Zn-Ca-Fe氧化物催化水解微晶纤维素

以尿素为沉淀剂制备了一系列复合金属沉淀物,将其在高温条件下煅烧获得一系列复合金属氧化物固体催化剂,并将其用于催化微晶纤维素的水解反应;考察了反应温度、反应时间、搅拌转速、催化剂用量和微晶纤维素用量对反应的影响。实验结果表明,在反应温度160℃、反应时间20 h、搅拌转速400 r/mnin、微晶纤维素2.0 g、Zn-Ca-Fe氧化物0.9 g和H_2O 200 mL的条件下,微晶纤维素的转化率高达42.56%,葡萄糖的收率为69.20%,且微晶纤维素水解液为中性溶液。在相同反应条件下,Zn-Ca-Fe氧化物可重复使用5次,其催化活性无明显降低。     

Influence of water activity,temperature and incubation time on the simultaneous production of deoxynivalenol and zearalenone in corn (Zea mays) by Fusarium graminearum

The production of deoxynivalenol and zearalenone by Fusarium graminearum was studied under different culture conditions (water activity, temperature and incubation time). The maximum levels of both toxins were obtained at the 35th day of incubation, the zearalenone level being much higher than the deoxynivalenol. The culture conditions that gave higher yields of deoxynivalenol were at 22 and at 28 °C (6.0 and 5.5 mg/kg ), after 35 days. At an incubation temperature of 28 °C 16 days, followed by 12 °C, for the same time, the production was low (1.1 mg/kg). The highest level of zearalenone was obtained at 28 °C for 16 days, followed by incubation at 12 °C (36.7mg/kg) at the 35th day. When the temperature was constant at 28 °C, the zearalenone production was lower (3.0 mg/kg) than when incubated at 22 °C (12.3 mg/kg), at the 35th day. Fusarium graminearum did not produce deoxynivalenol and zearalenone at 37 °C.     

Research advances in traditional and modern use of Nelumbo nucifera: phytochemicals,health promoting activities and beyond

Abstract

Nelumbo nucifera, or sacred lotus, has been valuable for us to use as vegetable, functional food, and herb medicine for over 2,000?years. The purpose of this article is to systematically review the traditional/modern uses, chemical compositions and pharmacological activities on different parts of N. nucifera. Traditionally, this plant has been used to treat chronic dyspepsia, hematuria, insomnia, nervous disorders, cardiovascular diseases, and hyperlipidemia. Now, phytochemical investigations on different parts of N. nucifera have indicated a wide spectrum of at least 255 constituents belonging to different chemical groups, including proteins, amino acids, polysaccharides, starch, flavonoids, alkaloids, essential oils, triterpenoids, steroids, and glycosides. Meanwhile, its pharmacological activities, including anti-obesity, antioxidant, anti-inflammatory, cardiovascular, hepatoprotective, hypoglycemic, hypolipidemic, antitumor, memory-improving and antiviral activities, have also been reviewed, together with its applications in health food industry and clinic uses of its single plant or herbal formulae. Herein, this review will provide state-of-the-art overview on its traditional and modern uses in food industry and medicines, together with the comprehensive profiles of phytochemicals, and health promoting bioactivities of this valuable plant. In addition, the new perspectives and future challenges in the research on lotus are also outlined.     

20种观赏丛生竹的抗寒性测定

选取湖南省森林植物园观赏竹园中经多年观测,在自然条件下生长良好的19种观赏丛生竹及抗寒性较差的撑篙竹作对比,以其离体叶片为试材,用电导法测定其抗寒性．结果表明：20种观赏丛生竹种的抗寒性存在显著差异;其抗寒性强弱为慈竹〉长沙青皮竹〉孝顺竹〉小琴丝竹〉金丝慈竹〉观音竹〉银丝竹〉凤尾竹〉麻竹〉花眉竹〉粉单竹〉青丝黄竹〉鼓节竹〉坭竹〉花慈竹〉花竹〉大眼竹〉绵竹〉信宜石竹〉撑篙竹,这与大田自然生长观测研究结果一致．-9℃低温胁迫时,19种丛生观赏竹测试都没有出现半致死量,说明所选丛生竹在-9℃时可以生长,或经低温冻害后,翌春能恢复生长．长沙冬季低温常年仅为（-2—4）℃,极端最低温-9．5℃,因此,所筛选的19种观赏丛生竹均可以在长沙及湖南其余的大部分地区栽培．本研究为观赏丛生竹的选择应用提供科学依据．     

Electrochemical synthesis and photocatalytic property of cuprous oxide nanoparticles

Cuprous oxide (Cu₂O) nanoparticles of 35 nm in crystal size have been successfully synthesized via electrochemical method in alkali NaCl solutions with copper as electrodes and K₂Cr₂O₇ as additive. Photocatalytic degradation of methyl orange (MeO) in aqueous Cu₂O solution was investigated under either ultraviolet (UV) light or sunlight. X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformation infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–vis) and X-ray photoelectron spectroscopy (XPS) were introduced to characterize the samples. The results indicate that electric current shows no obvious effect on the growth of Cu₂O nanocrystals and that 97% of MeO can be decolorized under UV irradiation for 2 h or under sunlight for 3 h when amount of Cu₂O is 2 g/L. Recycling use of the catalyst revealed that Cu₂O still has a high photocatalytic efficiency when repeatedly used for four times. Cu₂O nanoparticles still kept its cubic crystal phase, but fractionally oxidized to be CuO after the photocatalysis. Compared with the original Cu₂O nanoparticles, there has 1 eV shift of Cu 2p electron and 1.6 eV shift of Cu Auger signals for the Cu₂O powders after four times photocatalysis. Some new peaks can also be observed at 401.1, 237.4 and 170.2 eV in the Cu₂O powders after photocatalysis.     

Characteristics of a Pd–oxide–In0.49Ga0.51P high electron mobility transistor (HEMT)-based hydrogen sensor

An interesting hydrogen sensor based on a high electron mobility transistor (HEMT) device with a Pd–oxide–In_0.49Ga_0.51P gate structure is fabricated and demonstrated. The hydrogen sensing characteristics including hydrogen detection sensitivity and transient responses of the studied device under different hydrogen concentrations and temperature are measured and studied. The hydrogen detection sensitivity is related to a change in the contact potential at the Pd/insulator interface. The kinetic and thermodynamic properties of hydrogen adsorption are also studied. Experimentally, good hydrogen detection sensitivities, large magnitude of current variations (3.96 mA in 9970 ppm H₂/air gas at room temperature) and shorter absorption response time (22 s in 9970 ppm H₂/air gas at room temperature) are obtained for a 1.4 μm × 100 μm gate dimension device. Therefore, the studied device provides a promise for high-performance solid-state hydrogen sensor, integrated circuit (IC) and micro electro-mechanical system (MEMS) applications.     

13种植物多酚提取物抗氧化活性分析及其对冻藏未漂洗鱼糜品质的影响研究

目的 分析13种植物多酚提取物抗氧化活性并研究其对冻藏未漂洗鱼糜品质的影响。方法 比较分析了石榴、芝麻、蓝莓、姜黄、迷迭香、薄荷、葡萄、橄榄、草莓、马鞭草、茶籽、燕麦、莲子皮13种植物多酚提取物的抗氧化活性及对冻藏未漂洗鱼糜脂质氧化、凝胶强度的影响。结果 迷迭香多酚提取物对羟自由基清除率最高,达到87.56%±0.28%;石榴多酚提取物对超氧阴离子的清除率最高,为86.11%±0.72%;葡萄多酚对脂氧酶抑制率最高,为89.04%±2.01%。新鲜鱼糜丙二醛含量为(0.18±0.01)mg/kg,冻藏3d后,急剧增加至(0.54±0.04) mg/kg;葡萄多酚抑制鱼糜氧化效果最好,鱼糜丙二醛含量为(0.23±0.02) mg/kg。添加姜黄多酚的冻藏未漂洗鱼糜冻融后的凝胶强度最高,为1049.85 g·mm。葡萄多酚和姜黄多酚比例为1:1时,未漂洗鱼糜丙二醛含量最低,为(0.21±0.02) mg/kg;凝胶强度最高,为(1249.97±13.31) g·mm。结论 葡萄多酚和姜黄多酚比例为1:1的多酚混合物是较好的冻藏未漂洗鱼糜保鲜剂。     

湖南省森林植物园杜鹃专类园景观营建研究

[目的]杜鹃花作为中国的传统名花之一,在我国古典园林及世界园林上有着举足轻重的地位,研究杜鹃专类园的景观营建具有重要意义.湖南省森林植物园收集和选育的杜鹃花表型多样,特色鲜明.杜鹃园的景观营建改造吸引更多的科研人才研究和保育杜鹃属植物,向全世界展示湖南杜鹃属植物的风采.[方法]通过了解湖南省森林植物园杜鹃园的基本概况,...     

三种不同生长调节剂对杜鹃光合特性的影响

选择三种不同生长调节剂,研究不同生长调节剂对杜鹃光合特性的影响,采用5个浓度梯度的IAA、GA 3、NAA对叶片进行喷洒处理,并进行不同时间、不同梯度的光合因子和光合-光响应曲线测定,使用叶子飘直角双曲线修正模型对光响应数据进行曲线拟合.结果表明:不同生长调节剂及浓度梯度对杜鹃植株产生的效果和影响各有差异.GA 3作为常用生长调节剂,提升净光合速率的效果优于IAA和NAA,更有利于营养物质在植株体内合成和转化,研究结果可为杜鹃花期调控技术提供参考依据.