An experimental study on hydrogen and oxygen evolution was carried out in a sealed zinc-nickel oxide battery. The effects of flowing electrolyte on gas evolution were quantitatively evaluated. The results show that both the hydrogen and oxygen evolution are suppressed by making the electrolyte flow on a regular cycle. This is due to increased cell polarization in the non-flowing case attributed to the concentration boundary layer of zinc (zincate) ion near the anode surfaces. Though the Coulombic efficiency in the flowing case was higher than that in the non-flowing case, the fraction of gas evolution against Coulombic loss was the same for both the cases. When deeply discharging the cell, more hydrogen is evolved in the flowing case than in the non-flowing case. 相似文献
The nonlinear evolution of two fluid interfacial structures such as bubbles and spikes arising due to the combined action of Rayleigh-Taylor and Kelvin-Helmholtz instability is investigated. Using Layzer's model analytic expressions for the asymptotic value of the combined growth rate are obtained in both cases for spikes and bubbles. However, if the overlying fluid is of lower density the interface perturbation behaves in different ways. Depending on the magnitude of the velocity shear associated with Kelvin-Helmholtz instability both the bubble and spike amplitude may simultaneously grow monotonically (instability) or oscillate with time. 相似文献
While much progress has been achieved in the shape‐controlled synthesis of nanocrystals, chemical strategies to define morphology remain primarily empirical. Here, a mechanistic study of the influence of different coordinating ligands on the kinetics and thermodynamics of crystal growth during the preparation of GdOCl by the non‐hydrolytic condensation of GdCl3 and Gd(OiPr)3 is reported. Growth using oleylamine, octadecylamine, trioctylamine, and didodecylamine yields 2D nanosheets with approximately square cross sections, whereas growth in trioctylphosphine oxide yields larger and thicker platelets. The nanostructures are characterized by the presence of spiral growth patterns and dislocations. Apart from preferential binding to specific crystallographic facets, the coordinating ligands are suggested to control the extent of supersaturation, thereby facilitating and tuning dislocation‐mediated growth. Upon depletion of monomers, thermodynamic surface energy considerations become of paramount importance and the nanocrystals are reshaped via mass transport from edges to sides yielding their eventual equilibrium shapes. The mechanisms developed here are thought to be broadly generalizable to the ligand‐directed growth of nanomaterials. 相似文献
Wireless multimedia sensor network (WMSN) is a special wireless sensor network (WSN) made up of several multimedia sensor nodes, specially designed to retrieve multimedia content such as video and audio streams, still images, and scalar sensor data from the environment. Due to strict inherent limitations in terms of processing power, storage and bandwidth, data processing is a challenge in such network. Further, energy is one of the scarcest resources in WSN, especially in WMSN and therefore, saving energy is of utmost importance. Data compression is one of the solutions of such a problem. This paper proposes an energy saving video compression technique for WMSN by judicious combination of partial discrete cosine transform and compressed sensing. This amalgamation exploits the benefits of both the techniques towards fulfilling the objective of saving energy along with achieving desired peak signal to noise ratio (PSNR). When the transform technique ensures low-overhead compression, compressed sensing guarantees the reconstruction of the same video with lesser amount of measurements. Performance of the scheme is measured both qualitatively and quantitatively. In qualitative analysis, overhead of the scheme is measured in terms of storage, computation, and communication overheads and the results are compared with a number of existing schemes including the base scheme. The results show considerable reduction of all such overheads thereby justifying the appropriateness of the proposed scheme for resource-constrained networks like WMSNs. In quantitative analysis, for both ideal and packet loss environment, the scheme is simulated in Cooja, the Contiki network simulator to make it readily implementable in real life mote e.g. MICAz. When compared with the existing state-of-the-art schemes, it performs better not only in terms of 34.31% energy saving but also in getting an acceptable PSNR of 35–37 dB and SSIM of 0.85–0.88 in ideal environment. In packet loss environment, these values are 32.9–35.5 dB and 0.81–0.85 respectively implying acceptable reconstruction even in packet loss environment. Further, it requires the least storage of 51.2 KB. The observation on simulation results is also justified by statistical analysis.
The intestinal epithelium serves as a dynamic barrier to protect the host tissue from exposure to a myriad of inflammatory stimuli in the luminal environment. Intestinal epithelial cells (IECs) encompass differentiated and specialized cell types that are equipped with regulatory genes, which allow for sensing of the luminal environment. Potential inflammatory cues can instruct IECs to undergo a diverse set of phenotypic alterations. Aging is a primary risk factor for a variety of diseases; it is now well-documented that aging itself reduces the barrier function and turnover of the intestinal epithelium, resulting in pathogen translocation and immune priming with increased systemic inflammation. In this study, we aimed to provide an effective epigenetic and regulatory outlook that examines age-associated alterations in the intestines through the profiling of microRNAs (miRNAs) on isolated mouse IECs. Our microarray analysis revealed that with aging, there is dysregulation of distinct clusters of miRNAs that was present to a greater degree in small IECs (22 miRNAs) compared to large IECs (three miRNAs). Further, miRNA–mRNA interaction network and pathway analyses indicated that aging differentially regulates key pathways between small IECs (e.g., toll-like receptor-related cascades) and large IECs (e.g., cell cycle, Notch signaling and small ubiquitin-related modifier pathway). Taken together, current findings suggest novel gene regulation pathways by epithelial miRNAs in aging within the gastrointestinal tissues. 相似文献
ABSTRACTThe residing microbiome with its vast repertoire of genes provide distinctive properties to the host by which they can degrade and utilise nutrients that otherwise pass the gastro-intestinal tract unchanged. The polyphenols in our diet have selective growth promoting effects which is of utmost importance as the state of good health has been linked to dominance of particular microbial genera. The polyphenols in native form might more skilfully exert anti-oxidative and anti-inflammatory properties but in a living system it is the microbial derivatives of polyphenol that play a key role in determining health outcome. This two way interaction has invoked great interest among researchers who have commenced several clinical surveys and numerous studies in in-vitro, simulated environment and living systems to find out in detail about the biomolecules involved in such interaction along with their subsequent physiological benefits. In this review, we have thoroughly discussed these studies to develop a fair idea on how the amalgamation of probiotics and polyphenol has an immense potential as an adjuvant therapeutic for disease prevention as well as treatment. 相似文献
We present a new analytical direct parameter-extraction methodology for obtaining the small-signal equivalent circuit of HBTs. It is applied to cryogenically operated SiGe HBTs as a means to allow circuit design of SiGe HBT low-noise amplifiers for cooled radio astronomy applications. We split the transistor into an intrinsic transistor (IT) piece modeled as a Pi-topology, and the quasi-intrinsic transistor (QIT), obtained from the IT after that the base resistance (Rb) has been removed. The relations between Z-Y-parameters of the IT and QIT are then established, allowing us to propose a new methodology for determining Rb. The present extraction method differs from previous studies in that each of the model elements are obtained from exact equations that do not require any approximations, numerical optimization, or post-processing. The validity of this new extraction methodology is demonstrated by applying it to third-generation SiGe HBTs operating at liquid-nitrogen temperature (77 K) across the frequency range of 2-22 GHz. 相似文献
Surveillance videos of public places often consist of group activities composed from multiple co-occurring individual activities.
However, latent topic models, such as Latent Dirichlet Allocation (LDA), which have been successfully used to discover individual
activities, do not discover group activities. In this paper we propose a method to discover group activities along with individual
activities. We use a two layer latent structure where a latent variable is used to discover correlation of individual activities
as a group activity using multinomial distribution. Each individual activity is in turn represented as a distribution over
local visual features. We use a Gibbs sampling-based algorithm to jointly infer the individual and group activities. Our method
can summarize not only the individual activities but also the common group activities in a video. We demonstrate the strength
of our method by discovering activities and the salient correlation amongst them in real life videos of crowded public places. 相似文献