Observation of high soft x-ray drive in large-scale hohlraums at the National Ignition Facility

The first soft x-ray radiation flux measurements from hohlraums using both a 96 and a 192 beam configuration at the National Ignition Facility have shown high x-ray conversion efficiencies of ～85%-90%. These experiments employed gold vacuum hohlraums, 6.4 mm long and 3.55 mm in diameter, heated with laser energies between 150-635 kJ. The hohlraums reached radiation temperatures of up to 340 eV. These hohlraums for the first time reached coronal plasma conditions sufficient for two-electron processes and coronal heat conduction to be important for determining the radiation drive.     

Enantioconvergent synthesis of (+)-aphanorphine via asymmetric Pd-catalyzed alkene carboamination

A concise asymmetric synthesis of (+)-aphanorphine has been achieved via a new enantioconvergent strategy. A racemic γ-aminoalkene derivative is transformed into a 1:1 mixture of enantiomerically enriched diastereomers using an asymmetric Pd-catalyzed carboamination. This mixture is then converted to an enantiomerically enriched protected aphanorphine derivative by a Friedel-Crafts reaction, which generates a quaternary all-carbon stereocenter. The natural product is obtained in three additional steps.     

Quantum Gravity and Phenomenological Philosophy

The central thesis of this paper is that contemporary theoretical physics is grounded in philosophical presuppositions that make it difficult to effectively address the problems of subject-object interaction and discontinuity inherent to quantum gravity. The core objectivist assumption implicit in relativity theory and quantum mechanics is uncovered and we see that, in string theory, this assumption leads into contradiction. To address this challenge, a new philosophical foundation is proposed based on the phenomenology of Maurice Merleau-Ponty and Martin Heidegger. Then, through the application of qualitative topology and hypernumbers, phenomenological ideas about space, time, and dimension are brought into focus so as to provide specific solutions to the problems of force-field generation and unification. The phenomenological string theory that results speaks to the inconclusiveness of conventional string theory and resolves its core contradiction. This article is based on my 2008 book, The Self-Evolving Cosmos, appearing in the Series on Knots and Everything of World Scientific Publishing Company.     

Electrodynamic metanuclei

A relativistic system of electrically charged fermions and oppositely charged massive scalars with no self-interactions, is argued to have a long-lived collective state with a net charge. The charge is residing near the surface of the spherically-symmetric state, while the interior consists of the condensed scalars, that are neutralized by the fermions. The metastability is achieved by competition of the negative pressure of the scalar condensate, against the positive pressure, mainly due to the fermions. We consider such metanuclei made of helium-4 nuclei and electrons, below nuclear but above atomic densities. Typical metanuclei represent charged balls of the atomic size, colossal mass, electric charge and excess energy. Unlike an ordinary nucleus, the charge of a metanucleus scales proportionately to its radius. The quantum mechanical decay through tunneling, and vacuum instability via pair-creation, are both suppressed for large values of the electric charge. Similar states could also be composed of other charged (pseudo)scalars, such as the pions, scalar supersymmetric partners, or in general, spin-0 states of new physics.     

An open-access, very-low-field MRI system for posture-dependent 3He human lung imaging

We describe the design and operation of an open-access, very-low-field, magnetic resonance imaging (MRI) system for in vivo hyperpolarized ³He imaging of the human lungs. This system permits the study of lung function in both horizontal and upright postures, a capability with important implications in pulmonary physiology and clinical medicine, including asthma and obesity. The imager uses a bi-planar B₀ coil design that produces an optimized 65 G (6.5 mT) magnetic field for ³He MRI at 210 kHz. Three sets of bi-planar coils produce the x, y, and z magnetic field gradients while providing a 79-cm inter-coil gap for the imaging subject. We use solenoidal Q-spoiled RF coils for operation at low frequencies, and are able to exploit insignificant sample loading to allow for pre-tuning/matching schemes and for accurate pre-calibration of flip angles. We obtain sufficient SNR to acquire 2D ³He images with up to 2.8 mm resolution, and present initial 2D and 3D ³He images of human lungs in both supine and upright orientations. ¹H MRI can also be performed for diagnostic and calibration reasons.     

Evidence of a Uranium-Paddlewheel Node in a Catecholate-Based Metal–Organic Framework

The interactions between uranium and non-innocent organic species are an essential component of fundamental uranium redox chemistry. However, they have seldom been explored in the context of multidimensional, porous materials. Uranium-based metal–organic frameworks (MOFs) offer a new angle to study these interactions, as these self-assembled species stabilize uranium species through immobilization by organic linkers within a crystalline framework, while potentially providing a method for adjusting metal oxidation state through coordination of non-innocent linkers. We report the synthesis of the MOF NU-1700 , assembled from U⁴⁺-paddlewheel nodes and catecholate-based linkers. We propose this highly unusual structure, which contains two U⁴⁺ ions in a paddlewheel built from four linkers—a first among uranium materials—as a result of extensive characterization via powder X-ray diffraction (PXRD), sorption, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA), in addition to density functional theory (DFT) calculations.