Effects of hygienic handling in combination with potassium sorbate treatment and smoking on the microbial quality and shelf-stability of croaker (Micropogonias furnieri)

 Fresh croaker (Micropogonias furnieri) were handled hygienically (i.e. in decontaminated containers) or conventionally (i.e. unhygienically) and dipped for 30 or 60s in 3% (w/v) potassium sorbate (KS) prior to hot-smoking. Changes in microbial, physical and sensory quality attributes during tropical ambient (28±2  °C) storage were investigated. Six bacterial genera of predominantly Enterobacteriaceae were isolated from the fresh samples subjected to hygienic treatment. A more heterogeneous bacterial flora of 11 genera was isolated from conventionally handled samples. Most of the Gram-negative bacteria were eliminated following smoking, resulting in the samples being dominated by Gram-positive bacterial flora consisting of Staphylococcus, Bacillus, Clostridium, Lactobacillus and Streptococcus. However, moulds (Aspergillus niger, Penicillium sp. and Rhizopus stolonifer) constituted the major spoilage organisms. Significant reductions (P=0.05) in total viable counts and coliform bacteria were observed in all samples after smoking. Further reductions occurred in samples held in decontaminated containers prior to smoking. Coliform bacteria were undetected on the 4th day in samples handled hygienically and dipped for 60 s in KS before smoking, but coliform growth and population increase occurred thereafter. The moisture content of the fresh samples was reduced significantly following smoking and tended to increase after about 8 days, but pH decreased slightly. Combination treatments of hygienic handling with extended dipping time (60 s) in KS and smoking exerted the maximum positive impact on the microbial quality and shelf-life of the samples. Received: 26 January 1998     

Local Photothermal Control of Phase Transitions for On-Demand Room-Temperature Rewritable Magnetic Patterning

The ability to make controlled patterns of magnetic structures within a nonmagnetic background is essential for several types of existing and proposed technologies. Such patterns provide the foundation of magnetic memory and logic devices, allow the creation of artificial spin-ice lattices, and enable the study of magnon propagation. Here, a novel approach for magnetic patterning that allows repeated creation and erasure of arbitrary shapes of thin-film ferromagnetic structures is reported. This strategy is enabled by epitaxial Fe_0.52Rh_0.48 thin films designed so that both ferromagnetic and antiferromagnetic phases are bistable at room temperature. Starting with the film in a uniform antiferromagnetic state, the ability to write arbitrary patterns of the ferromagnetic phase is demonstrated by local heating with a focused laser. If desired, the results can then be erased by cooling below room temperature and the material repeatedly re-patterned.     

Solid oxide fuel cell bi-layer anode with gadolinia-doped ceria for utilization of solid carbon fuel

Pyrolytic carbon was used as fuel in a solid oxide fuel cell (SOFC) with a yttria-stabilized zirconia (YSZ) electrolyte and a bi-layer anode composed of nickel oxide gadolinia-doped ceria (NiO-GDC) and NiO-YSZ. The common problems of bulk shrinkage and emergent porosity in the YSZ layer adjacent to the GDC/YSZ interface were avoided by using an interlayer of porous NiO-YSZ as a buffer anode layer between the electrolyte and the NiO-GDC primary anode. Cells were fabricated from commercially available component powders so that unconventional production methods suggested in the literature were avoided, that is, the necessity of glycine-nitrate combustion synthesis, specialty multicomponent oxide powders, sputtering, or chemical vapor deposition. The easily-fabricated cell was successfully utilized with hydrogen and propane fuels as well as carbon deposited on the anode during the cyclic operation with the propane. A cell of similar construction could be used in the exhaust stream of a diesel engine to capture and utilize soot for secondary power generation and decreased particulate pollution without the need for filter regeneration.     

Influence of carbonisation on selected engineering properties of carbon resin electrodes for electrochemical treatment of wastewater

In this study, effects of selected factors on selected properties of carbon resin electrodes (CRE) have been investigated. CRE were developed from used dry cells and resin using non‐heat‐treatment process. Selected properties (density, electrical resistance, microstructure, hygroscopy, stability moisture content, compressive and flexural strength) of the electrodes were monitored and effects of carbonisation temperature, carbon particle size, and compaction pressure on these properties were studied. The study revealed that the density of CRE was in the range of 1.33 to 1.59 g/cm³, compressive strength ranged from 36.56 to 43.81 MN/m², flexural strength, moisture content, and swelling were in the range of 6.76 to 8.10 MN/m², 0.84–0.93%, and 6.04–9.30%, respectively. In all cases electrical resistance and density of CRE decreased with increasing carbonisation temperature at various operational factors (particle size, compacting pressure, and percentage of the resin used). Also, it was revealed that carbonisation of CRE from 30 to 220°C reduced specific electrical resistance and density from 1.85 to 1.29 × 10^?1 Ω/cm and from 1.35 to 1.24 g/cm³, respectively, but carbonisation temperature had no significant effect on wetness, compressive and flexural strength, stability, and moisture content of the electrodes. Estimated costs revealed that cost of producing CRE was cheaper ($13.25/m) than that of heat‐treated electrodes ($33.33/m). It was concluded that carbonisation temperature, particle size, compacting pressure, and percentage of the resin used are important factors in the development of CRE with lower specific electrical resistance.     

回流污泥预浓缩强化新型氧化沟系统生物除磷的研究(英文)

A pilot-scale,pre-anoxic-anaerobic oxidation ditch was used in this study to treat municipal wastewater with limited carbon source.A novel return activated sludge(RAS) pre-concentration tank was adopted for improv-ing the phosphorus removal efficiency and the effects of RAS pre-concentration ratio were studied.Under the opti-mal operational condition,the suspended total phosphorus(STP) and the total phosphorus(TP) removal efficiencies were around 58.9% and 63.9% respectively and the effluent-P was lower than 0.8 mg·L-1.The reason is that with the optimal RAS pre-concentration ratio,nitrate is completely removed with endogenous carbon source and the secondary phosphorus release is strictly restrained in the pre-anoxic tank.Therefore,the anaerobic phosphorus release and the carbon source uptake by phosphorus accumulation organisms(PAOs) in the sludge,which are ex-tremely important to the phosphorus removal process,can be fully satisfied.Furthermore,the oxidation-reduction potential is proved to be suitable for controlling the RAS pre-concentration ratio due to influent fluctuation and varied conditions.The novel modified system is also beneficial for PAO accumulation.     

Effectiveness of anode in a solid oxide fuel cell with hydrogen/oxygen mixed gases

A porous Ni/YSZ cermet in mixed hydrogen and oxygen was investigated for its ability to decrease oxygen activity as the anode of a single chamber SOFC. A cell with a dense 300 μm YSZ electrolyte was operated in a double chamber configuration. The Ni–YSZ anode was exposed to a mixture of hydrogen and oxygen of varying compositions while the cathode was exposed to oxygen. Double chamber tests with mixed gas on the anode revealed voltage oscillations linked to lowered power generation and increased resistance. Resistance measurements of the anode during operation revealed a Ni/NiO redox cycle causing the voltage oscillations. The results of these tests, and future tests of similar format, could be useful in the development of single chamber SOFC using hydrogen as fuel.     

Synthesis, Analysis, and Field Activity of Sordidin, a Male-Produced Aggregation Pheromone of the Banana Weevil, Cosmopolites sordidus

An efficient synthesis of the diastereoisomers of sordidin (1), a male-produced aggregation pheromone of Cosmopolites sordidus, has been developed from commercially available 4-methylpent-4-en-2-ol (2). Preparation of exo-β-sordidin (1a) and endo-β-sordidin (1b) is via the anti epoxide, 4d, which is derived via iodocarbonation of 2. The endo-α-sordidin (1c) and exo-α-sordidin (1d) are prepared from the corresponding syn epoxide, which is available via stereo-controlled epoxidation of the triisopropylsilyloxy derivative, 3b. Silyloxy derivatives of the epoxides, 4, efficiently alkylate the anions of N-cyclohexyldiethylketimine (6a) and 3-pentanone N,N-dimethylhydrazone (6b). Acidic work-up of these alkylation reactions promotes cyclization to give 1. Gram quantities of 1a?1d, 1a + 1b and 1c + 1d have been prepared by this route. In field tests in a banana plantation in Costa Rica, compounds 1a?1d significantly increased capture rates of standard pseudostem traps. Comparable numbers of adults were attracted to pseudostem traps baited with the major naturally occurring isomers of sordidin 1c + 1d or 1a?1d. Although addition of the minor naturally occurring isomers of sordidin (1a and 1b) to pseudostem traps increased capture rates above controls, these compounds did not increase attraction of pseudostem traps to the same extent as 1a?1d. In comparison tests with conventional pseudostem traps, significantly more adults were trapped in water-containing pitfall traps baited with 1a?1d.     

16th International Drying Symposium (IDS2008)

This study introduces sensor psychrometrics, as opposed to the physically constrained static gravimetric experimentation, for the characterisation of cobed maize drying. Simultaneous spreadsheet integration and Solver analytics were used to interpret the digital drying curve from sensor-sampled psychrometric data. The results were validated gravimetrically at dryer settings of 37, 43, and 53°C. The ear drying curves were reproduced with a goodness-of-fit consistency of 0.997–0.999 across the different calibration settings. The new methodology, presented along with its uncertainty, exploits advances in computing and instrumentation to digitize empirical drying, moving experimentation beyond the rigid confines of the lab to the desktop.