A comprehensive characterization of the T-cell antigen receptor complex composition by microcapillary liquid chromatography-tandem mass spectrometry

It has become apparent that many intracellular signaling processes involve the dynamic reorganization of cellular proteins into complex signaling assemblies that have a specific subunit composition, function, and subcellular location. Since the elements of such assemblies interact physically, multiprotein signaling complexes can be isolated and analyzed. Recent technical advances in highly sensitive protein identification by electrospray-tandem mass spectrometry have dramatically increased the sensitivity with which such analyses can be performed. The T-cell antigen receptor (TCR) is an oligomeric transmembrane protein complex that is essential to T-cell recognition and function. The extracellular protein domains are responsible for ligand binding while intracellular domains generate and transduce signals in response to specific receptor-ligand interactions. We used microbore capillary chromatography-tandem mass spectrometry to investigate the composition of the TCR protein complex isolated from resting and activated cells of the murine T-cell line CD11.3. We identified all the previously known subunits of the TCR/CD3 complex as well as proteins previously not known to associate with the TCR. The catalytic activities of some of these proteins could potentially be used to interfere pharmacologically with TCR signaling.     

Search for direct CP violation in nonleptonic decays of charged Xi and lambda hyperons

A search for direct CP violation in the nonleptonic decays of hyperons has been performed. In comparing the product of the decay parameters, alpha(Xi)alpha(Lambda), in terms of an asymmetry parameter, A(XiLambda), between hyperons and antihyperons in the charged Xi-->Lambdapi and Lambda-->ppi decay sequence, we found no evidence of direct CP violation. The parameter A(XiLambda) was measured to be 0.012+/-0.014.     

Deformations and dilations of chaotic billiards: dissipation rate, and quasiorthogonality of the boundary wave functions

We consider chaotic billiards in d dimensions, and study the matrix elements M(nm) corresponding to general deformations of the boundary. We analyze the dependence of |M(nm)|(2) on omega = (E(n)-E(m))/Planck's over 2pi using semiclassical considerations. This relates to an estimate of the energy dissipation rate when the deformation is periodic at frequency omega. We show that, for dilations and translations of the boundary, |M(nm)|(2) vanishes like omega(4) as omega-->0, for rotations such as omega(2), whereas for generic deformations it goes to a constant. Such special cases lead to quasiorthogonality of the eigenstates on the boundary.     

Vinylcarbonates and vinylcarbamates: Biocompatible monomers for radical photopolymerization

The last decade has seen a remarkable interest in the use of biocompatible and biodegradable polymers as scaffolds for tissue engineering. The fabrication of 3D scaffolds by lithography‐based additive manufacturing technology (AMT) represents an appealing approach. As poly(lactic acid), the state of the art biocompatible and biodegradable material, cannot be processed by these photopolymerization‐based techniques, it has so far been necessary to use selected (meth)acrylates. By developing new photopolymers based on vinyl carbonates and vinyl carbamates as a reactive group we have been able to avoid most of the disadvantages of classical (meth)acrylate‐based photopolymers. The new generation of biocompatible monomers show low cytotoxicity, have good storage stability, and are sufficiently photoreactive to be structured by lithography based AMT. The mechanical properties and rates of degradation of the polymers can be easily tuned over a broad range. Degradation results in the formation of nonacidic and nontoxic degradation products of low molecular weight that can be easily transported within the human body. Initial in vivo tests showed significant osseointegration of the 3D cellular scaffolds and no signs of implant rejection. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Influence of Process Parameters on the Reaction Kinetics of the Chromium‐Catalyzed Trimerization of Ethylene

In this paper we report the results of an extensive experimental kinetic study carried out on the novel ethylene trimerization catalyst system, comprising the chromium source [CrCl₃(thf)₃] (thf=tetrahydrofuran), a Ph₂P‐N(iPr)‐P(Ph)‐N(iPr)H (PNPNH) ligand (Ph=phenyl, iPr=isopropyl), and triethylaluminum (AlEt₃) as activator. It could be shown that the initial activity shows a first‐order dependency on the ethylene concentration. Also, a first‐order dependency was found for the catalyst concentration. The initial activity follows a typical Arrhenius behavior with an experimentally determined activation energy of 52.6 kJ mol^?1. At elevated temperatures (ca. 80 °C), a significant deactivation was observed, which can be tentatively traced back to a ligand rearrangement in the presence of AlEt₃. After a fast initial phase, a pronounced ‘kink’ in the ethylene‐uptake curve is observed, followed by a slow, almost linear, further increase of the total ethylene consumption. The catalyst composition, in particular the ligand/chromium and the cocatalyst/chromium molar ratio, has a strong impact on the catalytic performance of the trimerization of ethylene.     

Fundamental Problems in the Unification of Physics

We discuss the following problems, plaguing the present search for the “final theory”: (1) How to find a mathematical structure rich enough to be suitably approximated by the mathematical structures of general relativity and quantum mechanics? (2) How to reconcile nonlocal phenomena of quantum mechanics with time honored causality and reality postulates? (3) Does the collapse of the wave function contain some hints concerning the future quantum gravity theory? (4) It seems that the final theory cannot avoid the problem of dynamics, and consequently the problem of time. What kind of time, if this theory is supposed to be background free? (5) Will the dynamics of the “final theory” be probabilistic? Quantum probability exhibits some essential differences as compared with classical probability; are they but variations of some more general probabilistic measure theory? (6) Do we need a radically new interpretation of quantum mechanics, or rather an entirely new theory of which the present quantum mechanics is an approximation? (7) If the final theory is to be background free, it should provide a mechanism of space-time generation. Should we try to explain not only the generation of space-time, but also the generation of its material content? (8) As far as the existence of the initial singularity is concerned, one usually expects either “yes” or “not” answers from the final theory. However, if the mathematical structure of the future theory is supposed to be truly more general that the mathematical structures of the present general relativity and quantum mechanics, is a “third answer“ possible? Could this third answer be related to the probabilistic character of the final theory? We discuss these questions in the framework of a working model unifying gravity and quanta. The analysis reveals unexpected aspects of these rather wildly discussed issues.     

A Fast and Efficient Track to Allosteric Modulators of Muscarinic Receptors: Microwave-Assisted Syntheses

By using microwave irradiation bisammonium-and bispyridinium-type allosteric modulators of muscarinic receptors can be obtained fast and efficiently.