56 research outputs found
Inducing Stratification of Colloidal Mixtures with a Mixed Binary Solvent
Molecular dynamics simulations are used to demonstrate that a binary solvent
can be used to stratify colloidal mixtures when the suspension is rapidly
dried. The solvent consists of two components, one more volatile than the
other. When evaporated at high rates, the more volatile component becomes
depleted near the evaporation front and develops a negative concentration
gradient from the bulk of the mixture to the liquid-vapor interface while the
less volatile solvent is enriched in the same region and exhibit a positive
concentration gradient. Such gradients can be used to drive a binary mixture of
colloidal particles to stratify if one is preferentially attracted to the more
volatile solvent and the other to the less volatile solvent. During solvent
evaporation, the fraction of colloidal particles preferentially attracted to
the less volatile solvent is enhanced at the evaporation front, whereas the
colloidal particles having stronger attractions with the more volatile solvent
are driven away from the interfacial region. As a result, the colloidal
particles show a stratified distribution after drying, even if the two colloids
have the same size.Comment: 11 pages, 6 figures, 1 page Supporting Information with 2 figure
Measuring the difficulty of text translation: The combination of text-focused and translator-oriented approaches
This paper explores the impact of text complexity on translatorsâ subjective perception of translation difficulty and on their cognitive load. Twenty-six MA translation students from a UK university were asked to translate three English texts with different complexity into Chinese. Their eye movements were recorded by an eye-tracker, and their cognitive load was self-assessed with a Likert scale before translation and NASA-TLX scales after translation. The results show that: (i) the intrinsic complexity measured by readability, word frequency and non-literalness was in line with the results received from informantsâ subjective assessment of translation difficulty; (ii) moderate and positive correlations existed between most items in the self-assessments and the indicator (fixation and saccade durations) obtained by the eye-tracking measurements; and (iii) the informantsâ cognitive load as indicated by fixation and saccade durations (but not for pupil size) increased significantly in two of the three texts along with the increase in source text complexity
Neglected Effects of Inoculum Preservation on the Start-Up of Psychrophilic Bioelectrochemical Systems and Shaping Bacterial Communities at Low Temperature
Bioelectrochemical systems (BESs) are capable of simultaneous wastewater treatment and resource recovery at low temperatures. However, the direct enrichment of psychrophilic and electroactive biofilms in BESs at 4°C is difficult due to the lack of understanding in the physioecology of psychrophilic exoelectrogens. Here, we report the start-up and operation of microbial fuel cells (MFCs) at 4°C with pre-acclimated inocula at different temperatures (4°C, 10°C, 25°C, and â20°C) for 7 days and 14 days. MFCs with 7-day-pretreated inocula reached higher peak voltages than did those with 14-day-pretreated inocula. The highest power densities were obtained by MFCs with 25°C â 7-day-, 25°C â 14-day-, and 4°C â 7-day-pretreated inocula (650â700 mW/m2). In contrast, the control MFCs with untreated inocula were stable at 450 mW/m2. The power densities of MFCs with 7-day-pretreated inocula were higher than those obtained by MFCs with 14-day-pretreated inocula. The MFCs with 10°C â 7-day-pretreated inocula and the control MFCs showed higher chemical oxygen demand (COD) removal (90â91%) than other MFCs. Illumina HiSeq sequencing based on 16S rRNA gene amplicons indicated that bacterial communities of the anode biofilms were shaped by pretreated inocula at different temperatures. Compared with the control MFCs with untreated inocula, MFCs with temperature-pretreated inocula demonstrated higher microbial diversity, but did not do so with â20°C-pretreated inocula. Principal components analysis (PCA) revealed an obvious separation between the inocula pretreated at 4°C and those pretreated at 10°C, implying that bacterial community structures could be shaped by pretreated inocula at low temperatures. The pretreatment period also had a diverse impact on the abundance of exoelectrogens and non-exoelectrogens in MFCs with inocula pretreated at different temperatures. The majority of the predominant population was affiliated with Geobacter with a relative abundance of 17â70% at different pre-acclimated temperatures, suggesting that the exoelectrogenic Geobacter could be effectively enriched at 4°C even with inocula pretreated at different temperatures. This study provides a strategy that was previously neglected for fast enrichment of psychrophilic exoelectrogens in BESs at low temperatures
Research progress of hydrogels as delivery systems and scaffolds in the treatment of secondary spinal cord injury
Secondary spinal cord injury (SSCI) is the second stage of spinal cord injury (SCI) and involves vasculature derangement, immune response, inflammatory response, and glial scar formation. Bioactive additives, such as drugs and cells, have been widely used to inhibit the progression of secondary spinal cord injury. However, the delivery and long-term retention of these additives remain a problem to be solved. In recent years, hydrogels have attracted much attention as a popular delivery system for loading cells and drugs for secondary spinal cord injury therapy. After implantation into the site of spinal cord injury, hydrogels can deliver bioactive additives in situ and induce the unidirectional growth of nerve cells as scaffolds. In addition, physical and chemical methods can endow hydrogels with new functions. In this review, we summarize the current state of various hydrogel delivery systems for secondary spinal cord injury treatment. Moreover, functional modifications of these hydrogels for better therapeutic effects are also discussed to provide a comprehensive insight into the application of hydrogels in the treatment of secondary spinal cord injury
Diversity of NC10 bacteria associated with sediments of submerged Potamogeton crispus (Alismatales: Potmogetonaceae)
Background The nitrite-dependent anaerobic methane oxidation (N-DAMO) pathway, which plays an important role in carbon and nitrogen cycling in aquatic ecosystems, is mediated by âCandidatus Methylomirabilis oxyferaâ (M. oxyfera) of the NC10 phylum. M. oxyfera-like bacteria are widespread in nature, however, the presence, spatial heterogeneity and genetic diversity of M. oxyfera in the rhizosphere of aquatic plants has not been widely reported. Method In order to simulate the rhizosphere microenvironment of submerged plants, Potamogeton crispus was cultivated using the rhizobox approach. Sediments from three compartments of the rhizobox: root (R), near-rhizosphere (including five sub-compartments of one mm width, N1âN5) and non-rhizosphere (>5 mm, Non), were sampled. The 16S rRNA gene library was used to investigate the diversity of M. oxyfera-like bacteria in these sediments. Results Methylomirabilis oxyfera-like bacteria were found in all three sections, with all 16S rRNA gene sequences belonging to 16 operational taxonomic units (OTUs). A maximum of six OTUs was found in the N1 sub-compartment of the near-rhizosphere compartment and a minimum of four in the root compartment (R) and N5 near-rhizosphere sub-compartment. Indices of bacterial community diversity (Shannon) and richness (Chao1) were 0.73â1.16 and 4â9, respectively. Phylogenetic analysis showed that OTU1-11 were classified into group b, while OTU12 was in a new cluster of NC10. Discussion Our results confirmed the existence of M. oxyfera-like bacteria in the rhizosphere microenvironment of the submerged plant P. crispus. Group b of M. oxyfera-like bacteria was the dominant group in this study as opposed to previous findings that both group a and b coexist in most other environments. Our results indicate that understanding the ecophysiology of M. oxyfera-like bacteria group b may help to explain their existence in the rhizosphere sediment of aquatic plant
Comparability of difficulty levels of translation tasks in CET-6 parallel test forms: evidence from product and process-based data
This study investigates the comparability of three parallel translation tasks selected from a College English Test Band-6 (CET-6) and explores the major linguistic features contributing to translation difficulty. Data obtained from the participantsâ subjective rating, eye-tracking, and performance evaluation were triangulated to measure the comparability of difficulty levels of parallel translation tasks. Data of word translation entropy, translation errors, and participantsâ retrospective reports were correlated to examine the difficulty triggers. The results show that: (i) the text comparability was evidenced by eye-tracking indicators and performance measurements, but not supported by subjective ratings; (ii) the domain content words (DCWs) were reported by the participants as the major cause of translation difficulties and the unequal number of DCWs among the three tasks led to inconsistent ratings for the task difficulty. Our findings suggest that test-takersâ subjective perception and their cognitive skills deserve serious consideration by test designers, as these two factors can better demonstrate difficulty levels among parallel tasks. Our study postulates a new direction to establish a relationship between task characteristics and test validity, and provides suggestions for the CET-6 committee and other examination boards with practical methods to be able to compare the difficulty levels of parallel translation tasks
A Fast Image Stitching Algorithm via Multiple-Constraint Corner Matching
Video panoramic image stitching is in general challenging because there is small overlapping between original images, and stitching processes are therefore extremely time consuming. We present a new algorithm in this paper. Our contribution can be summarized as a multiple-constraint corner matching process and the resultant faster image stitching. The traditional Random Sample Consensus (RANSAC) algorithm is inefficient, especially when stitching a large number of images and when these images have quite similar features. We first filter out many inappropriate corners according to their position information. An initial set of candidate matching-corner pairs is then generated based on grayscales of adjacent regions around each corner. Finally we apply multiple constraints, e.g., their midpoints, distances, and slopes, on every two candidate pairs to remove incorrectly matched pairs. Consequently, we are able to significantly reduce the number of iterations needed in RANSAC algorithm so that the panorama stitching can be performed in a much more efficient manner. Experimental results demonstrate that (i) our corner matching is three times faster than normalized cross-correlation function (NCC) rough match in traditional RANSAC algorithm and (ii) panoramas generated from our algorithm feature a smooth transition in overlapping image areas and satisfy human visual requirements
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