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Cross-linked poly(methyl methacrylate) (PMMA) was synthesized to high conversion with 0.02−0.5 wt % ¹³C- or ²H-labeled ethylene glycol dimethacrylate (EGDMA). Samples were analyzed with a variety of NMR techniques to examine different cross-linker reaction products (or architectures), i.e., pendant EGDMA methacrylates, cyclized EGDMA, and cross-linked EGDMA. Solid-state ¹³C NMR spectroscopy was not applicable because poor peak resolution masked the cross-linker architecture peaks. Solid-state ²H NMR spectroscopy of deuterium-labeled EGDMA was also not useful because the deuterium line shape was convoluted by signals from natural abundance deuterium in the polymer. Solution ¹³C NMR analysis of solvent swollen polymers (gel-state ¹³C NMR spectroscopy) produced well-resolved spectra of copolymers containing less than 0.5 wt % ¹³C-labeled EGDMA. These spectra confirm that significant amounts of EGDMA were singly reacted, resulting in large numbers of pendant methacrylate units. Non-cross-linked and completely soluble model PMMA copolymers containing 0.1 wt % ¹³C-labeled pendant EGDMA methacrylates units (incorporated in a postpolymerization reaction) were used to identify the ¹³C NMR signals characteristic of EGDMA pendant units. Signals from the stereochemical triads (syndio- and heterotactic) were identified, but specific peaks for nine-membered cyclic EGDMA units were not observed. The detection limit of gel-state ¹³C NMR analysis on these MMA/EGDMA copolymers was as low as 0.02 wt % ¹³C-labeled EGDMA, which demonstrates the utility of this approach for characterizing lightly cross-linked polymers.

Abstract: Particle production in Au+Au collisions has been measured in the PHOBOS experiment at RHIC for a range of collision energies for a large span of pseudorapidities, |η| < 5.4. Three empirical observations have emerged from this data set which require theoretical examination. First, there is clear evidence of limiting fragmentation. Namely, particle production in central Au + Au collisions, when expressed as dN/dη′ ( η′ ≡ – ybeam), becomes energy independent at high energy for a broad region of η′ around η′ = 0. This energy-independent region grows with energy, allowing only a limited region (if any) of longitudinal boost-invariance. Second, there is a striking similarity between particle production in e+e−and Au + Au collisions (scaled by the number of participating nucleon pairs). Both the total number of produced particles and the longitudinal distribution of produced particles are approximately the same in e+e−and in scaled Au + Au. This observation This presentation is based in large part on the PHOBOS summary talk by M Baker at the16th Int. Conf. on Ultrarelativistic Nucleus- Nucleus Collisions, Quark Matter 2002, Nantes, France was not predicted and has not been explained. Finally, particle production has been found to scale approximately with the number of participating nucleon pairs for (N part ) > 65. This scaling occurs both for the total multiplicity and for highp T particles (3

T < 4.5 GeV/c).

Secreted protein acidic and rich in cysteine (SPARC) has a suppressive effect on U87 glioma cell proliferation when assessed in vitro and in vivo using parental U87T2 and U87T2-derived SPARC-transfected clones. Since SPARCinteracts with extracellular matrix (ECM) proteins, we examined the effect of SPARC secretion on proliferation, morphology, and cell density of glioma cells grown in vitro, in the absence and presence of ECM proteins under standard (10% fetal bovine serum [FBSI) and reduced (0.1% FBS) serum stress conditions. Under standard conditions, MTT (3-(4,5-cimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide) growth curves, morphology, and Western blot analyses demonstrated that SPARC had a suppressive and biphasic effect on growth that was not grossly modulated by the ECMs. The SPARC-induced changes in morphology observed at 24 h were not altered by the presence of ECMs. Under reduced-serum stress conditions, Western blot, morphological, and flow cytometric analyses indicated that the SPARC-induced suppressive growth effects were eliminated when the cells were grown on plastic. However, ECM-specific changes in growth were observed, some of which correlated with secreted SPARC levels. These results indicate that the differential effects of SPARC and ECMs on proliferation are dependent on culture conditions. Since the results obtained under standard conditions agree with our in vivo observations, we conclude that the ability of SPARC to suppress proliferation is regulated to a greater degree by the level of SPARC and that this suppressive effect is not influenced by the presence of any of the ECMs examined.

Abstract: The PHOBOS detector has been used to study Au + Au collisions at√sNN = 56,130, and 200 GeV Several global observables have been measured and the results are compared with theoretical models. These observables include the charged-particle multiplicity measured as a function of beam energy, pseudo-rapidity, and centrality of the collision. A unique feature of the PHOBOS detector is its almost complete angular coverage such that these quantities can be studied over a pseudo-rapidity interval of |η|≤5.4. This allows for an almost complete integration of the total charged particle yield, which is found to be about N chtot = 4200 ±470 at √sNN = 130 GeV and N chtot = 5300 ±530 at √sNN = 200 GeV. The ratio of anti-particles to particles emitted in the mid-rapidity region has also been measured using the PHOBOS magnetic spectrometer. Of particular interest is the ratio of anti-protons to protons in the mid-rapidity region, which was found to be (i.e.921-1) at √sNN = 130 GeV. This high value suggests that an almost baryon-free region has been produced in the collisions.

Using a 2,2,2-trifluoroethanol/deuteriochloroform solvent mixture (TFE/CDCl3), well-resolved solution ¹³C NMR spectra of nylon 66 samples were obtained that showed several low-intensity peaks not seen in other, more acidic solvents. These low-intensity peaks were correlated to the methylene carbons near cis amide conformers, acid and amine end groups, and within cyclic oligomers. On the basis of relative peak intensities, the quantitative contents of these components for a typical sample of nylon 66 were determined to be 1.1 mol % cis amide conformers, 1.0 mol % acid end groups, and 0.5 mol % amine end groups. A number-average molecular weight of 30 177 g/mol was calculated from end group concentrations, which is a typical value for commercial nylon 66 samples. The chemical shift values of methylene carbons contained in end groups and in cyclic oligomers were found to be pH sensitive and therefore dependent on the relative concentrations of acid and amine end groups present in each sample. Understanding this behavior, in conjunction with the peak assignments described here, allows identification and quantitation of structural units and contaminants important in controlling chemical and physical properties.

Abstract: An 80-MeV/c negative muon beam from the Alternating Gradient Synchrotron at Brookhaven National Laboratory was used to investigate the stopping of muons inside Pd, Ti, and Y targets saturated with deuterium. Neutron emission from the targets was measured with an array of3He detectors, and in some runs, the temperature of the target was monitored as a function of time, with and without a flux of muons on the target. The neutron rates were also measured for Pd cathodes in an active electrochemical cell similar in design to those used in so-called “cold fusion” experiments, and the electrolyte solution was analyzed for excess tritium. No evidence was found for muon-catalyzed fusion at rates consistent with those claimed in “cold fusion” experiments. Neutron production from catalyzed fusion due to the presence of deuterium in palladium deuteride, PdD0.7, exposed to muons was determined to be 0.00.03 (stat.) 0.25 (syst.) neutrons per stopped muon.

The first measurement with the E-802 spectrometer has been made in April, 1987 using 14.5 GeV/c per nucleon28Si beam accelerated at the Tandem-AGS accelerator complex. In Si+Au collisions with the angular coverage of 14°–28° (midrapidity), a remarkable difference between the production rates ofK+ andK- was found and the observedK+/p+ ratio is 24±5%, while theK-/p- ratio is 4-2+4% in the momentum range ofplab < 2.0 GeV/c for central triggers.

The first data from a16O beam of total energy 232 GeV at the BNL Tandem-AGS are discussed. Preliminary results from a28Si beam of total energy 406 GeV are also shown. The full complement of E802, including a magnetic spectrometer, was used for the28Si measurement. A different experimental arrangement was used for16O. Comparison measurements with proton beams are presented for both configurations.

Abstract: The microstructure and mechanical properties of extruded specimens of a block copolymer-homopolymer polyethylene blend have been extensively studied. Through careful control of the blending and extrusion process, the dispersed polyethylene phase can develop,in situ, to yield stiff fibres having a tensile modulus of about 15 GPa. This fabrication strategy for composite materials is now being extended to the production of materials having ultra-high modulus polymeric fibres as well as those possessing novel combinations of physical properties.

a particles were measured in coincidence with projectile-like reaction products (oxygen and carbon) produced in deep-inelastic16O+58Ni collisions at about 6 MeV/N bombarding energy. The kinematic analysis of the HI anda energies measured as a function ofTa gives strong evidence for a sequential process: the target-like fragments are excited by the deep-inelastic collision and undergo subsequenta decay. In contrast, the angular correlations show a pronounced forward peak, indicative of direct or pre-equilibriuma emission. The emission time for the latter is estimated to be of the order of 2×10-21 s. To resolve this conflict of co-existing statistical and direct features of the pre-equilibrium emission, the concept of a hot spot is proposed. From the angular correlation and from thea multiplicities, a local temperature ofT-3.5 MeV is deduced which agrees well with the temperature derived from the shape of thea spectra. The spot size is estimated to be 1/5 of the sphere.

Background: Retrospective analyses have shown that long-term recurrence rates after Lichtenstein mesh and Shouldice herniorrhaphies are low. Therefore differences in short-term outcome may be important determinants of one's choice of repair. Although proponents of the mesh repair claim that their method is less morbid, to our knowledge no prospective comparative studies of short-term morbidity have been reported. Methods: One hundred five adult patients were randomized to undergo either a mesh or Shouldice inguinal hernia repair. Postoperative pain, narcotic use, and time to resumption of usual activities and employment were recorded. Patients were blinded to the type of repair received until all data were collected. Results: There was no difference between the herniorrhaphy methods with respect to postoperative pain, duration of narcotic use, and time to resumption of usual activity and employment. Recovery was rapid for both groups of patients. By 3 days after operation, 50% of patients rated their pain as very mild or less and no longer required narcotic analgesics. Patients in both groups returned to usual activity and work by a median of 9 days after operation. Conclusions: Both of these well-established methods can be used to repair inguinal hernias with local anesthetics in an outpatient setting with minimal morbidity. Despite the ''tension-free'' design of the mesh repair, short-term outcomes of mesh and Shouldice repairs of inguinal hernias do not differ. (Surgery 1998;123:121-6.)

TheE4 transition matrix element from the ground state to the 4+state has been measured in152Sm and154Sm, by comparing relative thick targetγ-ray intensities following Coulomb excitation with 12 MeV4He, 24–30 MeV16O, and 35–40 MeV32S projectiles. Values for 〈0+∥ℳ(E4)∥4+〉 of (+0.31−0.20+0.12) barn in152Sm and (+0.50−0.12+0.09) barn in154Sm are found.

Møller scattering is one of the most fundamental processes in QED, and a variety of modern experiments require its knowledge to high precision. A recent calculation considered the radiative process at low energy, where the electron mass cannot be neglected. To test the calculation, an experiment was carried out using the Van de Graaff accelerator at the MIT High Voltage Research Laboratory. Momentum spectra at three scattering angles are reported here and compared to simulation, based on our previous calculation. Good agreement between the measurements and our calculation is observed. [ABSTRACT FROM AUTHOR]