微波辐射法合成苄基-2-萘基醚的研究

在微波辐射条件下,以2-萘酚和氯化苄为原料,用氢氧化钠作碱剂,碘化钾作催化剂,以水和N,N-二甲基甲酰胺(DMF)为溶剂合成了苄基-2-萘基醚;采用单因素实验法,考察了反应物的摩尔比、催化剂用量、微波功率、辐射时间等因素对苄基-2-萘基醚产率的影响。实验结果表明:在n(2-萘酚):n(氢氧化钠):n(氯化苄):n(碘化钾)=1:1.1:1:0.018,水7 ml,DMF 25 ml,微波功率320 W和辐射时间75 s的优化条件下,苄基-2-萘基醚的产率可达88.03%。     

微波辐射一步法合成香料富马酸二苄酯的研究

目的:在微波辐射下,以顺丁烯二酸酐和苄醇为原料,在复合催化剂对甲苯磺酸-硫脲存在下以甲苯为带水剂一步合成了富马酸二苄酯.方法:通过熔点测定和红外光谱分析对产物进行了结构表征.采用正交试验法研究了反应物的摩尔比、催化剂用量、反应温度、辐射反应时间等对产物收率的影响.结果:实验结果表明,在微波功率为700W,n(顺丁烯二酸酸酐):n(苄醇)=1:5,复合催化剂用量为总投料量的7%,甲苯20mL,一酯化、转化、二酯化的温度分别为140℃、145℃、135℃,回流分水90min的条件下,富马酸二苄酯的收率可达92.50%.结论:采用微波辐射法复合催化合成富马酸二苄酯具有操作简便、反应时间短、产物收率高等特点.     

间溴苯乙醚的合成研究

以间溴苯酚、金属钠和溴乙烷为原料,乙醇为溶剂,碘化钾为催化剂合成了间溴苯乙醚。考察了反应物的摩尔比、反应温度及反应时间对产物收率的影响。实验结果表明:当n(间溴苯酚):n(金属钠):n(溴乙烷):n(碘化钾)=1:1:1.5:0.18,无水乙醇35mL,反应温度70℃,反应时间为5h时,间溴苯乙醚收率为82.6%。     

交联环糊精的制备及对苯酚吸附性能研究

采用甲苯二异氰酸酯(TDI)和β-环糊精(β-CD)进行交联反应,制备交联环糊精聚合物(β-CD-TDI)。通过正交试验找到了制备过程的最佳工艺参数为n(环糊精)∶n(异氰酸酯)=1∶9,复配催化剂的质量比为1∶1.5,反应温度70℃;用红外光谱(FT-IR)、扫描电镜(SEM)、热质量分析(TG)和X线衍射(XRD)等方法对交联环糊精聚合物进行了表征。通过拟合20℃条件下交联聚合物吸附苯酚的热力学曲线,发现其热力学符合Langmuir吸附等温式。     

酸性功能性离子液体催化合成二甘醇二苯甲酸酯

选用6种酸性功能化离子液体作为催化剂,催化苯甲酸和二甘醇酯化合成增塑剂二甘醇二苯甲酸酯(DEDB),通过实验考察反应温度、时间、催化剂种类及用量、原料投料比等工艺因素对合成收率的影响,确定了最佳反应条件:优选1-丁基磺酸-3-甲基咪唑对甲基苯磺酸盐([(CH_2)_4SO_3HMIm]TS)为催化剂,反应温度160℃,时间4.0 h,苯甲酸与二甘醇的摩尔比为2.2∶1,催化剂用量为二甘醇质量的10%,最终发现DEDB产率可达99.1%,且产品具有较高的品质。产物可以通过简单倾倒与离子液体催化剂分离,离子液体具有优异的重复使用性,使用10次后DEDB的产率仍有95.2%。     

葡萄糖-阿司匹林偶联物的合成

目的:为了改善阿司匹林药效,降低其毒副作用,探索出一条操作简便、成本低廉的糖基化方法,研制出一种副作用低的缓释药物葡萄糖-阿司匹林偶联物。方法:本文采用吡啶、浓NaOH溶液和浓硫酸作催化剂,在常压、不同温度、不同n(乙酰水杨酰氯):n(葡萄糖)条件下,合成葡萄糖-阿司匹林共价偶联物,通过FT-IR、~1HNMR对其结构进行了表征。研究催化剂、反应温度以及反应物料比对酯化反应的影响,同时利用紫外分光光度法测定偶联物的接枝率。结果:在常压,50℃,n(乙酰水杨酰氯):n(葡萄糖)=5:1,吡啶为催化剂条件下,偶联物的接枝率可达到54.9%。结论:在此反应中,吡啶是一种良好的催化剂;50℃是该反应的最佳反应温度;n(乙酰水杨酰氯):n(葡萄糖)=5:1时,偶联物的接枝率和乙酰水杨酰氯的转化率都比较高。     

微波法从黄连中提取黄连素的工艺研究

为了研究微波法从黄连中提取黄连素的效果,分别考察不同微波功率、原料浸泡时间、料液比(g/mL,下同)、提取次数、微波辐射时间对黄连素提取率的影响。结果微波法从黄连中提取黄连素的最佳工艺条件为:提取功率500W,原料浸泡时间24 h,料液比1∶120,提取次数2次,微波辐射时间3 min,提取率达5.61%,提取效果较好。与硫酸法、石灰法、乙醇浸取法相比,不仅提高了提取速度,并且更加环保。     

脂肪酸对中华哲水蚤摄食两种海洋微藻的指示作用

在室内以饥饿培养为对照,以海洋原甲藻(Prorocentrum micans)和中肋骨条藻(Skeletonema costatum)培养中华哲水蚤(Calanus sinicus),研究了各脂肪酸标记对中华哲水蚤摄食不同饵料的指示作用。结果显示,海洋原甲藻中18 ∶ 4ω3、22 ∶ 6ω3含量较高,中肋骨条藻中16 ∶ 1ω7、20 ∶ 5ω3的含量较高。二者分别表现出典型的甲藻门和硅藻门的脂肪酸组成特征。中华哲水蚤的脂肪酸组成有两个特点:(1)20 ∶ 5ω3和22 ∶ 6ω3的含量均较高;(2)其体内表征桡足类浮游植物食性、由桡足类自身合成的20 ∶ 1和22 ∶ 1脂肪酸占有相当的比例。虽然中华哲水蚤对不同脂肪酸的吸收和转化效率不同,但以脂肪酸作为标记还是成功的指示了中华哲水蚤对微藻的摄食。在饥饿培养中,首先消耗的是那些浮游动物自身不能合成的多不饱和脂肪酸,而结构脂肪酸都表现出了较高的保守性。结合各脂肪酸标记变化趋势和Pearson相关性分析的结果认为,18 ∶ 4ω3、18 ∶ 4ω3/16 ∶ 1ω7、∑18/∑16能较好的指示中华哲水蚤对海洋原甲藻的摄食,仅16 ∶ 1ω7/18 ∶ 4ω3能指示中华哲水蚤对中肋骨条藻的摄食。     

酿酒酵母脂酰-?9脱氢酶亚细胞定位表达及其对烟草脂肪酸合成的影响

以烟草Nicotiana tabacum L.为宿主植物,分别在细胞质内质网和质体内定位表达酿酒酵母Saccharomyees cerevisiae脂酰-CoA-Δ9脱氢酶(ScΔ9D),以期提高植物组织中棕榈油酸(16∶1Δ9)的积累量和分析该酶不同亚细胞定位表达对油脂代谢的影响。与野生型和空载体(对照)植物相比,转基因烟草植株叶片中单不饱和的棕榈油酸及顺式十八碳烯酸(18∶1Δ11)含量明显提高,而饱和的棕榈酸(16∶0)含量相应减少,多不饱和的亚油酸(18∶2Δ9,12)和亚麻酸(18∶3Δ9,12,15)含量亦降低。ScΔ9D质体定位表达烟叶中棕榈油酸及顺式十八碳烯酸含量分别是ScΔ9D细胞质内质网定位表达烟叶的2.7和1.9倍。这表明酵母脂酰-Δ9脱氢酶能在高等植物细胞中正确催化棕榈酸(16∶0)转化为棕榈油酸(16∶1Δ9),而且在质体内表达的效应显著高于在细胞质内质网上的效应。新建立了一种应用脂酰-CoA-Δ9脱氢酶代谢工程培育植物组织高水平合成积累棕榈油酸等ω-7脂肪酸的策略,有助于在生物量大的烟叶等营养器官中组装ω-7脂肪酸合成途径以生产优质生物燃油。     

响应面分析法优化乙酸乙酯萃取番茄红素条件的研究

采用响应面方法对番茄酱提取番茄红素过程中的乙醇预处理方法、萃取剂萃取时间等工艺条件进行了优化。采用Central Composite Design(CCD)设计法,对超声波提取法和微波提取法中的乙醇预处理、萃取剂萃取时间、超声波或微波萃取功率、溶剂量4个因素对番茄红素提取率的影响进行评价。结果显示,最佳提取方法为超声波提取法,无水乙醇∶番茄酱的2.05∶1(V/W);乙酸乙酯∶番茄酱10.1∶1(V/W);提取时间为490 s;超声波提取功率为405 W;提取率为94.42%。微波提取最佳方法为,无水乙醇∶番茄酱的2.11∶1(V/W);乙酸乙酯∶番茄酱10.1∶1(V/W);提取时间为372.6 s;微波提取功率为569.5 W;提取率为81.51%。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).