首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 562 毫秒
1.
In this study, the in vitro degradation of yarns made from PCL electrospun fibers containing various concentrations of ampicillin sodium salt was investigated. PCL fibers were electrospun and collected as well-aligned fiber bundles and then twisted into yarns. Yarn weight loss, morphology changes in the yarns, and morphology changes in the fiber microstructure with degradation were evaluated. Results showed that the electrospun PCL yarns degraded slowly with a weight loss less than 3 % in 12 weeks. The addition of various concentrations of ampicillin salt increased the degradation rate slightly. The morphological changes observed in fiber microstructure suggested that the degradation underwent bulk erosion and the degradation began with the amorphous regions. Revealed by the fiber morphological changes with degradation, the microstructure of electrospun PCL fibers followed the fringed fibril fiber model. The fiber arrangement in the yarn was impaired by the in vitro degradation environment as well.  相似文献   

2.
Understanding how humans differ from other animals, as well as how we are like them, requires comparative investigations. For the purpose of documenting the distinctive features of humans, the most informative research involves comparing humans to our closest relatives–the chimpanzees and other great apes. Psychology and anthropology have maintained a tradition of empirical comparative research on human specializations of cognition. The neurosciences, by contrast, have been dominated by the model-animal research paradigm, which presupposes the commonality of "basic" features of brain organization across species and discourages serious treatment of species differences. As a result, the neurosciences have made little progress in understanding human brain specializations. Recent developments in neuroimaging, genomics, and other non-invasive techniques make it possible to directly compare humans and nonhuman species at levels of organization that were previously inaccessible, offering the hope of gaining a better understanding of the species-specific features of the human brain. This hope will be dashed, however, if chimpanzees and other great ape species become unavailable for even non-invasive research.  相似文献   

3.
Two haplotypes of the pathogen, ‘Candidatus Liberibacter solanacearum,’ (Lso) and four haplotypes of the insect vector, Bactericera cockerelli, are associated with zebra chip disease of potato. Whether disease severity or incidence is influenced by pathogen or insect haplotype is poorly understood. The role of Lso ‘A’ and ‘B,’ transmitted by three haplotypes of B. cockerelli, on disease severity and incidence in eight potato cultivars was analyzed. Both haplotypes of Lso induced tuber symptoms. In general, Lso B caused higher incidence of symptoms, and greater reduction in tubers compared with Lso A. Lso B was associated with more severe tuber symptoms, producing fewer mild or moderate tuber symptoms. Lso A was associated with less severe tuber symptoms, despite being able to induce severe symptoms. Disease incidence, tuber yield, and symptom severity ratings were not dependent upon the psyllid haplotype transmitting the pathogen, suggesting that pathogen, not insect haplotype affects Lso transmission.  相似文献   

4.
Recently proposals have been made in both Europe and North America to try to radically change potato breeding strategy from a tetraploid, heterozygous crop to a diploid inbred crop. As part of that effort, clones from the long-day adapted, late blight resistant diploid hybrid Solanum phureja – S. stenotomum population were selfed to begin the process of developing inbred lines. In March of 2016 and 2017, 42 diploid clones from the above-mentioned population were selfed in the greenhouse in Beltsville, MD. In 2016 and 2017, 10 and 13 clones failed to flower, respectively. Among the remaining clones, 716 pollinations were made in 2016, resulting in 57 fruit from 17 clones, and 3742 seeds; 801 pollinations were made in 2017, resulting in 34 fruit from 12 clones, and 1903 seeds. Nine clones were successfully selfed both years. Percent successful selfs was significantly higher in 2016 (7.96%) than in 2017 (4.24%). The most prolific clones in 2016 were BD1241–1 (34% successful selfs, 1090 seed), BD1218–3 (25% successful selfs, 638 seed), BD1215–1 (5% successful selfs, 411 seed), BD1243–1 (23% successful selfs, 232 seed). In contrast, the most prolific clones in 2017 were BD1230–2 (25% successful selfs, 537 seed), BD1203–3 (23% successful selfs, 391 seed), and BD1229–1 (11% successful selfs, 388 seed). These results indicate that there is sufficient self-compatibililty in this population to generate large numbers of inbred individuals, but that genotype x environment interactions are large. Attempts to generate selfed seed should be made over several years to maximize the genetic base of the selfed population.  相似文献   

5.
Effect of PRD (partial rootzone drying) on yield and yield components of canola (Brassica napus L.) was investigated in greenhouse conditions. The treatments were: T1, full watering of both sides of roots; T2, alternate irrigation on both sides; T3, half of irrigation water in T1 was given to one side; T4, same as T3 but without plate; T5, same as T2 but without plate. In T1, T2, and T3 treatments, the boxes were evenly separated into two compartments with thin plates. The results showed that grain yield of T1 to T5 treatments was 18.11, 16.38, 12.44, 9.29, and 8.66 g plant−1. T2 treatment increased plant height by 46.9% and 1000-seed weight by 17.8%, but reduced lateral branches by 16.7% and number of pods by 24%, over T1 treatment. T2 treatment was the most efficient (irrigation water use efficiency = 0.679 kg m−3) and treatment T5 was the least efficient (0.359 kg m−3). The difference between irrigation water use efficiency (IWUE) of T2 and T5, and T3 and T4 treatments, was significant (p < 0.05). Therefore, halving the amount of applied irrigation water and applying this water alternatively on both sides of the root zone will produce the highest IWUE. This study showed that PRD irrigation management has high influence on rooting system of canola. This phenomenon could affect nutrients uptake and consequently all aspects of plant growth and development.  相似文献   

6.
A thermoresponsive poly(VCa-co-fluorophore) hydrogel labeled with fluorescent dye was prepared using conventional radical polymerization. A poly(VCa-co-fluorophore) copolymer consisting of N-vinylcaprolactam (VCa) and 2D-π-A type pyran-based fluorescent dye (fluorophore) units behaves as a temperature-driven fluorescent thermometer. This polymer in aqueous solution underwent a phase transition at 27–45 °C. The morphology of the internal microstructure of the poly(VCa-co-fluorophore) hydrogel was observed using SEM.  相似文献   

7.
Ascophyllum nodosum is a brown seaweed that grows abundantly in the US Northeast coastal region. This study examined the seasonal variation of A. nodosum in phenolic contents and subsequent antioxidant, α-glucosidase and α-amylase inhibitory activities. A. nodosum was harvested monthly and extracted in hot water and the resulting extracts were spray-dried. The results indicate a clear seasonal variation in terms of phenolic content, with June and July being the highest (36.4 and 37 mg/g, respectively) and May the lowest (21.8 mg/g). The antioxidant activities, in terms of 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, correlated with the phenolic contents observed (r = 0.81), with the month of July being the highest (58%) and April the lowest (26%). Similarly in terms of Trolox equivalent, July had the highest activity (15.53 μM) and April and May the lowest (8.40 and 8.27 μM, respectively). α-glucosidase inhibitory activity exhibited a pattern similar to the phenolic contents observed with July having the highest inhibitory activity (IC70 2.23 μg) and April the lowest (IC70 26.13 μg), resulting in an inverse correlation between IC70 values and total phenolic content (r = −0.89). Such seasonal variation is believed to be caused by temperature-related stress considering that A. nodosum is a cold water species.  相似文献   

8.
This study was designed to examine the in vitro antimicrobial and antioxidant activities and the amount of total phenolics of the methanol extracts of Ballota rotundifolia L. and Teucrium chamaedrys C. Koch. In the case of antimicrobial activity tests, polar sub-fractions of the methanol extracts of plant species exhibited weakest antimicrobial activity when compared with the non-polar ones. While, non-polar sub-fraction of B. rotundifolia showed moderate activity against A. lwoffii, C. perfringens and the yeasts, T. chamaedrys performed excellent activity pattern against all of the tested microorganisms. The sub-fractions were also screened for their possible antioxidant activities by two complementary tests, namely DPPH free radical-scavenging and β-carotene/linoleic acid assays. Non-polar extracts of the plant species remained inactive in both test systems. On the other hand polar extracts showed remarkable antioxidant activities. In DPPH system, free radical scavenging effect of T. chamaedrys was measured as 18.00 ± 1.42 μg.mg−1. It is extremely important to point out that, polar sub-fraction of T. chamaedrys is found as effective as the positive control BHT. Non-polar sub-fraction of T. chamaedrys found to have the highest total phenolic amount (97.12 ± 1.28 μg/mg). Results obtained from this experiment confirm the relationship between the amount of phenolics and biological activities.  相似文献   

9.
Kevlar fibers were treated in three kinds of coupling agents’ solutions by Co60 γ-ray co-irradiation. After the treatment, the interlaminar shear strength (ILSS) values of Kevlar fibers/epoxy composites were all improved. Surface elements of the fibers were determined by energy dispersive X-ray microanalysis (EDX). X-ray photoelectron spectroscopy (XPS) indicated that the oxygen/carbon ratio of the treated fibers was increased and Fourier transform infrared (FT-IR) spectrum confirmed the increase in the polar groups at the fiber surface. The tensile strength of the fibers was evaluated by statistical analysis using the Weibull distribution. The wettability of the fiber surface was also enhanced by the treatment. The possible mechanisms of γ-ray co-irradiation treatment are proposed by the radical reactions. The results indicated that γ-ray co-irradiation technique modified the physicochemical properties of Kevlar fibers and improved the interfacial adhesion of its composites.  相似文献   

10.
Mucuna pruriens var. utilis, an underutilized tropical legume has a nutritional quality comparable to soya beans and other conventional legumes as it contains similar proportions of protein, lipid, minerals, and other nutrients. The beans have been traditionally used as a food in a number of countries, viz., India, Philippines, Nigeria, Ghana, Brazil, and Malawi. Recently, the velvet beans are exploited as a protein source in the diets of fish, poultry, pig, and cattle after subjected to appropriate processing methods. Although the velvet beans contain high levels of protein and carbohydrate, their utilization is limited due to the presence of a number of antinutritional/antiphysiological compounds, phenolics, tannins, L-Dopa, lectins, protease inhibitors, etc., which may reduce the nutrient utilization. Unfortunately, even though many researchers all over the world working on Mucuna, only scanty and conflicting information are available regarding its utilization as a food/feed and no scientific gathering to date has focused on the food/feed applications of Mucuna. Hence, the present review has been emphasized on the nutritional potential of this underutilized, nonconventional legume and current state of its utilization as food/feed for both human beings and livestock throughout the world.  相似文献   

11.
The kiwiberry (Actinidia arguta) is a new product on the market that is enjoying growing consumer acceptance around the world. This widespread interest has created increased demand for identification of the kiwiberry’s nutritional health benefits. Containing over 20 essential nutrients and a range of vitamins, the kiwiberry comes near the top of fruits classed as superfoods. It is one of the richest sources of vitamin C with up to 430 mg/100 g fresh weight (FW) and is considered the richest dietary source of myo-inositol (up to 982 mg/100 g FW). The kiwiberry is also one of the richest sources of lutein (up to 0.93 mg/100 g FW) in commonly consumed fruit. Furthermore, containing up to 1301.1 mg/100 g FW phenolics and significant amounts of the essential minerals of potassium, calcium and zinc, the kiwiberry rates very highly as a ‘healthy food’. The type and number of this fruit’s medicinally promising nutrients have motivated ongoing investigations into its antioxidant, anti-tumour and anti-inflammatory properties. Early research has pointed to the kiwiberry being a very promising treatment for some cancers and health issues involving the gastrointestinal system, hypercholesterolemia and certain cancers. A pharmaceutical composition of A. arguta, A. kolomikta, and A. polygama extracts has already been registered for the prevention and treatment of some immune (inflammatory) mediated diseases, as well as the treatment of some non-allergic inflammatory diseases. This paper reviews and highlights the limited nutritional and therapeutic information currently available on the kiwiberry, a minor fruit possessing such major properties.  相似文献   

12.
Camellia euphlebia (family, Theaceae) has been used for the prevention and treatment of cardiovascular diseases in Southern China. However, there has been no report on the hypolipidemic activity of Camellia euphlebia flower. This study evaluated the hypolipidemic activity of different preparation of Camellia euphlebia flower extracts using in vivo models. Mice intragastrically administered aqueous extract at 400 mg/kg dose or ethanol extract at 100 and 400 mg/kg doses of Camellia euphlebia flower for 28 days exhibited significant decreases in the levels of total cholesterol, triglycerides and low-density lipoprotein cholesterol, while displaying increased level of high-density lipoprotein cholesterol in the serum. The Camellia euphlebia flower extracts also improved the antioxidant ability of hyperlipidemic mice as well as protecting the animals against liver damage by lowering the level of glutamic-pyruvic transaminase activity. Furthermore, 400 mg/kg ethanol extract effectively down-regulated the mRNA levels of fatty acid synthase, 3-hydroxy-3-methylglutaryl CoA reductase and glycerol-3-phosphate acyl transferase, suggesting that Camellia euphlebia flower extract may potentially inhibit lipid accumulation in the liver by regulating the expression of fatty acid synthase, 3-hydroxy-3-methylglutaryl CoA reductase and glycerol-3-phosphate acyl transferase. These results provided support for the potential hypolipidemic activity of Camellia euphlebia flower and could partly explain the basis of using Camellia euphlebia for the treatment of hyperlipidemia.  相似文献   

13.
Biocompatible polyvinyl alcohol (PVA)-styrylpyridinium (SbQ)/β-cyclodextrin (β-CD) composite nanofibers were obtained by electrospinning in this study. PVA-SbQ was used as the foundation polymer as well as crosslinking agent, β-CD was incorporated to achieve expected properties such as improved mechanical properties and thermal stability. The Fourier transform infrared spectroscopy (FTIR) spectra confirmed the existence of β-CD, and the morphologies and average fiber diameters of the electrospun composite nanofibers were also analyzed by SEM. X-ray diffraction patterns (XRD) of PVA-SbQ/β-CD composite nanofibers revealed that the inclusion of β-CD in the nanofibers affected the ordered phase of PVA. Besides, the thermal analyses revealed the improvement in the thermal properties for PVA-SbQ/β-CD composite nanofibers. It was found that the crosslinked composite nanofibers showed a clear higher tensile strength (TS) as well as a greater elongation at break (EB). Eventually, antifungal drug griseofulvin (GSV) has been loaded into the composite nanofibers by formation of its inclusion complex with β-CD in aqueous solution, ultraviolet light (UV-Vis) spectral analysis showed that the drug-loading nanofibers had certain sustained release effect.  相似文献   

14.
Consistent and effective methods for early discrimination of pathogen resistance, and selection of times for tissue sampling, are important for experiments using global gene expression and metabolomics. Assays for resistance to the vascular pathogen Verticillium dahliae (Vd), the causal agent of Verticillium wilt (VW), are particularly difficult because escapes are common in field assays. Seedling dip assays offer a potential solution, but homogeneous populations are not typically available. As an alternative strategy, we have developed a protocol for studying spatiotemporal infection dynamics of Vd using potato stem cuttings. The protocol was validated using genotypes varying in resistance/susceptibility to Vd. Although there were no visual symptoms in the plants, stem sections were infested with Vd as early as 7 dpi. Symptoms were first observed in the most susceptible genotype at 10 dpi and became apparent on all test subjects at 14 dpi. The protocol has potential applications in resistance breeding and ‘omics’ studies where populations derived from true seeds are not available.  相似文献   

15.
This study evaluated the extraction of two colors of dye (yellow and brown) from Coreopsis tinctoria flower petals using ultrasound and the dyeing of leather with the extracted dyes as a source of nontoxic and eco-friendly dye. The results showed an increase in the dye extraction values with increasing time at 100 W ultrasonic power at 80 °C for 1 h. Leather dyeing was optimized with the aid of ultrasound and magnetic stirring. The optimum leather dyeing conditions, with respect to the dye uptake, dye penetration and intensity of the color, were determined to be 12 % dye concentration, 100 W power, 1,000 rpm, and pH 7.0 for 60 min at 80 °C. It was shown that sonication improves dye exhaustion from a 90 % to 60 % rating for 1 h of dyeing time. The dyed leather was assessed by reflectance measurements and compared with visual assessment data. The fastness properties of dyed leather samples showed good fastness against washing, light, and dry and wet rubbing. The strength properties were not significantly altered and the bulk properties, such as softness, were found to be improved by the use of Coreopsis tinctoria yellow and brown dyes using an ultrasonic and magnetic stirring dyeing process.  相似文献   

16.
Lacto-juices processed by lactic acid fermentation bring about a change in the beverage assortment for their high nutritive value, vitamins and minerals which are beneficial to human health when consumed. Sweet potato roots (non-boiled/ fully-boiled) were fermented with Lactobacillus plantarum MTCC 1407 at 28 ± 2°C for 48 h to make lacto- juice. During fermentation both analytical [pH, titratable acidity, lactic acid, starch, total sugar, reducing sugar (g/kg roots), total phenol and β-carotene (mg/kg roots)] and sensory (texture, taste, aroma, flavour and after taste) analyses of sweet potato lacto-juice were evaluated. The fermented juice was subjected to panelist evaluation for acceptability. There were no significant variations in biochemical constituents (pH, 2.2–3.3; lactic acid, 1.19–1.27 g/kg root; titratable acidity, 1.23–1.46 g/kg root, etc.) of lacto-juices prepared from non-boiled and fully-boiled sweet potato roots except β-carotene concentration [130 ± 7.5 mg/kg (fully-boiled roots) and 165 ± 8.1 mg/kg (non-boiled roots)]. The panelist evaluation scores ranged from 3–4.8 (in a hedonic scale of 1–5) from moderate liking to very much liking of sweet potato lacto-juice. Principal component analyses reduced the eight original analytical variables to three independent components (factors), which accounted for 99.9% of the total variations. Similarly, five original sensory variables were reduced to two independent components, which accounted for 83.1% of the total variations.  相似文献   

17.
Banana flour obtained from unripe banana (Musa acuminata, var. Nanicão) under specific drying conditions was evaluated regarding its chemical composition and nutritional value. Results are expressed in dry weight (dw). The unripe banana flour (UBF) presented a high amount of total dietary fiber (DF) (56.24 g/100 g), which consisted of resistant starch (RS) (48.99 g/100 g), fructans (0.05 g/100 g) and DF without RS or fructans (7.2 g/100 g). The contents of available starch (AS) (27.78 g/100 g) and soluble sugars (1.81 g/100 g) were low. The main phytosterols found were campesterol (4.1 mg/100 g), stigmasterol (2.5 mg/100 g) and β-sitosterol (6.2 mg/100 g). The total polyphenol content was 50.65 mg GAE/100 g. Antioxidant activity, by the FRAP and ORAC methods, was moderated, being 358.67 and 261.00 μmol of Trolox equivalent/100 g, respectively. The content of Zn, Ca and Fe and mineral dialyzability were low. The procedure used to obtain UBF resulted in the recovery of undamaged starch granules and in a low-energy product (597 kJ/100 g).  相似文献   

18.
Red arils of Pithecellobium dulce fruit, commonly known as guamuchil, show high antioxidant (AOx) and α-glucosidase inhibitory (IαG) activities, which have been mainly associated with the content of unknown anthocyanins. In this study, the AOx (i.e., DPPH and ABTS as Trolox equivalents, μmol TE/g) and IαG (as half-maximal inhibitory concentration, IC50, mg/mL) activities of the anthocyanin-rich fraction (ARF) obtained from red arils were contrasted with those of the methanol extract (ME), and the main ARF anthocyanins were characterized by HPLC-DAD-ESI-MS, GC-MS and 1H-NMR. The AOx and IαG values of the ARF (DPPH?=?597.8; ABTS?=?884.01; IαG?=?0.06) were better than those of the ME (DPPH?=?41.5; ABTS?=?142.3; IαG?=?17.5); remarkably, the ARF IαG value was about 42 times lower than that of acarbose. The main anthocyanins in ARF were pelargonidin 3-O-glucoside and cyanidin 3-O-glucoside. Thus, the consumption of red P. dulce arils could provide health benefits for prevention/treatment of chronic degenerative diseases such as diabetes.  相似文献   

19.

Background  

In spite of very low nutrient concentrations in its vicinity – both column and pore waters-, the Posidonia oceanica of the Revellata Bay displays high biomass and productivity. We measured the nutrient fluxes from the sediment into the water enclosed among the leaf shoots ("canopy water") to determine if it is possible source of nutrients for P. oceanica leaves.  相似文献   

20.
Cereals provide a good source of dietary fibre and other important compounds with nutritional potential, such as phenolic compounds, antioxidants, minerals and vitamins. Although native Andean cereals are known to have high nutritional value, their minor components have not been studied thoroughly. In this study, two varieties of a native Andean crop, kañiwa (Chenopodium pallidicaule), were investigated as sources of dietary fibre and specific antioxidant compounds. Two products, an extrudate and bran, were also prepared and their functional properties and bioactive compounds were determined. Both varieties were rich in total dietary fibre and lignin, and the phenolic components analyzed had high antioxidant activity. The extrudates had good functional properties, such as degree of gelatinization, sectional expansion index and water solubility index; the bran was high in bioactive compounds, such as total phenolics. In conclusion, kañiwa may offer an alternative to traditional cereals as a health-promoting food ingredient.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号