Optimization of Hydrolysis Conditions for the Production of Antioxidant Peptides from Fish Gelatin Using Response Surface Methodology

Abstract: Fish skin gelatin was hydrolyzed with papain to produce antioxidant peptides. Response surface methodology (RSM) was applied to optimize the hydrolysis conditions (including enzyme to substrate ratio [E/S], hydrolysis time, and temperature). The highest degree of hydrolysis (DH) (50.1 ± 1.1%) was obtained at an E/S of 2% at 56.8 °C, 2.11 h, and was not significantly different from the predicted values within a 95% confidence interval. The highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) (96.8 ± 0.9%) and 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS^•+) (9.80 ± 0.11 mM Trolox [6-hydroxy-2,5,7,8-tetramethychroman-2-carboxylic acid]) radical-scavenging activities of fish gelatin hydrolyzates were obtained at an E/S of 3% at 52.1 °C, 2.65 h, and both DPPH and ABTS^•+ radical-scavenging activities were not significantly different from the predicted values 97.3% and 9.86 mM Trolox within the 95% confidence interval. Therefore, RSM is an efficient way to optimize fish gelatin hydrolysation and the resultant hydrolyzates show promise as antioxidant peptides. Practical Application: There is a growing interest in the use of fish gelatin as an alternative to mammalian gelatin. One potential use is as a source of widely acceptable functional compounds. In this study, a search for antioxidant peptides from fish gelatin prepared by an enzymatic method has been successfully done. This suggests that this is a practical way to obtain bioactive peptides.     

微软WORD格式中的软件质量保证

“在廉价的甜味逐渐减弱消失后,就会倍偿长期持续的苦味。“高质量软件的生命周期成本只是低质量软件的生命周期成本的几分之一。在一些情况下,质量保证的软件对于使用该软件的客户意味着生命悠关。例如,飞行员读了令人误解的荧屏显示就有可能以付出他（她）以及乘客的生命作为代价。软件质量保证方法或过程必须标准化并用于确保软件产品的安全以及成本效果,软件质量保证应占项目总成本的6%。     

Toughness in synthetic and biological multilayered systems

Toughness in hard biological tissues is associated with fibrous or lamellar structures that deflect or stop growing cracks. In some cases, such as nacreous shell, protein interlayers absorb much of the crack energy. In other tissues, such as tooth enamel, the toughness derives from the mineral microstructure, and the small amount of residual protein apparently has little effect. There have been a number of efforts to make tough synthetic materials using layered structures. In this work, freeform fabrication has been used to make layered structures with a view to introducing similar toughness into brittle materials. Results are presented for epoxy-glass composites with glass fabric interlayers, porous alumina back-filled with aluminium metal, and layered glass-ceramic/silver materials.     

Quantitative study of concentration overload,peak asymmetry,and efficiency loss in micellar electrokinetic chromatography

An equation is derived for the velocity of a thin zone of specific analyte concentration in micellar electrokinetic chromatography. The velocity varies with analyte concentration, because micellar solubilization changes electrical conductivity, micellar electrophoretic mobility, and the partitioning of anabyte between mobile and micellar phases. Two studies based on a weakly and a strongly retained neutral analyte are made to test a limiting form of the equation in which the first two changes are ignored. In the first study, peak asymmetries are characterized and plate numbers are measured in two types of experiments: one of fixed surfactant concentration and variable analyte concentration and one of fixed analyte concentration and variable surfactant concentration. In the second study, the isotherm describing both experiment types is measured and interpreted by the Langmuir model to evaluate the velocity equation. The equation of continuity is solved numerically for the peak profiles governed by the velocity equation. In all but one case, a good agreement is found between theoretical and experimental peak asymmetries and plate numbers in both experiment types. An equation is derived for the relative change of analyte velocity caused by the Langmuir isotherm. The change depends on the relative migration time, micellar saturation, and retardation factor. The predicted velocity changes correlate well with peak asymmetries and efficiency losses.     

An Evaluation of Random Testing

Random testing of programs has usually (but not always) been viewed as a worst case of program testing. Testing strategies that take into account the program structure are generally preferred. Path testing is an often proposed ideal for structural testing. Path testing is treated here as an instance of partition testing, where by partition testing is meant any testing scheme which forces execution of at least one test case from each subset of a partition of the input domain. Simulation results are presented which suggest that random testing may often be more cost effective than partition testing schemes. Also, results of actual random testing experiments are presented which confirm the viability of random testing as a useful validation tool.     

Arbitrarily polarized slot radiators in bifurcated waveguide arrays

The feasibility of obtaining arbitrary polarization in both one- and two-dimensional arrays of slots in dual mode bifurcated Waveguides has been demonstrated. The radiating element consists of a pair of crossed slots in the sidewall of a bifurcated rectangular waveguide that couple to even and odd waveguide modes. One linear polarization is excited by the even or "sum" mode and the orthogonal linear polarization is excited by the odd or "difference" mode. By superposing the sum and difference modes in the proper amplitude and phase, any arbitrary polarization can be realized. A two-dimensional array consisting of eight waveguide linear arrays, ferrite phase shifters for scanning in the plane normal to the linear arrays, and a feed network for power distribution and polarization control was constructed. Good radiation performance for various polarizations was obtained. In the case of linear polarization, the cross polarization component was on the order of -25 dB and in the case of circular polarization, the axial ratio was on the order of 1 dB. The polarization was controlled with a ferrite phase shifter. Close-in sidelobes of better than 20 dB were obtained for all polarizations. The preceding performance characteristics were obtained over a scan range ofpm20degand over a 6 percent frequency band.     

Design of maximum thrust plug nozzles with variable inlet geometry

An optimization analysis is presented for axisymmetric plug nozzles with varible inlet geometry. The analysis is based on the governing gas dynamic relations for a rotational flow of a frozen or equilibrium gas mixture. The problem is formulated to maximize the axial thrust produced by the plug nozzle for a general isoperimetric constraint, such as constant nozzle length or constant nozzle surface area. The effects of base pressure and ambient pressure are included in the thrust expression to be maximized. The governing gas dynamic equations and the differential and integral constraints that the solution must satisfy are incorporated into the formulation by means of Lagrange multiples. The formalism of the calculus of variations is applied to the resulting functional to be maximized. The results of the optimization analysis are a set of partial differential equations for determining the Lagrange multipliers in the region of interest and a set of equations for determining the necessary boundary conditions for the solution. The complete set of equations for the gas dynamic properties and the Lagrange multipliers are system of first order, quasi-linear, non-homogeneous partial differential equations of the hyperbolic type, which can be treated by the method of charac- teristics. The characteristic and compatibility equations for the system are presented. A numerical solution procedure is presented to determine wether or not a given plug nozzle geometry is an optimal solution. An iteration technique is developed which systematically adjusts the plug nozzle geometry until the optimal solution is obtained. Selected parametric studies are presented. These studies illustrate the effect of the specific heat ratio, the design pressure ratio and the base pressure model on the thrust peformance and nozzle geometry of optimal, fixed length, plug nozzles.     

Nova Scotia moose mystery--a moose sickness related to cobalt- and vitamin B12 deficiency

A wasting, debilitating disease with uncertain aetiology affecting moose (Alces alces americana) in Eastern North America has been reported repeatedly ever since the 1910s. Despite the intensive studies during 1930-1960s the cause of the sickness could not be established. In the 1960s a parasitic nematode (Parelaphostrongylus tenuis) was reported as constituting a probable explanation for the sickness, although several clinical and pathological signs remained unexplained. In Sweden, a moose disease with similar signs, has been shown to be caused by molybdenosis resulting from a nutritional imbalance. The findings of this investigation were applied in Nova Scotia to determine trace element concentrations in tissues from indigenous moose. Co deficiency was found in about half of the cases and the investigation was complemented by determining the vitamin B12 level, which proved nutritional Co/vitamin B12 deficiency, further verified by an increased MMA (methylmalonic acid) level in plasma. Deficiencies were found mainly in the Tobeatic and Cape Breton Highland regions. No indications of molybdenosis or other trace element disturbances were found in Nova Scotia. Otherwise, extremely high Cd levels (148 mg Cd/kg kidney wet wt., maximum) were found, though probably not contributing to the moose sickness. The Cd burden of moose on mainland Nova Scotia was more than 50% higher than that of moose in Huntville and Alonquin (Ontario, Canada) and five- to six-fold is higher than the highest Cd levels found in Sweden. To counteract the bio-geochemical effects of Co deficiency in the moose environment, provision of Co-containing salt licks is suggested.     

Economic growth and energy consumption in the UK, 1700–1975

This paper attempts to trace the development of energy consumption in the UK during the process of industrialization. First a quantitative overview of the relationship between energy consumption and economic growth for the period 1700–1975 is presented. An examination of the factors affecting relations between economic growth and energy consumption is then presented. This is divided into two main periods: pre-1800 and 1800–1975. The discussion of pre-1800 energy consumption is mainly concerned with coal use, while a more detailed account is given of developments in the later period.     

Mesure du Débit d’Absorption Spécifique (das) des téléphones mobiles — contribution du projetcomobio à la normalisation internationale

Human exposure to electromagnetic fields emitted by mobile phones is characterised by the Specific Absorption Rate (sar). This value corresponds to therf power absorbed by unitary mass of the equivalent tissue. It represents the basic restriction used to define limit of human exposure torf electromagnetic fields. Academic and industrial labs have contributed through thecomobio project to define international standards for mobile phones certification.