Detection and Molecular Characterization of <i>Cronobacter sakazakii</i>Isolated from Powdered Infant Formula (PIF) from North Central Region, Nigeria

Cronobacter sakazakii is an emerging ubiquitous and opportunistic pathogen that currently contaminates a wide spectrum of foods including powdered milk and poses a lethal threat to neonates, the elderly and persons with immune deficiencies. They cause life threatening neonatal meningitis, septicemia, and necrotizing enterocolitis. A total of 360 samples of powdered infant formula were collected from postnatal hospital attendees reconstituting the PIF for their children in the North Central region of Nigeria where cases of infant mortality are very high and presenting as enterocolitis and diarrhea. Pre-enriched samples were cultured in chromogenic Cronobacter broth and were then further sub-cultured into a chromogenic Cronobacter sakazakii agar. They were positive, exhibiting yellowish cultures typical of Cronobacter sakazakii. Biochemical tests of the isolates were also carried out and indicated the presence of Cronobacter sakazakii. The isolates were then characterized molecularly using specie specific PCR detection of Cronobacter sakazakii. The targeted genes of interest were ompA gene and CPA gene. The isolates tested showed bands for ompA gene on electrophoresis imager and were confirmed as Cronobacter sakazakii. In Nigeria, majority of infants are still fed with PIF. There is no existing data on the detection of Cronobacter sakazakii previously reported in the North central region of Nigeria hence the need to carry out the present study. The result of the study demonstrated the need for effective prevention and control measures as contamination of PIF with Cronobacter sakazakii constituted potential public health risk to neonates and infants.

Characterization of Clay of the Benin Used in Ruminale Feeding. Complete Determination of the Smectites Contained in These Clays

In this work, by the use of several physico-chemical complementary methods for the characterization of soil (diffraction of x-rays, chemical analysis, density, cationic exchange capacity, specific sur faces, m?ssbauer, granulometry, etc.), the smectite of the three clayey localities of Benin (Gbédji-Kotovi, Massi-Sèhouè and Zogbodomey) was notably studied. Thus, these three sites principally contain principally smectite, kaolinite and quartz in variable proportion. This smectite is a beidellite. Its chemical formula is proposed. The specific surfaces and the cationic exchange capacity of the samples are determined. For these samples, the fraction lower than 2 μm is practically beidellitic for Gbédji-Kotovi and Massi-Sèhouè (more than 82% of beidellite) and practically kaolinitic (70% of kaolinite) for Zogbodomey. So, used as additive food to ruminant, the clay of Gbédji-Kotovi and Massi-Sèhouè will induce an enteric reduction of methane more than clay of Zogbodomey.

盐溶液对石英粉-膨润土混合土渗透系数的影响与表征

采用变水头渗透试验对蒸馏水与不同浓度的NaCl、CaCl2溶液下石英粉-膨润土混合土的渗透系数进行了测定,为探讨盐溶液及膨润土含量对混合物渗透系数的影响作用机理,使用核磁共振试验(MRI)、环境扫描电镜(ESEM)对混合物在不同盐度溶液下的孔隙分布特征进行分析。结果表明:在盐溶液作用下,石英粉-膨润土混合土的渗透系数明显增加,其孔隙分布也具有明显的差异。推断盐溶液对渗透系数的影响是由于混合土的孔隙变化引起的。最后利用黏粒孔隙比(eb)的概念,建立了一种考虑盐溶液作用下石英粉-膨润土混合土渗透系数的表征公式,与已有预测公式相比,新建表征公式能够较好地预测盐溶液作用下石英粉-膨润土混合土的渗透系数。

核电站汽轮机运行性能监测与诊断

就核电汽轮机与火电汽轮机的差异以及由此差异引起的湿蒸汽汽轮机通流性能表征与热平衡计算的难点进行了论述,提出了利用特征通流面积CFA来表征核电汽轮机的通流性能和采用小误差热平衡法来计算核电汽轮机的热平衡图,应用小误差热平衡法和特征通流面积成功开发了核电站热力性能在线监测与分析系统和核电站汽轮机全面热力试验计算软件,并将这两项技术应用在大亚湾核电机组热力性能在线监测与分析系统和岭澳二期核电机组全面热力试验中.结果表明:实际运行监测中特征通流面积监测值的测量精度可控制在1%以内.

辣椒素固体分散体的处方工艺优化及表征

目的:制备辣椒素固体分散体,优化其处方工艺,并进行表征。方法:采用熔融法,以泊洛沙姆188(P188)或聚乙二醇4000(PEG4000)为载体制备辣椒素固体分散体。以60min的累积释放度为指标,采用正交试验设计优化载体种类、药载比及搅拌时间,并进行验证;考察所制辣椒素固体分散体在温度40℃、相对湿度75%条件下0、30、180d内的稳定性及X射线衍射法(XRD)分析是否有新峰出现;利用差示扫描量热法(DSC)、XRD对其进行物相表征。结果:以P188-PEG4000为载体,辣椒素-P188-PEG4000的质量比为1∶5∶3,搅拌20min,所制辣椒素固体分散体体外60min的累积释放度为84.6%(n=3),180d内稳定性良好[含量RSD为3%(n=3),XRD显示未出现新峰];物相表征证明,辣椒素以无定型状态或分子状态高度分散于载体中。结论:通过此工艺制备了辣椒素固体分散体并且在60min可体外溶出80%以上,稳定性好,工艺简便可行。

纯丙微乳液的合成与表征

采用预乳化半连续滴加方法，用甲基丙烯酸甲酯、丙烯酸丁酯、甲基丙烯酸，合成了纯丙微乳液，确定了最佳配方。探讨了软硬单体配比、乳化剂用量以及阴／非离子乳化剂配比、pH值以及聚合工艺中反应温度、反应时间对纯丙微乳液聚合稳定性、乳液性能及外观的影响。结果表明，当硬软单体的配比为5：4、乳化剂的配比为4：1、乳化剂的用量为3％、引发剂的用量为0．5％、pH在7—8、反应温度为80～88℃、反应时间为150min时，微乳液的性能最好。并对共聚物的结构和微乳液涂膜应用傅立叶红外光谱（FTIR）进行表征，测试结果表明丙烯酸酯类单体之间发生了自由基共聚反应。

奥里诺科重油带MPE-3区块Oficina组辫状河三角洲沉积相定量刻画

委内瑞拉盆地奥里诺科重油带MPE-3区块Oficina组辫状河三角洲沉积相定量刻画难度大,是制约该区块水平井高效开发的关键地质因素。在区域沉积背景研究的基础上,利用岩芯描述和分析化验资料,确定该地区为辫状河三角洲沉积,区内主要发育辫状河三角洲平原和三角洲前缘亚相,心滩、复合心滩坝、辫状河道、决口扇/溢岸、泛滥平原、水下分流河道、分流间湾、席状砂和潮汐砂坝等微相。综合利用地震和测井资料、现代沉积测量类比和经验公式等三种方法,实现了研究区主要沉积微相的定量刻画,认为辫状河河道带宽度介于1~5 km,水下分流河道宽度在1 km左右,建立了心滩宽与心滩长、心滩宽与辫状河道宽度、水下分流河道单河道宽度与深度之间关系的经验公式,进一步阐明了Oficina组沉积时期辫状河三角洲沉积演化规律,为提高研究区超重油油藏采出程度提供了重要地质依据。

三七配方颗粒新型制备工艺研究及表征

目的:通过对比分析配方颗粒的吸湿性以及IR、DSC、XRD和SEM等表征结果,考察新型制备工艺的合理性与可行性。方法:通过考察不同混合方式下的三七配方颗粒的吸湿性,同时运用IR、XRD、DSC和SEM等分析手段对配方颗粒进行表征。结果:通过对比5种常用辅料,新型混合工艺制备的配方颗粒的平衡吸湿量较传统工艺降低范围在18%~30%,平衡时间延长范围在13%~17%;经新型混合工艺制备的配方颗粒其药物有效成分与辅料未发生物理与化学变化,提取物在颗粒中更多以无定形或微晶形式存在,同时颗粒表面结构有较大改观。结论:新型工艺制备的配方颗粒吸湿性较好,提取物与辅料未发生物理化学变化,表面结构平整光滑,说明新型制备工艺适用于中药配方颗粒的生产。

丁香苦苷固体脂质纳米粒的制备及表征

目的:制备丁香苦苷固体脂质纳米粒(SYR-SLN),优化处方,并对其进行表征。方法:采用乳化蒸发法制备SYR-SLN,以包封率为指标,在单因素试验考察基础上,通过正交试验设计对处方中卵磷脂-单甘酯质量比、有机相-水相体积比、泊洛沙姆188(F68)浓度、投药量进行优化,确定最优处方工艺,考察所制纳米粒的包封率、载药量、形态、粒径、Zeta电位、稳定性等。结果:卵磷脂-单甘酯质量比为3∶240 mg、F68浓度0.4%、SYR 10 mg、无水乙醇5 mL、蒸馏水10 mL,乳化温度为65℃,搅拌速度为600 r/min。所得SYR-SLN的包封率为(42.35±0.60)%(n=3),载药量为(5.33±0.03)%(n=3),其外观圆整,分布均匀,平均粒径为(180.30±5.31)nm,Zeta电位为(-41.9±0.8)mV,4℃条件下贮存15 d稳定性良好。结论:本方法成功制得SYR-SLN,且处方工艺简单,包封率高。

基于魔术公式的轮胎特征函数计算方法

提出了利用魔术公式(magic formula)计算轮胎特征函数的方法。基于轮胎力学特性试验数据辨识得到magic formula轮胎模型中的相关系数。根据magic formula轮胎模型可以计算轮胎在任意载荷、任意运动状态下与操纵稳定性相关的性能指标,用来进行性能的集成;同时可以作为对轮胎特性的要求,提供给轮胎供应商作为性能开发的基准。以某一车型轮胎选型过程中轮胎特征函数的计算为例,说明了具体的实现过程,此方法提高了汽车操纵稳定性匹配与性能集成的精度与效率,具有实际的工程意义。

TC11钛合金高周疲劳性能的定量表征

基于郑公式,从应力比和应力集中系数与疲劳寿命之间的关系出发,得到了TC11钛合金高周疲劳性能归一化模型的数学表达式。结果表明:公式Nf=Sf(Sa-Sac)-2可以有效地拟合TC11钛合金在不同应力集中系数和应力比条件下的疲劳试验数据;而使用公式Nf=Sf[Segv-(Segv)c]-2能有效地归一化处理TC11钛合金的疲劳试验数据,获得的归一化数学模型表达式为:Nf=4.14×109(Segv-424.58)-2。

基于东北特色食材的鱼香肉丝预调食品配方优化及其成品菜挥发物成分表征研究

鱼香肉丝菜品选材的优劣直接决定菜品的营养价值和适口性。该研究采用响应面方法优化了东北笨猪里脊肉、胡萝卜、木耳添加量对鱼香肉丝菜品品质的影响;利用顶空固相微萃取-气质联用技术分析了成品菜的挥发物成分与含量。响应面优化结果显示:里脊肉的添加量为312.57 g,木耳的添加量为102.37 g,胡萝卜的添加量为100.39 g,实现了最高感官评分值;气质分析结果表明,从成品菜中共检测到49种挥发性物质,其中醇类、醛类、烯类化合物为该菜品的主要物质类型,乙酸乙酯为该菜品酯香味呈味物质。该研究成果为后续鱼香肉丝的预调理食品货架贮藏与成品菜制作提供了重要的数据参考信息。

Analyses of Dynamic Rheological Behavior of Polymer Melt Based on Novel Experimental Equipment and Procedures

By introducing a vibrating force field into the extrusion process of polymer melt, an experimental equipment of constant velocity type dynamic rheometer of capillary (CVDRC) was designed. A set of experimental procedures was established, by which the dynamic rheological parameters of polymer can be acquired, and a set of data management methods to undergo time-domain or frequency-domain analysis was set up for dynamic rheological data of polymer melt. Meantime, the characterization formula of polymer melt's rheological behavior in a vibrating force field was set up. The instantaneous value of capillary entry pressure, capillary volume flow rate and their phase difference were measured and analyzed, and the melt apparent viscosity, which describes the rheological behavior of polymer melt in a vibrating force field, was obtained.

景德镇传统粉彩颜料概述

粉彩瓷是景德镇四大传统名瓷之一,其中粉彩瓷装饰用颜料是关键。文章整理了传统粉彩颜料的配方组成与制备方法,叙述了粉彩颜料的分类,归纳了景德镇传统粉彩颜料的主要原料及其性能与作用,列出了有关键作用的玻璃白颜料以及利用胶体着色的金红颜料色剂紫金泥的测试表征结果,总结得出相关结论。

各向异性Besov和Triebel-Lizorkin空间的一种刻画

借助于各向异性函数空间的性质和Littlewood-Paley理论,应用恒等逼近算子族,得到了各向异性空间上的Calderón型再生公式.继而,作者利用Calderón型再生公式对各向异性的Besov空间和Triebel-Lizorkin空间进行了刻画.所有这些结果都没有使用Fourier变换和卷积.

模拟含Pu放射性废物的硼硅酸盐玻璃固化体制备及其耐水性测试

针对含Pu这类特殊废物,本实验以镧系元素Ce模拟放射性核素Pu,通过设计新的硼硅酸盐玻璃配方,制备了系列包含不同CeO_2的玻璃样品。工艺特性实验结果表明:当CeO_2含量为4%~7%时,玻璃液流动性好,高温黏度低,成型玻璃表面及内部无气泡和析出相,样品质量好。同时,玻璃具有较高的Tg值(>670℃)预示着其热稳定性好。SEM(EDS)检测数据说明:Ce的X射线特征亮斑随理论Ce含量的增加而逐渐增多,且在玻璃基体上分布均匀,无明显团聚、偏析现象;CeO_2在制备过程中存在一定程度的损失,但与Gd_2O_3、SiO_2的质量百分比仍接近理论设计值,确保了玻璃的固有性能不会产生较大改变。耐水性实验结果表明:当CeO_2含量≤6 wt%时,样品的碱析出量达到国家标准(Ⅰ级),且随CeO_2含量的增加而减少,样品耐水性好;当CeO_2含量为7 wt%时,样品碱析出量不再满足国标要求(>Ⅰ级)。因此,从工艺和性能角度考虑,本实验设计的玻璃组分对CeO_2的最大包容量可达到6%,且样品的综合性能满足固化要求。

DOUBLE-MARKOV RISK MODEL

Given a new Double-Markov risk model DM = （μ, Q, v, H; Y, Z） and Double-Markov risk process U = {U（t）, t 〉 0}. The ruin or survival problem is addressed. Equations which the survival probability satisfied and the formulas of calculating survival probability are obtained. Recursion formulas of calculating the survival probability and analytic expression of recursion items are obtained. The conclusions are expressed by Q matrix for a Markov chain and transition probabilities for another Markov Chain.

油页岩临界热解中间体的结构表征

为探究抚顺油页岩有机质热解机理,以其热解产物抽提率最高时获得有机体——临界热解中间体为研究对象,采用核磁共振(NMR)、傅里叶红外光谱(FTIR)、X射线光电子能谱(XPS)、快速裂解气相色谱质谱联用(Py-GC/MS)技术对临界热解中间体进行了原子结构表征,提出了该热解中间体平均分子结构模型的分子式C_(370)H_(570)O_(29)N_(4)S.结果表明:临界热解中间体的碳骨架结构主要由脂肪族碳构成,脂碳率与芳碳率分别为74.7%和25.3%,脂肪烷烃链的支化度Bi为4.31%,亚甲基长链的平均碳数约为18个;芳香碳以单环形式为主,芳香环的平均取代程度为0.4左右;杂原子主要以羰基氧、吡咯氮和噻吩硫的赋存形式存在.

A characterization of answer sets for logic programs

Checking if a program has an answer set, and if so, compute its answer sets are just some of the important problems In answer set logic progremming. Solving these problems using Gelfond and Llfschltz＇s original definition of answer sets Is not an easy task. Alternative charaoterlzatlons of answer sets for nested logic programs by Erdem and Llfschltz, Lee and Llfschltz, and You at el. are based on the completion semantics and various notions of tlghtnese. However, the notion of tightness Is a local notion In the sense that for different answer sets there are, In general, different level mappings capturing their tlghtnese. This makes It hard to be used In the deelgn of algorithms for computing answer sets. This paper proposes a charecterization of answer sets based on sets of generetlng rules. From this charaoterlzation new algorithms are derived for computing answer sets and for performing some other reasoning teaks. As an application of the charecterlzatlon a sufficient and necessary condition for the equivalence between answer set sementics and completion semantics has been proven, and a basic theorem Is shown on computing answer sets for nested logic programs baaed on an extended notion of loop formulas. These results on tlghtnese and loop formulas are more general than that in You and Lin＇a work.

赤芍标准汤剂质量表征参数的探索性研究

针对标准汤剂质量表征参数不完善的情况,对赤芍配方颗粒进行综合性评价研究,以探索标准汤剂质量表征方法.在《中药配方颗粒质量控制与标准制定技术要求》(以下简称《技术要求》)中规定的特征图谱、出膏率及有效成分含量指标的基础上,增加物理与紫外指纹图谱及活化部分凝血活酶时间等指标对赤芍标准汤剂与配方颗粒进行研究比对,采用SPSS软件进行统计分析.结果显示,各批次赤芍配方颗粒出膏率及芍药苷含量均在《技术要求》规定可允许范围内,赤芍标准汤剂与配方颗粒的物理及紫外指纹图谱相似度较高,但配方颗粒的流动性、防潮性、活性成分及活血药效与标准汤剂有显著性差异,配方颗粒优于标准汤剂.表明目前《技术要求》中规定的参数并不能完全表征标准汤剂与配方颗粒的质量属性,有待进一步丰富.