Fate of minor free amino acids and phospholipids in crude tallow during steam splitting

Minor free amino acids and phospholipids contained in crude tallow were monitored during steam splitting of crude tallow. The bulk of the phospholipids was found in the glycerol sidestream after splitting. Phosphatidic acid and phosphatidylcholine were present in both crude tallow and the glycerol fraction. Phosphatidylserine and phosphatidylethanolamine present in crude tallow were hydrolized with the glycerides. Because of this hydrolysis, high amounts of serine and ethanolamine are found in the fatty acid and glycerol fractions. In addition to constituent amino acids of proteins present in crude tallow, other biological amino acids such as taurine and ornithine were also present.     

Fate of coal nitrogen during combustion

A total of 21 coals covering all ranks have been burned under a wide variety of conditions to ascertain the impact of coal properties on the fate of fuel nitrogen. Fuel NO was identified with a nitrogen-free oxidant consisting of Ar-O₂CO₂. In general, under fuel-lean conditions fuel NO formation increases with increasing fuel nitrogen content; however, other fuel properties also significantly affect the fate of fuel-bound nitrogen during combustion. In particular, fuel nitrogen conversion appears to be greater with coals containing a high fraction of volatile reactive nitrogen. Under fuel-rich conditions measurements of first-stage and exhaust-species concentrations suggest that the optimum stoichiometry for minimum emissions is a function of fuel composition. As first-stage stoichiometry is decreased, the NO formed in the first stage decreases, but other oxidizable gas nitrogen species increase as does nitrogen retention in the char. Total fixed nitrogen generally increases with increasing fuel nitrogen and correlates well with excess air exhaust emissions. The distribution of the total fixed nitrogen species leaving the first stage is strongly dependent upon the coal composition. Of the 12 coals tested in detail, only 1 (the high-volatile B bituminous from Utah) produced high HCN concentrations. The low-volatile Pennsylvania anthracite formed almost no HCN or NH₃ even under extremely fuel-rich conditions. In general, the first stage NO percentage decreased significantly with decreasing coal rank from anthracite to lignite. Conversely, the relative importance of NH₃ grew with decreasing rank. HCN was greater than NH₃ in all bituminous tests, but less than NH₃ with all subbituminous and lignite coals.     

Investigation of free radicals produced during coal liquefaction using ESR

Coal liquefaction experiments are described which were carried out to dissolve a subbituminous coal in low and high hydrogen content solvents, in which liquid samples were periodically withdrawn and examined by electron spin resonance spectroscopy. The objectives of this study were to gain information on the free radical processes involved in coal liquefaction, to determine the relative effectiveness of two solvents (H-donor and non-donor) in influencing the radical processes involved in coal liquefaction and to investigate changes in radical concentration on storage.     

氮源影响酵母耐受超高浓度乙醇发酵胁迫条件

为考察蛋白胨和酵母浸出膏对酵母耐受超高浓度乙醇发酵胁迫条件的影响,以300g/L起始浓度葡萄糖开展实验。结果表明,与对照组(3g/L蛋白胨+5g/L酵母浸出膏作为氮源)相比,单独提高发酵培养基蛋白胨至6g/L或酵母浸出膏至12g/L,均可明显促进菌体生长和葡萄糖利用,终点乙醇体积分数由对照组的13.1%分别提高至14.4%和14.7%。研究表明,在发酵过程中,生长于提高蛋白胨浓度或酵母浸出膏浓度培养基的菌体,其质膜ATP酶活力和胞内海藻糖积累量明显高于对照组,而且发酵参数(如菌体生长、葡萄糖利用和终点乙醇体积分数)的提高与酶活力和海藻糖含量的增加密切相关,提示质膜ATP酶和胞内海藻糖在酵母耐受超高浓度乙醇发酵胁迫条件中的作用。     

Lipids in the germ,endosperm and pericarp of the developing maize kernel

Acyl lipids were quantified in the germ, endosperm and pericarp of LG-11 maize kernels at eight stages of development from 9 to 87 days after pollination (DAP). Changes in the lipids are discussed in relation to morphological events in the developing kernel. Storage lipids (triglyceride, steryl ester) and membrane lipids (diacylphospholipids) accumulated in germ until 52-76 DAP, then decreased slightly without formation of lipid degradation products, lated in endosperm until 36-42 DAP and then decreased. Maximum values for galactosyldiglycerides and diacylphospholipids (nonstarch lipids) were reached at 16-23 DAP, and all decreased to very low values at maturity. Loss of these functional (membrane) lipids during the period of endosperm cell filling is unexpected. Starch contained 82% of the lysophospholipids and 64% of the free fatty acids in endosperm at 76 DAP. Endosperm lysophospholipids increased until 76 DAP and then decreased slightly, while free fatty acids increased continuously mostly inside starch granules at all stages of development, and any possible decrease after 76 DAP was masked by acids formed by hydrolysis of aleurone and endosperm nonstarch lipids from 52 DAP. In DAP, and phospholipids decreased after 42 DAP. Loss of these lipids is associated with senescence of most pericarp tissue. Triglycerides and steryl esters accumulated steadily to maturity, while the main accumulation of unsaponifiables occurred after 52 DAP about the time of suberin formation.     

乙醇连续发酵过程中自絮凝酵母颗粒粒径分布的模拟

以酿酒酵母和粟酒裂殖酵母的融合株——自絮凝颗粒酵母SPSC01为研究对象,选择搅拌式反应器为模式系统,利用聚焦光束反射测量仪（FBRM）在线检测了絮凝酵母颗粒的弦长频率分布.研究表明,在含有絮凝缓冲液的模拟系统中,自絮凝酵母颗粒粒径分布符合对数正态分布.粒径分布的特征参数（M）与搅拌转速（r）之间的关系可用对数方程表示,从而简化了絮凝酵母颗粒粒径分布的定量表征.在真实的乙醇连续发酵过程中,细胞代谢生成的CO₂对测量体系产生了干扰,利用建立的自絮凝酵母颗粒粒径分布的在线检测和定量表征方法,在数据处理过程中排除了这种干扰,得到了自絮凝酵母SPSC01絮凝颗粒的粒径分布.     

Morphological and metabolic changes in the yeast Kluyveromyces marxianus var. marxianus NRRLy2415 during fermentation of lactose

Oxygen availability has been identified as a major factor in governing the morphology of the lactose-fermenting yeast, Kluyveromyces marxianus var. marxianus (formerly fragilis) NRRLy2415. In this particular strain, filamentous cells (F forms) predominate during the initial stages of aerobic propagation whilst budding yeast cells (Y forms) predominate during anaerobiosis. In other K. marxianus strains, and in Candida pseudotropicalis, budding cells predominate irrespective of oxygen availability. Increased cellular cytochrome contents and oxygen uptake rates accompanied Y to F (yeast to filamentous) transitions in K. marxianus NRRLy2415, suggesting that functional mitochondria are involved in controlling dimorphism in this yeast. This was further supported by the observation that respiratory inhibitors such as chloramphenicol prevented filamentation and promoted formation of respiratory-deficient budding cells. During aerobic batch cultivation. K. marxianus displayed physiological variability in which cells were initially filamentous and respiratory but latterly were yeast-like and fermentative, suggesting that growth rate as well as oxygen availability affected cell physiology. This was supported by the finding that during growth in lactose-limited chemostat culture, the morphology and respiratory activity of K. marxianus varied with the specific growth rate of cells. I n addition, the fermentation rates of F and Y forms varied, although maximum ethanol yields were not significantly different between the two morphologies. These results have implications for the more eflcient conversion of lactose to ethanol in commercial fermentations of cheese whey.     

The distribution of lipids in the germ,endosperm, pericarp and tip cap of amylomaize,LG-11 hybrid maize and waxy maize

The quantitative distribution of 23 acyl lipid classes and unsaponifiable matter in kernels of amylomaize, LG-11 hybrid maize and waxy maize is described. LG-11 and waxy maize were normal (oil content) varieties, containing 4.9% and 5.1% lipid, respectively, while amylomaize (9.3% lipid) was a high oil variety. The distribution of kernel lipids was 76–83% in germ, 1–2% in pericarp, 1% in tip cap, 1–11% in starch, and 13–15% in aleurone plus the nonstarch fraction of the starchy endosperm. Germ contained 39–47% lipid, which was nostly triglyceride (TG), with some steryl esters (SE) and diglycerides (DG), and small amounts of glycolipids (GL) and phospholipids (PL). Aleurone lipids appeared to be TG with some free fatty acids (FFA) and SE. The other nonstarch lipids in starchy endosperm were FFA with very small amounts of SE, DG, GL and PL. The starches had a little surface lipid (FFA) and true (internal) starch lipid (FFA, lyso-PL) in quantities roughly related to amylose content (amylomaize =ca. 73% amylose, 1.0% lipid; LG-11=23% amylose, 0.7% lipid; waxy maize =<5% amylose, 0.2% lipid). Pericarp lipids (0.8–2.5%) were mainly unsaponifiable matter, the acyl lipids being TG, SE, DG and FFA. Tip cap lipids (2.5–2.9%) had more TG, GL and PL than pericarp lipids, but were otherwise similar. Pericarp lipids and endosperm nonstarch lipids appeared to have suffered extensive degradation at some time during kernel development or after harvesting, while lipids in starch, germ and tip cap were evidently unaffected. FFA and lyso-PL are regarded as normal components of maize starch (rather than degradation products) and may occur as amylose inclusion complexes.     

Kinetics of coal liquefaction during heating-up and isothermal stages

Direct liquefaction of Shenhua bituminous coal was carried out in a 500 ml autoclave with iron catalyst and coal liquefaction cycle-oil as solvent at initial hydrogen of 8.0 MPa, residence time of 0–90 min. To investigate the liquefaction kinetics, a model for heating-up and isothermal stages was developed to estimate the rate constants of both stages. In the model, the coal was divided into three parts, easy reactive part, hard reactive part and unreactive part, and four kinetic constants were used to describe the reaction mechanism. The results showed that the model is valid for both heating-up and isothermal stages of liquefaction perfectly. The rate-controlled process for coal liquefaction is the reaction of preasphaltene plus asphaltene (PAA) to oil plus gas (O + G). The upper-limiting conversion of isothermal stage was estimated by the kinetic calculation.     

Implementation and demonstration of a quasi-steady-state controller for yeast fermentation

Earlier work has presented the need for, and the structure of, a control system to force fed batch fermentations to a quasi-steady-state (QSS) rapidly. Necessary modifications to this controller to permit it to be implemented on a computer-coupled laboratory fermentor are presented. These include use of manual sampling to obtain reliable cell concentration data and the use of stream blending to achieve the desired control actions. The implementation is via a DDC loop structure which achieves proportional feedback control, calibrated decoupling of response models, and non-linear time-varying actuator constraints. The experimental run presented shows the desired rapid response of cell concentration with evidence of no interaction between cell and substrate, even though the manipulated variables are saturated throughout much of the transient.     

Fate of mercury and chlorine during SRF co-combustion

Within the scope of the European Demonstration project RECOFUEL the behaviour and fate of chlorine and mercury during co-combustion of Solid Recovered Fuel (SRF) was investigated in detail, focusing on the environmental compatibility, and based on a lab-scale approach. In this context the term co-combustion describes the thermal utilisation of pre-treated waste-derived fuels such as SRF in industrial furnaces or power plants as a supplemental fuel.Following the definitions of the European initiative on SRF standardisation CEN/TC 343, these kind of fuels have to be produced from non-hazardous bio-residues, mixed- and mono waste streams. It is one of the key aspects of the production process to reduce the content of waste-borne pollutants such as chlorine or heavy metals. Nonetheless, the efficiency of the production process is limited and the residual pollutant concentrations may exceed those of coal to a certain extent.The experiments, focusing both on chlorine and mercury, indicated that the co-combustion process increases the flue gas concentration of gaseous chlorine species, primarily hydrogen chloride, as a result of waste-borne chlorine. Furthermore, significant differences were observed for ash-bound chlorine, which cannot be explained with the increased chlorine concentration in the gas phase alone. Considering the trace element mercury, increased chlorine inputs did not necessarily lead to increased ionic mercury shares. Furthermore, no or only insignificant amounts of gaseous elemental mercury Hg⁰(g) could be determined downstream the fly ash filter system, while residual HgCl₂(g) concentrations do not differ significantly.     

Peculiarities in methanol action during liquefaction of different coal type

The peculiarities in methanol action during liquefaction of coals having different origin and rank were investigated. When liquefying sapropelic coals, the action of methanol does not differ from that of toluene. In the case of humic coals, methylation of aromatic fragments takes place and methylated liquid products are produced. The degree of alkylation increases with decrease in coal rank. The alkylation of model coal substances and some polyaromatic hydrocarbons was small. It was concluded that during coal liquefaction, reactive coal intermediates are subjected to alkylation.     

The redistribution of trace and minor elements during coal liquefaction

Radioactivation analysis of four sets of coal liquefaction feed and product materials provided information on the concentrations of forty trace and minor elements. Coal-derived oil was found to have low levels of most elements, comparable to crude petroleum. Aqueous process effluents were shown to have potentially troublesome levels, especially of Cr and Ba. The concentration data derived in this study and relevant process data were combined to construct elemental mass balances around the liquefaction process; these varied widely between about 80 and 140%, depending mostly on analytical errors. Enrichment of chromium and other transition metals in the conversion residues indicated a possible source through equipment erosion while consistent depletion of barium suggested a loss to aqueous stream particulate matter or possible reactor deposits.     

Nitrogen rate impacts on tropical maize nitrogen use efficiency and soil nitrogen depletion in eastern and southern Africa

Nutrient Cycling in Agroecosystems - Sub-Saharan Africa is facing food security challenges due, in part, to decades of soil nitrogen (N) depletion. Applying N fertilizer could increase crop yields...     

Evaluation of process conditions in the performance of yeast on alcoholic fermentation

This work studied the resistance of Saccharomyces cerevisiae Y904 to ethanol on an alcoholic fermentation process operated in fed-batch. The effect of temperature, inoculum size and substrate concentration on fermentation yield, productivity and residual sugars concentration was studied by a central composite design (CCD). Based on the CCD study, it was determined the optimum values of 240, 35?g/L, and 26°C for total reducing sugars, inoculum concentration and temperature, respectively. This set of conditions experimentally enabled a productivity of 6.0?g/L?h, a yield of 93% and an alcohol content of 113.6?g/L, after 10?h of fermentation. When yeast cells were adapted at 4°C, the inoculum pH adjusted to 2.5 and sugarcane broth used as substrate, a 94% yield and a 10.1?g/L.?h productivity were achieved.     

发酵对普洱茶中游离咖啡因含量的影响

目的探讨普洱茶发酵过程中咖啡因的存在形式及游离咖啡因含量的变化,为监测茶叶发酵程度,控制茶品质量提供依据。方法应用低pH沉淀结合高效液相色谱法(HPLC)检测普洱茶发酵全程中6个主要发酵阶段[一翻、二翻、三翻、四翻、五翻样品和出堆样品(熟茶)]样品的游离咖啡因和结合咖啡因含量。结果普洱茶发酵过程中,游离咖啡因含量逐渐降低,从一翻样品的(2.555±0.104)%降至出堆样品的(1.878±0.049)%,超过1/4的咖啡因与茶中的其他组分相结合,形成结合咖啡因。结合咖啡因的含量不断增加,四～五翻期间增幅最大,从0.084%增至0.647%;出堆样品中结合咖啡因的含量最高,为0.703%。结论发酵过程中,普洱茶中的游离咖啡因含量逐渐降低。本实验为监测茶叶发酵程度,控制茶品质量提供了依据。     

培养基氨基氮/总氮值对破伤风梭状芽胞杆菌产毒的影响

目的分析培养基氨基氮(amino nitrogen,AN)/总氮(total nitrogen,TN)值对破伤风梭状芽胞杆菌产毒的影响。方法选用不同制备方式的动物源性氮源,在TN相同且其他条件一致的情况下,分别按AN/TN目标值0.25、0.35、0.55配制培养基,用于破伤风梭状芽胞杆菌培养,分析不同AN/TN值与产毒的关系。结果不同AN/TN值与产毒结果之间差异有统计学意义(P0.001),呈高度负相关(r=-0.85,P0.001)。当AN/TN值在0.25~0.55范围内升高时,产毒呈下降趋势。AN/TN值为0.25时,产毒最高,平均值达105.5 Lf/m L。结论在一定范围内,降低培养基AN/TN值有利于产毒。