Optimization of Cathode Functional Layers of Solid Oxide Electrolysis Cells.

Sluggish CO2 reduction on the cathodes of solid oxide electrolysis cells greatly affects electrolysis performance. However, there is no study systematically investigating the cathode functional layer (CFL), where the reduction occurs. Cathode supports equipped with fast gas diffusion channels were employed as a platform to investigate the CFL, including porosity, NiO/(Y2O3)0.08Zr0.92O2 (YSZ) ratio, and thickness. The porosity was adjusted by pore former content, and a higher porosity generated a higher electrolysis current density, while the porosity improvement is limited by the fabrication process. The three-dimensional microstructure of the CFL with different NiO/YSZ ratios was reconstructed by distance correlation functions to estimate three-phase boundary density, which can explain the optimal NiO/YSZ weight ratio of 60:40 for CO2 electrolysis. Increasing CFL thickness can provide more active sites until the optimal thickness of 35 µm. Further increasing the thickness results in gas diffusion limitation. Based on the channeled cathode supports, the CFL was optimized according to CO2 electrolysis performance.

Stabilization of volatile Ti(BH4)3 by nano-confinement in a metal-organic framework.

Liquid complex hydrides are a new class of hydrogen storage materials with several advantages over solid hydrides, e.g. they are flexible in shape, they are a flowing fluid and their convective properties facilitate heat transport. The physical and chemical properties of a gaseous hydride change when the molecules are adsorbed on a material with a large specific surface area, due to the interaction of the adsorbate with the surface of the host material and the reduced number of collisions between the hydride molecules. In this paper we report the synthesis and stabilization of gaseous Ti(BH4)3. The compound was successfully stabilized through adsorption in nanocavities. Ti(BH4)3, upon synthesis in its pure form, spontaneously and rapidly decomposes into diborane and titanium hydride at room temperature in an inert gas, e.g. argon. Ti(BH4)3 adsorbed in the cavities of a metal organic framework is stable for several months at ambient temperature and remains stable up to 350 K under vacuum. The adsorbed Ti(BH4)3 reaches approximately twice the density of the gas phase. The specific surface area (BET, N2 adsorption) of the MOF decreased from 1200 m2 g-1 to 770 m2 g-1 upon Ti(BH4)3 adsorption.

Complex transition metal hydrides: linear correlation of countercation electronegativity versus T-D bond lengths.

For homoleptic 18-electron complex hydrides, an inverse linear correlation has been established between the T-deuterium bond length (T = Fe, Co, Ni) and the average electronegativity of the metal countercations. This relationship can be further employed towards aiding structural solutions and predicting physical properties of novel complex transition metal hydrides.

KOH catalysed preparation of activated carbon aerogels for dye adsorption.

Organic carbon aerogels (CAs) were prepared by a sol-gel method from polymerisation of resorcinol, furfural, and hexamethylenetetramine catalysed by KOH at around pH 9 using ambient pressure drying. The effect of KOH in the sol-gel on CA synthesis was studied. It was found that addition of KOH prior to the sol-gel polymerisation process improved thermal stability of the gel, prevented the crystallinity of the gel to graphite, increased the microporosity of CA and promoted activation of CA. The CAs prepared using the KOH catalyst exhibited higher porosity than uncatalysed prepared samples. Activation in CO(2) at higher temperature also enhanced the porosity of CAs. Adsorption tests indicated that the CAs were effective for both basic and acid dye adsorption and the adsorption increased with increasing surface area and pore volume. The kinetic adsorption of dyes was diffusion control and could be described by the second-order kinetic model. The equilibrium adsorption of dyes was higher than activated carbon.

Preparation, microstructure and hydrogen sorption properties of nanoporous carbon aerogels under ambient drying.

Organic aerogels are prepared by the sol-gel method from polymerization of resorcinol with furfural. These aerogels are further carbonized in nitrogen in order to obtain their corresponding carbon aerogels (CA); a sample which was carbonized at 900 °C was also activated in a carbon dioxide atmosphere at 900 °C. The chemical reaction mechanism and optimum synthesis conditions are investigated by means of Fourier transform infrared spectroscopy and thermoanalyses (thermogravimetric/differential thermal analyses) with a focus on the sol-gel process. The carbon aerogels were investigated with respect to their microstructures, using small angle x-ray scattering (SAXS), transmission electron microscopy (TEM) and nitrogen adsorption measurements at 77 K. SAXS studies showed that micropores with a radius of gyration of <0.35 ± 0.07 to 0.55 ± 0.05 nm were present, and TEM measurements and nitrogen adsorption showed that larger mesopores were also present. Hydrogen storage properties of the CA were also investigated. An activated sample with a Brunauer-Emmett-Teller surface area of 1539 ± 20 m(2) g(-1) displayed a reasonably high hydrogen uptake at 77 K with a maximum hydrogen sorption of 3.6 wt% at 2.5 MPa. These results suggest that CA are promising candidate hydrogen storage materials.

Fine grained Ba(1-x)Sr(x)TiO3 ceramics by spark plasma sintering.

Fine grained Ba(0.75)Sr(0.25)TiO3 (BST) ceramics were prepared via spark plasma sintering technique. BST nano-powders freshly prepared by a low-temperature direct solution synthesis technique were used as starting materials. X-ray diffraction measurements indicated that the ceramics had a pure perovskite phase and the observation under scanning electron microscope revealed that the ceramic had a grain size in the range of 50 to 300 nm. The dielectric properties of the fine-grained BST ceramics were determined at different temperatures and frequencies. At room temperature, the ceramics exhibited a moderate dielectric constant (3962 +/- 10), a good dielectric tunability (53.84% under a dc bias of 19.72 kV/cm). The highest tunability and figure of merit (FOM) values are 83.27% at 50.2 degrees C and 289.28 at 62.3 degrees C, respectively. These results suggested that the BST ceramics are suitable for use in tunable microwave devices.

Diagnostic x-ray dosimetry using Monte Carlo simulation.

An Electron Gamma Shower version 4 (EGS4) based user code was developed to simulate the absorbed dose in humans during routine diagnostic radiological procedures. Measurements of absorbed dose using thermoluminescent dosimeters (TLDs) were compared directly with EGS4 simulations of absorbed dose in homogeneous, heterogeneous and anthropomorphic phantoms. Realistic voxel-based models characterizing the geometry of the phantoms were used as input to the EGS4 code. The voxel geometry of the anthropomorphic Rando phantom was derived from a CT scan of Rando. The 100 kVp diagnostic energy x-ray spectra of the apparatus used to irradiate the phantoms were measured, and provided as input to the EGS4 code. The TLDs were placed at evenly spaced points symmetrically about the central beam axis, which was perpendicular to the cathode-anode x-ray axis at a number of depths. The TLD measurements in the homogeneous and heterogenous phantoms were on average within 7% of the values calculated by EGS4. Estimates of effective dose with errors less than 10% required fewer numbers of photon histories (1 x 10(7)) than required for the calculation of dose profiles (1 x 10(9)). The EGS4 code was able to satisfactorily predict and thereby provide an instrument for reducing patient and staff effective dose imparted during radiological investigations.

A use study of speech pathology and audiology periodicals at Illinois State University.

No core list of periodicals exists for speech pathology and audiology. Faced with the prospect of having to cancer periodicals for all subjects, the science librarians at Illinois State University decided to determine which science periodicals were used most heavily. A one-year study of science periodical reshelving and interlibrary loan requests yielded ranked lists of periodicals important to speech pathology and audiology faculty and students at Illinois State University. The three most heavily used journals were the Journal of Speech and Hearing Research, ASHA, and Topics in Language Disorders. Most of the periodicals on the lists were indexed by either MEDLINE or UnCover, or by both. While the lists of journals developed in the study are not sufficient to serve as true core lists, they should be useful to libraries supporting comparable programs in speech pathology and audiology.

Aspirin, salicylate, sulfite and tartrazine induced bronchoconstriction. Safe doses and case definition in epidemiological studies.

Allergic-like reactions to chemical components of foods and medicines may be common. The prevalence of idiosyncratic reactions to aspirin, salicylate, metabisulfite and tartrazine is not known. We used a tertiary referral clinic population to estimate safe exposure doses for epidemiological studies. A 15% decrease in the amount of air expired in one second was defined a positive response. The median effective molar doses of the agents were remarkably similar: metabisulfite 0.19 mM, 34.4 mg [95% confidence interval (CI) 0.14, 0.27 mM]; tartrazine 0.10 M, 55.0 mg (95% CI 0.05, 0.21 mM); aspirin 0.09 mM, 16.5 mg (95% CI 0.04, 0.19 mM); and salicylate 0.11 mM, 15.3 mg (95% CI 0.05, 0.27 mM). Doses to which the most sensitive (5%) and practically all (95%) susceptible persons might respectively respond are: metabisulfite 4.6 mg, 255.8 mg; tartrazine 3.4 mg, 885.6 mg; aspirin 0.8 mg, 332.3 mg; and salicylate 2.6 mg, 89.9 mg. Doses within these ranges can be used in epidemiological studies.

Aspartame is no more likely than placebo to cause urticaria/angioedema: results of a multicenter, randomized, double-blind, placebo-controlled, crossover study.

BACKGROUND: Anecdotes and single case reports have suggested that the high-intensity sweetener, aspartame, may be associated with allergic/hypersensitivity-type reactions. METHODS: We conducted a multicenter, placebo-controlled clinical study to evaluate individuals who had experienced urticaria and/or angioedema allegedly associated with ingestion of an aspartame-containing product. Despite extensive recruiting efforts over 4 years, only 21 subjects could be enrolled. After admission to clinical research units, subjects were given aspartame and placebo in a randomized, double-blind, crossover fashion. Subjects received, on different days, increasing doses (50, 300, 600 mg) of aspartame and placebo at 8:00 AM, 10:00 AM, and noon. Subjects who weighed less than 40 kg received one half of these doses. Conversion products of aspartame, aspartyl-phenylalanine diketopiperazine and beta-aspartame, were also included in the aspartame arm of the study. Positive reactions were defined as urticaria (hives with wheals 4 mm or more in diameter with a collective diameter of at least 15 mm or one or more hives with a wheal of 4 mm or greater with a flare of 8 mm or greater) or as angioedema. RESULTS: According to these criteria, four reactions were observed; two followed aspartame ingestion and two followed placebo ingestion (p = 1.00). The incidence of other adverse experiences was no different after aspartame versus placebo ingestion (p = 0.289). CONCLUSION: These results indicate that aspartame and its conversion products are no more likely than placebo to cause urticaria and/or angioedema reactions in subjects with a history consistent with hypersensitivity to aspartame.

Quantification of pollen solute release using pollen grain column chromatography.

The impact of pollen on the respiratory mucosa was modeled by studying the process by which solutes are eluted from pollen grains. Rye grass (Lolium perenne), short ragweed (Ambrosia artemisiifolia), and white oak (Quercus alba) pollens were packed between glass wool plugs in small columns. Water was pumped through the columns and the eluate solute yield was determined by measurement of the dry solute weight. Solute separation was rapid, and concentrations and osmolalities of the eluate decreased exponentially. Theoretical initial solute concentrations were 179 g/l for rye grass, 55 g/l for short ragweed and 349 g/l for oak pollen eluates. Theoretical initial osmolarities of the same eluates were 321 mOsm/kg for rye grass, 196 mOsm/kg for ragweed and 424 mOsm/kg for oak pollen. Sequential separation of allergens (Lol p I, Amb a I, Amb a V), enzymes and proteins was demonstrated by specific assays. These observations suggest that the complex stimulus produced immediately after pollen grain hydration at the respiratory mucosal fluid interface is much more intense than previously envisioned. Sequential separation of pollen components has important implications for the production of improved allergenic extracts.

Quantitative studies of cutaneous hypersensitivity: the prevalence of epicutaneous flare reactions to allergenic pollen extracts.

The flare reactions produced by epicutaneous tests with 68 undiluted allergenic pollen extracts were measured in 550 allergic patients. Skin test reactions greater than or equal to 2, greater than or equal to 5, greater than or equal to 10, greater than or equal to 20, and greater than or equal to 30 mm in diameter, respectively, were detected in approximately 67%, 22%, 10%, 3%, and 1% of the 34,700 skin tests. With the Kolmogorov-Smirnov difference test, the cumulative frequency of reaction diameters and loge-transformed diameters of all reactions and reactions to individual allergenic extracts differed significantly (p less than or equal to 0.01) from a normal distribution. The ability to identify specific differences between reactions to closely related pollen extracts was evaluated. Specific reactions could be reliably identified with greater than or equal to 10 mm diameter flares. This arbitrary conservative threshold was used to estimate the relative prevalence of positive reactions to each allergenic extract. Seven allergenic extracts elicited the first quartile of all positive reactions. Thirteen, 18, and 30 allergenic extracts, respectively, were needed to elicit the second, third, and fourth quartiles of all positive reactions. Reactions to amphiphilous, as well as anemophilous, pollens were detected. Skin test reactions to grasses were more prevalent than reactions to weeds and trees. The most informative allergenic extracts for the detection of patients who exhibited a positive reaction to any extract were from red fescue-grass pollens, mesquite, short ragweed, red clover, and timothy-grass pollens.

Pollen grain column chromatography: quantitation and biochemical analysis of ragweed-pollen solutes.

The kinetics, quantitative yield, and sequence of solute release during the extraction of allergenic substances from short ragweed (Ambrosia artemisiifolia) pollen were compared with a conventional batch-type method and the novel technique of pollen grain column chromatography. With the batch method, 14.6 +/- 1.7 mg of pollen solutes were eluted per 100 mg of dried defatted pollen in 1 minute; the 24-hour solute yield was 27.4 +/- 2.7 mg. With the column method, 3.7 +/- 1.3 mg of pollen solutes were eluted in 1 minute; the 24-hour solute yield was 29.3 +/- 2.1 mg. The kinetics of solute release with the column method were modeled as the simultaneous first-order elution of ragweed-pollen solutes into three hypothetical compartments. The theoretical initial solute concentration was 50 gm/L. The isoelectric focusing patterns, optical properties, distributions of enzymes, Ra5, and antigen E activities were consistent with the sequential separation of ragweed-pollen solutes and the three compartment model. Enzyme activities were eluted either maximally in the first minute (phosphatases and N-acetyl-beta-glucaminidase) or delayed until 10 minutes (leucine aminopeptidase). Ra5 was eluted rapidly, whereas antigen E was eluted during a more prolonged period. Pollen grain chromatography provides a simple, reproducible method for studying pollen solute release.

Double-blind comparison of terfenadine, chlorpheniramine, and placebo in the treatment of chronic idiopathic urticaria.

The efficacy of terfenadine, a nonsedating H1 antihistamine, in the management of chronic idiopathic urticaria was compared with chlorpheniramine and placebo in a parallel multicenter trial. Subjects with symptoms of hives for 3 days per week for at least 6 weeks were initially screened and admitted if no identifiable cause for symptoms could be determined. Patients entered a single-blind placebo period, and if hives of moderate severity were present for at least 3 days during the week, they were randomly assigned in a double-blind fashion to take terfenadine, 60 mg twice daily, chlorpheniramine, 4 mg three times a day, or placebo for 6 weeks. Data were analyzed for 122 patients. Those patients receiving both active treatments noted significant improvement in symptoms: pruritus, redness, number of hives, and waking hours during which hives were present, at the end of the first day of therapy. Symptom control by terfenadine was statistically superior to placebo during all 6 weeks, as rated by both patients and investigators. However, statistical significance was not achieved for chlorpheniramine at all observation points. Diphenhydramine was permitted as a relief medication for refractory symptoms and was taken by 52% of subjects receiving placebo, 26% taking chlorpheniramine, and only 9% of patients who were receiving terfenadine. In addition to providing superior symptom control, terfenadine caused less drowsiness and fatigue than chlorpheniramine. Terfenadine is a useful therapeutic agent for primary management of chronic idiopathic urticaria.

Terfenadine treatment of fall hay fever.

A double-blind, parallel, multicenter study was undertaken in 215 ragweed skin test positive-patients with fall hay fever. The patients were randomized and treated for seven days with either 60 mg terfenadine twice daily, morning and evening, and a placebo at noon, or with 4 mg chlorpheniramine or placebo three times daily. The severity of nasopharyngeal itching, sneezing, rhinorrhea, nasal congestion, and itchy, watery, red eyes was ranked daily by patients and evaluated before and after treatment by the physician investigators. The patients reported a significant reduction in symptoms within one day. The physician investigators detected moderate to complete relief of symptoms in a greater proportion of the patients treated with terfenadine (70%) and chlorpheniramine (73%) than in the placebo-treated patients (48%). The incidence of sedation with terfenadine treatment (2.5%) was not different from that with placebo (2.4%) and both were lower than with chlorpheniramine (7.6%). We conclude that terfenadine is as effective as chlorpheniramine for the treatment of fall hay fever and that, unlike chlorpheniramine, the incidence of sedation with terfenadine was not different from placebo.

A novel Candida albicans skin test antigen: efficacy and safety in man.

Yeast phase Candida albicans (ATCC No. 10231) was grown in a nonantigenic medium, harvested and lyophilized. Ammonium sulfate fractions of an aqueous extract of the lyophilized cells were evaluated and the fraction yielding the highest specific delayed cutaneous reactivity in sensitized guinea-pigs was used to prepare a C. albicans skin test antigen (CASTA). The safety of the antigen was evaluated by measuring immediate and delayed (0.25, 6, 24, 48 and 72 h) cutaneous reactions in atopic and nonatopic human subjects. The outcome of three repetitive monthly Mantoux skin tests with 0.01-1 microgram antigen doses was used to test for booster effects in 14 subjects and to estimate a safe initial test antigen dose. The utility of a single skin test as a measure of cell-mediated immunity was evaluated in 40 healthy subjects. Reactor rates (greater than or equal to 2 mm, 48 h) of 40% and 85% were detected, respectively, with doses of 0.0316 and 1 microgram. Using a skin test reaction diameter greater than or equal to 5 mm at 48 h, the reactor rate was 50% for the 1-microgram dose. The only adverse reaction (45 mm, 0.25 h) was detected with the 1-microgram dose in an atopic subject who also exhibited exquisite scratch test reaginic hypersensitivity to C. albicans allergen. The prevalence of other adverse reactions to this antigen compared favorably with that to other antigens used for recall antigen testing. These studies suggest the 1-microgram CASTA dose can be used for effective, safe recall antigen skin tests.

Aspartame and susceptibility to headache.

We performed a double-blind crossover trial of challenges with 30 mg of aspartame per kilogram of body weight or placebo in 40 subjects who reported having headaches repeatedly after consuming products containing aspartame. The incidence rate of headache after aspartame (35 percent) was not significantly different from that after placebo (45 percent) (P less than 0.50). No serious reactions were observed, and the incidence of symptoms other than headache following aspartame was also equivalent to that after placebo. No treatment-related effects were detected in vital signs, blood pressure, or plasma concentrations of cortisol, insulin, glucagon, histamine, epinephrine, or norepinephrine. Most of the subjects were well educated and overweight and had a family or personal history of allergic reactions. The subjects who had headaches had lower plasma concentrations of norepinephrine (P less than 0.0002) and epinephrine (P less than 0.02) just before the development of headache. We conclude that in this population, aspartame is no more likely to produce headache than placebo.

The prognostic significance of recall antigen testing in melanoma patients.

A quantitative assessment of the long-term prognostic value and clinical usefulness of recall antigen reactions in patients with malignant melanoma is not available. The authors evaluated longitudinal observations of survival made in 846 patients over a 12-year period. Each patient was initially studied with Mantoux-type recall antigen skin tests. The patients were categorized with respect to the following: high (greater than 5 mm) or low (less than or equal to 5 mm) averaged skin test reaction diameters at 48 hr; Clark level; tumor stage (I = localized tumor, II = local extension and/or region lymph node metastasis, III = systemic metastasis); ulceration; site of primary; histologic type; age; and sex. The percentage of high reactors in Stages I, II, and III were 44.3%, 37.4%, and 25%, respectively. Survival was evaluated with the Cox-Mantell hazard function model and the Cox regression model. The significant (chi-squared; probability) risk factors detected were tumor stage (94.58; less than or equal to 0.0001), Clark level (19.37; less than or equal to 0.0001), sex (16.97; less than or equal to 0.0001), and skin test reactivity (7.48; less than or equal to 0.0062). A significant relationship also was detected between skin test reactor status and the tumor stage (p less than or equal to 0.0330). When evaluated within each stage of disease, skin test reactivity predicted survival only in Stage II patients (p less than or equal to 0.0080). Five-year survival estimates among Stage II patients were 58% among high reactors and 38% among low reactors.(ABSTRACT TRUNCATED AT 250 WORDS)

Population differences in cutaneous methacholine reactivity and circulating IgE concentrations.

We evaluated the incidence of allergic and vasomotor symptoms, serum IgE concentrations, and the cutaneous responses to allergens and/or methacholine in 229 Waorani Indians residing at 300 m altitude near the headwaters of the Amazon River, 39 Tibetans residing at 4000 m in the Himalayas, and 84 healthy subjects residing at 150 m in the piedmont region of North Carolina. The Waorani Indians had a high level of intestinal parasitism, an intermediate level of parasitism occurs in Tibetans, and parasitism is rare in the control population. One Waorani Indian (less than 1%), six Tibetans (15%), and 59 North Carolina subjects (88%) had a past history of allergic or vasomotor symptoms. The prevalence of positive epicutaneous allergen skin tests among the Waorani was 40 in 2910 tests and was significantly less (chi-squared = 184.5; p less than or equal to 0.0001) than the 151 in 1344 incidence in the North Carolina subjects. Large highly significant differences (p less than or equal to 0.0001) were detected between the geometric mean IgE concentrations (international unit per milliliter) and methacholine-induced cutaneous flare responsiveness (millimeter) elicited, respectively, in comparisons between the Waorani Indians (9806 IU/ml; less than 1.0 mm), Tibetans (2930 IU/ml; 2.06 mm), and North Carolina subjects (108 IU/ml; 4.49 mm). Differences in methacholine sensitivity were small and not significant. A highly significant inverse relationship (r = -0.50, p less than or equal to 0.0001) was detected between the circulating IgE concentrations and the methacholine-induced cutaneous flare responsiveness in this cross-cultural, cross-environmental comparison of three populations.(ABSTRACT TRUNCATED AT 250 WORDS)