柳河流域特征污染物负荷模拟及污染源解析

基于通用流域负荷模型(GWLF模型),选取柳河流域为研究对象,利用2006-2014年的水文水质数据进行水文化学过程的模拟,评估流域节点断面的月径流量及特征污染物负荷通量,根据模型结果分析了特征污染物的污染来源及贡献率。结果表明,从年际变化上看,COD、氨氮和总氮的总负荷通量近年来有所下降,总磷的总负荷通量呈逐年上升趋势。从年均水平上看,COD、氨氮的点源污染与非点源污染贡献率相差不大,均接近50%;总氮的非点源污染贡献率远远高于点源污染,贡献率高达79.6%;总磷的污染来源主要为点源污染,贡献率高达74.9%。根据特征污染物的污染源解析结果,提出有针对性的削减和控制污染的措施,为流域水污染管控提供依据。     

PHYSICAL CHARACTERISTICS AND ACCEPTABILITY OF EXTRUDED AFRICAN BREADFRUIT-BASED SNACKS

ABSTRACT

Five‐level combinations of African breadfruit, corn and soybean, in the ratios 40:5:55; 55:5:40; 70:5:25; 85:5:10 and 100:0:0%, respectively, were hydrated to 15, 18, 21, 24 and 27% and extruded into snacks at screw speeds of 100, 120, 140, 160 and 180 rpm. Physical characteristics of snacks from blends containing 15 and 18% moisture ranged from thin‐smooth to thin‐fine‐smooth pellets. Those containing 21 to 27% moisture were either thin‐smooth or thick‐smooth, fine‐smooth or rough strands. Feed moisture and feed composition were the most significant process variables influencing physical and sensory characteristics. The optimum process variable combination that had maximum influence on physical and sensory characteristics of snacks was the 70:5:25 feed ratio with 21% moisture and extruded at 140 rpm. This resulted in an overall acceptability score of 8.20 on a 9‐point hedonic scale.

PRACTICAL APPLICATIONS

African breadfruit is widely grown in the high rainforest parts of Nigeria and other African countries, where the seeds are traditionally consumed as porridge meal when cooked with ingredients or as snacks when roasted. There is therefore a need to adopt more efficient extrusion technologies to rapidly and efficiently transform African breadfruit and its blends with corn and soybean into acceptable snacks. Optimizing process variable conditions using response surface analysis to evaluate product physical characteristics and acceptability was the thrust of this study. It is expected to give direction toward a more scientific approach to scaling up operations in African breadfruit seed processing and utilization.

     

Atlantic salmon skin and fillet color changes effected by perimortem handling stress, rigor mortis, and ice storage

ABSTRACT:  The changes in skin and fillet color of anesthetized and exhausted Atlantic salmon were determined immediately after killing, during rigor mortis, and after ice storage for 7 d. Skin color (CIE L *, a *, b *, and related values) was determined by a Minolta Chroma Meter. Roche Salmo Fan™ Lineal and Roche Color Card values were determined by a computer vision method and a sensory panel. Before color assessment, the stress levels of the 2 fish groups were characterized in terms of white muscle parameters (pH, rigor mortis, and core temperature). The results showed that perimortem handling stress initially significantly affected several color parameters of skin and fillets. Significant transient fillet color changes also occurred in the prerigor phase and during the development of rigor mortis. Our results suggested that fillet color was affected by postmortem glycolysis (pH drop, particularly in anesthetized fillets), then by onset and development of rigor mortis. The color change patterns during storage were different for the 2 groups of fish. The computer vision method was considered suitable for automated (online) quality control and grading of salmonid fillets according to color.     

Wind power in Brazil—transition using German experience

The development of the installed capacity of wind energy converters in Germany shows that a significant increase of its contribution to the energy supply is possible, depending on the measures introduced by the state. In contrast to Germany, Brazil has not been very concerned about its greenhouse gas emissions yet, as more than 90% of the electricity is generated by hydropower. However, due to the current energy crisis Brazil has to search for alternatives in order to stabilize the energy matrix and diminish the dependence on precipitation, especially as a new capacity of about 4 GW has to be installed each year. The intention of the authors is to present the German conditions that led to the current favorable situation for wind energy and to compare these to the Brazilian circumstances that exist for an extended application of this energy source. At the same time special attention is paid to the newest legal developments in Brazil.     

Rural area power supply in Nigeria: A cost comparison of the photovoltaic, diesel/gasoline generator and grid utility options

A large proportion of the population of Nigeria reside in the rural communities. In this work, the financial costs of providing centralized (photovoltaic) PV generating system of various capacities—to satisfy different load requirements—in a remote village in Nigeria is compared with the cost of grid extension over a distance of 1.8 km. Comparison is also made with the centralised diesel generator power supply option. In addition, the costs of decentralised PV home systems are compared with those of decentralised gasoline generator systems. For all the systems, the initial capital costs and the life cycle costs over a 20-year life cycle are reported. Sensitivity analysis was performed using variations in module costs, diesel fuel prices and grid extension distance. The results suggest that PV has a remarkable potential as a cost-effective option for low-power electrical energy supply to the rural communities in the country.     

釜用集装式静环偏心机械密封

针对立式顶部驱动聚合反应釜机械密封密封端面工作条件比较恶劣、往往处于干摩擦及边界摩擦且端面磨损较大的特点 ,分析了偏心机械密封的特点和设计依据 ,提出了改进的釜用集装式静环偏心结构机械密封     

Studies on the milk composition of West African dwarf, Red Sokoto and Saanen goats at different stages of lactation. I. Total solids, butterfat, solids-not-fat, protein, lactose and energy contents of milk.

Nine West African dwarf (Fouta djallon), Red Sokoto (Maradi) and Saanen lactating goats, hand-milked, were used for these studies, which lasted 12 weeks. The Saanen goat's milk was obtained weekly from the Western State Ministry of Agriculture and Natural Resources Urban Dairy Farm at Iwo Road, while similar samples were collected from the herd at the University of Ibadan Teaching and Research Farm. The goats were balanced for stage of lactation, namely early, mid- and late-lactation. They were each maintained on giant star grass (Cynodon nlemfuensis) ad lib. and 1 kg dairy concentrate mixture daily. The mean contents, with standard deviations, of the milks of Saanen, West African dwarf and Red Sokoto goats at mid-lactation respectively were: (in percentages), total solids 12-25 plus or minus 0-078, 18-18 plus or minus 0-392, 15-85 plus or minus 0-077; solids-not-fat (SNF) 8-91 plus or minus 0-42, 10-48 plus or minus 0-471, 10-53 plus or minus 0-140; butterfat 3-34 plus or minus 0-141, 7-78 plus or minus 0-621, 5-32 plus or minus 0-098; protein 3-04 plus or minus 0-139, 5-30 plus or minus 0-292, 4-74 plus or minus 0-021; lactose 4-56 plus or minus 0-167, 5-19 plus or minus 0-176, 4-77 plus or minus 0-053; energy (kj/g dried milk), 21-08 plus or minus 1-11, 25-51 plus or minus 1-74, 22-17 plus or minus 0-51. Breed differences were significant (P less than 0-01). The milk of West African dwarf goats contained more of these milk components than the milk of the Red Sokoto or Saanen goats. The Red Sokoto goats gave milk of higher content than did Saanen goats, even at an early stage of lactation. Butterfat, protein, lactose and energy values were significantly affected by stages of lactation (P less than 0-05) and tended to rise with advancing lactation; this was particularly so with West African dwarf goats.     

Two-photon fluorescence absorption and emission spectra of dyes relevant for cell imaging

Two‐photon absorption and emission spectra for fluorophores relevant in cell imaging were measured using a 45 fs Ti:sapphire laser, a continuously tuneable optical parametric amplifier for the excitation range 580–1150 nm and an optical multichannel analyser. The measurements included DNA stains, fluorescent dyes coupled to antibodies as well as organelle trackers, e.g. Alexa and Bodipy dyes, Cy2, Cy3, DAPI, Hoechst 33342, propidium iodide, FITC and rhodamine. In accordance with the two‐photon excitation theory, the majority of the investigated fluorochromes did not reveal significant discrepancies between the two‐photon and the one‐photon emission spectra. However, a blue‐shift of the absorption maxima ranging from a few nanometres up to considerably differing courses of the spectrum was found for most fluorochromes. The potential of non‐linear laser scanning fluorescence microscopy is demonstrated here by visualizing multiple intracellular structures in living cells. Combined with 3D reconstruction techniques, this approach gives a deeper insight into the spatial relationships of subcellular organelles.     

Current variability in a wide and open lacustrine embayment in Lake Geneva (Switzerland)

Field measurements and numerical simulations were used to determine the effects of dominant meteorological conditions on the hydrodynamics of a wide (aspect ratio ~ 2), relatively deep (seasonally stratified) and open lake embayment (Vidy Bay, Lake Geneva). A three-dimensional hydrodynamic model (Delft3D-FLOW) was employed to simulate flow in the lake. High-resolution maps of wind, temperature and humidity (over the lake) were applied as input to drive the model. Because wind was the main force driving flow in the lake, currents in the embayment were investigated systematically for different wind conditions and seasonal stratification. Satisfactory model validation was achieved using drifter and moored measurements within the embayment. Markedly different circulation patterns were measured within the embayment, with the transition from one pattern to another occurring abruptly for small changes in wind direction. These distinct patterns resulted from relatively small changes in the large gyre of Lake Geneva's main basin, especially the angle between the current in front of the embayment and the embayment shoreline. The boundary between the embayment and the pelagic zone was defined by the largest gyre within the embayment. This study shows that, (i) in a large lake, complex current patterns can occur even within a minor embayment, and (ii) that these patterns can transition rapidly over a small range of wind directions. Near-shore gyre can occur for lengthy periods, which has implications for flushing of discharges within the embayment.