The hitting the carbon material looks of hole of ordered structure relatively has its more apparent physics and chemical characteristic in the traditional powder sample, this research makes hitting the carbon material of hole in order to utilize the law of mask works and making and lying between the qualification of the view structure to it of preface structure. Utilize different carbon precursor containing carbon proportion, for instance: Carbon material of hole in cane sugar, phenol aldehyde tree ester and pitch come to prepare; And to the structure of hole, for instance: The hole shrinks the homogeneity, hole shrinking rate ,etc. the physical and not last comparison at chemical property. First of all, utilizing has no emulsification to get together (not add any to hand in and unite pharmaceutical) Styrene the single /last sulfic acid potassium / water prepare by polystyrene ball in system. The styrene thickness is reduced to adjust the single weight ratio to styrene of initial pharmaceutical and look on as, then the ball size of polystyrene is diminished, controlling all kinds of technology of the spheroid, can already produce the polystyrene ball under the diameter 100 nm. Use 4 second silicic acid / ammonia water / deionized water / ethanol prepare and oxidize the silicon ball two times on the other hand, experiment course make use of adjust ammonia water in not reacting ear count than may be controlled and oxidized the ball size of silicon 2 times relatively. Experiment to can produce by the twoes of the 100 nms diameter because it oxidize by silicon ball, cause accord with endure research to a the above-mentioned spheroid particle by rice grades of material size already all fully. The second part of experiment includes the carbon material of carbon proportion to prepare in order to utilize differently out and hit the carbon material of hole in order for the source, thereafter utilize SEM, X-ray and Ramam After the instrument analyzes, sum up the property difference of every carbon material and characteristic trend. The result of study reveals, in order to include carbons carbon material structure of hole prepared out of the carbon material source the lower in proportion, its diameter of average hole is smaller, the shrinking rate of hole is larger, the hole wall is thinner and slightly broken in shape. Another result reveals, the graphite intensity of the carbon material of hole relates to material source own one's share structure of carbon, contain benzene ring many line molecular structure and reticular formation facilitate, raise carbonization graphite intensity react, and molecule layer distance light; The influence containing benzene and surrounding the structure among them is superior to the reticular formation. In addition, the experimental result has revealed the material grade of hole in the average diameter of carbon material of hole has already reached for 350 nm.

Thesis (M. Med. Sc.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 63-70).

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 163-174).

Introduction Due to its widespread use, toxicity and volatility, exposure to the chemical formaldehyde has important implications for human health. Asthma is a common chronic inflammatory disease with both genetic and environmental factors. The common symptoms of asthma include wheezing, coughing, and shortness of breath. The objective of the present study is to evaluate the association between exposure to formaldehyde and adult asthma through systematic review. Methods A literature search was conducted using PubMed with keywords of formaldehyde, adult asthma, and other relevant terms. The basic exclusion and inclusion criteria in this study are as follows: Original randomized controlled trials (RCTs) and observational studies were eligible, but not editorials, reviews, case-reports and case‐series. Studies that focused on behavioral change or other outcomes unrelated to asthma were excluded. Lastly, articles in which full text was unavailable were excluded. Finally, after 3 selection rounds, 7 studies were included in the present systematic review. Results: These 7 studies included 3 RCTs, 2 case‐control studies and 2 cross‐sectional studies, published from 1986 to 2013. The 3 RCTs examined participants with and without asthma and investigated the acute effects of formaldehyde on respiratory phenotypes; in contrast, the 4 observational studies examined the long‐term effects of low dose formaldehyde exposure on asthma. Only 1 RCT reported a strong association between formaldehyde and adult asthma, with the intervention group developed an immediate bronchial response at a significantly lower dose of mite allergen than that of the control group with air exposure. The other 2 RCTs found no significant deleterious effect on airway allergen responses after exposure to 500 μg/m3 formaldehyde; and the concentration of formaldehyde found in the indoor environment was of minor importance for developing pulmonary symptoms. Two case-control studies reported a positive association between formaldehyde exposure and asthma symptoms, while the results in the cross‐sectional studies suggested no significant association between formaldehyde exposure and adult asthma. Conclusions Among the 3 reviewed RCTs, only 1 reported a significant association between formaldehyde and asthma. In the 4 reviewed case‐control and cross‐sectional studies, 2 suggested that exposure to formaldehyde had significant effects on bronchial responses. However, these studies represented different characteristics, hence, after integration of them, this review suggests that exposure to formaldehyde in relative low concentration may not have strong association with adult asthma. However, further studies are required to A: Try to identify more potential confounders and choose most suitable model in various conditions; B: investigate multiple patterns of formaldehyde exposure and provide different outcome measurements in RCTs. In addition, this report indicates that it is important to increase the population awareness of choosing environmental friendly decoration materials for reducing formaldehyde exposure. / published_or_final_version / Public Health / Master / Master of Public Health

No description available.

No description available.

Doctor of Philosophy (PhD) / This work involves an experimental and kinetic modelling study of the silver catalysed reaction of methanol to formaldehyde. The motivation for this was the desire to investigate the potential for Process Intensification in formaldehyde production. Formaldehyde production from methanol over silver catalyst is a fast, exothermic process where dilution is used to control heat release, and these properties are both indicators of Process Intensification potential. The process is run adiabatically and produces hydrogen (which is currently burnt). Oxygen is consumed during the reaction but is also required to activate the catalyst and is fed in understoichiometric quantities. The central overall reactions in the silver catalysed process for formaldehyde production are oxydehydrogenation CH3OH + ½ O2 -> CH2O + H2O (DH = -159kJ/mol) and dehydrogenation CH3OH <-> CH2O + H2 (DH = 84kJ/mol). When sufficient oxygen is available, formaldehyde can be further oxidised to carbon dioxide CH2O + O2 -> CO2 + H2O (DH = -519kJ/mol). Formaldehyde can decompose to carbon monoxide and hydrogen CH2O <-> CO + H2 (DH = 12.5kJ/mol). Oxidation of methanol and hydrogen also occurs and other minor products of the reaction are methyl formate, methane and formic acid. These overall reactions do not adequately describe the silver catalysed reaction mechanism. In particular, the overall dehydrogenation reaction does not include oxygen as a reactant, but it will not occur over silver that does not have active atomic oxygen species adsorbed on the surface, and these atomic oxygen species are formed from gas phase oxygen. In the absence of a complete mechanism for silver catalysed formaldehyde production, the intensification of the process was investigated using a thermodynamic model (based on the overall oxydehydrogenation and dehydrogenation reactions, not reaction kinetics). It was found that by using heat exchange (rather than heat generated from the exothermic oxydehydrogenation path) and a lower oxygen concentration in the feed stream, hydrogen selectivity could be increased while maintaining the required methanol conversion. Before this iv opportunity could be further investigated, a complete reaction mechanism that would allow the requirement of oxygen for catalyst activation to be included was required. There is agreement in the literature that two active atomic oxygen species react with methanol on silver. These are weakly bound atomic oxygen (Oa) and strongly bound atomic oxygen (Og). The location of Oa is on the surface of the silver, while the location of Og has been described as being in the silver surface (where it substitutes for silver atoms). Both species react with methanol to form formaldehyde. When the concentration of Oa is high enough, Oa will also react with formaldehyde forming carbon dioxide (while Og will not). The literature presents differing views on the extent of involvement of each atomic oxygen species in industrial formaldehyde production. There is also disagreement on the pathways for water and hydrogen formation. An extensive experimental investigation of the partial oxidation of methanol to formaldehyde was carried out using a flow reactor. The effect of temperature (250- 650°C), reactant concentration (7000-40000ppm methanol) and the feed ratio of methanol to oxygen (2.5-5.5) were studied. The extreme case of methanol reaction with Og in the absence of gas phase oxygen was also investigated. To isolate the effect of secondary reactions, the oxidation of formaldehyde, carbon monoxide and hydrogen were investigated, both in the presence and absence of silver catalyst. When methanol was exposed to silver catalyst that had been activated by being covered in Og (with this being the only source of oxygen) the catalytic nature of Og was demonstrated by the high selectivity to formaldehyde and hydrogen that was achieved (with very little carbon dioxide or water production). When gas phase oxygen was fed to the reactor along with methanol, hydrogen selectivity over silver increased up to about 40% as the concentration of reactants was increased. This result is consistent with the general rule of thumb from industrial practice that hydrogen selectivity is about 50%. When formaldehyde and oxygen were exposed to silver in the flow reactor, the only reaction products were carbon v dioxide and water and the combination of high temperature and excess oxygen was required for complete conversion of formaldehyde. A pseudo-microkinetic model (based on a Langmuir-Hinshelwood mechanism) for the partial oxidation of methanol to formaldehyde (over silver) was taken from the literature and investigated. This model predicts formaldehyde production using only Oa (no other active atomic oxygen species are included) but lacks pathways for reactions between Oa and adsorbed hydrogen or hydroxyl (so the only possible fate of adsorbed H atoms is to desorb as H2). The Oa model was combined with literature models for hydrogen desorption and the reactions involving adsorbed hydroxyl (desorption, self reaction, decomposition and reaction with adsorbed hydrogen). Comparison of this Hybrid model with experimental data showed that reactions involving Oa will predict formaldehyde formation and oxidation, but not hydrogen formation (because the rate of hydrogen desorption is too slow compared with the rate of water formation). It is concluded that any detailed model must include the reaction between methanol and Og (producing hydrogen). Although the reaction between two adsorbed OgH species has been suggested as the pathway for hydrogen formation from Og, this is not certain and so all possible reactions involving Og and hydrogen need be investigated and the appropriate pathways added to the Hybrid model. Once a complete microkinetic mechanism for the partial oxidation of methanol to formaldehyde over silver is available it can be used to further investigate the process intensification of this process. In particular, the use of staged addition of oxygen (to keep the catalyst active) combined with heat exchange (to replace the heat normally supplied by the oxydehydrogenation path) with the aim of simultaneously maximizing methanol conversion and selectivity to formaldehyde and hydrogen.

Proefschrift--Leyden. / "Stellingen" ([2] p.) inserted. Bibliography: p. 101-102.

Thesis (M.S.)--Youngstown State University, 2008. / Includes bibliographical references (leaves 49-52). Also available via the World Wide Web in PDF format.

Thesis (Ph. D.)--University of Pennsylvania, 1921.