Lipoprotein(a): Nonhuman primate models

Lipoprotein(a) [Lp(a)] is a low density lipoprotein which has apo(a) disulfide-linked to apoB100. Apo(a) has recently been shown to have a striking homology with plasminogen, a knowledge that has stimulated a lot of interest in the mechanism of atherogenicity and thrombogenicity of this lipoprotein particle. Several studies have documented the presence of Lp(a) in nonhuman primates with particular reference to the rhesus monkeys and baboons. The Lp(a) of rhesus monkey is structurally very similar to that of humans, except for the absence of kringle V and the amino acid composition of the catalytic region. The Lp(a) of nonhuman primates, like their human counterparts, exhibit a wide range of interindividual plasma levels and also a wide size polymorphism of apo(a). Nonhuman primates appear to represent a good model for the study of the structure and biology of Lp(a).     

Successful utilization of lyophilized lipoprotein(a) as a biological reagent

Lipoprotein(a) [Lp(a)] represents a class of lipoprotein particles having as a protein moiety apoB-100 linked by a single disulfide bond to apolipoprotein(a) [apo(a)], a multikringle structure with a high degree of homology with plasminogen. A recognized feature of Lp(a) is its instability on storage caused by attendant protein and lipid modifications that affect the structural, functional, and immunological properties of this lipoprotein. Here we present data showing that, under appropriate conditions of cryopreservation, Lp(a) retains the properties of the freshly isolated product, and we provide examples supporting the stability of this cryopreserved product as a primary standard in immunoassay settings and in cell culture systems.     

Metabolization of the Polycyclic Aromatic Hydrocarbon Benzo( A )Pyrene by a Non-White Rot Fungus ( Fusarium Solani ) in a Batch Reactor

To investigate metabolization of benzo[ a ]pyrene (B a P), a high-molecular-weight polycyclic aromatic hydrocarbon consisting of five aromatic rings, by a Deuteromycete Fusarium solani , a culture with [7,10- 14 C]benzo[ a ]pyrene was carried out in a batch fermentor under cometabolic conditions. In spite of drastic culture conditions with a high load of B a P (302 mg in a 1.6 liters), analysis of the growth and substrate depletion kinetics showed a classical pattern. The evolution of 14 CO 2 release demonstrated that B a P mineralization by the non-white rot fungus F. solani occurred rapidly at early stages of fermentation (15 hr) during the germination process. At the end of fermentation, 1.2% of the B a P was evolved as 14 CO 2 and 5.3% was incorporated in biomass. B a P metabolization was also confirmed by isolating metabolic products, extracted from mycelia and identified as 1,6-benzo[ a ]pyrene quinone and 3,6-benzo[ a ]pyrene quinone, by mass and ultraviolet (UV) spectroscopic analyses.     

Analysis of the process of the countercurrent cyclic chromatography

Cyclic countercurrent chromatography, a new method of liquid chromatography, has been considered. A mathematical model of a cyclic process has been developed. Each cycle consists of two half-periods, i.e., a half-period of the motion of a light phase (a heavy phase plays a role of an immobile phase) and a half-period of the motion of a heavy phase (a light phase plays a role of an immobile phase). Sampling is introduced in the form of a pulse into the average zone of a system of sequentially connected equilibrium steps into the half-period of the motion of the light phase of the initial process cycle. Analytical dependences for calculating the cyclic processes of the countercurrent chromatography have been derived. The experiment and the theory are correlated, and satisfactory agreement between the experimental results and computational investigations has been established.     

A fryer design with constant specific surface area

The specific surface area (surface area/volume) of a traditional frying vessel with a rectangular profile increases as the oil level decreases. In order to maintain a constant specific surface area of frying oil regardless of oil consumption, a special fryer was designed and constructed. The specific surface area of a frying vessel having a linear-inclined profile (Valentine batch fryer) deviated from a constant value by a maximum of 7.5%. The specific surface area of a frying vessel with an exponentially curved profile maintained a constant specific surface area even though the oil level varied.     

Effect of packing density and adsorption parameters on the throughput of a thermal compressor

Vapour adsorption refrigeration systems (VAdS) have the advantage of scalability over a wide range of capacities ranging from a few watts to several kilowatts. In the first instance, the design of a system requires the characteristics of the adsorbate–adsorbent pair. Invariably, the void volume in the adsorbent reduces the throughput of the thermal compressor in a manner similar to the clearance volume in a reciprocating compressor. This paper presents a study of the activated carbon +HFC-134a (1,1,1,2-tetrafluoroethane) system as a possible pair for a typical refrigeration application. The aim of this study is to unfold the nexus between the adsorption parameters, achievable packing densities of charcoal and throughput of a thermal compressor. It is shown that for a thermal compressor, the adsorbent should not only have a high surface area, but should also be able to provide a high packing density. Given the adsorption characteristics of an adsorbent–adsorbate pair and the operating conditions, this paper discloses a method for the calculation of the minimum packing density necessary for an effective throughput of a thermal compressor.     

A Wavelet-Based Test for Stationarity

We develop a test for stationarity of a time series against the alternative of a time-varying covariance structure. Using localized versions of the periodogram, we obtain empirical versions of a reasonable notion of a time-varying spectral density. Coefficients with respect to a Haar wavelet series expansion of such a time-varying periodogram are an indicator of whether there is some deviation from covariance stationarity. We propose a test based on the limit distribution of these empirical coefficients.     

Filamentary extrusion of microcellular polymers using a rapid decompressive element

An extrusion process for manufacturing microcellular plastics is presented. In the past, microcellular structures have been produced in batch processes by using a thermodynamic instability of a polymer/gas system. In order to utilize such a thermodynamic instability in a continuous extrusion process, a large amount of gas must be dissolved quickly in a molten plastic flowing in the machine, and a rapid drop in the gas solubility must be induced in the flowing polymer/gas solution. Since the solubility of a gas in a polymer is a sensitive function of pressure, a thermodynamic instability for producing a microcellular structure can be induced by rapidly lowering the pressure. This paper presents a means for continuously forming the polymer/gas solution at an industrial processing rate and a means of nucleating microcells in the polymer/gas solution using a nozzle. Finally, a process model for controlling the cell morphology is presented by identifying the key parameters that control microcellular foaming in a continuous process. The experimental results agree with theoretical analyses, confirming the fact that the processing pressure strongly affects the microcellular foaming process through its effects on the amount of gas dissolved in the polymer and the magnitude of the pressure drop in the nucleation device.     

Bistability of propagating front with spin‐mode in a frontal polymerization of trimethylopropane triacrylate

We have studied a nonlinear dynamic behaviour in a frontal polymerization process. Frontal polymerization is a mode of converting a monomer into a polymer via a localized reaction zone that propagates as a front. Interest in studying the dynamic behaviour of such propagating fronts is growing. Many studies focus on the spin‐mode front propagation characterized by a nonplanar front having one or more high temperature regions which move in a helical path along the axis of the reaction vessel. In this study, the bistable character of the spin‐mode induced by reaction vessel diameter has been analyzed. First, a reactor with a discontinuously varying diameter for preliminary tests, and second, a conical reactor with a continuously varying diameter have been used. We have obtained evidence of bistability of the spin‐mode front in the frontal polymerization of trimethylopropane triacrylate under certain reaction conditions. Copyright © 2003 Society of Chemical Industry     

国内外己内酰胺生产现状及市场分析

世界上最大的5家己内酰胺生产商是德国BASF公司,生产能力为55.5万T/a;荷兰DSM公司,生产能力为42.0万t/a;美国Allied-Signal公司,生产能力为32.7万t/a;日本宇部兴产公司,生产能力为26.8万t/a;日本东丽公司,生产能力为17.0万t/a。这5家公司的已内酰胺生产能力合计为174万t/a,约占世界总产量的50％。中国目前有4套己内酰胺生产装置,岳阳巴陵鹰山石化厂,2000年生产能力为7万t/a;南京东方公司,生产能力为6万t/a;石家庄化纤公司,生产能力为5万t/a;浙江巨化公司锦纶厂,生产能力为0.45万t/a,全国合计年生产能力为18.45万t/a。国外己内酰胺的主要消费领域为纤维、工程塑料和食品包装膜;国内已内酰胺的主要消费领域为帘子布、民用丝、工程塑料,所占比例分别为70％、28％、2％。国内己内酰胺需求一直大于国内产量,但由于技术力量薄弱、资金有限及下游产品结构不合理等原因制约了己内酰胺的应用,目前国内的已内酰胺主要应用在中低档产品中,高档产品所需己内酰胺仍要依靠进口。     

An improved algorithm for diagnosis of system failures in the chemical process

The detailed techniques for improving the efficiency of a fault-diagnosis algorithm can be based on the signed directed graph. This graph represents the structure of the system, and the pattern on the graph represents a state of the system. The usefulness of the improved algorithm is demonstrated using a model of a chemical process comprising a reactor, a heat exchanger and a distillation tower.     

Splashing Characteristics of Monodisperse Sprays with Significant Viscosity Differences Impacting a Flat Surface

Drop impingement and splashing as a function of viscosity and, to a lesser extent, temperature are examined here. The working fluid is a mixture of water and glycerin with relative mass percentages varying from 0 to 100%, which spans a viscosity range of three orders of magnitude. First, a criterion that separates “on” and “off” for splashing as a function of glycerin percentage is expressed in terms of both Weber and Reynolds numbers and its highly nonlinear behavior is a function of the change in fluid viscosity. Next, the complex splashing characteristics of a rather simple monodisperse spray injected at a pressure of 2 bars onto a flat, 2-mm-diameter aluminum cylindrical rod are examined. Spatial variations in the fraction of splashed liquid, Sauter mean diameter, splashed droplet size distribution, and splash volume fraction as a function of radial distance for these mixtures are reported.     

Application of improved high-performance evaporator

An improved horizontal-tube, thin-film evaporator that has a high heat transfer coefficient when working at low temperature is described. Applying this evaporator, it is possible to design a multi-effect distiller with a very large number of effects and a vapour compression distiller with an extemely small compression ratio, thus achieving a considerble reduction in energy consumption in those processes.Actual applications of this improved evaporator are described as used in a conventional multi-effect distiller, a solar heated multi-effect distiller, a double-effect reheat type distiller and a mechanical vapour compression distiller. A notable point of this paper is the introduction of a new vapour compression distiller that has a lower energy consumption than ever seawater reverse osmosis desalination plant.     

Monitoring the oxidative modification of lipoprotein(a) by capillary zone electrophoresis

Lipoprotein(a) [Lp(a)] is a recognized risk factor for atherosclerotic cardiovascular disease. It is made of a lipoprotein particle containing apoB100 linked by a single disulfide bridge to apolipoprotein(a), a glycosylated protein with a variable mass. Some authors suggest that oxidative modification could explain the contribution of Lp(a) in the development of atheromatous lesions in a comparable way to low‐density lipoproteins (LDL). Recently, the use of capillary electrophoresis to measure the variations in the relative electrophoretic mobility (REM) of LDL subjected to copper oxidation has been proposed. The aim of this work is to employ this method also to monitor the copper‐induced oxidative modification of Lp(a). Migration of Lp(a) was monitored by absorption at 200 nm in a 50 mmol/L tricine, 100 mmol/L methylglucamine, pH 9.7 run buffer. Contrary to the conventional slab gel methods, our procedure provides a rapid and reproducible means to measure the electrophoretic mobility of Lp(a) (migration time <10 min with a CV% <0.5).     

Further studies on the high-speed gel-spinning of ultra-high molecular weight polyethylene

Summary The high-speed spinning technique has been applied to very elastic solutions of ultra-high molecular weight polyethylene in paraffin oil in an attempt to produce a strong fiber in a one-step process. At a winding speed of 4000 m/min a fiber was produced with a tensile strength of 2.3 GPa, a Young's modulus of 46 GPa and a elongation at break of 6.5%. This fiber could not be hot drawn anymore. At a winding speed of only 1 m/min the same solution yielded after spinning and hot drawing a fiber with a tensile strength of 7.2 GPa.     

Generalized Orowan-Petch Plot for Brittle Fracture

The fracture of brittle solids is considered to be based on a defect configuration consisting of a stress concentrator, in our case a hemispherical pore, and a starter crack, in our case either a semicircular crack, a circular crack, or a circumferential crack. Computation of the stress field, application of the relevant weight functions, and an averaging scheme based on the assumption of a virtual crack increment provides stress intensity factors for all defect configurations considered. A normalization scheme yields a generalized version of the Orowan-Petch plot in the form of a normalized strength to normalized defect size relationship.     

Measurement of short-term changes in heart rate and in plasma concentrations of cortisol and catecholamine in a small marsupial

Using a chronically placed jugular catheter and a silver electrode, it was possible to monitor short-term changes in the plasma concentration of cortisol and catecholamine in the marsupial sugar glider (Petaurus breviceps) and to monitor both heart and respiration rates. Males judged to be low in the social hierarchy of a particular group were exposed to the whole-body odor of a dominant male from the same social group, a foreign dominant male, or a castrate male. While there was no evidence of a change in any of the physiological parameters when a male was exposed to either a castrate male or a female, a rapid increase occurred in heart rate and plasma concentrations of cortisol, glucose and catecholamine when the donor was a dominant male from the same or a different social group.     

Anti- and Prooxidant Properties of Carotenoids

Carotenoids can be effective singlet oxygen quenchers and inhibit free-radical induced lipid peroxidation. A remarkable property of β-carotene ( 1a ) is the change from an antioxidant to a prooxidant depending on oxygen pressure and concentration. In the present study a considerable number of carotenoids ( 1a , 2c , 2d , 2e , 3a , 4a , 5a , 6a , 7a , 8a , 8h , 8i , 8j , 9f , 10a , 11a , 12g ) was investigated using two independent approaches: 1. Comparison of their effects on inhibition of the free-radical oxidation of methyl linoleate, and 2. The direct study of the effect of oxygen partial pressure upon their rates of oxidation. It is shown that some carotenoids ( 7a , 8a ) are even more effective than the well-known compounds β-carotene ( 1a ) and astaxanthin ( 5a ) and are powerful antioxidants without any prooxidative property. Different carotenoids display different behaviour depending on chain length and end groups. The influence of these functional groups on the antioxidative reactivity is discussed.     

Effect of the mechanical failure of catalyst pellets on the pressure drop of a reactor

The effect of the mechanical failure of catalyst pellets on the pressure drop across a laboratory-scale catalyst packing has been examined by experiment. Results reveal that, along with the mechanical failure of the pellets, there exists a point of maximum curvature around which the slope of pressure drop increases rapidly. This rapid increase is attributed to a mutation of the packing structure, occurring as the amount of failed pellets reaches a certain critical value. The secondary breakage of the pellets contributes much to the mutation of the packing and to the pressure drop. It has been observed that a trilobite catalyst is more susceptible to a mechanical stress than a cylindrical catalyst, and that a catalyst with a smaller diameter is much easier to result in an increase in the pressure drop. The measurement of the pressure drop across a laboratory-scale catalyst packing as the failure of pellets under a mechanical stress has a satisfactory reproducibility, and has a close meaning to the mechanical reliability of a fixed bed converter, and hence is recommended as a method for catalyst assessment. The multi-scale and multi-disciplinary nature of catalyst mechanical reliability is also discussed.     

The Effect of Interfacial Tension on the Adhesion of Cathodic E-coat to Aluminum Alloys

Adhesion of a cathodically electrodeposited paint (E-coat) to aluminum alloys, Alclad 2024-T3, AA 2024-T3 and AA 7075-T6, was investigated to examine the influence of interfacial tension at the paint/metal interface. The surface energy of an aluminum plate was modified by depositing a plasma polymer of a mixture of trimethyl silane (TMS) and one of three diatomic gases (O₂, N₂, and H₂) by cathodic plasma polymerization. The contact angle (Φ) of water on a modified surface changes as a function of the mole fraction of the diatomic gas. The plot of cos Φ_PP of a plasma polymer as a function of the mole fraction of the gas crosses the plot of cosΦ_EC of the E-coat. The difference, ΔCosΦ = cos Φ_PP - cosΦ_EC, is a parameter which indicates the level of interfacial tension at the paint/metal interface. ΔCosΦ = 0 represents the minimum interfacial tension. The adhesion of a cured E-coat on a panel was evaluated by the N-methyl pyrrolidinone (NMP) paint delamination time test. The maximum peak of adhesion test values plotted as a function of ΔCosΦ occurred around the zero point. ΔCos Φ = 0, indicating that maximum adhesion is obtained with minimum interfacial tension. Mixtures of TMS and N₂ on all three aluminum alloys studied consistently displayed longer delamination times in the NMP test than mixtures of TMS and O₂ or H₂.