290 research outputs found

    On particles in the Arctic stratosphere

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    Soon after the discovery of the Antarctic ozone hole it became clear that particles in the polar stratosphere had an infl uence on the destruction of the ozone layer. Two major types of particles, sulphate aerosols and Polar Stratospheric Clouds (PSCs), provide the surfaces where fast heterogeneous chemical reactions convert inactive halogen reservoir species into potentially ozone-destroying radicals. Lidar measurements have been used to classify the PSCs. Following the Mt. Pinatubo eruption in June 1991 it was found that the Arctic stratosphere was loaded with aerosols, and that aerosols observed with lidar and ozone observed with ozone sondes displayed a layered structure, and that the aerosol and ozone contents in the layers frequently appeared to be negatively correlated. The layered structure was probably due to modulation induced by the dynamics at the edge of the polar vortex. Lidar observations of the Mt. Pinatubo aerosols were in several cases accompanied by balloon-borne backscatter soundings, whereby backscatter measurements in three different wavelengths made it possible to obtain information about the particle sizes. An investigation of the infl uence of synoptic temperature histories on the physical properties of PSC particles has shown that most of the liquid type 1b particles were observed in the process of an ongoing, relatively fast, and continuous cooling from temperatures clearly above the nitric acid trihydrate condensation temperature (TNAT). On the other hand, it appeared that a relatively long period, with a duration of at least 1-2 days, at temperatures below TNAT provide the conditions which may lead to the production of solid type 1a PSCs

    Small Vessel Cerebrovascular Disease: The Past, Present, and Future

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    Brain infarction due to small vessel cerebrovascular disease (SVCD)—also known as small vessel infarct (SVI) or “lacunar” stroke—accounts for 20% to 25% of all ischemic strokes. Historically, SVIs have been associated with a favorable short-term prognosis. However, studies over the years have demonstrated that SVCD/SVI is perhaps a more complex and less benign phenomenon than generally presumed. The currently employed diagnostic and therapeutic strategies are based upon historical and contemporary perceptions of SVCD/SVI. What is discovered in the future will unmask the true countenance of SVCD/SVI and help furnish more accurate prognostication schemes and effective treatments for this condition. This paper is an overview of SVCD/SVI with respect to the discoveries of the past, what is known now, and what will the ongoing investigations evince in the future

    Use of Hypertonic Continuous Venovenous Hemodiafiltration to Control Intracranial Hypertension in an End-Stage Renal Disease Patient

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    Continuous venovenous hemodiafiltration (CVVHDF) using solutions designed to maintain hypernatremia is described in an end-stage renal disease (ESRD) patient with cerebral edema (CE) due to an intracerebral hemorrhage (ICH). Hypernatremia was readily achieved and maintained without complication. CVVHDF should be considered as an alternative treatment option in ESRD patients with cerebral edema who require hypertonic saline therapy

    Ruppeiner Geometry of RN Black Holes: Flat or Curved?

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    In some recent studies \cite{aman1, aman2, aman3}, Aman {\it et al.} used the Ruppeiner scalar as a measure of underlying interactions of Reissner-Nordstr\"{o}m black holes, indicating that it is a non-interacting statistical system for which classical thermodynamics could be used at any scale. Here, we show that if we use the complete set of thermodynamic variables, a non-flat state space will be produced. Furthermore, the Ruppeiner curvature diverges at extremal limits, as it would for other types of black holes.Comment: 9 page

    Effect of travelling fire on structural response of a generic steel fire protected moment resisting frame

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    To simulate a fire inside large compartments, there is a pioneering method called ‘traveling fire’. As steel structures are vulnerable to high temperatures, they are normally fireproofed by insulation materials appropriate for a specific duration of time. An investigation is performed here to examine the robustness of a generic fourstory moment-resisting steel structure, fireproofed to comply with the one-hour standard curve, when it is subjected to traveling fire. The results show that while no collapse occurs during the 12.5%, 50% and 100%, the structure collapses under the 25% fire size at 75 min. This seems to be in contradiction with traditional belief, where it is assumed that taking into consideration a larger-scale fire in a compartment would increase the safety margin. The investigation performed also underlines that the fireproofing of structures does not necessarily provide adequate resistance under traveling fires

    Immunization with Bivalent Flagellin Protects Mice against Fatal Pseudomonas aeruginosa Pneumonia

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    Pseudomonas aeruginosa lung infections present a major challenge to healthcare systems worldwide because they are commonly associated with high morbidity and mortality. Here, we demonstrate the protective efficacy of type a and b flagellins (bivalent flagellin) against acute fatal pneumonia in mice. Mice immunized intranasally with a bivalent flagellin vaccine were challenged by different flagellated strains of P. aeruginosa in an acute pneumonia model. Besides the protective effect of the vaccine, we further measured the host innate and cellular immunity responses. The immunized mice in our study were protected against both strains. Remarkably, active immunization with type a or b flagellin significantly improved survival of mice against heterologous strain compared to flagellin a or b antisera. We also showed that after an intranasal challenge by P. aeruginosa strain, neutrophils are recruited to the airways of vaccinated mice, and that the bivalent flagellin vaccine was proved to be protective by the generated CD4+IL-17+ Th17 cells. In conclusion, bivalent flagellin vaccine can confer protection against different strains of P. aeruginosa in an acute pneumonia mouse model by eliciting effective cellular and humoral immune responses, including increased IL-17 production and improved opsonophagocytic killing

    Construction of new 1D and 2D coordination polymers generated from rigid N,N′-bis(4-pyridylmethylene)-1,5-naphthalenediamine ligand:Syntheses, crystal structures and luminescence properties

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    Treatment of N,N′-bis(4-pyridylmethylene)-1,5-naphthalenediamine (L) with Pb(OAc)2/KBr, Cu(acac)2, and Cu(OAc)2 afforded three new coordination polymers [Pb(μ-L)(μ-Br)2]n (1), [Cu(μ-L)(acac)2]n (2), and [Cu2(μ-L)(μ-OAc)4]n (3). These coordination polymers have been structurally characterized by single crystal X-ray diffraction. Compound 1 has a 2D sheet structure in which the lead(II) centers are bridged by both L and bromide ligands. Compound 2 adopts a 1D neutral coordination chain and consists of bis(2,4-pentanedionato) copper(II) units connected by rigid bridging L ligands. The structure of compound 3 also adopts a 1D neutral coordination chain in which two copper centers are connected through four acetate groups to form a Cu(OAc)4Cu paddle-wheel-type cage between two bridging L ligands. The FT-IR spectra, thermal behavior and photoluminescence properties of these coordination polymers have also been investigated.</p

    Comparison of Melphalan Combined with Treosulfan or Busulfan as High-Dose Chemotherapy before Autologous Stem Cell Transplantation in AML.

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    (1) Background: High-dose chemotherapy (HDCT) before autologous stem cell transplantation (ASCT) in acute myeloid leukemia (AML) patients predominantly combines busulfan with cyclophosphamide or melphalan. Treosulfan compares favorably regarding lower inter-individual bioavailability and neurotoxicity, but so far, had not been studied before ASCT in AML. (2) Methods: This single-center study investigated AML patients undergoing ASCT in CR1 between November 2017 and September 2020. The first 16 patients received busulfan 16 mg/kg b.w. (days -5 to -2) and melphalan 140 mg/m2 (day -1) (BuMel). In a subsequent (TreoMel) cohort, 20 patients received treosulfan 14 g/m2 (days -4 to -2) and melphalan. Plasma concentrations of busulfan and treosulfan were determined by mass spectrometry. (3) Results: Neutrophil engraftment and platelet recovery were similar, and PFS and OS were comparable. In only the BuMel cohort, patients reported central nervous toxicities, including seizures (6%) and encephalopathy (12%). The mean AUC for busulfan was 1471.32 μM*min, and for treosulfan it was 836.79 mg/L*h, with ranges of 804.1-2082 μM*min and 454.2-1402 mg/L*h. The peak values for busulfan ranged between 880.19-1734 μg/L and for treosulfan between 194.3-489.25 mg/L. (4) Conclusions: TreoMel appears to be safe and effective for pre-ASCT treatment in AML patients. Due to considerable interindividual biovariability, pharmacologic monitoring may also be warranted for the use of treosulfan
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