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Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces cell apoptosis by transducing apoptosis signals. Recently, accumulating evidence demonstrated that TRAIL regulates autoimmune inflammation and immune cell homeostasis in several autoimmune animal models, suggesting a novel immunoregulatory role of TRAIL in autoimmune diseases. However, the impact of TRAIL in inflammatory bowel disease is yet undefined. This study is to address the therapeutic effects and immunoregulatory role of TRAIL in autoimmune gut inflammation. We demonstrated herein that TRAIL significantly suppressed gut inflammation and reduced the severity of colitis in a dextran sodium sulfate (DSS)-induced colitis model. Suppression of gut inflammation was not due to induction of apoptosis in colonic T cells, dendritic cells, or epithelium cells by TRAIL. In contrast, TRAIL directly inhibited activation of colitogenic T cells and development of gut inflammation in an adoptive transfer-induced colitis model. The anti-inflammatory effects of TRAIL on colitis were abolished when T cells from TRAIL receptor (TRAIL-R) knockout mice were adoptively transferred, suggesting that TRAIL regulates autoreactive colitogenic T-cell activation in the development of gut inflammation. Our results demonstrate that TRAIL effectively inhibited colonic T-cell activation and suppressed autoimmune colitis, suggesting a potential therapeutic application of TRAIL in human inflammatory bowel disease.

After more than 50,000 dams were built in the Yangtze basin, especially the Three Gorges Dam (TGD) in 2003, the sediment discharge to the East China Sea decreased from 470 Mt/yr before dams to the current level of ~140 Mt/yr. The delta sediment's response to this decline has interested many researchers. Based on a dataset of repeated samplings at 44 stations in this study, we compared the surficial sediment grain sizes in the southern Yangtze subaqueous delta front for two periods: pre-TGD (1982) and post-TGD (2012). External factors of the Yangtze River, including water discharge, sediment discharge and suspended sediment grain size, were analysed, as well as wind speed, tidal range and wave height of the coastal ocean. We found that the average median size of the sediments in the delta front coarsened from 8.0 µm in 1982 to 15.4 µm in 2012. This coarsening was accompanied by a decrease of clay components, better sorting and more positive skewness. Moreover, the delta morphology in the study area changed from an overall accretion of 1.0 cm/yr to an erosion of − 0.6 cm/yr. At the same time, the riverine sediment discharge decreased by 70%, and the riverine suspended sediment grain size increased from 8.4 µm to 10.5 µm. The annual wind speed and wave height slightly increased by 2% and 3%, respectively, and the tidal range showed no change trend. Considering the increased wind speed and wave height, there was no evidence that the capability of the China Coastal Current to transport sediment southward has declined in recent years. The sediment coarsening in the Yangtze delta front was thus mainly attributed to the delta's transition from accumulation to erosion which was originally generated by river damming. These findings have important implications for sediment change in many large deltaic systems due to worldwide human impacts.

Ionic liquids (ILs) have been proposed as potential solvents for absorbing dichloromethane (DCM), while screening a promising IL with high absorption performances from numerous ILs remains challenging. In this work, a framework of multi-scale investigation on DCM absorption using ILs was established. A screening method based on COSMO-RS model that optimized by 79 reported experimental data points was proposed, and the effect of cationic and anionic structures on DCM absorption and the mechanisms were systematically studied combining quantum chemical calculation. Based on the above results, 1-ethyl-1-methylpiperidinium acetate ([C2MPip][C1COO]) was determined as the optimal IL for DCM absorption with Henry’s Constant of 3.29 kPa. The screened IL was further evaluated through process simulation comparing to the conventional IL and traditional organic solvent. The annual variable operation cost of [C2MPip][C1COO]-based process for DCM absorption was the lowest among the studied cases, showing broad prospects in applications.

This article aims to develop a Cartesian-grid-based numerical model to study the interaction between free-surface flow and stationary or oscillating immersed obstacle in a viscous fluid. To incorporate the effect of the free surface motion, an arbitrary Lagrangian-Eulerian (ALE) scheme is employed to accurately capture the configuration of free surface. To deal with the complex submerged obstacle in the fluid, a hybrid Cartesian/immersed boundary (HCIB) method is adopted, which allows easy implementation of the solid boundary conditions for a fixed structured grid. The two numerical techniques are combined to study the wave-structure interaction problems. The major merit of the proposed model is that the fluid grid is fixed throughout the computations during the transients, while the immersed body can move arbitrarily through the Cartesian grid. The meshes deform smoothly over the solid and free-surface boundaries, especially for representing sharp interface. There is no re-meshing process needed since this scheme only depends on the simple mesh generation to promote the efficiency of calculation. Some numerical examples are displayed respectively to validate the robustness and accuracy of the HCIB method, the ALE based finite-element scheme and their combinations. In addition, the other two numerical applications are carried out to simulate the wave-structure interaction with stationary and moving immersed body. In case studies some physical characteristics are also discussed for a range of amplitude of free-surface wave, Reynolds numbers and the proximity of structure under the liquid surface. The feasibility of the developed novel numerical model is shown through five numerical experiments.

We researched the structural effect of titania photocatalysts on the yield of hydrogen gas from water splitting. We synthesized mesoporous titania thin films (MTTFs) with two different structures (that is, pillar structure and tube structure, denoted as P-MTTFs and T-MTTFs, respectively) through an evaporation-induced self-assembling (EISA) process with the presence of a surfactant as a structure-directing agent. The synthesized MTTFs were carefully characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–Vis spectra. After analysis of photocurrent and hydrogen generation, we concluded that with different structures, MTTFs generate photocurrents and hydrogen with different efficiencies. The results indicated that the T-MTTF had a higher net current (i.e., 1.05 E−3 eV) than the P-MTTF (i.e., 1.04 E−3 eV). However, the yield of hydrogen from T-MTTFs (i.e., 17.5 μmol) was lower than that of P-MTTFs (i.e., 37.5 μmol). Tube structure induced a concentration gradient of NaOH, which restrained the generation of oxygen and hydrogen.

Fast multiple rotation rolling (FMRR), a novel and efficient surface nanocrystallization technique, was used to fabricate a nanostructured layer in the surface of low carbon steel. The microstructure of the surface layer was characterized by transmission electron microscopy, optical microscope and scanning electron microscopy, and mechanical properties were investigated by microhardness measurements, tensile measurements and friction and wear tests. In addition, the fracture and wear scars morphologies were observed by scanning electron microscopy. Experimental results indicated that a deformation layer with thickness about 200 μm is clearly observed in the FMRR sample surface. A nanostructured layer of 30 μm thick is obtained, with grain size ranging from 8 to 18 nm and average grain size about 14 nm in the top surface layer. The microhardness of the FMRR sample change gradiently along the depth from about 316 HV in the top surface layer to about 160 HV in the matrix, which is nearly twice harder than that of the original sample. The ultimate tensile strength has also been markedly improved. And the friction and wear experiments show that tribological properties of the low carbon steel have been enhanced by FMRR treatment.

The continuous production of biodiesel was studied by using a steady-state packed-bed reactor. The shell–core Ca(C3H7O3)2/CaCO3 solid-base catalyst was prepared with a mechanical strong core of CaCO3 for continuous transesterification of soybean oil in a packed-bed reactor. Alcohol–oil ratio, retention time and reaction temperature were evaluated to obtain optimum reaction conditions. The yield of fatty acid methyl esters (FAME, i.e. biodiesel) achieved 95% at the reaction temperature 60 °C, alcohol–oil molar ratio of 30:1 and retention time of 168 min. The reusability of catalyst was checked up to 5 cycles and found negligible decrease in the catalyst activity. Water in the oil can significantly decrease the yield due to the deactivation of Ca(C3H7O3)2 and hydrolysis of FAME. The transesterification of soybean oil, canola oil and sunflower oil also was compared with model compound, triolein, using powder Ca(C3H7O3)2 in the batch reactor. Although these oils contained different triglyceride mixtures, their FAME yields were comparable. A Langmuir–Hinshelwood rate equation was established for the transesterification of soybean oil with methanol. Regression of experimental data indicated that the transesterification was an endothermic reaction with the enthalpy change of 23,504 J/mol and the activation energy was 42,096 J/mol.

In vivo studies of mice were performed to investigate whether auto-reactive antibodies specific for self CD20 antigen on B cells could be induced by immunizing with a CD20 peptide linked to a foreign, human IgG.Fc fragment through a T cell immunologically inert linker peptide and how such an auto-reactivity, if generated, would affect the levels of B cells. The dimeric Fc fusion protein containing the extracellular 44-amino acid portion of CD20, and the CH2-CH3 domains of human gamma 1 immunoglobulin were prepared. After several subcutaneous immunizations with this CD20-Fc protein, mice produced anti-CD20 antibodies that can bind to native CD20 on normal B cells and B-lymphoma cells. In mice immunized with the CD20-Fc protein, the fraction of B cells in total peripheral blood lymphocytes decreased to about 40%, significantly lower than that of mice immunized with human IgG. In addition, antibody response towards an irrelevant bystander antigen, chicken ovalbumin, was weakened compared with that of mice immunized with human IgG. These results show that auto-reactive antibodies specific for CD20 can be induced by immunizing with an autologous CD20 peptide fused with a foreign IgG.Fc and that the auto-antibodies can partially reduce the levels of B cells and their response to other antigens.

The dc and rf performance of AlGaAs/GaAs high electron mobility transistors were measured after exposure to low pressure (5 mTorr) inductively coupled plasmas of H 2 or D 2 for various source (100–400 W) and chuck powers (10–100 W) and durations (1–4 min). The plasma exposure decreases drain–source current, increases gate leakage and increases the gate ideality factor, even at very low plasma powers and for short process durations. A number of physical and chemical effects are found to be responsible for the observed behavior, including preferential loss of As from the surface, creation of deep trap states by energetic ion bombardment and passivation of Si donors by formation of Si–H or Si–D neutral complexes.

Separation of polyvinylpyrrolidone, a water-soluble polymer of neutral charge, by high osmotic pressure chromatography (HOPC) is presented. HOPC, suitable for preparative separation of polymer by molecular weight, has been applied to various organic-soluble polymers. We demonstrate here that HOPC can also separate water-soluble polymers and is capable of separating fractions of narrower polydispersity compared to preparative gel permeation chromatography (GPC). Typically fractions with a polydispersity index (PDI) of 1.4–2 were generated from broad-distribution polymers (PDI∼5) in significant quantities from a single separation. By multi-stage separation, standard-grade fractions were obtained. Single- and multi-pass fractions were characterized by both GPC with narrow-standard calibration and GPC in tandem with a multi-angle laser light scattering detector.

This investigation presents several backup path building schemes for multicast connections in self-healing ATM networks. These restoration schemes are formulated as combinatorial optimization problems in which the objective functions minimize bandwidth usage and the constraints required to satisfy the survivability and physical limitations. Lagrangian based and greedy based heuristic algorithms are also developed to obtain the sub-optimal feasible solutions efficiently. In addition, the Lagrangian lower bounds are used to assess the quality of our heuristic solutions. Moreover, closely examining the gap between the heuristic upper bounds and the Lagrangian lower bounds reveal that the proposed algorithm can efficiently provide a nearly optimal solution for multicast connections in self-healing ATM networks.

Gas separations using commercial ceramic membranes with 40 A pore diameter were performed for three binary mixtures: H2/CO, H2/N2 and He/O2. The experimental conditions covered a wide range of temperatures (25 to 815°C) and pressures (3 to 38 atm). A mathematical model based upon Knudsen diffusion and intermolecular momentum transfer was developed to predict gas separation efficiency. The experimental results agreed well with the model prediction. The permeability of CO was substantially lower than the value expected from Knudsen diffusion. Nevertheless, the model developed was able to account for this phenomenon and predicted equally well for a binary mixture containing CO. The effect of key operating parameters on separation behavior was studied with the model developed.

Circular dichroism (CD) and Fourier transform infrared spectroscopic studies have shown that the secondary structure of transforming growth factor alpha (TGF-alpha) is very similar to that of epidermal growth factor (EGF). The infrared spectra revealed a minor difference between the two proteins, in particular in the beta-sheet structure. A large difference was observed with CD between the two proteins in the apparent conformation each adopts when the disulfide bonds are reduced. Reduced TGF-alpha showed a distinct alpha-helical conformation only at a high trifluoroethanol concentration, whereas reduced EGF assumed an alpha-helical conformation in the absence of trifluoroethanol. This indicates that these two proteins adopt different secondary structures in the absence of disulfide bonds, although they assume similar folding structures in their presence. These data suggest that the disulfide bonds to a large degree dictate the conformation of these two proteins. Additionally, differences in the dynamic behavior between EGF and TGF-alpha were also observed. Infrared experiments showed that the hydrogen-deuterium exchange rate is much higher for TGF-alpha than for EGF, indicating that TGF-alpha is a more flexible molecule. The rate of reduction of the disulfide bonds by dithiothreitol was also faster for TGF-alpha. Therefore, it can be concluded that although EGF and TGF-alpha have a similar overall conformation, TGF-alpha is a more flexible molecule than EGF.

A nuclear orientation facility using a 3 He/ 4 He dilution refrigerator and ferromagnetic host foils for the polarization of radioactive nuclei is described. A unique feature of this facility is the capability of studying the directional distribution of β particles ( E β > 100 keV) emitted by polarized nuclei over a wide range of angles without significant deflections of the β particle trajectories. Closed magnetic loops and high permeability source host foils are critical elements of the design that reduce stray magnetic fields in the region between the β source and the detector. This orientation facility has been used to completely map out the angular distribution of β particles emitted by polarized 60 Co nuclei. The observed angular distribution is in excellent agreement with the expected [1 + AP ( v / c cos θ ) dependence from the V-A theory of weak interactions. The experimental value of the β-asymmetry parameter ( A exp = −1.01 0.02) is consistent with maximal parity violation ( A theory = −1).

The energies and lineshapes of five circular transitions (n = 15 → n = 14 through n = 11 → = 10) of the Σ−Pb atom were measured wit of the transitions 15 → 14 through 12 → 11 were determined; these energies were compared with energies calculated from quantum electrodynamics, and the mass of Σ− was adjusted to achieve a best fit. The result was mΣ− = 1197.24 ±0.15 MeV. The lineshape of the 12→11 transition, which is broadened by the fine structure, has been analyzed to extract the magnetic moment of Σ−. The result was μΣ− = −1.40−0.28+0.41or 0.651−0.40+0.28 nuclear magnetons. Comparisons with SU (3) predictions are made.

The energies of the six circular transitions ( n = 13 → n = 12 through n = 8 → n = 7) of the K − Pb exotic atom have been measured to high precision (typically ∼ 50 ppm) using Ge (Li) spectrometers. The data acquisition system was computer controlled and stabilized, the energy calibration spectrum was taken simultaneously with the data spectrum. The experimental energies of the six transitions were corrected for ADC nonlinearities and data-calibration spectrum shifts, as well as the presence of unresolved noncircular transition contaminants. The energies of five of the transitions (13 → 12 through 9 → 8) were computed from quantum electrodynamics, including all significant orders of vacuum polarization, electron screening and nuclear polarization. The mass of the K − was adjusted to achieve a best fit with the experimental energies: the result was m K − = 493.657 ± 0.020 MeV.

The effective quadrupole moments Q eff of the nuclei of 165 Ho, 175 Lu, 176 Lu, 179 Hf and 181 Ta were accurately measured by detecting the pionic atom 5g-4f X-rays of the elements. The spectroscopic quadropole moments, Q spec , were obtained by correcting Q eff for nuclear finite size effect, distortion of the pion wave function by the pion-nucleus strong interaction, and contribution to the energy level splittings by the strong interaction. The intrinsic quadrupole moments, Q 0 , were obtained by projecting Q spec into the frame of reference fixed on the nucleus. The shift, e 0 , and broadening, Γ 0 , of the 4f energy level due to the strong interaction between the pion and the nucleons for all the elements were also measured. Theoretical values of e 0 and Γ 0 were calculated and compared to the experimental values. The measured values of Q 0 were compared with existing results in muonic and pionic atoms. The measured values of e 0 and Γ 0 were also compared with existing values.

Reactions produced by stopped negative pions on targets of 165 Ho, 175 Lu, 176 Lu, 179 Hf, and 181 Ta are investigated by measuring photons coincident with the stopped pions. These photons were detected with an 80 cm 3 Ge(Li) detector and identified as pionic X-rays or rotational γ-rays from the residual nuclei. Pion capture is found to result in the excitation of high-spin states. Yields for the residual nuclei are inferred from the observed γ-transitions and compared to calculations based on the exciton model for pre-equilibrium emission followed by particle evaporation. Preliminary results of a pion stop, γn coincidence experiment are presented and compared to the calculations.

The 60Co nuclei in a thin permendur foil were polarized by a pair of orthogonal magnetic flux loops at ultralow temperatures. The observed angular distribution and the asymmetry factor (Aexp = −1.01 ± 0.02) are in excellent agreement with theoretical predictions of (1 + α cos θ) dependence and Atheory = −1.0.

The systematics of ion-beam-induced intermixing of WSi 0.45 on GaAs has been studied after through-implantation of silicon or oxygen in the dose range 10 13 −5×10 16 cm −2 . Secondary ion mass spectrometry profiling shows significant knock-on of silicon and tungsten into the GaAs at the high dose range in accordance with Monte Carlo simulations, but there is virtually no electrical activation (less than or equal to 0.1%) of this silicon after normal implant annealing (900°C, 10s). This appears to be a result of the high level of disorder near the metal-semiconductor interface, which is not repaired by annealing. This damage consists primarily of dislocation loops extending a few hundred angstroms below the end of range of the implanted ions. Extrapolation of the ion doses used in this work to the usual doses used in GaAs device fabrication would imply that ion-induced intermixing of WSi x will not be significant in through-implantation processes.

The energies of the lower atomic transitions of the p and the K − atoms of 238 U have been measured. The measured values are significantly higher than the energies calculated from the electromagnetic interactions with the ground state of the 238 U nucleus. It is shown that the dynamic mixing of the first excited quadrupole state can explain such shifts.

The surface of ErSi 2 , formed by the reaction of thin erbium layers with a single-crystal silicon substrate, is typically dominated by deeply penetrating regularly shaped pits. These pits are shown to have detrimental effects on the electronic performance of Schottky barrier diodes. Surface pits may be reduced in density or eliminated entirely (i) by the use of silicon substrate surfaces prepared under ultrahigh vacuum conditions prior to metal deposition, (ii) by means of ion irradiation techniques or (iii) by reacting erbium with an amorphous silicon (a-Si) layer. In this investigation, planar ErSi 2 layers (pit free) are made using the third approach with a sample structure of a-Si/Er/c-Si where c-Si denotes crystalline silicon. The fast reaction between a-Si and erbium leads to a planar sample structure of ErSi 2 /c-Si with little or no reaction between erbium and the c-Si substrate. The electronic performance of pit-free ErSi 2 diodes made in this manner is shown to be much superior to that of diodes made by reacting erbium with silicon substrates.

A hybrid simulation model is used to investigate the effects of heavy cometary ions on the formation and structure of a cometary bow shock. The calculations are carried out over various Mach numbers and heavy ion velocity distribution functions. The model is based on previous formulations for phenomena in the solar wind and at the earth's bow shock. The generation of the shock is described in terms of particles injected from one side of the simulation field and reflected from the other end of the field, i.e., a solid wall boundary model. This technique permits the steep buildup of the ion density near the cometary nucleus, followed by coupling of the incident and reflected ion streams to produce a shock. It is shown that at low Mach numbers (up to Mach 2) the shock is transitory and periodically formed by protons, then destroyed by heavy ions (O+). Slightly higher Mach numbers lead to a true stationary shock. An examination of coupling effects between the solar wind and the heavy ions at low Mach numbers by using the Rankine-Hugoniot relations reveals that the ions and the solar wind protons cannot be treated as a single fluid calculating the shock characteristics.

Excitation of electron waves and whistlers by reflected auroral electrons which possess a loss-cone distribution is investigated. Based on a given magnetic field and density model, the instability problem is studied over a broad region along the auroral field lines. This region covers altitudes ranging from one quarter of an earth radius to five earth radii. It is found that the growth rate is significant only in the region of low altitude, say below the source region of the auroral kilometric radiation. In the high altitude region the instability is insignificant either because of low refractive indices or because of small loss cone angles.

The hyperfine spectra of muonic L and K X-rays of 209Bi have been reanalyzed by taking into account the resonance processes and the observed isomer shifts in addition to the M1 and the E2 interaction. The M1 and E2 hyperfine structure constants of the 1s, 2p and 3d muonic states and the nuclear static moments of the excited states 15 2 + and 9 2 + are determined from the best fits to the experimental spectra. The hfs constants and the M1 moments are in good agreement with theoretical predictions from the core excitation model. The quadrupole moment of the ground state remains to be 20% higher than that determined by the atomic beam method. A plausible interpretation is that this discrepancy might be due to the deformation of the lead core.

The L and K X-rays of muonic 205Tl have been measured with an enriched (99.8 %) 205Tl target. Two sets of resonance processes were included in the analysis, which led to satisfactory fits to the experimental spectra, and explain the anomalous intensity ratios between the fine structure components of the muonic L and K X-rays. At the same time, the M1 hyperfine structure constants, which show the finite distribution of the nuclear M1 moment, were determined. Also determined were the static nuclear E2 and M1 moments of the excited states.

The energies of the K and L muonic X-rays of six isotones in the region of tin ( Z = 50) have been measured, and the change in nuclear size on adding protons has been calculated. The effect of nuclear shell closing at Z = 50 is substantial.

The following ratios of quadrupole moments in the first excited 2+ state of 182,4,6W have been measured simultaneously using the Mossbauer effect following Coulomb excitation: 1:(0.930±0.016) : (0.908±0.024). Single crystals of WS2 have been used as the absorbers. These results are compared with the rotational model and the calculations of Kumar and Baranger.

The decay scheme of 82 Br has been reinvestigated with a Ge(Li) detector. A total of 11 weak gamma rays were observed in addition to the eight well-known ones. Time coincidences have been established for the following cascades, 222-1650-777 keV, 1008–1044 keV and 606–1044 keV gamma rays. Possible spin assignment of 3 + or 4 + to the newly established energy level 2426 keV has been obtained through angular correlation measurements between 1650-777 keV gamma rays. The peaks at 1650 keV, 1778 keV and 1955 keV have been shown to be the gamma rays of 82 Br. The peak at 1868 keV is due to true coincidence summing effect. No peak at 2057 keV was observed.

Double-photon decay in the 0 + to 0 + transition in 90 Zr was measured with two large-volume Ge(Li) detectors, at angles of 90° and 180°. The branching ratio of double-photon decay with respect to the sum of internal-conversion electrons and internal pairs was (3.17 ± 0.77) × 10 −4 . The angular correlation of two photons is in agreement with that of (E1, E1) transition, although it does not exclude other possibilities.

A 53 cm dia., 8 cm deep helium-filled streamer chamber is described. At a field strength of 6.2 kV/cm, streamers extend over the entire space between the plates of the chamber and the particle track is shown by bright, narrow regions in the streamers. The mechanism of electrical breakdown in this mode of operation and other modes was investigated. The streamer theory of Raether correctly predicts breakdown-time and dead-space. Penning effect by impurities in the chamber gas appears to influence discharge development significantly at the low field strengths used in track-projecting chambers but not at the high field strengths used in streamer chambers.

It is suggested that the Jovian decametric emissions (DAM) originate in a cyclotron instability of weakly relativistic electrons trapped in the Jovian magnetic field. The resulting radiation has a group velocity in the magnetospheric plasma which may be of order 100 km/sec, and thus takes much more time to escape the magnetosphere than if the group velocity were at or near the speed of light. Therefore, the asymmetry of the Io phase with respect to sources east and west of the Earth-Jupiter line does not imply an asymmetric beaming of DAM; it is caused by the delay the waves experience in traversing the magnetosphere. The frequency drifts of milli- and decasecond bursts are also explained.

With a Ge(Li) detector, we have studied the γ-ray spectrum of 47 Sc (populated by β-decay of 47 Ca). The results obtained were (i) two weak γ-rays (0.5324±0.0007 and 0.7640±0.0007 MeV were observed in the singles spectrum; (ii) the intensities of the γ-transitions were determined to be (0.17±0.02) % of the total transition rate from the 1.2945 MeV level; (iii) from the delayed coincidence spectrum, the 0.7640 MeV line was found to be the only transition deexciting the metastable state; (iv) from the time-to-pulse-height spectrum, the half-life was more accurately measured to be 270±12 nsec. In addition, the technique of applying the Ge(Li) detector to coincidence work in spectroscopic studies is described.

It has been known for some time that the intensity ratio between the (2p3/2-Is1/2) and (2p1/2-Is1/2) muonic X-rays for 127I is anomalously smaller than the theoretical value 1.95. Several theorists(1),(2),(3) have suggested that this may be explained by nuclear resonance excitation. We have observed the muonic N, M, L and K X-rays from 127I, and have calculated a theoretical spectrum within the framework of a resonance process. The resonance is between the 2p fine structure splitting and the nuclear ground and the first excited states. A satisfactory fit to the experimental data has been obtained. From this fit we have determined the M1 and E2 hfs constants for the is and 2p states, and have obtained a quantitative interpretation of the observed intensity ratios.

A new experimental investigation of double beta decay in 48Ca using apparatus of unique sensitivity and discrimination is reported. We obtain a lower limit of 1.6 × 1021 years at a statistical confidence level of 80% for the lifetime of the lepton-nonconserving neutrinoless mode, and of 3 × 1019 years for the lepton-conserving two-neutrino mode.

Construction of a model neutral and ion exosphere for a planet weakly interacting with the solar wind. The model is constructed in general terms and is then specialized to possible neutral and ion exospheres for the planet Mercury. The neutral exosphere model allows for density and temperature variations and for rotation at the exobase. The ion exosphere is produced by ionization of the neutral exosphere in the solar wind, and its density distribution is obtained by solving the continuity equation in the drift approximation. Applying to Mercury a surface temperature distribution inferred from infrared data and a vanishing bound neutral flux at the base, He and He(+) density distributions are found. When the He atmosphere of Mercury is due entirely to the surface bombardment by solar wind He(2+), the resulting He(+) density is found to vary from 0.15 to 0.001 per cu cm over the range from 1.5 to 5 planetocentric radii on the dayside. These densities are found to be detectable by typical solar-wind plasma instruments.

Although recent mass-spectrometer experiments have shown convincingly that double beta decay does take place, observation of the decay electron spectrum is necessary to be certain whether two neutrinos are emitted (as expected assuming lepton conservation) or none (implying lepton nonconservation). An attempt to measure the electron spectrum from the double beta decay of 48 Ca was made in a deep salt mine, using a streamer chamber in a magnetic field. In 1150 hours of observation with a 10.6 g source, only one event was seen which might be neutrinoless double beta decay, implying a half-life of > 2 × 10 21 y at the 80% confidence level. This in turn implies that any violation of lepton conservation must be of the order of 10 −3 or less. A half-life limit of > 3.6 × 10 19 y for the two-neutrino mode of 48 Ca double beta decay was also obtained.

The nuclear finite-size effect in the M1 hyperfine structure of muonic atoms of 93Nb and 139La has been studied experimentally. Systematic differences of the finite-size effect between nuclei in which the spin and the orbital angular momentum of the odd proton are parallel or anti-parallel are discussed.

The quadrupole-moment ratios of the first excited 2 + states of 176 Hf and 180 Hf have been measured with the Mossbauer effect following Coulomb excitation. The target was a single crystal of metallic hafnium with its c -axis making an angle of 45° with the surface of the crystal. Three absorbers of cubic crystals of HfC were prepared with seperated 176, 178 and 180 Hf isotopes. The determined ratios are Q 22 (80): Q 22 (178): Q 22 (176) = 1 : (1.03 ± 0.02). These results are compared with the predictions from the rotational model.