Optimal combination of electrodes and conductive gels for brain electrical impedance tomography

Background

Electrical impedance tomography (EIT) is an emerging imaging technology that has been used to monitor brain injury and detect acute stroke. The time and frequency properties of electrode–skin contact impedance are important for brain EIT because brain EIT measurement is performed over a long period when used to monitor brain injury, and is carried out across a wide range of frequencies when used to detect stroke. To our knowledge, no study has simultaneously investigated the time and frequency properties of both electrode and conductive gel for brain EIT.

Methods

In this study, the contact impedance of 16 combinations consisting of 4 kinds of clinical electrode and five types of commonly used conductive gel was measured on ten volunteers’ scalp for a period of 1 h at frequencies from 100 Hz to 1 MHz using the two-electrode method. And then the performance of each combination was systematically evaluated in terms of the magnitude of contact impedance, and changes in contact impedance with time and frequency.

Results

Results showed that combination of Ag⁺/Ag⁺Cl^? powder electrode and low viscosity conductive gel performed best overall (Ten 20^® in this study); it had a relatively low magnitude of contact impedance and superior performance regarding contact impedance with time (p?<?0.05) and frequency (p?<?0.05).

Conclusions

Experimental results indicates that the combination of Ag⁺/Ag⁺Cl^? powder electrode and low viscosity conductive gel may be the best choice for brain EIT.

     

几种海洋微藻的氨基酸含量

分析测定分属硅藻,绿藻和蓝藻的７种海洋饵料微藻氮和氨基酸含量。氮含量范围为４．０４％～９．８６％,总氨基酸中共测出１７种氨基酸,含量范围为１．２３％～９．７４％。名藻的总氨基酸含量顺序与氮含量相同     

蚜虫性信息素田间引诱雄性桃蚜研究(英文)

据报道许多蚜虫性信息素的主要成分是（＋）-（1R,4aR,7S,7aR）-荆齐醇和（＋）－（4aS,7S,7aR）-荆芥内酯。应用这两种物质在1995年和1996年进行引诱桃蚜MyzusPersicae雄蚜的田间试验,在桃园的试验中取得了良好的效果,初步摸索出田间应用最佳时间与合适的配比。     

家隅蛛的染色体（蜘蛛目：漏斗蛛科）

报告家隅蛛的染色体数目、形态结构和性染色体组成。实验结果表明:家隅蛛的染色体数目是:雄性体细胞为43,雌体为46。性别决定机制是X_1X_2X_3O型。3个(对)X染色体是全部染色体中最小的和次最小的。所有染色体几乎都是端或亚端着丝粒染色体,这一结论被对其C-显带标本的分析所证实。6~＃～14~＃染色体长臂末端有明显的结构异染色质。G-显带标本中,获得了清晰的带纹。     

血纤蛋白粘附肽与低分子量单链尿激酶融合产物活性分析

人工合成了血纤蛋白粘附肽基因,构建了粘附肽与低分子量单链尿激酶ｃＤＮＡ的融合基因,在大肠杆菌中表达了融合基因。融合基因表达产物的抗原性和天然尿激酶相同,并具有尿激酶的溶纤活性和粘附肽的抗纤维蛋白单体聚合的功能。     

The recognition of multi-class protein folds by adding average chemical shifts of secondary structure elements

The recognition of protein folds is an important step in the prediction of protein structure and function. Recently, an increasing number of researchers have sought to improve the methods for protein fold recognition. Following the construction of a dataset consisting of 27 protein fold classes by Ding and Dubchak in 2001, prediction algorithms, parameters and the construction of new datasets have improved for the prediction of protein folds. In this study, we reorganized a dataset consisting of 76-fold classes constructed by Liu et al. and used the values of the increment of diversity, average chemical shifts of secondary structure elements and secondary structure motifs as feature parameters in the recognition of multi-class protein folds. With the combined feature vector as the input parameter for the Random Forests algorithm and ensemble classification strategy, we propose a novel method to identify the 76 protein fold classes. The overall accuracy of the test dataset using an independent test was 66.69%; when the training and test sets were combined, with 5-fold cross-validation, the overall accuracy was 73.43%. This method was further used to predict the test dataset and the corresponding structural classification of the first 27-protein fold class dataset, resulting in overall accuracies of 79.66% and 93.40%, respectively. Moreover, when the training set and test sets were combined, the accuracy using 5-fold cross-validation was 81.21%. Additionally, this approach resulted in improved prediction results using the 27-protein fold class dataset constructed by Ding and Dubchak.     

竹红菌甲素对红细胞膜和几种磷脂脂质体膜的流动性的光敏损伤

本文以荧光探针为手段,通过测量膜偏振度的变化,探讨了竹红菌甲素光敏作用对红细胞膜和几种磷脂脂质体膜的流动性的损伤。结果表明,甲素光敏作用使不同种类的磷脂(DPPC,DPPC/DPPE,红细胞膜磷脂)脂质体的流动性增加,其对光敏作用的敏感程度为红细胞膜磷脂脂质体显著小于DPPC/DPPE脂质体及DPPC脂质体。对红细胞膜来说,甲素光敏作用使其流动性呈现先降低而后增加的现象。去除膜上的spectrin以及用胰蛋白酶处理可使这种流动性变化的幅度受到抑制。据此,我们认为,膜磷脂,膜蛋白对甲素光敏作用中膜流动性的变化有着不同的影响,膜蛋白,特别是spectrin,是其中极重要的因素。     

EFFECTS OF RAPE GROWN IN SO2-ENRICHED ATMOSPHERES ON PERFORMANCE OF THE APHID,MYZUS PERSICAE (SULZER) *

Abstract Performances of the aphid, Myzus persicae, were monitored during feeding on leaves of the rape, Brassica chinensis, previously fumigated with SO₂ in a range of concentrations between 20 and 160 nl/1 at 25°C. Response of the aphids depended on dose of the air pollutant. Moderate dose of SO₂ treatment on the rape greatly enhanced the aphids' performances while high level of the pollutant heavily suppressed their growth and reproduction. They performed best at about 80 nl/l SO₂, where nymphal mean relative growth rate (MRGR), adult fecundity and intrinsic increase rate(r_m) of the population increased by 31.5%, 89.8% and 42. 7% over those of control aphids, respectively. Determination of the plant chemistry suggests that the altered relative content of methionine induced by So, exposure might be responsible for this response of dosage dependence.     

松属针叶角质层微形态特征在分类学中的应用

角质层是表皮细胞壁表面的一层不透水的脂肪性物质。角质层与表皮细胞紧密结合,植物表皮细胞形态和排列方式、气孔器的形态结构等微形态特征均能在角质层上反映出来。利用光学显微镜和扫描电镜对松属（Pinus）12种植物针叶角质层微形态特征进行观察和比较,详细描述20个性状,其中12个性状来自角质层内表面,8个性状来自角质层外表面。结果表明,这些特征可为该属属下分类和相似种的鉴别提供有用信息,具有重要的分类学意义：①表皮细胞长度、表皮毛长度、角质层外表面起伏程度、表皮细胞轮廓、有无气孔塞和针絮状物质等角质层微形态特征具有自身特异性,在属下可作为松属组级水平上的分类依据。角质层微形态 特征不支持将五针松组（P. Section Cembra）和白皮松组（P. Section Parrya）合并为P. Section Quinquefolius的观点,亦不支持将油松组（P. Section Pinus）分成P. Section Pinus和P. Section Trifolius的看法。②白皮松（P. bungeana）针叶角质层微形态特征既与五针松组有相同之处,又与油松组有相似之处,还有部分特征显示出不同于松属其他种类的独特性,可为白皮松亚属（P. Subgenus Parrya）的建立提供新依据。③扫描电镜下表皮细胞垂周壁纹路,气孔塞有无和外表面气孔形状等特征可为形态相似种火炬松（P. taeda）和湿地松（P. elliottii）提供种间界定依据。     

Effects of glycoalkaloids from Solanum plants on cucumber root growth

The phytotoxic effect of four glycoalkaloids and two 6-O-sulfated glycoalkaloid derivatives were evaluated by testing their inhibition of cucumber root growth. The bioassays were performed using both compounds singly and in equimolar mixtures, respectively. Cucumber root growth was reduced by chaconine (C), solanine (S), solamargine (SM) and solasonine (SS) with IC₅₀ values of 260 (C), 380 (S), 530 (SM), and 610 μM (SS). The inhibitory effect was concentration-dependent. 6-O-sulfated chaconine and 6-O-sulfated solamargine had no inhibitory effects, which indicated that the carbohydrate moieties play an important role in inhibiting cucumber root growth. The equimolar mixtures of paired glycoalkaloids, both chaconine/solanine and solamargine/solasonine, produced synergistic effects on inhibition of cucumber root growth. By contrast, mixtures of unpaired glycoalkaloids from different plants had no obviously synergistic effects. The growth inhibited plant roots lacked hairs, which implied that inhibition was perhaps at the level of root hair growth.