A device to apply user-specified strains to biomaterials in culture

An apparatus was developed to apply user-specified displacements to biomaterial samples in culture. The device allowed cyclic waveforms of bandwidth 0 Hz to 20 Hz to be applied under physiologic thermal (37.5 degrees C) and [CO2] (5%) conditions. For a 0 Hz to 20 Hz bandwidth signal similar in shape to a ventricular pressure waveform, the mean displacement error was 0.26% of the full-scale output. The maximum overshoot was 0.700%. Environmental system evaluation tests demonstrated a specimen cartridge temperature of 37.20 +/- 0.15 degrees C during cyclic loading and 37.23 +/- 0.21 degrees C during static conditions. [CO2] was 5.29 +/- 0.54% during cyclic loading and 5.25 +/- 0.61% during static conditions. Laminar flow applied at the loading rod entrances to the specimen cartridge ensured the sample remained sterile during testing. As a preliminary evaluation, polyurethane samples were seeded with fetal foreskin fibroblasts and subject to intermittent cyclic displacements. Results demonstrated enhanced cell proliferation and increased [PGE2] for samples subjected to 10% strain compared with unstrained controls. A next step will be to evaluate cell response sensitivity to strain magnitude, duration, direction, and frequency. The long-term intent is to establish mechanical loading configurations that induce acceptable or adaptation-inducing responses for use in implant design and tissue engineering applications.     

Field tests of a radon progeny sampler for the determination of effective dose

A two-screen sampler (an effective dosimeter), with a collection efficiency matched to the particle size response of the radon progeny dose conversion factors (DCF), obtained from the ICRP respiratory tract model as implemented in the computer code RADEP, has been developed to assess the inhalation dose from exposure to radon progeny. In order to evaluate the performance of this sampler, the second stage of a six-stage wire screen diffusion battery was designed to operate as an Effective Dosimeter. This hybrid system allowed two methods for the determination of the radon progeny DCF. For the first method, the activity size distributions, measured using the diffusion battery, were used to obtain a size-weighted DCF. A second determination of DCF was obtained directly from the fraction collected by the Effective Dosimeter. The hybrid diffusion battery was used to measure radon progeny in the Fairy Cave, Buchan, Victoria at 20-min intervals over a 30-h period. This cave had radon concentrations exceeding 2000 Bq m(-3), with low aerosol concentration and low ventilation rates. The measurements were analysed for the radon progeny PAEC, the activity size distribution, the size-weighted DCF and the effective dosimeter collected fraction. The Effective Dosimeter DCFs were determined from the collected fraction using firstly a simple linear function and then using a more complex polynomial function to correct for residual errors. For the linear factor alone, the calculated Effective Dosimeter DCFs were on average 11% lower than the equivalent size-weighted DCF values. The agreement using the polynomial function was improved markedly, with a linear regression of the DCF yielding a fitted ratio of 0.965, with an R value of 0.99. For this study, the use of the ICRP conversion convention to estimate the occupational exposure to the tour guides working in the Fairy Cave would under estimate the effective dose by up to a factor of 2.     

C-3 Substituted Lawsonemonoximates of Holmium(III): Synthesis, Characterization, and Antimicrobial Activity

A series of five new metal complexes of Ho(III) with C-3 substituted derivatives of lawsonemonexime (2-hydroxy-1,4-naphthalenediene-1-oxime) were synthesized. The compounds were characterized by melting point, elemental analysis, IR spectroscopy and magnetic susceptibility. The antimicrobial activity of the compounds were determined by disk diffusion method and broth micro-dilution techniques using Mueller Hinton medium against the following organisms: S. aureus ATCC 6538P, Klebsiella pneumoniae, NCTC 418, Pseudomonas aeruginosa ATCC 27833, Salmonella typhimurium ATCC 23564, E. coli U 1777, E. coli HB101, Proteus morganii NCIM 2860, Providencia stuartii NCIM 2799 and Acinetobacter baumannii U 24. The chelates of Ho(III) with lawsonemonoxime and Ho(III) with 3-bromolawsonemonoxime showed a variable antimicrobial activity against all organisms tested except Pseudomonas and Klebsiella spp. S. aureus was found more sensitive to all ligands and chelates tested; but the MIC values of chelates were considerably less; thus having more antimicrobial effect.     

利用Excel函数实现教学工作量核算明细表与汇总表的关联

在高校教务部门需要对教师工作量的明细表和汇总表进行多次的核对和修正,为了保证汇总表和明细表之间数据的一致性,本文用Excel函数INDEX、MATCH和COUNTIF函数实现了汇总表对明细表不重复教师的提前,使用SUMIF函数建立了汇总表数据随明细表数据更改自动修正的表间关联性,提高了工作效率并减少了表间数据不一致性。     

工程设计质量信息的采集、辨析和处置

控制工程设计质量是实现工程建设三大控制目标的关键,其成效很大程度上取决于工程设计企业对其信息的采集、剖析和处置是否得法。目前,这一过程的重要性和迫切性愈加凸现,对于企业而言,制定具体措施、加强日常管理和规避技术风险已刻不容缓。     

Genetic algorithm-based feature selection in high-resolution NMR spectra

High-resolution nuclear magnetic resonance (NMR) spectroscopy has provided a new means for detection and recognition of metabolic changes in biological systems in response to pathophysiological stimuli and to the intake of toxins or nutrition. To identify meaningful patterns from NMR spectra, various statistical pattern recognition methods have been applied to reduce their complexity and uncover implicit metabolic patterns. In this paper, we present a genetic algorithm (GA)-based feature selection method to determine major metabolite features to play a significant role in discrimination of samples among different conditions in high-resolution NMR spectra. In addition, an orthogonal signal filter was employed as a preprocessor of NMR spectra in order to remove any unwanted variation of the data that is unrelated to the discrimination of different conditions. The results of k-nearest neighbors and the partial least squares discriminant analysis of the experimental NMR spectra from human plasma showed the potential advantage of the features obtained from GA-based feature selection combined with an orthogonal signal filter.     

低碳生态型城市：中国城市发展的战略方向

中国城市化是中国经济和社会发展的一个缩影，是本世纪人类发展的一个重要事件。中国城市化的发展速度之快，即使做为城市规划和管理者本身，也为之瞠目结舌。据保守的估计，到本世纪2025年，中国从农村转移到城市的人口将达到5亿多人。城市化的发展是经济增长、提高就业机会、脱贫温饱、文化教育普及和社会保障的主要推动力。显然，中国经济和城市的发展经验也正在被其他发展中国家所汲取。     

拉丝机塔轮轴用40Cr钢热处理工艺优化

通过正交设计探究不同调质工艺下40Cr钢的组织和力学性能的变化规律,确定拉丝机塔轮轴用40Cr钢的最佳工艺,并与断轴试样和正常试样进行对比分析。结果表明,拉丝机塔轮轴用40Cr钢最优调质工艺为850℃保温1 h淬火,630℃下保温1 h回火。在最优工艺条件下组织为具有特定位向、细小的回火索氏体和极少量铁素体,硬度为283.5 HBW,冲击韧度为211.3 J/cm2。40Cr钢硬度影响因素依次为回火温度、淬火保温时间、回火保温时间和淬火温度。组织分布不均和冷速不当是导致硬度不均匀的主要原因。40Cr钢冲击性能影响因素依次是淬火温度、回火保温时间、淬火保温时间和回火温度。断口纤维区主要为小且浅的等轴韧窝;剪切唇区主要为大且深的剪切韧窝。     

Solid-phase microextraction measurement of parent and alkyl polycyclic aromatic hydrocarbons in milliliter sediment pore water samples and determination of K(DOC) values

The U.S. Environmental Protection Agency (EPA) narcosis model for benthic organisms in polycyclic aromatic hydrocarbon (PAH) contaminated sediments requires the measurement of 18 parent PAHs and 16 groups of alkyl PAHs ("34" PAHs) in pore water with desired detection limits as low as nanograms per liter. Solid-phase microextraction (SPME) with gas chromatographic/mass spectrometric (GC/ MS) analysis can achieve such detection limits in small water samples, which greatly reduces the quantity of sediment pore water that has to be collected, shipped, stored, and prepared for analysis. Four sediments that ranged from urban background levels (50 mg/kg total "34" PAHs) to highly contaminated (10 000 mg/kg total PAHs) were used to develop SPME methodology for the "34" PAH determinations with only 1.5 mL of pore water per analysis. Pore water was obtained by centrifuging the wet sediment, and alum flocculation was used to remove colloids. Quantitative calibration was simplified by adding 15 two- to six-ring perdeuterated PAHs as internal standards to the water calibration standards and the pore water samples. Response factors for SPME followed by GC/MS were measured for 22 alkyl PAHs compared to their parent PAHs and used to calibrate for the 18 groups of alkyl PAHs. Dissolved organic carbon (DOC) ranging from 4 to 27 mg/L had no measurable effect on the freely dissolved concentrations of two- and three-ring PAHs. In contrast, 5-80% of the total dissolved four- to six-ring PAHs were associated with the DOC rather than being freely dissolved, corresponding to DOC/water partitioning coefficients (K(DOC)) with log K(DOC) values ranging from 4.1 (for fluoranthene) to 5.6 (for benzo[ghi]perylene). However, DOC-associated versus freely dissolved PAHs had no significant effect on the total "34" PAH concentrations or the sum of the "toxic units" (calculated bythe EPA protocol), since virtually all (86-99%) of the dissolved PAH concentrations and toxic units were contributed by two- and three-ring PAHs.