Elimination Of Leakage Research Articles

Record power-added-efficiency, low-voltage GOI (GaAs on insulator) MESFET technology for wireless applications

A record-high power-added efficiency (PAE) is obtained from a GaAs on insulator (GOI) MESFET. Al/sub 2/O/sub 3/ obtained by the wet oxidation of Al/sub 0.98/GaAs in steam is used as the insulating buffer layer. The insulating buffer results in elimination of buffer leakage and enhanced charge control. 0.35-/spl mu/m gate-length GOI MESFETs exhibiting a record PAE of 72% at a drain voltage of 3 V at 4 GHz are demonstrated.

Optimization of Ti and Co Self-Aligned Silicide RTP for 0.10 μm CMOS

ABSTRACTAs CMOS technologies are scaled to 0.10 μm and beyond, self-aligned silicide (salicide) processes find difficult challenges. As junction depths and linewidths are scaled, achieving both low sheet resistance and low contact resistance maintaining low diode leakage becomes increasingly difficult. In this paper we present studies of Ti and Co salicide processes implemented into a 0.10 μm CMOS technology. We show that both for Ti and Co, the optimization of RTP parameters plays a crucial roll in achieving a successful implementation. For Co salicide, optimization of RTP conditions results in elimination of shallow junction leakage (its main scaling problem). Two-step RTP and one-step RTP Ti salicide processes are compared, showing the advantages of one-step RTP. The RTP process windows for low resistance narrow gates (the main scaling issue for Ti salicide) are analyzed. Processes with pre-amorphization, with Mo doping and with a combination of both are compared. An optimal process using Mo and preamorphization implants and one-step RTP is shown to result in excellent device characteristics and low resistance to 0.06 μm gates.

Effect of pH on the preparation of poly-L-lysine-stabilized calcium alginate beads for immobilization of aminoacylase

The preparations of calcium alginate beads stabilized with poly-L-lysine and encapsulating aminoacylase were conducted at different pH conditions. The interaction of poly-L-lysine and alginate beads proceeds readily. The beads prepared at pH 7.0 exhibited high operational and storage stability with the elimination of enzyme leakage and the immobilized aminoacylase possessed high biological activity.

Doubly strained In/sub 0.41/Al/sub 0.59/As/n/sup +/-In/sub 0.65/Ga/sub 0.35/As HFET with high breakdown voltage

An In/sub 0.41/Al/sub 0.59/As/n/sup +/-In/sub 0.65/Ga/sub 0.35/As HFET on InP was designed and fabricated, using the following methodology to enhance device breakdown: a quantum-well channel to introduce electron quantization and increase the effective channel bandgap, a strained In/sub 0.41/Al/sub 0.59/As insulator, and the elimination of parasitic mesa-sidewall gate leakage. The In/sub 0.65/Ga/sub 0.35/As channel is optimally doped to N/sub D/=6*10/sup 18/ cm/sup -3/. The resulting device (L/sub g/=1.9 mu m, W/sub g/=200 mu m) has f/sub t/=14.9 GHz, f/sub max/ in the range of 85 to 101 GHz, MSG=17.6 dB at 12 GHz V/sub B/=12.8 V, and I/sub D(max)/=302 mA/mm. This structure offers the promise of high-voltage applications at high frequencies on InP.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Elimination of mesa-sidewall gate leakage in InAlAs/InGaAs heterostructures by selective sidewall recessing

Conventional mesa isolation in InAlAs/InGaAs HFETs results in the gate coming in contact with the exposed channel at the mesa sidewall, forming a parasitic gate-leakage path. The authors propose a simple method of recessing the channel edge into the mesa sidewall using a succinic-acid-based selective etchant for InGaAs over InAlAs. SEM photographs confirm the recessing of the channel along the sidewall. Special heterostructure diodes, designed with varying amounts of mesa-sidewall/gate-metal overlap, were fabricated with and without the sidewall isolation step. Electrical measurements confirm the complete elimination of sidewall leakage. for both diodes and HFETs. >

Stiff railguns

Stiff guns have been operated with both plasma and solid armatures. A performance gain was seen in the plasma railgun as stiffness was increased. A stiff gun will help to maintain the bore shape and preserve the integrity of the seam between rail and insulator under the extreme asymmetric loads sustained during high-pressure operation. The hydraulically preloaded moly and ceramic gun has been fired six times at pressures as high as 87 ksi, and the bore still holds roughing vacuum up to two hours after the test. The elimination of seam leakage helps control bore erosion associated with plasma reconstitution from the rail and plasma perturbation that might result in loss-initiating instabilities. Reduced rail deflection allows solid and transitioning armatures to track the bore surface. Similar to all plasma armature operation, the stiff gun seals the plasma associated with a transitioning solid armature. The efficiency of transitioning solid armatures increases in a stiff railgun. An analysis of the strain energy associated with the deflection of the railgun structure is presented, and this mechanism is found to be a small fraction of the energy associated with armature loss and the rail resistive loss. The design and scale testing of the next generation of stiff railguns is underway, with the emphasis on reduced weight for field-portability and space-traceability requirements.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Inhibition of Blood-Aqueous Humor Barrier Breakdown With Diclofenac

Various doses of a new topical nonsteroidal anti-inflammatory agent, diclofenac sodium, were tested against prednisolone sodium phosphate in a randomized double-masked study to determine comparative efficacy and safety regarding the reduction of postsurgical ocular inflammation. Inflammation was assessed by measuring fluorescein leakage into the anterior chamber using fluorophotometry techniques. Increased leakage in each patient's operated-on eye compared with the unoperated-on control eye was attributed to a breakdown in the blood-aqueous barrier caused by the cataract surgery. Elimination or significant reduction of fluorescein leakage within a treatment group constituted increased efficacy in controlling inflammation. A total of 124 cases were analyzed. There were no preoperative differences among groups in fluorescein leakage. At 1 week after surgery, all three diclofenac groups had significantly less fluorescein leakage compared with the prednisolone group. Mean percent increases were 56% to 118% in diclofenac groups vs 324% in the prednisolone group. No differences among diclofenac concentrations were detected. The differences between prednisolone and diclofenac were also present, although of lesser magnitude, at 3 weeks. This demonstration of increased efficacy of the nonsteroidal anti-inflammatory agent vs prednisolone is promising given the known side effects of ocular steroids.

Marginal leakage of microfilled composite resin restorations

I nvestigations have shown that marginal leakage is significantly reduced or eliminated in restorations where the cavosurface angle and the enamel are etched and a layer of unfilled resin is placed before and after placement of the restoration.‘-6 -Elimination or reduction of marginal leakage would decrease sensitivity, discoloration, and recurrent caries and thereby result in greater longevity of composite resin restorations.’ Recently, composite resins of different compositions have been introduced to the dental profession. They are known as microfilled composite resins and are designed to give smooth textures of the surface after finishing procedures. The microfilled composite resins have a higher coefficient of thermal expansion than tooth structure and conventional composite resins. Thermal dimensional changes in composite restorations depend on the coefficient of thermal expansion of the composite resins and the size of the restoration. Apparently, to minimize marginal leakage and to maintain marginal integrity, the thermal expansion of composite resin restorations should be similar to that of tooth structure.* This study evaluated the marginal leakage of several microfilled composite resins that have higher coefficients of thermal expansion than tooth structure or the conventional composite resins.

Regression Patterns of Uveal Melanomas after Proton Beam Irradiation

Forty-four uveal melanomas were evaluated for patterns of tumor regression after proton beam irradiation. All tumors were followed for a minimum of ten months after treatment. Seven lesions completely disappeared, 33 have decreased in size, and 4 remained unchanged. Associated signs of tumor regression were: resolution of the secondary serous retinal detachments, central apical yellow discoloration of the tumor, destruction of the tumor’s vasculature, and elimination of fluorescein leakage. This study demonstrated that regression after proton beam irradiation is a relatively slow process, and the effects of radiation could be observed in some cases more than a year after treatment.

Exposure of operating room personnel to anaesthetic agents: an examination of the effectiveness of scavenging systems and the importance of maintenance programs.

Ten Alberta hospitals were monitored to assess the exposure of operating room personnel to nitrous oxide, halothane and enflurane during the average work day. Exposure to these agents in operating rooms without scavenging systems was determined to be well above the recommended guidelines. Contaminants were significantly lower in operating rooms with scavenging systems of either the wall suction type or the air-conditioning exhaust type. In the majority of studies, leakage points of anaesthetic gases were found throughout the anaesthesia systems. Where maintenance programs for the anaesthesia equipment were designed for the detection and elimination of leakage, contaminant levels were significantly lower than in those hospitals where the maintenance programs were concerned solely with proper equipment function as it relates to patient care. A regular, frequent maintenance program for all anaesthesia and scavenging systems designed to identify and correct leakage points is therefore recommended. We consider a nitrous oxide monitor to be the ideal tool for detection of leakage.

A safer and more reliable operative technique for esophageal reconstruction using a gastric tube

A safer and more reliable method of esophageal reconstruction, using a gastric tube, is described. The procedure to create an elongated gastric tube involves separate cutting of the seromuscular and mucosal layer along the line extending parallel to and 4 cm from the greater curvature of the stomach. The end of the cervical esophagus is anastomosed to the posterior wall of the gastric tube in end-to-side fashion. In addition, circumferential cutting of the seromuscular layer of the gastric tube about 5 cm from the anastomotic line is performed to avoid tension resulting from postoperative shrinkage of the gastric tube due to muscle contraction. Combination of these methods resulted in complete elimination of anastomotic leakage.

Proton irradiation of choroidal melanomas. Preliminary results.

Choroidal malignant melanomas in nine patients were treated with proton beam irradiation at the Harvard Cyclotron Laboratory, Cambridge, Mass. Each patient received five proton beam treatments in eight to ten days, totalling 4,730 to 8,570 rads at the tumor. No complications occurred during the treatment or follow-up period, which, at the time of this writing, ranges from one to 24 months, with an average of 12 months. No further growth of the tumor has been observed in any patient. Different signs of tumor regression have been noted. Resolution of the serous retinal detachments that accompanied some tumors is the earliest finding. Pigment changes over the surface of the tumor and adjacent pigment epithelium is a usual initial tumor response. Fluorescein angiography initially showed decreased leakage of dye; later, destruction of the tumor's vasculature and elimination of fluorescein leakage became evident. Only large choroidal vessels remained patient. Ultrasonography revealed decreased height of the tumors postirradiation, and the radioactive phosphorus (32P) uptake test, repeated in one patient, turned negative on postirradiation measurements.

Approximating the Exact Finite Sample Distribution of a Spectral Estimator

In this paper an explicit and computationally convenient expansion of the exact finite sample distribution function of a quasi-maximum likelihood spectral estimator is given. In the majority of practical situations it will be necessary to estimate certain nuisance parameters of the distribution. Therefore, a method of evaluating these parameters is suggested and some Monte-Carlo evidence concerning the practical implementation of the results is given. 1 INTRODUCTfON AN EXTENSIVE SET of asymptotic results relating complex statistical analysis to the problems that arise in estimating spectra from the discrete Fourier transforms of time series data has been well established; see, for example, Brillinger [3] and Goodman [6]; and Hannan [11] has recently extended these results to cover the modified Fourier coefficients, proposed by Bingham, Godfrey, and Tukey [1] and defined in (2.3) below. Unfortunately it seems likely that the sample sizes required for one to approach the asymptotic position will not be available when considering the analysis of many economic time series. In a recent article, however, Hatanaka [12] has shown that the elimination of leakage produced by the modified Fourier coefficients is effective for small finite realizations and that it may be possible to recover the loss of degrees of freedom associated with the familiar estimator obtained by averaging over the modified periodogram.2 The purpose of the present paper is to extend these results by using complex statistical analysis to derive expressions for both the form and exact finite sample distribution of a spectral estimator obtained from the modified Fourier coefficients. Thus in the following section a brief exposition of some basic theory is given and a quasi-maximum likelihood estimation procedure is suggested. In Section 3 an exact expression for the finite sample distribution of the proposed estimator is given and shown to incorporate an established distributional result as a particular special case. In the majority of practical situations it will be necessary to estimate certain nuisance parameters of this distribution if it is to be employed and a method of evaluating these parameters is also suggested. It is well known, however, that while the replacement of nuisance parameters by consistent estimates will generally leave asymptotic theory intact the consequences of estimating nuisance parameters are unlikely to be negligible in finite sample theory. Since it is not possible to determine analytically the effect that the estimation of these nuisance parameters will have, the results of some simple Monte-Carlo

The mechanical aspects of anesthetic pollution control.

Reduction of anesthetic contamination in the operating room requires removal of excess circuit gases (scavenging), elimination of anesthetic equipment leakage, and avoidance of anesthetic technics which allow unopposed spill of gas into the operating room. Scavenging and disposal of excess anesthetic gases can present hazards to the patient; means to protect the breathing circuit from elevated positive and negative pressures should be of prime consideration in selecting a scavenging system. Leakage from anesthic equipment occurs in the high-pressure (central and tank N2O sources to the machine flowmeters) and the low-pressure portions (from the machine flow-meters to the patient) of the system and can be of sufficient magnitude to virtually negate effective scavenging. These leakage points can be readily detected and corrected using periodic simple test procedures.

Grouting Deep Solution Channels Under an Earth Fill Dam

Stabilization of foundation by grouting and elimination of leakage caused by deep limestone solution channels under elliptical earth fill dam which forms pond for log storage at Bowaters Southern Paper Corp newsprint mill at Calhoun, Tenn; because of large size of cavitations, economical considerations indicated use of clay-cement mixture.

Apparatus for the Photo-Electric Measurement of Submarine Illumination assembled for the U.S.A. Research Ship Atlantis

Shelford and Gail (1922) first used photo-electric cells for submarine photometry in the Puget Sound. Poole (1925) produced an apparatus which was suitable for use on small ships in the open sea. This apparatus was used near Plymouth by Poole and Atkins (1926, 1928, 1929) with various minor alterations in design which rendered it more reliable and less subject to errors due to electrical leakage. The object of these researches was to study illumination in relation to photosynthesis, but Russell perceived their bearing on his own work on the phototropic movements of the zooplankton. When considering the research programme of the Atlantis, Dr. George L. Clarke decided that it would be of value to carry out photo-electric measurements of submarine illuminations in connection with his work on vertical distribution of the plankton. A request was accordingly made by Dr. H. B. Bigelow, Director of the Wood's Hole Oceanographic Institute, that such an apparatus should be assembled under our direction. The apparatus here described has been constructed closely upon the lines of H. H. Poole's original apparatus as modified in 1928. Special attention, however, has been given to the elimination of electrical leakage. Furthermore, J. H. J. Poole (1928) devised an apparatus in which rate of flash of a neon lamp was used to measure light. This rate of flash method is one of integration and not an instantaneous measurement as is that of H. H. Poole. The value of the neon lamp method lies in the fact that light under the water is extremely variable near the surface owing to the motion of the waves. This method of measuring under-water illumination was used in Lough Bray, Co. Dublin, by J. H. J. and H. H. Poole (1930), and has since been used at sea by Poole and Atkins (1931). It seemed advisable to include a neon lamp photometer in the outfit so that errors in determining the loss of light on entering the water might be minimised.