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采用空气等离子体对聚丙烯微孔膜进行表面改性,用X射线光电子能谱,扫描电镜表征膜表面形态和微观结构的变化。考察了改性膜的水接触角、水通量以及在浸没式膜-生物反应器中的动态抗污染性能力。结果表明,改性后聚丙烯微孔膜的水接触角从100°减小到40°,膜的水通量提高,污染率下降。改性后聚丙烯微孔膜的亲水性和抗污染能力得到较大提高。 相似文献
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以混酸氧化的方法对多壁碳纳米管(MWCNTs)进行改性,利用不同的回流时间来探讨含氧官能团对复吸性能的影响。采用扫描电子显微镜、BET氮吸附法对MWCNTs结构进行表征,用傅里叶变换红外光谱(FITR)、化学滴定法来测定其表面官能团。结果表明,混酸氧化使MWCNTs引入了大量的羧基等活性官能团,氧化碳纳米管(O-MWCNTs)在水中的相容性和分散性较好,两端端口被打开,孔隙结构发生变化。氧化回流1.5 h使MWCNTs表面引入最多的含氧官能团,此时OMWCNTs获得最高的平衡复吸水含量(493%),复吸性能曲线与含氧官能团的量呈现一定的正相关性,表明含氧官能团是影响复吸性能的重要因素。 相似文献
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为了提高亲水棉织物分离速度、分离效果及增加重复使用次数,采用简单的两步法对亲水棉织物进行表面改性,即先用没食子酸(Gallic acid)和硫酸铜(CuSO4)在棉织物表面形成GA-Cu(Ⅱ)络合物改性层,再用十八胺进一步修饰,制备疏水改性棉织物。利用全反射红外光谱对改性后棉织物进行表征,并通过测试改性后棉织物与去离子水的静态接触角来评价其疏水性能。结果表明：在本研究范围内的最佳实验条件为没食子酸浓度12.8 mg/mL、硫酸铜浓度10.0mg/mL、十八胺浓度8.0 mg/mL,室温下反应4.0 h,改性棉织物与去离子水的接触角为140.9°;改性后棉织物可用于植物油/水混合物和机油/水混合物的分离,分离速度快,效果好,可以多次重复使用。 相似文献
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以聚丙烯腈基活性炭纤维(PAN-ACF)为吸附剂,分别进行空气热氧化、硝酸浸渍、过氧化氢浸渍改性处理,对改性处理的PAN-ACF样品进行表征,包括SEM表面形态、比表面积BET、傅里叶变换红外线光谱(FTIR)表面基团以及总表面酸性基团;研究对痕量六价铬的吸附效果,分析PAN-ACF改性对吸附容量的影响。经过过氧化氢浸渍改性处理的ACF3炭微晶尺度变小,导致结构无序化,较大地提升了比表面积,但表面含氧官能团增势不明显;其对微污染水中六价铬的吸附效果最佳,吸附等温线相对于Langmuir方程,更符合Freundlich方程。 相似文献
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为了提高褐煤的品质,改善其应用性能,采用NaOH溶液对锡林浩特白音华褐煤(XL)和神东褐煤(SD)进行处理。利用接触角测定仪表征了原煤和处理后煤样的表面润湿性;复吸水实验及不同相对蒸汽压下的平衡含水量表征了原煤和处理煤的持水性能,并通过测定碱溶物的含氧官能团种类和含量,分析了NaOH处理前后褐煤持水性能改变的原因。研究结果表明:NaOH处理使XL和SD接触角分别增加了35.8°和43.7°,煤样的疏水性能增强;碱溶解破坏了煤中的含氧官能团,使煤样复吸水能力减弱,从而达到了提质的目的。另外,NaOH处理对煤的平衡含水量影响随着相对蒸汽压的变化而变化。 相似文献
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《滨州学院学报》2020,(4):59-64
在直流电源的激励下,利用等离子体喷枪阵列之间的相互作用,在大气压环境中产生了大尺度等离子体刷。随着电源输出电压的增加,首先在喷枪的下游形成两个分离的等离子体羽,而后分离的等离子体羽会变成一个大尺度等离子体刷。等离子体刷的长度会随着电源输出电压的增加或者空气流速的增加而变长。此外,等离子体刷的温度比较低,最大温度只有80℃左右。对于分离的等离子体羽,气隙电压不随时间变化,放电电流是间歇性的脉冲;而对于等离子体刷,气隙电压和放电电流都是周期性的脉冲。高速录像显示,等离子体刷源于两个分离的羽,之后分离的羽合并形成一个拱形的微放电丝,微放电丝处于辉光放电机制并且在气流的作用下向下游移动直到最后熄灭。 相似文献
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以聚乙烯吡咯烷酮为保护剂,制备三角形银纳米粒子溶胶。用紫外灯对三角形银纳米粒子溶胶进行光诱导实验。利用透射电子显微镜、紫外-可见吸收光谱和拉曼光谱仪研究了不同光照时间下的银胶纳米粒子的光谱特性和表面形貌,以PATP为探针分子检测银胶纳米粒子的表面增强拉曼散射光谱。实验结果表明：随着光照时间的增多,银纳米粒子溶胶颜色变化显著;紫外-可见吸收光谱吸收峰出现＂蓝移＂;透射电子显微镜图显示银纳米粒子由三角形逐渐转变成截角三角形银纳米粒子、球形银纳米粒子;表面增强拉曼散射的增强效应随着光照时间的变化逐渐减小。 相似文献
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李华静 《咸阳师范学院学报》2012,27(2):31-34
用改良的Hummer法制备了氧化石墨烯并对氧化石墨烯在溶液及玻璃表面进行了组装。采用傅里叶红外光谱(FT-IR)、热重分析(TGA)、电阻率仪、紫外可见分光光度计(UV-Vis)对氧化石墨烯及组装体系进行了表征,并用扫描电子显微镜对组装后物质的表面进行了观察。FT-IR测试表明氧化石墨烯含有羟基、羧基、环氧以及羰基等含氧官能团。UV-Vis测试表明粒径和溶剂的pH对氧化石墨烯在液相中分散性的影响。TGA测试进一步证明了氧化石墨烯含有大量含氧官能团。SEM观察揭示了石墨烯组装体的微观形貌。 相似文献
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Résumé De manière générale, l'évidence sensorielle et, plus particulièrement, visuelle constitue pour les étudiants le principal fondement du savoir scientifique: nul besoin de supposer pour connaître, tout est donné ou presque. Du point de vue de l'enseignement des sciences, cette croyance à saveur réaliste est particulièrement critique, notamment parce qu'elle conduit à penser que les concepts, lois et théories scientifiques procèdent d'un monde de matérialités plutôt que d'un monde de modèles et de relations. Au cours d'une recherche effectuée auprès d'un groupe-classe de 35 étudiants durant douze semaines, nous avons pu observer que, pour la majorité des étudiants, la compréhension du caractère construit et consensuel du savoir scientifique était facilitée par le développement d'une métaréflexion sur leurs propres productions de connaissance et les inévitables postulats et suppositions qui les fondent. Nous avons également pu observer qu'il découle de cette activité réflexive un modèle de science qui se distingue des modèles initialement tenus par les étudiants, par le pouvoir créateur et, surtout, le pouvoir de théoriser qu'il comporte: postuler, supposer, jauger collectivement de la plausibilité des résultats plutôt qu'en appeler à une instance occulte, voilà quelques-unes des conquêtes théoriques qu'ils ont effectuées et sur lesquelles nous allons nous attarder.
Sensorial, and more specifically, visual evidence is generally regarded by students as the basis for scientific knowledge: no need to postulate to understand, all is almost or practically given. From a science-teaching standpoint, this rather realistic approach is critical and leads to the belief that scientific concepts, laws, and theories stem from a world of materiality rather than from a world of models and relationships. During a 12-week study a group of 35 college students, we observed that for the majority of them, the development of metareflection on how they produce knowledge, with the inevitable and inherent postulates and conjecture, facilitated their understanding of the constructed and consensual character of scientific knowledge. We also observed that this reflexive activity facilitated the development of a new approach to science that differed from those models previously used by the students in its creative potential and, more importantly, in the power of its theoretics: to postulate, suppose, and collectively estimate the plausibility of results rather than calling up occult instances. These and other theoretical achievements will be discussed in this paper.相似文献
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Robert L. Jackson 《Academic Questions》2007,20(4):332-346
The motivation and methodology for measuring intelligence have changed repeatedly in the modern history of large-scale student
testing. Test makers have always sought to identify raw aptitude for cultivation, but they have never figured out how to promote
excellence while preserving equality. They’ve settled for egalitarianism, which gives rise to “culturally fair” tests that
substitute vagaries for knowledge, deprive students of any real appreciation for language, and trivialize education. Robert
Jackson yearns for traditional oratorical approaches to schooling that venerate and imitate essential, time-tested masters.
Unfortunately, he writes, such an education defies measurement with today’s multiple-choice instruments.
Robert L. Jackson is associate professor of English and education at The King’s College, New York, NY 10118; rjackson@tkc.edu. 相似文献
| Robert L. JacksonEmail: |
Robert L. Jackson is associate professor of English and education at The King’s College, New York, NY 10118; rjackson@tkc.edu. 相似文献
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Jose M. Castillo Joy H. Wang Julie G. Daye Kai Zhuang Shum Amanda L. March 《Journal of educational and psychological consultation》2013,23(4):413-444
ABSTRACTProfessional development is a critical systems-level intervention thought to facilitate Response-to-Intervention (RtI) implementation. The current study examined the relations between professional development, educator outcomes, and problem-solving implementation within an RtI framework using growth curve modeling. School leadership teams from pilot schools (n = 34) participated in 3 years of training. Pilot schools also received job-embedded coaching. Comparison schools (n = 27) provided a referent group. Results indicated that problem-solving implementation increased faster at pilot schools (β = 0.10, SE = 0.05, t = 2.03, p < .05). In addition, beliefs regarding data-based decision-making (β = 0.36, SE = 0.17, t = 2.13, p < .05) and perceived problem-solving skills applied to academics (β = 0.30, SE = 0.10, t = 3.07, p < .01) positively related to implementation. Implications include the needs to further explore professional development activities and for consultants to utilize evidence-based professional development principles when supporting RtI implementation. 相似文献
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Ramya Chandrasekaran Shairah Radzi Peh Zhen Kai Preman Rajalingam Jerome Rotgans Sreenivasulu Reddy Mogali 《Anatomical sciences education》2022,15(5):850-862
Due to the modernization of the medical curriculum and technological advancements, anatomy education has evolved beyond cadaveric dissection alone. Plastination techniques, three-dimensional (3D) modeling, and 3D printing technologies have progressively gained importance. However, there are limited valid and reliable surveys to evaluate students' perceptions of these new anatomy tools. Hence, this study aimed to develop a validated instrument to measure students' learning satisfaction, self-efficacy, humanistic values, and perceived limitations of plastinated and 3D printed models. A 41-item survey (five-point Likert scale, 1 = strongly disagree to 5 = strongly agree) was administered to Year 1 undergraduate medical students following a randomized controlled crossover study that evaluated plastinated and 3D printed cardiac and neck models. Ninety-six responses were received, and a factor analysis was performed with the Kaiser–Meyer–Olkin sampling adequacy of 0.878. The confirmatory factor analysis yielded a 4-factor, 19 items model that had a good fit with the latent constructs of
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This Participatory Action Research (PAR) project worked with four active street life oriented U. S. Born African men, to document
how a community sample of street life oriented U. S. Born African men between the ages of 16–65, frame and use “street life”
as a Site of Resiliency (Payne, Dissertation, 2005; Journal of Black Psychology 34(1):3–31, 2008). Qualitative data was collected in the form of 20 individual and two group interviews. These data reveal an inter-generational,
conceptualization and use, of the term “street love” in street life oriented U. S. born African men. Also, these data reveal
that notions of “street love” extend out a critique of community professionals (e.g., community researchers/interventionists,
social workers, etc.) as being unable and unwilling to produce “real help” in the local community. Examples of street love,
revealed in the study, include the men offering advice/counsel, money or “free turkeys” during Thanksgiving to one another
as well as other members of the local community. Results support Payne’s (2005) three-dimension conceptualization of “street love”: (1) individual, (2) group and (3) communal level expressions of “street
love”.
相似文献
| Yasser Arafat PayneEmail: |
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Prevention programs often encourage sexually abused children to disclose without fully considering the potential for adverse consequences. This study examined the impact of disclosure on abuse cessation and later adult symptomatology. A clinical sample of 301 adult survivors completed the Impact of Event Scale (IES/IES-R), and the Beck Depression Inventory (BDI-II). Participants were divided into 3 groups: Nondisclosure (n = 221), Disclosure/Abuse Ended (n = 25), and Disclosure/Abuse Continued (n = 55). Multivariate analyses of covariance, adjusting for abuse characteristics (age of onset, penetration, and number of perpetrators) and other trauma exposure, revealed significant differences in psychiatric symptom severity among the three groups, Wilks’ λ = 0. 95, F (6, 584) = 2.69, p = 0.014, ηp2 = 0.03. Specifically, those in the Disclosure/Abuse Continued group scored significantly higher on the IES/IES-R Intrusion subscale (p = 0.04) and the BDI-II (p = 0.01), as compared to the Nondisclosure group. The Disclosure/Abuse Ended group did not differ significantly from the other groups. Results suggest that disclosure may be detrimental unless adequate steps are taken to ensure abuse cessation and appropriate treatment. 相似文献
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Nine limiting binaries of Al2O3-SiO2-Re2O3(Re=Nd, Sm, Gd and La) system are assessed. The binary diagrams or experimental information from Toropov, Mizuno, Aramaki,
Bondar, Rolin and Coutures are optimized with the substitutional model of Kaufman and Nesor and the approximate formula of
fusion free energy for rare earth element oxides of Wu and Pelton. The extracted Gibbs free energies of pure solid oxides
and stoichiometric phases and the solution parameters are used to estimate the corresponding binaries, liquidus surfaces and
a series of isothermal sections of four ternaries Al2O3-SiO2-Nd2O3, Al2O3-SiO2-Sm2O3, Al2O3-SiO2-Gd2O3, and Al2O3-SiO2-La2O3. In the Al2O3-SiO2-Gd2O3 system samples as fired at exact temperature with different compositions were analyzed by X-ray diffractometer and the detected
results are fitted with the calculation of isothermal sections.
Supported by State Key Lab of High Performance Ceramics and Superfine Micro-structure (9517 and 9708) 相似文献