scholarly journals Student conception and misconception in drawing phosphorus cycle based on worked example learning

2021 ◽  
Vol 1806 (1) ◽  
pp. 012150
Author(s):  
R Faujiyati ◽  
A Rahmat ◽  
Amprasto
2009 ◽  
Vol 23 (2) ◽  
pp. 129-138 ◽  
Author(s):  
Florian Schmidt-Weigand ◽  
Martin Hänze ◽  
Rita Wodzinski

How can worked examples be enhanced to promote complex problem solving? N = 92 students of the 8th grade attended in pairs to a physics problem. Problem solving was supported by (a) a worked example given as a whole, (b) a worked example presented incrementally (i.e. only one solution step at a time), or (c) a worked example presented incrementally and accompanied by strategic prompts. In groups (b) and (c) students self-regulated when to attend to the next solution step. In group (c) each solution step was preceded by a prompt that suggested strategic learning behavior (e.g. note taking, sketching, communicating with the learning partner, etc.). Prompts and solution steps were given on separate sheets. The study revealed that incremental presentation lead to a better learning experience (higher feeling of competence, lower cognitive load) compared to a conventional presentation of the worked example. However, only if additional strategic learning behavior was prompted, students remembered the solution more correctly and reproduced more solution steps.


2014 ◽  
Author(s):  
Charlyn W. Shaw ◽  
Rayne A. Sperling ◽  
David C. Falvo ◽  
Peter T. Olszewski

On the grey forest medium-loamy soil of Vladimir Opolye region we have studied the impact of various methods of basic cultivation and fertilizer systems on the activity of redox and hydrolytic enzymes: ure-ase (nitrogen cycle), invertase (carbon cycle), phosphatase (phosphorus cycle), and catalase, involved in the cycle of carbon in the soil. The second humus horizon with capacity of 19-24cm was found at the depth of 20 - 21 cm on the experimental field. We have studied three modes of basic soil cultivation: an-nual shallow flat plowing (6-8 cm), annual deep flat plowing (20-22 cm), and annual moldboard plowing (20-22 cm) with normal and intensive application of fertilizers. The most enzymatically active layer is 0-20 cm. No relevant difference has been found in the level of enzymes activity between variants of basic soil treatment. Activity of enzymes increases with application of fertilizers on the intensive background. In agrogenic soils, soil enzymatic activity is lower on average by 16-22% compared to the soil of the res-ervoir. The biggest negative transformation of activity has been observed at the urease enzyme (up to 50%). With annual moldboard plowing on the intensive backgroung, enzyme activity has been close to the natural level – 98.4%. Catalise and invertase activity in this case were found to be higher (105 and 116% respectively) than that of natural analogues. Activity of enzymes increases with intensive application of fertilizers as compared with normal background. This is particularly evident with 6-8cm deep beardless plowing and 20-22cm deep moldboard plowing. In general, the obtained biochemical indicators charac-terize the highest environmental sustainability of this variation within our research.


Author(s):  
Breen Creighton ◽  
Catrina Denvir ◽  
Richard Johnstone ◽  
Shae McCrystal ◽  
Alice Orchiston

The purpose of the research upon which this book is based was empirically to investigate whether the ballot requirements in the Fair Work Act do indeed impose a significant obstacle to the taking of industrial action, and whether those provisions are indeed impelled by a legitimate ‘democratic imperative’. The book starts from the proposition that virtually all national legal systems, and international law, recognise the right to strike as a fundamental human right. It acknowledges, however, that in no case is this recognition without qualification. Amongst the most common qualifications is a requirement that to be lawful strike action must first be approved by a ballot of workers concerned. Often, these requirements are said to be necessary to protect the democratic rights of the workers concerned: this is the so-called ‘democratic imperative’. In order to evaluate the true purpose and effect of ballot requirements the book draws upon the detailed empirical study of the operation of the Australian legislative provisions noted above; a comparative analysis of law and practice in a broad range of countries, with special reference to Canada, South Africa, the United Kingdom and the United States; and the jurisprudence of the supervisory bodies of the International Labour Organisation. It finds that in many instances ballot requirements – especially those relating to quorum – are more concerned with curtailing strike activity than with constructively responding to the democratic imperative. Frequently, they also proceed from a distorted perception of what ‘democracy’ could and should entail in an industrial context. Paradoxically, the study also finds that in some contexts ballot requirements can provide additional bargaining leverage for unions. Overall, however, the study confirms our hypothesis that the principal purpose of ballot requirements – especially in Australia and the United Kingdom – is to curtail strike activity rather than to vindicate the democratic imperative, other than on the basis of a highly attenuated reading of that term. We believe that the end-result constitutes an important study of the practical operation of a complex set of legal rules, and one which exposes the dichotomy between the ostensible and real objectives underpinning the adoption of those rules. It also furnishes a worked example of multi-methods empirical, comparative and doctrinal legal research in law, which we hope will inspire similar approaches to other areas of labour law.


2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Wanyi Fu ◽  
Xihui Zhang

AbstractSince the detection of phosphine in the wastewater treatment plants in 1988, more and more investigations revealed that phosphine is closely related to ecological activities on a global scale. Here, we present perspectives on the whole dynamic cycles of phosphorus, particularly in terms of phosphine and its interactions with natural ecosystems, as well as the impacts from human activities. It may conclude that the phosphine-driving cycles of phosphorus depend on the coordination of human activities with natural ecosystems. Most importantly, the extensive recovery of phosphorus in numerous urban wastewater treatment plants may seriously obstruct its global cycles to catch up with the ecological needs in natural ecosystems. Phosphine gas plays an important role in the biogeochemical phosphorus cycle. Phosphorus might be one of the important elements participating in the global climate change together with carbon and nitrogen.


mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. e01966-18 ◽  
Author(s):  
Genis Andrés Castillo Villamizar ◽  
Heiko Nacke ◽  
Marc Boehning ◽  
Kristin Herz ◽  
Rolf Daniel

ABSTRACTPhosphatases, including phytases, play a major role in cell metabolism, phosphorus cycle, biotechnology, and pathogenic processes. Nevertheless, their discovery by functional metagenomics is challenging. Here, soil metagenomic libraries were successfully screened for genes encoding phosphatase activity. In this context, we report the largest number and diversity of phosphatase genes derived from functional metagenome analysis. Two of the detected gene products carry domains which have never been associated with phosphatase activity before. One of these domains, the SNARE-associated domain DedA, harbors a so-far-overlooked motif present in numerous bacterial SNARE-associated proteins. Our analysis revealed a previously unreported phytase activity of the alkaline phosphatase and sulfatase superfamily (cl23718) and of purple acid phosphatases from nonvegetal origin. This suggests that the classical concept comprising four classes of phytases should be modified and indicates high performance of our screening method for retrieving novel types of phosphatases/phytases hidden in metagenomes of complex environments.IMPORTANCEPhosphorus (P) is a key element involved in numerous cellular processes and essential to meet global food demand. Phosphatases play a major role in cell metabolism and contribute to control the release of P from phosphorylated organic compounds, including phytate. Apart from the relationship with pathogenesis and the enormous economic relevance, phosphatases/phytases are also important for reduction of phosphorus pollution. Almost all known functional phosphatases/phytases are derived from cultured individual microorganisms. We demonstrate here for the first time the potential of functional metagenomics to exploit the phosphatase/phytase pools hidden in environmental soil samples. The recovered diversity of phosphatases/phytases comprises new types and proteins exhibiting largely unknown characteristics, demonstrating the potential of the screening method for retrieving novel target enzymes. The insights gained into the unknown diversity of genes involved in the P cycle highlight the power of function-based metagenomic screening strategies to study Earth’s phosphatase pools.


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