The working of a pulsatory liposome

Under positive osmotic stress, a greater lipid vesicle swells to a critical diameter, when suddenly a transbilayer pore appears and grows to a maximum radius, then decreases and finally disappears. An amount of liquid was leaked out through the pore and the vesicle returns to the initial state and can start another cycle. This is a pulsatory lipid liposome. In this paper, we have considered the problem of such liposomes. We have obtained the condition that a pulsatory liposome to run an a priori settled number of cycles. The length time of each cycle and its activity life was calculated. Also, we have calculated the quantities of solute leaked out through a pore in each cycle. The pulsatory liposome may be regarded as a biotechnological device to dose drugs at fixed intervals time.     

神经芯片技术的研究进展

神经芯片是一种用硅微加工技术制造的微机电器件.活体的哺乳动物神经元细胞在神经芯片上培养存活,通过外加电路的控制,人们可以方便地对活体神经元进行检测,研究其在外加激励模式下的响应,整个研究过程是选择性的、实时的、连续的.简要评述了神经芯片技术的研究进展,并对其前景作了展望.     

新疆紫草中抗生育化学成分

从新疆紫草(Arnebia euchroma(Royle)Johnst.)的根部分得四种酚类化合物,经波谱分析,确定为rabdosiin二钾盐(dipotassium rabdosiin 1),迷迭香酸钾盐(potassium rosmarinate 2),迷迭香酸钠盐(sodium rosmarinate 3),阿魏酸钠盐(sodium ferulate 4).其中rabdosiin二钾盐具有显著的抗生育活性,而迷迭香酸钾盐、迷迭香酸钠盐和阿魏酸钠盐为首次从该植物中分离获得.     

Use of a cane for recovery from backward balance loss during treadmill walking

Purpose. To study whether a cane improved balance recovery after perturbation during walking.

Method. This study was a crossover comparison comparing the effect of walking with and without a cane for balance recovery after perturbation during treadmill walking. Five normal young volunteers participated. The velocity and acceleration of a marker sited on the seventh cerebral vertebra (C7) and vertical hand motion were measured by a motion analysis system.

Result. When using a cane, C7 backward velocity increased by approximately 15% (413 SD 95?mm/s with cane vs. 358 SD 88?mm/s without). In addition, C7 backward acceleration increased by approximately 23% (3.2 SD 0.7?m/s² with cane vs. 2.6 SD 0.8?m/s² without) and the vertical motion of the right hand decreased (187 SD 98?mm with cane vs. 372 SD 260?mm without). Additionally, no subject was able to use a cane to broaden their base of support.

Conclusions. The ability to limit trunk extension is crucial for preventing falls. Therefore, using a cane jeopardizes recovery from backward balance loss. The results encourage further research on the risk of a cane on balance recovery for the elderly population and habitual cane users.     

Direct Pressure Monitoring Accurately Predicts Pulmonary Vein Occlusion During Cryoballoon Ablation

Cryoballoon ablation (CBA) is an established therapy for atrial fibrillation (AF). Pulmonary vein (PV) occlusion is essential for achieving antral contact and PV isolation and is typically assessed by contrast injection. We present a novel method of direct pressure monitoring for assessment of PV occlusion.Transcatheter pressure is monitored during balloon advancement to the PV antrum. Pressure is recorded via a single pressure transducer connected to the inner lumen of the cryoballoon. Pressure curve characteristics are used to assess occlusion in conjunction with fluoroscopic or intracardiac echocardiography (ICE) guidance. PV occlusion is confirmed when loss of typical left atrial (LA) pressure waveform is observed with recordings of PA pressure characteristics (no A wave and rapid V wave upstroke). Complete pulmonary vein occlusion as assessed with this technique has been confirmed with concurrent contrast utilization during the initial testing of the technique and has been shown to be highly accurate and readily reproducible.We evaluated the efficacy of this novel technique in 35 patients. A total of 128 veins were assessed for occlusion with the cryoballoon utilizing the pressure monitoring technique; occlusive pressure was demonstrated in 113 veins with resultant successful pulmonary vein isolation in 111 veins (98.2%). Occlusion was confirmed with subsequent contrast injection during the initial ten procedures, after which contrast utilization was rapidly reduced or eliminated given the highly accurate identification of occlusive pressure waveform with limited initial training.Verification of PV occlusive pressure during CBA is a novel approach to assessing effective PV occlusion and it accurately predicts electrical isolation. Utilization of this method results in significant decrease in fluoroscopy time and volume of contrast.     

The Impact of Device Polarity on the Performance of Polymer–Fullerene Solar Cells

Diketopyrrolopyrrole (DPP)‐conjugated polymers are a versatile class of semiconductors for application in organic solar cells because of their tunable optoelectronic properties. A record power conversion efficiency (PCE) of 9.4% was recently achieved for DPP polymers, but further improvements are required to reach true efficiency limits. Using five DPP polymers with different chemical structures and molecular weights, the device performance of polymer:fullerene solar cells is systematically optimized by considering device polarity, morphology, and light absorption. The polymer solubility is found to have a significant effect on the optimal device polarity. Soluble polymers show a 10–25% increase in PCE in inverted device configurations, while the device performance is independent of device polarity for less soluble DPP derivatives. The difference seems related to the polymer to fullerene weight ratio at the ZnO interface in inverted devices, which is higher for more soluble DPP polymers. Optimization of the nature of the cosolvent to narrow the fibril width of polymers in the blends toward the exciton diffusion length enhances charge generation. Additionally, the use of a retroreflective foil increases absorption of light. Combined, the effects afford a PCE of 9.6%, among the highest for DPP‐based polymer solar cells.     

A patient immobilization device for prone breast radiotherapy: Dosimetric effects and inclusion in the treatment planning system

PurposeTo assess the dosimetric impact of a patient positioning device for prone breast radiotherapy and assess the accuracy of a treatment planning system (TPS) in predicting this impact.MethodsBeam attenuation and build-up dose perturbations, quantified by ionization chamber and radiochromic film dosimetry, were evaluated for 3 components of the patient positioning device: the carbon fiber baseplate, the support cushions and the support wedge for the contralateral breast. Dose calculations were performed using the XVMC dose engine implemented in the Monaco TPS. All components were included during planning CT acquisition.ResultsBeam attenuation amounted to 7.57% (6 MV) and 5.33% (15 MV) for beams obliquely intersecting the couchtop–baseplate combination. Beams traversing large sections of the support wedge were attenuated by 12.28% (6 MV) and 9.37% (15 MV). For the support cushion foam, beam attenuation remained limited to 0.11% (6 MV) and 0.08% (15 MV) per centimeter thickness. A substantial loss of dose build-up was detected when irradiating through any of the investigated components. TPS dose calculations accurately predicted beam attenuation by the baseplate and support wedge. A manual density overwrite was needed to model attenuation by the support cushion foam. TPS dose calculations in build-up regions differed considerably from measurements for both open beams and beams traversing the device components.ConclusionsIrradiating through the components of the positioning device resulted in a considerable degradation of skin sparing. Inclusion of the device components in the treatment planning CT allowed to accurately model the most important attenuation effect, but failed to accurately predict build-up doses.     

Studies on the Nucleic Acid and Protein Content in the Cotyledon Cells of Lotus Using Fluorescent Imaging System with a Scientific grade Charge Coupled Device

Enzyme dissociated cotyledon cells were obtained from red lotus ( Nelumbo sp. ) on the 5th day and 20th day after fertilization respectively. DNA, RNA and total protein content of individual 5 d and 20 d cell were measured correlatively by microfiuorescent imaging system with a cooled scientific-grade Charge coupled deviced (CCD) camera. The results showed that DNA content of the 20 day cell has become polyploidized from 4C to 8C approximately. The window analysis indicated that relative content of RNA and total protein of the 20 day cell was more than 11 times that of the 5 day cell in the same 4C DNA window respectively. The multiple in-creased of RNA and total protein content was about the same as that of DNA in 2 DNA windows (4C and 8C) of the 20 day cell. These data showed that the enormous accumulation of storage proteins in the cotyledon cells of red lotus depends on both DNA ploidy and selective expression of the subunit genes of the storage proteins during the developmental process.     

Preliminary Study on Transformation of Wheat Apical Point

Apical points of young seedlings of wheat (Triticum aestivum) cultivar "Jing 411” and somatic calli of cultivar "FK8” were transformed with plasmids pBI121 and (or) pBIAH-A+ by using microprojectile bombardment. Histochemical assay of GUS activity showed positive reaction on some of the transformation processed apical points and calli. This demonstrated that foreign genes were introduced into the apical meristematic cells as well as the callus cells. The plantlets of cv. "Jing 411” survived after apical point transformation with pBIAH-A+ were transplanted into the field and the progenies were screened with kanamycin. 4 % of the screened seeds germinated into green seedlings with kanamycin resistance. Dot hybridization of total DNA from kanamycin resistant plants showed the existence of foreign DNA in some of the detected plants.     

生物学实验中的湿度控制：改良的装置及工作原理

相对湿度是生物学实验中一个十分重要而又较难准确控制的环境因素．本项研究设计出一种改进的简易控湿装置,可利用普通温光型培养箱同时进行不同湿度水平的生物学实验．该装置由微型气泵、３个试剂瓶串连而成的三联体和一个用有机玻璃制成的生长箱组成,经在２０℃下对饱和酒石酸钠溶液调节的湿度（理论值９２％）连续测定和校正,控湿效果良好,误差仅±１％左右．同时对不同浓度硫酸溶液控制生长箱内不同水平的湿度进行了测定和检验,亦效果良好,且对环境温度的适应性强,在５～３５℃范围内同一硫酸浓度控制相同的稳定湿度．最后,对上述装置控制湿度的稳定性及其影响因素进行了讨论