bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructural Effects on Microwave Properties of Low‐Temperature Cofired Ceramic Striplines: Experiments and Modeling
Authors: Jang Jae Hyuk
Published: March 2010

The effect of microstructure on microwave properties of low‐temperature cofired ceramic (LTCC) stripline packages was studied with experiments and simulations. Microstructure was controlled experimentally by modifying organic compositions and heating procedures. Pores existing at the conductor/dielectric interface and inside the conductor line affected the microwave properties, such as the effective dielectric constant (εeff), the effective conductivity (σeff), and the unloaded quality factor (QU) of the stripline packages. The models for simulation were introduced with a finite‐element method using high‐frequency simulation software (HFSS). Simulation results showed that the pores existing at the interface made QU increase by 7%–8% while [alt epsilon]eff decrease by more than 10%. Pores inside the conductor line made σeff and QU decrease. The proposed models and simulation results will contribute to improving future designs and manufacturing of LTCC microwave applications.
La(Sr)FeO3 SOFC Cathodes with Marginal Copper Doping
Authors: Simner Steven P. , Anderson Michael D. , Stevenson Jeffry W.
Published: March 2010

(La0.8Sr0.2)0.98Fe0.98Cu0.02O3−δ can be sintered directly onto YSZ (without the need for a protective ceria interlayer). Though subject to an extended “burn‐in” period (∼200 h), anode‐supported YSZ cells using the Cu‐doped LSF achieve power densities ranging from 1.3 to 1.7 W/cm2 at 750°C and 0.7 V. These cells have also demonstrated 500 h of stable performance. The results are somewhat surprising given that XRD indicates an interaction between (La0.8Sr0.2)0.98Fe0.98‐Cu0.02O3−δ and YSZ resulting in the formation of strontium zirconate and/or monoclinic zirconia. The amount and type of reaction product was found to be dependent on cathode and electrolyte powder precalcination temperatures.
Suppression of Liquid Film Migration and Improvement of Dielectric Properties in Niobium‐Doped Strontium Titanate
Authors: Koo Sang‐Yoon , Lee Gyeong‐Geun , Kang Suk‐Joong L. , Nowotny Janusz , Sorrell Chris
Published: March 2010

In an attempt to improve the dielectric properties of SrTiO3‐based boundary‐layer capacitors (BLCs), the effects of infiltrant composition on the liquid film migration and dielectric properties in 0.2‐mol%‐Nb2O5‐doped SrTiO3 were investigated. Powder compacts were sintered at 1480°C for 5 h in 5H2·95N2 and infiltrated with 80Bi2O3·20(xCaO–(1 –x)BaO) at 1300°C for various times in air. When the value of x was 0, 0.2, 0.7, and 1.0, liquid film migration occurred, which formed a new solid‐solution layer containing solute species. On the other hand, when x= 0.5, no liquid film migration was observed. The effective dielectric constant was the highest in the sample with x= 0.5 (no liquid film migration), and it decreased as the migration distance increased. In addition, the loss tangent was the lowest, <1%, in the sample with x= 0.5. Agreement between the estimated effective dielectric constants and the measured values showed that the suppression of liquid film migration improved the dielectric constant. The agreement further indicated that the prediction of the dielectric constant in SrTiO3‐based BLCs was possible using a two‐layer model with a liquid‐infiltrated layer and a SrTiO3‐based oxidized layer.
Effect of Amount of Boron Doping on Compression Deformation of Fine‐Grained Silicon Carbide at Elevated Temperature
Authors: Shinoda Yutaka , Yoshida Michiyuki , Akatsu Takashi , Wakai Fumihiro
Published: March 2010

The effect of the amount of boron doping in the range of 0 to 1.0 wt% on the high‐temperature deformation of fine‐grained β‐silicon carbide (SiC) was investigated by compression testing. Flow stress at the same grain size increased as the amount of boron doping decreased. The stress exponent increased from 1.3 to 3.4 as the amount of boron doping decreased. The strain rates of undoped SiC were ∼2 orders of magnitude lower than those of 1.0‐wt%‐boron‐doped SiC of the same grain size. The apparent activation energies of SiC doped with 1.0 wt% boron and of undoped SiC were 771 ± 12 and 884 ± 80 kJ/mol, respectively. These results suggest that the actual contribution of grain‐boundary diffusion to the accommodation process of grain‐boundary sliding decreased as the amount of boron doping decreased. Consequently, the apparent contribution of the dislocation glide increased.
Effect of Environment on the Stress‐Rupture Behavior of a Carbon‐Fiber‐Reinforced Silicon Carbide Ceramic Matrix Composite
Authors: Verrilli Michael J. , Opila Elizabeth J. , Calomino Anthony , Kiser J. Douglas
Published: March 2010

Stress‐rupture tests were conducted in air, under vacuum, and in steam‐containing environments to identify the failure modes and degradation mechanisms of a carbon‐fiber‐reinforced silicon carbide (C/SiC) composite at two temperatures, 600° and 1200°C. Stress‐rupture lives in air and steam‐containing environments (50–80% steam with argon) are similar for a stress of 69 MPa at 1200°C. Lives of specimens tested in a 20% steam/argon environment were about twice as long. For tests conducted at 600°C, composite life in 20% steam/argon was 30 times longer than life in air. Thermogravimetric analysis of the carbon fibers was conducted under conditions similar to the stress‐rupture tests. The oxidation rate of the fibers in the various environments correlated with the composite stress‐rupture lives. Examination of the failed specimens indicated that oxidation of the carbon fibers was the primary damage mode for specimens tested in air and steam environments at both temperatures.
Thermodynamic Modeling of the YO1.5–ZrO2 System
Authors: Jacobson Nathan S. , Liu Zi‐Kui , Kaufman Larry , Zhang Fan
Published: March 2010

The YO1.5–ZrO2 system consists of five solid solutions, one liquid solution, and one intermediate compound. A thermodynamic description of this system is developed, which allows calculation of the phase diagram and thermodynamic properties. Two different solution models are used—a neutral species model with YO1.5 and ZrO2 as the components and a charged species model with Y3+, Zr4+, O2−, and vacancies as components. For each model, regular and subregular solution parameters are derived from selected phase equilibrium and thermodynamic data. The neutral species and charged species modeling results are compared.
Sintering Behavior and Properties of Iron‐Rich Glass‐Ceramics
Authors: Karamanov Alexander , Taglieri Giuliana , Pelino Mario
Published: March 2010

Iron‐rich glass‐ceramics were obtained by the sintering of two glass powders, labeled G1 and G2, at heating rates of 5° and 20°C/min followed by an isothermal step in the 850°–1050°C temperature interval. The sintering process was evaluated by the linear shrinkage; the closed porosity was estimated by density measurements; the structure and the morphology of the glass ceramics were observed by scanning electron microscopy. The bending strength, the Young modulus, and Vickers hardness of the glass‐ceramics materials were evaluated. The results showed that the sintering process and morphology of the glass‐ceramics depends on the amount of magnetite and pyroxene formed. With a low percentage of crystal phase formed (25%–30% typical of G1) the structure is characterized by closed porosity; at higher crystallization (45%–50% typical of G2) open porosity is mainly formed. The properties of the glass‐ceramics were not influenced by the heating rate but improved with an increase in the degree of crystallization.
Preparation of b‐Axis‐Oriented MFI Zeolite Thin Films Using Slow Dissolution of Source Material
Authors: Seike Takahiro , Matsuda Motohide , Miyake Michihiro
Published: March 2010

A novel in situ hydrothermal method involving the slow dissolution of silicate glasses as a source material was used to successfully prepare b‐axis‐oriented high‐silica zeolite ZSM‐5 (MFI) thin films.
Electrical and Pyroelectric Properties of Highly (001)‐Oriented (Pb0.76Ca0.24)TiO3 Thin Films Grown by a Sol–Gel Process
Authors: Tang Xin‐Gui , Chan Helen Lai‐Wah
Published: March 2010

Highly (001)‐oriented (Pb0.76Ca0.24)TiO3 (PCT) thin films were grown on Pt/Ti/SiO2/Si substrates using a sol–gel process. The PCT film with a highly (001) orientation showed well‐saturated hysteresis loops at an applied field of 800 kV/cm, with remanent polarization (Pr) and coercive electric field (Ec) values of 23.6 μC/cm2 and 225 kV/cm, respectively. At 100 kHz, the dielectric constant and dielectric loss values of these films were 117 and 0.010, respectively. The leakage‐current density of the PCT film was 6.15 × 10−8A/cm2 at 5 V. The pyroelectric coefficient (p) of the PCT film was measured using a dynamic technique. At room temperature, the p values and figures‐of‐merit (FD) of the PCT film were 185 μC/m2K and 1.79 × 10−5 Pa−0.5, respectively.
P‐Type Carbon Nitride Synthesized by a Gas‐Solid Reaction
Authors: Qiu Yu , Gao Lian
Published: March 2010

Amorphous carbon nitride with high nitrogen content (N/C = 1.14) was first successfully synthesized via a novel gas‐solid reaction between carbon tetrachloride (CCl4) vapor and melamine (C3N6H6) at 600°C under atmospheric pressure. The product has been characterized by X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X‐ray powder diffraction, and simultaneous thermogravimetry‐differential scanning calorimetry. It was revealed that the carbon nitride is sp3‐dominated and the reaction‐driven sp2 to sp3 transformation in the material was proposed. The electrical properties of the material were also investigated, showing high p‐type conductivity.
Tunable Microwave Properties of Barium Titanate‐Based Ferroelectric Glass‐Ceramics
Authors: Kageyama Keisuke , Takahashi Junichi
Published: March 2010

BaTiO3‐based ferroelectric glass‐ceramics with the composition 0.65(Ba1−X SrX)TiO3·0.27SiO2·0.08Al2O3 (X= 0.2–0.6) were fabricated, and their tunable dielectric properties were measured at microwave frequency. Major crystalline phases that precipitated during thermal treatment up to 1000°C were (Ba,Sr)TiO3, Ba2TiSi2O8, and BaAl2Si2O8. The Curie temperatures of the heated bulk samples were successfully tuned near room temperature at the composition between X= 0.2 and 0.3. A thick‐film sample with X= 0.3 showed 27% tunability at 5 GHz under 10 kV/cm bias voltage.
Preparation of α‐Alumina Platelets by Laser Scanning
Authors: Wu Yiquan , Choy Kwang‐Leong , Hench Larry L.
Published: March 2010

A laser scanning with gas jet process was developed to prepare alumina platelets from an alumina powder. When the carbon‐dioxide laser scanned the alumina powdery coatings prepared using an electrospraying technique, the alumina particles were heated to a melting state. The coaxial gas ejection force pushed the melting particles to obtain tabular shape grains that recrystallized into alumina platelets in the subsequent rapid‐cool solidification. The phase and morphologies of powder bed were characterized by XRD and SEM. Results show that only α‐alumina platelets were formed in the scanning process and the average edge length and thickness is 10 μm and 1–2 μm, respectively. Laser processing parameters such as laser energy density, scanning speed, and gas pressure were expected to play a vital role in the melting‐crystallization‐solidification process for obtaining platelike grains from powder beds. The preliminary experiment showed that the laser‐scanning technique could be an effective means of tailoring the morphologies of particles to meet application requirements.
Low‐Temperature Preparation of Anatase and Rutile Layers on Titanium Substrates and Their Ability To Induce in Vitro Apatite Deposition
Authors: Wu Jin‐Ming , Hayakawa Satoshi , Tsuru Kanji , Osaka Akiyoshi
Published: March 2010

Surface modification of titanium and its alloys to induce apatite deposition within a short period is of practical importance in clinical applications. In this study, titanium substrates were treated with hydrogen peroxide solutions at low temperatures to yield titania layers consisting of anatase and rutile. Those titania layers, regardless of the fraction of anatase and rutile, were bioactive to induce deposition of apatite in Kokubo's simulated body fluid within 24 h. The bioactivity was attributed to both the epitaxial effect and the abundant Ti–OH group of the titania layer.
Phase‐Selective Pyrolysis and Pr3+ Luminescence in a YF3–Y2O3 System from a Single‐Source Precursor
Authors: Fujihara Shinobu , Koji Shinnosuke , Kadota Yasuhiro , Kimura Toshio
Published: March 2010

Pr3+‐doped YF3 (orthorhombic), YO0.80F1.40 (orthorhombic), YOF (rhombohedral), and Y2O3 (cubic) films were synthesized on quartz‐glass substrates through pyrolysis of a single‐source trifluoroacetate precursor at temperatures between 400° and 900°C in air. Phase‐selective deposition was achieved by controlling heating temperature and time. YF3, which formed first from the precursor, was transformed to YO0.80F1.40, YOF, and Y2O3. Photoluminescent properties of Pr3+‐doped films were examined using ultraviolet excitation. An intense green photoluminescence was observed in the YOF:Pr3+ film, which was deposited at 700°C, through an efficient charge transfer (O2−–Pr3+) excitation.
Density of Bi2O3–B2O3 Binary Melts
Authors: Hwang Chawon , Fujino Shigeru , Morinaga Kenji
Published: March 2010

The densities of xBi2O3·(100−x)B2O3 binary melts (x= 0–100 mol%) have been measured systematically in the temperature range of 973 to 1373 K using the Archimedean double‐bob method. In addition, the molar volume and coefficient of volume expansion have been determined from these density measurements. The density of melts in the Bi2O3–B2O3 binary system decreased with increasing temperature for all compositions, and increased with increasing Bi2O3 content. The molar volume calculated at 1273 K showed a minimum at around 20–30 mol% Bi2O3. The deviation of molar volume from ideality and the partial molar volumes of B2O3 and Bi2O3 single‐component melts were calculated, and the relationships between these properties and Bi2O3 content were investigated. The Δ(MV) (deviation of molar volume from ideality) was negative in the Bi2O3–B2O3 binary melts and showed a minimum of −7.5 cm3 (−17.3%) at 40 mol% Bi2O3 and 1273 K. The PMV (partial molar volume) of the B2O3 melt decreased with increasing Bi2O3 content, up to 70 mol% Bi2O3, and was constant above 70 mol% Bi2O3. The PMV of the Bi2O3 melt was constant up to 30 mol% B2O3 (considered from the viewpoint of Bi2O3), and then decreased sharply with further addition of B2O3. The coefficient of volume expansion increased sharply up to 20 mol% Bi2O3 and decreased with further addition of Bi2O3 at 1273 K. From this result, it can be inferred that the temperature‐induced structural changes taking place in the melts are greatest at 20 mol% Bi2O3.
Influence of Rare‐Earth Additives on Wear Properties of Hot‐Pressed Silicon Nitride Ceramics under Dry Sliding Conditions
Authors: Hyuga Hideki , Jones Mark I. , Hirao Kiyoshi , Yamauchi Yukihiko
Published: March 2010

The influence of different rare‐earth sintering additives (Y, Yb, Lu) on the wear properties of Si3N4 ceramics was investigated during sliding contact without lubricant. The kind of rare‐earth additives was shown to have a significant effect on the wear behavior for contact sliding under the present testing conditions. Samples sintered with Y2O3 as the sintering additive showed evidence of fracture type wear although this was not observed in samples sintered with Yb2O3 and Lu2O3. These smaller rare earths lead to higher grain boundary bonding strength and superior high‐temperature properties and resulted in higher wear resistance. These results showed that the wear properties of Si3N4 ceramics could be tailored by judicious selection of the sintering additives.
Neutron Thermodiffractometry Study of Calcium Zirconate/Magnesium Oxide Formation in the ZrO2–CaO–MgO System
Authors: Serena Sara , Caballero Angel , Sainz M. Antonia , Convert Pierre , Campo Javier , Turrillas Xavier
Published: March 2010

The reaction process to obtain CaZrO3/MgO specimens in the ZrO2–CaO–MgO system from two mixtures of natural and synthetic raw materials were analyzed by neutron thermodiffractometry; differential thermal analysis–thermogravimetry (DTA‐TG) also was used. The results from the different techniques provided a complete description of the decomposition and reaction process in the samples and proved that high‐temperature neutron diffraction is a powerful tool for analyzing in situ reactions up to 1250°C in both mixtures. In the present work, the evolution of the crystalline phases, the mechanism and temperature of formation of CaZrO3, and the activation energy were properly established in terms of the neutron thermodiffraction study.
Improvement of Mechanical Properties and Corrosion Resistance of Porous β‐SiAlON Ceramics by Low Y2O3 Additions
Authors: Yang Jian‐Feng , Zhang Guo‐Jun , She Ji‐Hong , Ohji Tatsuki , Kanzaki Shuzo
Published: March 2010

Addition of Y2O3 as a sintering additive to porous β‐SiAlON (Si6−zAlzOzN8−z, z= 0.5) ceramics has been investigated for improved mechanical properties. Porous SiAlON ceramics with 0.05–0.15 wt% (500–1500 wppm) Y2O3 were fabricated by pressureless sintering at temperatures of 1700°, 1800°, and 1850°C. The densification, microstructure, and mechanical properties were compared with those of Y2O3‐free ceramics of the same chemical composition. Although this level of Y2O3 addition did not change the phase formation and grain size, the grain bonding appeared to be promoted, and the densification to be enhanced. There was a significant increase in the flexural strength of the SiAlON ceramics relative to the Y2O3‐free counterpart. After exposure in 1M hydrochloric acid solution at 70°C for 120 h, no remarkable weight loss and degradation of the mechanical properties (flexural and compression strength) was observed, which was attributed to the limited grain boundary phase, and with the minor Y2O3 addition the supposed formation of Y‐α‐SiAlON.
Evolution in Microstructural Properties of Cetyltrimethylammonium Bromide‐Templated Mesoporous Tin Oxide upon Thermal Crystallization
Authors: Wu Nae‐Lih , Tung Chien‐Yueh
Published: March 2010

Mesoporous crystalline SnO2 was synthesized using a supermolecule‐templating process, in which cetyltrimethylammonium bromide (CTAB) was introduced into a homogenously peptized tin oxyhydroxide sol, followed by calcination in air. The templated powders were calcined either with or without being subjected to a hexamethyldisilazane (HMDS) pretreatment, and the microstructures were characterized as a function of calcination temperature up to 800°C. Organized mesostructure was initially obtained, and grain growth on calcination was the primary factor that destabilized the mesostructure. Compared with the conventional sol–gel process, the templating process promotes the formation of mesoporosity, enlarges pore volume, and drastically slows grain growth. The HMDS treatment further inhibits grain growth above 400°C. The combination of these processes facilitates formation of fully crystallized mesoporous SnO2 materials with very large surface areas. Fully crystallized mesoporous SnO2 that has a surface area of 220 m2/g has been thus obtained by calcination up to 500°C.
π‐Rotation Faults in Hexagonal BaTiO3
Authors: Wu Yu‐Chuan , Lu Hong‐Yang
Published: March 2010

Planar defects in the metastably retained h‐BaTiO3 exhibiting α‐fringe pattern have been characterized via transmission electron microscopy (TEM). The eligible fault vectors were determined by adopting the invisibility criteria of 2πg·R = 0 or 2nπ augmented by high‐resolution imaging. Three stacking faults, F1, F2, and F3, of the extrinsic nature have been fully analyzed. The eligible fault vectors for faults F1 and F3 contained a basal component respectively of ⅓[0001] and ⅙[0001] and a common prismatic component of ⅓〈10[1‐macr]0〉. However, only three of the 〈10[1‐macr]0〉 vectors are the eligible prismatic component for the fault vectors RF1=⅓[0[1‐macr]11], ⅓[10[1‐macr]1], and ⅓[[1‐macr]101], and RF3=⅙[02[2‐macr]1], ⅙[2[2‐macr]01], and ⅙[[2‐macr]021] that have fulfilled the invisibility criteria. On the other hand, all fault vectors RF21=⅙〈[4‐macr]223〉 for fault F2, containing six vectors of the 〈[2‐macr]110〉 family, is eligible. Unlike the faults of πRF=⅙〈[2‐macr]203〉 found in the D019 intermetallics of Ni3Sn and Co3W, neither fault F1 nor F3 is the π‐rotation type. Fault F2, however, is a π‐rotation fault since a 60°‐rotation clockwise about [0001] has produced another eligible fault vector.
Effect of Aging on Rheological Properties of Lime Putty
Authors: Atzeni Cirillo , Farci Alessio , Floris Deborah , Meloni Paola
Published: March 2010

The increasingly wider application of lime‐based materials for the conservation and restoration of historical buildings has led to a revival of interest in lime putty. One of the most well‐known and highly regarded properties of lime putty is its plasticity/workability.

This paper describes the results of a rheological investigation conducted on putties having identical water content but aged for different times, with the aim of providing an objective and quantitative evaluation of plasticity. Rheological measurements have demonstrated that, all other conditions being equal, shear stress increases with aging. We propose here to consider some parameters derived from Tattersall and Bingham models that can be used as a quantitative measure of plasticity directly correlated with aging.
Abnormal Grain Growth Occurring at the Surface of a Sintered BaTiO3 Specimen
Authors: Chun Jae‐Sun , Hwang Nong‐Moon , Kim Doh‐Yeon , Park Jong‐Keuk
Published: March 2010

When a BaTiO3 powder compact was sintered in air, the abnormal grain growth (AGG) was observed to occur at the surface of the specimen. The BaO evaporation from the surface and consequent formation of eutectic liquid is suggested to be the cause of AGG. When the evaporation of BaO during sintering was prevented by embedding the specimen in the same powder, no AGG was observed to occur.
Sintering of Zirconia Nanopowder by Microwave‐Laser Hybrid Process
Authors: Peelamedu Ramesh , Badzian Andrzej , Roy Rustum , Martukanitz Richard P.
Published: March 2010

A new hybrid sintering process has been developed by replacing all but one laser by microwaves in the existing simultaneous multiple laser process (SIMPLE). Microwave energy has been used to preheat the material before laser radiation, and the synergism between microwave and laser energies could effectively heat the material to temperatures of 1700°C and beyond in just a few minutes. Using this process, rapid sintering of 3Y–ZrO2 (3Y–TZP) pellets has been achieved in a few minutes. Microstructural investigations reveal that the microwave–laser hybrid sintered pellets of 3Y–ZrO2 have nanograins averaging about 20 nm. The microwave–laser hybrid sintering process can clearly be a new approach for fabrication of nanoceramics and nanocomposites.
Low‐Temperature Synthesis of Nanocrystalline α‐Si3N4 Powders by the Reaction of Mg2Si with NH4Cl
Authors: Gu Yunle , Chen Luyang , Qian Yitai
Published: March 2010

Nanocrystalline α‐Si3N4 powders have been prepared with a yield of 93% by the reaction of Mg2Si with NH4Cl in the temperature range of 450° to 600°C in an autoclave. X‐ray diffraction patterns of the products can be indexed as the α‐Si3N4 with the lattice constants a= 7.770 and c= 5.627 Å. X‐ray photoelectron spectroscopy analysis indicates that the composition of the α‐Si3N4 samples has a Si:N ratio of 0.756. Transmission electron microscopy images show that the α‐Si3N4 crystallites prepared at 450°, 500°, and 550°C are particles of about 20, 40, and 70 nm in average, respectively.
The Role of Betamethasone in the Treatment of Acute Exudative Pharyngitis
Authors: Marvez‐Valls Eduardo G. , Ernst Amy A. , Gray Jon , Johnson William D.
Published: March 2010

Abstract. Objective: To compare betamethasone with placebo as an adjuvant to antibiotic therapy in the treatment of acute exudative pharyngitis. Methods: The study was a randomized, doubled‐blind, placebo‐controlled, single‐center, parallel, outpatient clinical trial. After consent was obtained, each patient was asked to rate his or her pain on a 10‐cm numbered visual analog scale (VAS; 0–10). All of the patients received injectable benzathine penicillin. If allergic to penicillin, they were started on a 10‐day course of polyenteric‐coated erythromycin (PCE). Each patient was randomized to receive either IM betamethasone or IM placebo. All patients were contacted by telephone at 24 and 48 hours by one of the study investigators and asked to rate their pain based on another VAS. If their pain was not resolved by 48 hours, they were called again daily between the third and seventh days after the initial visit to determine the time of pain resolution. Results: A total of 92 patients were enrolled in the study, with 46 randomized to receive placebo and 46 to receive betamethasone. Eight patients were excluded from the statistical analysis because of inability to obtain follow‐up. Demographic comparison showed that gender distributions, ages, mean initial pain scores, mean times to the first and second follow‐up calls, and treatment regimens were similar in the 2 groups. There were significantly better pain scores for the betamethasone group at first follow‐up (p = 0.0005), at second follow‐up (p = 0.004), and in number of hours until relief of pain (p = 0.004). When only those patients with a positive culture for a streptococcus species were analyzed, there also were significant reductions in pain score at the first (p = 0.006) and second (p = 0.02) follow‐up visits. Conclusion: Pain relief was greater and more rapid in patients treated with betamethasone as an adjuvant therapy in acute exudative pharyngitis.
Intravenous Ketorolac vs Intravenous Prochlorperazine for the Treatment of Migraine Headaches
Authors: Seim Michael B. , March Juan A. , Dunn Kathleen A.
Published: March 2010

Abstract. Objective: To compare IV ketorolac with IV prochlorperazine as the initial treatment of migraine headaches in the ED. Methods: A prospective, double‐blind comparison study was performed, using a convenience sample of 64 patients suffering from migraine headaches presenting to the ED at a tertiary care university teaching hospital. Patients were randomly assigned to receive either 10 mg of prochlorperazine IV or 30 mg of ketorolac IV. Patients scored the severity of their headaches using a 10‐cm visual analog pain scale. An initial mark was made on the scale at the time of entry into the study and later another mark was made on a new unmarked pain scale 1 hour after medication administration. Changes in pain scores within each treatment group and between groups were analyzed using the Wilcoxon rank sum test. Results: Prior to treatment, the patients assigned to receive prochlorperazine had a median score of 9.2 cm (mean ± SD pain score of 8.3 cm ±2.1 cm), while the patients receiving ketorolac had a median score of 9.0 (mean pain score of 8.4 cm ± 1.7 cm). There was no significant difference between the pain scores of the participants in the 2 groups prior to treatment (p = 0.80). One hour after medication administration, the patients in the prochlorperazine group had a median score of 0.5 cm (mean 2.1 ± 3.2 cm), while those patients receiving ketorolac had a median pain score of 3.9 (mean 4.0 ± 3.3 cm). The decrease in pain score was significant for both groups of patients (p = 0.0001). The change in pain score for the patients in the prochlorperazine group (median 7.1) was significantly greater than the change in pain score for the patients in the ketorolac group (median 4.0; p = 0.04). Conclusion: Although both drugs were associated with a significant reduction in pain scores, benefit over a placebo agent was not tested. Furthermore, the patients who received prochlorperazine IV for migraine headaches had a statistically significant greater decrease in their pain scores than did those receiving ketorolac IV.
Retinal Venous Oxygen Saturation Correlates with Blood Volume
Authors: Denninghoff Kurt R. , Smith MatthewH. , Hillman Lloyd W. , Redden David , Rue Loring W.
Published: March 2010

Abstract. Objectives: To evaluate the sensitivity of retinal venous O2 saturation (SrvO2) for early blood loss and reinfusion. A secondary objective was to measure the correlation between SrvO2 and mixed venous O2 saturation (SvO2) during blood loss and reinfusion. Methods: Seven anesthetized swine were bled at 0.8 mL/kg/min to 16 mL/kg. Shed blood was re‐infused at the same rate and the swine were allowed to equilibrate. After equilibration, repeat hemorrhages were performed at 1.6 mL/kg/min and 2.4 mL/kg/min. SrvO2 was measured using an eye oximeter (EOX) and SvO2 was measured using a fiber‐optic catheter. Results: During blood loss, SrvO2 correlated with blood removed (r= ‐0.88, ‐0.97, ‐0.96) and SvO2 (r= 0.87, 0.98, 0.92). During reinfusion, SrvO2 correlated with blood re‐infused (r= 0.63, 0.76, 0.82) and SvO2 (r= 0.80, 0.93, 0.96). SrvO2 decreased 1.22 ± 0.60%/mL/kg of blood removed. The rate of decrease in SrvO2 per minute (ΔSrvO2) when blood was removed at 2.4 mL/kg/min was significantly greater than ΔSrvO2 when blood was removed at 0.8 mL/kg/ min (p < 0.007). The rates of change in blood pressure (BP) and pulse were not significantly different at any rate of blood removal. Conclusions: In this model, retinal venous O2 saturation correlated with blood volume and central venous O2 saturation. Unlike the rate of change in BP and heart rate, ΔSrvO2 values were significantly different at different rates of blood removal. Use of an EOX to monitor for blood loss, estimate the rate of hemorrhage, and evaluate the response to therapy during resuscitation warrants further study.
An Assessment of Clinical Wound Evaluation Scales
Authors: Quinn James V. , Wells George A.
Published: March 2010

Abstract. Objective: To compare 2 clinical wound scales and to determine a minimal clinically important difference (MCID) on the visual analog cosmesis scale. Methods: Using data from 2 previously published clinical trials, 91 lacerations and 43 surgical incisions were assessed on the 2 scales; a 100‐mm visual analog scale (VAS) (0 = worst possible scar, 100 = best possible scar) and a wound evaluation scale (WES) assessing 6 clinical variables (a score of 6 is considered optimal, while a score of ≤5 suboptimal). All wound assessments on the VAS were done by 2 cosmetic surgeons who rated photographs on 2 occasions. A cohort of wounds on the WES were assessed by a second observer. The difference of the mean optimal and suboptimal VAS scores for each study was used to determine a MCID on the VAS scale. Results: The VAS scale yielded intraobserver agreements of 0.93 and 0.87 (95% CI: 0.89–0.96 and 0.78–0.93) and interobserver agreements of 0.50 and 0.71 (95% CI: 0.32–0.65 and 0.52–0.84) for lacerations and incisions, respectively. Kappa coefficient measuring agreement on the WES was 0.79 (95% CI: 0.57–1.0). The mean (±SD) VAS scores of optimal wounds were 72 ± 12 mm and 65 ± 20 mm, while the mean scores of suboptimal wounds were 57 ± 17 mm and 50 ± 23 mm for lacerations and incisions, respectively. Conclusions: An MCID on the VAS cosmesis scale is 15 mm. Studies should be designed to have a sample size and power to detect this difference.
Advanced Life Support vs Basic Life Support Field Care: An Outcome Study
Authors: Eisen Jeffrey S. , Dubinsky Isser
Published: March 2010

Abstract. Objective: To determine whether the provision of advanced life support (ALS) field care has any impact on patient outcome in the urban Canadian environment. Methods: A convenience cohort study was conducted of all emergent ambulance transfers of adults to an urban Canadian hospital from May 22 to July 31, 1996. Data were collected from ambulance call reports regarding presenting complaint and field interventions applied, and from hospital records regarding time in the ED, hospital length of stay (LOS), and discharge disposition. Patient outcomes were compared within 7 presenting complaint groups (chest pain, altered level of consciousness, shortness of breath, abdominal pain, motor vehicle crash, falls, and other) by field care level: level 1—BLS (basic life support) vs levels 2 and 3— ALS. Results: The study population consisted of 1,397 patients. No significant differences were seen between BLS and ALS patients on baseline demographics. ED triage score did not depend on field care level for any group, implying that those in the ALS group were not inherently sicker. Outcome measures (ED LOS, admission rates, and hospital LOS) showed no significant differences between BLS and ALS for each presenting complaint group. Discharge dispositions were analyzed by x2 but were not varied enough to allow reliable analysis. Observation of trends suggested no difference between BLS and ALS. Conclusions: There was no beneficial impact on the measured patient outcomes found in association with the provision of ALS vs BLS field care in Metropolitan Toronto for patients who were brought to a non‐trauma center.
End‐tidal Carbon Dioxide Monitoring in Emergency Medicine, Part 1: Basic Principles*
Authors: Ward Kevin R. , Yealy Donald M.
Published: March 2010

Abstract. End‐tidal carbon dioxide (PetCO2) monitoring is becoming more common in both the ED and the out‐of‐hospital setting. Its main use has been as an aid when confirming endotracheal intubation. However, since CO2 is intrinsically coupled with states of metabolism, circulation, and ventilation, PetCO2 monitoring along with analysis of its capnographic component is becoming increasingly valuable for other uses in the ED. This article reviews the physiology of CO2, the means by which end‐tidal CO2 may be monitored, and the components and analysis of the capnogram.
The Pattern of Early Lung Parenchymal and Air Space Injury Following Acute Blood Loss
Authors: Younger John G. , Taqi Ali S. , Jost Peter F. , Till Gerd O. , Johnson Kent J. , Stern Susan A. , Hirschl Ronald B.
Published: March 2010

Abstract. Acute lung injury is a frequent clinical occurrence following blood loss and trauma. The nature of this injury remains poorly understood. Objective: To examine the relative parenchymal and intra‐al‐veolar distribution of inflammation in a rat model of hemorrhage and resuscitation. Methods: Rats were anesthetized and subjected to hemorrhage followed by resuscitation with shed blood and saline. Myelo‐peroxidase activity of lung homogenates and cytology of bronchoalveolar lavage fluid were used to measure total lung and intra‐alveolar neutrophil invasion. Extravasation of IV‐administered [125I]‐albumin was used to determine total lung and alveolar permeability. Permeability results were analyzed using their base‐10 logarithmic transformations. Results: 86 animals were studied. Whole‐lung myeloperoxidase activity was increased (control = 0.34 ± 0.16 units, injured = 0.84 ± 0.43 units, p < 0.01), while there was no difference in intra‐alveolar leukocyte counts (injured = 1.85 ± 1.30 times 105mL, control = 2.44 ± 1.75 times 105mL, p = 0.40), suggesting that the cellular component of the injury was more severe in the intravas‐cular and interstitial spaces. There was a strong trend toward increased permeability in the interstitial compartment, and a significant increase in permeability in the intra‐alveolar compartment (whole‐lung permeability: control =—0.27 ± 0.19 units, injured = 0.10 ± 0.55 units, p = 0.06; alveolar permeability: control = ‐2.00 ± 0.47 units, injured = ‐1.32 ± 0.49 units, p < 0.01), suggesting that the loss of integrity to macromolecules was not limited to the interstitium. Conclusion: Hemorrhage and resuscitation resulted in an acute lung injury characterized by extravasation of intravascular protein into both the interstitium and the intra‐alveolar space. Neutrophil invasion of the lung was demonstrable only in the interstitial compartment.
Elder Patients with Closed Head Trauma: A Comparison with Nonelder Patients
Authors: Nagurney J. Tobias , Borczuk Pierre , Thomas Stephen H.
Published: March 2010

Abstract. Objective: Little is known about the circumstances surrounding closed head trauma (CHT) in elders, and how they differ from nonelders. The study objective was to compare the 2 populations for outcome (positive cranial CT scan depicting traumatic injury, or the need for neurosurgery), mechanism of injury, and the value of the neurologic examination to predict a CT scan positive for traumatic injury or the need for neurosurgical intervention. Methods: A retrospective study was conducted by collecting a case series of patients with blunt head trauma who underwent CT scanning, and comparing elder (aged s60 years) with nonelder patients. The setting was the ED of a university‐affiliated Level‐1 trauma center. Results: Twenty percent of the elders and 13% of the nonelders had CT scans positive for traumatic injury, which conferred a risk ratio of 1.58 (95% CI 1.21–2.05). Older women were more at risk for the need for neurosurgery than were younger ones (3.1 vs 0.3%, RR 10.66, 95% CI 1.26–90.46). Among the elders, falls were the dominant mechanism of closed head trauma, followed by motor vehicle collisions (MVCs), then being struck as a pedestrian. In the nonelders, MVCs, falls, and assaults were the most important mechanisms of injury. A focally abnormal neurologic examination imparted an increased risk for both a CT scan positive for traumatic injury (elder 4.39, 95% CI 2.91–6.62; nonelder 7.75, 95% CI 5.53–10.72) and the need for neurosurgery (elder 35.68, 95% CI 4.58–275.89; nonelder 142.58, 95% CI 19.11–1064.22) in both age groups. Conclusions: Significant differences exist between elder and nonelder victims of CHT with respect to mechanisms of trauma and outcomes (CT scan positive for traumatic injury, or the need for neurosurgery).
Sudden‐onset Severe Acute Asthma: Clinical Features and Response to Therapy
Authors: Woodruff Prescott G. , Emond Stephen D. , Singh Anita K. , Jr. Carlos A. Camargo
Published: March 2010

Abstract. Objectives: To characterize patients with sudden onset of severe acute asthma (SAA) and to examine whether this presentation is associated with rapid recovery. Methods: Retrospective cohort study of ED visits to a teaching hospital. Subjects were aged 18–64 years, with SAA (n= 225), denned as initial peak expiratory flow rate (PEFR) ≤40% of predicted. Visits for sudden‐onset SAA (≤3 hours of symptoms) were characterized and multivariate logistic regression was used to examine the association between sudden onset and rapid recovery. Results: Patient visits for sudden‐onset SAA had different triggers as compared with those for the slower‐onset group (p = 0.006). The sudden‐onset patients were less likely to report an upper‐respiratory‐tract infection (17% vs 40%) and more likely to have an unidentifiable trigger (40% vs 19%). In the multivariate logistic regression model, sudden onset was a strong independent predictor of rapid response [odds ratio (OR) 4.3, 95% confidence interval (CI) 1.6–11.6]. Sudden‐onset visits were less likely to lead to admission (23% vs 43%, p = 0.03). Conclusions: These data suggest that different triggers may be involved in sudden‐onset SAA and that sudden onset of symptoms is independently associated with rapid recovery. In their rapid deterioration and rapid response, these subjects share certain characteristics with “sudden asphyxic asthmatics” and may constitute a population suitable for further study of factors contributing to that condition. While these visits led to admission less frequently, prospective studies are necessary to provide information on duration of response and risk for relapse.
Resident Educational Time Study: A Tale of Three Specialties
Authors: Magnusson A. Roy , Hedges Jerris R. , Ashley Pamela , Harper Richard J.
Published: March 2010

Abstract. Objectives: To compare amounts of in‐hos‐pital time use by PGY1 residents during rotations in emergency medicine (EM), internal medicine (IM), and surgery. This article reports the general study methodology and focuses on the educational aspects of residency time use. Methods: A cross‐sectional, observational study of the activities of EM PGY1 residents was performed while the residents were on duty during the 3 specialty rotations. The activities were recorded by an observer using a log with predetermined categories for clinical/service, educational, and personal areas. A time‐blocked, convenience sample of resident shifts was observed for each service rotation. The sample was proportional to the total number of hours for which a PGY1 resident was expected to be in the hospital during a rotation on that service. No attempt was made to sample the same resident at all time periods or on all rotations. Results: Twelve PGY1 residents were observed for a total of 166 hours on surgery, 156 hours on IM, and 120 hours on EM. These hourly amounts were representative of a typical 2‐week span of service on each rotation for the residents. On average, the residents spent 57% of their time on clinical or service‐oriented activities, 24% on educational activities, and 19% on personal activities. The proportions of time devoted to the 3 major areas were similar for the 3 rotations. In all 3 rotations, the largest proportion of time was spent on patient‐focused education (81% to 92% of total educational time). Only 2% to 11% of educational time was devoted to self‐education. Within the patient‐focused education category, proportionately less resident time with faculty occurred on the surgery rotation than on the EM and IM rotations (18% vs 30% and 27%, respectively). Conclusion: The general breakdowns of clinical/service, educational, and personal time use by PGY1 residents are proportionately similar for the 3 service rotations. Patient‐focused education is the primary mode of education for all services. In‐hospital, self‐education time is limited. Clinical teaching is largely by nonfaculty. The educational implications of these findings are discussed.
Rapid Early Action for Coronary Treatment: Rationale, Design, and Baseline Characteristics
Authors: Simons‐Morton Denise G. , Goff David C. , Osganian Stavroula , Goldberg Robert J. , Raczynski James M. , Finnegan John R. , Zapka Jane , Eisenberg Mickey S. , Proschan Michael A. , Feldman Henry A. , Hedges Jerris R. , Luepker Russell V.
Published: March 2010

Abstract. Objectives: Early reperfusion for acute myocardial infarction (AMI) can reduce morbidity and mortality, yet there is often delay in accessing medical care after symptom onset. This report describes the design and baseline characteristics of the Rapid Early Action for Coronary Treatment (REACT) community trial, which is testing community intervention to reduce delay. Methods: Twenty U.S. communities were pair‐matched and randomly assigned within pairs to intervention or comparison. Four months of baseline data collection was followed by an 18‐month intervention of community organization and public, patient, and health professional education. Primary cases were community residents seen in the ED with chest pain, admitted with suspected acute cardiac ischemia, and discharged with a diagnosis related to coronary heart disease. The primary outcome was delay time from symptom onset to ED arrival. Secondary outcomes included delay time in patients with Ml/unstable angina, hospital case‐fatality rate and length of stay, receipt of reperfusion, and ED/emergency medical services utilization. Impact on public and patient knowledge, attitudes, and intentions was measured by telephone interviews. Characteristics of communities and cases and comparability of paired communities at baseline were assessed. Results: Baseline cases are 46% female, 14% minorities, and 73% aged ≥55 years, and paired communities have similar demographics characteristics. Median delay time (available for 72% of cases) is 2.3 hours and does not vary between treatment conditions (p > 0.86). Conclusions: REACT communities approximate the demographic distribution of the United States and there is baseline comparability between the intervention and comparison groups. The REACT trial will provide valuable information for community educational programs to reduce patient delay for AMI symptoms.

ACADEMIC EMERGENCY MEDICINE 1998; 5:726–738
Epidemiology of Alcohol‐related Emergency Department Visits
Authors: Li Guohua , Keyl Penelope M. , Rothman Richard , Chanmugam Arjun , Kelen Gabor D.
Published: March 2010

Abstract. Objective: To examine the population and geographic patterns, patient characteristics, and clinical presentations and outcomes of alcohol‐related ED visits at a national level. Methods: Cross‐sectional data on a probability sample of 21,886 ED visits from the 1995 National Hospital Ambulatory Medical Care Survey were analyzed with consideration of the individual patient visit weight. The annual number and rates of alcohol‐related ED visits were computed based on weighted analysis in relation to demographic characteristics and geographic region. Specific variables of alcohol‐related ED visits examined included demographic and medical characteristics, patient‐reported reasons for visit, and physicians' principal diagnoses. Results: Of the 96.5 million ED visits in 1995, an estimated 2.6 million (2.7%) were related to alcohol abuse. The overall annual rate of alcohol‐related ED visits was 10.0 visits per 1,000 population [95% confidence interval (CI) 8.7–11.3]. Higher rates were found for men (14.7 per 1,000, 95% CI 12.5–16.9), adults aged 25 to 44 years (17.8 per 1,000, 95% CI 15.0–20.6), blacks (18.1 per 1,000, 95% CI 14.0–22.1), and residents living in the northeast region (15.2 per 1,000, 95% CI 12.1–18.2). Patients whose visits were alcohol‐related were more likely than other patients to be uninsured, smokers, or depressive. Alcohol‐related ED visits were 1.6 times as likely as other visits to be injury‐related, and 1.8 times as likely to be rated as “urgent” or “emergent.” The leading principal reasons for alcohol‐related ED visits were complaints of pain, injury, and drinking problems. Alcohol abuse/dependence was the principal diagnosis for 20% of the alcohol‐related visits. Conclusion: Alcohol abuse poses a major burden on the emergency medical care system. The age, gender, and geographic characteristics of alcohol‐related ED visits are consistent with drinking patterns in the general population.