乳过氧化物酶对常见食品污染菌的抑制作用

分别采用分光光度法、菌体量法及孔扩散法研究了乳过氧化物酶（简写LP）对细菌和霉菌的抑菌活性及LP浓度、pH值和温度对抑菌活性的影响。结果表明：LP对于各供试菌均有很好的抑菌效果。其中，LP对铜绿假单胞菌、金黄色葡萄球菌和产黄青霉的抑制作用最显著，5μg／mL就能完全抑制他们的生长；在中性偏酸性环境中的抑菌活性比碱性环境的抑菌活性强；一定温度内处理不影响LP的抑菌活性；在中性条件下抑制供试革兰氏阴性菌和霉菌的能力强于Nisin。     

激光喷丸强化IN718高温合金抗热腐蚀机理

为了研究激光喷丸对IN718高温合金抗热腐蚀性能的影响,首先对IN718高温合金进行高功率激光喷丸强化处理,随后将试样置于800 ℃环境中进行热腐蚀试验,分别对比了喷丸样和未喷丸样残余压应力、微观组织、热腐蚀动力学曲线、腐蚀层的表面形貌和截面形貌等热腐蚀特性,最后阐述了激光喷丸强化IN718高温合金抗热腐蚀的机理.结果表明,激光喷丸样表层产生残余压应力且晶粒细化,喷丸样热腐蚀速率明显低于未喷丸样,喷丸样的腐蚀裂纹和腐蚀坑洞减少.分析认为晶粒细化加快了试样表面保护性氧化膜形成速度,减小了氧化膜内热应力和生长应力,残余压应力提高表层氧化膜的黏附性.同时,晶粒细化以及高温下晶界δ相的析出阻碍了硫、氧等元素的侵入,减缓内硫化氧化速度,从而提高了IN718高温合金的抗热腐蚀性能.     

Growth of pot roses and post-harvest rate of water loss as affected by air humidity and temperature variations during growth under continuous light

The effect of diurnal variations in air humidity and temperature under continuous lighting period (LP) on growth, flowering and water loss were studied in two pot-rose cultivars.     

山东省常见藜科植物叶蛋白研究及其营养价值评价

文章首次对山东省常见的10种藜科植物的叶蛋白产量及蛋白质含量进行了测定分析,并对其中提取率大于50%的三种植物的叶蛋白的氨基酸组成和含量进行了测定及营养价值评价,结果表明,藜料植物叶蛋白产量、蛋白质含量及提取率均较高,氨基酸组成齐全,含量丰富、平衡,其中藜和中亚滨藜具有较好的开发前景。由于藜科植物是典型的盐生植物,因此为开发利用山东省黄河三角洲盐渍化荒地及发展海水农业提供了理论依据。     

A spatial decision support system for long‐term forest management planning by means of linear programming and a geographical information system

The increased concern for environmental values increases the complexity of long‐term forest management planning. Environmental issues have to be dealt with over space and time. By creating links between existing aspatial long‐term forest management models and geographical information systems (GIS), environmental issues can be treated within the forest management planning process. In this article, a spatial decision support system (SDSS) developed by incorporating a forest management planning model into a GIS is presented. A case study is employed to illustrate the usefulness of the SDSS using real data. In order to preserve the water bodies in a forest area, the allowable treatments in areas falling within certain distances of lakes, streams, and swamps were restricted. Treatment schedules were simulated for all stands, and linear programming was utilized to maximize the net present value (NPV) subject to a non‐declining felling path. The NPV was reduced by 6.9% due to the treatment restrictions, and the annual harvest flow was reduced by about 10%. Various thematic maps of future time periods may be produced for subjective evaluation of the results.     

Optimization and Realization for Sinter and Ore Blending for Blast Furnace

In the ironmaking process, it is essential that sinter and feed of blast furnace are established economically and reasonably. Taking some steel company for example, the best economical condition for feed of blast furnace is comprehensively considered from technologic demand and economic efficiency. According to LP and based on practice and trial, aimed function and confined condition is confirmed, computation programs are made by Matlab while realizing optimization feed. The blast furnace material balance and heat balance are calculated by program with visual interface. Thus, we can directly judge rationality of optimization. The results show that LP is effective method to realize feed of blast furnace.     

Developing transgenic maize (Zea mays L.) with insect resistance and glyphosate tolerance by fusion gene transformation

Using linker peptide LP4/2A for multiple gene transformation is considered to be an effective method to stack or pyramid several traits in plants. Bacillus thuringiensis(Bt) cry gene and epsps(5-enolpyruvylshikimate-3-phosphate synthase) gene are two important genes for culturing pest-resistant and glyphosate-tolerant crops. We used linker peptide LP4/2A to connect the Bt cry1 Ah gene with the 2m G2-epsps gene and combined the wide-used man A gene as a selective marker to construct one coordinated expression vector called p2 EPUHLAGN. The expression vector was transferred into maize by Agrobacterium tumefaciens-mediated transformation, and 60 plants were obtained, 40% of which were positive transformants. Molecular detection demonstrated that the two genes in the fusion vector were expressed simultaneously and spliced correctly in translation processing; meanwhile bioassay detection proved the transgenic maize had preferable pest resistance and glyphosate tolerance. Therefore, linker peptide LP4/2A provided a simple and reliable strategy for producing gene stacking in maize and the result showed that the fusion gene transformation system of LP4/2A was feasible in monocot plants.     

Feed Formulation Using Linear Programming for Fry of Catfish,Milkfish, Tilapia,Asian Sea Bass,and Grouper in India

Nutritional profiles of 25 feed ingredients available in India were selected and compiled. Their costs were ascertained from Cochin (SW), Tuticorin (SE), and Bhubaneswar (NW), where fish/shrimp farming is traditionally practiced. Least-cost feed formulations (using the linprog toolbox in Matlab software) were attempted for catfish, milkfish, tilapia, and grouper fry specifying levels of four critical limits: Ca/P ratio, digestible energy (DE), 10 amino acid levels (where data was available), and 10 ingredients, totaling 26 constraining limits to the model. Feeds formulated for catfish fry cost US$0.066 kg^?1 at Bhubaneswar, US$0.117 kg^?1 at Tuticorin, and US$0.153 kg^?1 at Cochin, with poultry by-product meal and hydrolyzed feather meal as the major ingredients; limiting amino acids in these feeds were methionine and phenylalanine. Feeds formulated for milkfish fry cost US$0.110 kg^?1 at Cochin, US$0.108 kg^?1 at Tuticorin, and US$0.072 kg^?1 at Bhubaneswar; the limiting amino acids in this case were histidine and threonine. The cost of feeds for tilapia fry was US$0.207 kg^?1 at Cochin, US$0.369 kg^?1 at Tuticorin, and US$ 0.114 kg^?1 at Bhubaneswar; the limiting amino acid was methionine. Feed formulae for fry of Asian sea bass had an LP solution containing only five ingredients for all three places. The feed formula was the same for Cochin and Bhubaneswar market prices, and the total cost of ingredients was US$0.274 kg^?1 and US$0.142 kg^?1, respectively. At Tuticorin market prices, the feed formula cost was US$0.397 kg^?1. The feed formulae for grouper fry at Bhubaneswar and Tuticorin market prices had the same three ingredients costing US$0.114 kg^?1 and US$0.321 kg^?1, respectively, whereas feed formula for Cochin market price consisted of four ingredients costing US$0.280 kg^?1.     

A MATHEMATICAL PROGRAMMING MODEL OF YEAR-ROUND HYBRID STRIPED BASS (♀MORONE CHRYSOPS x ♂MORONE SAXATILIS) FINGERLING PRODUCTION

Year-round production of hybrid striped bass fingerlings has been limited by low survival in ponds during late summer. A whole-farm model was developed to assess economic effects of incorporating indoor tank production and mobile nursery systems to extend the fingerling production season. Mixed-integer linear programming models were constructed for six production scales with three sizes of ponds and indoor tanks and with a mobile fish nursery system. Optimal allocation of production activities was sensitive to varying survival rates of fingerlings and monthly sales patterns. Breakeven prices in winter production of hybrid striped bass fingerlings in indoor tanks were 3–4 times higher than in other months, implying that year-round production would require hybrid striped bass fingerling growers to receive higher prices to cover costs of production in winter months.     

Developing transgenic maize(Zea mays L.) with insect resistance and glyphosate tolerance by fusion gene transformation

Using linker peptide LP4/2A for multiple gene transformation is considered to be an effective method to stack or pyramid several traits in plants. Bacillus thuringiensis(Bt) cry gene and epsps(5-enolpyruvylshikimate-3-phosphate synthase) gene are two important genes for culturing pest-resistant and glyphosate-tolerant crops. We used linker peptide LP4/2A to connect the Bt cry1 Ah gene with the 2m G2-epsps gene and combined the wide-used man A gene as a selective marker to construct one coordinated expression vector called p2 EPUHLAGN. The expression vector was transferred into maize by Agrobacterium tumefaciens-mediated transformation, and 60 plants were obtained, 40% of which were positive transformants. Molecular detection demonstrated that the two genes in the fusion vector were expressed simultaneously and spliced correctly in translation processing; meanwhile bioassay detection proved the transgenic maize had preferable pest resistance and glyphosate tolerance. Therefore, linker peptide LP4/2A provided a simple and reliable strategy for producing gene stacking in maize and the result showed that the fusion gene transformation system of LP4/2A was feasible in monocot plants.