WATER MOVEMENT IN STIFF-MUD WARE AND ITS RELATION TO DRYING*

Stiff-mud test bars were dried from one surface, and the rate of water loss was determined by frequent weighings. The plotted curves indicate an end point in the water movement with a loss of around 60% of the total water. This loss was checked by soluble salts in the clay and alkalinity tests at intervals.     

A LABORATORY EQUIPMENT FOR STIFF-MUD TESTS,INCLUDING EXHAUSTION OF THE AIR1

A small auger machine is described for laboratory use in testing stiff-mud clays with special reference to de-airing the clays and for investigation of augers, dies, and various devices which affect the flow of stiff-mud clay.     

An all-implanted, self-aligned, GaAs JFET with a nonalloyedW/p+-GaAs ohmic gate contact

We describe a self-aligned, refractory metal gate contact, enhancement mode, GaAs junction field effect transistor (JFET) where all impurity doping was done by ion implantation. Processing conditions are presented for realizing a high gate turn-on voltage (~1.0 V at 1 mA/mm of gate current) relative to GaAs MESFET's. The high gate turn-on voltage is the result of optimizing the p⁺-gate implant and anneal to achieve a nonalloyed ohmic contact between the implanted p⁺-GaAs and the sputter deposited tungsten gate contact. Initial nominally 1.0 μm×50 μm n-JFET's have a transconductance of 85 mS/mm and f_t of 11.4 GHz     

Fermi-level pinning at the polysilicon/metal oxide interface-Part I

We report here that Fermi pinning at the polysilicon/metal oxide interface causes high threshold voltages in MOSFET devices. Results indicate that pinning occurs due to the interfacial Si-Hf and Si-O-Al bonds for HfO/sub 2/ and Al/sub 2/O/sub 3/, respectively. Oxygen vacancies at polysilicon/HfO/sub 2/ interfaces also lead to Fermi pinning. We show that this fundamental characteristic affects the observed polysilicon depletion. In Part I, the theoretical background is reviewed and the impact of the different gate stack regions are separated out by investigating the relative threshold voltage shifts of devices with Hf-based dielectrics. The effects of the interfacial bonding are examined in Part II.     

Vertical scaling of temperature,wind and humidity fluctuations: dropsondes from 13 km to the surface of the Pacific Ocean

Observational data were taken in the ‘vertical’ structure at 2 Hz from research dropsondes for temperature, wind speed and relative humidity during the ～800 s it takes to reach the surface from the ～13 km altitude of the National Oceanic and Atmospheric Administration (NOAA) Gulfstream 4SP aircraft. The observations were made mainly through the depth of the troposphere above the eastern Pacific Ocean from 15° N to 43° N (dropsondes) and 60° N (aircraft) in 2004. Grand averages of some key figures and of probability distribution functions (PDFs) were formed by compounding the data from the Winter Storms Projects 2004, 2005 and 2006, comprising 246, 324 and 315 (some dropped up to 60° N) useable sondes, respectively. This sizeable data set was used to representatively characterize the statistical fluctuations in the ‘vertical’ structure from 13 km to the surface. The fluctuations are resolved at 5–10 m altitude, so covering up to 3 orders of magnitude of typical tropospheric weighting functions for passive remote sounders. Average ‘vertical’ statistical, multifractal, scaling exponents H, C ₁ and α of temperature, wind speed and humidity fluctuations observed at high resolution were computed and are available as potential generators of representative, scale-invariant summaries of the vertical structure of the marine troposphere, for use in design and retrieval of remotely sounded observations.     

Simultaneous Modification of Bottom‐Contact Electrode and Dielectric Surfaces for Organic Thin‐Film Transistors Through Single‐Component Spin‐Cast Monolayers

An efficient process is developed by spin‐coating a single‐component, self‐assembled monolayer (SAM) to simultaneously modify the bottom‐contact electrode and dielectric surfaces of organic thin‐film transistors (OTFTs). This effi cient interface modifi cation is achieved using n‐alkyl phosphonic acid based SAMs to prime silver bottom‐contacts and hafnium oxide (HfO₂) dielectrics in low‐voltage OTFTs. Surface characterization using near edge X‐ray absorption fi ne structure (NEXAFS) spectroscopy, X‐ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy, atomic force microscopy (AFM), and spectroscopic ellipsometry suggest this process yields structurally well‐defi ned phosphonate SAMs on both metal and oxide surfaces. Rational selection of the alkyl length of the SAM leads to greatly enhanced performance for both n‐channel (C₆₀) and p‐channel (pentacene) based OTFTs. Specifi cally, SAMs of n‐octylphos‐phonic acid (OPA) provide both low‐contact resistance at the bottom‐contact electrodes and excellent interfacial properties for compact semiconductor grain growth with high carrier mobilities. OTFTs based on OPA modifi ed silver electrode/HfO₂ dielectric bottom‐contact structures can be operated using < 3V with low contact resistance (down to 700 Ohm‐cm), low subthreshold swing (as low as 75 mV dec^?1), high on/off current ratios of 107, and charge carrier mobilities as high as 4.6 and 0.8 cm² V^?1 s^?1, for C60 and pentacene, respectively. These results demonstrate that this is a simple and efficient process for improving the performance of bottom‐contact OTFTs.     

Online volatile organic compound measurements using a newly developed proton-transfer ion-trap mass spectrometry instrument during New England Air Quality Study--Intercontinental Transport and Chemical Transformation 2004: performance, intercomparison, and compound identification

We have used a newly developed proton-transfer ion-trap mass spectrometry (PIT-MS) instrument for online trace gas analysis of volatile organic compounds (VOCs) during the 2004 New England Air Quality Study-Intercontinental Transport and Chemical Transformation study. The PIT-MS instrument uses proton-transfer reactions with H3O+ ions to ionize VOCs, similarto a PTR-MS (proton-transfer reaction mass spectrometry) instrument but uses an ion trap mass spectrometer to analyze the product ions. The advantages of an ion trap are the improved identification of VOCs and a near 100% duty cycle. During the experiment, the PIT-MS instrument had a detection limit between 0.05 and 0.3 pbbv (S/N = 3 (signal-to-noise ratio)) for 2-min integration time for most tested VOCs. PIT-MS was used for ambient air measurements onboard a research ship and agreed well with a gas chromatography mass spectrometer). The comparison included oxygenated VOCs, aromatic compounds, and others such as isoprene, monoterpenes, acetonitrile, and dimethyl sulfide. Automated collision-induced dissociation measurements were used to determine the contributions of acetone and propanal to the measured signal at 59 amu; both species are detected at this mass and are thus indistinguishable in conventional PTR-MS.     

Effect of a controlled high-fat versus low-fat diet on insulin sensitivity and leptin levels in African-American and Caucasian women

Subjective interpretation of dobutamine echocardiograms provides only moderate interinstitutional observer agreement if nonunified data acquisition and assessment criteria are applied. The present study was undertaken to evaluate parameters associated with low interinstitutional observer agreement in the interpretation of dobutamine echocardiograms and to analyze whether standardized interpretation criteria improve interinstitutional observer agreement. One hundred fifty dobutamine echocardiograms (dobutamine up to 40 microg/kg/min body weight and atropine up to 1 mg) were evaluated at 5 centers. Clinical, procedural, and echocardiographic parameters were included in the analysis of variables with significant impact on interinstitutional agreement. Standardized interpretative criteria were established, and 90 dobutamine echocardiograms were reanalyzed by 3 observers using a standardized image display. Multivariate analysis demonstrated low image quality (odds ratio [OR] 0.19, 95% confidence interval [CI] 0.08 to 0.45, p=0.0002), low severity of induced wall motion abnormality (OR 0.17, 95% CI 0.07 to 0.40, p <0.0001), and a low peak rate-pressure product (OR 0.93, 95% CI 0.43 to 2.27, p=0.0382) to result in a low interinstitutional agreement. Standardization of image display in cine loop format and of dobutamine stress echo interpretation criteria resulted in improvement in test result categorization as normal or abnormal, with a kappa value of 0.50, compared with 0.39 using the original subjective interpretation. In conclusion, image quality, the severity of induced wall motion abnormalities, and the obtained rate-pressure product have a significant impact on the interpretation homogeneity of dobutamine echocardiograms. Standardization of image display in cine loop format and of reading criteria results in improved interinstitutional agreement in interpretation of stress echocardiograms.     

Demonstration of npn InAs bipolar transistors with inverted basedoping

We demonstrate np⁺n InAs bipolar transistors that operate under room temperature and cryogenic conditions. InAs transistors on an InP substrate were characterized as a function of temperature and exhibited good room temperature and low temperature common-emitter characteristics. Although the base doping density exceeded the emitter doping density by a factor of 20, current gains of 30 were achieved at room temperature. Junction leakage currents and contact resistance were identified as problems to address