Collaborative knowledge building using the Design Principles Database

In this study we describe a mechanism for supporting a community of learning scientists who are exploring educational technologies by helping them to share and collaboratively build design knowledge. The Design Principles Database (DPD) is intended to be built and used by this community to provide an infrastructure for participants to publish, connect, discuss and review design ideas, and to use these ideas to create new designs. The potential of the DPD to serve as a collaborative knowledge-building endeavor is illustrated by analysis of a CSCL study focused on peer-evaluation. The analysis demonstrates how the DPD was used by the researchers of the peer-evaluation study in three phases. In the first phase, design principles were articulated based on a literature review and contributed to the DPD. In the second phase, a peer-evaluation activity was designed based on these principles, and was enacted and revised in a three-iteration study. In the third phase, lessons learned through these iterations were fed back to the DPD. The analysis indicates that such processes can contribute to collaborative development of design knowledge in a community of the learning sciences. Readers of ijCSCL are invited to take part in this endeavor and share their design knowledge with the community.     

Adaptations for Wear Resistance and Damage Resilience: Micromechanics of Spider Cuticular “Tools”

In the absence of minerals as stiffening agents, insects and spiders often use metal‐ion cross‐linking of protein matrices in their fully organic load‐bearing “tools.” In this comparative study, the hierarchical fiber architecture, elemental distribution, and the micromechanical properties of the manganese‐ and calcium‐rich cuticle of the claws of the spider Cupiennius salei, and the Zn‐rich cuticle of the cheliceral fangs of the same animal are analyzed. By correlating experimental results to finite element analysis, functional microstructural and compositional adaptations are inferred leading to remarkable damage resilience and abrasion tolerance, respectively. The results further reveal that the incorporation of both zinc and manganese/calcium correlates well with increased biomaterial's stiffness and hardness. However, the abrasion‐resistance of the claw material cross‐linked by incorporation of Mn/Ca‐ions surpasses that of many other non‐mineralized biological counterparts and is comparable to that of the fang with more than triple Zn content. These biomaterial‐adaptation paradigms for enhanced wear‐resistance may serve as novel design principles for advanced, high‐performance, functional surfaces, and graded materials.     

Control of Polymorph Selection in Amorphous Calcium Carbonate Crystallization by Poly(Aspartic Acid): Two Different Mechanisms

Poly(aspartic acid) (pAsp) is known to stabilize amorphous calcium carbonate (ACC) and affect its crystallization pathways. However, little is known about the mechanisms behind these phenomena. Here it is shown that ACC is stabilized by pAsp molecules in the solution rather than by the amount of pAsp incorporated into the ACC bulk, and that the effect of pAsp on the polymorph selection is entirely different at low and high concentration of pAsp. At low concentrations, pAsp is more effective in inhibiting the nucleation and growth of vaterite than calcite. At high concentrations, when calcite formation is prevented, the crystallization of vaterite proceeds via a pseudomorphic transformation of ACC nanospheres, where vaterite nucleates on the surface of ACC nanospheres and grows by a local transformation of the bulk ACC phase. These results shed some light on the function of pAsp during an ACC‐mediated biomineralization process and provide an explanation for the presence of metastable vaterite at conditions where calcite is thermodynamically favored.     

Development of a sweet pepper harvesting robot

This paper presents the development, testing and validation of SWEEPER, a robot for harvesting sweet pepper fruit in greenhouses. The robotic system includes a six degrees of freedom industrial arm equipped with a specially designed end effector, RGB‐D camera, high‐end computer with graphics processing unit, programmable logic controllers, other electronic equipment, and a small container to store harvested fruit. All is mounted on a cart that autonomously drives on pipe rails and concrete floor in the end‐user environment. The overall operation of the harvesting robot is described along with details of the algorithms for fruit detection and localization, grasp pose estimation, and motion control. The main contributions of this paper are the integrated system design and its validation and extensive field testing in a commercial greenhouse for different varieties and growing conditions. A total of 262 fruits were involved in a 4‐week long testing period. The average cycle time to harvest a fruit was 24 s. Logistics took approximately 50% of this time (7.8 s for discharge of fruit and 4.7 s for platform movements). Laboratory experiments have proven that the cycle time can be reduced to 15 s by running the robot manipulator at a higher speed. The harvest success rates were 61% for the best fit crop conditions and 18% in current crop conditions. This reveals the importance of finding the best fit crop conditions and crop varieties for successful robotic harvesting. The SWEEPER robot is the first sweet pepper harvesting robot to demonstrate this kind of performance in a commercial greenhouse.     

Zeitliche und räumliche Skalen der Fluss-Grundwasser-Interaktion: Ein multidimensionaler hydrogeologischer Untersuchungsansatz

River-groundwater interactions show strong scale-dependencies and are often strongly transient. In this regard, small-scale flow conditions in the hyporheic zone at the interface between surface- and groundwater can be important for process-understanding. This especially includes questions concerning flow conditions in salmonid redds of gravel-bed rivers. The Swiss subalpine river Enziwigger was chosen as an example for a small channelized river with artificial steps within the riverbed. Several methods were developed, tested and combined that capture the four dimensions (three spatial and one temporal) of the interactions between surface water, the hyporheic zone and groundwater, for individual river segments. The setup of a monitoring network as well as the realization of field-measurements provided data for groundwater flow models. Continuous time series of hydraulic data, temperature and electrical conductivity within the river and the riverbed, as well as within the riverine groundwater, allowed identifying zones with significant exchange of surface water and groundwater. Additionally, the data helped describe the transient character of groundwater flow-paths under various hydrological boundary conditions. Results of the field-measurements in combination with transient groundwater flow modeling and scenario analyses illustrate the relevance of dynamically changing infiltration and exfiltration patterns within the riverbed.     

Development and Characterization of Different Black Raspberry Confection Matrices Designed for Delivery of Phytochemicals

Three forms of confections containing black raspberries (BRB) powder were developed to provide controlled release of phytochemicals for oral disease prevention. Our objective was to investigate the impact of varying confection matrices on the release rate of BRB phytochemicals. Confections were developed and prepared. Textural properties of confections were analyzed, compared and correlated with the release rate of phytochemicals from BRB confections with in vitro dissolution test. In the results, BRB content reached 22% in hard candy and pectin‐based confections and 40% in starch‐based confections, respectively. Pectin‐ and starch‐based confections retained >93% of its original anthocyanins after processing while hard candy had 59%. Starch confections showed higher G’ in rheological analysis and higher hardness but lower cohesiveness and springiness in textural profile analysis than pectin confections (P < 0.05). The confection types showed different microstructure with scanning electronic microscopy (SEM). Corresponding to their physicochemical properties, confections showed fast (hard candy), intermediate (pectin confections), and slow (starch confections) release rates with a final releasing time of 90, 150, and 540 min in dissolution studies. Three confections were rated between neither like nor dislike to like slightly (n = 60). Pectin confections had the highest overall acceptance (like slightly) and 62% of subjects rated this type of confection as the most liked ones. These results indicate that delivery matrix could modulate the phytochemical release rate from BRB confection and also influence sensory preference.     

A preliminary investigation into a genetic basis for cis-3-hexen-1-ol odour perception: A genome-wide association approach

Odour perception is controlled by environmental and genetic influences. Most people can discriminate over 10,000 different odours, but the molecular basis of this ability is poorly understood. Little is known about which odorant receptors (ORs) detect what odour compounds, and additional research is required to gain knowledge of why detection thresholds for some odorants vary 1000-fold, or more, across people. The primary purpose of this paper is to describe a research strategy for investigating the genetic basis of human odour perception. Background information on human olfaction, human genetics and the associated research approaches is presented. This is followed by a case study on cis-3-hexen-1-ol, a compound which contributes to the ‘green leaf’ odour (and flavour) in fruit, vegetables and wine. Odour detection threshold data for 48 participants were obtained using the rating R-index methodology. The ability to perceive cis-3-hexen-1-ol odour was tested for association with genetic variability on a genome-wide scale by microarray probe genotyping. A group of significant SNPs on chromosome 6 around the SNP rs9295791 was identified and these localise with a cluster of OR genes which could potentially be involved in perception of cis-3-hexen-1-ol. Further steps required to identify genes and alleles that encode the different ability to perceive cis-3-hexen-1-ol are outlined.     

Spatial and seasonal patterns of fluorescent organic matter in Lake Kinneret (Sea of Galilee) and its catchment basin

Lake Kinneret (Sea of Galilee) is one of the major water resources in Israel. The origin and characteristics of natural organic matter (NOM) in the lake and its tributary rivers were studied using fluorescence excitation emission matrices (EEM) and parallel factor analysis. Two humic-like and one proteinous components were sufficient to describe EEM variability among 167 water samples collected between 2/2005 and 9/2006. The two humic-like components showed different relations in lake and riverine samples. Their vertical distribution in the lake was affected by seasonal stratification and distance from water surface, presumably reflecting the release of humic-like matter from sediments, its production via NOM transformation in the bottom layers, and its photodegradation in the upper layers. Vertical distribution of the proteinous component, indicating biological activity at upper water layers, did not correlate with that of the humic-like components. Dissolved organic carbon concentrations did not show any vertical stratification, emphasizing the power of EEM to explore NOM dynamics.     

Cell-free protein synthesis and assembly on a biochip

Biologically active complexes such as ribosomes and bacteriophages are formed through the self-assembly of proteins and nucleic acids. Recapitulating these biological self-assembly processes in a cell-free environment offers a way to develop synthetic biodevices. To visualize and understand the assembly process, a platform is required that enables simultaneous synthesis, assembly and imaging at the nanoscale. Here, we show that a silicon dioxide grid, used to support samples in transmission electron microscopy, can be modified into a biochip to combine in situ protein synthesis, assembly and imaging. Light is used to pattern the biochip surface with genes that encode specific proteins, and antibody traps that bind and assemble the nascent proteins. Using transmission electron microscopy imaging we show that protein nanotubes synthesized on the biochip surface in the presence of antibody traps efficiently assembled on these traps, but pre-assembled nanotubes were not effectively captured. Moreover, synthesis of green fluorescent protein from its immobilized gene generated a gradient of captured proteins decreasing in concentration away from the gene source. This biochip could be used to create spatial patterns of proteins assembled on surfaces.     

Heat dissipation in wearable computers aided by thermal coupling with the user

Wearable computers and PDA's are physically close to, or are in contact with, the user during most of the day. This proximity would seemingly limit the amount of heat such a device may generate, conflicting with user demands for increasing processor speeds and wireless capabilities. However, this paper explores significantly increasing the heat dissipation capability per unit surface area of a mobile computer by thermally coupling it to the user. In particular, a heat dissipation model of a forearmmounted wearable computer is developed, and the model is verified experimentally. In the process, this paper also provides tools and novel suggestions for heat dissipation that may influence the design of a wearable computer.