Method for the control of NOx emissions in long-range space travel

The wheat straw, an inedible biomass that can be continuously produced in a space vehicle has been used to produce activated carbon for effective control of NOx emissions from the incineration of wastes. The optimal carbonization temperature of wheat straw was found to be around 600 degrees C when a burnoff of 67% was observed. The BET surface area of the activated carbon produced from the wheat straw reached as high as 300 m2/g. The presence of oxygen in flue gas is essential for effective adsorption of NO by activated carbon. On the contrary, water vapor inhibits the adsorption efficiency of NO. Consequently, water vapor in flue gas should be removed by drying agents before adsorption to ensure high NO adsorption efficiency. All of the NO in the flue gas was removed for more than 2 h by the activated carbons when 10% oxygen was present and the ratio of carbon weight to the flue gas flow rate (W/F) was 30 g min/L, with a contact time of 10.2 s. All of NO was reduced to N2 by the activated carbon at 450 degrees C with a W/F ratio of 15 g min/L and a contact time of 5.1 s. Reduction of the adsorbed NO also regenerated the activated carbon, and the regenerated activated carbon exhibited an improved NO adsorption efficiency. However, the reduction of the adsorbed NO resulted in a loss of carbon which was determined to be about 0.99% of the activated carbon per cycle of regeneration. The sufficiency of the amount of wheat straw in providing the activated carbon based on a six-person crew, such as the mission planned for Mars, has been determined. This novel approach for the control of NOx emissions is sustainable in a closed system such as the case in space travel. It is simple to operate and is functional under microgravity environment.

Decomposition of NO on the alkalized Pt/Al2O3

Catalytic decomposition of NO on platinum catalysts at 873-1,173 K was investigated in the present work. The yield of N2 in the NO decomposition process was significantly increased on the alkalizing Pt/Al2O3 catalyst. The enhancement may be attributed to a trap of additional NO molecules by basic sites ofthe alkalized catalyst. The interstitially adsorbed species (NaOH(NO)Pt) might increase the NO adsorption strength during the catalytic NO reduction process. Pt on the high acidity HY was also active for catalytic decomposition of NO. Nevertheless, its activity decreased at higher temperatures (>1,073 K) because of the distortion of the HY framework. Combined results of XPS (X-ray photoelectron spectra) and TPR (temperature programmed reduction) showed that PtO and PtO2 were the main active species on the alkalized Al2O3 and HY during NO reduction.

Catalytic reduction of NO on copper/MCM-41 studied by in situ EXAFS and XANES

Speciation of copper in the channels of MCM-41 during reduction of NO with CO at 473-773 K was studied by in situ extended X-ray absorption fine structural (EXAFS) and X-ray absorption near edge structural (XANES) spectroscopies in the present work. The component fitted (in situ) XANES spectra of the catalyst showed that about 72% of metallic copper (Cu(0)) in MCM-41 was oxidized to higher oxidation state coppers (Cu(II) (46%) and Cu(I) (26%)) during the NO reduction process (at 473 K). By EXAFS, we also found that in the NO reduction process, oxygen was inserted into the metallic copper matrix and led to a formation of the copper oxide species with a Cu-O bond distance of 1.93 A which was greater than that of the model compound Cu(2)O (typically 1.86 A). At 573-673 K, mainly Cu(II) was found in the channels of MCM-41. Nevertheless, at a higher temperature (e.g., 773 K), about 61% Cu(I), 31% Cu(II), and 8% Cu(O) with averaged Cu-Cu and Cu-O bond distances of 3.04 and 1.88 A, respectively were observed, that might account for the high selectivity-to-decomposition (S/D) ratios for yields of N(2) and CO(2) in the catalytic reduction of NO with CO.

Speciation of copper in the incineration fly ash of a municipal solid waste

The speciation of copper and zinc in the incineration fly ash of a municipal solid waste in Taiwan was investigated in the present work. By the least-squares fitted X-ray absorption near edge structural (XANES) spectroscopy, we found that CuCO3, CuOH2, and CuO (fractions of 0.09, 0.39 and 0.51, respectively) were the main copper species in the fly ash. Quantitative analysis of the extended X-ray absorption fine structural (EXAFS) spectra indicated that the bond distance of Cu-O in the fly ash was 1.96 A with a coordination number (CN) of 3.9 in the first shell of copper. In the second shell, the bond distance and CN of Cu-(O)-Cu were 2.91 A and 2.7, respectively. In addition, speciation of Zn was also examined in the same X-ray absorption energy (8780-9970 eV). The bond distance of Zn-O and Zn-O-Zn were 1.97 and 2.94 A, respectively. However, the Zn-O-Cu structure was not found because of the physically unreasonable sigma(2) (Debye-Waller factor) values in the EXAFS data fitting process.

An engineering assessment of the burning of the combustible fraction of construction and demolition wastes in a redundant brick kiln

This paper confirms both technical feasibility and economic potential via the use of redundant brick kilns as an alternative option for disposal of the combustible fractions of construction and demolition wastes by a three-stage analysis. To assess such an idea, one brick kiln was selected for performing an engineering feasibility study. First of all, field sampling and lab-analyses were carried out to gain a deeper understanding of the physical, chemical, and thermodynamic properties of the combustible fractions of construction and demolition wastes. Kinetic parameters for the oxidation of the combustible fractions of construction and demolition wastes were therefore numerically calculated from the weight loss data obtained through a practice of thermogravimetric analyzer (TGA). Secondly, an engineering assessment for retrofitting the redundant brick kiln was performed based on integrating several new and existing unit operations, consisting of waste storage, shredding, feeding, combustion, flue gas cleaning, and ash removal. Such changes were subject to the operational condition in accordance with the estimated mass and energy balances. Finally, addressing the economic value of energy recovery motivated a renewed interest to convert the combustible fractions of construction and demolition wastes into useful hot water for secondary uses.

Color Doppler sonography for ventral hernias in patients with acute abdomen: preliminary findings

PURPOSE

We assessed the usefulness of color Doppler sonography (CDUS) in evaluating the vascular status of ventral hernias and distinguishing incarcerated from nonincarcerated ventral hernias.

METHODS

In this prospective study, 10 patients who presented with acute abdomen and had ventral hernias underwent CDUS from August 1999 to May 2000. Patient age and sex and the clinical severity, mode of therapy, and outcome in these 10 patients were evaluated in relationship to the CDUS findings.

RESULTS

Five patients had readily visible flow in the bowel within the hernial sac on CDUS. Two of these 5 had spontaneous reduction under conservative treatment, and 3 had asymptomatic ventral hernias with acute abdomen caused by spontaneous bacterial peritonitis. Barely visible flow was visualized in the bowel by CDUS in 4 other patients. Three of these underwent emergency surgery because of peritoneal signs; 2 of them were found to have ischemic changes in the bowel. The fourth patient underwent a successful manual reduction. The remaining patient had absent flow in the bowel on CDUS and underwent emergency surgery, which revealed gangrenous changes in the bowel.

CONCLUSIONS

The intensity of the Doppler signals on CDUS appears to be a promising predictor of bowel viability in cases of ventral hernia. Thus, CDUS should impact the determination of the treatment plan, including whether to provide conservative treatment or surgery.

Emphysematous pyelonephritis in a renal allograft: successful treatment with percutaneous drainage and nephrostomy

Emphysematous pyelonephritis in renal transplant allograft occurs rarely. This is a case report on a 55-year-old man who had renal transplantation in 1983 and developed post-transplant diabetes mellitus in 1984. This patient suffered from fever and right low abdominal pain and was subsequently diagnosed as emphysematous pyelonephritis by computerized tomography. He was successfully treated with percutaneous drainage, percutaneous nephrostomy and parenteral antibiotics. Although the management of emphysematous pyelonephritis has been a subject of controversy, we recommend consideration of renal preservation in patients with few risk factors, especially in those patients presenting with chronic renal insufficiency, solitary kidney and transplant allograft.

Mineralization of CCl4 with copper oxide

Experimentally, CCl4 was effectively mineralized by CuO to yield stable inorganic species of CO2 and CuCl2 (CCl4 + 2CuO --> 2CuCl2 + CO2). High CCl4 conversions (63-83%) were found in the mineralization process performed at 513-603 K for 10-30 min. Using X-ray-absorption near edge structure (XANES) and X-ray photoelectron spectroscopies, we found that most CuCl2 was encapsulated in the CCl4-mineralized product solid (mineralization at 513 K for 30 min). At higher mineralization temperatures (563-603 K), CuCl2 was found to be predominant on the surfaces of the mineralization product. Speciation of copper in the mineralization product solid was also studied by extended X-ray absorption fine structure (EXAFS) spectroscopy. Bond distances of Cu-O and Cu-Cl in the CCl4-mineralized product solid were 1.93-1.94 and 2.10-2.12 , respectively, which were greater than those of normal CuO and CuCl2 by 0.03-0.07 A. The increase of the bond distances for Cu-O and Cu-Cl might be due to Cl insertion and concomitant structural perturbation of unreacted CuO in the mineralization process. Forthe second shell around copper atom, bond distances of Cu-(O)-Cu also increased by 0.03-0.05 A, and the coordination numbers of Cu-O and Cu-(O)-Cu decreased, as expected, in the mineralization process. In addition, stoichiometrically excess oxygen atoms were found on the solid surfaces, and they might play an important role in the mineralization of CCl4, leading to the formation of CO2 and Cl. Chloride atoms might be further captured by CuO, yielding CuCl2 in the mineralization process. This work exemplifies the utilization of X-ray spectroscopies (XANES, EXAFS, and XPS) to reveal the speciation and possible reaction pathway in a very complex mineralization process in detail.

Obstructive jaundice caused by hepatocellular carcinoma: detection by endoscopic sonography

Tumor thrombus in the extrahepatic biliary tree is a rare mechanism of obstructive jaundice. We present a patient with a minute hepatocellular carcinoma in the caudate lobe that invaded the common hepatic duct and caused biliary obstruction. Endoscopic sonography showed a tumor thrombus with central echogenicity and a "nodule-in-nodule" pattern and suggested the correct diagnosis.

Oxidation kinetics of the combustible fraction of construction and demolition wastes

Proper disposal of construction and demolition wastes (CDW) has received wide attention recently due to significantly large quantities of waste streams collected from razed or retrofitted buildings in many metropolitan regions. Burning the combustible fractions of CDW (CCDW) and possibly recovering part of the heat content for economic uses could be valuable for energy conservation. This paper explores the oxidation kinetics of CCDW associated with its ash characterization. Kinetic parameters for the oxidation of CCDW were numerically calculated using thermal gravimetric analysis (TGA) and the resultant rate equations were therefore developed for illustrating the oxidation processes of CCDW simultaneously. Based on three designated heating rates, each of the oxidation processes can be featured distinctively with five different stages according to the rate of weight change at the temperature between 300 K and 923 K. In addition, Fourier transform infrared (FTIR) spectroscopy was employed, associated with a lab-scale fixed-bed incinerator for monitoring the composition of flue gas. Carbon dioxide (CO2) was found as a major component in the flue gas. The fuel analysis also included an ash composition analysis via the use of X-ray powder diffraction (XRD), atomic absorption (AA) spectroscopy, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDX). The ash streams were identified as nonhazardous materials based on the toxicity characteristic leaching procedure (TCLP). Overall, the scientific findings gained in this study will be helpful for supporting a sound engineering design of real-world CCDW incineration systems.

EXAFS and XANES studies of copper in a solidified fly ash

Speciation of copper in the fly ash solidification process has been studied by X-ray based spectroscopies inthe present work. Fourier transformed EXAFS (extended X-ray absorption fine structural) spectra of the solidified fly ashes showed that the bond distance of Cu-O (first shell) was 1.96 A with a coordination number (CN) of about 3.0. However, in the second shell of copper atoms, the bond distance of Cu-(O)-Cu was decreased by 0.12-0.22 A during solidification, which might cause the stabilization of the CuO species in the solidified fly ash matrix. By the least-squares fits of the XANES (X-ray absorption near edge structural) spectra, fractions of the main copper species in the solidified fly ashes such as CuCl2 (0.08-0.11), Cu2O (0.07-0.09), Cu(OH)2 (0.31-0.33), and CuO (0.49-0.52) were observed. Combined EXAFS and XANES observations suggested that chemical reactions such as hydroxylation of CuCl2 and oxidation of Cu2O and/or metallic Cu might involve in the solidification process, which also led to a significant reduction of the leachability of copper from the solidified fly ashes.

Phospholipid hydroperoxide glutathione peroxidase protects against singlet oxygen-induced cell damage of photodynamic therapy

Phospholipid hydroperoxide glutathione peroxidase (PhGPx) is an important enzyme in the removal of lipid hydroperoxides (LOOHs) from cell membranes. Cancer treatments such as photodynamic therapy (PDT) induce lipid peroxidation in cells as a detrimental action. The photosensitizers used produce reactive oxygen species such as singlet oxygen ((1)O(2)). Because singlet oxygen introduces lipid hydroperoxides into cell membranes, we hypothesized that PhGPx would provide protection against the oxidative stress of singlet oxygen and therefore could interfere with cancer treatment. To test this hypothesis, human breast cancer cells (MCF-7) were stably transfected with PhGPx cDNA. Four clones with varying levels of PhGPx activity were isolated. The activities of other cellular antioxidant enzymes were not influenced by the overexpression of PhGPx. Cellular PhGPx activity had a remarkable inverse linear correlation to the removal of lipid hydroperoxides in living cells (r = -0.85), and correlated positively with cell survival after singlet oxygen exposure (r = 0.94). These data demonstrate that PhGPx provides significant protection against singlet oxygen-generated lipid peroxidation via removal of LOOH and suggest that LOOHs are major mediators in this cell injury process. Thus, PhGPx activity could contribute to the resistance of tumor cells to PDT.

EXAFS study of copper in waste incineration fly ashes

Copper species such as CuCO3, Cu(OH)2, CuS and CuO were found in the bag house and EP (electrostatic precipitator) fly ashes of waste incineration processes by X-ray absorption near edge structural (XANES) spectroscopy. A small amount of Cu(I) and metallic Cu was found in the bag house fly ash. The averaged Cu-O bond distance in the fly ashes determined by EXAFS (extended X-ray absorption fine structural) was 1.96 A with coordination numbers of 2.4-3.9. However, the Cu-(O)-Cu (2nd shell) bond distance of the fly ashes in the incineration process was decreased by 0.19-0.21 A if compared to that of the CuO standard. The coordination numbers of the 2nd shell contribution to the bag house fly ash were not very significant.

In-situ EXAFS study of copper in the electrokinetic remediation process

The speciation of copper in the early stage of the electrokinetic remediation (EKR) process has been studied by extended X-ray absorption fine structure (EXAFS) spectroscopy in the present work. By in-situ EXAFS, we found that copper in a contaminated soil possessed a Cu-O bond distance of 1.98 A with a coordination number (CN) of 5.8. In the second shell, the bond distance of Cu-(O)-Cu was 2.87 A with a CN of 6.4. However, possibly due to the fact that incompact copper atoms in the outer shells were distorted by EKR, the Cu-(O)-Cu (2nd shell) bond distance and the CN of copper in the contaminated soil decreased by 0.08 A and 5.4, respectively in the early stage of the EKR process. Interestingly, after prolonging the contact time to about 80 minutes, the 1st-shell copper atoms were also perturbed by EKR. This work is an example of usefulness of the in-situ EXAFS spectroscopy for detailed studies of the speciation of copper in the contaminated soil during EKR process.

Speciation of As in the blackfoot disease endemic area

Speciation of arsenic (As) in well water and contaminated soil in the blackfoot disease endemic area has been studied by extended X-ray absorption fine structural (EXAFS) spectroscopy in the present work. Experimentally, we found that arsenic in the well water possessed an As-O bond distance of 1.72 A with a coordination number (CN) of 4.3. In the blackfoot disease area, arsenic with a high oxidation state (As(V)) was also observed in the contaminated soil. In the early stage (after 90 minutes) of the electrokinetic remediation (EKR) of the contaminated soil, the in-situ EXAFS data indicated that the CN of As-O (1st shell) decreased slightly, that may be due to the perturbation of the incompact As atoms in the outer shells by EKR.

Gray-scale and color Doppler sonographic diagnosis of epiploic appendagitis

Depending on its location, epiploic appendagitis may mimic nearly any acute abdominal condition. We present the case of a patient with left lower quadrant pain. Sonography demonstrated an ovoid, hyperechoic, noncompressible lesion at the point of tenderness but no inflammatory changes in the adjacent colonic wall. Color Doppler sonography showed no flow in the lesion. Based on the sonographic diagnosis of epiploic appendagitis, conservative treatment was given, with complete recovery in 5 days. Awareness of these sonographic findings may aid in the early diagnosis of epiploic appendagitis and avoid unnecessary treatment.