新型双输入Boost变换器

针对传统的多输入变换器(MIC)具有电路结构复杂、电压增益低或开关器件电压应力高的问题,提出了一种新型双输入Boost变换器拓扑结构.该拓扑由2个完全一致的基本Boost变换器子拓扑构成,每个基本Boost变换器的功率开关管分别并联一个功率二极管,在单输入状态时一个始终导通.另一个始终关断;在双输入状态时,2个功率二极管全部关断.分析了2种输入状态下的工作原理及各个阶段的工作模态,结果表明该变换器适合工作在双输入状态,且在此状态时可以实现2种不同性质的电源输入,具有电压增益高、开关器件电压应力低等优点.研制了一台输出功率为240 W的双输入Boost变换器原理样机,通过实验验证了理论分析的正确性.     

High-efficiency grid-connected photovoltaic module integrated converter system with high-speed communication interfaces for small-scale distribution power generation

This paper presents a high-efficiency grid-connected photovoltaic (PV) module integrated converter (MIC) system with reduced PV current variation. The proposed PV MIC system consists of a high-efficiency step-up DC-DC converter and a single-phase full-bridge DC-AC inverter. An active-clamping flyback converter with a voltage-doubler rectifier is proposed for the step-up DC-DC converter. The proposed step-up DC-DC converter reduces the switching losses by eliminating the reverse-recovery current of the output rectifying diodes. To reduce the PV current variation introduced by the grid-connected inverter, a PV current variation reduction method is also suggested. The suggested PV current variation reduction method reduces the PV current variation without any additional components. Moreover, for centralized power control of distributed PV MIC systems, a PV power control scheme with both a central control level and a local control level is presented. The central PV power control level controls the whole power production by sending out reference power signals to each individual PV MIC system. The proposed step-up DC-DC converter achieves a high-efficiency of 97.5% at 260 W output power to generate the DC-link voltage of 350 V from the PV voltage of 36.1 V. The PV MIC system including the DC-DC converter and the DC-AC inverter achieves a high-efficiency of 95% with the PV current ripple less than 3% variation of the rated PV current.     

一种改进的快速角点检测方法研究

传统的Harris角点检测算法检测率和可重复率高,但无法满足实时性要求,而Trajkovic等提出的角点检测器虽然计算量小,但是易对边缘产生伪响应,针对这些问题,提出一种新的基于Harris的快速角点检测算法。该算法使用多格算法,并使用四个基础方向上最小强度变化作为预处理结果,再使用自相关矩阵得到角点的响应函数。实验结果表明,新算法改进了Harris 算法和MIC算法,能够有效地抑制边缘响应及纹理角点,并且能够满足实时性要求。     

逼真生成表格式数据的非时间属性关联模型

针对数据仿真过程中表格数据属性间关联难的问题,提出一种刻画表格数据中非时间属性间关联特征的H模型。首先,从数据集中提取评价主体和被评价主体关键属性,进行两重频数统计,得到关于关键属性的4个关系对;然后,计算各关系对的最大信息系数（MIC）来评估各关系对的相关性,并采用拉伸指数分布（SE）对各关系对进行关系拟合;最后,设置评价主体和被评价主体的数据规模,根据拟合出的关系计算出评价主体的活跃度和被评价主体的流行度,通过活跃度总和等于流行度总和建立关联,得到非时间属性关联的H模型。实验结果表明,利用H模型能有效地刻画真实数据集中非时间属性间的关联特征。     

橙皮苷及铜配合物的抑菌抗氧化活性研究

橙皮苷-Cu(Ⅱ)配合物属于新的物质,用牛津杯法研究了橙皮苷及其配合物对大肠杆菌、枯草芽孢杆菌、金黄色葡萄球菌的抑菌活性,橙皮苷-Cu(Ⅱ)配合物对3种菌的最低抑菌浓度,以及不用pH值对配合物抑菌效果的影响。另外,还研究了橙皮苷及其配合物对.OH的清除效应。结果发现橙皮苷-Cu(Ⅱ)配合物的抑菌活性强于橙皮苷,而对.OH的清除作用则不如橙皮苷。     

Chemistry and medicinal properties of the Bakul (Mimusops elengi Linn): A review

India is one of the world's biodiversity hotspots and reports confirm that a great variety of fruiting trees are indigenous to this region of the world. Mimusops elengi Linn (family Sapotaceae) commonly known as Bakul is one such tree native to the Western Ghat region of the peninsular India. However, today this tree is also found growing in other parts of the tropical and subtropical regions of the world. The tree is of religious importance to the Hindus and finds mention in various mythological texts. The stem, barks, leaves and fruits are used in various Ayurvedic and folk medications to treat various ailments. In the prehistoric days the ripe fruits were an important source of diet but today no one knows of its dietary use as it is seldom used. Studies suggest the tree contains medicinally-important chemicals, particularly the triterpenes and alkaloids. Preclinical studies in the past five years have shown that the extracts prepared from Bakul possess antibacterial, antifungal, anticariogenic, free radical scavenging, antihyperglycemic, antineoplastic, gastroprotective, antinociceptive and diuretic effects, thus lending pharmacological support to the tree's ethnomedicinal uses in Ayurveda. In this review for the first time attempt is made at addressing the chemical constituents, medicinal uses and validated pharmacological observations of Bakul.     

醋蒜提取物抑菌作用研究

对醋蒜的乙醇提取物(PGEE)、水提物(PGWE)、醋蒜浸泡液(PPG)的抑菌活性进行了研究，测定了各提取物的MIC和MBC，同时对各提取物的耐热性进行了分析，并以鲜大蒜的相应提取物作为对照。结果表明PGEE、PGWE和PGJ的MIC分别为0．313～0．625mg／mL，5～10mg／mL，1．25～2．5mg／mL；鲜大蒜的醇提物(GEE)和水提物(GWE)的MIC分别为0．156～0．313mg／mL和0．625～1．25mg／mL。醋蒜醇提物和浸泡液的抑菌活性较好，且它们抑菌作用的热稳定性优于鲜蒜提取物。     

Evaluation of the antimicrobial activity of aqueous extracts from dry Vaccinium corymbosum extracts upon food microorganism

As blueberries are rich in phenolic compounds, which possess a demonstrated antimicrobial activity, it may be interesting to further elucidate its real potential and properties. As such, the main goal of this work was to evaluate the potential antimicrobial activity of Vaccinium corymbosum dry fruits and leaves aqueous extracts against several contaminants/pathogenic microorganisms while at the same time assessing the effect of V. corymbosum over lactic acid bacteria.     

解淀粉芽孢杆菌HRH317菌株抗菌肽发酵条件优化及其抑菌活性研究

本文以抑菌圈直径为指标,采用单因素试验和响应面法对解淀粉芽孢杆菌HRH317菌株产抗菌肽的发酵条件进行优化,并对该抗菌肽的抑菌谱及其最小抑菌浓度(MIC)进行了研究。得到最佳发酵条件为：pH7.5,装液量为50 mL,接种量3%,培养时间13h、温度38.5℃、转速145r/min,抗菌肽含量441.56±1.24 μg/mL。在此条件下抗菌肽的抑菌圈直径达15.95 mm。针对9种指示菌的抑菌谱结果表明,抗菌肽对枯草芽孢杆菌、金黄色葡萄球菌抑制效果最好,其次是霉菌、酵母菌。其中,抗菌肽对枯草芽孢杆菌、金黄色葡萄球菌的MIC为 3.45 μg/mL,大肠杆菌、白地霉、巴氏醋酸杆菌MIC为6.9 μg/mL,禾谷镰孢菌、黄曲霉、假丝酵母MIC为 55.20 μg/mL,红酵母MIC为110.40μg/mL。     

Biological activities of Solanum paludosum Moric. extracts obtained by maceration and supercritical fluid extraction

Solanum paludosum extracts obtained by maceration (SP-EtOH_CRUDE and SP-EtOH_MARC) and supercritical fluid extraction (SP-SFECO₂) were evaluated. Three extracts with distinct chromatographic profiles were obtained: SP-EtOH_CRUDE, with a complex phenolic composition; SP-SFECO₂, containing methoxylated flavonoids; and SP-EtOH_MARC, which bears mainly polar polyphenols. All extracts were strong antioxidants, as measured using the diphenylpicrylhydrazyl (DPPH) method, xanthine/xanthine oxidase/luminol and iron-induced lipid peroxidation systems. Extracts were also evaluated as modifiers of antibiotic activity in strains of Staphylococcus aureus expressing fluoroquinolone, macrolide and tetracycline efflux proteins. Despite their lack of antibacterial activity, all extracts were able to potentiate antibiotics activities by as much as eight fold. Both the maceration and supercritical fluid extraction processes were adequate to obtain extracts with different biological activities according to their patterns of phenolic compounds. The data suggest that S. paludosum could be a valuable source of antioxidants and putative efflux pumps inhibitors.