判断某点是否在任意多边形内两种算法的比较

多边形是计算机图形学中一个重要的概念,尤其是在GIS中,判断某点是否落在指定多边形内的算法很重要。据此,对目前普遍采用的两种判断方法,即射线法和角度累加法进行了详细的比较,并对两种算法在CAD软件下的程序实现提供了具体方案。     

分层开采的切顶房柱法在磨坊矿的应用

磨坊矿结合生产实际,设计采用分层开采的切顶房柱采矿法开采缓倾斜中厚矿体。实践证明,分层开采的切顶房柱采矿法具有损失率低、贫化率低、回采率高、工艺技术简单等优点。     

氢氧根与硫氢根协同效应对胺法浮选异极矿的影响

针对难选异极矿的浮选特点,通过纯矿物浮选、红外光谱测试和实际矿石浮选研究了异极矿浮选中氢氧根离子和硫氢根离子之间的协同效应。研究结果表明,硫化钠中氢氧根离子和硫氢根离子在异极矿的浮选中都具有活化异极矿的作用,但氢氧根离子对矿物活化的选择性和效果不如硫氢根离子,在pH=9～11之间,氢氧根离子和硫氢根离子具有明显的协同效应,提高了异极矿的回收率,降低了硫化钠的活化浓度。实际矿石浮选试验结果证实了纯矿物试验的结论,在减少一半硫化钠用量的条件下,通过添加氢氧化钠可以获得较好的硫化胺工艺浮选异极矿的指标。     

用新型抑制剂提高长坡选厂铅锑精矿品位

采用广西大学研制的新型有机抑制剂GZT,进行了降低长坡选矿厂铅锑精矿杂质含量、提高精矿铅锑品位的实验室小型试验和工业试验。试验结果表明,GZT是一种非常有效的硫化矿选择性抑制剂,工业试验中将长坡选厂铅锑精矿的铅+锑品位提高了9.61个百分点,铅锑精矿中的锌含量降低了2.97个百分点,同时铅和锑的回收率分别提高了4.75和4.19个百分点,使长坡选矿厂铅锑精矿品位偏低的问题得到了明显改善。     

Mobility and redistribution of waters within bighead carp (Aristichthys nobilis) heat-induced myosin gels

Water-holding capacity is closely related to gel microstructure, and is a very important quality trait in surimi and surimi product. The changes in the secondary structure, gel microstructure, and the migration of water in bighead carp (Aristichthys nobilis) myosin gel induced by different temperatures (50–90°C) were investigated. The α-helical structure of myosin decreased at temperatures of 40°C or higher. The fractal dimension of the gels increased at 40, 50, and 60°C, but decreased at temperatures over 60°C. The pore size of the gels increased with temperatures up to 50°C, decreased at 60°C, and then increased with temperatures up to 90°C again. The transverse relaxation times also varied; T₂₁ remained constant at temperatures over 40°C; T₂₂ decreased at temperatures lower than 50°C, increased at 60°C, and then decreased with temperatures up to 90°C; and T₂₃ increased at temperatures lower than 50°C and then remained constant until 90°C. Principal component analysis showed that the proportion of T₂₂ water (PT₂₂) was inversely correlated with the unfolding of myosin, whereas directly correlated with the pore size. The proportion of T₂₃ water (PT₂₃) was positively correlated with the fractal dimensions of the gels, whereas negatively correlated with the pore size. The migration of the secondary layer of water was mainly caused by hydrophobic force and the physical space formed by the myosin backbone, and the migration of water within the third layer was mainly caused by capillary pressure. Therefore, the mobility and redistribution of waters depend on the water retention mechanism, which is determined by the physical structure of gels. This study provides further information about the relationship between the NMR data, gel microstructure, water mobility, and distribution.     

Evaluation of SPE as Preparative Technique for the Analysis of Phenolic Metabolites in Human Feces

Solid phase extraction (SPE) methodology has been evaluated as a cleanup strategy prior to the analysis of phenolic metabolites in fecal samples by UPLC–DAD–ESI–TQ MS. Among the sorbents tested, Oasis® HLB led to the higher phenolic standard recoveries. Sample acidification (0.4 M HCl, final concentration) before SPE considerably improved standard recoveries. Values of the process efficiency (C_SPE/C_{Without SPE}) for a standard solution containing gallic acid, protocatechuic acid, caffeic acid, benzoic acid, 3-phenylpropionic acid, (+)-catechin, (?)-epicatechin, procyanidin B2, and 4-hydroxybenzoic 2,3,5,6 d₄ acid were acceptable (>90 %) for all compounds, except for procyanidin B2 (26 %). The developed SPE methodology was applied to fecal samples of individuals subjected to a wine intervention study. Phenolic metabolites, including intermediate metabolites (phenyl-γ-valerolactones and phenylvaleric acid derivatives) and end products (simple phenols, hydroxyphenylpropionic, hydroxyphenylacetic, hydroxycinnamic, and hydroxybenzoic acids) were identified. Most of the compounds (n?=?14) exhibited values of process efficiency between 85 and 115 %. Although some compounds (n?=?4) showed process efficiency>115 %, there was a group of metabolites (4-O-methylgallic acid, syringic acid, and 4-hydroxy-5-(3′,4′-dihydroxyphenyl)-valeric acid) whose process efficiency was <85 %, which represented a serious limitation and made us to discard SPE as a preparative technique for the analysis of these phenolic metabolites. Finally, the paper reports the concentrations of phenolic metabolites in a randomized set of human fecal samples from healthy volunteers (n?=?15) without any previous SPE application. Large inter-individual variability was observed, which was attributed to differences in human gut microbiota composition.     

The amino acid composition,solubility and emulsifying properties of sweet potato protein

A protein was purified from the high-protein type sweet potato variety 55-2 available in China. The amino acid composition, solubility and emulsifying properties of the sweet potato protein (SPP) were studied. The SPP was rich in aspartic acid (18.5%) and glutamic acid (9.30%) while essential acid amino acids made up approximately 40.7% of the SPP. The SPP was highly soluble in distilled water over a wide range of pH. However, solubility of the SPP in 1.0 M NaCl and 1.0 M CaCl₂ solutions was low especially at pH below the pI of the SPP. The SPP in CaCl₂ demonstrated emulsifying activity index (EAI) and emulsion stability index (ESI) many folds higher than those in distilled water and NaCl solution (P < 0.05).     

浸出制油技术研究进展

与压榨法制油技术相比,浸出制油法技术具有诸多优点,但现行油脂工业浸出制油技术的应用因健康及环保问题受到人们的不断质疑.为此,各国油脂科技工作者对新型浸出制油技术的新型替代溶剂筛选及其应用展开了大量的研究工作.其中,以饱和烃类溶剂、低碳链醇类溶剂、超临界二氧化碳及酶法浸出技术为目前的研究热点.就以上浸出技术的最新进展进行综述,重点介绍其工艺、装备及安全、环保等,以供业界参考.     

Effects of Salvia officinalis and Thymus vulgaris on oxidant-induced DNA damage and antioxidant status in HepG2 cells

Salvia officinalis (SO) and Thymus vulgaris (TV) are medicinal plants well known for their curative powers. However, the molecular mechanisms responsible for these abilities of sage and thyme have not been fully understood yet. In this study we investigated the composition and the quantitative estimation of plant extracts, the protective effects of plant extracts against hydrogen peroxide- and 2,3-dimethoxy-1,4-naphthoquinone-induced DNA damage, and levels of enzymatic and non-enzymatic antioxidants (superoxide dismutase, glutathione peroxidase, glutathione) in human HepG2 cells. To measure antioxidative activity of plant extracts we used three assays: 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The results showed that the oxidant-induced DNA lesions were significantly reduced in cells pre-treated with the plant extracts studied. The observed DNA-protective activity could be explained by both elevation of GPx activity in cells pre-treated with SO and TV and antioxidant activity of SO and TV.