响应面优化十六烷基二甲基苄基氯化铵改性 蒙脱土脱除玉米油中玉米赤霉烯酮工艺

为提高十六烷基二甲基苄基氯化铵改性蒙脱土（1627-MMT）脱除玉米油中玉米赤霉烯酮（ZEN）的效率,在对比不同改性蒙脱土对玉米油中ZEN脱除效果的基础上,以ZEN吸附脱除率为考察指标,采用单因素实验和响应面实验优化1627-MMT脱除玉米油中ZEN的工艺条件（1627-MMT添加量、吸附时间、吸附温度）,并测定脱毒前后玉米油的理化性质及总甾醇和总生育酚含量变化。结果表明：相比其他3种改性蒙脱土,1627-MMT的ZEN脱除效果最佳;1627-MMT脱除玉米油中ZEN的最优工艺条件为1627-MMT添加量5%、吸附温度105 ℃、吸附时间23 min,在此条件下ZEN吸附脱除率为（89.16±0.10）%,脱毒后玉米油中ZEN含量为349.64 μg/kg,符合欧盟标准限量要求（≤400 μg/kg）;脱毒后玉米油的红值下降了72.34%,酸值下降了41.67%,过氧化值下降了42.00%,总甾醇和总生育酚的保留率分别为92.07%和85.34%,脂肪酸组成及含量无明显变化。综上,1627-MMT不仅可有效脱除玉米油中ZEN,还可降低玉米油的酸值、过氧化值及色泽,并对玉米油中的甾醇、生育酚含量及脂肪酸组成影响较小,在玉米油中ZEN 的脱除中具有一定的应用潜力。     

Hydrodynamic and chemical factors in clogging by montmorillonite in porous media

Clogging by colloid deposits is important in water treatment filters, groundwater aquifers, and petroleum reservoirs. The complexity of colloid deposition and deposit morphology preclude models based on first principles, so this study extends an empirical approach to quantify clogging using a simple, one-parameter model. Experiments were conducted with destabilized suspensions of sodium- and calcium-montmorillonite to quantify the hydrodynamic and chemical factors important in clogging. Greater clogging is observed at slower fluid velocity, consistent with previous investigations. However, calcium-montmorillonite causes 1 order of magnitude less clogging per mass of deposited particles compared to sodium-montmorillonite or a previously published summary of clogging in model granular media. Steady-state conditions, in which the permeability and the quantity of deposited material are both constant, were not observed, even though the experimental conditions were optimized for that purpose. These results indicate that hydrodynamic aspects of clogging by these natural materials are consistent with those of simplified model systems, and they demonstrate significant chemical effects on clogging for fully destabilized montmorillonite clay.     

Bioactive amines in fresh, canned and dried sweet corn, embryo and endosperm and germinated corn

The types and levels of free bioactive amines in different corn products were determined. The amines were analyzed by ion pair-HPLC, post-column derivatization with o-phthalaldehyde and fluorimetric detection. Fresh sweet corn contained mainly spermidine followed by putrescine. Spermine, cadaverine, phenylethylamine, histamine and agmatine were also present at low levels. The profile and levels of amines changed significantly in canned and dried corn. Putrescine was the prevalent amine in canned corn whereas spermine was prevalent in dried corn. Germinated corn had significantly higher spermidine, spermine and putrescine levels. The embryo of the corn contained significantly higher spermine levels compared to the endosperm. These results indicate that corn is a good source of polyamines and that the different types of corn products available can be used to provide a profile of amines according to specific dietary need.     

Zearalenone contamination in corn for human consumption in the state of Tlaxcala,Mexico

Corn from various regions of the state of Tlaxcala, Mexico was sampled to determine whether or not corn which is consumed by humans is contaminated with the estrogenic mycotoxin zearalenone (ZEA). In order to quantify this mycotoxin, a method with adequate sensitivity using solid–liquid extraction and high-performance liquid chromatography (HPLC) with UV diode array detection was optimized. ZEA and zearalanol, used as an internal standard, were extracted from 5 g of a finely ground corn sample with an 85:15 v/v methanol:water solution, cleaned by way of a Florisil column, defatted with n-hexane, and subsequently re-extracted with chloroform. The separation was performed on a reverse phase analytical column. Detection was confirmed by on-line simultaneous UV spectral scanning during the chromatographic run. The method’s limit of detection was 0.7 ng/g and the recovery average was 90%. Analysis of 24 samples indicates that approximately 70% of the monitored samples were contaminated with zearalenone, with levels ranging from 3 to 83 μg/kg of corn kernels.     

Evaluation of mesoporous cyclodextrin-silica nanocomposites for the removal of pesticides from aqueous media

The treatment of aqueous solutions containing various pesticides by cyclodextrin-functionalized mesoporous silica adsorbents was investigated. The pesticides studied belonged to three chemical structure classes: hexachlorocyclohexane-based, hexachlorobicycloheptene-based, and p,p' substituted biphenyl-based pesticides. The solutions studied contained a mass concentration with respect to each pesticide in the range of 0.060-0.270 microg/mL, values that are consistentwith the low levels typically encountered in environmental samples. Adsorbents containing low to intermediate amounts of cyclodextrin groups were found to have optimal adsorption affinity toward the pesticides. The materials were particularly specific toward p,p'substituted diphenyl-based pesticides such as DDT and DDE.     

水酶法提取湿磨法玉米胚芽油的研究

以玉米胚芽为原料,对同时提取蛋白和水酶法提油的工艺条件进行了研究.研究结果表明,玉米胚芽首先在碱性条件下提取分离其中的蛋白质,剩下的料液(渣和乳化层)再用水酶法提取其中的油脂.纤维素酶可显著提高玉米胚芽油的收率,其最适参数为:料液比为1:3,蒸汽预处理时间为20min,酶添加量为1%,反应pH为5.5,温度为55℃,酶解时间为6 h.     

Rate and extent of aqueous perchlorate removal by iron surfaces

The rate and extent of perchlorate reduction on several types of iron metal was studied in batch and column reactors. Mass balances performed on the batch experiments indicate that perchlorate is initially sorbed to the iron surface, followed by a reduction to chloride. Perchlorate removal was proportional to the iron dosage in the batch reactors, with up to 66% removal in 336 h in the highest dosage system (1.25 g mL(-1)). Surface-normalized reaction rates among three commercial sources of iron filings were similar for acid-washed samples. The most significant perchlorate removal occurred in solutions with slightly acidic or near-neutral initial pH values. Surface mediation of the reaction is supported by the absence of reduction in batch experiments with soluble Fe2+ and also by the similarity in specific reaction rate constants (kSA) determined for three different iron types. Elevated soluble chloride concentrations significantly inhibited perchlorate reduction, and lower removal rates were observed for iron samples with higher amounts of background chloride contamination. Perchlorate reduction was not observed on electrolytic sources of iron or on a mixed-phase oxide (Fe3O4), suggesting that the reactive iron phase is neither pure zerovalent iron nor the mixed oxide alone. A mixed valence iron hydr(oxide) coating or a sorbed Fe2+ surface complex represent the most likely sites for the reaction. The observed reaction rates are too slow for immediate use in remediation system design, but the findings may provide a basis for future development of cost-effective abiotic perchlorate removal techniques.     

水酶法提取玉米胚芽油的优化工艺研究

对水酶法提取玉米胚芽油的最适酶进行了确定,以纤维素酶和中温α-淀粉酶复合使用效果最好.在纤维素酶和中温α-淀粉酶复配比例为1:1条件下,用响应面分析法对水酶法提取玉米胚芽油的工艺进行了优化,以玉米胚芽油的得率为响应值,确定了酶水解的最适参数:液固比5.1:1,蒸汽处理19.6 min,酶的添加量1.037%(V/W),酶解时间6 h.在此条件下的提油率为89.75%.     

高效液相色谱法对玉米中玉米赤霉烯酮的测定

研究了高效液相色谱法测定玉米中玉米赤霉烯酮的方法.样品借鉴了GB/T 19540-2004中提取玉米赤霉烯酮的方法,通过Oasis HLB净化柱对提取液净化,以agilent extent C18色谱柱为分离柱,乙腈-水(V水:V乙腈=55:45)为流动相进行荧光检测(λex=235 nm,λem=460 nm).玉米赤霉烯酮的质量浓度在12～2 400μ/kg范围内呈良好线性,相关系数为0.9994,对添加高、中、低3个浓度玉米赤霉烯酮的玉米样品进行加标回收试验,平均回收率分别为96.736%、93.839%、86.240%,变异系数在1%～10%之间,最低检测限为10μ/kg.此方法对玉米中玉米赤霉烯酮的检测是可行的,且可给谷物中玉米赤霉烯酮检测方法优化提供参考.     

复合磷脂酶水相体系酶法制备甘油磷脂酰胆碱的研究

采用复合磷脂酶在水相体系中酶解大豆卵磷脂制备甘油磷脂酰胆碱(GPC),磷脂酶A1和磷脂酶A2复合酶解作用,不仅有效地缩短了酶解时间,更能提高GPC的得率。通过响应面优化试验确定最佳酶解条件为:底物质量浓度61 g/L,酶解温度45.2℃,磷脂酶A1添加量16.86 U/m L,磷脂酶A2添加量21.98 U/m L,Ca Cl2添加量5.18 g/L。在最佳酶解条件下酶解2 h,GPC得率平均值为96.25%。     

Mycotoxins in cereal grain. Part IX. Zearalenone and Fusaria in wheat,barley, rye and corn kernels

Toxigenic Fusaria, producing zearalenon, appeared in 31% of cereal grain samples. However zearalenone was present only in 0.5% of 584 cereal samples assayed during 1979-1981 at level 0.2-1.2 mg/kg. Fungi able to form zearalenone were present mainly in grain collected from breeding stations. Fusarium culmorum was dominant among toxigenic isolates from domestic cereals and yield of zearalenone was up to 700 mg/kg.     

水相体系酶法制备溶血磷脂酰乙醇胺研究

探索了磷脂酶A1在水相体系中酶解制备溶血磷脂酰乙醇胺(LPE)的可行性,并进行了酶解条件对LPE相对含量的影响研究。得到最佳酶解条件为:磷脂酰乙醇胺(PE)的纯度为80%,液料比10∶1,酶解温度35℃,酶添加量0.04 m L/g,Ca Cl2添加量0.010 g/m L,酶解时间30 min。在最佳酶解条件下,得到酶解产物中的LPE相对含量为42.0%。     

Mitigation of ammonia and hydrogen sulfide emissions by stable aqueous foam-microbial media

Stable aqueous foam-microbial media consisting of protein-based foams and odor-degrading bacteria were developed to control the emissions of odorous compounds. The optimum foam formulation was determined based on foam characteristics including 50% drainage time, foam lifetime, and foam expansion ratio. When only the aqueous foam was applied onto the surface of a test odor source (i.e., swine manure), ammonia emission was completely suppressed for about 177, 225, 265, 297, and 471 min when the height of foam barrier was 2.5, 5, 10, 15, and 30 cm, respectively. According to the increasing foam height, ammonia emission rates after breakthrough points decreased to 0.16, 0.13, 0.09, 0.07, and 0.02 mg/m3/min, and thus volatilized ammonia concentrations decreased significantly after 600 min. Hydrogen sulfide was similarly suppressed. Ammonia emission was better controlled by incorporating odor-degrading bacteria into the aqueous foam. The odor suppression capacity of the 5-cm foam barrier with microbes was more than eight times greater than that of the barrier only and was similar to that of 30-cm foam barrier without microbes after 1440 min. A significant amount of dinitrogen gas was evolved by the foam-microbial media, indicating a successful biological transformation of ammonia.     

A study of gelatine-methylcellulose compatibility in aqueous media

The phase-volume-ratio method has been used to study the phase diagrams (at 35 £C) of the system gelatine-methyl-cellulose-water at pH's 4.75 and 3.0 and also in the presence of 0.5 M NaCl. Generally, the data obtained provide support for the low compatibility of proteins and neutral polysaccharides in the isoionic protein point and demonstrate the possibility of the improvement of the gelatine-methylcellulose compatibility by shifting pH from the isoionic gelatine point. In addition, it has been shown that NaCl produces a small effect on the gelatine-methylcellulose compatibility. The phase diagrams of the system gelatine-methylcellulose-water are asymmetric, which opens the possibility of gelatine solutions being concentrated by the membrane-free osmosis.     

高效液相法同时检测谷物中玉米赤霉烯酮和赭曲霉毒素A

该研究开发一种快速、灵敏同时检测玉米、小麦和稻米中玉米赤霉烯酮(zearalenone,ZEN)和赭曲霉毒素A(ochratoxin A,OTA)的高效液相色谱检测方法。将样品采用乙腈/水(80/20,体积比),200 r/min,30℃振荡提取30 min后,经Oasis PRiME HLB固相萃取柱净化后,上样检测。该方法ZEN和OTA检测限(limit of detection,LOD)为3.7μg/kg和0.11μg/kg,定量限(quantification Limit,LOQ)为12.25μg/kg和0.38μg/kg,线性范围分别为10μg/kg^2000μg/kg和0.2μg/kg^200μg/kg,加标样品中不同浓度的ZEN和OTA回收率为83.0%~101.3%,日内精密度和日间精密度分别为3.12%~7.03%和3.57%~9.3%。该方法适用于玉米、小麦和稻米中ZEN和OTA的同时检测。     

高效液相色谱法同时测定谷物中的赭曲霉毒素和玉米赤霉烯酮

采用反相高效液相色谱法同时测定谷物中的赭曲霉毒素和玉米赤霉烯酮.以ODS C18(250mmx4.6mm,5μm)为色谱柱,乙腈-2%乙酸(两者体积比40:60)为流动相,荧光检测器检测, Ex 325nm, Em 455 nm.赭曲霉毒素A和玉米赤霉烯酮的线性范围分别为1～100μg/L和10～100)μg/L,检出限分别为0.025 ng和0.26 ng.5种样品的检测中两种生物毒素的加标回收率在75%～110%之间.该方法灵敏、准确,适用于谷物中赭曲霉毒素和玉米赤霉烯酮的栓测.     

Complexation of microcystins and nodularin by cyclodextrins in aqueous solution, a potential removal strategy

Cyanotoxins are potent toxic compounds produced by cyanobacteria during algal blooms, which threaten drinking water supplies. These compounds can poison and kill animals and humans. The host-guest interactions of α-, β-, and γ-cyclodextrins (CD) with problematic cyanotoxins, including microcystins (MCs) and nodularin (NOD), were investigated to demonstrate the potential application of CDs for the removal of these toxins from drinking water or applications related to their separation or purification. MCs and NOD have a hydrophobic Adda chain, which contains diene and benzene functional groups. The complexation of these cyanotoxins with CDs was monitored by nuclear magnetic resonance (NMR). The (1)H NMR spectra for MCs are unchanged upon addition of α-CD (smallest host). However, addition of larger hosts, β-CD and γ-CD, leads to significant changes in chemical shifts of the benzene and diene resonances on the 3-amino-9-methoxy-2,6,8-trimethal-10-phenyldeca-4,6-dienoic acid (Adda) chain of MCs and NOD. Solution pH, natural organic matter, and salinity do not appreciably influence the host-guest complexation under our experimental conditions. The experimental binding constants for MCs and NOD with γ-CD are relatively strong, ranging from 1155 to 507 M(-1). The observed changes in chemical shifts for specific protons and competitive binding experiments demonstrate a 1:1 inclusion complex between γ-CD and MCs or NOD, with the Adda chains threading through the CD ring, resulting in an inclusion complex. Our results suggest that CD-type substrates are useful hosts for the complexation of MCs and NOD. CDs can be readily attached to a number of polymeric or solid supports and their functionality tailored to strengthen specific host-guest interactions. With further development of such materials, CD host-guest chemistry may find direct application in the removal and/or separation science of these compounds.     

Ionizing radiation-induced destruction of benzene and dienes in aqueous media

Pulse radiolysis with spectrophotometric and conductometric detection was utilized to study the formation and reactions of radicals from benzene and dienes in aqueous solutions. The benzene OH adduct, *C6H6OH, reacts with O2 (k = 3 x 10(8) L mol(-1) s(-1)) in a reversible reaction. The peroxyl radical, HOC6H6O2*, undergoes O2*- elimination, bimolecular decay, and reaction with benzene to initiate a chain reaction, depending on the dose rate, benzene concentration, and pH. The occurrence of the chain reaction is demonstrated in low-dose-rate gamma radiolysis experiments where the consumption of O2 was monitored. 1,4-Cyclohexadiene, 1,4-hexadiene, and 1,4-pentadiene form OH-adducts and undergo H-abstraction by O*- radicals. The OH-adducts react with O2 to form peroxyl radicals. These peroxyl radicals, however, do not undergo unimolecular O2*- elimination but rather decay by second-order processes, which lead to subsequent steps of O2*- elimination.     

利用玉米淀粉黄浆水发酵生产细菌纤维素的培养基优化

玉米淀粉黄浆水是生产淀粉过程中排放的高浓度有机废水,以其作为Acetobacter xylinum DS398的基础培养基发酵细菌纤维素。采用Plackett-Burman设计和Box-Behnken响应面分析法对培养基成分进行优化,并对产物进行表征。以纤维素干重为响应值,从7个相关影响因素筛选出3个显著因子:蔗糖、磷酸二氢钾和乙醇。在此基础上,根据Box-Behnken响应面分析法确定以上三因素的最佳浓度。最优的玉米淀粉黄浆水培养基组分为:玉米黄浆水稀释比1∶4,蔗糖3.32 g/100 m L,CaCl₂0.3 g/100 m L,KH₂PO₄0.12 g/100 m L,Mg SO₄0.05 g/100 m L,柠檬酸0.2 g/100 m L,乙醇1.50 m L/100 m L,细菌纤维素产量达到1.11 g/100 m L,为优化前的1.63倍。结果表明经优化后黄浆水培养基能够满足Acetobacter xylinum生长代谢的需要,细菌纤维素产量得到显著提高;同时傅立叶红外光谱图和场发射扫描电镜图显示产物是纯度较高的纤维素,微观结构与椰果相似。