真空冷冻干燥技术在食用菌加工中的应用研究

简析了食用菌冻干制品产业发展形势,概述了真空冷冻干燥技术原理及产品特点,阐述了应用真空冷冻干燥技术加工食用菌制品所需的主要设备、生产工艺流程及操作要点。探讨真空冷冻干燥过程中,各项工艺参数对食用菌干燥特性的影响。介绍食用菌冷冻干燥技术的优越性、技术壁垒及发展前景,旨在为采用真空冷冻干燥技术对食用菌进行干燥加工提供参考。     

野生刺梨与甜橙苹果南瓜复合清汁的研制

本文对野生刺梨与甜橙、苹果和南瓜为原料加工而成的复合澄清汁 (饮料 )工艺及其产品质量控制进行了研究 ,所研制的产品达到了预期目标。本工艺对野生刺梨的进一步开发利用有一定促进作用     

辛香蔬菜冻干工艺研究

本文研究了三种辛香蔬菜的真空冷冻干燥工艺,得到其冻干曲线,测定了三种蔬菜的共晶点,找到了比较适宜的物料铺放厚度和前处理方式以及干燥速率。根据本研究工艺真空冷冻干燥辛香蔬菜,较好的保持了辛香蔬菜的品质。     

真空冷冻干燥微生物的研究进展

真空冷冻干燥法是保藏微生物的最有效的方法之一 ,为提高真空冷冻干燥后微生物细胞的成活率人们已进行了大量的研究。综述了真空冷冻干燥方法的原理、应用及提高真空冷冻干燥后微生物细胞成活率的方法。     

真空冷却干燥微生物的研究进展

真空冷冻干燥法是保藏微生物的最有效的方法之一,为提高真空冷却干燥后微生物细胞的成活率人们已进行了大量的研究。综述了真空冷冻干燥方法的原理、应用及提高真空冷冻干燥后微生物细胞成活率的方法。     

响应面优化超声辅助提取刺梨多糖工艺研究

探讨超声波作用下刺梨多糖提取的最佳工艺条件。在单因素试验基础上,采用响应面法对刺梨多糖提取工艺参数进行优化研究。响应面试验表明提取温度、超声功率、超声时间、液料比对响应值刺梨多糖提取率均有显著影响,优化得到超声辅助提取刺梨多糖最佳工艺条件为:超声时间30 min,超声功率120 W,液料比40m L/g,提取温度80℃,提取3次。在此条件下的刺梨多糖提取率可达2.18%,与模型预测值非常接近。     

真空冷冻干燥技术在生物制药方面的应用

伴随着我国生物技术的迅速发展,真空冷冻干燥技术在生物制药行业的应用也越来越广泛。相对于传统的干燥技术,真空冷冻干燥技术更适合用于生物制品的生产加工。本文中将会介绍真空冷冻干燥技术的发展过程,冷冻干燥设备的原理,工艺流程以及注意事项,并总结了真空冷冻干燥技术应用于生物制药方面的优点。     

壶瓶枣干燥预处理及提取工艺对其多糖得率的影响

本文考察了不同的干燥预处理手段(烘箱干燥和真空冷冻干燥)及减压内部沸腾法中各因素(真空度、温度、液料比和提取时间等)对壶瓶枣多糖及蛋白质得率的影响。实验结果表明:干燥方式对原料枣粉的色差和多糖、蛋白质含量均有显著影响,对含水量无明显影响;真空冷冻干燥所得的枣粉色差小、多糖含量高、蛋白质含量低,综合考虑,选用真空冷冻干燥作为原料预处理手段;减压内部沸腾法最佳工艺参数为体系内温度60℃,液料比50∶1(mL∶g),提取时间30 min,此时外界温度为71℃,真空度为80 kPa,此条件下多糖及蛋白质得率分别为26.05 mg/g和2.14 mg/g;与传统热浸提相比,有效物质多糖得率提高了16.66%。     

刺梨与菊花、草莓复合浑浊果汁饮料的加工工艺

采用刺梨、菊花、草莓等原料制成浑浊型天然复合饮料。本品主要利用了刺梨的营养成分、菊花的芳香、草莓的颜色 ,使产品具有营养丰富 ,芳香浓郁 ,色泽美观 ,风味独特等特点。通过正交试验 ,得出最优配方组合为刺梨源汁 18% ,草莓 8% ,白糖 11% ,菊花 2 % ,产品酸度为 0 .2 5 % ,同时确定了最佳生产工艺及技术参数     

不同干燥方法对林下参品质的影响

目的：通过研究林下参不同干燥方法的干燥过程和对林下参物理性质及其皂苷类成分的影响，为林下参提供适宜干燥方法。方法：采用热风干燥、微波干燥、真空冷冻干燥3种干燥方法，对林下参的干燥时间、外观性状、体积收缩率、主根和芦的直径和长度收缩率、表皮和粉末的色泽及内在成分（总皂苷和8种单体皂苷）含量等指标进行分析评价。结果：微波干燥耗时最短，其次为真空冷冻干燥和热风干燥；真空冷冻干燥对林下参的外形和粉末色泽影响小，并且与热风干燥林下参的外观性状和微波干燥林下参的粉末色泽区别明显；真空冷冻干燥林下参和微波干燥林下参的体积、主根长和直径、芦长的收缩率小于热风干燥林下参，具显著差异；真空冷冻干燥林下参的表皮色差增长率最小；总皂苷含量、人参单体皂苷含量加和值、人参二醇型皂苷和人参三醇型皂苷含量的均值大小顺序为真空冷冻干燥林下参>微波干燥林下参>热风干燥林下参。结论：真空冷冻干燥较好的保留了林下参的形态和色泽，且真空冷冻干燥林下参人参皂苷含量高，真空冷冻干燥林下参具高附加值，综合考虑，真空冷冻干燥可以作为生产高档商品林下参的干燥方法。     

Strong paleoclimatic legacies in current plant functional diversity patterns across Europe

Numerous studies indicate that environmental changes during the late Quaternary have elicited long‐term disequilibria between species diversity and environment. Despite its importance for ecosystem functioning, the importance of historical environmental conditions as determinants of FD (functional diversity) remains largely unstudied. We quantified the geographic distributions of plant FD (richness and dispersion) across Europe using distribution and functional trait information for 2702 plant species. We then compared the importance of historical and contemporary factors to determine the relevance of past conditions as predictors of current plant FD in Europe. For this, we compared the strength of the relationships between FD with temperature and precipitation stability since the LGM (Last Glacial Maximum), accessibility to LGM refugia, and contemporary environmental conditions (climate, productivity, soil, topography, and land use). Functional richness and dispersion exhibited geographic patterns with strong associations to the environmental history of the region. The effect size of accessibility to LGM refugia and climate stability since the LGM was comparable to that of the contemporary predictors. Both functional richness and dispersion increased with temperature stability since the LGM and accessibility to LGM refugia. Functional richness' geographic pattern was primarily associated with accessibility to LGM refugia growing degree‐days, land use heterogeneity, diversity of soil types, and absolute minimum winter temperature. Functional dispersion's geographic pattern was primarily associated with accessibility to LGM refugia growing degree‐days and absolute minimum winter temperature. The high explained variance and model support of historical predictors are consistent with the idea that long‐term variability in environmental conditions supplements contemporary factors in shaping FD patterns at continental scales. Given the importance of FD for ecosystem functioning, future climate change may elicit not just short‐term shifts in ecosystem functioning, but also long‐term functional disequilibria.     

Computer modeling of deployment and mechanical expansion of neurovascular flow diverter in patient-specific intracranial aneurysms

Flow diverter (FD) is an emerging neurovascular device based on self-expandable braided stent for treating intracranial aneurysms. Variability in FD outcome has underscored a need for investigating the hemodynamic effect of fully deployed FD in patient-specific aneurysms. Image-based computational fluid dynamics, which can provide important hemodynamic insight, requires accurate representation of FD in deployed states. We developed a finite element analysis (FEA) based workflow for simulating mechanical deployment of FD in patient-specific aneurysms. We constructed FD models of interlaced wires emulating the Pipeline Embolization Device, using 3D finite beam elements to account for interactions between stent strands, and between the stent and other components. The FEA analysis encompasses all steps that affect the final deployed configuration including stent crimping, delivery and expansion. Besides the stent, modeling also includes key components of the FD delivery system such as microcatheter, pusher, and distal coil. Coordinated maneuver of these components allowed the workflow to mimic clinical operation of FD deployment and to explore clinical strategies. The workflow was applied to two patient-specific aneurysms. Parametric study indicated consistency of the deployment result against different friction conditions, but excessive intra-stent friction should be avoided. This study demonstrates for the first time mechanical modeling of braided FD stent deployment in cerebral vasculature to produce realistic deployed configuration, thus paving the way for accurate CFD analysis of flow diverters for reliable prediction and optimization of treatment outcome.     

A 19F-NMR study of 3-fluoro-4-demethoxydaunomycin intercalation complexes with the hexanucleotide d(CTGCAG)2

Equilibrium systems containing intercalation complexes formed between the novel anthracycline drug, 3-fluoro-4-demethoxydaunomycin (3FD), and the hexanucleotide duplex d(CTGCAG)2 have been studied by 19F-NMR spectroscopy. Solutions containing a 1:1 molar ratio of 3FD/d(CTGCAG)2 gave four 19F signals which have been assigned to each of four possible intercalation isomers for the 1:1 3FD.d(CTGCAG)2 complex, which we denote by [d(CTGCAG)2][3FD]; these were where 3FD bound between the 5'-CT-3', 5'-TG-3', 5'-GC-3' or 5'-CA-3' base sequences, with the drug sugar moiety lying in the minor groove and pointed in the 3' direction in each case. Changes in temperature and NaCl concentration affecting the equilibrium distribution of these isomers were studied and indicated that no overriding binding site preference prevailed under standard biochemical conditions. Formation of some of the 2:1 3FD.d(CTGCAG)2 complex occurred when a solution of [d(CTGCAG)2][3FD] was exposed to excess 3FD; however, this complex was unstable to gel filtration and no co-operative binding of the second 3FD molecule was observed.     

Apparent endocytosis of fluorescein isothiocyanate-conjugated dextran by Saccharomyces cerevisiae reflects uptake of low molecular weight impurities, not dextran

Concurrent with Riezman's report (Riezman, H. 1985, Cell. 40:1001-1009) that fluid-phase endocytosis of the small molecule Lucifer yellow occurs in the yeast Saccharomyces cerevisiae, Makarow (Makarow, M. 1985. EMBO [Eur. Mol. Biol. Organ.] J. 4:1861-1866) reported the endocytotic uptake of 70-kD FITC-dextran (FD) and its subsequent compartmentation into the yeast vacuole. Samples of FD synthesized and purified here failed to label yeast vacuoles under conditions that allowed labeling using commercial FD. Chromatography revealed that the commercial FD was heavily contaminated with at least three low molecular weight fluorescent compounds. Dialysis was ineffective for removing the contaminants. After purification (Sephadex G25, ethanol extraction), commercial FD was incapable of labeling vacuoles. Extracts of cells labeled with partially purified FD contained FITC, not FD, based on Sephadex and thin layer chromatography. In either the presence or absence of unlabeled 70-kD dextran, authentic FITC (10 micrograms/ml) was an effective labeling agent for vacuoles. The rapid kinetics (0.28 pmol/min per 10(6) cells at pH 5.5) and the pH dependence of FITC uptake suggest that the mechanism of FITC uptake involves diffusion rather than endocytosis. In view of these results, labeling experiments that use unpurified commercial FD should be interpreted with caution.     

Difficulty of obtaining reproducibility in the Franklin and Dukes test for the detection of sperm-agglutinating antibodies in human sera.

The Franklin and Dukes (FD) test is used as a screening test for the determination of sperm-agglutinating antibodies and as a proof of therapeutic effects in cases of infertility, but various parameters of the FD test remain unclear and the application of different techniques has revealed highly different results. To test the statistical evidence for the FD technique, conditions regarded as optimal prerequisites were applied: a sperm concentration of 20 times 10(6)/ml was produced with Baker's buffer and serum dilutions were made with Baker's buffer, starting at 1:4. Only the standard deviation of parallel tests with one serum sample and one semen sample on the same day was found to be within an acceptable range. Using ejaculates of the same donor and the same serum sample on different days gave results that were not reproducible. The FD test should not, therefore, be used for quantification of sperm-agglutination antibodies except for a comparison in one test with one semen sample on the same day. Although the FD test only allowed a qualitative evaluation of sperm-agglutinating antibodies the % sperm agglutination was more informative than agglutination titres. For quantification of sperm-agglutinating antibodies, the FD test should be replaced by other techniques.     

Cumulative frequency-dependent selective episodes allow for rapid morph cycles and rock-paper-scissors dynamics in species with overlapping generations

Rock-paper-scissors (RPS) dynamics, which maintain genetic polymorphisms over time through negative frequency-dependent (FD) selection, can evolve in short-lived species with no generational overlap, where they produce rapid morph frequency cycles. However, most species have overlapping generations and thus, rapid RPS dynamics are thought to require stronger FD selection, the existence of which yet needs to be proved. Here, we experimentally demonstrate that two cumulative selective episodes, FD sexual selection reinforced by FD selection on offspring survival, generate sufficiently strong selection to generate rapid morph frequency cycles in the European common lizard Zootoca vivipara, a multi-annual species with major generational overlap. These findings show that the conditions required for the evolution of RPS games are fulfilled by almost all species exhibiting genetic polymorphisms and suggest that RPS games may be responsible for the maintenance of genetic diversity in a wide range of species.     

Disentangling community functional components in a litter‐macrodetritivore model system reveals the predominance of the mass ratio hypothesis

Recent investigations have shown that two components of community trait composition are important for key ecosystem processes: (i) the community‐weighted mean trait value (CWM), related to the mass ratio hypothesis and dominant trait values in the community, and (ii) functional diversity (FD), related to the complementarity hypothesis and the divergence of trait values. However, no experiments controlling for the inherent dependence between CWM and FD have been conducted so far. We used a novel experimental framework to disentangle the unique and shared effects of CWM and FD in a leaf litter‐macrodetritivore model system. We manipulated isopod assemblages varying in species number, CWM and FD of litter consumption rate to test the relative contribution of these community parameters in the decomposition process. We showed that CWM, but also the combination of CWM and FD, is a main factor controlling litter decomposition. When we tested individual biodiversity components separately, CWM of litter consumption rate showed a significant effect on decomposition, while FD and species richness alone did not. Our study demonstrated that (i) trait composition rather than species diversity drives litter decomposition, (ii) dominant trait values in the community (CWM) play a chief role in driving ecosystem processes, corroborating the mass ratio hypothesis, and (iii) trait dissimilarity can contribute in modulating the overall biodiversity effects. Future challenge is to assess whether the generality of our finding, that is, that dominant trait values (CWM) predominate over trait dissimilarity (FD), holds for other ecosystem processes, environmental conditions and different spatial and temporal scales.     

High plant taxonomic beta diversity and functional and phylogenetic convergence between two Neotropical inselbergs

ABSTRACT

Background: Inselbergs (granitic and gneissic rock outcrops) are common elements in the Atlantic Forest and present large taxonomic (TD), functional (FD) and phylogenetic (PD) diversity.

Aims: We investigated how plant diversity changed across ecological and biogeographic scales by comparing TD, FD and PD of communities within and between two inselbergs. We expected converging FD and PD but distinct TD between outcrops, because of similar local environmental conditions in inselbergs and the long-term lineage isolation.

Methods: We calculated TD, PD and FD, and partitioned diversity into α (each inselberg), β (between inselbergs) and γ (whole sample) components. Phylogenetic signal was estimated for all traits. To link environmental predictors to functional traits a redundancy analysis was run. Variation in TD, FD and PD was analysed by general linear models with patch area and the two inselbergs as predictors.

Results: The inselbergs were taxonomically different, but showed convergence in their functional and phylogenetic diversity. The limited retention of phylogenetic signal suggests that different species may converge and respond similarly to environmental variables. Within inselbergs, larger patches displayed higher TD, FD and PD.

Conclusions: Seeking conservation strategies for inselbergs is challenging since, despite their functional and phylogenetic similarity, endemic species make individual rock outcrops unique.     

Properties of two types of calcium channels in clonal pituitary cells

The calcium currents of GH3 cells have been studied using the whole cell variant of the patch-clamp technique. Under conditions that eliminate sodium and potassium currents, we observed inward currents that activated within a few milliseconds, and deactivated with two time constants, approximately 150 microseconds and 3 ms at -80 mV, 18-20 degrees C. The components are called FD and SD (fast deactivating and slow deactivating). Both components are calcium currents, and are greatly reduced when magnesium is substituted for most of the calcium in the bath. In addition to (a) their different rates of deactivation, the two components differ in a number of other properties. (b) The SD component inactivates almost completely, with a time constant of 23 ms at 20 mV, 19 degrees C. The FD component, on the other hand, shows little or no sign of inactivation, and is almost the same in amplitude from 10 to 100 ms. The components thus seem quite independent of each other, and must arise from two independent sets of channels. (c) The FD channels activate more rapidly than SD at 20 mV, by a factor of approximately 2 as is shown in several ways. (d) In 10 Ca or 10 Ba, the activation curve for SD channels is approximately 20 mV more negative than for FD or Na channels. (e) FD channels conduct barium ions more effectively than calcium by a ratio of approximately 2. (f) FD channels "wash out" within minutes after the patch electrode breaks into a cell, whereas SD channel current remains relatively stable. It is argued that SD channels, because of their negative activation threshold, are involved in electrical events near threshold, and that FD channels are best suited for calcium injection once a spike has been initiated.     

Linear correlation between fractal dimension of EEG signal and handgrip force

Fractal dimension (FD) has been proved useful in quantifying the complexity of dynamical signals in biology and medicine. In this study, we measured FDs of human electroencephalographic (EEG) signals at different levels of handgrip forces. EEG signals were recorded from five major motor-related cortical areas in eight normal healthy subjects. FDs were calculated using three different methods. The three physiological periods of handgrip (command preparation, movement and holding periods) were analyzed and compared. The results showed that FDs of the EEG signals during the movement and holding periods increased linearly with handgrip force, whereas FD during the preparation period had no correlation with force. The results also demonstrated that one method (Katz’s) gave greater changes in FD, and thus, had more power in capturing the dynamic changes in the signal. The linear increase of FD, together with results from other EEG and neuroimaging studies, suggest that under normal conditions the brain recruits motor neurons at a linear progress when increasing the force.