Cultivating the marine microalga Nannochloropsis salina under various nitrogen sources: Effect on biovolume yields,lipid content and composition,and invasive organisms

Algae can be a viable source for biofuel production, but the source of nitrogen used to cultivate could affect algae yields. Here, we observe how various nitrogen treatments can impact the growth and biovolume of microalga Nannochloropsis salina as well as invasion of undesired organisms. Invading organisms increase the likelihood of crashes of the desired microalgae culture. Experiments were conducted over 28 days in open aquaria in a greenhouse. We used five different nitrogen treatments; ammonium chloride (NH₄Cl), ammonium hydroxide (NH₄OH), sodium nitrate (NaNO₃), urea (CH₄N₂O), and a mixture of all these sources. Highest values for Maximum Sustainable Yield (MSY), a measure of potential harvest rate based on population productivity, were observed in the urea treatment, but cell size was smaller compared to other treatments. Sodium nitrate and the mixture of nitrogen sources also had high MSY values but larger cell sizes, making them the treatments with highest total biovolume. The highest percentages of lipid by weight, but also highest densities of invading organisms were observed in the mixed treatment. Our results suggest that tradeoffs between biovolume and lipid yields as well as culture success can ultimately decide what nitrogen sources to use.     

富铁面包酵母的筛选及富集条件研究

本文探索获得富铁面包酵母的富集条件。筛选获得一株富铁能力较强的面包酵母菌株QN006。通过单因素实验确定该菌株富铁工艺条件为:铁盐种类为硫酸亚铁,亚铁离子浓度为900μg/mL,添加时间为0h,温度为28℃,pH为5.0。在此条件测得面包酵母QN006的铁富集量为13.92mg/g干菌体,不加糖面团发酵力达到623mL/h。     

海月构造带东三段滩坝砂分布及成藏主控因素分析

辽河滩海地区海月构造带东三段沉积期,三角洲前缘砂体受湖岸流和波浪的改造,形成了一系列滩坝砂沉积,细分为滩砂和坝砂,水动力强则形成坝砂,水动力弱则形成滩砂;滩坝砂平行于湖岸线呈带状分布,易于形成岩性圈闭。滩坝砂受砂体发育规模、储层物性、断裂输导体系及封堵性等多种因素控制,在滩坝砂较为发育的东三下段,靠近海南断层、盖州滩断层且封堵条件优越的滩坝砂最易于成藏。     

合金钢连铸机铸坯划痕缺陷的治理

针对六机六流合金钢连铸机频繁出现铸坯表面划痕、凹陷等缺陷采取一系列改造措施，改造后彻底消除了铸坯划痕、凹陷等表面质量缺陷。     

A methodology for applying students' interactive task performance scores from a multimedia-based performance assessment in a Bayesian Network

Computer-based simulations are increasingly being used in educational assessment. In most cases, the simulation-based assessment (SBA) is used for formative assessment, which can be defined as assessment for learning, but as research on the topic continues to grow, possibilities for summative assessment, which can be defined as assessment of learning, are also emerging. The current study contributes to research on the latter category of assessment. In this article, we present a methodology for scoring the interactive and complex behavior of students in a specific type of SBA, namely, a Multimedia-based Performance Assessment (MBPA), which is used for a summative assessment purpose. The MBPA is used to assess the knowledge, skills, and abilities of confined space guard (CSG) students. A CSG supervises operations that are carried out in a confined space (e.g., a tank or silo). We address two specific challenges in this article: the evidence identification challenge (i.e., scoring interactive task performance), and the evidence accumulation challenge (i.e., accumulating scores in a psychometric model). Using expert ratings on the essence and difficulty of actions in the MBPA, we answer the first challenge by demonstrating that interactive task performance in MBPA can be scored. Furthermore, we answer the second challenge by recoding the expert ratings in conditional probability tables that can be used in a Bayesian Network (a psychometric model for reasoning under uncertainty and complexity). Finally, we validate and illustrate the presented methodology through the analysis of the response data of 57 confined space guard students who performed in the MBPA.