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Using a cross-sectional study, 246 patients with hemorrhage and transformation after cerebral ischemic stroke(CIS) thrombolysis who were admitted to Shangqiu First People's Hospital, Shangqiu Municipal Hospital, and Shangqiu Liangyuan Traditional Chinese Medicine Hospital from March 2018 to May 2020 were selected as the observation group, 246 patients with no hemorrhage transformation after CIS thrombolysis during the same period were selected as the control group with a ratio of 1∶1. Polymerase chain reaction and pyrosequencing methods were used to detect the single nucleotide polymorphisms of the two groups of本研究采用横断面研究，选取2018年3月至2020年5月商丘市第一人民医院、商丘市立医院、商丘市梁园区中医医院收治的246例缺血性脑卒中（cerebral ischemic stroke，CIS）溶栓后发生出血转化患者作为观察组，以1∶1配比选取同期CIS溶栓后未发生出血转化患者246例作为对照组。采用聚合酶链反应和焦磷酸测序法，检测两组

In this paper, concurrent/colocated measurements of seismometers, infrasonic systems, magnetometers, HF-CW (high frequency-continuous wave) Doppler sounding systems, and GPS receivers are employed to detect disturbances triggered by seismic waves of the 11 March 2011 M9.0 Tohoku earthquake. No time delay between colocated infrasonic (i.e., super long acoustic) waves and seismic waves indicates that the triggered acoustic and/or gravity waves in the atmosphere (or seismo-traveling atmospheric disturbances, STADs) near the Earth's surface can be immediately activated by vertical ground motions. The circle method is used to find the origin and compute the observed horizontal traveling speed of the triggered infrasonic waves. The speed of about 3.3 km/s computed from the arrival time versus the epicentral distance suggests that the infrasonic waves (i.e., STADs) are mainly induced by the Rayleigh waves. The agreements in the travel time at various heights between the observation and theoretical calculation suggest that the STADs triggered by the vertical motion of ground surface caused by the Tohoku earthquake traveled vertically from the ground to the ionosphere with speed of the sound in the atmosphere over Taiwan.

Biotreatment of spent sulfidic caustic with different dilution ratios was investigated in this study. The results show that the domesticated activated sludge has an effective biodegradability in the treatment of the spent caustic with a dilution ratio of 3. The sulfur compounds were completely biodegraded within one cycle period. The degradation of sulfur compounds was a process of alkalinity consuming. Sulfide was mainly bio-oxidized to sulfate under the conditions of low sulfide load and sufficient dissolved oxygen. The conversion of sulfide to sulfate decreased by 24% as the dilution ratio reduced from 10 to 3. Meanwhile, the activity of sulfur bacteria recovered quickly after impact.

The potential of biological degradation of refinery spent caustic is evaluated in this study, including effects of operating parameters such as pH of influent stream, salinity, and air flowrate on the biotreatment of the spent caustic process. The results show that the sequence batch reactor process by using domesticated activated sludge has an effective biodegradability on refinery spent caustic. The chemical oxygen demand (COD) removal efficiency reached above 80% with an initial COD value of 1000 mg/L, and the degradation rate of sulfide was over 95%. Meanwhile the organic components of the spent caustic were completely biodegraded within one cycle time.

The leucine-rich repeats and PDZ (LAP) family of genes are crucial for the maintenance of cell polarity as well as for epithelial homeostasis and tumor suppression in both vertebrates and invertebrates. Four members of this gene family are known: densin, erbin, scribble and lano. Here, we identified the four members of the LAP gene family in Xenopus tropicalis and studied their expression patterns during embryonic development. The Xenopus LAP proteins show a conserved domain structure that is similar to their homologs in other vertebrates. In Xenopus embryos, these genes were detected in animal cap cells at the early gastrula stage. At later stages of development, they were widely expressed in epithelial tissues that are highly polar in nature, including the neural epithelia, optic and otic vesicles, and in the pronephros. These data suggest that the roles of the Xenopus LAP genes in the control of cell polarity and morphogenesis are conserved during early development. Erbin and lano show similar expression patterns in the developing head, suggesting potential functional interactions between the two molecules in vivo.

The evolutionarily conserved Dbx homeodomain-containing proteins play important roles in the development of vertebrate central nervous system. In mouse, Dbx and Nkx6 have been suggested to be cross-repressive partners involved in the patterning of ventral neural tube. Here, we have isolated Xenopus Dbx2 and studied its developmental expression and function during neural development. Like XDbx1, from mid-neurula stage on, XDbx2 is expressed in stripes between the primary motoneurons and interneurons. At the tailbud stages, it is detected in the middle region of the neural tube. XDbx2 acts as a transcriptional repressor in vitro and over-expression of XDbx2 inhibits primary neurogenesis in Xenopus embryos. Over-expression of XDbx genes represses the expression of XNkx6.2 and vise versa. Knockdown of either XDbx1, XDbx2 or both by specific morpholinos induces lateral expansion of XNkx6.2 expression domains. These data reveal conserved roles for Dbx in primary neurogenesis and dorsoventral neural patterning in Xenopus.

The wind-induced mean, background and resonant responses of Beijing National Stadium are investigated in this paper. Based on the concepts of potential and kinetic energies, the mode participation factors for the background and the resonant components are presented and the dominant modes are identified. The coupling effect between different modes of the resonant response and the coupling effect between the background and resonant responses are analyzed. The coupling effects between the background and resonant components and between different modes are found all negligible. The mean response is approximately analogous to the peak responses induced by the fluctuating wind. The background responses are significant in the fluctuating responses and it is much larger than the resonant responses at the measurement locations.

This review discusses the recent experimental and computational investigation on the mechanical behavior of carbon nanotubes (CNTs), CNT assemblies, and their composites. The focus is on the hierarchical structure, deformation mechanisms, and mechanical properties of pristine CNT/CNT assemblies as well as interfacial properties and toughening mechanisms of their composites. We first introduce current research on mechanical performance of CNTs and CNT composites. Then, we focus on fabrication technologies, multiscale experimental investigations, and numerical simulations of CNT assemblies, including covalent assemblies and non covalent assemblies. Finally, we discuss the interfacial properties of CNT fiber composites. The bulk of this chapter is devoted to current research on the mechanical behavior of CNT and CNT fibers as well as the toughening mechanisms of their composites.

A high-Tc SQUID-based non-destructive evaluation (NDE) system has been set up in our laboratory. The SQUID was made on a 24° bicystal SrTiO3 substrate. A novel quadruple excitation coil was proposed for the first time and applied in the artificial holes in the aluminium multilayer structure in a noisy unshielded environment. The experimental data shows that it has good balance and is very effective at detecting small hole defects.

We present a modified normalized least-mean-square algorithm for SQUID-based magnetocardiography data processing with a new error function, in which the instantaneous signal component represented approximately by an average of near past error data has been eliminated. In this way, the rebounds of the weight vector W from its optimal value in parameter space due to the signal component can be well avoided.

A general description of spontaneous magnetization in multi-junction π-rings is given by considering the free energy of the system. The magnetization flux of π-rings in the ground states as a function of screen parameter β is discussed. Based on the description, a model with an infinitely large one-dimensional π-ring array in the absence of external magnetic field is analysed. The result shows that the ground state corresponds to the full antiparallel pattern of magnetization flux generated in the π-rings, which is in agreement with the experimental results obtained by Hilgenkamp et al (2003 Nature 422 50) in large-scale YBCO corner junction arrays.

The SQUID microscope is the most suitable instrument for imaging magnetic fields above sample surfaces if one is mainly interested in field sensitivity. In this paper, both the magnetic moment sensitivity and spatial resolution of the SQUID microscope are analysed with a simple point moment model. The result shows that the ratio of SQUID sensor size to sensor–sample distance effectively influences the sensitivity and spatial resolution. In comparison with some experimental results of magnetic images for room temperature samples from our high-Tc SQUID microscope in an unshielded environment, a brief discussion for further improvement is presented.

Quantum manipulation means controlling the states of single and multiple quantum-bit (qubit) by some methods. In this paper, we discuss a Cooper-pair charge qubit system composed of symmetrical dc SQUID’s or low-capacitance Josephson corner junctions made up of d- and s-wave superconductors. Single- and two-qubit operations can be realized in the system by controlling the gate voltages and external magnetic fields in an easy way.

Magnetic penetration depth \ensuremath{\lambda} in Nb/Al and Nb/Cu superconducting bilayers, its absolute values and temperature dependencies under the variations of material and sample parameters are systematically investigated. Measurements of \ensuremath{\lambda} are performed by using the two-coil mutual inductance technique and the results are compared with a recent microscopic theory [Phys. Rev. B 59, 14 630 (1999)] based upon Eilenberger-Usadel's quasiclassical equations of superconductivity. Our results show that the $\ensuremath{\lambda}(T)$ characteristics at low temperatures usually follow a power law, or a linear temperature dependence, if the sublayer thicknesses are less than several times of their coherence length and the interface resistance is small. A two-gap, steplike feature in the $\ensuremath{\lambda}(T)$ curve of the Nb/Al bilayer system will develop around the sublayer transition temperature of Al when the interface resistance increases or when the Al layer thickness becomes much larger than its coherence length. These results can be well described within the framework of the microscopic theory.

In cooperation with Alfa Laval Thermal AB Company in Sweden, a steam condensation test rig of a plate heat exchanger (PHE) was set up. The heat transfer and pressure drop characteristics of two kinds of typical operation condition in a PHE were obtained: complete condensation and partial condensation. This article introduces the test rig, various sensors, and the data acquisition system used in the measurements. The process of steam condensation in a PHE is analyzed in detail. The two-phase frictional pressure drop along this wavy channel was obtained from the measured steam condensation pressure drop. The Lockhart-Martinelli model was extended to predict the pressure drop of steam condensation in a PHE and was verified by the experimental results. Based on the data processing of 109 experimental points, a correlation of frictional pressure drop of steam condensation in a PHE is suggested. This correlation is recommended for calculation of the steam condensation pressure drop in a PHE.

Close-contact melting processes of phase change material (PCM) inside a horizontal elliptical tube are studied. The theoretical formulas of the melting rate, thickness of liquid layer, elapsed time of solid PCM and Nusselt number during the heat melting process are obtained by analyzing. The results include those of contact melting inside a horizontal cylinder. Finally, the influences of elliptical compression coefficient and temperature difference in melting are discussed, and useful conclusions are drawn. © 1998 by John Wiley & Sons, Ltd.

Most hydrogels exhibit coupled chemo-mechanical behaviors when in an aqueous environment with changing salt concentrations. This work presents a theoretical framework and a numerical procedure to describe the coupled mechanical deformation and solvent diffusion of such ion-sensitive hydrogels. A new variational formulation for the coupled governing equations is formulated by implementing the coupled formulations in a finite element procedure in Eulerian frame and further the time-dependent concurrent process of mechanical deformation and solvent diffusion is numerically investigated. The proposed numerical method is demonstrated by analyzing several chemo-mechanical coupling phenomena of initially-swollen hydrogels, such as transient free-swelling and indentation with a spherical punch. The results show that the present model is capable of simulating transient free-swelling and solvent migration in such smart materials subjected to externally-applied mechanical forces.

In order to accelerate a heavy train model with a large dimension to a velocity higher than 500 km/hour for the moving model test, the compressed air is utilized to drive the model indirectly. The gas from an airgun impels a piston in the accelerating tube for a uniformly acceleration. The piston connects a driving device through a rope and the device promotes or pulls the train model for a desired velocity. The deceleration of the train model and the driving device are all realized by the friction between the brake plates and the rubber blocks. The principium experiment results reveal that the initial pressure of the airgun is linearly proportional to the kinetic energy of the model where the moving assembly with a weight more than 10 kg has been accelerated to 420 km/hour in an accelerating distance of 20m.

The sea-floor deposit is assumed to be a saturated porous medium modelled by a two-phase system for which the coupled governing equations are derived from the theory of mixture. A constitutive model based on the generalized plasticity-bounding surface formulation is proposed to describe the soil behavior. An artificial boundary is suggested to deal with the unbounded domain problem. The coupled governing equations and the material model have been implemented into a nonlinear finite element program to analyze the travelling wave-induced liquefaction of seabed deposits. The results of two case studies are presented. The first case examines the response of sand deposit to the wave train at a site of underwater pipelines for nuclear power plants in Lake Ontario where the deposit was found to vary from loose to medium dense. The second case investigates the sea-floor behavior under a storm wave at the Ekofisk oil tank site in the North Sea where the deposit was reported to be dense. The results agree with the field observations. Key words: seabed instability, liquefaction, finite element, plasticity, sand, cyclic loading, travelling wave, unbounded domain.

We report theoretical and experimental studies of the dynamics of substrate step preparation for high-Tc Josephson junctions. A maximum step edge angle of 70.8° has been calculated for SrTiO3 (STO) substrates with a Nb mask. This calculated angle agrees well with our experimental result of 66°. Step-edge angles can be predicted for different purposes using this method. We also utilized a “two-step process” to improve the surface morphology of the stepped substrate, and step-edge Josephson junctions were fabricated with good uniformity.

Multiple lines of evidence have shown that the functional defect of pancreatic beta cells is the root cause of type 2 diabetes. FoxO1, a key transcription factor of fundamental cellular physiology and functions, has been implicated in this process. However, the underlying molecular mechanism is still largely unknown. Here, we show that the overexpression of FoxO1 promotes the proliferation of cultured pancreatic beta cells exposed to low nutrition, while no change in apoptosis was observed compared with the control group. Moreover, by using two specific inhibitors for PI3K and MAPK signaling, we found that FoxO1 might be the downstream transcription factor of these two pathways. Furthermore, a luciferase assay demonstrated that FoxO1 could regulate the expression of Ccnd1 at the transcription level. Collectively, our findings indicated that FoxO1 modulated by both MAPK and PI3K signaling pathways was prone to cause the proliferation, but not the apoptosis, of pancreatic beta cells exposed to low nutrition, at least partially, by regulating the expression of Ccnd1 at the transcription level.

Trpp5 is one member of the polycystic kidney disease (PKD) family, which belongs to transient receptor potential (TRP) superfamily. Our previous study has shown that Trpp5 is developmentally expressed in mouse testis and overexpression of Trpp5 increases intracellular free calcium concentration in MDCK cells. However, the roles of this protein in cellular processes are largely unknown. Here, we demonstrated that Trpp5 resided in both cytoplasm and cell membrane of HEK293 cells. We found that overexpression of Trpp5 slightly increased the calcium current amplitude of HEK293 cells and shifted the reversal potential to a more negative value. Meanwhile, overexpression of Trpp5 suppressed proliferation of Hela cells via inhibiting DNA replication and induced apoptosis of Hela cells with morphological changes and accumulation of fragmented DNA. Collectively, these findings suggest that Trpp5 might involve calcium homeostasis contributing to cell proliferation and apoptosis.

Embryos transfer is one of the most critical steps for generating genetically modified mice. Because of the limitations of the current transfer equipment and techniques, such as discharge of freshly transferred embryos and the necessity of sophisticated transfer skills, the success ratio of implantation may not well satisfy the requirements for mass production of high quality animals in the field of genetically modified mice. In this study, we describe a modified embryo transfer pipette with a syringe-like tip that can easily be applied to mouse embryo transfer. Using this improved method, we show that the procedures for mouse embryo implantation are simplified and easier to perform; moreover, the viability rate of mouse embryos is 20% higher than that achieved with conventional methods. Our modified tool and improved transfer technique are effective, time-saving and less invasive, resulting in increased success of embryo transfer.

There is rapid development of CA models for simulation of land use patterns and urban systems recently. Traditional models use the uniform transition rules in large areas or at long times. These models have limitations because they use the same factors and weights in different places or times while these factors and weights vary spatially. This paper presents the method of using dynamic transition rules for producing more reliable urban simulation. The advantages of dynamic transition rules are apparent in this paper. First, it uses different factors and weights in different regions which are consistent with actual urban systems. Second, the main factors can be obtained from the dynamic transition rules in different regions which may produce different urban development patterns. Based on the stepwise logistical regression model, dynamic transition rules were obtained for simulating the evolution of the urban systems in five towns of the Dongguan city from 1988 to 2004. Compared with the general CA model, the simulation precision is improved by using this method. From the factors and weights of dynamic transition rules, three kinds of development patterns were obtained: center development pattern, road development pattern and center-road development pattern.

The resistivity of superconducting Pb-doped Bi–Sr–Ca–Cu–O single crystal, with 2212 structure, has been measured using Montgomery technique. The resistivity, like in other high T c oxide superconductors, shows very strong anisotropic characteristic, with a typical metallic behavior but remains a residual resistivity at T = 0 K in the direction parallel to the a − b plane and a "semiconducting-like" temperature dependence in the c direction. The anisotropy (ρc/ρab) is about 104. But the value of resistivity in a − b plane is larger than that of Bi 2 Sr 2 CaCu 2 O y crystal. This may imply that the Bi–O plane plays an important role in superconductivity in this kind of structure.

The response of a cohesionless seabed deposit to the action of standing waves is examined in detail. The seabed deposit is assumed to be an elasto-plastic material obeying a stress-strain constitutive relation similar to the one proposed by Poorooshasb and Pietruszazck [Soils Fdns26(2), 1-15 (1986)], while the interaction between the solid and liquid phase is considered to follow Darcy's linear law. One important conclusion obtained from this study is to demonstrate the influence of the coefficient of permeability on the susceptibility of the sand mass to liquefy: for high values of permeability even a loose sand mass need not liquefy. This is in direct contrast to the commonly held view that the liquefaction potential is a function, only, of the sand constituency.

Properties of dilute pancake vortices on the surface of ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}\mathrm{Ca}{\mathrm{Cu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ superconductors are investigated by measuring the field, temperature, and time dependencies of the critical current of the surface intrinsic Josephson junctions. It is found that the pinning of the surface vortices has two crossovers over the entire temperature range in the superconducting state. For temperatures below and above $\ensuremath{\sim}20\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, strong collective pinning and weaker point defect pinning are observed, respectively. Further increasing the temperature leads to the depinning of the surface vortices. We find that the depinning of the surface vortices can occur at a much lower temperature than that for the bulk vortices, depending on the surface-layer crystalline perfectness or the density of point defects that have been intentionally introduced experimentally.

Intrinsic Josephson junctions on ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ superconductors are fabricated using an in situ low-temperature cleavage technique, which allows for the fabrication of well-controlled surface ${\mathrm{CuO}}_{2}$ double layers of different doping levels. The low-voltage $I\text{\ensuremath{-}}V$ characteristics and $c$-axis conductivity properties are discussed for both the surface junctions ($D\text{\ensuremath{-}}I\text{\ensuremath{-}}{D}^{\ensuremath{'}}$ type) and inner junctions ($D\text{\ensuremath{-}}I\text{\ensuremath{-}}D$ type) where $D$ denotes a $d$-wave superconductor. Our results show that the experimental data can be satisfactorily described in terms of the theory taking account of the coherent process with a directional tunneling matrix element.

To observe the effect of Qiangshengye liquid on senility retarding in rats.The liquid was orally administrated to rats at doses of 3.3 g.kg-1 and 6.6 g.kg-1, and after Twenty-one days the activity of superoxide dismutase (SOD) in red blood cells and lipid peroxide(LPO) in plasma and in liver were examined respectively by spectrophotometry. Fluorescence polarization was used to evaluate the fluidity of erythrocyte membrane. In addition the anti-fatigue effect of the liquid in mice was detected.The liquid can significantly increase the activity of SOD(P0.05) in red blood cells and decrease the contents of LPO in plasma (P0.05) and in liver(P0.01). The fluidity of erythrocyte membrane was also improved (P0.05).Qiangshengye liquid can antagonize lipid peroxidation and therefore may be used for anti-fatigue and senility retarding purposes.

A synthetic oligonucleotide, HSD-2a, encoding a peptide segment of the extracellular domain of a human sperm membrane protein, YWK-II, was inserted by blunt-end ligation at the EcoRV site in the hypervariable, antigenically determinant region IV of Salmonella flagellin gene fliC (d). The recombinant plasmid (pLS408-H1) was transferred into the nonpathogenic aroA live vaccine Salmonella dublin strain SL5928, which is flagellin-negative. Location of the HSD-2a protein on the surface of the flagella was demonstrated by ELISA and by immunogold-labeling electron microscopy using mouse anti-YWK-II antiserum. A 60 kD protein, corresponding to the chimeric flagellin, was isolated from the recombinant S. dublin and found to contain the expressed HSD-2a peptide determined by Western blot analysis using anti-YWK-II antiserum. The Salmonella strain carrying the recombinant plasmid-pLS408-H1 may thus be a potential source of antifertility vaccine.

Now there are four standardization program under way which are supported and coordinated by Chinese national center for R & D on superconductivity. Ten more domestic institutes were involved in these programs. The first critical current Round Robin Test (RRT) on Ag-sheathed 2223 BSCCO tape was finished with success. A parallel RRT on critical temperature measurement of YBCO thin film was completed and the RRT in series will be taken place. In order to provide more information for TC90/WG4, an comparison on RRR measurement for NbTi composite superconductor by different method was carried out. Moreover, a new work item to standardize the measurement method of microwave surface resistance for oxide superconducting thin film was initiated in China.

Recentl the proximity-effect theory of de Gennes and Werthamer is extended to include a nonzero interface resistance in the calculation of the transition temperature of layered superconductors. In this work, we take account of external magnetic field in the formalism to discuss the perpendicular upper critical field H c ,2 ⊥ of a layered SS ′ system (we set T c , S > T c , S ′ ≥ 0). We show that the interplay among the material and sample parameters can lead to a variety of distinct features in H c ,2 ⊥ ( T ). Clear dimensional crossover is predicted for the SS ′ system with low-resistivity S ′ layers.

Epitaxial Tl 2 Ba 2 CaCu 2 O x (Tl-2212) thin film grain boundary Josephson junctions have been fabricated on 24° SrTiO 3 (STO) bicrystal substates by magnetron sputtering and post-annealing process. The junction characteristics have RSJ-like behavior with V c = I c R n of 95 μV at 95 K. The critical current of the junctions near T c (105K) has a temperature dependence similar to that of SNS type ones. The junctions have been used to form a dc-SQUID, which can operate at temperatures up to 99 K.

Two experiments have been conducted to study radiative heat transfer in lightweight fibrous insulations (LWFI). The spectral extinction coefficients for a commercial LWFI have been measured via transmission measurements, and a guarded hot plate apparatus has been used to measure the radiant heat flux as well as the total heat flux in the insulation. The experimental results are compared with the theoretical values calculated according to the analytical models presented in Part I of this paper. The comparisons reveal that the analytical models are useful in giving representative values for the radiative properties of typical LWFI. However, only qualitative agreements have been obtained for the heat transfer results.

Genomic DNA recombinants were isolated from a library of Balb-C mouse genomic DNA fragments cloned in lambda Ch4A by screening with cDNA derived from 13d foetal liver cell or adult reticulocyte poly A+ RNA. Subsequent screening enabled us to identify non-globin genomic sequences whose expression appeared exclusive to or elevated in erythroid cells. Further analysis of the structure and expression of these sequences was performed using Southern blot and DNA or RNA dot hybridisation analysis. In one recombinant part of the cloned genomic sequence corresponded to an erythroblast specific mRNA identified previously by Affara et al, (5).

The superconducting transition temperature T c of Nb/Cu superlattices has been investigated as a function of layer thickness. The dependence of T c above 300 A layer thickness agrees well with proximity effect theory with no adjustable parameters. Below 300 A, the data in conjunction with current proximity theory shows that T c of Nb decreases with layer thickness. This is interpreted as changes in the electronic density of states due to a decrease in the mean-free path.

Josephson effects in a Y 1 Ba 2 Cu 3 O 7 break junction at 77 K are reported. The I-V characteristics show clear Shapiro steps under microwave radiation and magnetic dependence of the critical current is of the typical Fraunhofer diffraction pattern. Estimate of the magnetic penetration depth is given. Discussions of the I-V curve concerning nonstationary processes are presented.

The temperature and angular dependence of critical fields (${H}_{c}$) have been studied as a function of layer thickness for superconducting Nb/Cu superlattices. For layer thicknesses between 100 and 300 \AA{}, dimensional crossover has been observed in the temperature dependence of ${H}_{c}$. Associated with the crossover we find a change in the angular dependence of ${H}_{c}$ to that given by the effective-mass theory. This is the first time that a relationship has been found between dimensional crossover observed in the temperature dependence and that in the angular dependence of critical fields.

Tunneling studies of artificially prepared Nb-Cu superlattices have been performed. Individual layers were in the range 8--5000 A with total sample thicknesses approx.1..mu..m. The coupling strength 2..delta../kT/sub c/ shows a continuous decrease from values of approx.3.8 (thick layers) appropriate for a strong-coupled superconductor toward the weak-coupled value of approx.3.5 (thin layers). Contrary to earlier theoretical predictions and reports of indirect experimental evidence, we find no evidence for electronic states within the superconducting energy gap. The energies of the Nb longitudinal and transverse acoustic (LA and TA) phonons are found to be unaltered from their bulk values down to layer thicknesses of 32 A. At approx.10 A the TA peak remains unaltered in energy but significantly broadens while the LA peak becomes too broad to measure. These results, in conjunction with earlier Brillouin scattering measurements, imply large changes in the phonon dispersion as a function of layer thickness.

A series of samples with nominal compositions ${\mathrm{La}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Ba}}_{\mathrm{x}}$${\mathrm{Cu}}_{1}$${\mathrm{O}}_{3\mathrm{\ensuremath{-}}\mathrm{y}}$ was prepared by solid-state reaction. The subsolidus phase relation in the CuO-rich region of the La-Ba-Cu-O system has been determined by an x-ray diffraction method. Two ternary compounds were confirmed to exist in the system. The tetragonal or pseudotetragonal phase (${\mathrm{Ba}}_{2\mathrm{\ensuremath{-}}\mathit{z}}$${\mathrm{La}}_{\mathit{z}}$)${\mathrm{La}}_{1}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7+\mathrm{\ensuremath{\delta}}}$ has a wide homogenous phase range from z=0.095 to z=0.578, and a crystal structure closely related to the structure of ${\mathrm{Ba}}_{2}$${\mathrm{YCu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$. Superconductivity of compounds in this system was studied by resistivity and ac susceptibility measurements. The relation between crystal structure and the superconductivity is discussed.

The transition from a positive to a negative temperature coefficient of resistivity (TCR) has been studied in the artificially layered metallic system Nb-Cu. We find the TCR to undergo a rather sudden change in sign from positive to negative as the layer thickness is decreased below approximately 10 A. The temperature dependence of the conductivity in the nonmetallic regime can be explained by localization-type theories, and implies that both localization and Coulomb effects are important in this purely metallic three-dimensional system.