不同补料发酵方式对发夫酵母产虾青素的影响

对发夫酵母的不同补料发酵方式进行了研究 ,期望提高发酵产率 ,以便对工业化生产提供一定的指导作用。实验结果表明 :采用恒pH葡萄糖 -氨水流加培养 ,色素量和生物量均具有最大值 ,分别为 5 4 .3μg ml和 4 9.5 μg ml;其次是指数流加培养 ,色素量和生物量分别为 4 9.9μg ml和 4 7.4mg ml;恒pO2 流加方式下色素量和生物量分别为 34.0 4ug ml和 35 .4mg ml;恒pH葡萄糖流加方式所得的色素量和生物量最小 ,分别为 32 .3μg ml和 31.5mg ml。不同的补料发酵方式对发夫酵母生长和色素形成的影响很大。

发夫酵母利用淀粉水解液发酵合成虾青素的研究

发夫酵母269菌株能够直接发酵玉米淀粉或马铃薯淀粉水解液进行虾青素的生物合成。淀粉水解液的主要成分为葡萄糖,另外还有少许二糖和极限糊精,在添加适量其它营养物质后,可被269菌株利用生产虾青素。摇瓶实验结果表明,培养72h后,发夫酵母的生物量为12.5g/l,虾青素的体积产率为11.86mg/l;在10L罐分批发酵实验中,72h后发夫酵母的生物量可达17.5g/l,色素的体积产率达19.5mg/l;在10L罐恒pH补料发酵实验中,128h后发夫酵母的生物量可达49.5g/l,色素的体积产率达54.3mg/l。

发夫酵母工业化生产虾青素的培养基研究

为进一步降低培养基成本,促进工业化生产,在前期优化的培养基基础上,本研究尝试直接以价廉易得的玉米粉、玉米淀粉、马铃薯淀粉水解液代替葡萄糖作碳源,进行摇瓶发酵实验和10 L罐分批发酵实验,探讨了发夫酵母产虾青素工业化培养基的制备。研究发现玉米淀粉水解液可代替葡萄糖作碳源进行工业化生产,并确定了淀粉双酶水解的最佳工艺条件为淀粉糊浓度为30%、液化酶添加量为25 U/g淀粉、糖化酶添加量为200 U/g淀粉、糖化时间为4 h。这样可大大降低培养基成本。

N维波发夫微分方程

将波发夫方程推广到了高维情形,得到了n维波发夫方程可解的充分必要条件;其次,研究了几类特殊波发夫方程通解的求法.

国内外虾青素的研究进展

介绍了虾青素不仅是一种粉红色的具抗氧化性的色素 ,而且生物学功能显著 ,可广泛应用于饲料、食品、医药和化工行业。对虾青素的来源 ,尤其是对产虾青素的发夫酵母的育种、工艺以及色素的提取等近年来在国内外的研究进展进行了论述。

齐次微分方程通解求法注记

对齐次微分方程的通解求法进行研究.利用齐次函数的特点,结合恰当方程求解的积分因子方法,得到了一类特殊齐次常微分方程通解的简便求法;其次,将齐次常微分方程和恰当方程推广到偏微分情形,得到了类似的结果.

Medium optimization to improve astaxanthin production of Xanthophyllomyces dendrorhous mutant W6-8 based on genetic algorithms

Genetic algorithms (GA) based on the principle of mimicing Darwinian evolution and survival of the fittest in a natural environment was used to optimize the medium for astaxanthin production by the mutant strain W6-8 of Xantho-phyllomyces dendrorhous. The 50 concentration levels of 6 medium components were optimized within 50 experiments (full experimental plan: 50^6 experiments). The results showed that GA could be applied in the medium optimization and better results were obtained. By employing optimized medium components (glucose 39.8 g l^-1, yeast extract 4.08 g l^-1,(NH4)2SO4 7.36 g l^-1, MgSO4 2 g l^-1, K2HPO4 2.04 g l^-1 and KH2PO4 3.48 g l^-1), the highest astaxanthin production was 9.855 mg l^-1, approximately 31% higher than that under the initial conditions, and was approximately 15.46% higher than that by orthogonal array but only slightly higher than that by response surface methodology. In the sequent scale-up experiments, the astaxanthin yield was obtained approximately 14.753 mg l^-1, employing the optimal medium. The results indicated that GA, as an euiicient method for medium optimization, was superior to other optimal means such as orthogonal array.

Studies on optimization of nitrogen sources for astaxanthin production by Phaffia rhodozyma

Fermentation of Phaffia rhodozyma is a major method for producing astaxanthin, an important pigment with industrial and pharmaceutical application. To improve astaxanthin productivity, single factor and mixture design experiments were used to investigate the effects of nitrogen source on Phaffia rhodozyma cultivation and astaxanthin production. Results of single factor experiments showed nitrogen source could significantly affect P. rhodozyma cultivation with respect to carbon source utilization, yeast growth and astaxanthin accumulation. Further studies of mixture design experiments using (NH4)2SO4, KNO3 and beef extract as nitrogen sources indicated that the proportion of three nitrogen sources was very important to astaxanthin production. Validation experiments showed that the optimal nitrogen source was composed of 0.28 g/L (NH4)2SO4, 0.49 g/L KNO3 and 1.19 g/L beef extract. The kinetic characteristics of batch cultivation were investigated in a 5-L pH-stat fermentor. The maximum amount of biomass and highest astaxanthin yield in terms of volume and in terms of biomass were 7.71 mg/L and 1.00 mg/g, respectively.

Efficient Extraction of Astaxanthin from Phaffia rhodozyma with Polar and Non-polar Solvents after Acid Washing

method of extracting astaxanthin from Phaffia rhodozyma with various solvents after acid washing was investigated. The extraction efficiency was distinctly increased after acid washing of P. rhodozyma cells. When the concentration of HCl was 0.4 mol.L^-1, the highest extraction efficiency of astaxanthin was achieved which was about three times higher than the control. Acetone or benzene as single polar or non-polar solvent was the most ef- fective solvent in our research. With a combination of isopropanol and n-hexane （volume ratio of 2 ： 1）, the maxi- mal extraction efficiency was achieved, approximately 60% higher than that obtained with a single solvent. The liquid-solid ratio and the extracting time were also optimized. Under the optimum extraction conditions, the extraction yield of astaxanthin exceeded 98%.

Embryology of Maldives Clownfish, Amphiprion nigripes (Amphiprioninae)

This study investigated the embryonic development of Maldives clownfish Amphiprion nigripes under natural conditions (28 - 30℃) at a lagoon of Agatti Island, Lakshadweep, India. The newly deposited fish egg was capsule-shaped and orange-red, with a (0.73 ± 0.04) mm3 yolk containing 5 - 10 fat globules. The embryonic development of fertilized eggs was divided into 26 stages and the time elapsing for each stage was recorded. Results showed that the cleavage was rapid, with the first division observed 1 h 20 min after fertilization. Blastulation occurred 4 h later, followed by gastrulation 12 h after fertilization, with a yolk volume of (0.61 ± 0.06) mm3. The organogenesis process started 22 h after fertilization when the blastopores closed and notochord formation began. The embryonic stage was recorded 24 h later, with the appearance of forebrain, midbrain, hindbrain, melanophores on yolk-sac and 22 somites, and a decreased yolk volume of (0.54 ± 0.08) mm3. Other organs developed well 31 h after fertilization, whereas the heart started beating and blood circulation began 78 h later. Red pigmentation (erytrophores) appeared 96 h after fertilization, with a small yolk volume of (0.22 ± 0.02) mm3. Mouth developed well and eyes were noticeable 120 h later, with head, pectoral fin and tail frequently moving 144 h after fertilization. The embryo reached the pre-hatching stage 168 h later and started to hatch after 170 - 180 h incubation. This study first detailed the embryonic development and yolk absorption of A. nigripes under natural conditions.

SPATIAL-TEMPORAL DYNAMICS OF REGIONAL CONVERGENCE AT COUNTY LEVEL IN JIANGSU

The dynamics of regional convergence include spatial and temporal dimensions. Spatial Markov chain can be used to explore how regions evolve by considering both individual regions and their geographic neighbors. Based on per capita GDP data set of 77 counties from 1978 to 2000, this paper attempts to investigate the spatial-temporal dynamics of regional convergence in Jiangsu. First, traditional Markov matrix for five per capita GDP classes is constructed for later comparison. Moreover, each region’s spatial lag is derived by averaging all its neighbors’ per capita GDP data. Conditioning on per capita GDP class of its spatial lag at the beginning of each year, spatial Markov transition probabilities of each region are calculated accordingly. Quantitatively, for a poor region, the probability of moving upward is 3.3% if it is surrounded by its poor neighbors, and even increases to 18.4% if it is surrounded by its rich neighbors, but it goes down to 6.2% on average if ignoring regional context. For a rich region, the probability of moving down ward is 1.2% if it is surrounded by its rich neighbors, but increases to 3.0% if it is surrounded by its poor neighbors, and averages 1.5% irrespective of regional context. Spatial analysis of regional GDP class transitions indicates those 10 upward moves of both regions and their neighbors are unexceptionally located in the southern Jiangsu, while downward moves of regions or their neighbors are almost in the northern Jiangsu. These empirical results provide a spatial explanation to the "convergence clubs" detected by traditional Markov chain.

老夫聊发少年狂

秋时长出了翅膀， 了却一个普游天下的愿望， 返老还童般披挂上阵。 叱咤风云般游山玩水欣赏风光。

老夫聊发少年狂

三国时魏文帝曹丕《九日与钟繇书》曰:"岁往月来,忽复九月九日。九为阳数,而日月并应,俗嘉其名,以为宜于长久,故以享宴高会。"十月,我们将迎来九九重阳老人节。 "网络新生活"栏目特意策划了老人上网的专题,作为献给老人们的一份礼物。21世纪是个性时代,是信息化时代,是网络时代,但并非仅仅属于年轻人的时代。从专题的几篇文章中,我们可以看到年过七旬还学习电脑、学习上网的老人的经历,更可以了解老人学习电脑的一些技巧,还可以得知晚辈如何帮助老年人学习上网,并且给他们带来了怎样的快乐。

Influence of genes,sex,age and environment on the onset of autoimmune hepatitis

The pathogenesis of autoimmune hepatitis (AIH) is complex. However,it is believed that a susceptible individual,owing to his genetic background,sex and age,can develop the disease following exposure to an environmental trigger. Autoimmune hepatitis does not follow a Mendelian pattern of inheritance; hence no single causative genetic locus has been identified. However,several genes,inside and outside the HLA locus,have been linked to an increased susceptibility to AIH. Epidemiological evidence also suggests that the sex and age of the patient plays a role in AIH pathogenesis as the disease onset occurs mainly in the two first decades of life and a higher disease incidence is observed in females. No environmental trigger has been identified,but several have been proposed,mainly viruses and xenobiotics. This article aims at reviewing the current knowledge on susceptibility factors leading to AIH and putative triggers,emphasizing fundamental mechanisms responsible for the break of liver immunological tolerance.

Agrobacterium-mediated transformation of herbicide resistance in creeping bentgrass and colonial bentgrass

Embryogenic calli were induced from the seeds of creeping bentgrass ( Agrostis palustris Huds.) cv. Regent and colonial bentgrass ( Agrostis Tenuis Sibth. Fl. Oxen.) cv. Tiger. The embryogenic calli were precultured on fresh medium for 4-7 days and then co cultivated with Agrobacterium tumefaciens , LBA4404, which contains plasmid vector pSBGM harboring bar coding region, synthetic green fluorescent protein (sGFP) coding region and matrix attachment region (MAR). After 3 days of co cultivation, the calli were washed thoroughly and transferred to MS medium containing 2 mg/L of 2, 4 D, 12-15 mg/L phosphinothricin (PPT) and 250 mg/L of cefotaxime. After 2-3 months of selection, the actively growing calli of 'Regent' and 'Tiger' were transferred to MS medium with 12-15 mg/L PPT and 250 mg/L cefotaxime for regeneration. The putative transformants were maintained on MS medium with 3 mg/L PPT for long period but control died within 1 month. After establishing in greenhouse, the transformants also showed strong resistance to 0.4% of herbicide Basta but control plants died within 2 weeks. Under confocal microscope, both young leaves and roots showed significant GFP expression. PCR analysis revealed the presence of a DNA fragment of GFP gene at the expected size (380 bp) in the transformants and its absence in a randomly selected control plant.

Internal Variable Formulations of Static and Dynamic Elastic-Plastic Problems Using Liapunov Functions： Algorithmic Aspects

The fundamental problem of an elastic-plastic body subjected to incremental loading is reviewed using a compact internal variable approach based on work carried out at the University of Cape Town in which a quadratic functional was developed for the free energy using Taylor series. Now the departure from that approach is the focus on developing the Liapunov function for the nonlinear differential equations of motion. Static and dynamic equations of motion are derived and shown to meet the requirements of the Liapunov function. As a consequence, time integration parameters that are used in the discrete formulations are easily obtained based on the same requirements. The resulting generalized Newton-Raphson scheme is stable in the sense of Liapunov＇s direct method.

350 μm map of the Ophiuchus molecular cloud: core mass function

Stars are born in dense cores of molecular clouds. The core mass function （CMF）, which is the mass distribution of dense cores, is important for understanding the stellar initial mass function （IMF）. We obtained 350μm dust continuum data using the SHARC-II camera at the Caltech Submillimeter Observatory （CSO） telescope. A 350μm map covering 0.25 deg2 of the Ophiuchus molecular cloud was created by mosaicing 56 separate scans. The CSO telescope had an angular resolution of 9＂, corresponding to 1.2 ×103 AU at the distance of the Ophiuchus molecular cloud （131 pc）. The data was reduced using the Comprehensive Reduction Utility for SHARC-II （CRUSH）. The flux density map was analyzed using the GaussClumps algorithm, within which 75 cores has been identified. We used the Spitzer c2d catalogs to separate the cores into 63 starless cores and 12 protostellar cores. By locating Jeans instabilities, 55 prestellar cores （a subcategory of starless cores） were also identified. The excitation temperatures, which were derived from FCRAO 12CO data, help to improve the accuracy of the masses of the cores. We adopted a Monte Carlo approach to analyze the CMF with two types of functional forms; power law and log-normal. The whole and prestellar CMF are both well fitted by a log-normal distribution, with p = -1. 18 ±0.10, σ = 0.58 ± 0.05 and μ= 1.40 ＋ 0.10, σ= 0.50 ＋ 0.05 respectively. This finding suggests that turbulence influences the evolution of the Ophiuchus molecular cloud.

Nomogram to predict primary non-response to infliximab in patients with Crohn’s disease:a multicenter study

Background:Infliximab(IFX)is effective at inducing and maintaining clinical remission and mucosal healing in patients with Crohn’s disease(CD);however,9%–40%of patients do not respond to primary IFX treatment.This study aimed to construct and validate nomograms to predict IFX response in CD patients.Methods:A total of 343 patients diagnosed with CD who had received IFX induction from four tertiary centers between September 2008 and September 2019 were enrolled in this study and randomly classified into a training cohort(n=240)and a validation cohort(n=103).The primary outcome was primary non-response(PNR)and the secondary outcome was mucosal healing(MH).Nomograms were constructed from the training cohort using multivariate logistic regression.Performance of nomograms was evaluated by area under the receiver-operating characteristic curve(AUC)and calibration curve.The clinical usefulness of nomograms was evaluated by decision-curve analysis.Results:The nomogram for PNR was developed based on four independent predictors:age,C-reactive protein(CRP)at week 2,body mass index,and non-stricturing,non-penetrating behavior(B1).AUC was 0.77 in the training cohort and 0.76 in the validation cohort.The nomogram for MH included four independent factors:baseline Crohn’s Disease Endoscopic Index of Severity,CRP at week 2,B1,and disease duration.AUC was 0.79 and 0.72 in the training and validation cohorts,respectively.The two nomograms showed good calibration in both cohorts and were superior to single factors and an existing matrix model.The decision curve indicated the clinical usefulness of the PNR nomogram.Conclusions:We established and validated nomograms for the prediction of PNR to IFX and MH in CD patients.This graphical tool is easy to use and will assist physicians in therapeutic decision-making.

Spontaneous Excitation of an Accelerated Detector Interacting with a Massive Scalar Field and Unruh Effect

We study spontaneous excitation of both a static detector （modelled by a two-level atom） immersed in a thermal bath and a uniformly accelerated one in the Minkowski vacuum interacting with a real massive scalar field. Our results show that the mass of the scalar field manifests itself in the spontaneous excitation rate of the static detector in a thermal bath （and in vacuum） in the form of a selection rule for transitions among states of the detector. However, this selection rule disappears for the accelerated ones, demonstrating that an accelerated detector does not necessarily behave the same as an inertial one in a thermal bath. We lind the imprint left by the mass is the appearance of a grey-body factor in the spontaneous excitation and de-excitation rates, which maintains the detailed balance condition between them and thus ensures a thermal equilibrium at the Unruh temperature the same as that of the massless case. We also analyze quantitatively the effect of the mass on the rate of change of the detector＇s energy and find that when the mass is very small, it only induces a small negative correction. However, when it is very large, it then exponentially damps the rate, thus essentially forbidding any transitions among states of the detector.

大事日志

1960年2月29日—3月15日2月29日我第一批派往印度尼西亚接侨轮船抵返黄埔港,载回侨胞二千一百多人。缅甸开始举行民族院选举。亚非人民团结理事会书记处发表声明,谴责日美签订新的“安全条约”。美国复照古巴,同意就悬而未决问题恢复谈判,但要保留干涉古巴的自由。3月1日摩洛哥西南部阿加迪港发生猛烈地震,死伤达五六千人。巴拿马人民举行反对美国和争取恢复运河区主权的示威游行。3月2日亚非人民团结理事会书记处发表声明,(?)责帝国主义进行军备竞赛。中、朝、蒙、苏铁道和外贸代表会议自2月22日至今在伯力举行。3月3日范文同函日内瓦会议两位主席,要求制止美国干涉老(?)、破坏日内瓦协议的行为。