Photolysis study of perfluoro-2-methyl-3-pentanone under natural sunlight conditions

The UV-vis and infrared absorption cross sections of perfluoro-2-methyl-3-pentanone (CF3CF2C(O)CF(CF3)2, 1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)-3-penta none), has been obtained, and a photolysis study was carried out under natural sunlight conditions in the European simulation chamber, Valencia, Spain (EUPHORE). The photolysis loss rate, J(photol), equaled (6.4 +/- 0.3) x 10(-6) s(-1) in the period of 10-14 GMT, July 14, 2003 in Valencia (0.5 W, 39.5 N) and corresponded to an effective quantum yield of photolysis of 0.043 +/- 0.011 over the wavelength range of 290-400 nm; the error limits correspond to 2sigma from the statistical analyses. The atmospheric lifetime of CF3CF2C(O)CF(CF3)2 is estimated to be around 1 week, and the global warming potential of the compound is negligible.     

Oxidative stability of previously frozen ostrich Muscularis iliofibularis packaged under different modified atmospheric conditions

This study investigated the aptness of modified atmospheric packaging (70:30, O₂:CO₂ (O_MAP); 70:30, N₂:CO₂ (N_MAP)) and traditional overwrap (control) for previously frozen ostrich steaks, stored at 4 ± 1 °C for 10 days. The N_MAP showed the least oxidation, O_MAP the highest and the control moderate. The redness (CIE a*) decreased to 3.67 ± 0.83 by day 10 in the O_MAP, the N_MAP and control initially had lower values indicating slower oxidisation. The free carbonyl production was higher in the O_MAP than the N_MAP and control. TBARS remained relatively constant for the N_MAP and control, but increased to 9.70 ± 3.26 (day 10) in the O_MAP. Drip loss (non‐cumulative), was initially high (5–6%) for N_MAP and control, followed by a decrease on day 2 (2%) that increased to day 10 (4–6%). In conclusion, the traditional overwrap was not suited; N_MAP holds potential under a true anoxic atmosphere whilst O_MAP was limited by protein and lipid oxidation.     

Vibrio parahaemolyticus growth under low-iron conditions and survival under high-magnesium conditions

Since 1996, Vibrio parahaemolyticus serotype O3:K6 and closely related strains have been associated with an increased incidence of V. parahaemolyticus gastroenteritis worldwide, suggesting the emergence of strains with enhanced abilities to cause disease. One hypothesis for the recent emergence of V. parahaemolyticus O3:K6 and related strains is an enhanced capacity for environmental survival relative to other strains, which might result in increased human exposure to these organisms. Therefore, the objective of this study was to test the hypothesis that survival or growth characteristics of clinical V. parahaemolyticus isolates differ from those of nonclinical isolates under different environmental conditions. Twenty-six V. parahaemolyticus isolates selected to represent either clinical or food sources were monitored for either survival following exposure to high magnesium (300 mM) or growth under iron-limited conditions. Isolates in each category (clinical or food) differed widely in survival capabilities following 24 h of exposure to 300 mM Mg2+. Although 4 of 15 clinical isolates grew better at approximately 0.96 microM Fe2+ (iron-limited conditions) than at 50 microM Fe2+ (iron-rich conditions), as an entire group clinical isolates in this study were not more effective at growing under iron-limited conditions than were strains not associated with disease. Within the diverse collection of strains examined in these experiments, neither growth characteristics in low-iron environments nor survival capabilities following exposure to high magnesium concentrations were uniformly different between clinical and nonclinical V. parahaemolyticus isolates. Therefore, neither phenotypic characteristic can be used to reliably differentiate potentially pathogenic V. parahaemolyticus strains.     

Protein and lipid oxidative stability of fresh ostrich M. Iliofibularis packaged under different modified atmospheric packaging conditions

This study investigated the aptness of modified atmospheric packaging (70:30, O₂:CO₂ (O_MAP); 70:30, N₂:CO₂ (N_MAP)) and traditional overwrap (control) for fresh ostrich steaks, stored at 4 ± 1 °C for 10 days. N_MAP showed the least oxidation, O_MAP the highest and the control moderate. Myoglobin (CIE a^∗) was gradually oxidised in all packaging atmospheres, but the O_MAP oxidised at the slowest rate, remaining significantly more bloomed from day 0 (17.86 ± 1.17) to 8 (9.78 ± 1.12). Free carbonyls were constant in all packaging environments. TBARS remained constant for the N_MAP (2.39 ± 0.21 mg MDA/kg meat) and the overwrap (3.06 ± 0.29 mg MDA/kg meat), but the O_MAP increased significantly (9.96 ± 1.02 mg MDA/kg meat) to day 10. The pH increased in the control but remained constant in the MAP treatments. The control also showed the greatest drip loss (>5%). The success of MAP application to ostrich will depend on the ability of the consumer to detect the by-products of lipid oxidation.     

微波条件下的美拉德反应

研究了微波条件下不同中性氨基酸与葡萄糖、果糖的美拉德反应(Maillard reaction,MR)。结果得出,甘氨酸无论是在酸性还是碱性条件下的呈色速率最快;果糖、葡萄糖美拉德反应得到的金黄色、红棕色产物,在280nm左右的吸收强度,葡萄糖均小于果糖;在酸性条件下,丙氨酸、苏氨酸参与的美拉德反应生成的吡嗪类化合物种类最多。     

Intestinal flora under conditions of stress

In healthy probands influenced by endocrinic stress (application of ACTH, growth hormone, and triiodothyronine) the microflora of the content of the duodenum and of the feces is examined. After three weeks, only, rising numbers of bacteria could be detected in the duodenal content. The number of the aerobic bacteria, mainly of the coliforms in the feces, decreased whereas the number of the anaerobic germs increased. This stress model seems to be suitable for such researches.     

Export of arsenic from forested catchments under easing atmospheric pollution

Massive lignite burning in Central European power plants peaked in the 1980s. Dissolved arsenic in runoff from upland forest ecosystems is one of the ecotoxicological risks resulting from power plant emissions. Maxima in As concentrations in runoff from four forest catchments have increased 2-5 times between 1995 and 2006, and approach the drinking water limit (10 microg L(-1)). To assess the fate of anthropogenic As, we constructed input/output mass balances for three polluted and one relatively unpolluted forest catchment in the Czech Republic, and evaluated the pool size of soil As. The observation period was 11 years, and the sites spanned a 6-fold As pollution gradient. Two of the polluted sites exhibit large net As export via runoff solutes (mean of 4-5 g As ha(-1) yr(-1) for the 11-year period; up to 28 g As ha(-1) yr(-1) in 2005). This contrasts with previous studies which concluded that forest catchments are a net sink for atmogenic arsenic both at times of increasing and decreasing pollution. The amount of exported As is not correlated with the total As soil pool size, which is over 78% geogenic in origin, but correlates closely with water fluxes via runoff. Net arsenic release is caused by an interplay of hydrological conditions and retreating acidification which may mobilize arsenic by competitive ligand exchange. The effects of droughts and other aspects of climate change on subsequent As release from soil were not investigated. Between-site comparisons indicate that most pollutant As may be released from humus.     

Effect of potential atmospheric warming on temperature-based indices describing Australian winegrape growing conditions

Background and Aims:  This paper describes the changes in temperature-based indices used to classify viticultural climates in Australia for three warming scenarios produced by the Commonwealth Scientific and Industrial Research Organisation: Mk3.0 global climate model for the years 2030, 2050 and 2070.
Methods and Results:  Temperature indices that describe grapevine growing season temperature (GST), ripening period temperature, accumulated biologically effective degree days and growing season length were calculated to produce maps of Australia for each warming scenario. Summary statistics of each index's median and range are presented for each Australian wine region under each warming scenario. The greatest change in GST (above the 1971–2000 mean) was modelled to occur for the Perth Hills region, increasing by 1.0°C by 2030, 1.9°C by 2050 and 2.7°C by 2070. The least change in GST was modelled to occur for the Kangaroo Island region, increasing by 0.5°C by 2030, 0.9°C by 2050 and 1.3°C by 2070.
Conclusion:  Of the 61 recognised wine regions, a median GST of over 21°C (an indicator of the limit of quality wine grape production conditions) was found for three regions for the period 1971–2000, for eight regions for the 2030 scenario, 12 regions for the 2050 scenario and 21 regions for the 2070 scenario.
Significance of the Study:  Without appropriate adaptations, some established viticultural regions of Australia may become less suitable for quality winegrape production, whereas regions that were once considered unsuitable for quality winegrape production may become more suitable.     

超声波在牛仔布酶洗整理中的应用

采用单因素分析法,研究超声波环境下纤维素酶对牛仔布的仿旧整理工艺及整理效果,探讨超声波功率、超声波处理时间、处理温度、纤维素酶质量浓度、溶液的pH值和占空比值对牛仔布洗水效果的影响;测试了洗水前后牛仔布的K/S值和减量率。结果表明,超声波环境下纤维素酶对牛仔布仿旧整理的最佳工艺条件为:超声波处理功率400 W,处理时间20 min,处理温度60℃,纤维素酶质量浓度为3 g/L,溶液pH值为4.5,占空比为0.4。     

Reoxidation of bioreduced uranium under reducing conditions

Nuclear weapons and fuel production have left many soils and sediments contaminated with toxic levels of uranium (U). Although previous short-term experiments on microbially mediated U(VI) reduction have supported the prospect of immobilizing the toxic metal through formation of insoluble U(IV) minerals, our longer-term (17 months) laboratory study showed that microbial reduction of U can be transient, even under sustained reducing conditions. Uranium was reduced during the first 80 days, but later (100-500 days) reoxidized and solubilized, even though a microbial community capable of reducing U(VI) was sustained. Microbial respiration caused increases in (bi)-carbonate concentrations and formation of very stable uranyl carbonate complexes, thereby increasing the thermodynamic favorability of U(IV) oxidation. We propose that kinetic limitations including restricted mass transfer allowed Fe-(III) and possibly Mn(IV) to persist as terminal electron acceptors (TEAs) for U reoxidation. These results show that in-situ U remediation by organic carbon-based reductive precipitation can be problematic in sediments and groundwaters with neutral to alkaline pH, where uranyl carbonates are most stable.     

Stability of lutein under various storage conditions

The stability of lutein, a major xanthophyll, was investigated under various storage conditions. Continuous exposure of lutein-containing samples to cold white fluorescent light (4600 lux) at 25 °C resulted in the degradation of lutein at 0.8%-10.7% per day in the samples containing ascorbic acid, ascorbic acid + KOH and H₂O (as control) over a period of 75 days. It was found that ascorbic acid could retard lutein degradation (0.04% - 2.5% per day) at temperatures from ?30 °C to 50 °C under the alkaline condition in darkness. High temperature promoted the degradation of lutein in all the samples. Under the alkaline condition and at low temperature (-12 °C), the stability of pure lutein was similar to that of the lutein extracted from the alga Chlorella protothecoides cultivated heterotrophically.     

Bioremediation of 2,4,6-trinitrotoluene under field conditions

In situ bioremediation of the nitroaromatic explosive 2,4,6-trinitrotoluene (TNT) provides a cost-effective alternative for cleaning up contaminated sites. Here we compare the effectiveness of several bioremediation techniques: natural attenuation, bioaugmentation with TNT-degrading Pseudomonas putida JLR11, phytoremediation with maize (Zea mays L.) and broad beans (Vicia faba L.), and rhizoremediation with maize and broad beans inoculated with P. putida JLR11. Experiments in spiked hydroponic medium demonstrated that inoculation with bacteria did not affect TNT levels. On the other hand, axenic plants were able to remove 32% to 38% of the TNT from the medium. However, when plants were inoculated with bacteria,TNT disappeared to an even greater extent (80% to 88%), a result that advocates a role for P. putida JLR11 in rhizoremediation. In field experiments neither natural attenuation nor bioaugmentation with P. putida JLR11 affected TNT levels to a significant degree. However, the extractable TNT content in rhizosphere soil associated to maize roots decreased by more than 96% in 60 days regardless of inoculation. This indicates that under these field conditions, the effect of phytoremediation by maize overshadowed any effect of rhizoremediation by P. putida JLR11.     

Preservation of tomato juice under acid conditions

A technique for preserving tomato juice and crushed tomatoes under acid conditions has been developed. This eliminates the need for the usual processing time of 55 min in boiling water for 650 ml glass bottles, which would result in considerable savings in energy requirements by the tomato processing industry. The ketchup prepared from the acidified tomato juice and crushed tomatoes (after neutralisation) was rated by the panelists to be as good as a commercial tomato ketchup sample.     

Effects of long periods under grass on soils under british conditions

The effects of long periods (up to many centuries) under grass on 34 mineral soils have been studied by contrasting their physical and other characteristics with the same soils which had a predominantly arable history in living memory. The old grassland soils contain more organic matter (as measured by total nitrogen), more total pore space, aggregates of greater water-stability, hold more water both at the sticky point and the lower plastic limit, contain more worms but have a smaller bulk (or apparent) density. A highly significant (P = 0.7%) correlation was shown between the nitrogen level and the clay content of the old grassland soils. A significant (P = 1.5%) correlation was found between the water-stability of the old grassland soil aggregates and their clay content but not with the nitrogen level (P = 5.3%).     

Catalyzed degradation of azo dyes under ambient conditions

Phase-pure layered perovskite La(4)Ni(3)O(10) powders were synthesized by a solution combustion approach. It is found that, in the presence of the La(4)Ni(3)O(10) powders, aqueous azo dyes can be degraded catalytically and efficiently under ambient conditions. Neither light nor additional reagents are needed in the catalytic reaction. The dye degradation procedure can be accelerated markedly by magnetic stirring. A systemic series of chemical and electrochemical experiments suggested that the dye degradation proceeds through electron transfers from the dye molecules to the catalyst and then to electron acceptors such as dissolved oxygen. The present catalytic degradation requires no additional reagents or external energy input, which hence provides a potentially low-cost alternative for the remediation of azo-dye effluents.     

不同处理条件对乳铁蛋白抑菌性的影响

对不同处理条件下乳铁蛋白(Lactoferrin LF)的抑菌性进行了研究.结论表明:LF经过70 ℃以下的巴氏杀菌,不会影响到其抑菌活性.LF在弱碱性的条件下抑菌效果最好,环境pH值的变化时,LF针对金黄色葡萄球菌的抑菌活性变化较大,在pH值为6～10之间,LF对沙门氏菌有抑菌效果.LF在人工胃液中抑菌效果明显增加.