用猪血生产混合氨基酸工艺中水解时间的研究

<正> 用蛋白质水解法生产混合氨基酸,水解时间是一个至关重要的问题。水解时间太短,水解不完全,含肽量高,水解时间过长,会引起许多氨基酸酌破坏,即降低了得率又浪费了能源。我们在用阴离子交换树脂法脱酸法,以猪血为源料生产混合氨基酸工艺扩大试验时,对干猪血块的水解时间与水解程度的关系透行了探索,实验的结果列于下表:     

鸭毛水解制备复合氨基酸新工艺的研究

采用正交试验方法,对鸭毛水解制备复合氨基酸工艺条件进行优选,试验结果表明,鸭毛水解的最佳工艺条件为：水解时间10小时,反应温度100℃,盐酸浓度为4摩尔/升。     

工业废羊毛酸解工艺条件选择

毛发蛋白盐酸水解提取胱氨酸时 ,温度、毛酸比、时间等因素影响到毛发蛋白的水解率和产品胱氨酸的总收率。通过正交试验法 ,进行了废羊毛酸解工艺参数的试验研究 ,确定了最佳酸解工艺参数为 :温度 1 0 5℃ ,毛酸比(W/V) 1∶1 .7,连续水解时间 7.0h。     

正交实验法优化碱水解栀子提取物制取京尼平苷酸的工艺

以栀子提取物为原料,利用正交实验设计方法优化其碱水解制取京尼平苷酸的工艺。以京尼平苷酸产率为评价指标,考察了水解温度、NaOH加入量、料液比和水解时间4个单因素,采用四因素三水平正交实验设计优选得出最佳水解工艺:水解温度为70℃、NaOH加入量为14.0 m L、料液比1∶30 g/m L、水解时间为10 min,京尼平苷酸产率为11.53%。水解后溶液经过一次活性炭静态吸附和解吸,京尼平苷酸的含量可达45.33%。     

酶法水解谷朊粉工艺研究

对谷蛋白肽酶法制备工艺进行了研究.利用蛋白酶Alcalase可获得较高的水解度,其较优的工艺如下:底物浓度10%,加酶量为底物的0.5%,pH为8.75,水解温度60 ℃,水解时间90 min.酶解后期,添加蛋白酶Umamizyme进行复合酶水解,其产物具有多肽含量高、风味协调等特点.     

盐酸催化水解槐角异黄酮的研究

利用盐酸甲醇溶液对槐角总异黄酮进行水解制备染料木黄酮。采用高效液相色谱法检测槐角异黄酮水解率。探讨水解时间、盐酸浓度和水解温度对异黄酮水解率的影响,并通过响应面法确定最佳水解条件。实验结果表明最佳水解条件为:水解时间3.8 h、盐酸浓度2.59 mol/L、水解温度78.5℃。在此工艺下,槐角异黄酮水解率达93.38%。     

由扩展青霉PF86产生脂肪酶催化油脂水解的研究

研究了由扩展青霉ＰＦ８６８产生脂肪酶催化水解三种油脂的影响因素与工艺条件,其中包括：水解时间、温度、ＰＨ、酶量、油水比及添加剂,并用气相色谱对产品脂肪酸进行了分析鉴定,初步分析其催化水解的脂肪酸的特异性。     

美洲大蠊多糖的水解工艺及其抗氧化活性研究

美洲大蠊因具有广泛的药理活性而受到研究者的青睐,但其多糖的水解工艺和抗氧化活性鲜见报道,研究采用响应面法对美洲大蠊多糖的水解条件进行优化,通过单因素实验确定水解时间、温度和三氟乙酸用量对美洲大蠊多糖水解的影响,以高效液相色谱图中单糖的总峰面积为响应值,结合响应面实验,确定美洲大蠊多糖的最佳水解条件:水解时间1h,水解温...     

鲜猪血加压水解制备复合氨基酸新工艺的研究

采用正交试验方法,对鲜猪血加压水解制取复合氨基酸工艺条件进行优选。试验结果表明,采用鲜猪血加压水解制取复合氨基酸与采用猪血粉常压水解相比,简化了生产工序,缩短水解时间８～１２小时,降低能耗２倍多,减少硫酸用量２～３倍,而产品质量稳定可靠。     

利用蚕蛹生产复合氨基酸营养物研究——Ⅲ 蚕蛹酸水解330树脂脱酸制备混合氨基酸研究

本文对蚕蛹酸水解用330树脂脱酸制混合氨基酸及酸水解时间进行了研究,得到的结果是:常压下适宜的酸解时间为22小时。330树脂脱酸法最高收得混合氨基酸达83.26%,具有工艺简单,生产周期短,成本低,收率高等优点。     

Development and diagnostic value evaluation of a nutrient medium for the yield and isolation of hemoculture

The effectiveness of the bacteriological study of the blood depends in many aspects on the quality of nutrient media. The currently approved nutrient media for the isolation and yield of hemocultures have low isolation rates and require prolonged time for the isolation of causative agents. A two-phase nutrient medium for the yield and isolation of hemoculture has been developed. This medium has been found to have advantages over the control "double medium" in sensitivity, yield effect, growth rate and isolation rate with respect to the causative agents of bacteriemia and sepsis. The medium is standard and ready for use. The above-mentioned advantages of the medium increase the quality of the bacteriological diagnosis of bacteriemia and sepsis.     

黑龙港流域夏玉米产量提升限制因素

从产量构成因素及物质生产着手分析了黑龙港流域夏玉米产量进一步提高的限制因子.分析结果显示:穗数、穗粒数和千粒重均与产量显著相关,说明该地区夏玉米仍有继续增产的潜力;但在再高产过程中,单纯依靠穗数增加,产量增产幅度较小,应稳定在一定适宜的密度下,注重单位面积穗粒数和粒重的提高,但在穗数确定的情况下,穗粒数相对稳定,增加粒重成为再高产重要因素.因此,采取措施增强灌浆速率和延长灌浆时间是关键,即增强或稳定叶片在花后的有效光合能力.结果表明,增加叶片数量对产量贡献很小,而改善叶片质量、提高叶片功能,进而增加花后同化物合成至关重要.因此,茎秆和叶片的质量是再高产实现的关键技术突破点.同时,提高茎秆的花前物质转运比例也有助于提高于粒重,促进产量提升.在生产实践中,进一步挖掘产量必须搞清楚地上和地下两方面的关系,但目前对“根系-土壤”复合体的结构和功能研究相对较少.不合理耕作方式造成了土壤耕层太浅,严重影响了玉米根系生长发育,使生育后期吸收功能减弱,不利于产量形成.加之,吐丝前后阴雨寡照,造成穗粒数形成决定期的“源”不足,同时也限制了灌浆速率,提前播期,躲避灾害天气或推迟收获时期,延长灌浆时间等逆境栽培措施就显得尤为重要.     

Studies in the physiology of the onion plant; further experiments on the effects of storage temperature and other factors on onions grown from sets

A wide range of factorial experiments at Wisley on onions grown from sets included combinations of the factors: storage of sets at high and low temperatures during the winter, variety, set size, set planting date and nitrogen manuring. Bolting, yield and ripening data are recorded. One experiment was repeated in Scotland and Northumberland where early ripening was expected to be more important than at Wisley. In general, all the factors enumerated except nitrogen manuring had large effects on bolting and yield, and storage temperature had a large effect on the time of ripening. Varieties can be selected such that large sets may be used without appreciable loss by bolting and maximum yield thus secured. Storage temperatures of from 20 to 24° C., applied for about 14 weeks from October onwards, can be used to control bolting and to increase the yield even of non-bolting strains by delaying ripening and so extending the growth period. Storage at 24° C. is more effective in preventing bolting than the lower temperatures, but 20° C. is probably more effective in delaying ripening. High-temperature storage is probably unsuitable for sets to be planted in the north and west of Great Britain because of the difficulty of ripening the bulbs. For these districts low-bolting strains are therefore essential. Storage at o° C. gives only a partial control of bolting and has no effect on ripening. Late planting of sets, although very effective in controlling bolting, results in a substantial loss of yield and, therefore, is not a practical measure. Nitrogen manuring had practically no effect on yield and could not be used to prevent the loss of yield caused by late planting.     

Analysis of the physiological control of replication of ColE1-type plasmids

The physiology of ColE1-type plasmid replication in a growing host has been examined both theoretically, using computer simulation, and experimentally, by observing replication of the plasmid pBR322 after a nutritional shift-up from glycerol minimal medium (doubling time 71 min) to LB medium (doubling time 24 min). The theory was based on a negative control model and uses three rate equations: for the accumulation of cell mass, for the accumulation of the replication inhibitor, and for the rate of plasmid synthesis. The implications of the theory were explored by simulating the effects of changes in the expression of replication control genes. The nutritional shift-up experiment showed that plasmid replication was blocked immediately after the shift for about half a mass doubling time; after that time, replication rapidly increased until plasmid numbers per unit volume of culture parallelled the increase in culture mass. After the establishment of steady-state growth in the post-shift medium, the plasmid concentration (plasmids per cell mass) was reduced in comparison to pre-shift growth in the same proportion as the culture doubling time. The results showed that plasmid replication factors are under metabolic control and that the changes in the control of these factors compensate one another during steady-state growth, but not immediately after the medium shift.     

General characteristics of optimal feed rate profiles for various fed-batch fermentation processes

General Characteristics of the optimal feed rate profiles have been deduced for various fed-batch fermentation processes by analyzing singular controls and singular arcs. The optimal control sequences depend on the shapes of the specific growth and product formation rates, mu andpi, and the initial conditions. For fed-batch processes described by four mass balance equations, the most general optimal control sequence consists of a period of maximum feed rate, a period of minimum feed rate (a batch period), a period of singular feed rate (variable and intermediate), and a batch period. Degenerate sequences in which one or more periods are missing can result with a particular set of initial conditions. If the fermentation time is not critical, the singular control maximizes the net yield of product and only when the time is also important, it balances a trade off between the yield of product and the specific growth rate which dictates the fermentation time. With the sequence of optimal control known, the optimal feed rate profile determination is reduced to a problem of determining switching times.     

Death,demography and the denominator: Age-adjusted Influenza-18 mortality in Ireland

Using the Irish experience of the 1918–1919 Spanish flu pandemic (“Influenza-18”), we demonstrate how pandemic mortality statistics can be sensitive to the demographic composition of a country. We build a new spatially disaggregated population database for Ireland’s 32 counties for 1911–1920 with vital statistics on births, ageing, migration and deaths. Our principal contribution is to show why, and how, age-at-death data should be used to construct the age-standardised statistics necessary to make meaningful comparisons of mortality rates across time and space. We conclude that studies of the economic consequences of pandemics must better control for demographic factors if they are to yield useful policy-relevant insights. For example, while Northern Ireland had a higher crude death rate during the first wave of the Covid-19 pandemic, it also has an older population; age-adjusted mortality paints a very different picture.     

Effect of incorrectly estimated parameters on the control of specific growth rate inE. coli fed-batch fermentation

An exponential feeding strategy has been frequently used in fed-batch fermentation of recombinantE. coli. In this feeding scheme, growth yield and initial cell concentration, which can be erroneously determined, are needed to calculate the feed rate for controlling specific growth rate at the set point. The effect of the incorrect growth yield and initial cell concentration on the control of the specific growth rate was theoretically analyzed. Insignificance of the correctness of those parameters for the control of the specific growth rate was shown theoretically and experimentally.     

黄土丘陵沟壑区黄土坡面侵蚀过程及其影响因素

降雨强度、坡长、坡度是影响坡面产流产沙的重要因素。为定量分析降雨强度、坡长、坡度对黄土丘陵沟壑区安塞黄土坡面侵蚀过程的影响,本研究基于室内人工模拟降雨试验,分析2个坡长(5、10 m)、3个坡度(5°、10°、15°)、2个降雨强度(60、90 mm·h^-1)下安塞黄土坡面产流产沙规律。结果表明: 初始产流时间随坡长增加呈减小趋势,但总体变化不大;初始产流时间随降雨强度增加而减小,与60 mm·h^-1相比,90 mm·h^-1下缩短5.7～18 min;10°坡度上的径流起始时间最快。随降雨历时延长,产流率先快速增加,最终逐渐稳定在某一产流率值上下波动;产沙率在产流初期短时间内突然升高,达到最大值后减小,再逐渐达到稳定。产流率和产沙率随坡长和降雨强度的增加而增加,但随坡度变化规律不明显。随着降雨强度、坡长和坡度的增加,总产沙量相应增加。在降雨强度90 mm·h^-1时,坡长和坡度分别为10 m和15°的坡面产生了细沟,导致总侵蚀量最大(11885.66 g)。降雨强度为60 mm·h^-1时,随着坡长增加单位面积侵蚀量减小,在5～10 m坡段存在临界侵蚀坡长。坡长、坡度和降雨强度对坡面径流过程均有促进作用,降雨强度、坡长和两者之间交互作用对产流率和总侵蚀量的贡献率较大,其中,对产流率贡献最大的影响因素是降雨强度,贡献率为49.8%;坡长对总侵蚀的贡献率最大,为37.8%。     

大豆田银纹夜蛾系统控制研究

１９９３￣１９９６年以系统控制为基本技术原理,研究了豆田１１种可控因素对大豆银纹夜蛾,天敌和产量的综合效应,结果表明,对银纹夜蛾影响大的因素是种植方式,微肥,播期和钾素;对天敌影响最大的是种植方式;对大豆产量影响大的是种植方式;播期,品种和微肥。     

Temporal variation of the growth, carrageenan yield and quality of Kappaphycus alvarezii (Rhodophyta, Gigartinales) cultivated at Sepetiba bay, southeastern Brazilian coast

Kappaphycus alvarezii commercial cultivation is increasing along Brazilian coast. After 2008, more than 30 farms were established at Rio de Janeiro state in Sepetiba and Ilha Grande bays. Each farm has about ten floating rafts corresponding to near 900 m of cultivation line. Understanding the effect of the environmental factors on the growth and carrageenan yield and quality of the target algae in commercial farms will subsidize the establishment of efficient management activities to be used in the farms. In this sense, the temporal variation of the K. alvarezii daily growth rate, productivity, carrageenan yield, and quality (viscosity and gel strength) were analyzed using the seedlings cultivated in the largest Brazilian commercial cultivation at Sepetiba Bay. The daily growth rate, productivity, and carrageenan yield and quality were within the commercial requirement desirable for commercial crops. The main factors that caused the breakage of the floating rafts and consequently diminished the productivity are the storms. Water temperature and salinity were the other factors that influenced the daily growth rate and carrageenan yield and quality.