On alternation

Summary Every alternating t(n)-time bounded multitape Turing machine can be simulated by an alternating t(n)-time bounded 1-tape Turing machine. Every nondeterministic t(n)-time bounded 1-tape Turing machine can be simulated by an alternating (n + (t(n)) ^1/2)-timebounded 1-tape Turing machine. For wellbehaved functions t(n) every nondeterministic t(n)-time bounded 1-tape Turing machine can be simulated by a deterministic ((nlogn)^1/2 + (t(n))^1/2)-tape bounded off-line Turing machine. These results improve or extend results by Chandra-Stockmeyer, Lipton-Tarjan and Paterson. A preliminary version of this paper was presented at the 19th IEEE-FOCS     

Polycyclic aromatic hydrocarbons (PAH) in various types of tea

For the analysis of the 16 PAH (EFSA-PAH), which are classified as priority for different food groups by the Scientific Committee on Food (SCF) and the Joint FAO/WHO Experts Committee on Food Additives (JECFA) in tea, a sensitive analytical Fast-GC/HRMS method was used. The sample preparation included accelerated solvent extraction (ASE) and the highly automated clean up steps, gel permeation chromatography and solid phase extraction. The analytical parameters, limit of detection (0.01–0.02 μg/kg) and limit of quantification (0.03–0.06 μg/kg), were determined. The repeatability (RSD, n = 3) of different PAH in fruit tea ranged from 0.1 to 11%. It was observed that the total contents of the 16 PAH in tea samples ranged from 14 to 2,662 μg/kg. The analysed tea samples showed an increasing presence of PAH in the following order: herbal and fruit tea (n = 7) < black tea (n = 11) < green tea (n = 11) < white tea (n = 3) < mate-tea (n = 8). The correlation coefficient (R) between BaP and the sum of the 16 EFSA-PAH was established considering the contamination amount in all the 40 tea samples analysed.     

Diamine oxidase supplementation improves symptoms in patients with histamine intolerance

Food Science and Biotechnology - Histamine intolerance (HIT) is thought to be caused by a disproportionate amount of histamine in the body. The enzyme diamine oxidase (DAO) is considered for the...     

Chemical composition,nutritive value and voluntary intake of tropical tree foliage and cocoyam in pigs

The composition of the leaves of cocoyam (Xanthosoma sagittifolium) and of two trees (Trichanthera gigantea and mulberry, Morus alba), their nutritive value in pigs and voluntary intake by pigs were determined. The average protein content ranged from 170 to 240 g kg^?1 dry matter (DM) and that of neutral detergent fibres from 218 to 398 g kg^?1 DM. The leaves are interesting sources of calcium (up to 69 g kg^?1 DM), potassium, iron and manganese. The proteins are well balanced in essential amino acids, with lysine ranging from 43 to 57 g kg^?1 proteins. The apparent faecal digestibility was determined by difference in 35 kg pigs fed a diet containing 35% leaf meal. The digestibility coefficients of DM, N and energy were, respectively, 47–57, 33–36 and 51–53%. The digestible energy value ranged from 1.674 to 2.037 kcal kg^?1 DM. The voluntary intake of Trichanthera and Xanthosoma was measured in sows weighing 100 kg on average. The intake reached 3.4 kg fresh leaves day^?1 (0.51 kg DM) and 1.0–1.1 kg dry leaf meal/day. It is concluded that low energy density is the main limiting factor of tree foliage for pig nutrition but that they are good sources of minerals and well‐balanced proteins. Copyright © 2005 Society of Chemical Industry     

Methods used for the isolation, enumeration, characterisation and identification of Enterococcus spp. 2. Pheno- and genotypic criteria

This paper reviews the methodology applied for the identification and characterisation of enterococci and covers phenotypic, genotypic and phylogenetic techniques. Although conventional phenotypic typing schemes are useful for rapid and simple identification of enterococcal species for routine applications, other methods like standardised sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE), multilocus enzyme electrophoresis (MLEE), antimicrobial susceptibility testing, serotyping, pyrolysis mass spectrometry (pyMS) and vibrational spectroscopic methods allow a more in-depth characterisation of enterococci. Many of the recently described enterococcal species exhibit deviations from hitherto so-called classical enterococci with regard to their phenotypical properties. Therefore, genotypic methods have to be used to clarify their possible assignment to the genus Enterococcus. In this review, special emphasis is given on recently developed polymerase chain reaction (PCR)-based typing methods such as random amplified polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP), specific and random amplification (SARA) and modifications of PCR-ribotyping as well as pulsed-field gel electrophoresis (PFGE) and partial sequence analysis. The use of PCR and probes for genus and species identification of enterococci is also considered like the application of sequence data of conserved DNA regions (e.g., ribosomal ribonucleic acid (rRNA) genes) in the case of species identification.     

小麦籽粒品质与馒头品质关系的研究

馒头是我国主要食品之一，消费量和面条相当，且南方的消费量还在逐年增长。21世纪以前，国内学者对制做馒头小麦粉品质的要求，馒头品质的评价方法，馒头品质与小麦品种籽粒品质的关系所能提供的研究资料十分有限。国外学者从70年代起就一直注意跟踪和研究这些问题。由于馒头的地域种类较多，不同人群对馒头的喜好不同，评价馒头品质指标的标准化程度不够，使不同结果之间有一定的差异，或完全相反。作者通过对小麦品种籽粒品质的分析，制作馒头面团发酵特性和油炸结果测定，馒头品质的评价认为：馒头对小麦粉品质的要求范围较大，从中筋到弱筋小麦品种都可以制作馒头；筋力愈高，面团的发酵时间愈长，馒头的弹性愈高；小麦品种小偃107制作的馒头色白，体积较大；小偃107的发酵面团在油炸过程中体积增加，有可能表现出吸油率低的特点。