Evaluation of carrier density and mobility in Mn ion-implanted GaAs:Zn nanowires by Raman spectroscopy.

The fabrication of complex nanoscale electronics with reduced dimensions poses challenges on novel techniques to accurately determine fundamental electronic parameters. In this article, we present a universal contactless method based on Raman scattering for measuring the mobility and hole concentration independently in GaAs:Zn and Mn ion-implanted GaAs:Zn nanowires, potentially of great interest for spintronics applications. Clear coupled longitudinal optical phonon-plasmon modes were recorded and fitted with a dielectric function, based on the Drude model, which includes contributions from both plasmons and phonons. From the fitting, we extract accurate values of the plasma frequency and plasma damping constant from which we directly calculate the hole density and mobility, respectively. The extracted mobilities were also used as input data for analysis of complementary four-probe transport measurements, where the corresponding hole concentrations could be calculated and found to be in good agreement with those extracted directly from the Raman data. We also investigated the influence of annealing of the GaAs:Zn nanowires on the hole concentration and mobility and found strong indications of thermally activated defects related to a formed crystalline As/oxide shell around the nanowires. The method proposed here is extremely powerful for the characterization of nanoelectronics in general, and nanospintronics in particular for which Hall measurements are difficult to pursue due to problems related to contact formation, as well as to inherent magnetic properties of the devices.

Raman characterization of single-crystalline Ga0.96Mn0.04As:Zn nanowires realized by ion-implantation.

Recent progress in the realization of magnetic GaAs nanowires (NWs) doped with Mn has attracted a lot of attention due to their potential application in spintronics. In this work, we present a detailed Raman investigation of the structural properties of Zn doped GaAs (GaAs:Zn) and Mn-implanted GaAs:Zn (Ga0.96Mn0.04As:Zn) NWs. A significant broadening and redshift of the optical TO and LO phonon modes are observed for these NWs compared to as-grown undoped wires, which is attributed to strain induced by the Zn/Mn doping and to the presence of implantation-related defects. Moreover, the LO phonon modes are strongly damped, which is interpreted in terms of a strong LO phonon-plasmon coupling, induced by the free hole concentration. Moreover, we report on two new interesting Raman phonon modes (191 and 252 cm-1) observed in Mn ion-implanted NWs, which we attribute to Eg (TO) and A1g (LO) vibrational modes in a sheet layer of crystalline arsenic present on the surface of the NWs. This conclusion is supported by fitting the observed Raman shifts for the SO phonon modes to a theoretical dispersion function for a GaAs NW capped with a dielectric shell.

Effects of Diet-Induced Obesity and Deficient in Vitamin D on Spermatozoa Function and DNA Integrity in Sprague-Dawley Rats.

Obesity has adverse effects on male fertility and usually is diagnosed with a prevalence of vitamin D deficiency (VD-). Discussion on the impact of obesity/VD- on sperm function has been limited. This study analyzed the effects of diet-induced obesity/VD- on viability and plasma membrane integrity (PMI), superoxide anion (O2 -) level, and DNA fragmentation (DNAfrag) in sperm Sprague-Dawley rats. The males were randomized into four groups and fed for a period of 12 weeks: G1: control diet with vitamin D (C/VD+), G2: control diet without vitamin D (C/VD-), G3: high-fat diet with vitamin D (HF/VD+), and G4: high-fat diet without vitamin D (HF/VD-). Sperm function parameters were analyzed by flow cytometry. PMI percentages and O2 - levels were not affected by any of the diets. DNA fragmentation was increasing significantly (p<0.05) in the spermatozoa of animals with diets vitamin D deficient (G2) and diet-induced obesity (G4). Our results allow us to point out that diet-induced obesity and VD- produce greater damage in DNA sperm of rats. The use of nutraceuticals containing vitamin D could be reducing the risk of fragmentation of DNA in spermatozoa.

Role of vitamin D in the development of obesity / Rol de la vitamina D en el desarrollo de la obesidad

SUMMARY: Antecedents in the literature suggest that vitamin D (VD) play a role in overweigh/obesity. The present study evaluated the effect of VD deficiency diet intake and fat hight on overweight/obesity about white adipose tissue (WAT) and body mass (BM) gain. Animals were divided into four experimental groups according to the lipid and VD content of their diets; G1: CVD+ (C: control diet with VD+; n=5), G2: CVD- (control diet without VD-; n=5), G3: HFVD+ (high fat diet, with VD+; n=5), G4: HFVD- (HF diet without VD-; n=5). The diets were administered for three months and BW was monitored weekly. At the end of this period all animals were euthanized. Epididymal (EFM), retroperitoneal (RFM) and subcutaneous (SFM) fat mass were removed, weighted. At 12 weeks the body mass of the animals that were fed without VD- diets; G2: 507.60±17.31 g, and G4: 528.50±13.50 g were significantly higher (p < 0.05), than the counterparts G1: 485.0±11.29 g and G3: 521.20±26.20 g respectively. Similarly, the animals fed with VDdiets had a greater EFM and SFM (p < 0.05) compared with the respective controls (VD+). Nevertheless, the animals fed with high fat diet had equal RFM (G3: 12.2±4.10 g, G4: 12.88±2.3 g, p > 0.05). The results demonstrate that the nutrition of rats with diet deficient in VD and high fat, promotes overweight by increasing fat deposits, suggestion a cause-effect relationship between VD deficiency and overweight. These results suggest that VD deficiency increases the risk of visceral fat obesity in males.

RESUMEN: Los antecedentes de la literatura sugieren una relación entre la vitamina D (VD) y el sobrepeso/obesidad, sin embargo, causalidad de la relación no está clara. El presente estudio evaluó el efecto de la ingesta dietética deficiente de VD y alta en grasa sobre el tejido adiposo (TA) y la masa corporal (MC). Los animales se dividieron en cuatro grupos experimentales de acuerdo con el contenido de VD y lípido en la dieta; G1: CVD+ (C: dieta control con VD+; n = 5), G2: CVD- (dieta control sin VD-; n = 5), G3: HFVD+ (dieta alta en grasa, con VD+; n = 5), G4: HFVD- (dieta HF sin VD-; n = 5). Las dietas se administraron durante tres meses y MC se controló semanalmente. Al final de este período, los animales fueron sacrificados. La masa grasa epididimaria (MGE), subcutánea abdominal (MGS) y retroperitoneal (MGR) fueron diseccionadas y pesadas individualmente. A las 12 semanas, la MC de los animales alimentados con dietas sin VD-; G2: 507,60 ± 17,31 g, y G4: 528,50 ± 13,50 g fue significativamente mayor (p < 0,05), que sus homólogos G1: 485,0 ± 11,29 g y G3: 521,20 ± 26,20 g respectivamente. De forma similar, los G2 y G4 tuvieron una mayor MGE y MGS (p < 0,05) en comparación con los controles respectivos (VD+). Sin embargo, los animales alimentados con dieta alta en grasas tuvieron igual MGR (G3: 12,2 ± 4,10 g; G4: 12,88 ± 2,3 g, p > 0,05). Los resultados demuestran que la nutrición de ratas con dieta deficiente en VD y alta en grasa, promueve el sobrepeso/obesidad al exacerbar la ganancia de masa grasa en los diferentes depósitos de grasa, sugiriendo una relación causa-efecto entre la deficiencia de VD y el sobrepeso/obesidad. Estos resultados sugieren que la deficiencia de VD aumenta el riesgo de obesidad de grasa visceral en machos.

The nature, origin and modification of insoluble organic matter in chondrites, the possibly interstellar source of Earth's C and N.

All chondrites accreted ~3.5 wt.% C in their matrices, the bulk of which was in a macromolecular solvent and acid insoluble organic material (IOM). Similar material to IOM is found in interplanetary dust particles (IDPs) and comets. The IOM accounts for almost all of the C and N in chondrites, and a significant fraction of the H. Chondrites and, to a lesser extent, comets were probably the major sources of volatiles for the Earth and the other terrestrial planets. Hence, IOM was both the major source of Earth's volatiles and a potential source of complex prebiotic molecules. Large enrichments in D and 15N, relative to the bulk solar isotopic compositions, suggest that IOM or its precursors formed in very cold, radiation-rich environments. Whether these environments were in the interstellar medium (ISM) or the outer Solar System is unresolved. Nevertheless, the elemental and isotopic compositions and functional group chemistry of IOM provide important clues to the origin(s) of organic matter in protoplanetary disks. IOM is modified relatively easily by thermal and aqueous processes, so that it can also be used to constrain the conditions in the solar nebula prior to chondrite accretion and the conditions in the chondrite parent bodies after accretion. Here we review what is known about the abundances, compositions and physical nature of IOM in the most primitive chondrites. We also discuss how the IOM has been modified by thermal metamorphism and aqueous alteration in the chondrite parent bodies, and how these changes may be used both as petrologic indicators of the intensity of parent body processing and as tools for classification. Finally, we critically assess the various proposed mechanisms for the formation of IOM in the ISM or Solar System.

Pineapple by-product and canola oil as partial fat replacers in low-fat beef burger: Effects on oxidative stability, cholesterol content and fatty acid profile.

The effect of freeze-dried pineapple by-product and canola oil as fat replacers on the oxidative stability, cholesterol content and fatty acid profile of low-fat beef burgers was evaluated. Five treatments were performed: conventional (CN, 20% fat) and four low-fat formulations (10% fat): control (CT), pineapple by-product (PA), canola oil (CO), and pineapple by-product and canola oil (PC). Low-fat cooked burgers showed a mean cholesterol content reduction of 9.15% compared to the CN. Canola oil addition improved the fatty acid profile of the burgers, with increase in the polyunsaturated/saturated fatty acids ratio and decrease in the n-6/n-3 ratio, in the atherogenic and thrombogenic indexes. The oxidative stability of the burgers was affected by the vegetable oil addition. However, at the end of the storage time (120 days), malonaldehyde values of CO and PC were lower than the threshold for the consumer's acceptance. Canola oil, in combination with pineapple by-product, can be considered promising fat replacers in the development of healthier burgers.

Effects of pineapple byproduct and canola oil as fat replacers on physicochemical and sensory qualities of low-fat beef burger.

Pineapple byproduct and canola oil were evaluated as fat replacers on physicochemical and sensory characteristics of low-fat burgers. Five treatments were performed: conventional (CN, 20% fat) and four low-fat formulations (10% fat): control (CT), pineapple byproduct (PA), canola oil (CO), pineapple byproduct and canola oil (PC). Higher water and fat retention and lower cooking loss and diameter reduction were found in burgers with byproduct addition. In raw burgers, byproduct incorporation reduced L*, a*, and C* values, but these alterations were masked after cooking, leading to products similar to CN. Low-fat treatments were harder, chewier, and more cohesive than full-fat burgers. However, in Warner Bratzler shear measurements, PA and PC were as tender as CN. In QDA, no difference was found between CN and PC. Pineapple byproducts along with canola oil are promising fat replacers in beef burgers. In order to increase the feasibility of use of pineapple byproduct in the meat industry, alternative processes of byproduct preparation should be evaluated in future studies.

Nanoscale petrographic and geochemical insights on the origin of the Palaeoproterozoic stromatolitic phosphorites from Aravalli Supergroup, India.

Stromatolites composed of apatite occur in post-Lomagundi-Jatuli successions (late Palaeoproterozoic) and suggest the emergence of novel types of biomineralization at that time. The microscopic and nanoscopic petrology of organic matter in stromatolitic phosphorites might provide insights into the suite of diagenetic processes that formed these types of stromatolites. Correlated geochemical micro-analyses of the organic matter could also yield molecular, elemental and isotopic compositions and thus insights into the role of specific micro-organisms among these communities. Here, we report on the occurrence of nanoscopic disseminated organic matter in the Palaeoproterozoic stromatolitic phosphorite from the Aravalli Supergroup of north-west India. Organic petrography by micro-Raman and Transmission Electron Microscopy demonstrates syngeneity of the organic matter. Total organic carbon contents of these stromatolitic phosphorite columns are between 0.05 and 3.0 wt% and have a large range of δ(13) Corg values with an average of -18.5‰ (1σ = 4.5‰). δ(15) N values of decarbonated rock powders are between -1.2 and +2.7‰. These isotopic compositions point to the important role of biological N2 -fixation and CO2 -fixation by the pentose phosphate pathway consistent with a population of cyanobacteria. Microscopic spheroidal grains of apatite (MSGA) occur in association with calcite microspar in microbial mats from stromatolite columns and with chert in the core of diagenetic apatite rosettes. Organic matter extracted from the stromatolitic phosphorites contains a range of molecular functional group (e.g. carboxylic acid, alcohol, and aliphatic hydrocarbons) as well as nitrile and nitro groups as determined from C- and N-XANES spectra. The presence of organic nitrogen was independently confirmed by a CN(-) peak detected by ToF-SIMS. Nanoscale petrography and geochemistry allow for a refinement of the formation model for the accretion and phototrophic growth of stromatolites. The original microbial biomass is inferred to have been dominated by cyanobacteria, which might be an important contributor of organic matter in shallow-marine phosphorites.

Fractionated Ocimum gratissimum leaf extract inhibit prostate cancer (PC3·AR) cells growth by reducing androgen receptor and survivin levels.

In this study, the antiproliferative activity of the organic solvent-soluble and aqueous extracts of Ocimum gratissimum leaf against the prostate cancer cells PC3·AR were evaluated by their inhibitory effects on the Androgen Receptor (AR) and Survivin protein. Two organic solvent-soluble extracts P2 and P3-2, and a water- soluble extract, PS/PT1, were found to reduce AR and Survivin levels in a time-dependent manner. In addition, extract PS/PT1, also exhibited the inhibitory activity in a dose-dependent manner. This is the first time that the inhibitory eff ects of O. gratissimum extracts have been evaluated on the Androgen Receptor (AR) and Survivin protein. The results encouraged the further studies of O. gratissimum as a potential treatment of prostate cancer.

Identification of drought-responsive universal stress proteins in viridiplantae.

Genes encoding proteins that contain the universal stress protein (USP) domain are known to provide bacteria, archaea, fungi, protozoa, and plants with the ability to respond to a plethora of environmental stresses. Specifically in plants, drought tolerance is a desirable phenotype. However, limited focused and organized functional genomic datasets exist on drought-responsive plant USP genes to facilitate their characterization. The overall objective of the investigation was to identify diverse plant universal stress proteins and Expressed Sequence Tags (ESTs) responsive to water-deficit stress. We hypothesize that cross-database mining of functional annotations in protein and gene transcript bioinformatics resources would help identify candidate drought-responsive universal stress proteins and transcripts from multiple plant species. Our bioinformatics approach retrieved, mined and integrated comprehensive functional annotation data on 511 protein and 1561 ESTs sequences from 161 viridiplantae taxa. A total of 32 drought-responsive ESTs from 7 plant genera Glycine, Hordeum, Manihot, Medicago, Oryza, Pinus and Triticum were identified. Two Arabidopsis USP genes At3g62550 and At3g53990 that encode ATP-binding motif were up-regulated in a drought microarray dataset. Further, a dataset of 80 simple sequence repeats (SSRs) linked to 20 singletons and 47 transcript assembles was constructed. Integrating the datasets on SSRs and drought-responsive ESTs identified three drought-responsive ESTs from bread wheat (BE604157), soybean (BM887317) and maritime pine (BX682209). The SSR sequence types were CAG, ATA and AT respectively. The datasets from cross-database mining provide organized resources for the characterization of USP genes as useful targets for engineering plant varieties tolerant to unfavorable environmental conditions.

Potential cancer-fighting Ocimum gratissimum (OG) leaf extracts: increased anti-proliferation activity of partially purified fractions and their spectral fingerprints.

INTRODUCTION: Cancer causes about 13% of all deaths. According to the American Cancer Society, world-wide cancer deaths were 7.6 million in 2007. African Americans and other minorities are disproportionately affected. Effective cancer chemotherapy is scarce. This study is part of an ongoing search for potential cancer-fighting agents in medicinal herbs. In previous in-vitro studies, we have shown that the aqueous extracts of the medicinal herb Ocimum gratissimum (Og) inhibit the proliferation of several cancer cell lines, especially prostate adenocarcinoma (PC-3) cells. Therefore, Og leaf extracts may harbor novel cancer-fighting compounds that need to be isolated, purified and characterized. METHODS: Partially purified Og fractions were obtained from sequential extraction of Og powder with organic solvents of different polarities. The hypothesis that the anti-proliferation activity of the fractions will be significantly greater than that of either aqueous or ethanol extracts was tested by treating PC-3 cells with 1.61 mg/mL of each fraction. Spectral analysis of the fractions was also conducted. RESULTS: Activity of the fractions was P2>P(3-2)>P(4-2)>P(3-1)>P(4-1). Fractions P2, P(3-2) and P(4-2) were 725, 75 and 2.3 times more active than the aqueous extract, respectively. Spectral analysis revealed peaks for: P(3-2) and aqueous extract at 208 nm, P2 and P(4-2) at 210 nm, and P(3-1) at 220 nm. CONCLUSIONS: These findings suggest that fractions P2, P(3-2) and P(4-2) could be potential sources of Og's bioactive component(s) that warrant further purification and characterization.

Virtual surgical telesimulations in otolaryngology.

Distance learning can be enhanced with the use of virtual reality; this paper describes the design and initial validation of a Web Environment for Surgery Skills Training on Otolaryngology (WESST-OT). WESST-OT was created aimed to help trainees to gain the skills required in order to perform the Functional Endoscopic Sinus Surgery procedure (FESS), since training centers and specialist in this knowledge are scarce in Colombia; also, it is part of a web based educational cycle which simulates the stages of a real procedure. WESST-OT is one from the WESST family of telesimulators which started to be developed from an architecture proposed at the Medicine Meets Virtual Reality conference 2002; also, it is a step towards the use of virtual reality technologies in Latin America.

Morphological and physiological responses of morning glory (Ipomoea lacunosa L.) grown in a lead- and chelate-amended soil.

Lead (Pb) is one of the most toxic metals in the environment and may cause drastic morphological and physiological deformities in Ipomoea lacunosa. The goal of this research was to evaluate some morphological and physiological responses of morning glory grown on a Pb- and chelate-amended soil. Soil samples were analyzed, at Mississippi State University Soil Laboratory, for physico-chemical parameters, such as soil texture (73% sand, 23% silt, 4.4% clay), organic matter (6.24 +/- 0.60%), and pH (7.95 +/- 0.03), to establish soil conditions at the beginning of the experiments. Five EDTA (ethylenediaminetetraacetic acid) concentrations (0, 0.1, 0.5, 1, 5mM) and four lead (0, 500, 1000, 2000mg/L) treatments were arranged in factorial in a Randomized Complete Block (RCB) design with five replications. Duncan's multiple comparison range test showed that the mean difference values of stomatal density were significant between 500 and 1000mg/L Pb and between 1000 and 2000mg/L Pb. Two way ANOVA (at 1% level) indicated that interaction between Pb and EDTA had a significant effect on the stomatal density and photosynthetic rates, and at 5% level Pb had a significant effect on chlorophyll concentrations. Lowest concentrations of chlorophyll were recorded at 2000mg/L Pb and 5mM EDTA and exhibited a decreasing trend specifically in the ranges of 1000 and 2000mg/L Pb and 1.0 and 5.0mM EDTA. Duncan's multiple comparison range test confirmed that mean differences between the control treatment vs. 2000mg/L Pb, and 500mg/L vs. 2000mg/L Pb were significantly different atp>0.05. There was a decrease in leaf net photosynthetic rate with increasing concentrations of Pb from 0 to 2000mg/L. In conclusion, I. lacunosa L. plants were grown to maturity in all treatments with no significant and/or apparent morphological disorders, which indicated that this species might be highly tolerant even at 2000mg/L Pb concentrations in the soil.

Noninvasive diagnosis of gastroesophageal inflammation using dipyridamole thallium-201 tomography.

OBJECTIVE: Esophagitis, a complication of GERD, and gastric erosions are common findings in dyspeptic patients. Unfortunately, these findings cannot be predicted based on symptoms alone and require endoscopy for an accurate diagnosis. Noninvasive diagnosis of other gastrointestinal pathology by radiopharmaceuticals (GA 67, Tc 99m pertechnetate) has previously been studied. We hypothesized that endoscopically documented esophagitis and/or gastric erosions could also be detected by using dipyridamole thallium-201 imaging and, if they were of sufficient accuracy, could serve as a useful, noninvasive screening test for esophagitis and/or gastric erosions. METHODS: A pilot study was undertaken in 12 patients undergoing endoscopy for symptoms of GERD or dyspepsia. Esophagitis was defined as the presence of either erosions or ulceration and gastric erosions were defined as discrete mucosal breaks measuring > or = 1 mm. Dipyridamole thallium-201 imaging was performed the following day on all 12 patients. A standard dose of dipyridamole (0.56 mg/kg) was infused over 4 min, followed by a 3-mCi dose of thallium-201. Initial stress tomographic images and reinjection (1 mCi) resting tomographic images 3-4 h later were obtained using a gamma camera. Tomographic images were read blinded to the endoscopy results. Thallium-201 uptake was graded on a 0-3+ scale using the liver uptake as the internal comparative standard (2+ = uptake equal to the liver). Abnormal thallium uptake was defined as > or = 2+ in the area of the esophagus or stomach. RESULTS: Seven women and five men (mean age 41 yr, range 25-60 yr) were studied. Eight patients were taking histamine-2 receptor antagonists and none were on proton pump inhibitors, or promotility agents. All five patients with endoscopic esophagitis had a positive thallium-201 tomographic image. Seven patients had no evidence of esophagitis, and three had positive thallium-201 tomograms. Dipyridamole thallium-201 imaging sensitivity, specificity, and positive and negative predictive values for esophagitis were 100%, 57%, 63%, and 100%, respectively. All three patients with gastric erosions had positive thallium-201 tomograms. Six of nine patients without gastric erosions had positive tomograms. The sensitivity, specificity, and positive and negative predictive values of DT 201 gastric erosions were 100%, 33%, 33%, and 100%, respectively. CONCLUSIONS: Dipyridamole thallium-201 tomographic imaging has good sensitivity (100%) in detecting esophagogastric mucosal erosions, but its poor specificity (33-57%) results in an unacceptable accuracy as a screening test. Additionally, the cost of radiopharmaceuticals requires that sensitivity and specificity be at least equal to that of endoscopy for this test to be clinically valuable as a screening test. However, a noninvasive test for these diseases is inherently appealing, and further research in this area seems to be warranted.

Treatment of esophageal obstruction from mediastinal compressive tumor with covered, self-expanding metallic Z-stents.

BACKGROUND: Mediastinal malignancies may involve the esophagus, leading to esophageal stenosis and dysphagia. Rigid and self-expanding esophageal stents have been used for effective palliation, but their use in extrinsic, compressive lesions is controversial. METHODS: A retrospective review of self-expanding Gianturco-Rösch Z-stents that were successfully placed in 13 patients with malignant esophageal obstruction due to extrinsic lesions. RESULTS: All patients had an improvement in dysphagia of at least two dysphagia grades. The mean dysphagia grade fell from 3.15 to 0.62. Mean survival was 2.2 months. Early (within 48 hours) procedure-related complications occurred in 4 of 13 patients and consisted of minor, transient chest pain that resolved within 6 hours (3 patients) and endoscopic stent dislodgment into the stomach (1 patient). Late complications (> 48 hours) occurred in 2 patients and consisted of a partial proximal stent migration and the development of a benign stricture proximal to the stent. There was no procedural or stent related mortality. CONCLUSIONS: Esophageal obstruction and malignant dysphagia from extrinsic, compressive mediastinal malignancies can be effectively and safely palliated with self-expanding Gianturco- Rösch Z-stents.