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1.
Elsholtzia splendens (Lamiaceae) is a copper-tolerant plant species growing on copper deposits in the south of China. Chromatographic separation of n-BuOH extracts from the flowering aerial biomass afforded apigenin-7-O-β-d-glycoside, using macroporous resin, Sephadex? LH-20 gel, polyamide resin as well as preparative high-performance liquid chromatography (P-HPLC) columns. Chemical structure was elucidated using HPLC/ESI-MS (electrospray ionization-mass spectrometry), Fourier transform infrared (FTIR), and 1D- and 2D-nuclear magnetic resonance (NMR). Apigenin-7-O-β-d-glycoside could be the post-harvesting product from E. splendens biomass.  相似文献   

2.
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3.
This study examined the effects of a 10 week invented writing program with five-year-old preschoolers (mean age 5.7 years) on their immediate post intervention literacy skills and also the facilitative effects of the intervention on the subsequent learning to read during the first 6 months of schooling. The study included 105 children (54 girls) from 12 preschools in Norway. The preschools were randomly assigned to the experimental group with the invented writing program, or the control group with the ordinary program offered to preschoolers. The classroom-based programs (40 sessions) were conducted by the children’s regular teachers. The children’s emergent literacy skills were evaluated using a pre-test, a post-test and a follow-up test 6 months later, and the data were analyzed using latent autoregressive models. The results showed that the invented writing group performed significantly better than the control group on the post-test for the measures of phoneme awareness (d = .54), spelling (d = .65) and word reading (d = .36). Additionally, indirect effects were observed on the delayed follow-up tests on phoneme awareness (d = .45), spelling (d = .48) and word reading (d = .26). In conclusion, we argue that invented writing appeared to smooth the progress of emergent literacy skills in preschool, including the subsequent reading development in school. Contextualized in a semi-consistent orthography and a preschool tradition that does not encourage the learning of written language skills, the findings add to our knowledge of how children learn to write and read.  相似文献   

4.
Microbial attacks during storage are one of the primary causes of product deterioration, and can limit the process of prolonging the shelf-life of harvested food. In this study, sweet potatoes were stored at temperatures of 13, 21, and 29 °C for 4 weeks. Samples were collected during storage and plated on potato dextrose agar, from which axenic mold cultures were obtained and identified using 26S rRNA gene sequences. Physiological changes of potato tubers were assessed with respect to pathogenicity, enzyme activity, and atmospheric storage conditions. Six fungal species were identified, namely Penicillium chrysogenum (P. rubens), P. brevicompactum, Mucor circinelloides, Cladosporium cladosporiodes, P. expansum, and P. crustosum. The following fungal isolates, namely P. expansum, P. brevicompactum, and Rhizopus oryzae, were recovered from the re-infected samples and selected according to their levels of enzyme activity. This study revealed high levels of activity for cellulase and pectinase, which were most notable during the initial three days of testing, and were followed by a steady decrease (P<0.05). Polygalacturonase activity was prominent with values ranging from 12.64 to 56.79 U/mg (P. expansum) and 18.36 to 79.01 U/mg (P. brevicompactum). Spoilage was obvious in the control group, which had a 100% decay at the end of the experimental period compared with samples treated with iprodione and sodium hypochlorite, in which the decay rates were 5% and 55%, respectively. The data for the iprodione- and sodium hypochlorite-treated samples at the end of the 3-month storage period showed that they were significantly different (P=0.041), with the sodium hypochlorite-treated samples producing twice the rate of infection compared to the iprodione-treated samples. The comparative rate of the progression of decay in the treated samples can be expressed as iprodione<sodium hypochlorite<control. This study demonstrates that sweet potato tissue damage is due to the activities of microbial enzymes and, in particular, the pectinases of the organisms isolated from the infected potato tissues, and suggests the advantages of utilizing iprodione as a curing agent for potato tubers before storage.  相似文献   

5.
A comprehensive, statistical review of gender differences in verbal performance has not been conducted in several decades and the majority of previous work on this topic used published studies that often include small, non-representative samples. The introduction of national legislation in US public schools required schools to assess and publicly report verbal performance, thus providing verbal assessment data for millions of American students. The current study presents a meta-analysis of gender differences in US state verbal assessments. Data were collected from the departments of education in 16 states representing more than 10 million US students in grades 3 through 11. Results indicated a small gender difference favoring females for overall verbal performance (d?=?0.29). However, when type of assessment was considered, the female advantages in reading (d?=?0.19) and language arts (d?=?0.29) were smaller than in writing performance (d?=?0.45). The small gender differences in verbal performance increased in a linear pattern from grades 3 to 8 and then remained steady in high school.  相似文献   

6.
Research has demonstrated that in controlled experiments in which small groups are being tutored by researchers, reading-strategy instruction is highly effective in fostering reading comprehension (Palincsar & Brown, Cognition and Instruction, 1(2), 117–175, 1984). It is unclear, however, whether reading-strategy interventions are equally effective in whole-classroom situations in which the teacher is the sole instructor for the whole class. This meta-analysis focuses on the effects of reading-strategy interventions in whole-classroom settings. Results of studies on the effectiveness of reading-strategy interventions in whole-classroom settings were summarized (Nstudies?=?52, K?=?125) to determine the overall effects on reading comprehension and strategic ability. In addition, moderator effects of intervention, study, and student characteristics were explored. The analysis demonstrated a very small effect on reading comprehension (Cohen’s d?=?.186) for standardized tests and a small effect (Cohen’s d?=?.431) on researcher-developed reading comprehension tests. A medium overall effect was found for strategic ability (Cohen’s d?=?.786). Intervention effects tended to be lower for studies that did not control for the hierarchical structure of the data (i.e. multilevel analyses).For interventions in which “setting reading goals” was part of the reading-strategy package, effects tended to be larger. In addition, effects were larger for interventions in which the trainer was the researcher as opposed to teachers and effect sizes tended to be larger for studies conducted in grades 6–8. Implications of these findings for future research and educational practice are discussed.  相似文献   

7.
A membrane bioreactor (MBR) was established for treating harbor oily wastewater. It showed good removal performance for chemical oxygen demand (COD), oil content, suspended solids (SS), and other pollutants. However, serious membrane fouling occurred. It was recognized that the extracellular polymeric substances (EPS) accumulated on the membrane surface, especially the proteins, were of great importance for the transmembrane pressure (TMP) increment and membrane fouling. The MBR was optimized via improving aeration rate and reducing the ratio of Ar/Ad (Ar and Ad are the cross-sectional areas of the riser and the downcomer of the MBR). The increasing rate of TMP was slowed, indicating that the optimization strategy could effectively mitigate membrane fouling. Microbial community evolution was monitored and analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), cloning, and sequencing of 16S ribosomal ribonucleic acid (rRNA) fragments. Results revealed that low community shift occurred during the whole operational period. Geobacter sp. and Rhodocyclales sp., which have also been identified by other studies in a petroleum refinery wastewater MBR or an infiltration basin receiving highway runoff, dominated in the MBR system throughout. Comamonas sp. was thought to accommodate the lower aeration rate in this study, while Rhodocyclales sp. preferred the higher aeration rate. In addition, during the operational time under high organic loading rate, a few species were present in abundance, and may have been responsible for the good removal performance at this time.  相似文献   

8.
Chlamydia psittaci is an important zoonotic pathogen in birds and may be transmitted to humans and result in severe respiratory disease. To assess the prevalence and genotype of C. psittaci in birds in Kunming, Yunnan, China, a total of 136 specimens of psittacine birds involving 8 species were collected from the city’s zoos (n=60) and pet markets (n=76). The frequency of C. psittaci infection was 19.9% (27/136) in the psittacine birds. The prevalence of C. psittaci was higher in pet birds (26.3%; 20/76) than in zoo birds (11.7%; 7/60) (P=0.034). In particular, among Agapornis fischeri, the C. psittaci infection (50%; 10/20) was significantly more frequent in the pet markets than in the zoos (P=0.006). In addition, the highest prevalence of 41.2% (7/17) was found in Ara ararauna. To determine the genotype of C. psittaci, 23 OmpA gene fragments (about 1.4 kb) in 27 positive samples were successfully amplified and sequenced. Phylogenetic analysis showed that all the 23 strains belonged to genotype A. Our results demonstrate the high prevalence of C. psittaci genotype A infection in psittacine birds in Yunnan Province, suggesting a potential threat to human health in this area. Therefore, it is necessary to take effective measures to prevent the spread of C. psittaci among psittacine birds, as well as among employees and customers.  相似文献   

9.
An extracellular β-glucosidase produced by Aspergillus terreus was identified, purified, characterized and was tested for the hydrolysis of soybean isoflavone. Matrix-assisted laser desorption/ionization with tandem time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF MS) revealed the protein to be a member of the glycosyl hydrolase family 3 with an apparent molecular mass of about 120 kDa. The purified β-glucosidase showed optimal activity at pH 5.0 and 65 °C and was very stable at 50 °C. Moreover, the enzyme exhibited good stability over pH 3.0–8.0 and possessed high tolerance towards pepsin and trypsin. The kinetic parameters Km (apparent Michaelis-Menten constant) and Vmax (maximal reaction velocity) for p-nitrophenyl-β-d-glucopyranoside (pNPG) were 1.73 mmol/L and 42.37 U/mg, respectively. The Km and Vmax for cellobiose were 4.11 mmol/L and 5.7 U/mg, respectively. The enzyme efficiently converted isoflavone glycosides to aglycones, with a hydrolysis rate of 95.8% for daidzin, 86.7% for genistin, and 72.1% for glycitin. Meanwhile, the productivities were 1.14 mmol/(L·h) for daidzein, 0.72 mmol/(L·h) for genistein, and 0.19 mmol/(L·h) for glycitein. This is the first report on the application of A. terreus β-glucosidase for converting isoflavone glycosides to their aglycones in soybean products.  相似文献   

10.
This longitudinal study examined the role of metaconceptual awareness in the change and the durability of preservice teachers’ conceptual understandings over the course of several months. Sixteen preservice early childhood teachers participated in the study. Semi-structured interviews were conducted to reveal the participants’ conceptual understandings of lunar phases (pre, post, and delayed-post) and level of metaconceptual awareness (delayed-post only). Based on the change and stability in participants’ conceptual understandings from pre to post and from post to delayed-post interviews, participants’ conceptual understandings were assigned into three groups that described the profile of their long-term conceptual understandings: “decay or stability”, “continuous growth”, and “growth and stability”. The results indicated that participants in the “continuous growth” and “growth and stability” groups had significantly higher metaconceptual awareness scores than participants in the “decay or stability” group. The results provided evidence that metaconceptual awareness plays a more decisive role in the restructuring of conceptual understandings than the durability of conceptual understandings.  相似文献   

11.
To report a rare case of fungal spondylodiscitis in a patient recovered from H7N9 virus infection and perform a literature review of the different characteristics of Candida and Aspergillus spondylodiscitis, we reviewed cases of spondylodiscitis caused by Candida and Aspergillus species. Data, including patients’ information, pathogenic species, treatment strategy, outcomes, and relapses, were collected and summarized. The characteristics of Candida and Aspergillus spondylodiscitis were compared to see if any differences in clinical features, management, or consequences could be detected. The subject of the case study was first misdiagnosed as having a vertebral tumor, and then, following open biopsy, was diagnosed as having fungal spondylodiscitis. The patient made a good recovery following radical debridement. Seventy-seven additional cases of Candida spondylodiscitis and 94 cases of Aspergillus spondylodiscitis were identified in the literature. Patients with Candida spondylodiscitis tended to have a better outcome than patients with Aspergillus spondylodiscitis (cure rate 92.3% vs. 70.2%). Candida was found more frequently (47.8%) than Aspergillus (26.7%) in blood cultures, while neurological deficits were observed more often in patients with Aspergillus spondylodiscitis (43.6% vs. 25.6%). Candida spinal infections were more often treated by radical debridement (60.5% vs. 39.6%). Patients with Candida spondylodiscitis have better outcomes, which may be associated with prompt recognition, radical surgical debridement, and azoles therapy. A good outcome can be expected in fungal spondylodiscitis with appropriate operations and anti-fungal drugs.  相似文献   

12.
A great amount of foodborne pathogens were Gram-positive(G+) bacteria, a threat to public health. In this study, considering the binding ability of nisin towards G+ bacteria and the stable fluorescent ability of EGFP protein, a fluorescent nisin–EGFP protein probe was constructed by a gene engineering method. Nisin and EGFP were used as the receptor and fluorophore, respectively, to detect G+ bacteria. The nisin and egfp gene were amplified separately according to the sequence published in Gen Bank using unique primers. The two genes were cloned into a pET-28b(+) vector resulting in apET-28b(+)–nisin–egfp vector. The vector was transferred into Escherichia coli(E. coli) BL21(DE3) for expression. The expressed protein was extracted, purified by a Ni–NTA column, and then tested by the SDS-PAGE method to confirm its molecular weight. Listeria monocytogenes(L.monocytogenes), Staphylococcus aureus(S. aureus), and Micrococcus luteus(M. luteus) were used as the representations of G+ bacteria. E. coli O157, representing the gram-negative(G-) bacteria, was used as a negative control. The binding specificity of the recombinant protein was performed on two types of bacteria and then detected through fluorescent microscopy. The results indicated that the nisin–EGFP probe could detect G+ bacteria at 10~8CFU/mL.  相似文献   

13.
This meta-analysis synthesizes the last two decades of experimental and quasi-experimental research on reading instruction across academic contexts (e.g., social studies, science, mathematics, English language arts) for English learners (ELs) in grades 4 through 8, to determine (a) the overall effectiveness of reading instruction for upper elementary and middle school students who are ELs and (b) how the magnitude of the effect varies based on student, instructional, and study characteristics. The analysis included a total of 11 studies with 46 individual effect sizes and yielded a mean effect size of g?=?0.35 across all (i.e., standardized and unstandardized) reading measures, g?=?0.01 across standardized reading measures, and g?=?0.43 across unstandardized reading measures. For all reading, unstandardized reading, all vocabulary, and unstandardized vocabulary measures, results suggest that higher quality studies tended to have smaller effects, and these effects were even more evident for unstandardized measures (i.e., one unit increase in study quality was associated with decreased effects: g?=?0.21, g?=?0.30, g?=?0.24, g?=?0.30, respectively). For all comprehension measures, effects were larger for instruction that included both vocabulary and comprehension (g?=?0.39) than for instruction that focused on vocabulary alone (g?=?0.08). Results suggest the benefit of developing and refining high-impact approaches to reading instruction for ELs that can be delivered across content areas and grades.  相似文献   

14.
As an easy application of the intermediate value theorem, one can show that for any continuous function f: [0, 1] → ? with f (0) = f (1), there are points a, a + 1/2 both in [0, 1] such that f (a) = f (a + 1/2). In this note, we show that this property holds with 1/2 replaced by any number of the form 1/n for a positive integer n. More interestingly, we show that this is false for every number not of the form 1/n.  相似文献   

15.
1　Introduction　AmatrixA∈Cn×missaidtobecentrohermitianifA =Jn AJm,andskewcentrohermitianifA =-Jn AJm,where Adenotetheconjugateofthema trixAandJlisthepermutationmatrixoforderlwithonesonthecrossdiagonal(bottomlefttotopright)andzeroselsewhere .ThehermitianToeplitzmatricesformanimportantsubclassofcentrohermi tianmatriceswhichoccurnaturallyindigitalsignalprocessingandotherareas ,seeforinstance[1] andreferencetherein .Thecentrohermitianandrelatedmatricesrecentlyplayanimportantroleinthesolu…  相似文献   

16.
The objective of this study was to describe the fecal microbiota succession of piglets from birth to post-weaning by pyrosequencing. The dominant bacterial phyla were Bacteroidetes, Firmicutes, Proteobacteria, and Fusobacteria, although the composition of the fecal microbiota changed as the piglets grew. Bacteroides, Parabacteroides, Prevotella, Lactobacillus, unclassified Lachnospiraceae, Ruminococcus, Oscillospira, Phascolarctobacterium, and Desulfovibrio were the core genera in the feces of piglets and existed from birth to post-weaning. Bacteroides was the most abundant at birth; however, the proportion of Bacteroides decreased as the piglets aged, while the proportion of Prevotella increased until it became the most abundant genus at the post-weaning stage. Principal coordinate analysis indicated that the microbial communities of piglet fecal samples from birth to post-weaning could be separated into four groups according to the similarity of community composition. These corresponded to time points on day 0 (birth); day 7; days 14, 21, and 28 (pre-weaning); and day 35 (post-weaning). This study suggests that the development of the intestinal microbiota in the piglet is a gradual and sequential process. This methodology establishes a basis for broader studies to investigate the microbiota of the piglet intestinal tract.  相似文献   

17.

Objective

The aim of this study was to compare complications and oncologic outcomes of patients undergoing laparoscopic distal pancreatectomy (LDP) and open distal pancreatectomy (LDP) at a single center.

Methods

Distal pancreatectomies performed for pancreatic ductal adenocarcinoma during a 4-year period were included in this study. A retrospective analysis of a database of this cohort was conducted.

Results

Twenty-two patients underwent LDP for pancreatic ductal adenocarcinoma, in comparison to seventy-six patients with comparable tumor characteristics treated by LDP. No patients with locally advanced lesions were included in this study. Comparing LDP group to LDP group, there were no significant differences in operation time (P=0.06) or blood loss (P=0.24). Complications (pancreatic fistula, P=0.62; intra-abdominal abscess, P=0.44; postpancreatectomy hemorrhage, P=0.34) were similar. There were no significant differences in the number of lymph nodes harvested (11.2±4.6 in LDP group vs. 14.4±5.5 in LDP group, P=0.44) nor the rate of patients with positive lymph nodes (36% in LDP group vs. 41% in LDP group, P=0.71). Incidence of positive margins was similar (9% in LDP group vs. 13% in LDP group, P=0.61). The mean overall survival time was (29.6±3.7) months for the LDP group and (27.6±2.1) months for LDP group. There was no difference in overall survival between the two groups (P=0.34).

Conclusions

LDP is a safe and effective treatment for selected patients with pancreatic ductal adenocarcinoma. A slow-compression of pancreas tissue with the GIA stapler is effective in preventing postoperative pancreatic fistula. The oncologic outcome is comparable with the conventional open approach. Laparoscopic radical antegrade modular pancreatosplenectomy contributed to oncological clearance.
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18.
Wind speed and direction data during typhoon Meari were obtained from eight anemometers installed at heights of 10, 20, 30, and 40 m on a 40-m tower built in the Pudong area of Shanghai. Wind-turbulence characteristics, including wind-speed profile, turbulence integral scale, power spectra, correlations, and coherences were analyzed. Wind-speed profiles varied with time during the passage of Meari. Measured wind-speed profiles could be expressed well by both a power law and a log law. Turbulence integral scales for u, v, and w components all increased with wind speed. The ratios of the turbulence scales among the turbulence components averaged for all 10-min data were 1? 0.69?0.08 at 10 m, 1?0.61?0.09 at 20 m, and 1?0.65?0.13 at 40 m. The turbulence integral scales for the u and v components increased with average gust time, but the turbulence integral scale for the w component remained almost constant when the gust duration was greater than 10 min. The decay factor of the coherence function increased slightly with wind speed, with average values for longitudinal and lateral dimensions of 14.3 and 11.3, respectively. The slope rates of the turbulence spectra in the inertial range were less than ?5/3 at first, but gradually satisfied the Kolmogorov 5/3 law. The longitudinal wind-power fluctuation spectrum roughly fitted the von Karman spectrum, but slight deviations occurred in the high-frequency band for lateral and vertical wind-power fluctuation spectra.  相似文献   

19.
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20.
Recent research in a text-based educational context has demonstrated a seemingly paradoxical disfluency effect in reading, namely that learning with hard-to-read (disfluent) materials helps learners recall more details than learning with easy-to-read (fluent) materials. Many follow-up studies using a variety of participants, learning materials, and experimental designs have been conducted to verify the effects of disfluency manipulation on recall, transfer, judgments of learning, and learning time. However, a number of them have failed to replicate this effect and the mixed findings bring into question the generality of the disfluency effect with respect to learning. In this meta-analysis, we tested the overall effect of perceptual disfluency on learning with texts, as well as moderators of this effect, based on 25 empirical articles involving 3135 participants. Results showed that overall, there was no effect of perceptual disfluency on recall (d?=???0.01) or transfer (d?=?0.03), but perceptual disfluency did reduce participants’ judgments of learning (d?=???0.43) and increase learning time (d?=?0.52). Tests of moderation focused on the most commonly studied dependent measure, namely recall. There was no evidence that characteristics of the participants, learning material, or experimental design moderated the effect of perceptual disfluency on recall. In general, though perceptual disfluency can be used as an effective metacognitive cue to reduce judgments of learning and increase learning time, there is not enough evidence to show that it either stimulates analytic processing or increases extraneous cognitive load.  相似文献   

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