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1.
Anim Biotechnol ; 33(2): 369-391, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32744150

RESUMEN

Medicinal plants exhibit colossal impact on poultry industries by improving its performance and productivity. However, some of these plants show adverse influence too by decreasing egg production percentage, egg mass, and microbiota counts. Green tea, nettle, pennyroyal, yarrow, and alfalfa in the form of seed, powder, and extract had vast potentiality to improve immunity, reduce the growth of pathogenic microbes, and improve the viable counts of lactic acid bacteria. Lavender, Alfalfa, and Nettle powder were able to improve egg yolk color. Furthermore, ginger reduced fat content in meat and increased color intensity. Flax seed increased alpha linolenic acid content in tissue, and increased n-3 fatty acid content in breast as well as thigh tissue. Physiological assessment showed that green tea, lavender, nettle, pennyroyal, and yarrow improved poultry immunity. Lavender and nettle improved internal organ traits. Interestingly, the use of flaxseed improved quail egg hatchability. Plants metabolites, particularly carvacrol and thymol showed its pivotal role as natural growth promoters by affecting growth performances, nutrient bioavailability, and immunity of broiler chickens. Additionally, in recent years, micro-encapsulation or nano-encapsulation of plant extracts and its metabolites improved growth performances of broiler chickens, thereby suggested wide utilization of this technique as a potential alternative to antibiotic growth promoters in future. This review sheds a light on beneficial as well as no adverse effects of some of the direct-fed important medicinal plants and its metabolites in poultry nutrition in order to suggest its key role in future poultry enterprise.


Asunto(s)
Pollos , Plantas Medicinales , Alimentación Animal/análisis , Animales , Pollos/metabolismo , Dieta/veterinaria , Suplementos Dietéticos , Aves de Corral
2.
Environ Toxicol ; 34(4): 388-400, 2019 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-30578595

RESUMEN

The present study aimed (1) to investigate the chemical composition as well as the anti-inflammatory properties and in vitro antioxidant activity of Citrus aurantium peel essential oil (pEOCa) and (2) to evaluate its potential effect in vivo. The main results showed that the major components of pEOCa are Limonene and Linalool. Additionally, DPPH scavenging ability and ß-carotene bleaching inhibition tests confirmed the antioxidant capacity of pEOCa. Our oil reduced the production of NO by LPS-stimulated RAW264,7 macrophages in a concentration-dependent. This inhibition occurred at a transcriptional level. pEOCa in CCl4 treated rats alleviated hepatotoxicity as monitored by the improvement of hepatic oxidative stress biomarkers levels plasma biochemical parameters, and DNA molecule aspect. Furthermore, the mRNA gene expression of Cu-Zn SOD, CAT, and GPx increased under CCl4 + pEOCa exposure to reach the same value to the control. Similarly, antioxidant activities of these three enzymes changed in accordance with the mRNA levels. These results were confirmed by the histological results. It seems obvious that the treatment with pEOCa prevented liver damage induced by CCl4 , thus preventing the harmful effects of free radicals.


Asunto(s)
Antiinflamatorios/farmacología , Antioxidantes/metabolismo , Enfermedad Hepática Inducida por Sustancias y Drogas/prevención & control , Citrus/química , Aceites Volátiles/farmacología , Estrés Oxidativo/efectos de los fármacos , Animales , Antiinflamatorios/aislamiento & purificación , Tetracloruro de Carbono/toxicidad , Enfermedad Hepática Inducida por Sustancias y Drogas/inmunología , Enfermedad Hepática Inducida por Sustancias y Drogas/patología , Relación Dosis-Respuesta a Droga , Masculino , Ratones , Aceites Volátiles/aislamiento & purificación , Células RAW 264.7 , Ratas
3.
Adv Exp Med Biol ; 1000: 333-353, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-29098629

RESUMEN

It is known that moderate exercise can prevent the development of cardiovascular diseases, but the exact molecular mechanisms mediating cardioprotective effect of exercise remain unknown. Emerging evidence suggests that exercise has great impact on the biogenesis of exosomes, which have been found in both interstitial fluid and circulation, and play important roles in cellular communication. Exosomes carry functional molecules such as mRNAs, microRNA, and specific proteins, which can be used in the early diagnosis and targeted therapy of a variety of diseases. Our review focus on the current knowledge on exosome production, secretion, uptake and how exercise influence exosome content. We also highlight recent research development in exosome based approach for cardiac repair.


Asunto(s)
Enfermedades Cardiovasculares/fisiopatología , Ejercicio Físico/fisiología , Exosomas/genética , MicroARNs/genética , Adaptación Fisiológica/genética , Adaptación Fisiológica/fisiología , Animales , Biomarcadores/metabolismo , Enfermedades Cardiovasculares/genética , Enfermedades Cardiovasculares/metabolismo , Exosomas/metabolismo , Regulación de la Expresión Génica , Humanos
4.
Toxicol Ind Health ; 32(4): 694-706, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-24215067

RESUMEN

This study aimed to investigate the antioxidant properties of different fractions obtained from the fruits of Lawsonia inermis, a widely used medicinal plant, against carbon tetrachloride (CCl4)-induced oxidative stress in rat liver. The results show that several fractions obtained from L. inermis fruits possessed important antioxidant activity. Among them, the ethyl acetate (EA) fraction showed the highest antioxidant activity. Then, EA fraction was selected for the purification of potential antioxidant compounds. The hepatoprotective effects of EA fraction and its most active constituent, gallic acid (GA), were evaluated against CCl4-induced hepatotoxicity in rats. CCl4 induced oxidative stress by a significant rise in serum marker enzymes. However, pretreatment of rats with EA fraction of fruits of L. inermis at a dose of 250 mg kg(-1)body weight and GA significantly lowered some serum biochemical parameters (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase) in treated rats. A significant reduction in hepatic thiobarbituric acid reactive substances and an increase in antioxidant enzymes namely superoxide dismutase, catalase, and glutathione peroxidase by treatment with plant extract and GA, against CCl4-treated rats, were observed. Histopathological examinations showed extensive liver injuries, characterized by extensive hepatocellular necrosis, vacuolization, and inflammatory cell infiltration. This potential antioxidant activity is comparable to those of the major purified antioxidant compound, GA. Based on these results, it was observed that fruits of L. inermis protect liver from oxidative stress induced by CCl4 and thus help in evaluation of traditional claim on this plant.


Asunto(s)
Antioxidantes/farmacología , Lawsonia (Planta)/química , Hígado/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Extractos Vegetales/farmacología , Acetatos , Animales , Antioxidantes/química , Tetracloruro de Carbono , Enfermedad Hepática Inducida por Sustancias y Drogas/patología , Flavonoides/análisis , Flavonoides/química , Frutas/química , Peroxidación de Lípido/efectos de los fármacos , Hígado/patología , Masculino , Fenoles/análisis , Fenoles/química , Extractos Vegetales/química , Ratas , Ratas Wistar
5.
Prep Biochem Biotechnol ; 45(5): 421-9, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-24840672

RESUMEN

In this work, corncob acid hydrolysate and its simulated medium whose sugar composition was the same as the corncob acid hydrolysate were used as fermentation substrate for lipid production by oleaginous yeast Trichosporon dermatis. On the corncob acid hydrolysate, after 7 days of fermentation, the biomass, lipid content, lipid yield, and lipid coefficient of T. dermatis were 17.3 g/L, 40.2%, 7.0 g/L, and 16.5%, respectively. Interestingly, during the lipid fermentation on the corncob acid hydrolysate, glucose, xylose, arabinose, and even acetic acid could be well utilized as carbon sources by T. dermatis. Surprisingly, the lipid yield (7.0 g/L) of T. dermatis on the corncob acid hydrolysate was much higher than that (3.8 g/L) on the simulated medium, in spite of the fact that the lipid coefficient (17.4%) on the simulated medium was a little higher. This phenomenon further showed that lignocellulosic acid hydrolysate was a suitable substrate for lipid fermentation by T. dermatis. This work would help the comprehensive utilization of lignocellulosic biomass for lipid production.


Asunto(s)
Microbiología Industrial/métodos , Metabolismo de los Lípidos , Trichosporon/metabolismo , Zea mays , Carbohidratos/análisis , Carbono/metabolismo , Fermentación , Hidrólisis , Lignina/química , Lípidos/análisis , Lípidos/química , Nitrógeno/metabolismo , Trichosporon/crecimiento & desarrollo
6.
Vaccines (Basel) ; 11(4)2023 Mar 23.
Artículo en Inglés | MEDLINE | ID: mdl-37112631

RESUMEN

Population-wide vaccination is the most promising long-term COVID-19 disease management strategy. However, the protection offered by the currently available COVID-19 vaccines wanes over time, requiring boosters to be periodically given, which represents an unattainable challenge, especially if it is necessary to apply several doses per year. Therefore, it is essential to design strategies that contribute to maximizing the control of the pandemic with the available vaccines. Achieving this objective requires knowing, as precisely and accurately as possible, the changes in vaccine effectiveness over time in each population group, considering the eventual dependence on age, sex, etc. Thus, the present work proposes a novel approach to calculating realistic effectiveness profiles against symptomatic disease. In addition, this strategy can be adapted to estimate realistic effectiveness profiles against hospitalizations or deaths. All such time-dependent profiles allow the design of improved vaccination schedules, where each dose can be administrated to the population groups so that the fulfillment of the containment objectives is maximized. As a practical example for this analysis, vaccination against COVID-19 in Mexico was considered. However, this methodology can be applied to other countries' data or to characterize future vaccines with time-dependent effectiveness values. Since this strategy uses aggregated observational data collected from massive databases, assumptions about the data validity and the course of the studied epidemic could eventually be necessary.

7.
J Mol Neurosci ; 71(4): 702-712, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33403591

RESUMEN

Previous evidence has shown a link between neurodegenerative diseases, including Parkinson's disease (PD), and melatonin. The data in the literature about the impact of the hormone under different experimental PD conditions are quite controversial, and its effect on memory impairment in the disease is very poorly explored. The current research was aimed at investigating the role of melatonin pretreatment on memory and motor behavior in healthy rats and those with the partial 6-hydroxydopamine (6-OHDA) model of PD. All rodents were pretreated with melatonin (20 mg/kg, intraperitoneally) for 5 days. At 24 h and 7 days after the first treatment for healthy rats, and at the second and third week post-lesion for those with PD, the animals were tested behaviorally (apomorphine-induced rotations, rotarod, and passive avoidance tests). The neurochemical levels of dopamine (DA), acetylcholine (ACh), noradrenaline (NA), and serotonin (Sero) in the brain were also determined. The results showed that in healthy animals, melatonin pretreatment had amnestic and motor-suppressive effects and did not change the levels of measured brain neurotransmitters. In animals with PD, melatonin pretreatment exerted a neuroprotective effect, manifested as a significantly decreased number of apomorphine-induced rotations, reduced number of falls in the rotarod test, and improved memory performance. The brain DA and ACh concentrations in the same animals were restored to the control levels, and those of NA and Sero did not change. Our results demonstrate a beneficial effect of melatonin on memory and motor disturbance in 6-OHDA-lesioned rats.


Asunto(s)
Antiparkinsonianos/uso terapéutico , Melatonina/uso terapéutico , Memoria , Movimiento , Enfermedad de Parkinson/tratamiento farmacológico , Animales , Antiparkinsonianos/administración & dosificación , Antiparkinsonianos/farmacología , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Masculino , Melatonina/administración & dosificación , Melatonina/farmacología , Neurotransmisores/metabolismo , Oxidopamina/toxicidad , Enfermedad de Parkinson/etiología , Ratas , Ratas Wistar
8.
Carbohydr Polym ; 270: 118350, 2021 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-34364598

RESUMEN

In this study, bacterial cellulose was synthesized by Taonella mepensis from traditional Chinese medicinal herb residues hydrolysate. To overcome the inhibitory effect of fermentation environment, in-situ fermentation with gellan gum adding was carried out for the first time. After 10 days' static fermentation, both high-acyl gellan gum and low-acyl gellan gum adding showed certain beneficial effects for bacterial cellulose production that the highest bacterial cellulose yield (0.866 and 0.798 g/L, respectively) was 59% and 47% higher than that (0.543 g/L) without gellan gum adding. Besides, gellan gum based bacterial cellulose showed some better texture characteristics. Gellan gum was loaded in the nano network of bacterial cellulose, and gellan gum adding had some influence on the crystal structure and thermal degradation behaviors of bacterial cellulose but affected little on its functional groups. Overall, this in-situ fermentation technology is attractive for bacterial cellulose production from low-cost but inhibitory substrates.


Asunto(s)
Celulosa/biosíntesis , Polisacáridos Bacterianos/biosíntesis , Rhodospirillaceae/metabolismo , Celulosa/química , China , Fermentación , Hidrólisis , Medicina Tradicional China , Microscopía Electrónica de Rastreo/métodos , Plantas Medicinales/química , Polisacáridos Bacterianos/química , Espectroscopía Infrarroja por Transformada de Fourier/métodos
9.
ACS Appl Mater Interfaces ; 10(48): 41257-41267, 2018 Dec 05.
Artículo en Inglés | MEDLINE | ID: mdl-30383360

RESUMEN

The poor sulfur tolerance of conventional nickel cermet anodes is particularly concerning for solid oxide fuel cell technology. Herein, we report an innovative anode composed of a samaria-doped ceria (SDC) scaffold and a perovskite La0.35Ca0.50TiO3-δ thin film with a surface modified with strongly coupled and in situ-formed Ni nanoparticles; the anode was prepared via an infiltration-calcination-reduction method. The rational design of such an anode transforms the detrimental effect of sulfur on the cell performance (poisoning) of state-of-the-art Ni cermet anodes into a beneficial effect promoting power generation from H2. A cell with a Ni + SDC cermet anode and a Ba0.5Sr0.5Co0.8Fe0.2O3-δ cathode showed an 18.3% reduction in the power output at 800 °C when the fuel gas was switched from pure H2 to H2-1000 ppm H2S, while a similar cell with this innovative anode showed a power output enhancement of 6.6%. Furthermore, the operational stability was significantly improved. The perovskite phase was found to account for the improved cell power output in the presence of sulfur impurity. The introduction of the nickel nanoparticles further significantly enhanced the electrode activity, while the strong coupling effect of exsolved nickel nanoparticles with the perovskite thin film improved the sulfur tolerance of the nickel phase. As a result, the anode showed both high activity and stability while operating on H2 fuel with high concentration of H2S (1000 ppm). The promoting effect of sulfur on the power generation over the perovskite anode is also discussed.

10.
Probiotics Antimicrob Proteins ; 9(1): 22-31, 2017 03.
Artículo en Inglés | MEDLINE | ID: mdl-27655068

RESUMEN

Apis mellifera L. is one of the most important natural pollinators of significant crops and flowers around the world. It can be affected by different types of illnesses: american foulbrood, nosemosis, varroasis, viruses, among others. Such infections mainly cause a reduction in honey production and in extreme situations, the death of the colony. Argentina is the world's second largest honey exporter and the third largest honey producer, after China and Turkey. Given both the prominence of the honey bee in nature and the economic importance of apiculture in Argentina and the world, it is crucial to develop efficient and sustainable strategies to control honey bee diseases and to improve bee colony health. Gram-positive bacteria, such as lactic acid bacteria, mainly Lactobacillus, and Bacillus spp. are promising options. In the Northwest of Argentina, several Lactobacillus and Bacillus strains from the honey bee gut and honey were isolated by our research group and characterized by using in vitro tests. Two strains were selected because of their potential probiotic properties: Lactobacillus johnsonii CRL1647 and Bacillus subtilis subsp. subtilis Mori2. Under independent trials with both experimental and commercial hives, it was determined that each strain was able to elicit probiotic effects on bee colonies reared in the northwestern region of Argentina. One result was the increase in egg-laying by the queen which therefore produced an increase in bee number and, consequently, a higher honey yield. Moreover, the beneficial bacteria reduced the incidence of two important bee diseases: nosemosis and varroosis. These results are promising and extend the horizon of probiotic bacteria to the insect world, serving beekeepers worldwide as a natural tool that they can administer as is, or combine with other disease-controlling methods.


Asunto(s)
Abejas/microbiología , Bacterias Grampositivas/aislamiento & purificación , Probióticos/aislamiento & purificación , Animales , Argentina , Apicultura , Abejas/crecimiento & desarrollo , Tracto Gastrointestinal/microbiología , Bacterias Grampositivas/clasificación , Bacterias Grampositivas/genética , Bacterias Grampositivas/crecimiento & desarrollo , Miel/microbiología , Probióticos/clasificación
11.
Front Plant Sci ; 8: 1767, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-29075280

RESUMEN

Aluminum (Al) is the most abundant metal in the earth's crust, but its availability depends on soil pH. Despite this abundance, Al is not considered an essential element and so far no experimental evidence has been put forward for a biological role. In plants and other organisms, Al can have a beneficial or toxic effect, depending on factors such as, metal concentration, the chemical form of Al, growth conditions and plant species. Here we review recent advances in the study of Al in plants at physiological, biochemical and molecular levels, focusing mainly on the beneficial effect of Al in plants (stimulation of root growth, increased nutrient uptake, the increase in enzyme activity, and others). In addition, we discuss the possible mechanisms involved in improving the growth of plants cultivated in soils with acid pH, as well as mechanisms of tolerance to the toxic effect of Al.

12.
EFSA J ; 15(8): e04970, 2017 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32625631

RESUMEN

EFSA requested its Scientific Committee to prepare a guidance document providing generic issues and criteria to consider biological relevance, particularly when deciding on whether an observed effect is of biological relevance, i.e. is adverse (or shows a beneficial health effect) or not. The guidance document provides a general framework for establishing the biological relevance of observations at various stages of the assessment. Biological relevance is considered at three main stages related to the process of dealing with evidence: Development of the assessment strategy. In this context, specification of agents, effects, subjects and conditions in relation to the assessment question(s): Collection and extraction of data; Appraisal and integration of the relevance of the agents, subjects, effects and conditions, i.e. reviewing dimensions of biological relevance for each data set. A decision tree is developed to assist in the collection, identification and appraisal of relevant data for a given specific assessment question to be answered.

14.
J Ethnopharmacol ; 177: 101-10, 2016 Jan 11.
Artículo en Inglés | MEDLINE | ID: mdl-26626487

RESUMEN

ETHNOPHARMACOLOGICAL RELEVANCE: Glycyrrhizae radix (GR) is a medicinal herb extensively used in traditional Chinese medicine. This study aimed to evaluate the pharmacological effect of GR and the possible mechanisms of GR, to provide a pharmacological basis in traditional medicine. MATERIALS AND METHODS: In the present study, C. elegans (L1-larvae to young adults) was exposed to 0.12-0.24 g/mL of GR in 12-well sterile tissue culture plates at 20°C in the presence of food. Lethality, growth, lifespan, reproduction, locomotion, metabolism, intestinal autofluorescence, and reactive oxygen species (ROS) production assays were performed to investigate the possible safety profile and beneficial effects of GR in these nematodes. We found that the lifespan of nematodes exposed to 0.18-0.24 g/mL of GR was extended. We then determined the mechanism of the longevity effect of GR using quantitative reverse transcription PCR and oxidative stress resistance assays induced by heat and paraquat. RESULTS: Prolonged exposure to 0.12-0.24 g/mL of GR did not induce lethality, alter body length, morphology or metabolism, affect brood size, locomotion, the development of D-type GABAergic motor neurons, or induce significant induction of intestinal autofluorescence and intestinal ROS production. In C. elegans, pretreatment with GR suppressed the damage due to heat-stress or oxidative stress induced by paraquat, a ROS generator, on lifespan, and inhibited the induction of intestinal ROS production induced by paraquat. Moreover, prolonged exposure to GR extended lifespan, increased locomotion and decreased intestinal ROS production in adult day-12 nematodes. Furthermore, prolonged exposure to GR significantly altered the expression patterns of genes encoding the insulin-like signaling pathway which had a key role in longevity control. Mutation of daf-16 gene encoding the FOXO transcription factor significantly decreased lifespan, suppressed locomotion, and increased intestinal ROS production in GR exposed adult nematodes. CONCLUSIONS: GR is relatively safe and has protective effects against the damage caused by both heat-stress and oxidative stress at the examined concentrations. Furthermore, GR is capable of extending the lifespan of nematodes, and the insulin-like signaling pathway may play a crucial role in regulating the lifespan-extending effects of GR.


Asunto(s)
Caenorhabditis elegans/efectos de los fármacos , Glycyrrhiza/química , Longevidad/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Extractos Vegetales/farmacología , Raíces de Plantas/química , Animales , Regulación de la Expresión Génica/efectos de los fármacos , Calor , Mutación , Extractos Vegetales/química , Proteínas/genética , Proteínas/metabolismo , Transducción de Señal
15.
Front Microbiol ; 7: 2084, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-28066397

RESUMEN

According to text book definition, parasites reduce the fitness of their hosts whereas mutualists provide benefits. But biotic and abiotic factors influence symbiotic interactions, thus under certain circumstances parasites can provide benefits and mutualists can harm their host. Here we addressed the question which intrinsic biotic factors shape a symbiosis and are crucial for the outcome of the interaction between the obligate intranuclear bacterium Holospora caryophila (Alphaproteobacteria; Rickettsiales) and its unicellular eukaryotic host Paramecium biaurelia (Alveolata; Ciliophora). The virulence of H. caryophila, i.e., the negative fitness effect on host division and cell number, was determined by growth assays of several P. biaurelia strains. The performances of genetically identical lines either infected with H. caryophila or symbiont-free were compared. Following factors were considered as potentially influencing the outcome of the interaction: (1) host strain, (2) parasite strain, and (3) growth phases of the host. All three factors revealed a strong effect on the symbiosis. In presence of H. caryophila, the Paramecium density in the stationary growth phase decreased. Conversely, a positive effect of the bacteria during the exponential phase was observed for several host × parasite combinations resulting in an increased growth rate of infected P. biaurelia. Furthermore, the fitness impact of the tested endosymbionts on different P. biaurelia lines was not only dependent on one of the two involved strains but distinct for the specific combination. Depending on the current host growth phase, the presence of H. caryophila can be harmful or advantageous for P. biaurelia. Thus, under the tested experimental conditions, the symbionts can switch from the provision of benefits to the exploitation of host resources within the same host population and a time-span of less than 6 days.

16.
Indian J Pharm Sci ; 77(1): 103-7, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25767325

RESUMEN

The aim of the study was to elucidate the therapeutic effects of Atracylodes rhizome polysaccharide on adenine-induced chronic renal failure in rats. Fifty male Sprague Dawley rats were selected and randomly divided in to 5 groups (n=10 rats per group): The normal control group, the chronic renal failure pathological control group, the dexamethasone treatment group and two Atracylodes rhizome polysaccharide treatment groups, treated with two different concentrations of the polysaccharide, the Atracylodes rhizome polysaccharide high group and the Atracylodes rhizome polysaccharide low group. All the rats, except those in the normal control group were fed adenine-enriched diets, containing 10 g adenine per kg food for 3 weeks. After being fed with adenine, the dexamethasone treatment group, Atracylodes rhizome polysaccharide high group and Atracylodes rhizome polysaccharide low group rats were administered the drug orally for 2 weeks. On day 35, the kidney coefficient of the rats and the serum levels of creatinine, blood urea nitrogen, total protein and hemalbumin were determined. Subsequent to experimentation on a model of chronic renal failure in rats, the preparation was proven to be able to reduce serum levels of creatinine, blood urea nitrogen and hemalbumin levels (P<0.05) and improve renal function. Atracylodes rhizome polysaccharide had reversed the majority of the indices of chronic renal failure in rats.

17.
Nanoscale Res Lett ; 10(1): 423, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26510444

RESUMEN

Annealing or growth at high temperatures for an extended period of time is considered detrimental for most synthetic strategies for high-quality Mn-doped II-VI semiconductor nanocrystals. It can lead to the broadening of size distribution and, more importantly, to the loss of dopants. Here, we examine how ripening can be beneficial to doping in a simple "heat-up" approach, where high dopant concentrations can be achieved. We discuss the interplay of the loss of dopants, Ostwald ripening, and the clustering of Mn near the surface during nanocrystal growth. Smaller nanocrystals in a reaction batch, on average, exhibit higher undesirable band-edge photoluminescence (PL) and lower desirable dopant PL. The optimization of dopant loss and the removal of such smaller undesirable nanocrystals through Ostwald ripening along with surface exchange/passivation to remove Mn clustering lead to high Mn PL quantum yields (45 to 55 %) for ZnSxSe1-x, ZnS, CdS, and CdSxSe1-x host nanocrystals. These results provide an improved understanding of the doping process in a simple and potentially scalable synthetic strategy for achieving "pure" and bright dopant emission.

18.
Asian Pac J Trop Biomed ; 1(5): 353-8, 2011 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-23569792

RESUMEN

OBJECTIVE: To investigate the antidiabetic properties of aqueous extract of stem bark of Afzelia africana (A. africana) and its beneficial effect on haematological parameters in streptozotocin induced diabetic rats. METHODS: A total of 30 rats including 24 diabetic and 6 normal rats were used for this study. Diabetes was induced in male Wistar rats by intraperitoneal injection of streptozotocin. After being confirmed diabetic, animals were orally treated with distilled water or extracts at 100 or 200 mg/kg body weight daily for 10 days. The haematological parameters including red blood and white blood cells and their functional indices were evaluated in diabetic treated groups compared with the controls. RESULTS: The extract significantly reduced the blood glucose levels while the best result was obtained at 200 mg/kg body weight. The feed and water intake in diabetic rats were significantly reduced while weight loss was minimized at both dosages. Similarly, the levels of red blood, white blood cells and their functional indices were significantly improved after extract administration at both doses. CONCLUSIONS: It can be concluded that the aqueous extract of bark of A. africana possesses antihyperglycemic properties. In addition, the extract can prevent various complications of diabetes and improve some haematological parameters. Further experimental investigation is needed to exploit its relevant therapeutic effect to substantiate its ethnomedicinal usage.


Asunto(s)
Glucemia/efectos de los fármacos , Peso Corporal/efectos de los fármacos , Diabetes Mellitus Experimental , Fabaceae/química , Hipoglucemiantes/farmacología , Corteza de la Planta/química , Extractos Vegetales/farmacología , Animales , Ingestión de Líquidos/efectos de los fármacos , Ingestión de Alimentos/efectos de los fármacos , Masculino , Ratas Wistar
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