Transport properties in3He-4He mixtures near the superfluid transition

We report measurements of the temperature, density, and concentration gradients in³He-⁴He mixtures, induced by a vertical heat flux. The flat horizontal cell included two superposed capacitors and the density was determined by means of the dielectric constant method. The experiments were carried out on mixtures with mole fractionsX ₃=0.37, 0.15, and 0.05 at saturated vapor pressure, with special emphasis on the region near the superfluid transition. Our measurements under steady-state conditions give the conductivity , the thermal diffusion ratiok _T , and the coefficient of thermal expansion. We describe the singular behavior of these quantities in the neighborhood ofT (X). In the superfluid phase, we test with fair success a relation by Khalatnikov between gradX/ gradT and several static properties. From the relaxation times needed to attain steady-state conditions, and in combination with measured static and transport properties, we obtain in the normal phase the mass diffusionD, which diverges strongly asT is approached. In the superfluid phase, we test successfully a scaled relation that results from the solution of Khalatnikov's hydrodynamic equations. From our data the dispersion relations for scattered light are calculated: _o/q ² in both the normal and the superfluid phases and ₂/q ² in the normal phase.Research supported by NSF grant DMR 8024056.     

S-phase fractions of breast carcinomas. Relationships to morphology, estrogen and progesterone receptors, and early recurrence

Analysis of the S-phase fractions (SPF) measured by in vitro thymidine labeling, morphological appearances, and estrogen receptor (ER) assays of primary invasive breast carcinomas demonstrated several interrelationships. Lobular, mucinous, tubular, and adenocystic carcinomas consistently had low SPF and were usually positive for ER. The same was true for the carcinomas of no special histologic type [the not otherwise specified (NOS) group of E. R. Fisher including "infiltrating ductal" and undifferentiated carcinomas] with minimal anaplasia. Medullary, atypical medullary, and morphologically unclassifiable carcinomas with marked nuclear anaplasia nearly always had high SPF and were usually negative for ER. High SPF was associated with advanced stages of carcinoma initially or with early recurrence following mastectomy.     

The influence of light- and heavy-ion irradiation on the structure,resistivity, and superconducting transition temperature of V3Si. A comparative study

Channeling and x-ray diffraction measurements on Kr- and He-irradiated V₃Si single crystals and films reveal different damage levels for fluences in cases where the superconducting transition temperature T _chas been reduced by the same amount. This indicates that only special defect structures are responsible for the T _c-reduction mechanism. In the fluence region where T _cis decreasing, T _ccorrelates with residual resistivity _o, independent of the kind of irradiation. However, at particle fluences where T _csaturation occurs, different saturation values of _o are observed. The exponential decrease and the saturation of T _cwith fluence are explained by a similar behavior of g9_o versus fluence in the damage production and saturation processes. The increase of the lattice parameter is not uniquely dependent on the decrease of T _c, but also on the amount of damage present.     

Superconductivity,structural disorder,and phase transitions in ion-irradiated Nb3Al films

Thin films of single-phase A15 Nb₃Al were irradiated with protons and nitrogen ions. X-ray intensity analysis revealed a decrease of the Bragg-Williams long-range order parameterS and an increase of the average displacement amplitude of the atomsU in the fluence region where a decrease of the superconducting transition temperatureT _c was observed. The functional dependence ofT _c onS andU was found to depend on the ion species used for irradiation. After irradiation with 10¹⁶ N²⁺ / cm² the A15 phase transformed into an A2 phase. Furnace annealing caused a retransformation into the A15 phase with improved superconducting properties.     

NMR studies of single crystals of H2. V. NMR anisotropy and order parameter distribution ofX (ortho)≤0.55

We report a study of the NMR line shapes in hcp single crystals of H₂ with ortho concentrationsX0.55 in the regime where there is no longer a transition to a long-range orientationally ordered phase. From the anisotropy of the o-H₂ impurity NMR spectrum at low ortho concentration, reached by ortho-para conversion, the crystal orientation is determined. The second momentM ₂ can be represented by a function of the formM ₂=(X, T)f(cos _Hc ), where _Hc is the angle between the applied magnetic field and the crystalc axis. For a single crystal, the anisotropy functionf(cos _Hc ) is found to be independent of temperature and of ortho concentration within experimental error, and is in very good agreement with predictions based on the first term of the high-temperature expansion ofM ₂ and on other, more general symmetry arguments. An order parameter is defined and the distribution functionP() is calculated from the NMR line shapes under the simplifying assumption that the anisotropy of the order parameter, which gives rise to the observed anisotropy ofM ₂, can be neglected. We giveP() as a function ofX at low temperature, where the line shape is only weakly dependent onT, and as a function ofT at constantX. It is found that the line shapes andP() in both situations evolve continuously and give no hint of a phase transition. These results are discussed in relation to those of magnetic spin-glasses, and it is concluded that the orientational regime in solid H₂, called a quadrupolar glass by previous investigators, cannot be distinguished by symmetry from the orientationally disordered phase that occurs at high temperature.Work supported by NSF grants DMR-81-02993 at Duke University and DMR-79-10153 at the University of Pennsylvania.     

Occlusive phlebitis in multifocal fibrosclerosis

Multifocal fibrosclerosis, as the name implies, concerns disseminated fibrous processes that manifest as Riedel's thyroiditis, idiopathic retroperitoneal fibrosis, mediastinal fibrosis, sclerosing cholangitis, and pseudotumor of the orbit. Certain cases of fibrosis of the parotid gland, the lacrimal glands, and the lung may belong in the same category. The cases of two patients with Riedel's thyroiditis, one of whom also has retroperitoneal fibrosis, are described. Unusual changes in the small and middle-sized veins in the fibrous tissue in the thyroid and in the retroperitoneum, best designated "occlusive phlebitis," seem to be characteristic of the multifocal fibrosclerosis. They may contribute to the disease process.     

The effect of hydrogen in the mechanism of aluminum-induced crystallization of sputtered amorphous silicon using scanning Auger microanalysis

The metal-induced crystallization (MIC) of hydrogenated sputtered amorphous silicon (a-Si:H) using aluminum has been investigated using X-ray diffraction (XRD) and scanning Auger microanalysis (SAM). Hydrogenated, as well as non-hydrogenated, amorphous silicon (a-Si) films were sputtered on glass substrates, then capped with a thin layer of Al. Following the depositions, the samples were annealed in the temperature range 200 °C to 400 °C for varying periods of time. Crystallization of the samples was confirmed by XRD. Non-hydrogenated films started to crystallize at 350 °C. On the other hand, crystallization of the samples with the highest hydrogen (H₂) content initiated at 225 °C. Thus, the crystallization temperature is affected by the H₂ content of the a-Si. Material structure following annealing was confirmed by SAM. In this paper, a comprehensive model for MIC of a-Si is developed based on these experimental results.     

Knowledge integrators or weak links? An exploratory comparison of patenting researchers with their non-inventing peers in nano-science and technology

Summary Policy-makers in many countries emphasize the importance of non-publication output of university research. Increasingly, policies are pursued that attempt to encourage entrepreneurial activity in universities and public research institutes. Apart from generating spin-out companies, technology licensing, and collaborative research, attention is focused on patenting activities of researchers. Some analysts suggest that there is a trade-off between scholarly publication and patenting activity. This paper explores this relationship drawing on a data set of nanoscience publications and nanotechnology patents in three European countries. In particular, this study examines whether researchers who both publish and patent are more productive and more highly cited than their peers who concentrate on scholarly publication in communicating their research results. Furthermore, this study investigates the collaborative activity of inventor-authors and their position in their respective networks of scientific communication. The findings suggest that overall there seems to be no adverse relationship between publication and patenting activity, at least not in this area of science and technology. Patenting scientists appear to outperform their solely publishing, non-inventing peers in terms of publication counts and citation frequency. However, while they are considerably over-represented in the top performance class, the data indicates that inventor-authors may not occupy top positions within that group. An analysis of co-authorship links indicates that patenting authors can also play a prominent role within networks of scientific communication. The network maps also point to groups where inventor-authors occur frequently and others where this is not the case, which possibly reflects cognitive differences between sub-fields. Finally, the data indicates that inventor-authors account only for a marginal share of publishing scholars while they play a substantial role amongst inventors.     

Processing aspects in the low-frequency noise of nMOSFETs on strained-silicon substrates

The impact of different processing factors on the low-frequency (LF) noise of nMOSFETs fabricated in strained-silicon (SSi) substrates will be described. It is shown that the use of an SSi substrate can yield improved LF noise performance compared with standard Czochralski silicon material. This is demonstrated for both full-wafer and selective epitaxial SSi material. The lower 1/f noise points to an improved gate oxide quality, i.e., with a lower interface and bulk defect density, and is correlated with the low-field mobility or transconductance of the transistors. At the same time, it will be demonstrated that there exist defect-related LF noise mechanisms, which generally give rise to excess generation-recombination (GR) noise. Associated with this GR noise, a degradation of either the OFF-state leakage current or the mobility (transconductance) of the devices is observed. It is clear that noise is a sensitive parameter to local defectiveness and may be a useful tool for both materials' characterization and the analysis of processing-related device degradation mechanisms.