Convenient access to bicyclic and tricyclic diazenes

Heating the tosylhydrazone of an omega-alkenyl ketone or aldehyde to reflux in toluene in the presence of K(2)CO(3) delivered the bicyclic diazene. Irradiation of the diazene converted it to the cyclopropane. This appears to be a generally useful method for the construction of substituted cyclopentanes and cyclohexanes.     

Natural Sphingomonas glycolipids vary greatly in their ability to activate natural killer T cells

Mouse natural killer T (NKT) cells expressing an invariant T cell antigen receptor (TCR) recognize glycosphingolipids (GSLs) from Sphingomonas bacteria. The synthetic antigens previously tested, however, were designed to closely resemble the potent synthetic agonist alpha-galactosyl ceramide (alphaGalCer), which contains a monosaccharide and a C18:0 sphingosine lipid. Some Sphingomonas bacteria, however, also have oligosaccharide-containing GSLs, and they normally synthesize several GSLs with different sphingosine chains including one with a cyclopropyl ring-containing C21:0 (C21cycl) sphingosine. Here we studied the stimulation of NKT cells with synthetic GSL antigens containing natural tetrasaccharide sugars, or the C21cycl sphingosine. Our results indicate that there is a great degree of variability in the antigenic potency of different natural Sphingomonas glycolipids, with the C21cycl sphingosine having intermediate potency and the oligosaccharide-containing antigens exhibiting limited or no stimulatory capacity.     

Preparation of ketones from nitriles and phosphoranes

The preparation of a ketone from a phosphorane and a nitrile is described. The workup conditions are mild, and the yields are high. The unreacted starting materials can easily be recovered.     

Preparation of the major urinary metabolite of (−)-prostaglandin E2

The best way to measure whole body production of the locally acting hormone prostaglandin E₂ (PGE₂) is to assess the accumulation of the major urinary metabolite, PGE₂U_M. A practical preparation of this delicate diacid is described. This synthetic PGE₂U_M will enable production of the antibodies that will be used to quantify this key metabolite.     

Ocean heat content and Earth's radiation imbalance

Earth's radiation imbalance is determined from ocean heat content data and compared with results of direct measurements. Distinct time intervals of alternating positive and negative values are found: 1960-mid-1970s (−0.15), mid-1970s-2000 (+0.15), 2001-present (−0.2 W/m²), and are consistent with prior reports. These climate shifts limit climate predictability.     

Faraday rotation of microwave fields in an electron cyclotronresonance plasma

An electron cyclotron resonance (ECR) plasma is created with 2.45-GHz linearly polarized microwaves, which propagate in the direction of the magnetic field. Measurements of the relative power and polarization angle versus z have been made within the first few centimeters of the quartz entry window. As the microwave electric field enters the plasma, it rotates while becoming elliptically polarized then circularly polarized. The rotation angle versus z and the component of the microwave field along the major axis of the polarization ellipse versus z are explained by cold plasma dispersion theory     

A data treatment method for detecting fluorescence anisotropy peaks in capillary electropherograms

A data treatment method is presented to detect fluorescence anisotropy (FA) peaks in capillary electrophoresis electropherograms. The data treatment method converts plots of fluorescence anisotropy vs. time that contain no peaks that are distinguishable from the noise of the anisotropy background into plots that show distinct fluorescence anisotropy peaks. The method was demonstrated using laser-induced fluorescence anisotropy data from individual Aβ (1–42) aggregates separated using capillary electrophoresis. Applying this data treatment method enabled the detection of anisotropy peaks for individual Aβ aggregate fluorescence peaks that were not observed prior to the data treatment method. The data treatment method is not specifically designed for Aβ aggregate analysis or capillary electrophoresis, and it should be applicable to other applications and other separation methods with FA detection.