过氧乙酸灭菌效果及酸残留的实验研究

目的研究过氧乙酸灭菌的效果及酸的残留量对pH值的影响。方法用微生物学无菌检测法和pH值测定法。结果满载,少量装载,重复灭菌时达到无菌效果,△pH均在0.3～0.4之间。结论经过氧乙酸灭菌的塑料瓶能达到无菌要求,酸的残留量对pH值的影响不显著,生产上可用过氧乙酸灭菌法对不耐热的内包材进行灭菌。

Real-time PCR法检测注射用门冬酰胺酶制剂中大肠杆菌核苷酸残留

目的:建立可定量检测注射用门冬酰胺酶制剂中大肠杆菌核苷酸残留量的实时荧光定量PCR(Real-time PCR)方法,用于注射用门冬酰胺酶制剂中大肠杆菌核苷酸残留的质量控制。方法:选择大肠杆菌23S核糖体RNA基因为靶基因设计扩增引物,以ABI 7500 FAST平台为基础,建立基于SYBR Green荧光染料的Real-time PCR检测方法。结果:该法检测大肠杆菌核苷酸质量浓度在0.009 35~93 500 ng·m L^(-1)范围内线性良好,标准曲线的相关系数为0.999,定量限为0.009 35 ng·m L^(-1)。应用该法对2批注射用门冬酰胺酶制剂进行测定,均未检出大肠杆菌核苷酸残留。结论:该方法可用于注射用门冬酰胺酶制剂中大肠杆菌核苷酸残留的定量测定。

纤维膜聚结脱除双酚A反应液中残留的游离酸

研究了纤维膜聚结技术用于脱除双酚A反应液中残留游离酸的实验条件和纤维膜床层的再生条件。结果表明,在聚结温度70℃、95%乙醇用量2%、空速20～30 h-1、纤维膜床层体积1.0 cm3的条件下,可使双酚A反应液的酸度从0.014 mmol/L脱除至≤0.001mmol/L,满足双酚A反应液对酸度的要求;当双酚A反应液的处理量达到纤维膜床层体积的60倍时,床层必须采用丙酮进行再生;在丙酮用量6 mL和再生温度50℃的条件下,纤维膜床层可以得到完全再生。

无降解离子色谱法对食品中甲醛次硫酸氢钠残留的测定

首次报道了用水直接提取，离子色谱分离、测定食品中甲醛次硫酸氢钠的方法。采用IonPac ASl8作为分离柱，比较了NaHCO3-Na2CO3、Na2B4O7和KOH溶液的淋洗效果，发现KOH淋洗液效果最佳。实验研究了甲醛次硫酸氢钠的热稳定性及食品中常见阴离子与甲醛次硫酸氢钠的分离度。在选定的离子色谱测定条件下，甲醛次硫酸氢钠在0．1～200mg／kg的范围内有较好的线性。方法的加标回收率、相对标准偏差、检出限分别为88％～101％、3．3％～5．0％、0．05mg／kg。方法应用于年糕样品中残留甲醛次硫酸氢钠的检测，获得了满意的结果。

对高铁盐中的残留酸测定研究

在铁盐中所含三价铁离子量较高的条件下,对残留酸进行了分析实验研究。笔者提出了以10％的盐酸羟胺溶液还原高铁离子为亚铁离子,改变铁离子的水解特性,并以2.5g/L的甲基橙(MO)为指示剂,用氢氧化钠标准溶液进行滴定。实验证明:对硫酸铁、氯化铁等高铁盐试样进行了残留酸的酸碱滴定,测定的终点变色较为明显,结果较为准确,平行样品的精密度也较好,并适合于批量分析。

肝素中残留核苷酸检测方法国际协作研究

目的:美国药典会肝素原料个论中拟增加核苷酸杂质的检查方法,全球18家实验室参加了该方法的协作研究以确定检测方法和限度可行性。方法:征集国内2家企业共10批肝素钠样品,及USP提供的测试样品。使用Phenomenex Synergi FUSION-RP C18色谱柱(250 mm×4.6 mm,5μm),样品中的核酸杂质经酶解后,用0.02 mol·L-1醋酸铵和乙腈梯度洗脱分离,流速为1 mL·min-1,检测波长为260 nm。结果:系统适用性及测试样品结果均符合USP的要求,本实验室提交的数据全部被采纳,国内10批样品结果均符合USP拟定限度(<0.1%)。结论:该方法基本可行,较现有方法专属性高。

Indoor Toxicity of Emamectin Benzoate and Chlorantraniliprole Against Spodoptera litura and Their Residues on Lotus Plants

Spodoptera litura is the most threatening pest in lotus production,seriously affecting the lotus yield and quality.Emamectin benzoate and chlorantraniliprole,the main insecticides for controlling S.litura on vegetables,are widely used by farmers to control S.litura on lotus plants.To determine the application concentrations,control effects,and safety of the two insecticides in lotus fields,indoor experiments were conducted to determine the control effects of 200 g/L chlorantraniliprole(SC)and 5%emamectin benzoate(WDG),and the residues of the two insecticides in the water,lotus leaves,and lotus seeds after field application were determined by HPLC-MS/MS.The indoor experiment results showed that chlorantraniliprole and emamectin benzoate both had good control effects on S.litura,with the median lethal concentrations(LC50)of 17.700 and 1.694 mg/L,respectively.After unmanned aerial vehicle spraying of emamectin benzoate at 20 g/667m^(2),there was no residue of emamectin benzoate in the water or lotus leaves after 5 d.After spraying of chlorantraniliprole at 20 mL/667m^(2),the residual amounts in the water and lotus leaves after 9 d were 0.005 and 0.007 mg/L,respectively.No residue of the two insecticides was detected in lotus seeds(dry and fresh)2 h after spraying.Therefore,it was recommended that chlorantraniliprole and emamectin benzoate can be used to control S.litura in lotus fields during the growth period,while attention should be paid to the application interval for safety.Considering the safe harvesting of lotus seeds and leaves,it was recommended that the preharvest intervals of chlorantraniliprole and 5%emamectin benzoate should be 9 d.

Gas chromatographic method for the determination of hexaconazole residues in black tea

A highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. The proposed method is based on liquid-liquid extraction followed by gas chromatographic determination, using nitrogen phosphorus detector (GC-NPD) for the identification and quantitation of hexaconazole. The most appropriate solvent mixture for extracting hexaconazole residues from black tea was n-hexane:acetone at 1:1 (v/v). The extract was cleaned up by adsorption column chromatography using activated florisil. Performance of the method was assessed by evaluating quality parameters such as recovery value, repeatability, reproducibility, linearity and limits of detection and quantitation. When the method was assessed for repeatability, the percentage of recovery ranged between 86% and 96% while the relative standard deviation was between 0.30% and 2.35%. In studies on reproducibility the recovery ranged from 81% to 85% and relative standard deviation from 1.68% to 5.13%, implying that the method was reliable. A field trial was conducted to verify the application of this method with real samples. Results prove that the validated method was suitable for extracting hexaconazole residues.

Application of Molecular Distillation Process to Extend the True Boiling Point Curve of Petroleum Residues 400 ℃ ＋

True Boiling Point （TBP） distillation is one of the most common experimental techniques for determination of petroleum properties. The methods for performing TBP distillation experiments are described by ASTM D2892 and by ASTM D5236. However, these methods are established for petroleum fractions that reach temperatures up to 565 ~C. In this work, two petroleum residues were distilled in a falling film molecular distillation prototype and the data were used to obtain the extension of the TBP curve above a temperature of 565 ~C. It was possible to extend the TBP curve of both petroleum up to temperatures close to 700 ~C with consistency and continuity in comparison to the standard curve. In addition, an amount of raw material that was been treated as residue could be reused.

Degradation of ethyl xanthate in flotation residues by hydrogen peroxide

The degradation behavior of ethyl xanthate(EX) salt was the most widely used collector in sulfide mineral flotation and emission of flotation tailings with residual EX was harmful to environment. In this work, hydrogen peroxide(H2O2) was investigated by UV-visible spectroscopy(UV/Vis) at different p H values from 3 to 12. For p H value from 5 to 12, EX was oxidized into ethyl per xanthate(EPX) by H2O2. Then EPX was further oxidized into thiosulfate(TS) salt rather than ethyl thiocarbonate(ETC) and this step was the reaction-limited step. Then depending on p H values, TS was degraded into sulphate and carbonate salts(p H>7) or elemental sulfur(p H<7). The kinetics data show that the degradation rate of EX increases with increasing the H2O2 concentration and is independent on the p H values. Without H2O2, EX is hydrolyzed to carbon disulfide fast at p H value <3.0, but the reaction of hydrolysis is undetectable at p H value >3.0 during test time.

Solid superacid-catalyzed hydroconversion of an extraction residue from Lingwu bituminous coal

A solid superacid was prepared as a catalyst. The catalyst was characterized by ammonia temperature- programmed desorption, surface property measurement, and analyses with scanning electron micros- copy and Fourier transform infrared spectrometry. A extraction residue from Lingwu subbituminous coal was subject to non-catalytic and catalytic hydroconversion using cyclohexane as the solvent under pres- surized hydrogen at 300 ℃ for 3 h. The results show that the total yield of petroleum ether-extractable arenes from catalytic hydroconversion is much higher than that from non-catalytic hydroconversion. The cleavage of Car-Cask bonds in the residue could significantly proceed during catalytic hvdrncnnvarsion

A Test for Stabilization of an Oligomeric Protein by Introduction of Aromatic Residues into the Interface

The design of variants to enhance conformational stability of proteins is an important aspect of protein engineering. Oligomeric proteins are often stabilized by aromatic clusters located within the subunit interfaces. In the present study, the authors constructed five variants of Ps3aHSD （Pseudomonas sp. B-0831 3a-hydroxysteroid dehydrogenase） in which one or two residues at the dimer interface were replaced with aromatic residues, and examined the effects of introducing aromatic residues in this region on protein thermostability. Under their experimental conditions, all variants formed dimers, similar to wild-type Ps3aHSD. Thermal denaturation experiments indicated that Tm of all variants was 0.2-16.2 °C lower than that of wild-type protein, indicating less stable thanwild-type protein. The results collectively suggest that aromatic residues of natural oligomeric proteins are strictly posted in the interface to facilitate optimal interactions and avoid conformational strain.

Residue curve maps of ethyl acetate synthesis reaction

The residue curve maps are considered as a powerful tool for the preliminary design of reactive distillation. The residue curve maps of ethyl acetate synthesis reaction were calculated based on the pseudo-homogeneous rate-based kinetic model and the NRTL activity coefficient model. The results show that the unstable node branch emerges from the ethyl acetate/water edge, moving toward the chemical equilibrium surface with the increase of Damkoeler value （D）, and the node reaches the ternary reactive azeotrope when D-∞ eventually. Conceptual design for the ethyl acetate synthesis of reactive distillation based on the residue curve maps is presented at last.

Development on the Technique of Total Recovery of Benzoic Acid Residue

Benzoic acid residue is solid waste produced from the production of benzoic acid by oxidizing toluene.Because it contained important chemical raw materials such as benzoic acid,benzyl benzoate and fluorenone,it is necessary to recover them from the residue.In this work the technique featured with high efficiency evaporation and vacuum distillation was developed to obtain total recovery and utilization of the benzoic acid residue.By controlling the operation temperature at 260℃ and the pressure of 16kPa in the rising and falling film evaporators,heavy components separated efficiently from the residue can be polymerized and the light components consisting of 63% of the residue entered into a benzoic acid vacuum distillation column.Keeping the temperature of polymerization at(280±10)℃,coumarone resin was produced after adjusting the softening point according to the market requirements.Vacuum distillation was operated under the following conditions:top temperature at 186℃,top pressure of 16kPa,bottom temperature at 240-250℃,reflux ratio being 3︰1.Benzoic acid of 98% purity was distilled out from the column as a side stream and the bottom product was crude benzyl benzoate.By the developed technique,the benzoic acid residue was splitted into three products,benzoic acid,crude benzyl benzoate and coumarone resin without any surplus waste.

Separation of Benzoic Acid Residue by Flash-Vacuum Distillation-Melt Crystallization

A large amount of residue including benzoic acid, benzyl benzoate and fluorenone can form in the production of benzoic acid by oxidizing toluene. To recycle the resources and reduce secondary pollution, the treatment of benzoic acid residue was carried out to obtain the three purified materials by flash-vacuum distillation combination method, and the influence of the operating parameters, such as the top pressure, reflux ratio and top and bottom temperatures was investigated to obtain the best operating conditions. The experimental results show that the benzoic acid purity can reach 97% through distillation under the following conditions： the top pressure is 1 600 Pa, the bottom temperature is 190--200℃, the top temperature is 130--135℃, and reflux ratio is 5：1. The best operating conditions for benzyl benzoate distillation column are： the top pressure is 400 Pa, bottom temperature is 250-- 260 ℃, the top temperature is 150--160 , and reflux ratio is 5：1. The benzyl benzoate purity can reach 95%, and the fiuorenone purity can reach 92 %. When refined by melt crystallization, the benzoic acid purity can be improved up to 99.6%, and the purities of benzyl benzoate and fluorenone are both above 95%.

Analysis of Residues Formed during the Liquefaction Process of Wheat Straw

Wheat straw(WS) was liquefied to analyze the reaction process of WS under the acid-catalyzed conditions. WS was liquefied almost completely in the presence of ethylene carbonate/ethylene glycol(EC/EG) blend solvents within 40min at 150 ℃. The residues with different liquefaction time were investigated by SEM, FTIR, and XRD. The residues exhibited loose structure and rough surface due to the presence of stacked irregular platelets. The FTIR results demonstrated that lignin was more easily liquefied in the presence of EC/EG blend solvents than cellulose because the bands of cellulose were stronger and the bands of lignin were much weaker during the liquefaction process of WS. Moreover, the XRD result of all residues declared that WS was gradually liquefied, dissolved and decomposed to small fragments of lower molecular weight, and condensed in part in the later stage of liquefaction.

Amendment of Acid Soils with Crop Residues and Biochars

The liming potential of some crop residues and their biochars on an acid Ultisol was investigated using incubation experiments. Rice hulls showed greater liming potential than rice hull biochar, while soybean and pea straws had less liming potential than their biochars. Due to their higher alkalinity, biochars from legume materials increased soil pH much compared to biochars from non-legume materials. The alkalinity of biochars was a key factor affecting their liming potential, and the greater alkalinity of biochars led to greater reductions in soil acidity. The incorporation of biochars decreased soil exchangeable acidity and increased soil exchangeable base cations and base saturation, thus improving soil fertility.

Mechanistic insights for efficient inactivation of antibiotic resistance genes: a synergistic interfacial adsorption and photocatalytic-oxidation process

Advanced oxidation processes(AOPs) have been applied to address multiple environmental concerns including antibiotic resistance genes(ARGs). ARGs have shown an increasing threat to human health,and they are either harbored by antibiotic-resistant bacteria(ARB) or free in the environment.However, the control of ARGs has been substantially limited by their low concentration and the limited knowledge about their interfacial behavior. Herein, a novel AOP catalyst, Ag/TiO_(2)/graphene oxide(GO),combined with a polyvinylidene fluoride(PVDF) ultrafiltration membrane was designed with a synergistic interfacial adsorption and oxidation function to inactivate ARGs with high efficiency in both model solutions and in secondary wastewater effluent, especially when the residue concentration was low.Further analysis showed that the mineralization of bases and phosphodiesters mainly caused the inactivation of ARGs. Moreover, the interfacial adsorption and oxidation processes of ARGs were studied at the molecular level. The results showed that GO was rich in sp^(2) backbones and functional oxygen groups,which efficiently captured and enriched the ARGs via p-p interactions and hydrogen bonds. Therefore,the photogenerated active oxygen species attack the ARGs by partially overcoming the kinetic problems in this process. The Ag/Ti O2/GO catalyst was further combined with a PVDF membrane to test its potential in wastewater treatment applications. This work offers an efficient method and a corresponding material for the inactivation and mineralization of intra/extracellular ARGs. Moreover, the molecularlevel understanding of ARG behaviors on a solid–liquid interface will inspire further control strategies of ARGs in the future.