广东某复杂铜铅锌矿浮选试验研究

广东某复杂铜铅锌矿石中的矿物嵌布粒度较细且相互包裹，导致现场铜、铅、锌浮选分离困难，为解决此问题进行了选矿试验研究。结果表明：在选铜时，选用FK 1与DS组合抑制铅锌，可有效解决精矿的互含问题；在高碱工艺下，采用先铜后锌的优先浮选工艺，铜铅粗泡再磨后经2次精选，能获得铜品位为2110%、回收率为8088%的铜精矿，铅锌总含量为1023%，达到铜精矿四级品要求；采用1粗2精2扫流程处理选铜尾矿，获得了锌品位为5217%、回收率为9278%的锌精矿。试验所用药剂全部为常规药剂，试验流程结构简单，现场实施比较容易，可作为现场改造的依据。     

A problem solving oriented intelligent tutoring system to improve students' acquisition of basic computer skills

Personalization and intelligent tutor are two key factors in the research on learning environment. Intelligent tutoring system (ITS), which can imitate the human teachers' actions to implement one-to-one personalized teaching to some extent, is an effective tool for training the ability of problem solving. This research firstly discusses the concepts and methods of designing problem solving oriented ITS, and then develops the current iTutor based on the extended model of ITS. At last, the research adopts a quasi-experimental design to investigate the effectiveness of iTutor in skills acquisition. The results indicate that students in iTutor group experience better learning effectiveness than those in the control group. iTutor is found to be effective in improving the learning effectiveness of students with low-level prior knowledge.     

LaCoO3 acts as a high-efficiency co-catalyst for enhancing visible-light-driven tetracycline degradation of BiOI

Exploring noble-metal-free co-catalysts highly flexible for separating the photogenerated charge carriers is of prime importance for the visible-light-driven photocatalysis. Herein, three-dimensional flower-like BiOI microspheres were fabricated and applied to support noble-metal-free LaCoO₃ co-catalysts to construct a unique LaCoO₃/BiOI hybrid photocatalyst with a higher ability in charge separation. As expected, the optimum tetracycline degradation rate of LaCoO₃ (4.0 wt%)/BiOI was up to 0.0161 min⁻¹, which was nearly 3.4 fold larger than that of pure BiOI (0.0048 min⁻¹). The enhanced photocatalytic performance was mainly ascribed to the vital role of LaCoO₃ co-catalyst, which acted as an excellent electron collector for capturing the electrons generated by BiOI, effectively promoting the separation of photogenerated charge carriers and prolonging the lifetime of photo-induced electron-hole pairs at the same time. Furthermore, the active species trapping experiments revealed that the excellent photocatalytic activity was primarily driven by photogenerated holes and superoxide radicals. This work is expected to provide a new inspiration for rationally designing and fabricating noble-metal-free co-catalyst system with high efficiency applied in environment purification.     

复合蛋白酶水解黑豆粕制备多肽的工艺优化

为充分利用黑豆粕中的蛋白质资源,研究了复合蛋白酶水解黑豆粕制备多肽的工艺路线。从蛋白酶的筛选入手,考察了不同蛋白酶对黑豆粕水解效果的差异,并通过复配比例优化了最佳复合蛋白酶的组成。采用单因素试验及响应面试验确定了复合蛋白酶水解黑豆粕的最佳工艺条件。结果表明:最佳复合蛋白酶为胰蛋白酶、碱性蛋白酶与桔青霉蛋白酶按酶活比1∶3∶2复配;最佳工艺条件为加酶量5 670 U/g,底物蛋白质量浓度40 g/L,pH 9.55,水解温度50℃,水解时间6 h。在优化的工艺条件下水解黑豆粕,多肽得率可以达到82.44%。水解液中多肽的相对分子质量均在7.8 kDa以下,大部分多肽的相对分子质量小于3.3 kDa;多肽基本上保持了黑豆粕蛋白的氨基酸组成,具有较高的营养价值。     

VN基硬质耐磨涂层的制备及其性能

目的在N2及其与C2H2混合气氛下,制备VN基硬质耐磨涂层,研究VN基涂层的结构及力学、耐磨、抗腐蚀性能,为工业化应用积累科学数据。方法采用阳极层离子源辅助阴极电弧离子镀系统,在高速钢衬底上制备VN、VCN和VCN/VN多层涂层,系统研究多层涂层调制周期厚度变化对涂层晶体结构、表面形貌、硬度、耐磨性及耐腐蚀性能的影响。结果 C原子的加入和VCN/VN多层涂层调制周期的变化对VCN/VN涂层的晶体结构、表面形貌、硬度、摩擦系数及耐腐蚀性能均有明显影响。随着VCN/VN涂层调制周期的增加,VN(200)衍射峰逐渐减弱并宽化,VN (111)衍射峰消失,涂层表面金属熔滴大颗粒数量减少,小颗粒数量明显增加。VN涂层硬度为1890HV,VCN涂层硬度为2290HV,VN/VCN多层涂层硬度为2350HV左右。对磨材料为氧化铝时,VN涂层的摩擦系数为0.74左右,VCN涂层和VCN/VN涂层的摩擦系数明显降低,在0.60左右,磨损机理由以磨削磨损为主(VN涂层)逐渐转化为粘着磨损为主(S5),磨削磨损起次要作用。随着C原子的加入和VCN/VN多层涂层调制周期的变化,涂层耐腐蚀性能明显增强,自腐蚀电位由VN的-0.26 V增大到VCN的-0.14 V,自腐蚀电流密度由1.63′10^-5 A/cm^2降低到2.7′10(-6) A/cm^2。结论采用阳极层离子源辅助电弧离子镀技术可制备VN基硬质耐磨涂层,C元素的加入可有效提高VN涂层的硬度,降低VN涂层的摩擦系数,增强VN涂层的耐腐蚀性能。VCN/VN多层涂层通过周期厚度的调制可以有效提高VN基涂层的硬度、耐磨及耐腐蚀性能。     

“新工科”背景下线上线下一体化教学模式探讨——以《试验设计与数据处理》课程为例

为了更好的为食品专业应用型"新工科"人才培养服务,针对《试验设计与数据处理》传统课堂教学存在的问题,对课程从教学内容、教学方法和考核方法三个方面进行改革。通过线上线下一体化,课内、课外同步学,理论与实操并重的方式,有效激发了学生的课程学习积极性,提升了课程成绩和学生对课程知识的理解能力和运用能力。     

SnS2 -SnO2 / 石墨烯复合材料的合成及其电化学储锂性能的研究

目的制备高容量和循环性能稳定的锂离子电池复合电极材料。方法通过L-半胱氨酸(Lcys)辅助水热法合成SnS2-SnO2/石墨烯复合纳米材料,采用XRD,SEM,TEM和HRTEM技术对其进行结构表征,并采用循环伏安、恒流充放电和电化学阻抗技术研究了其电化学贮锂性能。结果随着水热溶液中L-cys的量增加,复合材料中少层数结构SnS2的含量也增加。当Sn4+/L-cys的物质的量之比为1∶4时,制得了SnS2/石墨烯复合纳米材料,而且石墨烯的存在在一定程度上抑制了SnS2沿c轴方向的生长,减少了层状SnS2的层数。结论由于二维层状结构的SnS2具有与石墨烯类似的微观结构和形貌,与石墨烯的复合具有更好的匹配性和相互协同效应,增强了SnS2/石墨烯复合材料的电化学贮锂性能,使其具有较高的可逆储锂容量、良好的循环性能和增强的倍率特性。     

Lactococcus lactis phages from the perspective of their diversity,thermal and biocidal resistance

Lactic acid bacteria (LAB), particularly Lactococcus lactis, are of great significance in dairy fermentations. Many LAB strains are susceptible to attack by phages that affect their technological, biochemical and physiological functions. Phages of L. lactis are a serious concern because of the economic importance of this bacterium in the dairy industry. Members of L. lactis phages belonging to the P335, 936 and c2 groups are more problematic for the dairy industry. Many phages of the 936 group are resistant to various thermal and biocidal treatments commonly used in the dairy industry. This article reviews the diversity of L. lactis bacteriophages of the P335, 936 and c2 groups and discusses their interaction with their bacterial hosts. In addition, this review provides an overview of the resistance of L. lactis phages to thermal treatments and chemical biocides, and highlights some novel strategies to destroy these phages.