CMOS fully digital integrated pressure sensors

Most commercially available silicon pressure transducers are based on a Wheatstone bridge configuration and given an analogue output signal. These devices are generally very sensitive to noise and require complicated circuits (by using passive components) for temperature and non-linearity compensation. This limits the transducer accuracy and increases the calibration cost. To overcome these problems, a new generation of pressure transducers with digital output, based on MOSFET ring oscillators, has been developed. A fully digital integrated pressure sensor and data-acquisition procedures will be presented.     

Simultaneous monitoring of the transport of anions and cations across polypyrrole based composite membranes

A mechanism for the macroscopic charge balance during the transport of anions and cations across polypyrrole based composite membranes is proposed. For the mechanism to be studied, anions and cations were monitored simultaneously across PPy based composite membranes, which are known to have cation exchange (PPy(PSS)), anion exchange (PPy(ClO₄)) and mixed ion exchange properties (PPy(pTS)). Even though none of the membranes were found to be completely permselective, the flux of cations was higher than that of anions across the PPy(PSS) composite membrane, while the flux of anions was higher than that of cations across the PPy(ClO₄) composite membrane. Distinct changes in pH of the receiving solution were also observed. These were a decrease in pH when a predominantly anion exchanging polypyrrole composite membrane was used, and an increase in pH when a membrane that maintains charge balance principally by cation exchange was used. When membranes which display approximately equal permeability towards anions and cations were used the pH of the receiving solution was ca. 6–8. There was only a negligible flux of Ca²⁺ across the PPy(PSS) membrane in the transport experiments carried out with the source solution consisting of either Ca(NO₃)₂ or an equimolar mixture of KNO₃ and Ca(NO₃)₂. The PPy(PSS) composite membrane was impermeable towards NO₃⁻ ions when the source solution was Ca(NO₃)₂ but permeability towards NO₃⁻ was observed when the source solution was either KNO₃ or an equimolar mixture of KNO₃ and Ca(NO₃)₂.     

Laboratory-scale apparatus for the characterization of gas-phase dioxin adsorption

Zeolites are reported as selective adsorbents for the preconcentration of dioxin congeners for emission monitoring at stationary sources. This article involves the development of a laboratory-scale apparatus to characterize gas-phase dioxin adsorption on zeolites and thermal desorption. The laboratory-scale apparatus prepared stable levels of dioxin in a nitrogen flow and in-line adsorption/thermal desorption coupled to a gas chromatograph–mass spectrometer. The apparatus takes into account the low-volatility of the dioxins for their transport in the carrier gas and the possible high temperatures used for zeolite desorption. The apparatus functionalities, such as in-line concentration measurement by a sampling loop and gas chromatograph–mass spectrometer and breakthrough measurement during in-line adsorption, were validated. The generator delivers a stable 2,3-dichlorodibenzo-p-dioxin concentration of 304 ± 6 µg/m³ over 20 days. Two methods, weighing a vial and mass analysis of the sampling loop, were employed for measuring the concentration provided results that were in good agreement. Preliminary gas-phase adsorption experiments have been carried out without any memoryw effects in the valves and transfer lines. The dioxin concentration generated and large diameter of the beads led to low adsorption efficiency of dioxin on FAU13X Na-type zeolites due to a low micropore accessibility.     

Intermittent complete vascular exclusion of the liver during hepatectomy: technique and indications

BACKGROUND/AIMS: Complete intermittent vascular exclusion of the liver (IVEL) combines clamping of the hepatic pedicle with clamping of the hepatic veins without interruption of the caval flow. The major advantages of this technique are that patient preclamping fluid overload is avoided, major haemodynamic changes due to caval clamping are escaped, and it allows a very long clamping time. Disadvantage of this technique is the necessity of looping the terminal part of the hepatic veins. METHODOLOGY: In this prospective study, 41 cases of IVEL (Representing 19% of the hepatectomies carried out for cancer during the same period) used for difficult hepatectomies were analyzed, and the operative technique is presented. RESULTS: IVEL was feasible in 90% of the 46 attempted cases, and completely controlled the bleeding in 90% of the cases. The mean duration of IVEL was 69.2 minutes (Range: 37 to 140), and was greater than 130 minutes in three patients. No liver failure occurred during the postoperative course. CONCLUSION: We conclude that IVEL without caval clamping is a new, and valuable, technique of vascular exclusion of the liver. Its application is indicated in the following conditions: 1. For patients who should have classical vascular exclusion but cannot tolerate vena cava clamping (18% of the cases), 2. for patients with pathological liver parenchyma when intrahepatic venous pressure is high, 3. for patients with impaired liver parenchyma, requiring conservative surgery that leads to anatomic or non-anatomic resection close to a vein (Example: A tumor located in the dihedral angle of the terminal part of two hepatic veins), 4. for patients with tumors closely located to a hepatic vein that must be preserved and sharply dissected (Example: A left trisegmentectomy that requires pelting of the right hepatic vein), and 5. for the scarce patient with tumors infiltrating the major hepatic veins, constraining a hepatic vein reconstruction to preserve liver function.     

Kinetics and Mechanism of the Reduction of Nickel Oxide in Aligned Nickel Oxide-Zirconia and Nickel Oxide-Yttria Eutectic Structures

Unidirectional solidification experiments were carried out at the eutectic composition of the systems NiO-ZrO₂ and NiO-Y₂O₃, yielding materials made of regularly aligned lamellar structures. Eutectic samples were submitted to a chemical reduction treatment at 1075°C under CO/CO₂ mix tures corresponding to Po ₂ values for which only NiO should be reduced to the metal. The rapid formation of nickel be tween the zirconia or yttria platelets and the morphology of the nickel layer resulting from reduction establish that the reduction kinetics were controlled predominantly by the dif fusion of CO to the Ni/NiO interface through the porous Ni product. Experimental data of the variation of reduction depth of NiO as a function of time are qualitatively inter preted using a simple model of interdiffusion of CO in N₂/ CO/CO₂ mixtures. This model also explains the observation of an influence of the dilution of CO on the reduction depth.     

Combined spectroscopic ellipsometry and attenuated total reflection analyses of Al2O3/HfO2 nanolaminates

The microstructure of thin HfO₂-Al₂O₃ nanolaminate high κ dielectric stacks grown by atomic vapor deposition has been studied by attenuated total reflection spectroscopy (ATR) and 8 eV spectroscopic ellipsometry (SE). The presence of Al₂O₃ below HfO₂ prevents the crystallisation of HfO₂ if an appropriate thickness is used, which depends on the HfO₂ thickness. A thicker Al₂O₃ is required for thicker HfO₂ layers. If crystallisation does occur, we show that the HfO₂ signature in both ATR and 8 eV SE spectra allows the detection of monoclinic crystallites embedded in an amorphous phase.     

Improved electrical properties using SrTiO3/Y2O3 bilayer dielectrics for MIM capacitor applications

In this paper, we show that the capacitance–voltage linearity of MIM structures can be enhanced using SrTiO₃ (STO)/Y₂O₃ dielectric bilayers. The C(V) linearity is significantly improved by combining two dielectric materials with opposite permittivity-voltage responses. Three STO/Y₂O₃ stacks with different thicknesses were realized and compared to a 20 nm STO single layer structure. We observed that an increase in the Y₂O₃ thickness leads to an improvement in the voltage linearity, while maintaining an overall capacitance density greater than 10 fF/μm².     

Silhouettes elicit alarm calls from captive vervet monkeys (Cercopithecus aethiops).

In Part 1, alarm calls produced by captive vervets in response to naturally occurring stimuli were analyzed. Females and juveniles regularly alarm called to airplanes, birds, and barking dogs. Juvenile females accounted for 60% of these alarm calls. In Part 2, several monkeys from the colony were isolated and presented with life-sized silhouettes of a leopard, snake, eagle, baboon, vervet, and goose. Adult monkeys alarm called more than did juveniles. Alarm calls were elicited by leopard, snake, baboon, and vervet silhouettes, but none were elicited by eagle or goose silhouettes. Some leopard and snake alarm calls matched those recorded in the wild in the context of the vervets' natural predators. Results indicate that silhouette stimuli are a useful technique for eliciting monkey vocalizations in the laboratory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Response to Grzesiak on rehabilitation psychology.

It was with some chagrin that we read Grzesiak's "Psychology Services in Rehabilitation Medicine: Clinical Aspects of Rehabilitation Psychology" in the August 1979 issue of Professional Psychology (see record 1980-33168-001). In his article, Dr. Grzesiak focuses basically on in-hospital coping and adjustment to disability--hardly a reflection of the holistic approach he mentions. Further, although he correctly points out that psychological tests should be applied on an individual basis and that results should be carefully interpreted, he might have included a discussion of the measurement and evaluative tools that have been developed and utilized in the rehabilitation counseling field. Dr. Grzesiak's relegation of rehabilitation counseling to technician status serves as a further example of his narrow perspective. It is disturbing that such a narrow view as Grzesiak's should be presented in a special issue devoted to the psychologist's role in health care. (PsycINFO Database Record (c) 2010 APA, all rights reserved)