HP-Xe to go: Storage and transportation of hyperpolarized (129)Xenon.

Recently the spin-lattice relaxation time T1 of hyperpolarized (HP)-(129)Xe was significantly improved by using uncoated and Rb-free storage vessels of GE180 glass. For these cells, a simple procedure was established to obtain reproducible wall relaxation times of about 18 h. Then the limiting relaxation mechanism in pure Xe is due to the coupling between the nuclear spins and the angular momentum of the Xe-Xe van-der-Waals-molecules. This mechanism can be significantly reduced by using different buffer gases of which CO2 was discovered to be the most efficient so far. From these values, it was estimated that for a 1:1 mixture of HP-Xe with CO2 a longitudinal relaxation time of about 7 h can be expected, sufficient to transport HP-Xe from a production to a remote application site. This prediction was verified for such a mixture at a total pressure of about 1 bar in a 10 cm glass cell showing a storage time of T1≈9 h (for T1(wall)=(34±9) h) which was transported inside a magnetic box over a distance of about 200 km by car.

New limit on Lorentz-invariance- and CPT-violating neutron spin interactions using a free-spin-precession He3-Xe129 comagnetometer.

We report on the search for a CPT- and Lorentz-invariance-violating coupling of the He3 and Xe129 nuclear spins (each largely determined by a valence neutron) to posited background tensor fields that permeate the Universe. Our experimental approach is to measure the free precession of nuclear spin polarized He3 and Xe129 atoms in a homogeneous magnetic guiding field of about 400 nT using LTC SQUIDs as low-noise magnetic flux detectors. As the laboratory reference frame rotates with respect to distant stars, we look for a sidereal modulation of the Larmor frequencies of the colocated spin samples. As a result we obtain an upper limit on the equatorial component of the background field interacting with the spin of the bound neutron b(⊥)(n)<8.4 × 10(-34) GeV (68% C.L.). Our result improves our previous limit (data measured in 2009) by a factor of 30 and the world's best limit by a factor of 4.

[Biomechanical modelling of the wrist joint]. / Biomechanische Modellierung der Handwurzel.

BACKGROUND: The hand represents one of the most complex joint mechanisms of the human body. The hand is also an important communication medium. The spectrum of today's hand injuries reaches from minor damage up to complex traumata with loss of several functional aspects. Enormous subsequent economic costs result. The therapeutic re-establishment of the equilibrium between maximum stress and the actual applied stress is the condition for a lifelong joint function. MATERIAL AND METHODS: A literature review about biomechanical wrist models was realised. The previous models found in the literature were systematically analysed as well as verifying their suitability for clinical use regarding pathological changes, therapy approaches and modelling/simulation approaches, respectively, of wrist injuries. RESULTS: The return of the wrist joint biomechanics to the normal condition is a key factor for a successful therapy. Furthermore, it is important for the re-establishment of an unimpaired joint function. Currently, there exist only simplified descriptions and models of the wrist joint, approximated by technical joints and furthermore, they are partially contradictory. Therefore, no uniform validated biomechanical wrist model exists as yet. CONCLUSION: Regarding the arising complex clinical problems, however, a valid biomechanical wrist joint model would be necessary as assistance, in order to improve the success of systematised therapies on the basis of computer-aided model-based planning and intervention.

Constraints on spin-dependent short-range interaction between nucleons.

We search for a spin-dependent P- and T-violating nucleon-nucleon interaction mediated by light pseudoscalar bosons such as axions or axionlike particles. We employ an ultrasensitive low-field magnetometer based on the detection of free precession of colocated 3He and 129Xe nuclear spins using SQUIDs as low-noise magnetic flux detectors. The precession frequency shift in the presence of an unpolarized mass was measured to determine the coupling of pseudoscalar particles to the spin of the bound neutron. For boson masses between 2 and 500 µeV (force ranges between 3×1(-4) m and 10(-1) m) we improved the laboratory upper bounds by up to 4 orders of magnitude.