Thermal matching performance of a geothermal ORC system using zeotropic working fluids

The thermal matching performance analysis is conducted for a geothermal organic Rankine cycle system using zeotropic mixtures as working fluids. The constant isentropic efficiency is replaced by internal efficiency of an axial flow turbine with given size for each condition, and the zeotropic mixtures of isobutane and isopentane is used as working fluids of the organic Rankine cycle, in order to improve thermal match in evaporator and condenser. The results showed the use of zeotropic mixtures leads to the prominent thermodynamic first law and second law efficiencies, especially at high minimum temperature difference in evaporator (Δt₁), and there exists an optimal thermal performance at some certain mole fraction of isopentane in zeotropic mixtures (x) and Δt₁. The geothermal organic Rankine cycle with x of 0.2 and Δt₁ of 16 K shows the maximal thermodynamic first law and second law efficiency in this research. The geothermal organic Rankine cycle system using zeotropic mixtures shows the optimal overall thermal performance at some certain x, which is not necessary to be the point with the maximal temperature glide. The use of zeotropic mixtures is not always lead to a high thermal to electricity efficiency compared to the pure working fluid, and its overall net power output of P_ORC is even lower than the pure working fluids compositions at some certain x.     

Detecting and measuring rings in banknote images

Various intelligent systems show a rapidly growing potential use of visual information processing technologies. This paper presents an example of employing visual information processing technologies for detecting and measuring rings in banknote images. The size of the rings is one of parameters used to inspect the banknote printing quality. The approach developed consists of two phases. In the first phase, based on histogram processing and data clustering, image areas containing rings are localized and edges of the rings are detected. Then, in the second phase, applying the hard and possibilistic spherical shell clustering to the extracted edge pixels the ring centre and radii are estimated. The experimental investigations performed have shown that even highly occluded rings are robustly detected. Several prototypes of the system developed have been installed in two banknote printing shops in Europe.     

萃取精馏分离丙醇-水-乙酸丙酯混合物

为挑选萃取精馏分离丙醇-水-乙酸丙酯混合物较好的溶剂,采用基于UNIFAC模型的动态法对待选溶剂进行了计算机高通量筛选。根据加入溶剂后体系互溶性和相对挥发度大小的预测结果,经综合考虑选出较好的萃取剂为丁醇和甲醇。选取丁醇为溶剂做实验验证,测定了丙醇-水-乙酸丙酯-丁醇体系的部分汽液平衡实验数据;泡点温度tb、加入溶剂后的相对挥发度α和平衡气相组成yi的计算值与实验值吻合良好,这表明采用基于UNIFAC模型的动态法筛选萃取精馏的溶剂具有良好的可靠性和适用性。     

Use of gamma irradiation for inactivation of pathogens inoculated into Kimbab,steamed rice rolled by dried laver

The effect of gamma irradiation for inactivating the pathogens inoculated into the ready-to-eat Kimbab, steamed rice rolled by dried laver, was investigated. The pathogens used were Salmonella Typhimurium, Escherichia coli, Staphylococcus aureus and Listeria ivanovii which are important for public health. The growth of four test organisms inoculated (about 10⁶–10⁷ CFU/g) into the Kimbab were sustained by an irradiation treatment during 24 h of storage regardless of the temperature at 10, 20 and 30 °C. Four pathogen inoculated into Kimbab decreased 2–3 log CFU/g by 1 kGy treatment and was not detected after 3 kGy. The D₁₀ value of pathogens inoculated into the Kimbab were 0.31–0.44 kGy among the four organisms. This study indicated that a low dose irradiation can maintain microbial safety for ready-to-eat Kimbab, steamed rice rolled by dried laver.     

Effect of medium temperature setting on gelling characteristics of surimi from some tropical fish

Effects of setting at 25 °C on textural properties and cross-linking of myofibrillar proteins in surimi produced from threadfin bream (Nemipterus bleekeri), bigeye snapper (Priacanthus tayenus), barracuda (Sphyraena jello) and bigeye croaker (Pennahai macrophthalmus) were investigated. Increase in setting time (0–8 h) resulted in a higher breaking force and deformation for all surimi gels tested (P<0.05). Increased gel strength was associated with increase in non-disulfide bond formation and decreased heavy chain myosin. Proteins underwent degradation during setting; however polymerization occurred to a much higher extent, leading to a strengthened gel matrix. Therefore, setting at 25 °C, for an appropriate time, should be a promising means to improve gelling properties of surimi produced from tropical fish.     

粉煤灰沸石处理含铅废水的研究

在对含铅废水处理方法进行分析的基础上,对粉煤灰沸石处理含铅废水进行了实验研究,对处理工艺进行了探讨,得到了最佳工艺参数.实验结果表明,粉煤灰沸石是一种优良的含铅废水处理剂,在水处理领域将有广阔的应用前景.     

Technological properties of Lactobacillus plantarum strains isolated from Chinese traditional low salt fermented whole fish

A total of 21 Lactobacillus plantarum were isolated from a Chinese traditional low salt fermented whole fish product “Suan yu” and identified by biochemical and molecular methods. The isolates were screened for acidifying and amino-biogenic ability for proteolysis, lipolysis, antimicrobial activity, and sensory in order to select the most suitable candidates as the starter cultures. All the strains had high acidifying activities and were able to reduce the pH to lower than 4.5 in 36, 24 and 16 h at 15, 25 and 37 °C respectively. Major strains showed antimicrobial activities against Listeria monocytogenes, Staphylococcus aureus and Escherichia coli, and ten L. plantarum strains could produce bacteriocins. Five L. plantarum strains exhibited weak proteolytic activities against myofibrillar proteins, as evidenced by the agar plate assay and sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE). None of the strains showed lipolytic activity. Major L. plantarum strains displayed different enzymatic profiles. Besides, the isolates mostly showed negative-decarboxylase activities, but Lp-10 had a decarboxylase activity against l-tyrosine. Furthermore, the fermented fish surimi inoculated with Lp-15 and Lp-21 strains respectively scored high for overall acceptability. Therefore, Lp-15 and Lp-21 presented the best technological properties, which should be given first priority as the starter culture for manufacturing fermented fish products.     

High peroxidase catalytic activity of exfoliated few-layer graphene

Few-layer graphene prepared from graphite exfoliated by chitosan has a preserved structure without oxidation or destruction of the sp² character of the carbon plane and exhibits a higher peroxidase catalytic activity than that of graphene oxide (GO) and its reduced form. The peroxidase catalytic activity of as-obtained few-layer graphene is 45 times higher than that of GO and 4 times higher than that of reduced GO with the same concentration of 30 μg mL⁻¹ and the detection limit of hydrogen peroxide is 10 nM. The excellently catalytic performance can be attributed to the fast electron transfer on the surface of few-layer graphene, which is further confirmed by electrochemical characterization. The as-prepared few-layer graphene has been used to determine hydrogen peroxide in three real water samples with satisfactory results.     

动态法筛选萃取精馏分离乙酸丁酯-丁醇-水共沸物的溶剂

采用基于改进UNIFAC模型的动态法对萃取精馏法分离乙酸丁酯-丁醇-水共沸物的萃取剂进行了计算机高通量筛选,根据适宜萃取剂选取原则和计算结果,经综合考虑选出较好的萃取剂为甲醇、乙醇、环氧乙烷。选取乙醇进行实验验证,测定了乙酸丁酯-丁醇-水-乙醇体系的部分汽液平衡实验数据;泡点温度tb、加入溶剂后平衡汽相组成的计算值与实验值吻合良好;以乙醇作为萃取剂具有热负荷小、毒性低和热稳定性好的优点。结果表明,采用基于改进UNIFAC模型的动态法筛选萃取精馏法的溶剂具有良好的可靠性和适用性,可以极大地节省人力、物力和财力。     

连云港海域螺类软体部分重金属和微量元素分析

分析评价连云港海产螺类可食部分微量元素及重金属含量的安全性。用硝酸-高氯酸消化法消解组织,用电感耦合等离子体原子发射光谱法测定元素含量。结果显示:9种螺类及同种螺不同组织中Pb、Cd、Sn、As、Mn、Fe、Ni、Ag、Se、Cr、Co、Zn和Cu 13种元素含量存在差异。被测试螺中含有Fe、Cu、Zn、Co、Mn、Cr、Se和Sn等人体必需微量元素;重金属元素As、Cd和Pb的残留量指数(I)较高,且在不同螺的不同组织中的含量存在显著差异。As在9种螺类中均超标。管角螺足肌As、内脏团Cd的含量最高;Pb在托氏虫昌螺1(I=6.5)和2(I=5.5)、扁玉螺足肌(I=2.1)和管角螺内脏团(I=1.22)含量超标,其余样品低于国家食品卫生标准或I值小于1。除扁玉螺足肌组织外(I=1.21),扁玉螺内脏团和其余8种螺Cr的I值均小于1。