Experimental investigations on biopolymer in enhancing the liquid flow in microchannel

Drag reduction has been incorporated in various industrial fields. Most of the works proved that drag reduction is efficient in turbulent flow. It is also observed that polymers can enhance the laminar flow which could be a milestone in medical field. In this work, five straight microchannels with fixed depth of 100, 50, and 60 μm in width and 200, 300, 400, and 500 μm in length were designed and fabricated using direct writing method. Xanthan gum as bio‐based drag reducing additive was chosen and diluted with deionized water to investigate its feasibility in enhancing the laminar flow in the microchannel. Eight different concentrations of xanthan gum ranging from 20 to 500 ppm were used to evaluate the effect of concentration on drag reduction performance using pressure measurement. The maximum flow increment of 34.90% was achieved by utilizing 500 ppm of xanthan gum at an operating pressure of 100 mbar in the microchannel with a width of 500 μm

The Arctic in the twenty-first century: changing biogeochemical linkages across a paraglacial landscape of Greenland

The Kangerlussuaq area of southwest Greenland encompasses diverse ecological, geomorphic, and climate gradients that function over a range of spatial and temporal scales. Ecosystems range from the microbial communities on the ice sheet and moisture-stressed terrestrial vegetation (and their associated herbivores) to freshwater and oligosaline lakes. These ecosystems are linked by a dynamic glacio-fluvial-aeolian geomorphic system that transports water, geological material, organic carbon and nutrients from the glacier surface to adjacent terrestrial and aquatic systems. This paraglacial system is now subject to substantial change because of rapid regional warming since 2000. Here, we describe changes in the eco- and geomorphic systems at a range of timescales and explore rapid future change in the links that integrate these systems. We highlight the importance of cross-system subsidies at the landscape scale and, importantly, how these might change in the near future as the Arctic is expected to continue to warm

Extensive Promoter-Centered Chromatin Interactions Provide a Topological Basis for Transcription Regulation

Higher-order chromosomal organization for transcription regulation is poorly understood in eukaryotes. Using genome-wide Chromatin Interaction Analysis with Paired-End-Tag sequencing (ChIAPET), we mapped long-range chromatin interactions associated with RNA polymerase II in human cells and uncovered widespread promoter-centered intragenic, extragenic, and intergenic interactions. These interactions further aggregated into higher-order clusters, wherein proximal and distal genes were engaged through promoter-promoter interactions. Most genes with promoter-promoter interactions were active and transcribed cooperatively, and some interacting promoters could influence each other implying combinatorial complexity of transcriptional controls. Comparative analyses of different cell lines showed that cell-specific chromatin interactions could provide structural frameworks for cell-specific transcription, and suggested significant enrichment of enhancer-promoter interactions for cell-specific functions. Furthermore, genetically-identified disease-associated noncoding elements were found to be spatially engaged with corresponding genes through long-range interactions. Overall, our study provides insights into transcription regulation by three-dimensional chromatin interactions for both housekeeping and cell-specific genes in human cells

Design, Development and Experiment Analysis of Solar Panel Cleaning System

As the world moves towards a greener future, adoption of renewable energy sources has become very popular and solar power has become one of the most desirable sources of energy. The performance and efficiency of solar panel modules are very much affected by environmental parameters such as temperature, irradiance and dust. Many studies found that the accumulation of dust on the surface of solar panels has seriously reduced the output power of a solar panel. Dust that has accumulated on the panels may reflect or refract the photons thus preventing them from reaching the surface of the panel. Thus, it has reduced the efficiency of solar panels by 3–25%. This study aims to design and fabricate a solar panel cleaning system. The system will be placed atop the solar panels. It consists of an on-board cleaning brush, water tank and control electronics. After the fabrication of the design, testing is done using an acrylic panel embedded with LDR sensors. The intensity of the light passing through the panel is measured before and after multiple cleaning passes. Based on the results, the cleanliness of the surface had significantly improved the efficiency of the panel from 60 to 98% after 3 cleaning passes using water jet

On the Issues of IP Traceback for IPv6 and Mobile IPv6

As the Internet becomes pervasive, the vulnerability of some fundamental design aspects of the Internet has also become significant. Among which, Denial-of-Service (DoS) and Distributed DoS (DDoS) pose significant problems, as they are disruptive to the useful traffics and are hard to prevent. One solution consists in instituting accountability, which hold the attackers accountable for the attack. The key issue is to identify the "real" sources of the attacks as attackers use spoofed IP address to hide their actual network location. However, the Internet architecture does not provide intrinsic support for identifying the real sources of IP packets. Numerous mechanisms have been proposed to "traceback" the real sources. Most of such works have been addressing the IP version 4. In this paper, we address the issues of IP traceback in the context of IPv6 and Mobile IPv6. This paper provides a detailed analysis of these issues and problems. The main problem lies with the transformations that are introduced by IPv6 and Mobile IPv6 protocols, namely tunneling and addresses manipulation. We then propose a solution, including new ICMPv6 messages for traceback co-ordination, to facilitate the traceback mechanism