Optimised phase compositions and improved microwave dielectric properties based on calcium tin silicates

The Ca_(1+2y)Sn_(1-x)Si_(1+y)O_(5-2x+4y) low-permittivity microwave dielectric ceramics were prepared through solid-state reaction at 1350–1450 °C for 5 h. The relations between microwave dielectric properties and phase compositions for non-stoichiometric Ca_(1+2y)Sn_(1-x)Si_(1+y)O_(5-2x+4y) ceramics have been investigated. A single CaSnSiO₅ phase with abnormally positive temperature coefficient of resonant frequency (τ_f = + 62.5 ppm/°C) was synthesised at 1450 °C. This composition was an effective τ_f compensator of CaSiO₃ and Ca₃SnSi₂O₉ phases with typically negative τ_f value. The CaSiO₃ second phase was related to the Sn deficiency in the CaSn_(1-x)SiO_(5-2x) (0 < x < 1.0) composition, whereas the Ca₃SnSi₂O₉ second phase was obtained by controlling the Ca:Sn:Si ratios on the basis of the Ca_(1+2y)SnSi_(1+y)O_(5+4y) (0 < y < 1.0) composition. A promising low-permittivity millimetre-wave ceramic with most excellent microwave dielectric properties (ε_r = 10.2, Q×f = 81,000 GHz and τ_f = −4.8 ppm/°C) was produced from the Ca_(1+2y)SnSi_(1+y)O_(5+4y) (y = 0.4) ceramic.     

Effects of zirconium silicate and chromite addition on the microstructure and bulk density of magnesia–magnesium aluminate spinel-based refractory materials

Six synthesized magnesium aluminate spinel-based refractory compositions used in steel and cement applications, were prepared using a two stage sintering process at 1760 °C, starting with approximately 1:1 wt% ratio of pure magnesia and alumina with additions of zirconium silicate (0.5, 1.0 and 2.0 wt%) and chromite (2.0, 3.0 and 5.0 wt%). These compositions were investigated for effects on densification, chemical and mineralogical phases formed.     

Equitone Predicate Algebras and Their Applications

Predicates that preserve their values on a larger (extended) body of data are called equitone. An algebra of such predicates is constructed, a system of its generators is specified, and a complete system of transformations of identities is defined. The results obtained are used for construction and investigation of complete classes of compositions of various types and levels of abstractions that are used in logics of partial predicates.     

兰香草挥发油化学成分的研究

采用常压水蒸气蒸馏法提取了兰香草挥发油,得油率为 0.35 ~ 0.52%。其相对密度(20℃/4℃)0.9980 ~0.9900,折射率(20℃)1.4608,比旋光度+0.51°;酸值1.5。并用毛细管气相色谱、红外光谱、核磁共振谱和色-质联机等对该挥发油进行了系统的成分分析。在分出的112个色谱峰中,共鉴定出 71 个化合物,占挥发油总量的 94.6%。其主要成分为芳樟醇、紫苏醇、香芹酮、荠苎烯、4-甲基-6-庚烯-3-酮、葎草烯、马鞭草烯酮、左旋松香芹酮、2-壬烯-4-炔等。     

浅析预焙阳极配料控制

分析了粉料纯度及配料控制对炭阳极生产和炭阳极成品率的影响，结合中国铝业青海分公司的生产状况，从预焙阳极配料控制方面，就如何提高炭阳极成品率、保持生阳极生产工艺稳定进行论述。     

矩形断面明渠中恒定均匀流的机械能损失

明渠流中机械能损失的确定是水力学乃至工程流体力学中的重要内容.以构建的明渠恒定流新的总流能量方程及矩形断面明渠三维层流运动的理论解为基础,通过理论分析与三维数值计算,就矩形断面明渠中恒定均匀流的机械能损失系数随雷诺数及宽深比的变化进行了深化研究,得到如下成果:1)在层流条件下,机械能损失系数一般均与雷诺数和宽深比有关,只有对宽深比大于6.5的宽浅明渠,其相应流动的机械能损失系数才仅与雷诺数有关,且在雷诺数相同的条件下,一般矩形断面明渠流的机械能损失系数要大于宽浅明渠流的机械能损失系数;2)在紊流条件下,机械能损失系数也一般均随雷诺数与宽深比而变,但对给定的宽深比,存在相应的特征雷诺数,当流动的实际雷诺数大于该特征雷诺数后,机械能损失系数则不再随宽深比而变化,且在宽深比一定的条件下,雷诺数越小,其机械能损失系数的修正值越大.     

Restricted compositions and permutations: From old to new Gray codes

Any Gray code for a set of combinatorial objects defines a total order relation on this set: x is less than y if and only if y occurs after x in the Gray code list. Let ? denote the order relation induced by the classical Gray code for the product set (the natural extension of the Binary Reflected Gray Code to k-ary tuples). The restriction of ? to the set of compositions and bounded compositions gives known Gray codes for those sets. Here we show that ? restricted to the set of bounded compositions of an interval yields still a Gray code. An n-composition of an interval is an n-tuple of integers whose sum lies between two integers; and the set of bounded n-compositions of an interval simultaneously generalizes product set and compositions of an integer, and so ? put under a single roof all these Gray codes.As a byproduct we obtain Gray codes for permutations with a number of inversions lying between two integers, and with even/odd number of inversions or cycles. Such particular classes of permutations are used to solve some computational difficult problems.     

基于WEB模式招投标决策系统的分析与研究

介绍了目前设备采购招投标的现状与存在的问题，并分析和建立了网上招投标系统的体系结构、网络架构和功能结构。利用决策支持系统理论中的层次分析法评定中标企业，该层次分析法思想简洁、使用灵活，能够成功地应用于中标方的评定，特别是对于缺少定量数据进行定性判断的情况。在此基础上，开发出了基于WEB模式采购招投标系统，经实际应用，该招标系统与传统的招标管理相比，充分体现招投标工作的“透明”特征，发扬“公平、公开、公正”的原则。     

紫菜酶解物的制备及其特性

坛紫菜用纤维素酶和木瓜蛋白酶分别或联合处理,考察了提取物的得率、DPPH自由基清除率、氨基酸组成、蛋白溶解性和乳化性等性质。结果发现,利用木瓜蛋白酶对紫菜进行酶解时,固形物提取率稍微高于纤维素酶,利用这两种酶进行复合酶解时虽然可以提高紫菜的固形物得率,但不会改变蛋白提取率。紫菜酶解物的DPPH自由基清除率与蛋白含量之间存在显著的正相关关系,可能与提取物中具有抗氧化活性的氨基酸含量增加有关。另一方面,紫菜经复合酶酶解4h以上,提取物的蛋白溶解性在任一pH下都接近100%。而且,紫菜酶解物的乳化性在pH9最好,但乳化稳定性在pH7最低。      

不同品种黍子营养成分及功能活性成分差异化分析

目的:研究黍子营养及功能活性成分的品种差异化。方法:选取8个品种的黍子,对水分和灰分等基本组分和淀粉、蛋白质、脂肪等营养组分及多酚、黄酮、低聚糖等功能活性成分的含量进行了检测分析。结果表明:不同品种黍子样品中,基本组分水分的变异系数为8.43%,变幅为9.38%~12.39%;灰分的变异系数为23.48%,变幅为0.94%~1.79%。营养组分粗淀粉的变异系数为2.77%,品种间含量较为稳定,但冀张黍1号和安塞黄糜子所含慢消化淀粉和抗性淀粉含量比例相对较高;粗蛋白的变异系数为8.04%,品种之间差异显著(p<0.05),其中龙黍18总氨基酸最高,约为149.06 mg/g,且必需氨基酸可达总氨基酸含量的44.54%;此外,粗脂肪的变异系数为23.23%,品种之间差异显著(p<0.05),其中宁糜9号不饱和脂肪酸占总脂肪酸比例最高,为87.06%。功能活性成分中,总黄酮的含量差异最为显著,变异系数为73.07%,变幅为0.89~10.17 mg/g;总多酚含量变异系数为67.78%,变幅为0.74~3.44 mg/g;同时,低聚糖含量的品种间差异也较大。本研究结果对于保留和选育黍子优良品种及黍子食品和保健品的开发具有指导意义。