309 research outputs found

    Development of Strength in Cements

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    Agreement No. 4 (PL 480)This report is divided into two parts: Portland and Sorel Cements. Portland Cement: The production of doped belite (dicalcium silicate) clinkers can be a prospective way of saving energy in cement production. Barium sulfate (BaSO sub-4), calcium tribasic phosphate (Ca sub-5 (PO sub-4) sub-3 (OH), and vanadium oxide (V sub-2 0 sub-5) stabilize Beta-, alpha' and alpha modifications of belite (C sub-2 S). The aplha' modification shows better strength development than the Beta-C sub-2 S. Strength develops more slowly in Ca sub-5 (PO sub-4) sub-3 OH than in BaSO sub-4, stabilized belites. Also, belite clinkers doped with BaSO sub-4 attain greater strength than belites without BaSO sub-4. Sorel Cement: The reaction products are dependent on the proportion of reactants (MgO, MgC1 sub-2, and H sub-2 O) and on MgO activity. Hardened cements achieve the best strength development and stability when phase 5 (5Mg (OH) sub-2 .MgC1 sub-2 .(H sub-2 O) is the main reaction product. Phosphate addition, especially soluble phosphates, which are more effective, improves the cement's resistance to the effects of water

    Occult Cushing\u27s Syndrome Presenting with Osteoporosis

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    Osteoporosis is a frequent complication both of endogenous hypercortisolism and of long-term treatment with corticosteroids, but only rarely is it the major clinical feature with the more characteristic features absent or minimally present. In the two patients presented, hypercortisolism was uncovered only during routine evaluation of osteoporosis. This presentation is probably due to slow progression of the disease and is often associated with so-called black adenoma of the adrenal gland. Secondary causes should be sought in all patients with seemingly senile or postmenopausal osteoporosis

    Cell Surface Expression and Function of the Macromolecular C1 Complex on the Surface of Human Monocytes

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    The synthesis of the subunits of the C1 complex (C1q, C1s, C1r), and its regulator C1 inhibitor (C1-Inh) by human monocytes has been previously established. However, surface expression of these molecules by monocytes has not been shown. Using flow cytometry and antigen-capture enzyme-linked immunosorbent assay, we show here for the first time that, in addition to C1q, peripheral blood monocytes, and the monocyte-derived U937 cells express C1s and C1r, as well as Factor B and C1-Inh on their surface. C1s and C1r immunoprecipitated with C1q, suggesting that at least some of the C1q on these cells is part of the C1 complex. Furthermore, the C1 complex on U937 cells was able to trigger complement activation via the classical pathway. The presence of C1-Inh may ensure that an unwarranted autoactivation of the C1 complex does not take place. Since C1-Inh closely monitors the activation of the C1 complex in a sterile or infectious inflammatory environment, further elucidation of the role of C1 complex is crucial to dissect its function in monocyte, dendritic cell, and T cell activities, and its implications in host defense and tolerance

    Estudio del uso de Eversa® transform como catalizador en la transesterificación de aceite de girasol usado

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    En los últimos años, el estudio sobre la producción de biodiesel de segunda generación ha ganado interés, especialmente las investigaciones acerca del uso de biocatalizadores. En esta contribución se presenta el estudio sobre la aplicación del biocatalizador comercial Eversa® Transform en reacciones de transesterificación de aceite de girasol usado en cocción

    Radially extended kinematics and stellar populations of the massive ellipticals NGC1600, NGC4125 and NGC7619. Constraints on the outer dark halo density profile

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    We present high quality long slit spectra along the major and minor axes out to 1.5-2 Re (14-22 kpc) of three bright elliptical galaxies (NGC1600, NGC4125, NGC7619) obtained at the Hobby-Eberly Telescope (HET). We derive stellar kinematic profiles and Lick/IDS indices (Hbeta, Mgb, Fe5015, Fe5270, Fe5335, Fe5406). Moreover, for NGC4125 we derive gas kinematics and emission line strengths. We model the absorption line strengths using Simple Stellar Populations models that take into account the variation of [\alpha/Fe] and derive ages, total metallicity and element abundances. Overall, we find that the three galaxies have old and [\alpha/Fe] overabundant stellar populations with no significant gradients. The metallicity is supersolar at the center with a strong negative radial gradient. For NGC4125, several pieces of evidence point to a recent dissipational merger event. We calculate the broad band color profiles with the help of SSP models. All of the colors show sharp peaks at the center of the galaxies, mainly caused by the metallicity gradients, and agree well with the measured colors. Using the Schwarzschild's axisymmetric orbit superposition technique, we model the stellar kinematics to constrain the dark halos of the galaxies. We use the tight correlation between the Mgb strength and local escape velocity to set limits on the extent of the halos by testing different halo sizes. Logarithmic halos - cut at 60 kpc -minimize the overall scatter of the Mgb-Vesc relation. Larger cutoff radii are found if the dark matter density profile is decreasing more steeply at large radii.Comment: Accepted for publication in Astronomy and Astrophysic

    Relating basic properties of bright early-type dwarf galaxies to their location in Abell 901/902

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    We present a study of the population of bright early-type dwarf galaxies in the multiple-cluster system Abell 901/902. We use data from the STAGES survey and COMBO-17 to investigate the relation between the color and structural properties of the dwarfs and their location in the cluster. The definition of the dwarf sample is based on the central surface brightness and includes galaxies in the luminosity range -16 >= M_B >~-19 mag. Using a fit to the color magnitude relation of the dwarfs, our sample is divided into a red and blue subsample. We find a color-density relation in the projected radial distribution of the dwarf sample: at the same luminosity dwarfs with redder colors are located closer to the cluster centers than their bluer counterparts. Furthermore, the redder dwarfs are on average more compact and rounder than the bluer dwarfs. These findings are consistent with theoretical expectations assuming that bright early-type dwarfs are the remnants of transformed late-type disk galaxies involving processes such as ram pressure stripping and galaxy harassment. This indicates that a considerable fraction of dwarf elliptical galaxies in clusters are the results of transformation processes related to interactions with their host cluster.Comment: 12 pages, 8 figures, accepted for publication in A&A, typo corrected in abstrac

    Peak bone mineral density in Vietnamese women

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    While the prevalence of osteoporosis and risk factors for low bone mineral density (BMD) has been well documented in Caucasian populations, there is a lack of data from Asia. This work was designed to clarify to what extent osteoporosis could be regarded as a major public health problem in Vietnam. Furthermore, to elucidate the prevalence of certain risk factors, such as vitamin D deficiency and other determinants of bone mass as a basis to indentify high-risk individuals among the Vietnamese women and men. The clinical studies were designed as cross-sectional investigations using a multistage sampling scheme. Within the setting of northern Vietnam (latitude 21°N), districts were selected to represent urban and rural areas. In total 612 healthy women and 222 men aged 13-83 years were investigated. BMD was measured at the lumbar spine, femoral neck and total hip in all qualified subjects with dual energy X-ray absortiometry. Serum concentrations of 25(OH)D, parathyroid hormone, estrogen and testosterone were quantified by electrochemiluminescence immunoassay. Data on clinical history and lifestyle were collected by individual face-to-face interviews. Reference values for peak BMD were defined. These data allowed the calculation of T-scores and thus for the first time, an accurate identification of osteoporosis in a Vietnamese population. As determined at the femoral neck, the prevalence of osteoporosis was 17-23% in women and 9% in men. The results clearly suggest that osteoporosis is an important public health problem. Postmenopausal women living in urban areas experienced osteoporosis more than rural residents. Serum levels of 25(OH)D and estrogen were significantly associated with bone mass in both women and men. The prevalence of vitamin D deficiency (<20 ng/mL) was very high, 30% in women and 16% in men. An experimental study on the isoflavone content of different soymilk preparations was performed by HPLC (high pressure liquid chromatography). Values of isoflavones were very low, around 60-80 mg/L, and there were only 10-20% of bioactive aglycones. This is far below the reported threshold levels to exert significant effects on bone. In the future these data will be useful as a valuable reference base to diagnose osteoporosis and for the clinical management of its consequences. The high prevalence of vitamin D deficiency should raise the awareness of potentially important health issues such as osteoporosis but also about other serious diseases within the Vietnamese society

    Anti-chemokine antibodies after SARS-CoV-2 infection correlate with favorable disease course.

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    Infection by SARS-CoV-2 leads to diverse symptoms, which can persist for months. While antiviral antibodies are protective, those targeting interferons and other immune factors are associated with adverse COVID-19 outcomes. Instead, we discovered that antibodies against specific chemokines are omnipresent after COVID-19, associated with favorable disease, and predictive of lack of long COVID symptoms at one year post infection. Anti-chemokine antibodies are present also in HIV-1 and autoimmune disorders, but they target different chemokines than those in COVID-19. Finally, monoclonal antibodies derived from COVID- 19 convalescents that bind to the chemokine N-loop impair cell migration. Given the role of chemokines in orchestrating immune cell trafficking, naturally arising anti-chemokine antibodies associated with favorable COVID-19 may be beneficial by modulating the inflammatory response and thus bear therapeutic potential. One-Sentence Summary Naturally arising anti-chemokine antibodies associate with favorable COVID-19 and are predictive of lack of long COVID
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