the objectives of psychiatric consultation in such a setting. The meetings convinced the author that the threat to developing autonomy is the major focus of emotional conflict for the hospitalized adolescent. The meetings prove beneficial in helping the patients adjust to the experience of hospitalization. A diagnostic and educational function is also served.

Evaluating promulgated refinery effluent standards using artificial streams.

Two-week tests on an Artificial Refinery MIxture (ARM) were conducted on periphyton communities on glass slides in laboratory streams. ARM components, which are present in "typical" refinery effluents, approximate maximum allowable concentrations as promulgated by the 1977 U.S. Environmental Protection Agency (USEPA) guidelines for refinery effluents. ARM concentrations tested ranged from approximately 0.25 to 5 times full strength. The nontaxonomic structural parameters--ash-free dry weight, chlorophyll a, and ATP--indicated that ARM concentrations of 1 to 5X stimulated periphyton colonization rates. ARM concentrations of 0.25 to 5X caused a shift in dominant periphytic algae from diatoms in reference streams to green algae in dosed streams; this resulted in higher pH levels in reference streams, apparently related to photosynthetic activity. Changes in nontaxonomic structural parameters of slides precolonized with periphyton were not sensitive water quality indicators. Dry weight was not a useful biomass indicator due to high levels of suspended solids in ARM. The promulgated 1977 guidelines may be adequate to maintain nontaxonomic structural integrity of periphyton communities, while the 1983 guidelines appear to be adequate to maintain taxonomic integrity.

Secondary ion quadrupole mass spectrometer for depth profiling--design and performance evaluation.

A quadrupole-based secondary ion mass spectrometer designed for depth profiling is described which combines ultrahigh vacuum construction with high sputtering rate, detection sensitivity, depth resolution, mass spectral purity, and abundance sensitivity. Impurities such as B and Al implanted in Si can be profiled to levels below one part per million atomic (ppma), at a depth resolution equal to that obtained by commercial ion microprobes. The primary beam consists of 5-keV, mass-analyzed (40)Ar(+) ions, focused to about 70 microm in diameter. Its high current density (>25mA/cm(2)) permits adequate beam rastering and electronic signal-gating to optimize depth resolution. A secondary ion extraction lens and spherical energy filter are responsible for achieving abundance sensitivities of five to six orders of magnitude on the low mass side of a matrix peak. The ultrahigh vacuum environment of the sample dramatically reduces molecular peaks containing H, C, and O, allowing even hydrogen to be profiled to concentrations below 10 ppma. Because large amounts of data are generated by multi-element depth profiling, means for automated instrument control and data acquisition have been developed.

Somatic cell hybrids between human lymphoma lines. III. Surface markers.

Hybrids between two human lymphoma lines, Raji and Daudi (8A) and Raji BJAB (83) were examined for genetically determined and/or differentiation-related surface markers. HL-A B ce-l alloantigens, Fc and complement receptors, EBV receptors and beta2 microglobulin showed an autonomous ("co-dominant") expression in the hybrid. This is in contrast to most previous studies on other differentiation markers, involving as a rule crosses between cells of different lineages, where the differentiated pattern usually became "eclipsed" in the hybrid. Staining of activated complement and complement consumption tests showed intermediate or partially suppressed expression in the hybrids. This may be viewed in relation to the fact that these reactions do not merely depend on complement binding to the receptor, but also on subsequent activation and binding of the activated complement. A more complex interaction is also suggested for immunoglobulin production. Surface immunoglobulin showed a suppressive or intermediate pattern in both hybrids, whereas intracellular kappa chain production showed an amplification in the 83 hybrid. The beta2 microglobulin deficiency of the Daudi parent was corrected in the Raji/Daudi hybrid. Two new HL-A specificities,A10 and BW17, appeared on this hybrid which were not present on the parental lines. This suggests that the HL-A deficiency of the Daudi cell is due to its lack of beta2 microglobulin.

Inducibility of the Epstein-Barr virus (EBV) cycle and surface marker properties of EBV-negative lymphoma lines and their in vitro EBV-converted sublines.

Two EBV-negative lymphoma lines of human B-cell origin, BJAB and Ramos, were compared with altogether six of their in vitro EBV-converted, EBNA- and EBV-DNA-carrying sublines (four of Ramos and two of BJAB derivation). All converted lines closely resembled the parental line with regard to karyotype and HL-A and B antigen typing. Induction of EBV antigens (EA and VCA) by P3HR-1 virus superinfection was either similar in the converted and the negative lines, or somewhat increased in certain converted lines. These findings argue against a simple, virally determined repressor model and emphasize the role or cellular controls in restricting the EBV cycle in virus-carrying B-lymphocyte lines of human origin. IUdR inducibility varied in the different converted lines. There was a possible relationship between average number of EBV-genome equivalents per cell and inducibility. Converted sublines did not differ from the original negative lines with regard to surface immunoglobulin and Fc receptors. There was a dramatic increase in complement-consuming ability, however, following EBV conversion. Among the EBV-positive lines, there was a linear relationship between complement-consuming and EBV-receptor activity, the latter measured by a quantitative absorption test.

Blocking of HLA and B lymphocyte alloantigens with F (ab')2 fragments of rabbit antibodies.

F(ab')2 fragments of rabbit antibodies specific for human B lymphocytes will block human anti-B lymphocyte alloantibodies. F(ab')2 of anti-beta2m will block HLA alloantibodies. The F(ab')2 fragments can be used to improve the typing of B cell lines and certain leukemia cells which express both HLA and B lymphocyte alloantigens. Pretreatment of these cells with anti-beta2m F(ab')2 preparations allows the observation of B cell alloantigen reactions independently of HLA reactions. Similar use of rabbit anti-B cell F (ab')2 allows HLA reactions to be observed free from the "extra reactions" caused by B alloantibodies that are present in many HLA typing sera.

B lymphocyte alloantigen specificities present on cultured lymphoblastoid cell lines.

Thirty-three of 34 cultured human lymphoblastoid B cell lines have been shown to express four out of five polymorphic non-HLA specificities expressed by normal B lymphocytes. The specificities were detected by 32 alloantisera produced by absorption with pooled platelets to remove HLA activity and selected from over 400 pregnancy sera. One B group (B2) which was expressed by 23% of a panel of normal B lymphocytes was not found on any of the cultured lines tested. Four T cell lines tested and myeloid line (K562) did not react with any of the B cell alloantisera.