巧妙隐藏邮件地址

最近作了一个Blog,为了让网友联系方便,特意在网页上留下了电子邮件地址。可是却发现垃圾邮件越来越多,原来很多邮件地址都是靠一种邮件地址收集器的软件自动搜索网页中如电子邮件格式字符串而得到的,所以会收到无穷无尽的垃圾邮件了。怎么避免这种情况呢?最近笔者发现的一款小     

短信平台移动QQ

“移动QQ”服务是腾讯科技有限公司与移动通信运营公司合作推出，使移动电话用户可以用短信功能、WAP功能和QQ用户进行短讯通信的一种服务。它与KJavaQQ相比，使用条件要相对简单点，不需要手机支持KJava，也不要求手机有上网功能，只要用户手机可以正常收发短信即可，这无疑为喜欢聊天而手机又不支持KJavaQQ的用户提供了很好的一种方式。要使用移动QQ也很简单，只需要有一部可正常收发中文短信的手机即可，如果你没有QQ号码，还可以用手机短信再申请一个QQ号码，并且短信平台的移动QQ使用起来与KJava相差无几。     

污水COD超标的影响因素及解决措施

通过对总排污口污水中主要还原性物质逐项进行掩蔽,分析掩蔽前后污水COD值的变化,找出了影响COD的主要因素并提出了改进措施,使排污总口COD值大幅降低。     

Detection of probe dither motion in near-field scanning optical microscopy

The probe-to-sample separation in near-field scanning optical microscopes can be regulated by a noncontact shear-force sensing technique. The technique requires the measurement of a minute dither motion applied to the probe. We have characterized an optical detection method for measuring this motion to determine the optimum detection configuration in terms of sensitivity and stability. A scalar diffraction model of the detection method is developed for calculating sensitivity, and experimental results are found to be in good agreement with the theoretical predictions. We find that maximum sensitivity and stability cannot be achieved simultaneously, and it may be desirable in practice to trade sensitivity for enhanced stability.     

Tunable single frequency thulium:YAG microchip laser with external feedback

By use of the reflection of an uncoated external etalon, a diode-pumped thulium-doped YAG microchip laser was forced into a single-frequency mode. The wavelength of the single-frequency radiation was tunable over 15 nm simply by translation of the etalon relative to the laser. Output powers of 45 mW were achieved in a monolithic setup that is insensitive to vibrations. The origin of the single-frequency oscillation is the wavelength-dependent reflection of the etalon, which is coupled back into the laser resonator. This method permits the combination of inherently stable, single-frequency resonator geometries such as microchips with laser materials that have broad tuning ranges.     

Molecular mechanism for the effects of trehalose on beta-hairpin folding revealed by molecular dynamics simulation

Recent work has shown that trehalose can facilitate and inhibit protein folding, but little is known about the molecular basis of these effects. Molecular-level insights into how the osmolyte affects protein folding are of significance for the rational design of small molecular additives for enhancing or hindering the folding of proteins. To investigate the molecular mechanisms of the facilitation and inhibition effects of trehalose on protein folding, molecular dynamics (MD) simulation of a beta-hairpin peptide (Trp-Arg-Tyr-Tyr-Glu-Ser-Ser-Leu-Glu-Pro-Glu-Pro-Asp) in different trehalose concentrations (0-0.26 mol/L) is performed using an all-atom model. It is found that at a proper trehalose concentration (0.065 mol/L), the peptide folds faster than that in water, but it cannot fold to the beta-hairpin at higher trehalose concentrations. Free energy landscape analysis indicates the presence of three intermediate states in both pure water and in 0.065 mol/L trehalose, but the potential energy barriers in the folding pathway decrease greatly in 0.065 mol/L trehalose, so the peptide folding is facilitated. Moreover, at this trehalose concentration, there is a favorable balance between the peptide backbone hydrogen bonds (H-bonds) and the peptide-trehalose H-bonds, leading to the stabilization of the folded peptide. At higher trehalose concentrations, however, trehalose molecules cluster in the peptide region and interact with the peptide via many H-bonds that prevent the peptide from folding to its native structure. The energy landscape analysis indicates that the potential energy barriers increase so greatly that the peptide cannot overcome it, getting trapped in a local free energy basin. The work reported herein has elucidated the molecular mechanism of the peptide folding in the presence of trehalose.     

The medial scaffold of 3D unorganized point clouds

We introduce the notion of the medial scaffold, a hierarchical organization of the medial axis of a 3D shape in the form of a graph constructed from special medial curves connecting special medial points. A key advantage of the scaffold is that it captures the qualitative aspects of shape in a hierarchical and tightly condensed representation. We propose an efficient and exact method for computing the medial scaffold based on a notion of propagation along the scaffold itself, starting from initial sources of the flow and constructing the scaffold during the propagation. We examine this method specifically in the context of an unorganized cloud of points in 3D, e.g., as obtained from laser range finders, which typically involve hundreds of thousands of points, but the ideas are generalizable to data arising from geometrically described surface patches. The computational bottleneck in the propagation-based scheme is in finding the initial sources of the flow. We thus present several ideas to avoid the unnecessary consideration of pairs of points which cannot possibly form a medial point source, such as the "visibility of a point from another given a third point and the interaction of clusters of points. An application of using the medial scaffold for the representation of point samplings of real-life objects is also illustrated     

Improving metastable impact electron spectroscopy and ultraviolet photoelectron spectroscopy signals by means of a modified time-of-flight separation

The separation of ultraviolet photoelectron spectroscopy (UPS) and metastable impact electron spectroscopy (MIES) is usually performed by a time-of-flight (ToF) separation using pre-set ToF for both types of signal. In this work, we present a new, improved ex situ signal separation method for the separation of MIES and UPS for every single measurement. Signal separation issues due to changes of system parameters can be overcome by changing the ToF separation and therefore allowing for the application of a wider range of measuring conditions. The method also enables to identify and achieve separation of the two signals without any time consuming calibration and the use of any special material for the calibration. Furthermore, changes made to the discharge source are described that enable to operate an existing MIES/UPS source over a broader range of conditions. This allows for tuning of the yield of UV photons and metastable rare gas atoms leading to an improved signal to noise ratio. First results of this improved setup are well in agreement with spectra reported in literature and show increased resolution and higher signal intensities for both MIE and UP spectra compared to the previous, non-optimized setup.     

2005年优秀通讯员

721型分光光度计的钨灯稳压电源电路如图1所示。     

Isolation of Yersinia from raw meat (pork and chicken) and precooked meat (porcine tongues and sausages) collected from commercial establishments in Mexico City

A total of 160 meat product samples were collected from commercial outlets in Mexico City to investigate the presence of different species of Yersinia by the 4 degrees C enrichment method after 1, 3, 5, and 7 days of incubation using alkaline treatment and isolating in cefsulodin-Irgasan-novobiocin and MacConkey agars with Tween 80. Overall, Yersinia spp. were isolated from 27% of the samples analyzed, whereas 40% of the raw and only 13% of the precooked samples were contaminated. Although 2,970 colonies showed Yersinia characteristics, only 706 (24%) actually corresponded to this genus: 49% were Yersinia enterocolitica, 25% Yersinia kristensenii, 15% Yersinia intermedia, 9% Yersinia frederiksenii, and 2% Yersinia aldovae; 10% corresponded to biotype 2, 2% to biotype 3, and 4% to biotype 4. The presence of Yersinia in raw and cooked meat products represents a health risk for consumers in Mexico, where further clinical studies are needed to assess the epidemiological importance of this pathogen.