Further studies on bovine muscle composition

The average occurrences of fibre types, I,IIA and IIB in the longissimus dorsi (LD) of female cattle were 18%, 59% and 23%, respectively. The IIB occurrence lay between that for bulls and steers, reported in Young & Bass (1984). Since IIB fibres were absent from the splenius (Sp) of females, its composition was more akin to that of bulls than steers. However, the relative area of I and IIA fibres in female Sp was more like that of steers than bulls since IIA fibres were not disproportionately large in females. Evidence suggests that the occurrence of type I (or II) fibres in the LD is rather static and that changes in the occurrence of IIA fibres, reciprocal to IIB, are more common, irrespective of sexual status-bull, steer or female. The route by which IIA and IIB fibres interconvert is discussed. In animals where both the LD and Sp were sampled, the fibre composition of one muscle was a poor predictor of the other's composition. The correlation between the occurrence of I fibres in Sp and succinate dehydrogenese activity in whole muscle was poor, and reasons are advanced to explain this unexpected result. When dark-cutting muscles were excluded from analysis, the average ultimate pH of LD muscles was lower than that of Sp. This result was consistent with the higher type II fibre content of the LD. Ultimate pH of Sp muscles was correlated with occurrence of I fibres, but in the LD a similar relationship could not be established. A link between occurrence of IIB fibres and proneness to the dark-cutting condition is suggested.     

Dufour Gland Contents of Ants of the Cataglyphis bicolor Group

The species of desert-dwelling ants of the Cataglyphis bicolor (Hymenoptera: Formicidae) group are difficult to distinguish by morphological features. Analysis of the secretion from the Dufour glands of workers of a number of colonies was undertaken to see if it provided a clear test of species. Linked 6c-ms showed in all samples straight and branched-chain alkanes, linear alkenes, ketones, aldehydes, acetates, and a group of C₂₂ to C₂₈ esters not previously identified in this genus. Contents of the Dufour glands of C. savignyi from Tunisia and Egypt were similar, and comprised straight and branched-chain alkanes, alkenes and small amounts of esters. C. bicolor from Tunisia contained compounds similar to C. savignyi but was distinguished from the latter by larger amounts of the esters. The major compound in the glands of C. viaticus was tridecane, in contrast to the pentadecane of other species. It also contained a branched alkane, 3-methyltridecane as a major component. Branched-chain esters and a wide variety of acetates were also found in this species. C. diehlii had a limited range of compounds, with branched alkanes almost completely absent and high proportions of pentadecene and dodecyl acetate. C. bombycinus, a sympatric species, but recognized as not belonging to the bicolor group by its different mandibular gland substances, was notable in having butanoate esters in its Dufour glands. Despite these differences among species, both the great variability of individuals from a single colony and the among between conspecific colonies make species diagnosis from a few individuals difficult, in contrast with postpharyngeal glands, which, as recently reported, give a clearer indication of species.     

Power spectrum and Allan variance methods for calibrating single-molecule video-tracking instruments

Single-molecule manipulation instruments, such as optical traps and magnetic tweezers, frequently use video tracking to measure the position of a force-generating probe. The instruments are calibrated by comparing the measured probe motion to a model of Brownian motion in a harmonic potential well; the results of calibration are estimates of the probe drag, α, and spring constant, κ. Here, we present both time- and frequency-domain methods to accurately and precisely extract α and κ from the probe trajectory. In the frequency domain, we discuss methods to estimate the power spectral density (PSD) from data (including windowing and blocking), and we derive an analytical formula for the PSD which accounts both for aliasing and the filtering intrinsic to video tracking. In the time domain, we focus on the Allan variance (AV): we present a theoretical equation for the AV relevant to typical single-molecule setups and discuss the optimal manner for computing the AV from experimental data using octave-sampled overlapping bins. We show that, when using maximum-likelihood methods to fit to the data, both the PSD and AV approaches can extract α and κ in an unbiased and low-error manner, though the AV approach is simpler and more robust.     

电脑鼠走迷宫算法仿真设计

主要研究电脑鼠走迷宫的算法,主要包括迷宫生成算法、原始全迷宫搜索算法和修正后的泛洪算法.改进后的算法可以搜索到从起点到终点的所有可行路径中的一条最佳路径,以实现快速、高效求解迷宫的目的.     

一种前向型神经网络基准地价预测模型的研究

土地是国家重要资产,对地价的全面监测、分析和预测,有助于城市基准地价的快速更新和政府对土地资源的宏观控制。现阶段基准地价水平调整的预测模型有明显的不足。应用一种非线性预测方法:多层前向神经网络建立基准地价预测模型,采用时间预测序列。在介绍误差反向修正算法的基础上,通过预测实例计算,表明预测结果与实际情况吻合较好     

Software sensor for on-line estimation of the microbial activity in activated sludge systems

This paper considers the design of a software sensor (or soft-sensor) for the on-line estimation of the biological activities of a colony of aerobic micro-organisms acting on activated sludge processes, where the carbonaceous waste degradation and nitrification processes are taken into account. These bioactivities are intimately related to the dissolved oxygen concentration. Two factors that affect the dynamics of the dissolved oxygen are the respiration rate or the oxygen uptake rate (OUR) and the oxygen transfer function (K(l)a). These items are challenging topics for the application of recursive identification due the nonlinear characteristic of the oxygen transfer function, and to the time-varying feature of the respiration rate. In this work, OUR and the oxygen transfer function are estimated through a software sensor, which is based on a modified version of the discrete extended Kalman filter. Numerical simulations are carried out in a predenitrifying activated sludge process benchmark and the obtained results demonstrate the applicability and efficiency of the proposed methodology, which should provide a valuable tool to supervise and control activated sludge processes.     

Polysaccharides as excipients for colon-specific coatings. Permeability and swelling properties of casted films

Oligosaccharides such as inulin (In) and polysaccharides such as galactomannans, combined with polymethacrylates on isolated films for film coatings, were obtained from aqueous-based solvents and investigated as potential vehicles for colonic drug delivery. These compositions, which are susceptible to fermentation by colonic microflora, constitute promising excipients for the development of new colon-specific therapeutic systems. The characteristics of several compositions have been demonstrated in permeability and swelling studies on isolated films composed of a polymethacrylate associated with In or galactomannans of mesquite seed gum (MSG). Results reported prove a dependency of the properties of mixed films on the polymethacrylate-polysaccharide concentration ratio and on the composition of the dissolution media. An increase in permeability through the mixed films was observed in a simulated colonic environment for the following compositions: Eudragit®RS30D-MSG 70 : 30 w/w; Eudragit® RS30D-In 90 : 10 w/w; Eudragit®RS30D-In 76 : 24 w/w.     

Compressional characteristics of native and pregelatinized forms of sorghum,plantain, and corn starches and the mechanical properties of their tablets

A study was made of the compressional characteristics of native and pregelatinized forms of sorghum, plantain, and corn starches and the mechanical properties of their tablets. Compressional characteristics were analyzed using density measurements and the Heckel and Kawakita plots. Pregelatinized starches exhibited more densification than native starches during die filling and at low pressures. The ranking for the mean yield pressure (Py) values for the starches was plantain < corn < sorghum, with the pregelatinized starches having lower values than the native starches. The ranking for the values of another pressure term, Pk--an inverse measure of plasticity, was corn < plantain < sorghum, but with the native starches having the lower values. For the tablets, the ranking for values of tensile strength (T) was corn > plantain > sorghum, while the ranking for the brittle fracture index (BFI) was plantain > corn > sorghum. Tablets made from pregelatinized starches had lower T and BFI values than those made from native starches. The results suggest that pregelatinization of the starches facilitated faster onset of plastic deformation but reduced the amount of plastic deformation which occurred during the compression process.     

A receptor-based bioassay for quantitative detection of gallium

The detection of gallium in biological samples is required due to its role in the diagnosis of tumor and for possible treatment of malignancies. However, the use of purely instrumental techniques is unsuitable for detection of low levels of gallium in biological matrixes. We have synthesized new protein conjugates based on 4-(2-pyridylazo) ligands. The conjugates were successfully employed for the detection of gallium in biological matrixes using a nonantibody-based sandwich assay format. The recovery level obtained was between 97 and 101.3 with a relative standard deviation of less than 5%. The assay resulted in a detection limit of 5 x 10(-8) M and a remarkable selectivity for gallium(III) relative to other metals investigated. The new method provided adequate accuracy for gallium applicable for animal physiology and clinical toxicology.     

用辅助燃料取代30%焦炭的高炉冶炼物料平衡和热平衡

用辅助燃料取代３０％焦炭的高炉冶炼物料平衡和热平衡［乌克兰］С．Л．Ярошевский等近年来采用煤粉燃料进行高炉冶炼的工艺在国外得到广泛应用。１９９２年世界上有２０个国家的近１００座高炉实现了喷煤，喷煤量为７０～２１０ｋｇ／ｔ铁不等，降低焦比达２...