265 research outputs found
Generation of Catalytic Films of Zeolite Y and ZSM-5 on FeCrAlloy Metal
This work details the generation of thin films of structured zeolite catalysts (ZSM–5 and Y) onto the surface of a metal substrate (FeCrAlloy) using in-situ hydrothermal synthesis. In addition, the zeolite Y is post-synthetically modified by acidified ammonium ion exchange to generate US-Y. Finally the catalytic activity of the structured ZSM-5 catalyst films (Si/Al = 11, thickness 146 µm) and structured US–Y catalyst film (Si/Al = 8, thickness 23µm) were compared with the pelleted powder form of ZSM–5 and USY catalysts of similar Si/Al ratios. The structured catalyst films have been characterised using a range of techniques, including X-ray diffraction (XRD), Electron microscopy (SEM), Energy Dispersive X–ray analysis (EDX) and Thermogravimetric Analysis (TGA). The transition from oxide-on-alloy wires to hydrothermally synthesised uniformly zeolite coated surfaces was followed using SEM and XRD. In addition, the robustness of the prepared coating was confirmed by subjecting these to thermal cycling (ambient to 550°C). The cracking of n–heptane over the pellets and structured catalysts for both ZSM–5 and Y zeolite showed very similar product selectivities for similar amounts of catalyst with an apparent activation energy of around 60 kJ mol-1. This paper demonstrates that structured catalysts can be manufactured with excellent zeolite adherence and when suitably activated/modified give comparable cracking results to the pelleted powder forms. These structured catalysts will improve temperature distribution in highly exothermic and endothermic catalysed processes
Antibacterial Effect of Silver Nanoparticles Prepared from Sophora flavescens Root Aqueous Extracts against Multidrug-resistance Pseudomonas aeruginosa and Staphylococcus aureus
Green synthesis of metal nanoparticles (NPs) from plant extracts has attracted significant interest in modern medicine. Therefore, this study prepared an aqueous extract of Sophora flavescens roots, which are used in folk medicine to treat several diseases, including bacterial infections. In addition, silver NPs (AgNPs) were synthesized from root extract using the green synthesis method. The NPs were diagnosed using modern methods. Additionally, the antibacterial activity of the root aqueous extract and AgNPs aqueous preparation (at concentrations of 7% and 9%, respectively) was examined against selected isolates of multidrug-resistant Pseudomonas aeruginosa and Staphylococcus aureus. The results indicated that both the plant extract and NP preparations inhibited pathogenic bacterial isolates
Intrinsic Terahertz Plasmons and Magnetoplasmons in Large Scale Monolayer Graphene
We show that in graphene epitaxially grown on SiC the Drude absorption is
transformed into a strong terahertz plasmonic peak due to natural nanoscale
inhomogeneities, such as substrate terraces and wrinkles. The excitation of the
plasmon modifies dramatically the magneto-optical response and in particular
the Faraday rotation. This makes graphene a unique playground for
plasmon-controlled magneto-optical phenomena thanks to a cyclotron mass 2
orders of magnitude smaller than in conventional plasmonic materials such as
noble metals.Comment: to appear in Nano Letter
The low-mass initial mass function of the field population in the Large Magellanic Cloud with Hubble Space Telescope WFPC2 Observations
We present V- and I-equivalent HST/WFPC2 stellar photometry of an area in the
Large Magellanic Cloud (LMC), located on the western edge of the bar of the
galaxy, which accounts for the general background field of its inner disk. The
WFPC2 observations reach magnitudes as faint as V=25 mag, and the large sample
of more than 80,000 stars allows us to determine in detail the Present-Day Mass
Function (PDMF) of the detected main-sequence stars, which is identical to the
Initial Mass Function (IMF) for masses M <~ 1 M_solar. The low-mass
main-sequence mass function of the LMC field is found not to have a uniform
slope throughout the observed mass range, i.e. the slope does not follow a
single power law. This slope changes at about 1 M_solar to become more shallow
for stars with smaller masses down to the lowest observed mass of ~ 0.7
M_solar, giving clear indications of flattening for even smaller masses. We
verified statistically that for stars with M <~ 1 M_solar the IMF has a slope
Gamma around -2, with an indicative slope Gamma =~ -1.4 for 0.7 <~ M/M_solar <~
0.9, while for more massive stars the main-sequence mass function becomes much
steeper with Gamma =~ -5. The main-sequence luminosity function (LF) of the
observed field is in very good agreement with the Galactic LF as it was
previously found. Taking into account several assumptions concerning
evolutionary effects, which should have changed through time the stellar
content of the observed field, we reconstruct qualitatively its IMF for the
whole observed mass range (0.7 <~ M/M_solar <~ 2.3) and we find that the number
of observed evolved stars is not large enough to have affected significantly
the form of the IMF, which thus is found almost identical to the observed PDMF.Comment: 16 pages in ApJ Journal format, 7 figures, Submitted to ApJ. The size
of the postscript files of the images has been reduced because of disk space
limitation
High intensity neutrino oscillation facilities in Europe
The EUROnu project has studied three possible options for future, high intensity neutrino oscillation facilities in Europe. The first is a Super Beam, in which the neutrinos come from the decay of pions created by bombarding targets with a 4 MW proton beam from the CERN High Power Superconducting Proton Linac. The far detector for this facility is the 500 kt MEMPHYS water Cherenkov, located in the Fréjus tunnel. The second facility is the Neutrino Factory, in which the neutrinos come from the decay of μ+ and μ− beams in a storage ring. The far detector in this case is a 100 kt magnetized iron neutrino detector at a baseline of 2000 km. The third option is a Beta Beam, in which the neutrinos come from the decay of beta emitting isotopes, in particular He6 and Ne18, also stored in a ring. The far detector is also the MEMPHYS detector in the Fréjus tunnel. EUROnu has undertaken conceptual designs of these facilities and studied the performance of the detectors. Based on this, it has determined the physics reach of each facility, in particular for the measurement of CP violation in the lepton sector, and estimated the cost of construction. These have demonstrated that the best facility to build is the Neutrino Factory. However, if a powerful proton driver is constructed for another purpose or if the MEMPHYS detector is built for astroparticle physics, the Super Beam also becomes very attractive
Relationships between TGFβ Proteins and Oxygen Concentrations Inside the First Trimester Human Gestational Sac
In early pregnancy, the O2 gradient between the maternal circulation and the gestational sac tissues modulates trophoblast biological functions. The aim was to evaluate if placental partial pressure of oxygen (PaO2) modulates in vivo synthesis of specific placental proteins inside the first trimester gestational sac. Matched samples of peripheral venous blood, blood from the placental bed (PB), coelomic fluid (CF) and placental tissue were obtained in 37 normal pregnancies at 6–12 weeks gestation. PaO2 was measured in PB and CF using an IRMA blood gas monitor. Inhibin A, activin A, sEng, PlGF, sFlt-1 and free VEGF concentrations were measured in all samples. HSP 70 was measured in placental extracts. ANOVA showed ∼60% increase in PB PaO2 (P = 0.02) between after 10 weeks gestation. Unpaired Student's T-test between two groups (6–9 weeks vs 9–12 weeks) shows a significant increase in MS Activin A (P = 0.001), CF activin A (P<0.001), MS P1GF (P = 0.001), CF PlGF (P<0.001), MS sFLT-1 (P = 0.03), CF sFLT-1 (P = 0.01), HSP 70 in placental extracts (P = 0.04) and a significant decrease in PB inhibin A levels (P<0.001) and PB sFLT-1 (P = 0.02) . Multiple correlation analysis showed a significant negative correlation between PB inhibin A levels and gestation (r = −0.45, P<0.05) and PB PaO2 (r = −0.5, P = 0.008) and also between sFLT-1 and PB PaO2 (P = 0.03). There was a positive correlation (P<0.01) between PlGF, sEng and VEGF levels in the placental extracts. Our results indicate a direct relationship in the early intrauterine PaO2 in vivo and inhibin A and sFLT-1 concentrations confirming our hypothesis that specific placental proteins are regulated by intrauterine O2 tension
Plasma irisin is elevated in type 2 diabetes and is associated with increased E-selectin levels
BACKGROUND: Irisin is a hormone released mainly from skeletal muscle after exercise which increases adipose tissue energy expenditure. Adipocytes can also release irisin after exercise, acting as a local adipokine to induce white adipose tissue to take on a brown adipose tissue-like phenotype, suggesting that irisin and its receptor may represent a novel molecular target for the treatment of obesity and obesity-related diabetes. Previous reports provide conflicting evidence regarding circulating irisin levels in patients with type 2 diabetes (T2DM). METHODS: This study investigated plasma irisin concentrations in 79 T2DM individuals, assessing potential associations with measures of segmental body composition, markers of endothelial dysfunction and peripheral blood mononuclear cell telomere length (TL). RESULTS: Resting, overnight-fasted plasma irisin levels were significantly higher in this group of T2DM patients compared with levels we previously reported in healthy volunteers (p < 0.001). Moreover, plasma irisin displayed a positive correlation with body mass index (p = 0.04), body fat percentage (p = 0.03), HbA1c (p = 0.03) and soluble E-selectin (p < 0.001). A significant negative association was observed between plasma irisin and visceral adiposity (p = 0.006) in T2DM patients. Multiple regression analysis revealed that circulating soluble E-selectin levels could be predicted by plasma irisin (p = 0.004). Additionally, cultured human umbilical vein endothelial cells (HUVEC) exposed to 200 ng/ml irisin for 4 h showed a significant fourfold increase in E-selectin and 2.5-fold increase in ICAM-1 gene expression (p = 0.001 and p = 0.015 respectively), and there was a 1.8-fold increase in soluble E-selectin in conditioned media (p < 0.05). CONCLUSION: These data suggest that elevated plasma irisin in T2DM is associated with indices of adiposity, and that irisin may be involved in pro-atherogenic endothelial disturbances that accompany obesity and T2DM. Accordingly, irisin may constitute a potentially novel therapeutic opportunity in the field of obesity and cardiovascular diabetology
Cancer Treatment and Bone Health
Considerable advances in oncology over recent decades have led to improved survival, while raising concerns about long-term consequences of anticancer treatments. In patients with breast or prostate malignancies, bone health is a major issue due to the high risk of bone metastases and the frequent prolonged use of hormone therapies that alter physiological bone turnover, leading to increased fracture risk. Thus, the onset of cancer treatment-induced bone loss (CTIBL) should be considered by clinicians and recent guidelines should be routinely applied to these patients. In particular, baseline and periodic follow-up evaluations of bone health parameters enable the identification of patients at high risk of osteoporosis and fractures, which can be prevented by the use of bone-targeting agents (BTAs), calcium and vitamin D supplementation and modifications of lifestyle. This review will focus upon the pathophysiology of breast and prostate cancer treatment-induced bone loss and the most recent evidence about effective preventive and therapeutic strategies
Schizophrenia risk conferred by rare protein-truncating variants is conserved across diverse human populations
Schizophrenia (SCZ) is a chronic mental illness and among the most debilitating conditions encountered in medical practice. A recent landmark SCZ study of the protein-coding regions of the genome identified a causal role for ten genes and a concentration of rare variant signals in evolutionarily constrained genes1. This recent study—and most other large-scale human genetics studies—was mainly composed of individuals of European (EUR) ancestry, and the generalizability of the findings in non-EUR populations remains unclear. To address this gap, we designed a custom sequencing panel of 161 genes selected based on the current knowledge of SCZ genetics and sequenced a new cohort of 11,580 SCZ cases and 10,555 controls of diverse ancestries. Replicating earlier work, we found that cases carried a significantly higher burden of rare protein-truncating variants (PTVs) among evolutionarily constrained genes (odds ratio = 1.48; P = 5.4 × 10−6). In meta-analyses with existing datasets totaling up to 35,828 cases and 107,877 controls, this excess burden was largely consistent across five ancestral populations. Two genes (SRRM2 and AKAP11) were newly implicated as SCZ risk genes, and one gene (PCLO) was identified as shared by individuals with SCZ and those with autism. Overall, our results lend robust support to the rare allelic spectrum of the genetic architecture of SCZ being conserved across diverse human populations
Melanocortin-1 Receptor, Skin Cancer and Phenotypic Characteristics (M-SKIP) Project: Study Design and Methods for Pooling Results of Genetic Epidemiological Studies
Background: For complex diseases like cancer, pooled-analysis of individual data represents a powerful tool to investigate the joint contribution of genetic, phenotypic and environmental factors to the development of a disease. Pooled-analysis of epidemiological studies has many advantages over meta-analysis, and preliminary results may be obtained faster and with lower costs than with prospective consortia. Design and methods: Based on our experience with the study design of the Melanocortin-1 receptor (MC1R) gene, SKin cancer and Phenotypic characteristics (M-SKIP) project, we describe the most important steps in planning and conducting a pooled-analysis of genetic epidemiological studies. We then present the statistical analysis plan that we are going to apply, giving particular attention to methods of analysis recently proposed to account for between-study heterogeneity and to explore the joint contribution of genetic, phenotypic and environmental factors in the development of a disease. Within the M-SKIP project, data on 10,959 skin cancer cases and 14,785 controls from 31 international investigators were checked for quality and recoded for standardization. We first proposed to fit the aggregated data with random-effects logistic regression models. However, for the M-SKIP project, a two-stage analysis will be preferred to overcome the problem regarding the availability of different study covariates. The joint contribution of MC1R variants and phenotypic characteristics to skin cancer development will be studied via logic regression modeling. Discussion: Methodological guidelines to correctly design and conduct pooled-analyses are needed to facilitate application of such methods, thus providing a better summary of the actual findings on specific fields
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