We report on the gasification of guaiacol and phenol in supercritical water at 400−700 °C. The reactions were conducted in sealed quartz tubes, at times with added Ni wires that ran the entire length ...of the reactor. These reactors allowed the homogeneous and heterogeneous SCWG rates to be quantified separately for the first time. Guaiacol is mainly gasified into hydrogen, carbon dioxide, carbon monoxide, and methane. The rest of the guaiacol decomposes to phenol and o-cresol or reacts to form char. Nickel does not affect the conversion of guaiacol to phenol and o-cresol, but it significantly changes the gas product compositions. Phenol is mainly gasified into hydrogen, carbon dioxide, and methane. Hydrogen was the most abundant product at high phenol conversions. The gas compositions measured experimentally were largely consistent with those anticipated from chemical equilibrium calculations. In the absence of nickel, phenol conversions up to 68% were reached after 1 h. In the presence of Ni wire, complete conversion was obtained within 10 min. These results show that homogeneous, uncatalyzed gasification in supercritical water is slow, but rates are greatly increased by added Ni. The pseudo-first-order rate constant at 600 °C for homogeneous gasification of phenol is 3.0 (± 0.4) × 10-4 s-1, and the rate constant for Ni-catalyzed gasification is 1.1 (± 0.1) × 10-3 cm/s.
We gasified cellulose in supercritical water, in the absence of heterogeneous catalytic effects, by using quartz reactors. We also report the first systematic study of the effects of temperature, ...cellulose loading, water density, and reaction time on the production of H2, CH4, CO, and CO2 from supercritical water gasification. The results show that the total gas yields and H2 mole fraction are lower in quartz reactors than in stainless steel reactors, suggesting that the gases from previous studies in metal reactors arise from both homogeneous and heterogeneous reactions, even in the absence of an added catalyst. The rate of formation for all gas species increases with temperature. Manipulating cellulose loading and water density provides an efficient means to control the product selectivity, since the relative amounts of H2 and CH4 were strongly influenced by these two process variables.
We examined the gasification of phenol and glycine in supercritical water (SCW). For phenol SCW gasification, the water density and phenol loading were varied to determine their effects. Increasing ...the water density at a constant phenol loading lowered the phenol conversion for Ni-catalyzed reactions. Increasing the phenol loading at a fixed water density increased the conversion. The H2 yields at equilibrium increased with decreasing water density, decreasing phenol loading, and increasing temperature. Glycine was much more resistant to gasification than phenol. Large amounts (20%–90%) of the initial carbon remained in the aqueous phase even after 1 h for both homogeneous and Ni-catalyzed reactions. Solid material was also produced. Of the gases that were formed, CO was most abundant from the homogeneous reactions, while hydrogen was the most abundant in the presence of a nickel catalyst. The Ni catalyst assisted in glycine gasification, as less carbon was found in the aqueous phase, and gas yields were increased.
The American Family Physician (AFP) photo competition encourages students and residents to share their stories through photographs about how they use the AFP journal.
Neff announces the new free mobile app for "AFP By Topic." This app allows users to quickly access the best current information that the American Family Physicians has to offer on the most commonly ...sought topics from virtually anywhere using almost any Web-enabled mobile device. "AFP By Topic: Editors' Choice of Best Current Content" makes the best content from AFP Online for 45 clinical topics available in one place for one's convenience. The editors update these collections continually to ensure that they remain as current and useful as possible. Among other things, he also provides steps on how to navigate this app.
Millions of people are using social media networks, such as Facebook and Twitter, including health professionals and patients who exchange information and insights about topics relevant to family ...medicine. The “U.S. Preventive Services Task Force” (page 408) and “Putting Prevention into Practice” (page 411) departments discuss screening infants for hyperbilirubinemia to prevent chronic bilirubin encephalopathy. ...the four “Tips from Other Journals” (starting on page 426) discuss different approaches to screening for neonatal hyperbilirubinemia.
The American Family Physician (AFP) photo contest encourages students and residents to share their stories through photographs about how they use the AFP journal. Winning photos were selected based ...on creativity, originality, and clarity in demonstrating how they learned from the journal.
In an effort to reach out to the international family- medicine community and other health care professionals in developing countries, the AAFP has arranged to make the journals available through the ...Health InterNetwork Access to Research Initiative (HINARI), a public-private partnership sponsored by the World Health Organization (WHO). Local health sector and medical education institutions that are eligible to have access to the HINARI network include national universities, research institutes, professional schools (medicine, nursing, pharmacy, public health, dentistry), teaching hospitals, government offices, and national medicine libraries.
Neff presents a reprint from the Subcommittee on Management of Acute Otitis Media, which was convened by the American Academy of Pediatrics and the American Academy of Family Physicians, regarding ...the diagnosis and management of acute otitis media (AOM). The paper discusses the released evidence-based clinical practice guideline, which provides a specific definition of AOM, and also addresses pain management, initial observation versus antimicrobial treatment, appropriate choices of antimicrobials, and preventive measures in children between 2 mos and 12 yrs of age.
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