Allosteric transcription stimulation by RNA polymerase II super elongation complex

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鸽子慢性电刺激用电极转接装置及其固定方法

慢性电极植入以及无线刺激技术被广泛应用于动物自由活动状态下的脑区功能研究。实现刺激器与脑内植入电极过渡连接的转接装置需固定在颅骨之上。鸟类特殊的骨质构造不利于转接装置的长期固定。以鸽子(Columba livia)为例设计制作了一种用于慢性运动诱导实验的9通道电极转接装置,长12.8 mm、宽9.5 mm、高5.5 mm,重0.42 g;根据鸽子颅骨特点在固定过程中对颅骨表面进行粗糙化处理增加固定时与牙科水泥的接触面积,并选取特定位点拧入螺钉进行固定,有效延长了转接装置的固定时间。经实验验证能够在鸽子头部稳定固定6个月以上,满足鸽子长期运动诱导研究的需求,未对动物正常活动产生影响。该装置及其固定方法亦可为其他小型动物的脑区功能研究提供借鉴。     

基于边界分析的民营医院发展问题的探析和启示

采用文献边界分析,形成问题系统并进行边界分析。基于问题视角,指出解决问题的思路包括需完善政府和民营医院对其发展定位和管理,重塑医院品牌等。基于研究视角,指出民营医院的研究需与实践紧密配合,考虑研究设计的合理性和策略措施的可操作性等。     

Highly Conductive,Light Weight,Robust, Corrosion‐Resistant,Scalable, All‐Fiber Based Current Collectors for Aqueous Acidic Batteries

Lithium‐ion batteries (LIBs) are integral parts of modern technology, but can raise safety concerns because of their flammable organic electrolytes with low flash points. Aqueous electrolytes can be used in LIBs to overcome the safety issues that come with organic electrolytes while avoiding poor kinetics associated with solid state electrolytes. Despite advances in aqueous electrolytes, current collectors for aqueous battery systems have been neglected. Current collectors used in today's aqueous battery systems are usually metal‐based materials, which are heavy, expensive, bulky, and prone to corrosion after prolonged use. Here, a carbon nanotube (CNT)–cellulose nanofiber (CNF) all‐fiber composite is developed that takes advantage of the high conductivity of CNT while achieving high mechanical strength through the interaction between CNT and CNF. By optimizing the CNT/CNF weight ratio, this all‐fiber current collector can be made very thin while maintaining high conductivity (≈700 S cm^?1) and strength (>60 MPa), making it an ideal replacement for heavy metal current collectors in aqueous battery systems.     

Combined action of static and alternating magnetic fields on ionic current in aqueous glutamic acid solution

Combined parallel static and alternating magnetic fields cause a rapid change in the ionic current flowing through an aqueous glutamic acid solution when the alternating field frequency is equal to the cyclotron frequency. The current peak is 20-30% of the background direct current. The peak is observed with slow sweep in the alternating magnetic field frequency from 1 Hz-10 Hz. Only one resonance peak in the current is observed in this frequency range. The frequency corresponding to the peak is directly proportional to the static magnetic field. The above effect only arises at very small alternating field amplitude in the range from 0.02 μT-0.08 μT. Bioelectromagnetics 19:41–45, 1998. © 1998 Wiley-Liss, Inc.     

Effect of cold stimulation during slow-wave sleep on sleep cycle

To clarify the effect of cold stimulation during slow-wave sleep (SWS) on the sleep cycle, we conducted a sleep experiment. Five healthy males slept on a bedding system we developed to make the inside of bedding cooler. When the subject was sleeping deeply in the second and fourth SWS, the system cooled their bedding. When the subject's sleep condition shifted toward arousal, the cold air was stopped. As a result, all subjects’ sleep stage shifted to light sleep and reached arousal. After stopping stimulation, they immediately returned to the SWS at the first stimulation. But at the second stimulation, the sleep state did not return to the SWS.     

Enhancement of shikonin production in single- and two-phase suspension cultures of Lithospermum erythrorhizon cells using low-energy ultrasound

This work demonstrates the use of low-energy ultrasound (US) to enhance secondary metabolite production in plant cell cultures. Suspension culture of Lithospermum erythrorhizon cells was exposed to low-power US (power density < or = 113.9 mW/cm(3)) for short periods (1-8 min). The US exposure significantly stimulated the shikonin biosynthesis of the cells, and at certain US doses, increased the volumetric shikonin yield by about 60%-70%. Meanwhile, the shikonin excreted from the cells was increased from 20% to 65%-70%, due partially to an increase in the cell membrane permeability by sonication. With combined use of US treatment and in situ product extraction by an organic solvent, or the two-phase culture, the volumetric shikonin yield was increased more than two- to threefold. Increasing in the number of US exposures during the culture process usually resulted in negative effects on shikonin yield but slight stimulation of shikonin excretion. US at relatively high energy levels caused slight cell growth depression (maximum 9% decrease in dry cell weight). Two key enzymes for the secondary metabolite biosynthesis of cells, phenylalanine ammonia lyase and p-hydroxybenzoic acid geranyltransferase, were found to be stimulated by the US. The US stimulation of secondary metabolite biosynthesis was attributed to the metabolic activity of cells activated by US, and more specifically, the defense responses of plant cells to the mechanical stress of US irradiation.     

Purification of betulinic acid from Eugenia florida (Myrtaceae) by high-speed counter-current chromatography

A high yield of betulinic acid (up to 17% from the ethanolic extract) was found in the leaves of Eugenia florida collected in south-eastern Brazil, making this species a potential commercial source of the title compound. Extracts of E. florida were subjected to solvent partition, and rapid high-speed counter-current chromatography (HSCCC) was applied to the semi-crude extracts to afford betulinic acid in high purity. The mobile and stationary phases were derived from the two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (10:5:2.5:1). The developing solvent system (stationary and mobile phases) for optimum HSCCC separation was chosen by dissolving the fraction to be chromatographed in the proposed solvent mixture and determining the amount of betulinic acid in each phase by densitometric TLC. Purified betulinic acid was characterized by 13C-NMR, GC-MS and co-injection of its methyl ester with standards in GC-FID. The HSCCC technique is commonly employed to isolate triterpene glycosides, but is applied in this study to an aglycone.