Spectroscopic and chromatographic studies of sculptural polychromy in the Zhongshan Grottoes (R.P.C.)

The sculptural polychromy in the Zhongshan Grottoes, sited in northwest China, has been investigated in terms of chemical composition of employed materials and pigments, state of conservation and painting technique. Raman analysis, Fourier-transform infrared analysis, analysis through energy-dispersive X-ray spectrometry coupled to scanning electron microscopy and pyrolysis coupled to gas chromatography and mass spectrometry were applied. Six analyzed samples showed silicates and kaolin as main components of the ground layers. Also lead white has been found in these layers. Minium, red-earth and mercury sulfide are the red pigments detected in the polychromy. A mixed use of malachite and atacamite has been detected in three green samples. Optical characteristics of atacamite and malachite found in the samples indicate a synthetic origin. The presence of a synthetic organic pigment such as phthalocyanine chlorinated pigment was also revealed. Ultramarine blue pigment, obtained by purification of lapis lazuli, has been detected in the blue sample. As for the binders used, fatty materials and siccative oil were found.     

Evaluation of the effectiveness of treatment products in improving the quality of ceramics used in new and historical buildings

Ceramic samples made with a mixture of 70% ball clay and 30% quartz sand were moulded and then fired at 900 °C in an electric kiln. Samples were then treated with different products and analyses and tests were performed to evaluate the physical changes induced by the application of these products and their effects on the quality of the ceramics. A petrographic study indicated that the ceramics were composed of quartz, small amounts of mullite and sanidine and traces of hematite. Mineral clays (i.e. kaolinite) disappeared during firing. Two consolidating products (Paraloid B72 and Tegovakon V) and one water repellent (Silo 111) were applied to samples by capillarity, and physical changes (colour, water flow, porosity and pore size distribution) were measured. Finally, we carried out salt crystallization tests in order to determine which product improved the quality of the ceramics. Treated samples registered a decrease in porosity and a general increase in pore size. The application of Silo 111 drastically reduced water absorption by immersion and by capillarity. This product was also responsible for a decrease in pore interconnection. Samples treated with Tegovakon V performed better in terms of their overall hydric behaviour. Silo 111 was the only product that did not modify the colour of samples when compared with untreated ones, and after accelerated aging tests, samples treated with this product hindered the absorption of saline solution into ceramic pores and prevented their decay. Paraloid B72 did not improve any of the properties of the ceramics.     

Improving Distance Education for Students with Special Needs: A Qualitative Study of Students’ Experiences with an Online Library Research Course

This article describes a study in which seven students with diverse disabilities participated in a one-credit online library research course which had been adapted to be accessible using the best practices literature on distance education for students with special needs. Students provided feedback on the design of the course and participated in in-depth interviews. Results of this study suggest any given class may have students with different types of disabilities, with different paths toward learning. Using the principles of universal design for learning can improve distance education not only for students with special needs, but for all types of learners.     

Physical activity - an important preanalytical variable

The concentration of several biochemical and hematological biomarkers is strongly influenced by a number of preanalytical variables. Several lines of evidence attest that short, middle, and long-term exercise, as well as the relative intensity of physical effort (from mild to strenuous), may influence a broad array of laboratory variables. The amount of extracellular release and clearance from blood of most of these biomarkers is markedly influenced by the biological characteristics of the molecule(s), level of training, type, intensity and duration of exercise, and time of recovery after training. It is hence noteworthy that test results that fall outside the conventional reference ranges in athletes not only may reflect the presence of a given disease, but may frequently mirror an adaptation to regular training or changes that have occurred during and/or following strenuous exercise, and which should be clearly acknowledged to prevent misinterpretation of laboratory data. The aim of this narrative review is to provide an update about the most significant changes of some biochemical and hematological biomarkers in response to physical exercise, for appropriate interpretation of these changes in the context of physically active subjects.     

Evaluation of sample hemolysis in blood collected by S-Monovette? using vacuum or aspiration mode

Background:

In vitro hemolysis can be induced by several biological and technical sources, and may be worsened by forced aspiration of blood in vacuum tubes. This study was aimed to compare the probability of hemolysis by drawing blood with a commercial evacuated blood collection tube, and S-Monovette used either in the “vacuum” or “aspiration” mode.

Materials and methods:

The study population consisted in 20 healthy volunteers. A sample was drawn into 4.0 mL BD Vacutainer serum tube from a vein of one upper arm. Two other samples were drawn with a second venipuncture from a vein of the opposite arm, into 4.0 mL S-Monovette serum tubes, by both vacuum an aspiration modes. After separation, serum potassium, lactate dehydrogenase (LD) and hemolysis index (HI) were tested on Beckman Coulter DxC.

Results:

In no case the HI exceed the limit of significant hemolysis. As compared with BD Vacutainer, no significant differences were observed for potassium and LD using S-Monovette with vacuum method. Significant increased values of both parameters were however found in serum collected into BD Vacutainer and S-Monovette by vacuum mode, compared to serum drawn by S-Monovette in aspiration mode. The mean potassium bias was 2.2% versus BD Vacutainer and 2.4% versus S-Monovette in vacuum mode, that of LD was 2.7% versus BD Vacutainer and 2.1% versus S-Monovette in vacuum mode. None of these variations exceeded the allowable total error.

Conclusions:

Although no significant macro-hemolysis was observed with any collection system, the less chance of producing micro-hemolysis by S-Monovette in aspiration mode suggest that this device may be used when a difficult venipuncture combined with the vacuum may increase the probability of spurious hemolysis.     

Being “in a Limbo”: Perceptions of Immigration,Identity and Adaptation of Immigrant Students in South Africa and the United States

Much research is available that details student experiences of immigration and adaptation to receiving countries and schools, but few studies analyze the metaphors used by immigrant students (IS) when talking about the immigration experience, or offer a comparative lens through which to view identity negotiation in two very different contexts. The present paper aims to address these gaps by conducting a comparative linguistic analysis of 20 interviews conducted with IS at universities in South Africa and the United States in order to gain a greater understanding of immigration and the types of identity negotiation processes learners undergo in these very different countries. Findings reveal interesting similarities between metaphorical conceptions of immigration across different cultural contexts and a remarkable resilience in the use of adaptation strategies and identity development that leads to salient pedagogical implications for teachers of higher education who face increasingly international classrooms.     

Stretching of DNA confined in nanochannels with charged walls

There is currently a growing interest in control of stretching of DNA inside nanoconfined regions due to the possibility to analyze and manipulate single biomolecules for applications such as DNA mapping and barcoding, which are based on stretching the DNA in a linear fashion. In the present work, we couple Finite Element Methods and Monte Carlo simulations in order to study the conformation of DNA molecules confined in nanofluidic channels with neutral and charged walls. We find that the electrostatic forces become more and more important when lowering the ionic strength of the solution. The influence of the nanochannel cross section geometry is also studied by evaluating the DNA elongation in square, rectangular, and triangular channels. We demonstrate that coupling electrostatically interacting walls with a triangular geometry is an efficient way to stretch DNA molecules at the scale of hundreds of nanometers. The paper reports experimental observations of λ-DNA molecules in poly(dimethylsiloxane) nanochannels filled with solutions of different ionic strength. The results are in good agreement with the theoretical predictions, confirming the crucial role of the electrostatic repulsion of the constraining walls on the molecule stretching.     

Library Study Behaviors in the Age of Ubiquitous Mobile Devices: An Observational Study in Four Academic Libraries

In this study, researchers observed student study behaviors in the libraries of four post-secondary institutions. In all, 2,773 observations were made. This research replicates and expands an earlier study and addresses its limitations. The results of a logistic regression test indicate whether students had a mobile device readily available and where students chose to study in the library best predicted whether they demonstrated a study, as opposed to a non-study, behavior. Specifically, if students were found in quiet study or computer areas, they were more likely to be performing study behaviors. This research has implications for library stakeholders making decisions about the use of library space. Most importantly, this research demonstrates that library spaces are widely used for diverse purposes.     

Comparison of Freelite and N-Latex serum free light chain assays: a critical review

IntroductionThe measurement of serum free light chain (FLC) represents a fundamental aspect on the assessment of patients with monoclonal gammopathies (MG). Different analytical methods for FLC have become available with the possibility to obtain different value with a substantial impact on the assessment of patients with MG. This study aimed to evaluate FLC results obtained with two different assays and how the difference value obtained can impact in the patient’s assessment.Materials and methodsNinety-three patient serum samples that underwent analysis for FLC with two different methods, Serum Freelite (The Binding Site, Birmingham, UK) and N-Latex FLC (Siemens, Marburg, Germany), were included in this retrospective study. Statistical analysis was performed to evaluate correlation, difference, and the grade of concordance between the results obtained with the two methods.ResultsSignificant statistical differences between the results obtained from the two methods were found (P < 0.05). A good correlation was found (0.99 for κ FLC, 0.95 for λ FLC, and 0.94 for the κ/λ ratio, respectively). We found a weighted kappa value of 0.65 for κ/λ ratio, 0.65 for λ FLC and 0.90 for κ FLC. A positive bias found with the Bland-Altman plot mirrors overestimation of κ FLC and κ/λ ratio with Freelite compared to N-Latex, whilst a negative bias underscores underestimation of λ FLC by Freelite compared to N-Latex.ConclusionAlthough in general the concordance between Freelite and N-Latex appears satisfactory, several discrepancies could be evidenced and consequently the two assays are not interchangeable.     

Explorations of a Paradox in Curriculum Control: Resistance to Open-ended Science Inquiry in a School for Self-directed Learning

Despite official government srt (in various jurisdictions around the world) for providing students with opportunities to construct their own knowledge within the context of formal schooling, school science systems continue to place greatest priority on teaching and learning of products of science (e.g., laws and theories), while compromising students’ opportunities to develop realistic conceptions about science and expertise for doing science. Based on qualitative data analyzed using constant comparative methods (based on constructivist grounded theory), we found this also to be the case – paradoxically – in a school belonging to the Canadian Coalition for Self-directed Learning (CCSDL). Schools in this coalition espouse, among various goals, enabling students to construct their own knowledge, in ways and directions suiting their individual needs, interests, perspectives, and abilities, in addition to gaining access to knowledge developed by society. The science department within the coalition school in this study experienced considerable difficulty realizing this goal, despite school-level administrative support for a concerted effort to reinvent itself along these lines. Factors that appeared to influence the science department’s efforts included those in each of Schwab’s (1969) educational "commonplaces;” that is, the curriculum, teachers, students, and the milieu surrounding teaching and learning. Further analysis suggests that results can be explained through reference to a Kuhnian (1962/1996) paradigm conflict – in which the school’s administrative and curricular committee and other members of the CCSDL were unsuccessful in convincing members of the science department (who, in turn, appeared to be supported by the provincial government, parents, and students) to make provisions for more student-directed, openended science inquiry. Assuming that student-led scientific inquiry continues to be an important curricular goal, efforts must continue to be made, therefore, to convince members of the mainstream paradigm that it is a worthy goal.