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 31 毫秒
1.
Tandem arrays of TTAGG repeats show a highly conserved location at the telomeres across the phylogenetic tree of arthropods. In giant water bugs Belostoma, the chromosome number changed during speciation by fragmentation of the single ancestral X chromosome, resulting in a multiple sex chromosome system. Several autosome–autosome fusions and a fusion between the sex chromosome pair and an autosome pair resulted in the reduced number in several species. We mapped the distribution of telomeric sequences and interstitial telomeric sequences (ITSs) in Belostoma candidulum (2n = 12 + XY/XX; male/female), B. dentatum (2n = 26 + X1X2Y/X1X1X2X2), B. elegans (2n = 26 + X1X2Y/X1X1X2X2), B. elongatum (2n = 26 + X1X2Y/X1X1X2X2), B. micantulum (2n = 14 + XY/XX), and B. oxyurum (2n = 6 + XY/XX) by FISH with the (TTAGG)n probes. Hybridization signals confirmed the presence of TTAGG repeats in the telomeres of all species examined. The three species with reduced chromosome numbers showed additional hybridization signals in interstitial positions, indicating the occurrence of ITS. From the comparison of all species here analyzed, we observed inverse relationships between chromosome number and chromosome size, and between presence/absence of ITS and chromosome number. The ITS distribution between these closely related species supports the hypothesis that several telomere–telomere fusions of the chromosomes from an ancestral diploid chromosome number 2n = 26 + XY/XX played a major role in the karyotype evolution of Belostoma. Consequently, our study provide valuable features that can be used to understand the karyotype evolution, may contribute to a better understanding of taxonomic relationships, and also elucidate the high plasticity of nuclear genomes at the chromosomal level during the speciation processes.  相似文献   

2.
The aim of this study was to systematically obtain a model of factors that would yield an optimized self-nanoemulsified capsule dosage form (SNCDF) of a highly lipophilic model compound, Coenzyme Q10 (CoQ). Independent variables such as amount of R-(+)-limonene (X 1), surfactant (X 2), and cosurfactant (X 3), were optimized using a 3-factor, 3-level Box-Behnken statistical design. The dependent variables selected were cumulative percentage of drug released after 5 minutes (Y 1) with constraints on drug release in 15 minutes (Y 2), turbidity (Y 3), particle size (Y 4), and zeta potential (Y 5). A mathematical relationship obtained,Y 1=78.503+6.058X 1 +13.738X 2+5.986X 3−25.831X 1 2 +9.12X 1X2−26.03X 1X3−38.67X 2 2 +11.02X 2X3−15.55X 3 3 (r 2=0.97), explained the main and quadratic effects, and the interaction of factors that affected the drug release. Response surface methodology (RSM) predicted the levels of factorsX 1,X 2, andX 3 (0.0344, 0.216, and 0.240, respectively), for a maximized response ofY 1 with constraints of >90% release onY 2. The observed and predicted values ofY 1 were in close agreement. In conclusion, the Box-Behnken experimental design allowed us to obtain SNCDF with rapid (>90%) drug release within 5 minutes with desirable properties of low turbidity and particle size.  相似文献   

3.
We used response surface methodology to optimize the preparation conditions of conjugated linoleic acid (CLA) microcapsules for maximum entrapment efficiency. Three independent variables were used: the ratio of CLA core material to agar and waxy corn starch wall material (X1), the temperature of dispersion fluid (X2), and the concentration of emulsifier (X3). The optimized values of X1, X2, and X3 were found to be 3.82:6.18, 19.97 °C, and 0.34%, respectively. The CLA oxidation stability was significantly protected by microencapsulation. These results suggest that CLA-loaded microcapsules can be used as a means to enhance not only the entrapment efficiency but also the oxidative stability of CLA.  相似文献   

4.
The aim of the present investigation was to evaluate microemulsion as a vehicle for dermal drug delivery and to develop microemulsion-based gel of terbinafine for the treatment of onychomycosis. D-optimal mixture experimental design was adopted to optimize the amount of oil (X 1), Smix (mixture of surfactant and cosurfactant; X 2) and water (X 3) in the microemulsion. The formulations were assessed for globule size (in nanometers; Y 1) and solubility of drug in microemulsion (in milligrams per milliliter; Y 2). The microemulsion containing 5.75% oil, 53.75% surfactant–cosurfactant mixture and 40.5% water was selected as the optimized batch. The globule size and solubility of the optimized batch were 18.14 nm and 43.71 mg/ml, respectively. Transmission electron microscopy showed that globules were spherical in shape. Drug containing microemulsion was converted into gel employing 0.75% w/w carbopol 934P. The optimized gel showed better penetration and retention in the human cadaver skin as compared to the commercial cream. The cumulative amount of terbinafine permeated after 12 h was 244.65 ± 18.43 μg cm−2 which was three times more than the selected commercial cream. Terbinafine microemulsion in the gel form showed better activity against Candida albicans and Trichophyton rubrum than the commercial cream. It was concluded that drug-loaded gel could be a promising formulation for effective treatment of onychomycosis.  相似文献   

5.
Polysaccharides production from Poria cocos was carried out using aqueous NaOH with the assistance of ultrasonic. Experimental design was used to investigate the effect of three parameters (extraction time, extraction concentration of NaOH, and ratio of aqueous NaOH to raw material) on polysaccharides yields. The ranges of the factors investigated were 1–3 min for extraction time (X1), 0.5–1.0 mol/L for extraction concentration of NaOH (X2), and 30–50 for ratio of aqueous NaOH to raw material (X3). The statistical analysis of the experiment indicated that extraction concentration of NaOH had significant effect on P. cocos polysaccharides yields. The central composite design showed that polynomial regression models were in good agreement with the experimental results with the coefficients of determination of 0.9935 for P. cocos polysaccharides yield. The optimal condition for P. cocos polysaccharides yield within the experimental range of the variables studied was at 2.44 min, 0.789 mol/L, and 53.0. At this condition, the predicted yield of polysaccharides extracted was 82.3%.  相似文献   

6.
Liang   《Carbohydrate polymers》2008,74(4):858-861
Experimental design was used to investigate the effect of three parameters (extraction time, extraction number and ratio of water to raw material) on polysaccharides yields. The ranges of the factors investigated were 3.5–4.5 h for extraction time (X1), 4–6 for extraction number (X2), and 25–35 for ratio of water to raw material (X3). The statistical analysis of the experiment indicated that extraction time and ratio of water to raw material had significant effect on Glycyrrhiza glabra polysaccharides yields. The central composite design showed that polynomial regression models were in good agreement with the experimental results with the coefficients of determination of 0.924 for Glycyrrhiza glabra polysaccharides yield. The optimal condition for Glycyrrhiza glabra polysaccharides yield within the experimental range of the variables studied was at 4.3 h, 6, and 35. At this condition, the predicted yield of polysaccharides extracted was 3.6%.  相似文献   

7.
The present investigation concerns with the development and optimization of an in situ forming formulation using 33 full factorial design experimentation. Metformin, an antidiabetic drug with upper part of gastrointestinal tract as absorption window was used as a model drug. The formulations were designed with an objective to retain in stomach for an extended time period. The effect of three independent factors—concentrations of sodium alginate (X 1), gellan gum (X 2), and metformin (X 3) on in vitro drug release were used to characterize and optimize the formulation. Five dependent variables—release exponent (Y 1), dissolution efficiency (Y 2), drug release at 30 min (Y 3), 210 min (Y 4), and 480 min (Y 5) were considered as optimization factors. The data were statistically analyzed using ANOVA, and a p < 0.05 was considered statistically significant. Three dimensional surface response plots were drawn to evaluate the interaction of independent variables on the chosen dependent variables. Of the prepared 27 formulations, the responses exhibited by batch F17 containing medium level sodium alginate (X 1), low level gellan (X 2), and medium level metformin (X 3) were similar to the predicted responses.  相似文献   

8.
In order to optimize and evaluate the influence of nitrogen, phosphorus, and inoculum concentrations on the biodegradation of hydrocarbon contaminated effluents, experiments based on central composite design (CCD) method were carried out for 3 days, employing C1 mixed culture and intermittent aeration. The independent variables were nitrogen concentration (X 1), phosphorus concentration (X 2), and inoculum concentration (X 3) and the removal of total petroleum hydrocarbons (TPH) was the dependent variable. The optimized nutrients ratio (C:N:P = 100:20:2.7) and inoculum concentration (1.32 g/l) provided TPH removal of 71.8% after processing for three days. Analysis using gas chromatography identified five hydrocarbons classes: paraffins, isoparaffins, olefins, naphthenics, and aromatics. The naphthenic compounds did not degrade as readily as the other hydrocarbons that were identified. The following degradation percentages were obtained: 87.1% for the paraffins, 77.7% for the isoparaffins, 78.6% for the olefins, 38.4% for the naphthenics, and 71.7% for the aromatics.  相似文献   

9.
Small‐seeded species are an integral component of many natural systems. However, small‐seeded species are often omitted from restoration projects due to limited flow through seeders, low broadcast distance, and inconsistent seeding rates. To address these problems, we developed a novel technique within a rotary coater that allows for the conglomeration of small, low‐purity seeds using a combination of clay, compost, water, and a polymer binder. We used Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis), which has a seed size of approximately 1 mm or less, as a model species to evaluate the technology. We demonstrated improved flowability of conglomerates over untreated (control) seeds through measurements of the Hausner ratio (8% decrease), the angle of repose (21% decrease), and delivery through a broadcast seeder. Seeding rates of conglomerated seed were more consistent than control seed over rugged terrain. Conglomerates were also broadcast 2.2 times further than control seed, which may mitigate the overall cost of implementing this technology. Laboratory trials demonstrated that the final germination of conglomerated seed averaged 15% higher than control seed. Field trials at two sites demonstrated that seedling emergence was similar for control and conglomerated seed. With no deleterious effects observed from the conglomeration treatment, additional research is merited for using conglomerates as a platform to apply various additives, such as fungicides, plant growth hormones, fertilizers, and biologicals. The potential outcomes of these strategies may have a significant impact on future seeding attempts by improving seed delivery and increasing overall seeding success.  相似文献   

10.
This study investigated the utility of a 23 factorial design and optimization process for polylactic-co-glycolic acid (PLGA) nanoparticles containing itraconazole with 5 replicates at the center of the design. Nanoparticles were prepared by solvent displacement technique with PLGAX 1 (10, 100 mg/mL), benzyl benzoateX 2 (5, 20 μg/mL), and itraconazoleX 3 (200, 1800 μg/mL). Particle size (Y 1), the amount of itraconazole entrapped in the nanoparticles (Y 2), and encapsulation efficiency (Y 3) were used as responses. A validated statistical model having significant coefficient figures (P<.001) for the particle size (Y 1), the amount of itraconazole entrapped in the nanoparticles (Y 2), and encapsulation efficiency (Y 3) as function of the PLGA (X 1), benzyl benzoate (X 2), and itraconazole (X 3) were developed: Y1=373.75+66.54X1+52.09X2+105.06X3−4.73X1X2+46.30X1X3; Y2=472.93+73.45X1+ 169.06X2+333.03X3+62.40X1X3+141.49X2X3; Y3= 57.36+6.53X1+15.52X2−12.59X3+1.01X1X3+ 1.73X2X3.X 1,X 2, andX 3 had a significant effect (P<.001) onY 1,Y 2, andY 3. The particle size, the amount of itraconazole entrapped in the nanoparticles, and the encapsulation efficiency of the 4 formulas were in agreement with the predictions obtained from the models (P<.05). An overlay plot for the 3 responses shows the boundary in whichY 1 shows the boundary in which a number of combinations of concentration of PLGA, benzyl benzoate, and itraconazole will result in a satisfactory process. Using the desirability approach with the same constraints, the solution composition having the highest overall desirability (D=0.769) was 10 mg/mL of PLGA, 16.94 μg/mL of benzyl benzoate, and 1001.01 μg/mL of itraconazole. This approach allowed the selection of the optimum formulation ingredients for PLGA nanoparticles containing itraconazole of 500 μg/mL.  相似文献   

11.
Oily sludge degradation by bacteria from Ankleshwar, India   总被引:7,自引:0,他引:7  
Three bacterial strains, Bacillus sp. SV9, Acinetobacter sp. SV4 and Pseudomonas sp., SV17 from contaminated soil in Ankleshwar, India were tested for their ability to degrade the complex mixture of petroleum hydrocarbons (such as alkanes, aromatics, resins and asphaltenes), sediments, heavy metals and water known as oily sludge. Gravimetric analysis showed that Bacillus sp. SV9 degraded approx. 59% of the oily sludge in 5 days at 30 °C whereas Acinetobacter sp. SV4 and Pseudomonas sp. SV17 degraded 37% and 35%. Capillary gas chromatographic analysis revealed that after 5 days the Bacillus strain was able to degrade oily sludge components of chain length C12–C30 and aromatics more effectively than the other two strains. Maximum drop in surface tension (from 70 to 28.4 mN/m) was accompanied by maximum biosurfactant production (6.7 g l−1) in Bacillus sp. SV9 after 72 h, these results collectively indicating that this bacterial strain has considerable potential for bioremediation of oily sludge.  相似文献   

12.
Ultrasonic technology was applied for polysaccharide extraction from the leaves of Dodonaea viscosa and response surface methodology (RSM) was used to optimize the effects of processing parameters on polysaccharide extraction yield. Three independent variables were extraction time (X1), extraction temperature (X2) and ultrasonic power (X3), respectively. The statistical analysis indicated the independent variables (X1, X2, X3), the quadratic terms (X11 and X33) and the interaction terms (X1X2, X1X3, X2X3) had significant effects on the yield of polysaccharides (P < 0.05). The optimal extraction conditions of D. viscosa leaf were determined as follows: extraction time 50.54 min, extraction temperature 85 °C and ultrasonic power 400 W. Under these conditions, the experimental yield of polysaccharides was 9.455 ± 0.24%, which was agreed closely with the predicted value (9.398%). The evaluation of anti-oxidant activity suggested that the polysaccharide exhibited significant protection against DPPH and hydroxyl radicals and could be explored as a nutraceutical agent.  相似文献   

13.
The kinetic and general growth features of Bacillus thuringiensis var. israelensis were evaluated. Initial glucose concentration (S 0) in fermentation media varied from 10 to 152 g/l. The results afforded to characterize four morphologically and physiologically well-defined culture phases, independent of S 0 values: Phase I, vegetative growth; Phase II, transition to sporulation; Phase III, sporulation; and Phase IV, spores maturation and cell lysis. Important process parameters were also determined. The maximum specific growth rates (μ X,m) were not affected with S 0 up to 75 g/l (1.0–1.1 per hour), but higher glucose concentrations resulted in growth inhibition by substrate, revealed by a reduction in μ X,m values. These higher S 0 values led to longer Phases III and IV and delayed sporulation. Similar biomass concentrations (X m = 15.2–15.9 g/l) were achieved with S 0 over 30.8 g/l, with increasing residual substrate, suggesting a limitation in some other nutrients and the use of glucose to form other metabolites. In this case, with S 0 from 30.8 to 152 g/l, cell yield (Y X/S ) decreased from 0.58 to 0.41 g/g. On the other hand, with S 0 = 10 g/l growth was limited by substrate, and Y X/S has shown its maximum value (0.83 g/g).  相似文献   

14.
Summary and Conclusion  An attempt was made to develop a gastroretentive drug delivery system of carbamazepine using HPMC, sodium bicarbonate, and EC as matrixing agent, gas-generating agent, and floating enhancer, respectively. A simplex lattice design was applied to investigate the combined effect of 3 formulation variables (ie, amount of HPMC (X 1), EC (X 2), and sodium bicarbonate (X 3). Results of multiple regression analysis indicated that low levels ofX 1 andX 2 and a high level ofX 3 should be used to manufacture the tablet formulation with desired in vitro floating time and dissolution. Formulation S3 was selected as a promising formulation and was found stable at 40°C temperature and 75% RH for 3 months. Published: February 9, 2007  相似文献   

15.
Aqueous biphasic systems (ABSs) are an interesting alternative for separating industrial enzymes due to easy scale-up and low operational cost. The proteases of Pseudomonas sp. M211 were purified through ABS platforms formed by polyethylene glycol (PEG) and citrate buffer salt. Two experimental designs 23 + 4 were performed to evaluate the following parameters: molar mass of PEG (MPEG), concentration of PEG (CPEG), concentration of citrate buffer (CCit), and pH. The partition coefficient (K), activity yield (Y), and purification factor (PF) were the responses analyzed. The best purification performance was obtained with the system composed of MPEG = 10,000 g/mol, CPEG = 22 wt%, CCit = 12 wt%, pH = 8.0; the responses obtained were K = 4.9, Y = 84.5%, PF = 15.1, and tie-line length = 52.74%. The purified proteases of Pseudomonas sp. (PPP) were used to obtain hydrolysates of Lupinus mutabilis (Peruvian lupin cultivar) seed protein in comparison with the commercial protease Alcalase® 2.4L. A strong correlation between hydrolysis degree and radical scavenging activity was observed, and the highest antioxidant activity was obtained with Alcalase® (1.40 and 3.47 μmol Trolox equivalent/mg protein, for 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and oxygen radical absorbance capacity, respectively) compared with PPP (0.55 and 1.03 μmol Trolox/mg protein). Nevertheless, the IC50 values were lower than those often observed for antioxidant hydrolysates from plant proteins. PEG/citrate buffer system is valuable to purify Pseudomonas proteases from the fermented broth, and the purified protease could be promising to produce antioxidant protein hydrolysates.  相似文献   

16.
Conversion of air and water into valuable chemicals of ammonia (NH3) by plasma activation and electrochemical reduction is a promising approach to achieve zero carbon-emission synthesis of NH3. However, designing highly efficient electrochemical catalysts is one of the key challenges in accomplishing this strategy. Herein, a self-supported cobalt–tungsten alloy supported on cobalt foam (CoW/CF) is developed via a simple and efficient method at room temperature. Surprisingly, the catalyst exhibits ultra-high NH3 partial current density (1559 mA cm−2), superior NH3 yield rate (164.3 mg h−1 cm−2), and high Faradaic efficiency (98.1%) under the condition of 0.2 M nitrate/nitrite, outperforming most of the reported values of electrosynthesis of NH3 to the knowledge. The introduction of W makes the Co atom surface electron deficient, which can enhance the adsorption of NOx and mitigate the excessive bonding of hydroxyl radicals (OH*) generated during nitrite (NO2*) hydrogenation, thereby reducing the energy barrier of the potential-determining step. More interestingly, a scale-up reaction system is established, achieving an NH3 yield rate of 4.771 g h−1 and successfully converting the NH3 in solution into solid NH4Cl. The aforementioned progress significantly enhances the facilitation of NH3 electrosynthesis industrialization.  相似文献   

17.
Late SG  Banga AK 《AAPS PharmSciTech》2010,11(4):1627-1635
The objective of this work was to apply response surface approach to investigate main and interaction effects of formulation parameters in optimizing novel fast disintegrating tablet formulation using β cyclodextrin as a diluent. The variables studied were diluent (β cyclodextrin, X 1), superdisintegrant (Croscarmellose sodium, X 2), and direct compression aid (Spray dried lactose, X 3). Tablets were prepared by direct compression method on B2 rotary tablet press using flat plain-face punches and characterized for weight variation, thickness, disintegration time (Y 1), and hardness (Y 2). Disintegration time was strongly affected by quadratic terms of β cyclodextrin, croscarmellose sodium, and spray-dried lactose. The positive value of regression coefficient for β cyclodextrin suggested that hardness increased with increased amount of β cyclodextrin. In general, disintegration of tablets has been reported to slow down with increase in hardness. However in the present study, higher concentration of β cyclodextrin was found to improve tablet hardness without increasing the disintegration time. Thus, β cyclodextrin is proposed as a suitable diluent to achieve fast disintegrating tablets with sufficient hardness. Good correlation between the predicted values and experimental data of the optimized formulation validated prognostic ability of response surface methodology in optimizing fast disintegrating tablets using β cyclodextrin as a diluent.  相似文献   

18.
Batch fermentative production of welan gum by Alcaligenes sp. CGMCC2428 was investigated under various oxygen supply conditions using regulating agitation speed. Based on a three kinetic parameters analysis that includes specific cell growth rate (μ), specific glucose consumption rate (q s), and specific welan formation rate (q p), a two-stage agitation speed control strategy was proposed to achieve high concentration, high yield, and high viscosity of welan. During the first 22 h, the agitation speed in 7.5 L fermenter was controlled at 800 rpm to maintain high μ for cell growth. The agitation was then reduced step-wise to 600 rpm to maintain a changing profile with stable dissolved oxygen levels and obtain high qp for high welan accumulation. Finally, the maximum concentration of welan was reached at 26.3 ± 0.89 g L−1 with a yield of 0.53 ± 0.003 g g−1 and the welan gum viscosity of 3.05 ± 0.10 Pa s, which increased by an average of 15.4, 15.2, and 20.1% over the best results controlled by constant agitation speeds.  相似文献   

19.
Simultaneously improving the stability and photoluminescence quantum yield (PLQY) of all inorganic perovskite nanocrystals (NCs) is crucial for their practical utilization in various optoelectronic devices. Here, CsPbBr3 NCs coated with polyethersulfone (PES) were prepared via an in-situ co-precipitation method. The sulfone groups in PES bind to undercoordinated lead ion (Pb2+) on the CsPbBr3 NCs, resulting in significant reduction of surface defects, thus enhancing the PLQY from 74.2% to 88.3%. Meanwhile, the PES-coated NCs exhibit high water resistance and excellent heat and light stability, maintaining over 85% of the initial PL intensity under thermal aging (70°C, 4 h) and continuous 365 nm ultraviolet (UV) light irradiation (24 W, 8 h) conditions. By contrast, the PL intensity of the control NCs dramatically dropped to less than 40%. Finally, a diode emitting bright white light was fabricated utilizing the PES-coated CsPbBr3 NCs, which exhibits a color gamut of ~110% NTSC standard.  相似文献   

20.
The purpose of this study was to load diacerein (DCR) in niosomes by applying response surface methodology and incorporate these niosomes in gel base for topical delivery. Box–Behnken design was used to investigate the effect of charge-inducing agent (X1), surfactant HLB (X2) and sonication time (X3) on the vesicle size (Y1), entrapment efficiency (Y2) and cumulative drug released (Y3). DCR niosomal formulations were prepared by thin film hydration method. The optimized formula was incorporated in different gel bases. DCR niosomal gels were evaluated for homogeneity, rheological behavior; in vitro release and pharmacodynamic activity by carrageenan-induced hind paw edema method in the rat compared with DCR commercial gel. The results revealed that the mean vesicle sizes of the prepared niosomes ranged from 7.33 to 23.72?µm and the entrapment efficiency ranged from 9.52% to 58.43% with controlled release pattern over 8?h. DCR niosomal gels exhibited pseudoplastic flow with thixotropic behavior. The pharmacodynamic activity of DCR niosomal gel in 3% HPMC showed significant, 37.66%, maximum inhibition of edema size in comparison with 20.83% for the commercial gel (p?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