A super strong permanent magnet quadrupole (PMQ) was fabricated and tested. It has an integrated strength of 28.5T with overall length of 10 cm and a 7mm bore radius. Two drawbacks should be considered to this NdFeB based PMQ: the negative temperature coefficient of its field strength and its fixed strength. A thermal compensation material was added and tested to cure the first problem. The correct amount was determined to compensate the PMQ’s temperature coefficient. The required field variability can be obtained by slicing the magnet into pieces along the beamline direction and rotating these slices. But this technique may lead to movement of the magnetic center and introduction of a skew quadrupole component when the strength is varied. Materials with large temperature coefficients are widely used to compensate magnetic circuits in watt-hour meters, for instance magnetic flux is shunted by a compensation strip (high coefficient material) in parallel with the pole piece, such as shown in Figure 2. At low temperature, flux density between the pole pieces is reduced because of the shunt with high permeability. When the temperature rises, the field strength of the permanent magnet reduces, while the shunt flux is also reduced. As a result, the flux density between the pole pieces is kept constant.
Abstract Background Phosphoinositide-3 kinase (PI3K)/AKT signaling participates in cellular proliferation, survival and tumorigenesis. The activation of AKT signaling promotes the cellular reprogramming including generation of induced pluripotent stem cells (iPSCs) and dedifferentiation of primordial germ cells (PGCs). Previous studies suggested that AKT promotes reprogramming by activating proliferation and glycolysis. Here we report a line of evidence that supports the notion that AKT signaling is involved in TET-mediated DNA demethylation during iPSC induction. Methods AKT signaling was activated in mouse embryonic fibroblasts (MEFs) that were transduced with OCT4, SOX2 and KLF4. Multiomics analyses were conducted in this system to examine the effects of AKT activation on cells undergoing reprogramming. Results We revealed that cells undergoing reprogramming with artificially activated AKT exhibit enhanced anabolic glucose metabolism and accordingly increased level of cytosolic α-ketoglutarate (αKG), which is an essential cofactor for the enzymatic activity of the 5-methylcytosine (5mC) dioxygenase TET. Additionally, the level of TET is upregulated. Consistent with the upregulation of αKG production and TET, we observed a genome-wide increase in 5-hydroxymethylcytosine (5hmC), which is an intermediate in DNA demethylation. Moreover, the DNA methylation level of ES-cell super-enhancers of pluripotency-related genes is significantly decreased, leading to the upregulation of associated genes. Finally, the transduction of TET and the administration of cell-permeable αKG to somatic cells synergistically enhance cell reprogramming by Yamanaka factors. Conclusion These results suggest the possibility that the activation of AKT during somatic cell reprogramming promotes epigenetic reprogramming through the hyperactivation of TET at the transcriptional and catalytic levels.
The effect of captopril and a mixture of captopril and copper on natural killer (NK) activity of normal human peripheral blood mononuclear cells (PBMC) was examined. Preincubation of PBMC with captopril alone did not affect their NK activity at concentrations of 5-50 micrograms/ml. However, in the presence of copper sulfate, captopril inhibited the NK activity in a dose-response fashion. Similar inhibition was observed when adherent depleted fraction was treated with captopril and copper. In the time course study, significant inhibition of NK activity by captopril and copper was already observed at 3 hr preincubation. The inhibition of NK activity by captopril and copper was completely abolished by the addition of catalase, but not by superoxide dismutase, interleukin-2, or indomethacin. Preincubation of PBMC with captopril and copper for 18 hr decreased its viability. This decrease was also reversed in the presence of catalase. These results suggest that immunosuppression by captopril in the presence of copper was mediated by hydrogen peroxide.
A protocol for the direct analysis of the phospholipid composition in the whole body of adult soil nematode, Caenorhabditis elegans (C. elegans), was developed, which combined freeze-cracking of the exoskeletal cuticle and matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS). Biomolecules in the m/z range from 700 to 900 were more effectively detected in the freeze-cracked than from simple frozen adult nematode bodies. Different distribution of biomolecules was observed in a nematode body when the matrix was applied with a sublimation deposition method. The whole-body IMS technique was applied on genetically deficient mutant C. elegans to combine whole-body lipidomics and genetics, by comparing the fatty acid compositions, especially of the phosphatidylcholine (PC) species, between the wild-type and fat-1 mutants, which lack the gene encoding an n-3 fatty acid desaturase. A significant reduction of PC(20:5/20:5) and PC(20:4/20:5) and a marked increase of PC(20:4/20:4), PC(20:3/20:4), and PC(20:3/20:3) were detected in the fat-1 mutants in positive ion mode. In addition, phospholipid compositions other than PCs were analyzed in negative ion mode. A loss of a possible phosphatidylinositol (PI) with 18:0/20:5 and a compensative accumulation of putative PI(18:0/20:4) were detected in the fat-1 mutants. In conclusion, the whole-body MALDI-IMS technique is useful for the profiling of multiple biomolecules in C. elegans in both intra- and inter-individual levels.
The authors have been developing very strong permanent magnets. In the past, our magnets could generate greater than 5 Tesla dipole fields. We are now in a process of reaching much higher fields. The present paper is devoted to describing magnetic design developments in order to obtain super strong magnetic fields (of order of several Tesla magnitudes) with permanent magnets with a working gap sized large enough for practical applications.
