100～700 mL液体培养基的微波灭菌效果观察

为研究家用微波炉对少量液体培养基的灭菌效果,对100 -700 mL液体培养基采取微波分别进行灭菌,测定其灭菌时间,并对达到灭菌效果的培养基通过接种不同细菌进行质检.结果显示100、200、300、400、500、600、700 mL液体培养基分别在4.5、5.0、7.0、9.0、12.0、19.0、25.0 min达到最有效的灭菌效果.室温保存15 d仍无细菌生长.枯草杆菌黑色变种芽胞菌测试无菌生长.金黄色葡萄球菌、大肠埃希菌及普通变形杆菌在液体培养基里的生长现象、特种后细菌的菌落和形态染色特征及其生化反应均无明显差异.实验表明2 450 MHz,700 W的微波炉对100 - 700 mL的液体培养基不但能快速达到有效的灭菌效果,且营养成分不会被破坏.     

Influence of 864 MHz electromagnetic field on growth kinetics of established cell line

Considering often contradictory data on biological effects of mobile phones frequencies on established cell culture lines, our study aimed at evaluating the influence of 864 MHz electromagnetic field on proliferation, colony forming ability and viability of Chinese hamster lung cells continuous line V79. Prior to exposure for 1, 2 and 3 hours in transversal electromagnetic mode cell (TEM-cell) equipped by Philips PM 5508 signal generator cell samples were sub-cultivated for one day. Cell samples were exposed to 864 MHz continuous wave at an average specific absorption rate (SAR) of 0.08 W/kg. To determine cell growth, V79 cells were plated in concentration of 1 × 10⁴ cells per milliliter of nutrient medium RPMI 1640, and raised in a humified atmosphere at 37°C in 5% CO₂. Cell proliferation was determined by cell counts for each hour of exposure on post-exposure day 1, 2, 3, 4 and 5. To identify colony-forming ability, cells were cultivated in concentration of 40 cells/mL of RPMI 1640 and incubated according to the deliberated experimental protocol. Colony forming ability for each hour of exposure was defined by colony counts on experimental day 7. Trypan blue exclusion test was used to determine viability of cells. In comparison to sham-exposed cells, growth curve of irradiated cell samples showed significant decrease (p < 0.05) after 2 and 3 hours of exposure on experimental day 3, respectively. Both, the colony forming ability and viability of irradiated cells did not significantly differ from exposed “mock” condition. Under strictly controlled laboratory conditions, applied radiofrequency microwaves (RF/MW) irradiation significantly affected cell proliferation kinetics but not viability or ability of V79 cells to form colonies. Sophisticated mechanism of action is intending to be elucidated in the further research which will include insight into the RF/MW related event at the subcellular level.     

Non-invasive determination of plant biomass with microwave resonators

Non-invasive and rapid determination of plant biomass would be beneficial for a number of research aims. Here, we present a novel device to non-invasively determine plant water content as a proxy for plant biomass. It is based on changes of dielectric properties inside a microwave cavity resonator induced by inserted plant material. The water content of inserted shoots leads to a discrete shift in the centre frequency of the resonator. Calibration measurements with pure water showed good spatial homogeneity in the detection volume of the microwave resonators and clear correlations between water content and centre frequency shift. For cut tomato and tobacco shoots, linear correlations between fresh weight and centre frequency shift were established. These correlations were used to continuously monitor diel growth patterns of intact plants and to determine biomass increase over several days. Interferences from soil and root water were excluded by shielding pots with copper. The presented proof of principle shows that microwave resonators are promising tools to quantitatively detect the water content of plants and to determine plant biomass. As the method is non-invasive, integrative and fast, it provides the opportunity for detailed, dynamic analyses of plant growth, water status and phenotype.     

Preparation of inulin and phenols-rich dietary fibre powder from burdock root

The simultaneous ultrasonic/microwave assisted extraction (UMAE) of inulin and production of phenols-rich dietary fibre powder from burdock root was studied. It was found that UMAE required a much shorter extraction time than conventional stirring extraction. And the recovery of inulin increased with the increase of microwave power as well as solvent to solid ratio. A comparison of scanning electron microscopy images of raw and simultaneous ultrasonic/microwave treated burdock root indicated microfractures and disruption of cell walls in burdock root flakes. The dietary fibre powder prepared from the residue of burdock root after inulin extraction was rich in phenols (302.62 mg GAE/100 g powder). The results showed that drying temperature in the selected range did not significantly affect the hydration properties. The relatively high water retention capacity, swelling capacity and oil-holding capacity of the dietary fibre powder indicated its broad use as a modifier of properties of formulated products.     

茶皂素光波干法提取与产品开发

本文考察茶皂素的微波光波组合无溶剂提取方法,发现微波光波提取干法不用溶剂,仅用微量的DMF作为能量传递介质,提取速度是传统提取方法的1800倍以上,成本明显降低.利用高倍FM、IR等手段对微波提取机理进行初步研究,从微波对植物组织结构的影响上阐明次生代谢产物的微波提取机理.利用提取的茶皂素开发成洗发香波,对多个配方进行了多方面的性能评价,其中两个配方的多项指标达到或优于国家标准.     

银杏叶总黄酮的超声波提取法

本文通过单因素实验和正交实验,确定了超声波法提取银杏叶中黄酮类化合物的最佳提取工艺,并与常规乙醇浸提法,微波提取法作了比较研究。实验表明：超声波提取法优于常规乙醇浸提法和微波提取法。超声波法的最佳操作条件为：320W超声波功率,温度30℃,70％乙醇,在液固比15：1条件下提取10min,连续提取2次,总黄酮提取率可达94．1％。     

微波辅助提取灰树花多糖工艺研究

采用提取时间、微波功率、液料比的单因素试验和正交试验法优化微波辅助提取灰树花多糖条件.结果表明,以净多糖得率为指标,影响微波辅助提取灰树花多糖的主次因素为:提取时间＞微波功率＞液料比,并且提取时间和微波功率的影响达到了极显著水平.灰树花多糖最佳提取工艺条件为:提取时间为10 min,微波功率为80%(全功率为800 W),液料比为25∶1.创立了一种用苯酚-硫酸法测定多糖时排除蛋白质干扰的方法.     

Short‐term exposure to a 1439‐MHz TDMA signal exerts no estrogenic effect in rats

The aim of this study was to elucidate the possible effects of short‐term exposure to a 1439‐MHz electromagnetic field (EMF) employing time division multiple access (TDMA), which is the basis of the Japanese Personal Digital Cellular system, on estrogenic activity in rats. Sixty‐four ovariectomized female Sprague–Dawley rats were divided into four groups: EMF exposure (EM), sham exposure, cage control, and 17 beta‐estradiol injected (E2). The EM group was exposed, for 4 h per day on three consecutive days, to the 1439‐MHz TDMA signal that produced 5.5–6.1 and 0.88–0.99 W/kg average specific absorption rates in the brain and the whole body, respectively. The uterine wet mass and serum estradiol level significantly increased in the E2 group, while there were no differences among the other three groups. Although negative effects of long‐term EMF exposure must be thoroughly investigated before a final conclusion can be reached, our results do not support the assumption that the high frequency EMF used in cellular phones exerts estrogenic activity. Bioelectromagnetics 31:573–575, 2010. © 2010 Wiley‐Liss, Inc.     

塔拉豆荚壳中单宁的提取-微波辅助萃取法

利用微波辅助萃取技术对塔拉单宁进行提取,通过不同的起始温度、加蒸馏水量、提取次数、功率大小等实验并用1%的FeCl3溶液检测提取效果,确定较佳的提取温度、次数、加蒸馏水量和微波辅助萃取仪的功率等因素。结果表明,微波提取塔拉单宁的最佳提取条件为:每次提取加水150~200 mL,微波功率400 w,60℃提取20 min,反复提取4次;再升温至70℃提取20 min 2次,即可提取完全。原料中的单宁含量微波浸提比水浴锅浸提稍高。因此认为用此提取方法可替代水浴浸提法。