Lactic Acid Concentration and Microbial Spoilage in Anaerobically and Aerobically Stored Ground Beef

Lactic acid concentration of coarsely ground beef, packaged in low oxygen permeability casings, is inversely related to sensory acceptability of the meat following regrinding and aerobic storage for six additional days. Samples, reground and stored aerobically after periods of anaerobic storage, were assayed for total aerobic bacterial counts, percentage of gram-positive microflora, and pH. Lactic acid concentration ranged from 130 to 1055 mg per 100g ground beef and increased with anaerobic storage. During 6 days of aerobic storage, both increases and decreases in concentration were noted and related to changes in microbial flora. A positive correlation was found between the proportion of gram-positive bacteria (lactic acid bacteria) and lactic acid and pH.     

YTTRIUM ALUMINATE CERAMIC FIBERS VIA PRE-CERAMIC POLYMER AND SOL-GEL ROUTES

ABSTRACT

Yttrium aluminum garnet (YAG - Y₃Al₅O₁₂) fibers have been prepared by dry spinning solutions of yttrium and aluminum carboxylate polymers (precursor route) and by dry spinning aqueous oxide sols (sol-gel route). Fibers from aqueous diphasic gels are prepared by mixing a colloidal alumina sol containing 50-nm hydrous alumina with a colloidal yttria sol containing 10-nm yttrium oxide, using polyvinylpyrrolidone as a spinning aid. Fibers by the precursor route are made from spinnable THF solutions of yttrium isobutyrate and aluminum isobutyrate or from aqueous solutions of polymeric aluminum formate and yttrium acetate.

The isobutyrate materials decompose between 200-400^°C to an amorphous residue. Crystallization occurs abruptly between 875°C and 900^°C, forming the YAG phase directly. The formate-acetate also decomposes to amorphous residues, which form YAG at 900^°C. In the diphasic gel, YAG forms gradually between 1000 and 1200^°C, with intermediate products YAP (YalO₃ perovskite) and/or YAM (Y₄Al₂O₉ monoclinic). At 1500^°C, single phase YAG is obtained as pore-free fibers with 500 nm grains.     

花样美甲健康汇

伏笔:美甲成分也"毁"甲 很多喜欢美甲的女人多半会有这样的体验:刚做完美1甲1的指(趾)甲,真的是非常漂亮自已都忍不住时时端祥一下;可是过了段时间之后,想让自己的真指甲"透透气"时却发现,美甲,已经变成欲罢不能的事情——因为自已的真指甲已经变得"面目可憎,实在难以"维特形象",所以只能接着"美甲"否则,指甲就会有很长段时间都处在非常"丑陋"的状态,甚至病患丛生,让爱美的女人们难以接受.     

Master production scheduling,customer service and manufacturing flexibility in an assemble-to-order environment

A key element of manufacturing planning and control involves the inter-functional coordination of various manufacturing requirements. This paper reports the results of a simulation experiment that compares alternative master production scheduling (MPS) procedures in an assemble-to-order environment. The MPS procedures are superbills and covering sets. For a given investment in safety stocks the managerial problem is how to construct the MPS in order to minimize the firm's delivery time pressures. The results of the simulation experiment strongly support the use of the superbill techniques over the covering set technique. Moreover, of the experimental factors that influence delivery time performance, the choice of master production scheduling technique has the largest effect. Demand variability has the next greatest effect on delivery time performance. The safely stock level has the third greatest effect and product commonality was fourth. Finally, the managerial implications of the results are discussed in detail.     

Time-domain Array Analysis of Hybrid Systems Involving Coded Non-linearities†

The paper describes a numerical method using time-domain arrays for the analysis of discrete-continuous systems involving amplitude quantization, i.e. coded non-linearities. By the concept of generating matrices, systems of any order with synchronous or multi-rate samplers and involving multiple non-linearities may be analysed. The technique is particularly suited to digital computer implementation. An example of a saturating control system with error-amplitude quantization is considered.     

CHARACTERIZATION OF PAVING ASPHALTS BY DIFFERENTIAL SCANNING CALORIMETRY

ABSTRACT

Differential Scanning Calorimetry (D.S.C.) has been used to characterize the thermal behavior of various paving asphalts and their chromatographic fractions. In a single determination, several parameters, such as the glass transition temperature of the hydrocarbon matrix and the crystallized fractions, may be determined with good reproducibility. The glass transition is attributed to the aromatic and one part of the saturated fractions. The rest of the satured fraction has been found responsible for the endoihermal effect observed on warming which corresponds to the dissolution into the matrix. A method of determination of the crystallized fractions is described, and a comparison with the L.C.P.C. (Laboratoire Central des Ponts et Chaussdes - French Highway Administration Laboratory) method is made. The L.C.P.C. method was found to underestimate the real percentage of the crystallized fractions.     

Retention of volatile components during freeze drying of substances containing emulsified oils

Measurements have been made of the retention of a series of volatile acetates during freeze drying of sucrose solutions containing emulsified vegetable oils. The acetates partition to different extents between the oil and aqueous phases. The observed retentions can be interpreted in terms of a simple model whereby acetate located in oil droplets initially present in regions ultimately occupied by ice crystals are lost completely, whereas acetate in oil droplets present within residual concentrate are fully retained, and acetate in the aqueous phase is lost according to observations for initially homogeneous systems. As a general rule, only a small fraction of the oil droplets are present within the residual concentrate, and extraction of volatiles into an emulsified oil phase reduces volatiles retention during freeze drying.
The results and the model afford a rational interpretation of the results reported by Kayaert, Tobback & Maes (1974) for retention of individual aldehydes and mixtures of aldehydes during freeze drying of a model food system.     

COMPARISON OF ARTIFICIAL INTELLIGENCE METHODS FOR MODELING PHARMACEUTICAL QSARS

A common step in pharmaceutical development is the formation of a quantitative structure-activity relationship *(QSAR) to model an exploratory series of compounds. A QSAR generalizes how the structure (shape) of a compound relates to its biological activity. A comparative study was carried out of six artificial intelligence and traditional algorithms for modeling QSAR's: GOLEM, CART, and MS from symbolic machine learning; back-propagation from neural networks; and linear regression and nearest-neighbor from traditional statistics. Two test case problems were studied: the inhibition of Escherichia coli dihydrofolate reductase (DHFR) by pyrimidines, and the inhibition of ratlmouse tumor DHFR by triazines. It was found that there was no significant statistical difference between the methods in terms of their ability to rank unseen compounds by activity. However, symbolic machine learning methods, in particular relational ones, were found to generate rules that provided insight into the stereochemistry of compound receptor interactions.