Preparation and elements analysis of porous fluorescent glasses

A large variety of porous fluorescent glasses were prepared and the concentration of different elements in these glasses was analyzed. The start porous glasses were soaked in a solution containing soluble salts and then heated at 650 ℃ for 3 h to decompose the salts in the pores into oxides. Fluorescent agents, such as UO3, Eu203, were impregnated into the porous glasses to prepare the fluorescent glasses. The results show that soaking is a feasible method to prepare the glass sphere with compositions distinguishable from each other and easy to be located in a complicated background. Six or more components can be impregnated together into one glass sample and the concentration of them can be analyzed accurately. UO3 and Eu203 can be impregnated into porous glass to make the glass strongly fluorescent. Higher concentration of Eu203 produces stronger fluorescence while higher concentration of UO3 reduces the fluorescence intensity because of the concentration quenching effect.     

4种不同金相组织的仿古铸铁在土壤中局部腐蚀行为的差异

为了加强铸铁文物的保护，采用动电位扫描极化、模拟闭塞电池、交流阻抗等电化学方法，以及光镜、扫描电镜等显微组织分析手段，研究了4种仿古铸铁在模拟土壤介质（0．06mol／L NaCl＋0．03mol／L Na2SO4＋0．01mol／L NaHCO3溶液）中的局部腐蚀行为，详细探讨了组织差异对仿古铸铁局部腐蚀的影响。结果表明：珠光体灰口铸铁的自腐蚀电位负移最为明显，在模拟土壤条件中裂纹和腐蚀孔洞相对其它几种仿古铸铁较多。在闭塞电池中，仿古铸铁的pH值下降，Cl^-和SO4^2-增加，仿古铸铁耐蚀性依次递减的顺序为白口铸铁、麻口铸铁、珠光体＋铁素体灰口铸铁、珠光体灰口铸铁。     

WELL-DISPERSED NANODIAMOND AQUEOUS SUSPENSIONS——PREPARATION,PROPERTIES AND APPLICATIONS

1　INTRODUCTIONAsitwassynthesizedundertheconditionofhightemperatureandhighpressure ,andowingtothecommoncharacteristicsoffinedimensionandhighsurfaceenergyofnanoscaledparticles ,nanodiamond (ND )preparedbydetonationexplosioncaneasilyformstrongaggregates WhenNDpowderwasaddedinaqueousmedia ,obviousaggregationandsedimentationcanbeobserved ,whichimpairsitscharacteristicsasananometerparticle ,andthushindereditsapplication Inthiscase ,stabledispersionofNDinaqueousmediaisofgreatimportance[1 4 ] …     

HA—微孔钛基涂层种植体的复合强度

研究了羟基磷灰石(HA)和中性玻璃(G)的混合涂料在TC4多孔钛基体上的界面复合强度。探讨了中性玻璃含量、基体表面状态以及烧结工艺对这种涂层复合种植体的复合强度的影响。指出:复合的实质是中性玻璃与基体的润湿结合,最合适的玻璃含量为50 wt%,提高复合强度的关键,在于基体表面的TiN蒸镀处理,当TiN厚度为2～3 μm时,复合强度可达7.2 MPa。最佳烧结工艺为:900～950℃/30 min。     

铜石墨材料抗弯强度与孔隙的关系

定性地分析了孔隙含量、形状及其不同的位向关系在材料断裂过程中的行为，采用灰色系统方法处理试验数据，由此建立抗弯强度σｂｂ与孔隙度θ间的数学方程：σｂｂ＝σ０ｅ－βθ，式中σ０为材料孔隙度θ趋近于零时的归算抗弯强度值，β为表征孔隙形状及其位向关系的特征指数。所建立的方程式与实验值吻合较好。     

选矿厂细磨磨矿介质的选择及研究

介绍、分析研究了选矿厂细磨中的磨矿介质选择的方法。从磨矿介质的尺寸、形状、材质 3个方面 ,进行了理论研究和实验验证 ,提出了一个可行的方案。     

College students and risk-taking behaviour on Twitter versus Facebook

The propensity of college students to post content that they know may be unacceptable to future employers or other authority figures has been well established. Yet research on this topic has tended to focus exclusively on Facebook, which is problematic for two reasons. First, many young social media users are shifting away from Facebook and towards Twitter and other services. Second, college students have changed their use of social media over time and may now be more cautious about what they post on Facebook. To address this issue, a survey-based field study was conducted to compare student comfort levels with authority figures viewing their Facebook and Twitter accounts. Specifically, undergraduate business students attending a large university in the midwest of the USA were surveyed about their Facebook and Twitter accounts. Findings indicate that college students are markedly less comfortable with authority figures viewing their Twitter accounts. Paradoxically, a great majority of the study respondents were found to have public Twitter accounts, while only a very small minority have public Facebook accounts. This finding suggests that students perceive less risk on Twitter versus Facebook or that they are writing to different imagined audiences on the two platforms. Implications include the need for further inquiry and an awareness of educators and human resources professionals about students’ current social media practices.     

Adoption of travel information in user-generated content on social media: the moderating effect of social presence

Travel patterns have gradually changed from group travel to individual travel. An increasing number of people acquire travel information through various types of media. One of the alternative information sources is social media, which enables users to exchange information among members. However, one of the characteristics of social media is information sharing, not information search, which involves both giving (i.e. posting) and taking (i.e. selective reading, forwarding, replying, linking, and liking) information. Compared to the ‘giving’ side of information-sharing research, less effort has been spent on the ‘taking’ side of information research. Therefore, we investigate travel information adoption in social media as well as how individuals communicate with each other. We use the elaboration likelihood model, which measures the impact of central (e.g. argument quality) and peripheral (e.g. credibility) cues on traveller information-sharing behaviour corresponding with social presence on social media. The results of an empirical analysis of 527 respondents, who were experienced in travel information adoption via social media, were examined. Our findings revealed that argument quality had a positive effect on perceived usefulness and source credibility positively affected perceived usefulness and social relationships. Perceived usefulness had a significant positive effect on social relationships. Both perceived usefulness and social relationships affected travel information adoption. Lastly, the levels of argument quality and source credibility perceived by social media members were found to differ according to the level of social presence.     

Embedded blended learning within an Algebra classroom: a multimedia capture experiment

This two‐group, pretest‐posttest, quasi‐experimental study compared secondary students' learning of Algebra II materials over a 4‐week period when identical instruction by the same teacher was delivered through either embedded blended learning (treatment group; n = 32) or a live‐lecture classroom (control group; n = 24). For both groups, instruction was delivered in a normal classroom setting. A math test and a student survey were used to measure students' learning of Algebra II and satisfaction with the instruction. Students in the treatment group showed significantly greater gains in Algebra II test scores and evaluated their learning experiences significantly more positively than did the control group. The great majority (80%) of students in the treatment group preferred the embedded blended learning over traditional live lectures for future learning of math. Students' responses to open‐ended survey questions suggested that students in the treatment group appreciated the: (a) ability to control the pace of instruction; (b) new role of the classroom teacher; (c) lack of distraction in the blended learning environment; and (d) accessibility of the embedded multimedia lessons outside the classroom. This study suggests that screen‐capture instructional technology can be used towards establishing a teacher‐based, embedded blended learning environment within a secondary algebraic classroom.     

一种视频流畅度优先的带宽自适应方法

由于现有基于平均接收质量的带宽自适应方法,在自适应过程中会出现视频质量振荡,且在可用带宽急剧恶化时会出现中断的问题,提出了一种流畅度优先的带宽自适应方法。该方法引入了图着色优先级算法,在带宽自适应过程中,在保证视频的流畅播放的前提下,通过判断是否振荡调整,改变平均质量范围,以达到减少视频振荡次数的效果。仿真结果表明,该方法在自适应调整传输速率、有效利用带宽的同时,保证了流畅度并减少视频质量振荡,符合预期目标。