Search

The optimal route of sightseeing orders for visiting every Macao World Heritage Site at exactly once was calculated with Simulated Annealing and Metropolis Algorithm(SAMA) after considering real required time or traveling distance between pairs of sites by either driving a car, taking a bus, or on foot. We found out that, with the optimal tour path, it took roughly 78 minutes for driving a car, 115 minutes on foot, while 117 minutes for taking a bus. On the other hand, the optimal total distance for driving a car would be 13.918 km while for pedestrians to walk, 7.844 km. These results probably mean that there is large space for the improvement on public transportation in this city. Comparison of computation time demanded between the brute-force enumeration of all possible paths and SAMA was also presented, together with animation of the processes for the algorithm to find out the optimal route. It is expected that computation time is astronomically increasing for the brute-force enumeration with more number of sites, while it only takes SAMA much less order of magnitude in time to calculate the optimal solution for larger number of sites. Several optimal options of routes were also provided in each transportation method. However, it is possible that in some types of transportation there could be only one optimal route having no circular or mirrored duplicates., 17 pages, 4 figures

The majority of the known prognostic factors in dogs with lymphoma have been evaluated before treatment commences or at the time of diagnosis. Prognostic factors evaluated during the initial phase of treatment are less described but may provide important clinical information. In this retrospective study, 82 canine lymphoma patients were categorized according to the weight change between diagnosis and after 5 weeks of chemotherapy. Dogs that gained greater than 5% or lost greater than 5% of initial body weight were categorized as increased- or decreased-weight groups, respectively. Those in which weight changed less than 5% were categorized as the maintained-weight group. The median progression-free survival (PFS) in the increased-weight group, maintained-weight group and decreased-weight group was 226, 256 and 129 days, respectively. The decreased-weight group had significantly shorter PFS than the increased and maintained groups (P = .023, P = .003, respectively). The median survival time (ST) in the increased-weight group, maintained-weight group and decreased-weight group was 320, 339 and 222 days, respectively. There was no significant difference in ST among the three groups (P = .128). In Cox-regression results, weight change group and initial body weight were significant risk factors associated to PFS (P = .007, P = .001, respectively) while only patient's initial body weight was a significant risk factor to ST (P = .013). In conclusion, evaluation of initial body weight and weight changes over time can provide valuable information regarding PFS and ST in dogs with multicentric lymphoma.

Undoped and cesium-doped zinc oxide (ZnO) thin films have been deposited on sapphire substrate (0001) using the sol–gel method. Films were preheated at 300 °C for 10 min and annealed at 600 and 800 °C for 1 h. The grown thin films were confirmed to be of wurtzite structure using X-ray diffraction. Surface morphology of the films was analyzed using scanning electron microscopy. The photoluminescence (PL) spectra of ZnO showed a strong ultraviolet (UV) emission band located at 3.263 eV and a very weak visible emission associated with deep-level defects. Cesium incorporation induced a blue shift of the optical band gap and quenching of the near-band-edge PL for nanocrystalline thin film at room temperatures because of the band-filling effect of free carriers. A shift of about 10–15 cm−1 is observed for the first-order longitudinal-optical (LO) phonon Raman peak of the nanocrystals when compared to the LO phonon peak of bulk ZnO. The UV resonant Raman excitation at RT shows multiphonon LO modes up to fifth order. Copyright © 2010 John Wiley & Sons, Ltd.

This study aims to evaluate the influence of start-up on polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) concentration in the stack flue gas of incinerators and its contributing PCDD/F emission. The PCDD/F emission of the first sample among three consecutive stack flue gas samples of five intermittent incinerators, which sampled at a stable combustion condition after start-up, is 2-3 times higher than the mean of the others. For verifying the PCDD/F characteristics of incinerators during start-up, one continuous MSWI was investigated for two years. The elevated PCDD/F emissions of the MSWI during start-up could reach 96.9 ng I-TEQN m(-3) and still maintained a high PCDD/F emission (40 times higher than the Taiwan emission limit) even 18 h after the injection of activated carbon, indicating the memory effect. Taking the MSWI for example, which consists of four incinerators, the estimated annual PCDD/F emission from normal operational conditions was 0.112 g I-TEQ. However, one start-up procedure can generate approximately 60% of the PCDD/F emissions for one whole year of normal operations. And the PCDD/F emission, which is the result of the start-ups of four incinerators, was at least two times larger than that of a whole year's normal operations, without consideration for the PCDD/F emission contributed by the long lasting memory effect.

The PCDD/Fs in the ambient air associated with concentration and dry deposition flux of four seasons were characterized in rural area. The mean PCDD/F concentrations were 0.342, 0.221, 0.675, 0.741 pg m(-3) and the mean I-TEQ values were 0.027, 0.016, 0.024, 0.063 pg m(-3) in spring, summer, fall and winter, respectively. Ambient air in winter was higher by a factor of 3.4 and 3.9 for PCDD/F concentration and I-TEQ, respectively, than in summer. The study area is located in a Tropical region. Hence, domestic heating is not found in this area and is not responsible for the elevated winter concentration in comparison to other studies. A smooth plate with a sharp leading edge that is pointed into the wind by a wind vane was used for measuring dry deposition flux of PCDD/Fs. Atmospheric dry deposition fluxes of total PCDD/Fs were 140, 116, 137, and 207 pg m(-2)day(-1) in spring, summer, fall, and winter, respectively, and averaged approximately 150 pg m(-2)day(-1). The total dry deposition flux was found to decrease as the temperature increased. Calculated dry deposition velocities of total PCDD/Fs were 0.45, 0.52, 0.32 and 0.39 cm s(-1) in spring, summer, fall, and winter, respectively, and averaged 0.42 cm s(-1).

1,2,3,6,7,8-hexachlorodibenzo- p -dioxin (1,2,3,6,7,8-HxCDD) and octachlorodibenzo- p -dioxin (OCDD) were photocatalytically degraded using immobilized TiO 2 , ZnO and SnO 2 films under ultraviolet (UV) with the wavelength between 300 and 450 nm. The specific surface areas of TiO 2 , ZnO and SnO 2 powders were calculated as 54.2, 4.6 and 4.8 m 2 /g, and the band gap energies were determined to be 3.17, 2.92 and 4.13 eV, respectively. The light source used had wavelengths between 300 and 450 nm, and the main wavelength was approximately 365 nm; hence, the smaller quantum efficiency of SnO 2 with wider band gap due to poor utilization of the UV light was expected. X-ray diffraction (XRD) revealed that sintered photocatalysts at 400 °C did not alter their characteristics. The first-order rate constants of OCDD in UV/TiO 2 , UV/ZnO and UV/SnO 2 were 5.30, 0.74 and 0.28 h −1 , respectively; those of 1,2,3,6,7,8-HxCDD in UV/ZnO and UV/SnO 2 were 3.28 and 3.19 h −1 , respectively. As expected, photodegradation rates declined as the number of chlorine atoms increased. Due to the low dosage (50 ng) of target compounds used, the amounts of Cl − and total organic carbon were too small for quantification. No 2,3,7,8-substituted congeners was identified during the photodegradation, and the UV/photocatalyst treatment might offer an effective treatment for PCDDs.

This study set out to identify possible PCDD/F emission sources for different atmospheric environments in a highly industrialized city located in southern Taiwan. We collected stack flue gas samples from five main stationary emission sources of the municipal solid waste incinerators (MSWIs), medical waste incinerators (MWIs), electric arc furnaces (EAFs), secondary aluminum smelters (ALSs), and sinter plants to assess the characteristics of their PCDD/F emissions. For mobile sources, congener profiles reported in U.S. EPA's database for unleaded gas-fueled vehicles (UGFV) and diesel-fueled vehicles (DFV) were directly adopted owing to lack of local data. The congener profiles of the 2,3,7,8-substituted PCDD/Fs were selected as the signatures of these PCDD/F emission sources. We conducted PCDD/F samplings on atmospheric environments of four categories, including background, residential area, traffic area, and industrial area. Through PCA and cluster analyses, we found that traffic areas were most influenced by PCDD/F emissions from UGFV and DFV, while those of industrial areas were mainly influenced by metallurgical facilities and MWIs. The above results were further examined by using the methodology of the indicatory PCDD/Fs. We confirmed that traffic areas were contributed by traffic sources, but industrial areas were simply affected by metallurgical facilities rather than MWIs. In conclusion, besides the use of PCA and cluster analyses, the methodology of the indicatory PCDD/Fs should be conducted for further validation in order to prevent misjudgment.

This study aims to characterize polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in the surrounding environment and workplace of a secondary aluminum smelter (secondary ALS). The mean I-TEQ concentrations in the stack flue gases and PCDD/F emission factor of the secondary ALS is 9.02 ng I-TEQ N m−3 and 50.1 μg I-TEQ ton-feedstock−1, respectively. The PCDD/F concentrations of outdoor (site O1, O2 and O3) and workplace air (site W1) during operation period are 0.670, 0.284, 0.141 and 0.571 pg I-TEQ N m−3, which are 3.3-, 2.1-, 1.8- and 2.5-fold higher than that during no operation period. The highest PCDD/F air concentrations (2.26 pg I-TEQ N-m−3) were measured at site W2 during furnace maintenance. The elevated PCDD/F air concentration (2.26 pg I-TEQ N m−3) caused by the fugitive particle during furnace maintenance implies that the PCDD/F concentration of air in the furnace that worker breathe could be extremely high. It reveals that PCDD/F exposure of furnace maintenance workers may be serious and further research on occupational exposure needs to be conducted.

A comprehensive sampling campaign was carried out around a municipal solid waste incinerator (MSWI) in central Taiwan in order to evaluate the impact of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) emissions on the ambient air and describe their spatial variation of gas–particle partitioning. Stack flue gas samples from the MSWI were also analyzed to investigate the relationship between the source and the impacted sites. Results showed that the PCDD/F emissions from the MSWI were a major source for PCDD/Fs in the ambient air. Moreover, PCDD/Fs in the ambient air tended to be distributed between the gaseous and particulate phases based on molecular weight; the higher chlorinated congener occupied a higher particulate fraction. There was an increase in the proportion of particle-bound PCDD/Fs with increasing distance from the MSWI. This observation supports the assumption that PCDD/Fs emitted were initially more associated with gaseous phase and the gaseous PCDD/Fs would gradually migrate to particles via either adsorption or absorption process. The results obtained were also applied and compared with the subcooled liquid vapor pressure (PL0)-based model and with the octanol–air partition coefficients (Koa)-based model. These two models were found to be excellent descriptors for the gas–particle partitioning of PCDD/Fs. Regressions for log partition coefficient (Kp) versus log PL0 and log Kp versus log Koa both demonstrated that PCDD/Fs were approaching equilibrium partitioning with increasing distance from the MSWI in the current study.

This study investigates the individual removal efficiencies of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) by venutri scrubber and bag filter, which operated in one medical waste incinerator (MWI) and one secondary aluminum smelter (secondary ALS), respectively. Stack flue gases, effluent, and fly ash were measured for PCDD/Fs to characterize the performance of the venutri scrubber and the bag filter for reducing PCDD/F emission. The mean PCDD/F concentrations in the stack flue gases of the MWI and secondary ALS were 0.511 and 10.6 ng I-TEQ Nm^(-3) (calculated according to International Toxic Equivalency Factors [I-TEQ] and normalized to dry flue gas conditions of 273 K and 11% O2), while concentrations in the effluent, including ash and wastewater from the venture scrubber and fly ash from the bag filter, were 7.51 ng I-TEQ g^(-1), 154 pg I-TEQ L^(-1), and 5.59 ng I-TEQ g^(-1), respectively. The average removal efficiencies of tetra-, penta-, hexa-, hepta-, and octa-PCDD/Fs by bag filter are 8.2%, 10.6%, 33.5%, 52.4%,and 59.1%, respectively. This suggests that highly chlorinated PCDD/Fs with lower vapor pressures are more easily adsorbed onto the particulate and consequently more easily removed by bag filter. The removal efficiencies of the bag filter on the total PCDD/F emission and the total PCDD/F I-TEQ emission are 37.6% and 11.2%, respectively, while whose of the venture scrubber are 46.0% and 44.5%, respectively. Although the operating conditions of the venutri scrubber and the bag filter are different, the removal efficiencies of each for PCDD/Fs is inadequate.

Heavy metals are one of the concerned pollutants emitted by the municipal waste incineration system (MWIs). The objective of this study was to evaluate the potential impact on local airborne metals from the emissions of an MWI. Aerosol samples were simultaneously collected at eight different sites around the municipal waste incinerator using PS-1 sampler. The concentrations of 16 elements (Mg, Al, Fe, Cu, Zn, Pb, Ti, V, Cr, Mn, Co, Ni, As, Cd, Ba and Hg) were quantified by inductively coupled plasma-mass spectrometry (ICP–MS) and atomic absorption spectrometer (AA). The profiles of the 16 metals in the surroundings of a municipal incinerator in central Taiwan were compared with those of the emission sources. The results showed that the profiles of multiple metals obtained at all sampling sites were similar to those emitted from the MWI stack. These findings suggested that the local airborne metal pollutants might probably derive from the stack emission of the MWI. Using cadmium as an index metal, it was found that the metals like Mg, Ti, V, Cr, Mn, Co, Ni, As, and Hg are highly influenced by the stack emission from the municipal incinerator. Moreover, the ratio of other metals to Cd that were increased with the distance from the incinerator. This might be due to the additional sources contributed to airborne metals following the emission from the incinerator and a difference in particle size of each particle-bound metal.

This study investigated four sinter plants, classified into two categories––with selective catalytic reduction (SCR) (S1, S2 and S3) and without SCR (S4) as its air pollution control device. Polychlorinated dibenzofurans (PCDFs) are dominant in the stack flue gases of sinter plants with and without SCR. The polychlorinated dibenzofurans/polychlorinated dibenzo- p -dioxins (PCDFs/PCDDs) ratio exceeds 1 extremely. The degree of chlorination of the sinter plant without SCR is towards hepta and hexa congeners while that of the sinter plant with SCR is towards penta and hexa congeners. PCDD/Fs are indeed decomposed (75.5% and 69% on ng and ng TEQ bases, respectively) and not only reduced in degree of chlorination. The overall concentration in the stack flue gas of sinter plants with SCR (7.97–14.1 ng/N m 3 ; 0.995–2.06 ng TEQ/N m 3 ) is lower than that of the sinter plant without SCR (28.9 ng/N m 3 ; 3.10 ng TEQ/N m 3 ). In Taiwan, based on the emission factors of 0.970 μg TEQ/ton-feedstock (sinter plants with SCR) and 3.13 μg TEQ/ton-feedstock (sinter plant without SCR), the annual PCDD/F emission of 44.7 g TEQ/year from sinter plants is 60 and 121 times higher than those from municipal solid waste incinerators (0.750 g TEQ/year) and MWIs (0.369 g TEQ/year). These results show that sinter plants have become the dominating PCDD/F emission source since tighter emission limits have been applied to incinerators.

a Abstract This study attempts to clarify the effects of chlorine content in waste on the formation mechanisms of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDyFs) in full scale incinerators by proposing and using the principal component analysis (PCA) to compare the congener profiles of PCDDyFs in the stack flue gases of 17 emission sources, including incinerators and vehicles. Four incinerators, among these 17 emission sources, were sampled and analyzed in this study, and the data for the other 13 emission sources were selected from previous studies. These 17 emission sources can be classified into four categories, including medical waste incinerators (MWIs, H1-H5), municipal solid waste incinerators (MSWIs, M1-M8), vehicle fuel combustion (unleaded gas-fueled vehicles, UGFV; diesel-fueled vehicles, DFV, ns2) and polyvinylchloride (PVC) facility vent combustors (PVC1 and PVC2, ns2). PCA was conducted for these emission sources with the fractions of 17 2,3,7,8-congeners in the stack flue gases as variables to clarify the effect of chlorine content in feeding wastes on the emission of PCDD yFs. From the results of PCA, we extrapolated that the threshold value of the chlorine content was at 0.8-1.1%, and the formation mechanisms of PCDDyFs are influenced first by whether the chlorine content in the feeding waste is over or below the threshold value then by other factors, which furnaces or APCDs represent. When the chlorine level in the waste is below the threshold value at 0.8-1.1%, the formation of PCDDs dominates, probably because the chlorine is used to chlorinate the non-substituted phenol to produce chlorophenols, which are important precursors for PCDDs. rather than chlorinate the dibenzofuran. While the chlorine level in the waste exceeds this threshold (0.8-1.1%), the rates of formation of PCDFs increase faster than those of PCDDs, probably because the chlorine content in the waste contributes to the deterioration of combustion conditions, and many products of incomplete combustion (PICs) like PAHs, will grow to a substantial level. When PCDDyFs are formed from PAHs, the formation rates of PCDFs are higher than those of PCDDs. 2002 Elsevier Science B.V. All rights reserved.

Emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from the stack flue gases of four medical waste incinerators (MWIs) and ten municipal solid waste incinerators (MSWIs) were investigated. The mean PCDD/F concentrations in the stack flue gases of these MWIs and MSWIs is 0.521 ng I-TEQ/Nm3 and 0.0533 ng I-TEQ/Nm3, respectively. In the stack flue gases of MWIs, OCDD, 1,2,3,4,6,7,8-HpCDD, 1,2,3,4,6,7,8-HpCDF and OCDF were the major congeners, while in MSWIs, OCDD and 1,2,3,4,6,7,8-HpCDD were the major ones. The mean PCDD/F emission factors (20.1 μg I-TEQ/ ton-waste) of the MWIs was about 210 times of magnitude higher than that of MSWIs, which was 0.0939 μg I-TEQ/ton-waste. In Taiwan, the annual emissions of PCDD/Fs from MWIs and MSWIs are 0.371 g I-TEQ/year and 0.737 g I-TEQ/year, respectively. Although the contribution of PCDD/Fs from MWIs to the atmosphere was 50.3% of that from MSWIs, it should be noted that most MWIs are equipped with a low stack and are situated in the proximity of the residential area and PCDD/F emissions from MWIs could significantly affect its surrounding environment.

This study was set out to characterize PCDD/F emissions from crematories and assess their impacts on the surrounding environment. Two crematories located in southern Taiwan were investigated, including the one (C1) with no air pollution control device installed and the other (C2) installed with a bag filter. Results show the mean PCDD/F emissions (11% oxygen) from the stacks of Cl and C2 were 2.36 and 0.322 ng I-TEQ Nm(-3), respectively. The mean emission factors for C1 and C2 were 13.6 and 6.11 microg I-TEQ body(-1), respectively. The removal efficiency of the bag filter on PCDD/Fs was 55.1%. The estimated PCDD/F emission rate for all crematories in Taiwan was 0.838 g I-TEG yr(-1) accounting for 227% and 112% of the annual emissions from all medical waste incinerators and municipal waste incinerators, respectively. The above results indicate that PCDD/F emissions from crematories were quite significant. To assess the impact of PCDD/F emissions from a crematory to the surrounding environment, ambient air samples were collected from the downwind site of C1 with the maximum ground concentration. We found the estimated maximum ground concentration at the downwind site of C1 (= 0.521 pg I-TEQ Nm(-3)) was much higherthan thatfound atthe background, rural area, residential area, urban area, and industrial area (= 0.006, 0.023, 0.052, 0.093, and 0.190 pg I-TEG Nm(-3), respectively). The above results suggestthat PCDD/F emissions from a crematory did significantly affect its surrounding environment. In conclusion, a proper control strategy should be taken immediately in order to eliminate PCDD/F emissions from crematories.

A side-chain liquid crystalline polysiloxane polymer (PS3DBDE1) with high purity and high isotropic transition temperature served as a stationary phase in an attempt to chromatographize the dioxin/furan compounds. The polymer was coated on the inner surface of a 0.25 mm I.D. capillary column by using the static coating method, forming a film with a thickness of df approximately 0.25 microm. A commercial standard solution (US EPA 1613 standard solution 1613CS4) containing polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) was used to test the chromatographic behavior of the laboratory-made capillary column. Two commercial capillary columns HP-5MS (Hewlett-Packard) and RTX-5MS (RTX) were chosen to compare their chromatographic behavior. The results show that by the use of PS3DBDE1 the isomeric pair compounds 1,2,3,4-TeCDD vs. 2,3,7,8-TeCDD and 1,2,3,4,7,8-HxCDD vs. 1,2,3,6,7,8-HxCDD and the same substituted-chlorine number compounds 1,2,3,4,6,7,8-HpCDF vs. 1,2.3,4,6,7,8-HpCDD and 1,2,3,4,6,7,8,9-OCDD vs. 1,2,3,4,6,7,8,9-OCDF had higher resolution than HP-5MS and RTX-5MS as suggested by the column makers.

Catalytic incineration is one of the cost-effective technologies to solve the troublesome volatile organic compounds (VOCs). However, some sulfur containing VOCs, such as dimethyl sulfide, may deactivate the Pt catalyst that is commonly used in the catalytic incineration process. This paper provides information on the poisoning effect of (CH3)2S. The catalytic incineration of (CH3)2S, typically emitted from the petrochemical industry, over a Pt/Al(2)O(3) fixed bed catalytic reactor was studied. The effects of operating parameters including inlet temperature, space velocity, (CH3)2S concentration, O2 concentration and catalyst size were characterized. Catalytic incineration on a mixture of (CH3)2S with CH(3)SH was also tested. The results show that the conversions of (CH3)2S increase as the inlet temperature increases and the space velocity decreases. The higher the (CH3)2S concentration is, the lower its conversion is. The O2 concentration has a positive effect on the conversion of (CH3)2S. (CH3)2S has a poisoning effect on the Pt/Al(2)O(3) catalyst, especially at lower temperatures. The conversion of (CH3)2S is significantly suppressed by the existence of CH(3)SH.

This manuscript proposes a packing arrangement model for a co-mesogenic sidechain liquid crystalline copolysiloxane polymer copoly[4-allyloxy-benzoic acid [4′-2-(2-methoxyethoxy) ethoxy] biphenyl]-4-y1 ester-co-4-allyloxy-[(4-cyano)-4′-phenyl] carboxyl benzoate ester (copoly [(MS3BDBE2)-co-(MCN)]x/y depending on the relative molar composition of each mesogen. From the analysis of the thermal data, X-ray diffraction data, and solid state NMR spin-lattice relaxation (T1ρ H) data, we have found two side chain molecules in the mesophase layer coming from the same or a different polymer backbone. They are presumed to be mixed and form a bilayer smectic C mesophase at lower MCN concentrations as well as at higher MCN concentrations.

Two new and high-purity all-hydrocarbon side-chain liquid crystalline polysiloxane polymers were synthesized by grafting all-hydrocarbon liquid crystal monomers onto a polymethylhydrosiloxane backbone. The two polysiloxane polymers show both smectic B and E mesophases which were characterized by (differential scanning calorimetry and X-ray analysis. As stationary phases, these liquid crystalline polysiloxane polymers were coated on the inner surface of a capillary column (i.d. = 0.32 mm, film thickness d(f) ≈ 0.25 μm) using the static coating method. The capillary column was installed on a GC/MS instrument. We used a standard commercial mixture of 21 species of polynuclear aromatic hydrocarbons (purchased from Supelco Co. and Merck Co.) to test the chromatographic behavior of the coated stationary phase. Test results of the isomeric pair compounds show a better separation resolution than identical tests using the commercial HP-5 capillary column, which is a standard and state-of-the-art analytical tool for the chromatographic resolution of PAHs.

Catalytic incineration was one of the cost-effective technologies to solve the troublesome VOCs. However, some sulfur containing VOCs, such as dimethyl disulfide, may deactivate the Pt catalyst that was commonly used in the catalytic incineration process. This article provides information on the poisoning effect of dimethyl disulfide. The catalytic incineration of dimethyl disulfide and ethanol, typically emitted from the petrochemical industry, over a Pt/Al 2 O 3 fixed bed catalytic reactor were studied. The effects of operating parameters including inlet temperature, space velocity, VOCs concentration, O 2 concentration and catalyst size were characterized. Catalytic incineration on a mixture of dimethyl disulfide and ethanol was also tested. The results show that the conversions of C 2 H 5 OH and (CH 3 )S 2 increase as the inlet temperature increases and the space velocity decreases. The higher the C 2 H 5 OH concentration is, the higher its conversion is. However, the reverse is true for the case of (CH 3 ) 2 S 2 . The O 2 concentration has no effects on the conversion of C 2 H 5 OH but has a positive effect on the conversion of (CH 3 ) 2 S 2 . (CH 3 ) 2 S 2 has a poisoning effect on the Pt/Al 2 O 3 catalyst, especially at a lower temperature. The conversion of C 2 H 5 OH is significantly suppressed by the existence of (CH 3 ) 2 S 2 at a temperature lower than 300°C.

Synthesis, Characterization, and Mesomorphic Behavior of Terminally Carboxyl Oligo(ethylene oxide) Monomethyl Ethers-Substituted Side Chain Liquid Crystalline Copolysiloxane Polymers

The syntheses and characterizations of poly [4-allyloxy-benzoic acid [4′-(2-methoxy) ethoxy] biphenyl]-4-yl ester-co-4-allyloxy-[(4-cyano)-4′-phenyl] carboxyl benzoate ester (poly [(MS3BDBE1)-co-(MCN)]x/y) (where x/y represents the molar ratio of the two structural units on the side chain) were performed in this study. The molar compositions of the structural units on the copolymers side chain were characterized by1H NMR. The transition temperatures, mesophase texture, and layer spacing (dl) of the polysiloxane polymers and copolymers were determined by differential scanning calorimetry (DSC), polarized optical microscopy, and X-ray diffraction patterns. The effects of the molar composition in the copolymers on the mesophase texture, transition temperatures, enthalpy/entropy change of mesophase/isotropic transition, dl of these copolymers were also discussed.

In this study, ambient air samples from different atmospheric environments were examined for both PBDE and PCDD/F characteristics to verify that combustion is a significant PBDE emission source. The mean ± SD atmospheric PBDE concentrations were 165 ± 65.0 pg Nm(-3) in the heavy steel complex area and 93.9 ± 24.5 pg Nm(-3) in the metals complex areas, 4.7 and 2.7 times higher than that (35.3 ± 15.5 pg Nm(-3)) in the urban areas, respectively. The statistically high correlation (r=0.871, p

Here we show that combustion sources, including waste incinerators, metallurgical processes, power-heating systems and so on, are also important emitters of polybrominated diphenyl ethers (PBDEs) to the atmosphere. Geometric mean PBDE concentrations in the stack flue gases of the combustion sources ranged from 8.07 to 469 ng/Nm3. The sinter plants (24.7 mg/h), electric arc furnaces (EAFs) (11.3 mg/h) and power plants (50.8 mg/h) possessed the largest PBDE emission rates, which were several orders higher than those of the other reported sources. The occurrences of the PBDEs in the flue gases of the power plants and vehicles, as well as their PBDE concentrations statistically highly correlated with combustion-originated PCDD/Fs, revealing that PBDEs should be the products of combustion. The ranking of major PBDE emission sources in Taiwanese PBDE inventory for combustion sources was power plants (30.85 kg/year), vehicles (14.9 kg/year) and metallurgical processes (5.88 kg/year).

Dioxins comprise a group of compounds which contain a double aromatic ring-like structure. They are among the most prevalent and toxic environmental pollutants. Accumulation of dioxins in human tissues poses a potential threat to human health. Currently, analytical chemical procedures dominate dioxin-detection protocols. In this study, we established a fluorescence resonance energy transfer (FRET)-based dioxin-detection bioassay. Aryl hydrocarbon receptor (AHR) and AHR nuclear translocator (ARNT) fused-cyan fluorescent protein (CFP) and -yellow fluorescent protein (YFP) constructed were transiently co-transfected into rat hepatoma cell line, H4IIEC3 cells. Our results showed that no FRET signals were detected in AHR-CFP- and ARNT-YFP-transfected H4IIEC3 cells. However, dioxin treatments upregulated FRET signals in these transfected cells in a dose-dependent manner. This work highlighted the potential of FRET technique in the detection of dioxin-like compounds.

The objectives of this study were first to set up and validate the quality criteria of the Xenobiotic Detection Systems—chemical activated luciferase gene expression (CALUX) bioassay for the analysis of cow's milk samples spiked with polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). The application of this bioassay was then tested by analyzing 28 commercially available pasteurized milk samples and comparing the data with the reference method for PCDD/F analysis. The CALUX criteria from the U.S. EPA and the European Union (EU) were calculated from 16 replaced spiked milk (SM) samples and 8 performance evaluation (PE) samples to validate the CALUX bioassay system. The CALUX bioassay criteria included control chart for quality control (QC) standards, recovery efficiency, and data comparability. The control chart for QC standards were both within the μ ± 2σ range. The recovery efficiencies ranged from 60.4% to 106% with an average of 79.9% (relative standard deviation (RSD): 20.7%). The mean of data comparability (i.e., relative percent difference, RPD) between CALUX bioassay and high-resolution gas chromatography and high-resolution mass spectrometry (HRGC/HRMS) was 19.0% for SM samples. For the PE samples, Pearson's correlation coefficient between CALUX and the HRGC/HRMS method was 0.953. The high correlation shows that the CALUX system is suitable as a screening method and a semi-quantitative method to analyze the PCDD/F concentration in milk samples. Next, the validated CALUX bioassay was applied to measure 28 commercially available pasteurized milk samples. These milk samples were also analyzed with the HRGC/HRMS method to compare the analysis data from two different methods. There is no false negative sample when applying the bioassay to pasteurized milk and PE samples as a screening method and a semi-quantitative method. The present study indicates that CALUX is a powerful bioassay method for screening a large number of milk samples.

This study investigates the emissions of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) from four electric arc furnaces (EAFs) and eight secondary aluminum smelters (secondary ALSs) in Taiwan. The mean PCDD/F International-Toxicity Equivalents (I-TEQ) concentrations in the stack gases of these EAFs and secondary ALSs are 0.28 ng I-TEQ/Nm3 (relative standard deviation [RSD]= 100%) and 3.3 ng I-TEQ/Nm3 (RSD = 260%), respectively. The high RSDs, especially for those obtained from secondary ALSs, could be caused by the intrinsic differences in their involved feeding materials, furnace operating conditions, and air pollution control devices. The mean I-TEQ emission factor of PCDD/Fs for EAFs (1.8 microg I-TEQ/tonne-feedstock) is lower than that for secondary ALSs (37 microg I-TEQ/tonne-feedstock). This result might be because the involved furnace temperatures for secondary ALSs (650-750 degrees C) are lower than those for EAFs (1600-1700 degrees C), resulting in the deterioration of the combustion condition, leading to the formation of PCDD/Fs during the industrial process. This study found that the total PCDD/F emissions from EAFs (20 g I-TEQ/yr) and secondary ALSs (18 g I-TEQ/yr) are approximately 27, 53, and approximately 24, 49 times higher than those from municipal solid waste incinerators (MSWIs; 0.74 g I-TEQ/yr) and medical waste incinerators (MWIs; 0.37 g I-TEQ/yr), respectively; while those are 44 and 40% of total PCDD/F emission from sinter plants (45 g I-TEQ/ yr), respectively. Considering a more stringent emission limit has been applied to waste incinerators (0.1 ng I-TEQ/Nm3) in Taiwan lately, the results suggest that the control of the emissions from metallurgical processes has become the most important issue for reducing the total PCDD/F emission from industrial sectors to the ambient environment.

This study examined the direct photolysis and photocatalytic processes for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and 1,2,3,6,7,8-hexachlorodibenzo-p-dioxin (1,2,3,6,7,8-HxCDD). The photocatalytic procedure was performed on the TiO2 film under irradiation with 365 nm UV and the compounds were immobilized on TiO2/solid phase. No 2,3,7,8-substituted PCDD/Fs products were detected in photocatalytic process under the experimental conditions. The reaction rate constants were 0.3256 h−1 for 2,3,7,8-TCDD (2000 ng) in UV/TiO2 reaction, 0.2474 h−1 for 1,2,3,6,7,8-HxCDD (2000 ng) in UV/TiO2 reaction and 0.0666 h−1 for 1,2,3,6,7,8-HxCDD (50 ng) under direct UV irradiation. For 1,2,3,6,7,8-HxCDD (50 ng) in a UV/TiO2 reaction, the degradation is too fast to determine the reaction rate. The photocatalytic process was faster than direct photolysis for the same chlorinated PCDDs, and the rate decreased with increasing PCDDs quantity. The photocatalytic rate of the PCDDs decreased with increasing chlorination extent. The confirmed intermediates of 1,2,3,6,7,8-HxCDD in direct photolysis, 1,2,3,7,8-PeCDD and 2,3,7,8-TCDD both were formed by the loss of a longitudinal chlorine nearest the oxygen atom. The quantity of 1,2,3,7,8-PeCDD and toxic equivalency quantity (TEQ) declined after 10 h of UV irradiation. The proposed dechlorination pathway of 1,2,3,6,7,8-HxCDD was via 1,2,3,7,8-PeCDD to 2,3,7,8-TCDD. Formation of trace concentrations of 1,2,3,4,7,8-hexachlorodibenzo-p-dioxin (1,2,3,4,7,8-HxCDD) and 1,2,3,7,8,9-hexachlorodibenzo-p-dioxin (1,2,3,7,8,9-HxCDD) from 1,2,3,6,7,8-HxCDD appears to be a minor side reaction.

The crystal and molecular structures of the mesogenic monomer 3-[4-(4'-ethylbiphenyl)]1-propene, molecular formula CH3-CH2-C6H4-C6H4-CH2-CH=CH2, has been determined by X-ray diffraction analysis at 293(2) K. The compound crystallizes in the form of a noncentrosymmetric monoclinic system, space group Pc, with two molecules per cell. The cell parameters are a = 13.90(5)A, b = 5.75(1)A, c =9.54(5)A and β = 116.1(3)°. Refinement leads to R = 0.0554. Both phenyl rings adopt boat conformations and are nearly coplanar. The molecules form a smectic-like layer structure in the crystalline state.