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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
351

Investigation on the Adsorption of Mercury Chloride by Powdered Activated Carbon¡GOperation Parameters and Adsorption Isotherm

Liu, Ming-Han 14 September 2001 (has links)
The objective of this study was to investigate the removal of mercury chloride in flue gas emitted from municipal waste incinerator (MWI) by the adsorption of powdered activated carbon derived from the pyrolysis of waste tires (PAC-T). This study focused on the removal efficiency of mercury chloride and the adsorption capacity of PAC-T. The operation parameters investigated included temperature (30¢J and 150¢J) and powdered activated carbon injection rate (0.1, 0.2 and 0.3 g/hr). Experimental tests were conducted by the following three steps¡G the adsorption column test, the adsorption isotherm simulation, and the removal efficiency test in a pilot plant. The adsorption capacity of PAC-T for various inlet mercury chloride concentrations (55~215£gg/m3) at room temperature (30¢J) were 811~2,188£gg-HgCl2/g-PAC, while the absorption capacity of PAC-T at 150¢J were 214~700£gg-HgCl2/g-PAC which were lower than those at room temperature. It suggested that the adsorption capacity of PAC-T decreased as adsorption temperature increased. Furthermore, the adsorption of mercury chloride by PAC-T was an unfavorable adsorption isotherm. The adsorption column tests were performed to assess the rate of mercury chloride uptake by PAC-T at 30 and 150¢J. Results from the adsorption isotherm simulation indicated that mercury chloride at room temperature (30¢J) can be simulated by the Redlich and Peterson isotherm. However, the adsorption of mercury chloride at 150¢J can be simulated by the Langmuir isotherm. Experimental results from the pilot tests indicated that the removal efficiency of mercury chloride increased gradually with retention time and then leveled off as retention time was higher than thirty minutes. Moreover, the removal efficiency of mercury chloride increased dramatically as PAC-T injection rate increased from 0.1 to 0.3 g/hr. The highest removal efficiency of mercury chloride which can be achieved by waste-tire derived powdered activated carbon (PAC-T) and commercial powdered activated carbon (PAC-C) were 86.5% and 98.9%, respectively. In general, PAC-T was comparative to PAC-C for the removal of mercury chloride from flue gas on the basis of both physical and chemical properties and removal efficiency of mercury chloride.
352

Studies of Elastic Properties of Poly(ethylene Glycol)/Lithium Chloride by Brillouin Light Scattering

Chen, Hong-Chang 10 July 2002 (has links)
Abstract The polymer electrolytes (ion conducting polymers) consist of macromolecules (usually in the form of polyethereal units) that are doped with alkali mental salts. The polymer electrolytes are being used in Li-polymer buttery. It is suggested that conductivity in these systems takes place through two distinct events. The first is associated with the charge migration of ions between coordination sites in the host material, and the second is that the conductivity is generally observed to rise with increasing flexibility of the polymer chains. Rayleigh-Brillouin scattering spectra of molecular liquids will provide mechanical relaxation information in the frequency range from 10^8 to 10^11 Hz. We have carried out the Brillouin scattering study of PEG400/LiCl mixtures to probe its elastic properties. The change in the flexibility of polymer chains at different temperatures, the fraction of free ion, and their interactions with polymer all effect the Brillouin spectrum and the present work suggests the usefulness of this technique as an useful tool to probe the various interactions in polymer electrolytes.
353

The aqueous zinc chloride system and its complex formation with cellulose-related compounds

Richards, Norman J., January 1969 (has links) (PDF)
Thesis (Ph. D.)--Institute of Paper Chemistry, 1969. / Includes bibliographical references (p. 49-51).
354

A study of the reactions in the zinc chloride-benzaldehyde-glucose system

Dorcheus, Samuel H., January 1962 (has links) (PDF)
Thesis (Ph. D.)--Institute of Paper Chemistry, 1962. / Includes bibliographical references (p. 44).
355

Synthesis and improvement of high performance PVC and PVDF ultrafiltration membranes

Chen, Chen 08 June 2015 (has links)
The applications of membrane technologies have dramatically increased during the last few decades due to technology improvement and cost reduction. Membrane applications can be found in water and wastewater treatment, pharmaceutical industry, chemical processing industry, food industry, etc. However, the membrane technology faces two major challenges: membrane fouling and membrane lifetime. During the membrane filtration process, membrane fouling caused by natural organic matter (NOM) is an inevitable phenomenon, and physical cleaning or chemical cleaning are required for recovering the performance of membrane. As a result of these cleaning processes, membrane lifetime is shortened. For this reason, it is necessary to improve membrane's fouling resistance and lifetime in order to apply membrane technology in large-scale facilities. This dissertation focuses on improving the fouling resistance and flux performance of polyvinyl chloride (PVC) membrane and polyvinylidene fluoride (PVDF) membrane. Specifically, it is comprised of four parts. First, I prepared PVC membranes by adding different amounts of amphiphilic copolymer (Pluronic F 127) into PVC casting solutions. I optimized the performance of PVC membranes by changing the amount of Pluronic F127 used in the casting solution. The results show that with the increase of Pluronic F 127 content, the pore size and pore density both decrease. Moreover, the membrane surface becomes more hydrophilic as indicated by lower contact angles. In addition, the PVC membrane exhibits remarkable antifouling characteristics after adding Pluronic F 127. Second, I synthesized PVDF membranes by adding PVDF graft poly(ethylene glycol) methyl ether methacrylate (PEGMA) (PVDF-g-PEGMA) as additive in casting solutions via the phase inversion method. The synthesized PVDF membranes have unique pillar-like structures on surfaces, which gives the PVDF membrane a defect-free feature and allows it to generate high flux under low pressure. Third, I investigated the forming mechanism of the pillar-like structure from aspects of solvent and additive. Finally, I investigated the influence of PEGMA dose on the performance of PVDF membranes. I changed the amount of PEGMA used in the casting solution and compared the performance of the synthesized PVDF membranes. To summarize, this dissertation has deepened our understanding of how to improve the fouling resistance and flux performance of PVC membranes and PVDF membranes by using amphiphilic copolymer. In addition, the PVDF membrane I synthesized has unique pillar-like structures that give it defect-free and high flux properties. Overall, the results of this study provide valuable information for PVC and PVDF membrane synthesis for large-scale production.
356

Mechanisms involved in the release of ATP from skeletal myoblasts at low pH

Lu, Lin, 鹿琳 January 2012 (has links)
Lactic acid, which induces pH depression, leads to ATP efflux from muscle to extracellular space: it was reported that CFTR was involved in this process. However, the mechanism by which lactic acid activated CFTR and brought about the ATP release is still unknown. This study was performed to investigate (1) what channels may be involved or even conduct ATP release, and (2) how lactic acid activated CFTR. Expression of the possible channels that may conduct ATP release in L6 cells was investigated using RT-PCR: ClC-2, ClC-3, ClC-7, CACC, VDAC, connexin 40, connexin 43 and pannexin 3 were expressed in L6. Incubation of cultured L6 cells with lactic acid (10 mM) increased the extracellular ATP from 0.6 ± 0.06 to 1.1 ± 0.09 nM (P ? 0.05), indicating that lactic acid stimulated ATP efflux in vitro. The non-specific chloride channel inhibitor, DIDS, failed to abolish the lactic-acid-induced ATP release, suggesting that DIDS-sensitive chloride channels were not involved in the ATP efflux. Among the non-specific inhibitors of connexin channels, gadolinium inhibited acidosis-induced ATP efflux, but carbenoxolone failed to inhibit it, and so the role of connexins remains uncertain. The specific inhibitor of CFTR, CFTRinh-172, and the non-specific open-channel blocker of CFTR, glibenclamide, both abolished the acidosis-induced ATP release, but another specific inhibitor of CFTR, GlyH-101, which blocks CFTR from the external side, failed to abolish the ATP release, suggesting that acidosis-induced ATP is dependent on CFTR-activation, but does not involve ATP moving through the CFTR chloride channel. We hypothesize that, at low pH, the Na+/H+ exchanger (NHX) extruded H+ out of the cell and the resulting intracellular Na+ was transported out by Ca2+/Na+ exchanger (NCX); the localized increase in Ca2+ activated adenyl cyclase (AC), thus elevating intracellular cAMP; cAMP-activated-PKA then phosphorylated CFTR, which regulated an ATP release channel. KT-5720, an inhibitor of PKA, abolished the acidosis-induced ATP release, and forskolin, an agent that elevates cAMP, stimulated it, suggesting that the cAMP/PKA pathway was involved. The specific inhibitor of NCX, SN-6 and KB-R7943, both abolished the acidosis-induced ATP release, supporting a role for NCX in mediating this process. However, amiloride, the non-specific inhibitor of NHX failed to abolish ATP efflux. The whole cell Cl- currents were studied in L6 cells: lactic acid increased the whole cell currents from 2.33 ± 0.10 to 3.54 ± 0.34 nA (P ? 0.05), and this lactic-acid-induced increase in Cl- current could be inhibited by CFTRinh-172, suggesting that the CFTR Cl- channel was opened at low pH. Moreover, forskolin increased whole cell Cl- currents, which supported a role for the cAMP/PKA pathway in the lactic-acid-induced increase in CFTR current. These data confirm that CFTR is involved in the lactic-acid-induced ATP release from L6 cells. The roles of the NCX and cAMP/PKA pathway in activating CFTR at low pH are supported, but further studies are required to determine whether the NHX is involved in CFTR activation and whether connexins participate in ATP release. / published_or_final_version / Physiology / Master / Master of Philosophy
357

Cystic fibrosis transmembrane conductance regulator is involved in therelease of ATP from contracting skeletal muscle

Cai, Weisong., 蔡蔚松. January 2012 (has links)
Contracting skeletal muscle releases ATP into the interstitial space where it is subsequently broken down to adenosine by the action of ecto-5’-nucleotidase. Both ATP and adenosine are vasodilators that contribute to the exercise hyperaemia. However, the mechanism for the release of ATP from muscle during exercise remains unknown. Cystic fibrosis transmembrane conductance regulator (CFTR) is involved in ATP release from muscle at low intracellular pH: this study was performed to investigate whether CFTR was involved in the ATP release from skeletal muscle during contractions. Experiments were performed in rats anaesthetised with sodium pentobarbitone and breathing spontaneously. A microdialysis probe was placed in one gastrocnemius muscle: ATP was determined in interstitial microdialysate samples using a bioluminescence assay. The sciatic nerve was stimulated to induce two bouts of muscle contractions, separated by a recovery period of 40 mins; one of the inhibitors was administered prior to the second bout of contractions. Muscle contractions elevated the interstitial ATP by 1500 to 3000%. In the control experiments, no drug was given: both the contractile force and the increase in interstitial ATP were reproducible in repeated contraction bouts. Infusion of a specific inhibitor of CFTR, CFTRinh-172, did not alter the contractile force, but significantly lowered the interstitial ATP during muscle contractions, suggesting that CFTR was involved in the contraction-induced ATP release. Similarly, infusion of the Protein Kinase A inhibitor, KT5720, significantly reduced interstitial ATP during muscle contractions without altering contractile force, suggesting that CFTR in skeletal muscle is activated through the cAMP/PKA pathway. The increase in interstitial ATP during muscle contraction was also inhibited by the Na/H exchanger inhibitor, amiloride, or the Na/Ca exchanger inhibitor, SN6. It has been also shown that two gap junction hemichannel inhibitors, gadolinium and carbenoxolone, could attenuate the increase of ATP during muscle contraction. These data suggest that CFTR, activated through the cAMP/protein kinase A pathway, is involved in the ATP release during muscle contraction, and that activation of the Na/H exchanger and Na/Ca exchanger was also required, indicating that the signal transduction mechanism for CFTR activation during muscle contractions may be similar to that which is reported to occur at low pH. The preliminary data showed that the gap junction hemichannels might mediate the ATP release from skeletal muscle cells during muscle contraction. / published_or_final_version / Physiology / Master / Master of Philosophy
358

The Role of Chloride Channels in Remote Ischemic Preconditioning of Ventricular Cardiomyocytes

Harvey, Kordan 04 December 2012 (has links)
Sarcolemmal chloride channels and associated cell volume regulatory pathways have been shown to be important in local ischemic preconditioning (IPC) induced protection against myocardial ischemia/reperfusion injury. Similarities between intracellular pathways in remote (rIPC) and classic IPC suggest that these mechanisms may also play an important role in rIPC. rIPC protected cultured rabbit ventricular cardiomyocytes against necrosis caused by 75 minutes simulated ischemia followed by 60 minutes simulated reperfusion. The protective effect was abolished by chloride channel blockade using 50 μM indanyloxyacetic acid 94 (IAA-94). rIPC also reduced peak cardiomyocyte swelling during exposure to 200 mOsm hypo-osmotic buffer. The reduction in peak swelling was also abolished by IAA-94. These results suggest that the protective effect of rIPC is achieved, at least in part, by enhancing cell volume regulation and that this effect is dependent on the availability of chloride channels in a similar fashion to local IPC.
359

The Role of Chloride Channels in Remote Ischemic Preconditioning of Ventricular Cardiomyocytes

Harvey, Kordan 04 December 2012 (has links)
Sarcolemmal chloride channels and associated cell volume regulatory pathways have been shown to be important in local ischemic preconditioning (IPC) induced protection against myocardial ischemia/reperfusion injury. Similarities between intracellular pathways in remote (rIPC) and classic IPC suggest that these mechanisms may also play an important role in rIPC. rIPC protected cultured rabbit ventricular cardiomyocytes against necrosis caused by 75 minutes simulated ischemia followed by 60 minutes simulated reperfusion. The protective effect was abolished by chloride channel blockade using 50 μM indanyloxyacetic acid 94 (IAA-94). rIPC also reduced peak cardiomyocyte swelling during exposure to 200 mOsm hypo-osmotic buffer. The reduction in peak swelling was also abolished by IAA-94. These results suggest that the protective effect of rIPC is achieved, at least in part, by enhancing cell volume regulation and that this effect is dependent on the availability of chloride channels in a similar fashion to local IPC.
360

Effect of combined sodium arsenite and cadmium chloride treatment on heat shock protein gene expression in Xenopus laevis A6 kidney epithelial cells

Khamis, Imran 03 September 2013 (has links)
Sodium arsenite and cadmium chloride are two widespread environmental toxicants which have deleterious effects on living organisms. At the cellular level, sodium arsenite and cadmium chloride cause oxidative stress, dysregulation of gene expression, apoptosis, and the unfolding of protein. Furthermore, both chemical stressors individually have the ability to induce heat shock protein (HSP) accumulation. HSPs are molecular chaperones that aid in protein folding, translocation and in preventing stress-induced protein aggregation. Previously, our laboratory demonstrated that treatment of A6 kidney epithelial cells of the frog Xenopus laevis, with either cadmium chloride or sodium arsenite plus a concurrent mild heat shock resulted in an enhanced accumulation of HSPs that was greater than found with the sum of the individual stressors. To the best of our knowledge, no information is available to date on the effect that these two chemical stressors have in combination on HSP accumulation in aquatic organisms. The present study examined the effect of simultaneous sodium arsenite and cadmium chloride treatment on the pattern of HSP30 and HSP70 accumulation in Xenopus A6 cells. Immunoblot analysis revealed that the relative levels of HSP30 and HSP70 accumulation in A6 cells treated concurrently with sodium arsenite and cadmium chloride for 12 h were significantly higher than the sum of HSP30 or HSP70 accumulation from cells subjected to the treatments individually. For instance, the combined 10 µM sodium arsenite plus 100 µM cadmium chloride treatment resulted in a 3.5 fold increase in HSP30 accumulation and a 2.5 fold increase in HSP70 accumulation compared to the sum of the stressors individually. This finding suggested a synergistic action between the two stressors. Pretreatment of cells with KNK437, an HSF1 inhibitor, inhibited the combined sodium arsenite- and cadmium chloride-induced accumulation of HSP30 and HSP70 suggesting that this accumulation of HSPs may be regulated, at least in part, at the level of transcription. Immunocytochemical analysis employing the use of laser scanning confocal microscopy (LSCM) revealed that simultaneous treatment of cells with the two stressors induced HSP30 accumulation primarily in the cytoplasm in a punctate pattern with some dysregulation of F-actin structure. Increased ubiquitinated protein accumulation was observed with combined 10 µM sodium arsenite and 10, 50 or 100 µM cadmium chloride treatment compared to individual stressors suggesting an impairment of the ubiquitin-proteasome degradation system. Finally, while incubation of A6 cells with 1 µM sodium arsenite plus 10 µM cadmium chloride did not induce a detectable accumulation of HSPs, the addition of a 30 °C mild heat shock resulted in a strong accumulation of HSP30 and HSP70. This study has demonstrated that concurrent sodium arsenite and cadmium chloride treatment can enhance HSP accumulation. Since HSP accumulation is triggered by proteotoxic stress, these findings are relevant given the fact that aquatic amphibians in their natural habitat may be exposed to multiple chemical stressors simultaneously.

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