RESUMO
We present a novel concept to tackle the power exhaust challenge of a magnetically confined fusion plasma. It relies on the prior establishment of an X-point radiator that dissipates a large fraction of the exhaust power before it reaches the divertor targets. Despite the spatial proximity of the magnetic X point to the confinement region, this singularity is far away from the hot fusion plasma in magnetic coordinates and therefore allows the coexistence of a cold and dense plasma with a high potential to radiate. In the compact radiative divertor (CRD) the target plates are placed close to this magnetic X point. We here report on high performance experiments in the ASDEX Upgrade tokamak that indicate the feasibility of this concept. Despite the shallow (projected) field line incidence angles of the order of θ_{â¥}=0.2°, no hot spots were observed on the target surface monitored by an IR camera, even at a maximum heating power of P_{heat}=15 MW. And even with the X point located exactly on the target surface and without density or impurity feedback control, the discharge remains stable, the confinement good (H_{98,y2}=1), hot spots absent, and the divertor in a detached state. In addition to its technical simplicity, the CRD scales beneficially to reactor-scale plasmas that would benefit from an increased volume of the confined plasma, more space for breeding blankets, smaller poloidal field coil currents, and-potentially-an increased vertical stability.
RESUMO
This Letter presents the first observation on the interplay between nonlocal transport and neoclassical tearing modes (NTMs) during transient nonlocal heat transport events in the HL-2A tokamak. The nonlocality is triggered by edge cooling and large-scale, inward propagating avalanches. These lead to a locally enhanced pressure gradient at the q = 3/2 (or 2/1) rational surface and hence the onset of the NTM in relatively low ß plasmas (ßN < 1). The NTM, in return, regulates the nonlocal transport by truncation of avalanches by local sheared toroidal flows which develop near the magnetic island. These findings have direct implications for understanding the dynamic interaction between turbulence and large-scale mode structures in fusion plasmas.
RESUMO
Random peptide libraries and antigen-fragment libraries (also known as gene-fragment libraries) have been used to identify epitopes on protein antigens. These technologies promise to make significant contributions to diagnostic and vaccine development. Researchers in a number of labs have shown that phage selected from libraries with protective antibodies, raised against whole antigen, can be used as immunogens to stimulate antibody responses that bind native antigen and provide protection in vivo. Others have used the sera of patients with idiopathic diseases to screen libraries, and by this approach have identified candidate antigens involved in immune disease. These may prove useful for diagnosis and, possibly, in determining disease etiology.
Assuntos
Reações Antígeno-Anticorpo , Antígenos/química , Mapeamento de Epitopos/métodos , Biblioteca de Peptídeos , Kit de Reagentes para Diagnóstico , Vacinas , Anticorpos/sangue , Anticorpos/imunologia , Antígenos/imunologia , Bacteriófagos/genética , Portadores de Fármacos , LigantesRESUMO
The study involved two groups of patients aged 6-14 and 40-60 years, and identification of different conditions of gastric mucosa. The study has established a correlation between the nitrosation activity and acidity of gastric juice and the pathological condition of the gastric mucosa. Enhanced nitrosation activity was observed in samples with a pH under 4.0. That activity was at its lowest in cases of normal gastric mucosa, and at its peak--in high-acidity superficial and erosive gastritis. In cases of superficial gastritis with similar levels of acidity, the nitrosation activity of gastric juice for different amines in children was 2-4 times that in adults. The difference in nitrosation levels for different amines tended to diminish with the decrease in the basicity of the amine in question. A linear correlation was observed between the free-radical activity of gastric juice samples and nitrosation activity (correlation coefficient, k = 0.72).
Assuntos
Envelhecimento/metabolismo , Suco Gástrico/metabolismo , Mucosa Gástrica/metabolismo , Gastropatias/metabolismo , Adolescente , Adulto , Criança , Dimetilaminas/farmacocinética , Radicais Livres , Determinação da Acidez Gástrica , Humanos , Concentração de Íons de Hidrogênio , Pessoa de Meia-Idade , Nitrosação , Nitrito de Sódio/farmacocinéticaRESUMO
AIM: To compare cycleanine (Cyc), insularine (Insr), insulanoline (Insn) and verapamil (Ver) in modulation of multidrug resistance (MDR) in vitro. METHODS: The cytotoxic effect was determined by 3-[4, 5-dimethylthiazol-2-yl], 5-diphenyl tetarzolium bromide (MTT) assay. The intracellular doxorubincin (Dox) accumulation was assayed by spectrofluorometer. RESULTS: Cyc, Insr, Insn, and Ver showed significant activities in modulating Dox and vincristine resistances in acquired resistant MCF-7/Adr and KBv200 cell lines in a dose-dependent manner. Cyc, Insr, Insn, and Ver increased intracellular Dox accumulation in MCF-7/Adr cells. Cyc and Insr had greater activities than Ver in modulating MDR, while Insn had similar activity to that of Ver. CONCLUSION: MDR was modulated by Cyc, Insr, and Insn, due to the increase of intracellular Dox accumulation.
Assuntos
Anti-Hipertensivos/farmacologia , Isoquinolinas/farmacologia , Verapamil/farmacologia , Alcaloides/isolamento & purificação , Alcaloides/farmacologia , Anti-Hipertensivos/isolamento & purificação , Neoplasias da Mama/patologia , Doxorrubicina/metabolismo , Resistência a Múltiplos Medicamentos , Medicamentos de Ervas Chinesas/química , Humanos , Isoquinolinas/isolamento & purificação , Células KB/metabolismo , Células Tumorais Cultivadas/metabolismoRESUMO
Matrilin-2 is a member of von Willebrand factor A containing extracellular matrix proteins in which the cDNA-derived sequence shows similar domain organization to cartilage matrix protein/matrilin-1, but information on the protein structure is limited. Here we studied the oligomerization potential of a synthetic peptide NH2-ENLILFQNVANEEVRKLTQRLEEMTQRMEALENRLKYR-COOH corresponding to the C-terminal sequence of mouse matrilin-2. The central portion of this sequence shows a periodicity of hydrophobic residues occupying positions a and d of a heptad pattern (abcdefg)n, which is characteristic for alpha-helical coiled-coil proteins. Circular dichroism spectroscopy revealed a high alpha-helical content, and the shape of the spectra is indicative for a coiled-coil conformation. Chemical cross-linking and size exclusion chromatography suggest a homotrimeric configuration. Thermal denaturation in benign buffer shows a single cooperative transition with DeltaH0 = -375 kJ/mol. Melting temperatures Tm varied from 38 to 51 degreesC within a concentration range of 10 to 85 microM, which is about 35 degreesC lower than determined for a peptide corresponding to the C-terminal domain of matrilin-1. The data suggest that despite the low sequence identity within this region, matrilin-2 will form a homotrimer as matrilin-1 does.