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1.
Pediatr Blood Cancer ; 71(4): e30880, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38291716

RESUMEN

BACKGROUND: The primary objective was to measure the proportion of episodes where care delivery was inconsistent with selected recommendations of a clinical practice guideline (CPG) on fever and neutropenia (FN) management. The influence of site size on CPG-inconsistent care delivery, and association between patient outcomes and CPG-inconsistent care were described. METHODS: This retrospective, multicenter study included patients less than 21 years old with cancer who were at high risk of poor FN outcomes and were previously enrolled to a Children's Oncology Group (COG) study at participating National Cancer Institute Community Oncology Research Program (NCORP) institutions from January 2014 through December 2015. Patients were randomly selected for chart review by participating sites from a COG-generated list. Care delivered in each episode was adjudicated (CPG-consistent or CPG-inconsistent) against each of five selected recommendations. RESULTS: A total of 107 patients from 22 sites, representing 157 FN episodes, were included. The most common CPG-inconsistent care delivered was omission of pulmonary computerized tomography in patients with persistent FN (60.3%). Of 74 episodes where assessment of four (episodes without persistent FN) or five (episodes with persistent FN) recommendations was possible, CPG-inconsistent care was delivered with respect to at least one recommendation in 63 (85%) episodes. Site size was not associated with CPG-inconsistent care delivery. No statistically significant association between CPG-inconsistent care and fever recurrence was observed. CONCLUSIONS: In this cohort of pediatric patients at high risk of poor FN outcomes, CPG-inconsistent care was common. Opportunities to optimize resource stewardship by boosting supportive care CPG implementation are highlighted.


Asunto(s)
Fiebre de Origen Desconocido , Neoplasias , Neutropenia , Niño , Humanos , Adulto Joven , Oncología Médica , Neoplasias/complicaciones , Neoplasias/terapia , Neutropenia/terapia , Neutropenia/complicaciones , Estudios Retrospectivos , Adolescente
2.
Genetica ; 151(2): 119-131, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36717534

RESUMEN

Nucleotide Binding Site - Leucine Rich Repeat (NBS-LRR) genes play a significant role in plant defense against biotic stresses and are an integral part of signal transduction pathways. Vat gene has been well reported for their role in resistance to Aphis gossypii and viruses transmitted by them. Despite their importance, Vat like NBS-LRR resistance genes have not yet been identified and studied in cotton species. This study report hundreds of orthologous Vat like NBS-LRR genes from the genomes of 18 cotton species through homology searches and the distribution of those identified genes were tend to be clustered on different chromosome. Especially, in a majority of the cases, Vat like genes were located on chromosome number 13 and they all shared two conserved NBS-LRR domains, one disease resistant domain and several repeats of LRR on the investigated cotton Vat like proteins. Gene ontology study on Vat like NBS-LRR genes revealed the molecular functions viz., ADP and protein binding. Phylogenetic analysis also revealed that Vat like sequences of two diploid species, viz., G. arboreum and G. anomalum, were closely related to the sequences of the tetraploids than all other diploids. The Vat like genes of G. aridum and G. schwendimanii were distantly related among diploids and tetraploids species. Various hormones and defense related cis-acting regulatory elements were identified from the 2 kb upstream sequences of the Vat like genes implying their defensive response towards the biotic stresses. Interestingly, G. arboreum and G. trilobum were found to have more regulatory elements than larger genomes of tetraploid cotton species. Thus, the present study provides the evidence for the evolution of Vat like genes in defense mechanisms against aphids infestation in cotton genomes and allows further characterization of candidate genes for developing aphid and aphid transmitted viruses resistant crops through cotton breeding.


Asunto(s)
Áfidos , Animales , Áfidos/genética , Áfidos/metabolismo , Nucleótidos/metabolismo , Filogenia , Tetraploidía , Fitomejoramiento , Sitios de Unión/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Resistencia a la Enfermedad/genética
3.
Langmuir ; 37(5): 1788-1798, 2021 02 09.
Artículo en Inglés | MEDLINE | ID: mdl-33497235

RESUMEN

A series of amphiphilic double-brush polymers based on itaconate diesters were synthesized with the objective of tailoring the thermal and mechanical properties of hydrogels formed by them; the amphiphilic itaconate diesters carried an MPEG350 segment and an alkyl chain, whose length was varied from C12 to C18. As was reported by us earlier (Macromolecules 2017, 50, 5004), the formation of the hydrogel was due to the crystallization of alkyl segments, as confirmed by the match of the rheological gel-to-sol transition with that of differential scanning calorimetry melting transition of the gel. In an effort to fine-tune the hydrogel-melting temperature and its strength, we varied the length of the alkyl chain length while keeping the hydrophilic segment length constant at MPEG350; apart from varying the alkyl chain length, an oxyethylene spacer was incorporated to examine the effect of decoupling the alkyl side-chain crystallization from the backbone. With these modifications, the melting temperature of the hydrogel was varied from 30 to 56 °C. Likewise, the strength of the hydrogel, as reflected by its storage modulus, varied from around 220 to 970 Pa; the softer gels typically exhibited a slightly larger critical shear strain beyond which the gel transformed into a sol. The thermal and shear-induced gel-to-sol transitions were reversible; however, the modulus after the shear-induced transition did not fully recover instantly (∼80%), suggesting that the formation of the extended gel network is slow. Further fine-tuning could be achieved by copolymerization of two different amphiphilic itaconate monomers, namely, those with C16 and C18, which provided an intermediate gel-melting temperature; however, co-gelation of the two preformed homopolymer gels yielded two distinct gel-melting transitions. Thus, this class of tuneable stimuli-responsive polymeric hydrogels prepared from biobenign components, namely, itaconic acid, 1-alkanols, and MPEGs, could serve as potential candidates for biomedical applications.

4.
Langmuir ; 37(42): 12457-12465, 2021 10 26.
Artículo en Inglés | MEDLINE | ID: mdl-34641685

RESUMEN

Periodically grafted amphiphilic copolymers (PGACs) were earlier shown by us to adopt a zigzag folded conformation in the solid state, which enabled the backbone and pendant segments to segregate and occupy alternate layers in a lamellar structure. The conformational transition from a random coil to a zigzag folded chain in solution is an interesting problem, which is largely unexplored. To examine this, an orthogonally clickable parent polyester was sequentially clicked with two types of poly(ethylene glycol) (PEG) segments: one is a simple PEG and the other is a PEG that carries a dipolar chromophore. These two hydrophilic PEG segments, installed in a periodic and alternating fashion along the hydrocarbon-rich (HC) polyester backbone, ensure that the Janus folded chains are formed upon folding and carry chromophoric dipoles oriented along the same direction, thereby generating a large net dipole. The folding-induced alignment of chromophores in solution was followed using second harmonic light scattering (SHLS), wherein the intensity of the frequency-doubled scattered light (I2ω) is measured. Folding was induced by adding a polar solvent, like methanol, to a chloroform solution of the polymer; methanol desolvates the HC backbone but solubilizes the pendant PEG segments, thus inducing folding. The second harmonic intensity (I2ω) increased initially with methanol concentration and then saturated; in contrast, I2ω remained invariant with the solvent composition in the case of an analogous model chromophore. Furthermore, in a model PGAC carrying chromophore-bearing PEG segments on every repeat unit, I2ω decreased with increasing methanol composition, revealing the formation of a centrosymmetric folded chain, wherein the chromophoric dipoles on either side cancel each other. Thus, this study clearly reveals that the zigzag chain folding of PGACs can be induced by a segment-selective solvent, resulting in the rather elusive directional ordering of chromophoric dipoles in solution.


Asunto(s)
Polímeros , Microscopía de Generación del Segundo Armónico , Interacciones Hidrofóbicas e Hidrofílicas , Polietilenglicoles , Solventes
5.
J Nanosci Nanotechnol ; 19(4): 2158-2165, 2019 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-30486960

RESUMEN

In this present study, a highly conductive thermally reduced graphene oxide (TRGO) was synthesized by a low temperature thermal reduction method using RF heating, under an argon-hydrogen atmosphere. The crystallinity and morphology were examined by X-ray diffraction, Raman spectroscopy and TEM analysis. The chemical structure including the functional groups present on TRGO was studied using X-ray photoelectron spectroscopy and FTIR analysis. The studies reveal that thermal reduction of graphene oxide was successful under the experimental conditions and that the TRGO had high crystallinity. Further, the performance of the as-prepared TRGO was tested as a counter electrode (CE) in a dye-sensitized solar cell (DSSC). The maximum power conversion efficiency (PCE) obtained was 4.86% for TRGO under one sun illumination, which is comparable to that of a platinum CE-based DSSC (5.24%). The electrocatalytic activity and electron transfer kinetics were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Tafel measurements. The series resistance (Rs) and charge transfer resistance (Rct) values were found to be 35.4 Ωcm-2 and 56.40 Ωcm-2 for TRGO. The results reveal that the TRGO had an electrocatalytic performance similar to that of Pt, making TRGO-CEs promising alternatives to the conventional Pt-CEs in DSSCs.

6.
Int J Obes (Lond) ; 42(4): 939-945, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29359735

RESUMEN

BACKGROUND/OBJECTIVES: Thermogenic fat is present in humans and emerging evidence indicates that increasing the content and activity of these adipocytes may lead to weight loss and improved metabolic health. Multiple reporter systems have been developed to assay thermogenic fat activity based on the transcriptional and translational activation of Ucp1, the key molecule that mediates nonshivering thermogenesis. Our study aims to develop a much-needed tool to monitor thermogenic fat activity through a mechanism independent of Ucp1 regulation, therefore effectively assaying not only canonical ß-adrenergic activation but also various non-UCP1-mediated thermogenic pathways that have been increasingly appreciated. METHODS: We detected increased luciferase activity upon thermogenic activation in interscapular brown and inguinal subcutaneous fat in ODD-Luc mice, a hypoxia reporter mouse model. We then developed an OLTAM (ODD-Luc based Thermogenic Activity Measurement) system to assay thermogenic fat cell activity. RESULTS: In both primary murine and human adipocytes and an immortalized adipose cell line that were transduced with the OLTAM system, luciferase activity can be readily measured and visualized by bioluminescence imaging in response to a variety of stimuli, including UCP1-independent thermogenic signaling. This system can offer a convenient method to assay thermogenic activity for both basic and translational research. CONCLUSIONS: The OLTAM system offers a convenient way to measure the activation of thermogenic fat and presents opportunities to discover novel signaling pathways and unknown compounds targeting metabolically active adipocytes to counteract human obesity.


Asunto(s)
Tejido Adiposo Beige/fisiología , Tejido Adiposo Pardo/fisiología , Termogénesis/fisiología , Termografía/métodos , Adipocitos/citología , Tejido Adiposo Beige/química , Tejido Adiposo Pardo/química , Adulto , Animales , Células Cultivadas , Femenino , Genes Reporteros , Humanos , Luciferasas/análisis , Luciferasas/metabolismo , Ratones , Monitoreo Fisiológico , Adulto Joven
7.
Langmuir ; 34(39): 11729-11737, 2018 10 02.
Artículo en Inglés | MEDLINE | ID: mdl-30193459

RESUMEN

Itaconic acid was readily transformed to a series of amphiphilic diesters via stepwise esterification of itaconic anhydride; the diesters carry one alkyl (cetyl or octyl) group and either a PEG, glyceryl, or dopamine segment. These diesters were used as surfmers for the preparation of polystyrene (PS) emulsions, with the expectation that the surface of the emulsion particles would carry PEG, glyceryl or dopamine units. NMR spectroscopic studies revealed that the surfmers were covalently incorporated into the polystyrene chains; furthermore, NMR tube polymerization experiments also confirmed that when the PEG surfmer was used, the PEG segments are indeed present on the surface of the emulsion particles. The size of the PEGlyated PS emulsions was readily varied from 35 to 140 nm by changing the mole fraction of surfmer used. In the case of the glyceryl and dopamine carrying surfmers, an octyl unit was used as the hydrophobic segment to ensure appropriate hydrophobic-hydrophilic balance; it was noticed that significantly larger mole fractions of the surfmers were required (15-20 mol %) to generate stable emulsions with particle sizes of about 150 nm. The PS emulsions carrying dopamine units on the surface were found to adhere to glass surfaces; thus suggesting that such "sticky" emulsion particles could be used to functionalize different types of surfaces. Finally, itaconate diesters bearing cetyl and perfluorooctyl segments were also prepared and shown to copolymerize with styrene to generate fluoroalkyl-enriched PS copolymers; these were used to generate hydrophobic coatings, with water contact angles of over 120°. Thus, itaconate-based surfmers are readily accessible alternatives for the preparation of emulsions with tailored size and surface functionality.

8.
Langmuir ; 34(38): 11464-11472, 2018 09 25.
Artículo en Inglés | MEDLINE | ID: mdl-30156421

RESUMEN

A hyperbranched (HB) polyester carrying peripheral allyl groups was prepared by melt-condensation of a suitably designed AB2 monomer bearing two allyl ester groups and one hydroxyl group. The periphery of the hyperbranched polymer was co-clicked with two different organic thiols, namely, hexadecane thiol and 3-mercaptopropionic acid, using the thiol-ene reaction. Three different samples with varying mole fractions of the hydrophilic carboxylic acid groups were prepared; the conformational adaptability of the hyperbranched polymer backbone permitted these amphiphilic systems to form Janus structures that exhibit surfactant-like properties and, therefore, we have termed them hybrasurfs. These polymers behave like clusters of surfactants that have been stitched at the waist by the HB polymer backbone; the Langmuir isotherms revealed the formation of a monolayer, and in two of the samples having higher mole fractions of hexadecyl segments a weak inflection in the isotherm is seen. This suggests a densification, typically implying the crystallization of the alkyl segment at the air-water interface. The monolayers were transferred onto a substrate, and their heights were estimated using atomic force microscopy; the values thus obtained were in reasonable agreement with the expected value. The water contact angles of the substrates bearing the transferred monolayers of the three different samples (transferred at two different points along the isotherm) were measured; it was seen that the sample carrying the highest mole fraction of hexadecyl chains exhibited a significantly larger contact angle when compared to that of the other two samples. Interestingly, these hybrasurfs also formed vesicles in water and were shown to encapsulate water-soluble dyes, such as Eosin Y. Thus, this class of readily accessible amphiphilic HB polymers that behave as a cluster of surfactants opens some interesting possibilities for further exploration.

10.
J Nanosci Nanotechnol ; 18(2): 1089-1096, 2018 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-29448538

RESUMEN

Bilayer and few layer-graphene (Gr) with noble metal (Ag and Au) and TiO2 nanoparticles were synthesized using atmospheric pressure radio frequency chemical vapor deposition (APRF-CVD). The precursors for the formation of the respective nanoparticles were dissolved in ethanol and injected into the APRF-CVD containing a Cu foil catalyst at 1000 °C. The graphene obtained had a blistered morphology similar to bubble-wrap. The bubble-like protrusions on the graphene sheet were caused by large nanoparticle clusters (~220 nm) formed below the graphene sheets. Smaller nanoparticles (10-80 nm) were also observed on top of the graphene sheets. Encapsulation of the nanoparticles with graphene, to yield core-shell particles was observed. Similarly, secondary growth of carbon nanotubes (CNTs) from the Au nanoparticles was observed. The average full width half maxima (FWHM) of 2D bands in the Raman spectra indicate that the graphene formed was predominantly bilayer graphene for Gr-TiO2 (55 ± 1.72 cm-1), and few-layer graphene for Gr-Ag (76 ± 22 cm-1) and Gr-Au (88 ± 4.7 cm-1). Raman spectroscopy also showed evidence for the doping of graphene and surface-enhanced Raman sensitivity (SERS) in the materials. These electronic properties of graphene with nanoparticles are relevant to various applications such as optoelectronics, catalysis, chemical and biological sensing.

11.
Rep Prog Phys ; 80(11): 116501, 2017 11.
Artículo en Inglés | MEDLINE | ID: mdl-28675142

RESUMEN

Rare earth compounds of the type [Formula: see text] (R = rare earth; T = Rh, Ir, and X = Si, Ge, Sn) display a variety of phase transitions towards exotic states, including charge density waves (CDW), local moment magnetism, antiferromagnetism in the heavy fermion state, superconductivity and giant positive magnetoresistance. They support strongly correlated electron systems. In particular, R 5Ir4 [Formula: see text] (R = Dy-Lu) exhibit strong coupling CDWs with high transition temperatures, and superconductivity or magnetic ordering at lower temperatures. [Formula: see text] [Formula: see text] (R = Gd-Tm; T = Co, Rh, Ir) show multiple magnetic transitions with large magnetoresistance below the magnetic transitions. Finally, the light rare earth series [Formula: see text] [Formula: see text] (R = Ce, Pr, Nd; T = Rh, Ir) display heavy fermion behaviour (for Ce and Pr) or possess giant positive magnetoresistance (for Nd) at low temperatures. This review provides a comprehensive overview of compounds, crystal structures and phase transitions. This is followed by an in-depth discussion of the mechanisms of the phase transitions and the properties of the ordered states.

12.
J Med Syst ; 40(1): 25, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26547845

RESUMEN

Automated analysis and differentiation of mild cognitive impairment and Alzheimer's condition using MR images is clinically significant in dementic disorder. Alzheimer's Disease (AD) is a fatal and common form of dementia that progressively affects the patients. Shape descriptors could better differentiate the morphological alterations of brain structures and aid in the development of prospective disease modifying therapies. Ventricle enlargement is considered as a significant biomarker in the AD diagnosis. In this work, a method has been proposed to differentiate MCI from the healthy normal and AD subjects using Laplace-Beltrami (LB) eigen value shape descriptors. Prior to this, Reaction Diffusion (RD) level set is used to segment the ventricles in MR images and the results are validated against the Ground Truth (GT). LB eigen values are infinite series of spectrum that describes the intrinsic geometry of objects. Most significant LB shape descriptors are identified and their performance is analysed using linear Support Vector Machine (SVM) classifier. Results show that, the RD level set is able to segment the ventricles. The segmented ventricles are found to have high correlation with GT. The eigen values in the LB spectrum could show distinction in the feature space better than the geometric features. High accuracy is observed in the classification results of linear SVM. The proposed automated system is able to distinctly separate the MCI from normal and AD subjects. Thus this pipeline of work seems to be clinically significant in the automated analysis of dementic subjects.


Asunto(s)
Enfermedad de Alzheimer/diagnóstico , Encéfalo/fisiopatología , Disfunción Cognitiva/diagnóstico , Interpretación de Imagen Asistida por Computador/métodos , Anciano , Anciano de 80 o más Años , Biomarcadores , Diagnóstico Diferencial , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Reproducibilidad de los Resultados , Máquina de Vectores de Soporte
13.
J Med Syst ; 40(1): 28, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26547848

RESUMEN

Analysis of neuromuscular fatigue finds various applications ranging from clinical studies to biomechanics. Surface electromyography (sEMG) signals are widely used for these studies due to its non-invasiveness. During cyclic dynamic contractions, these signals are nonstationary and cyclostationary. In recent years, several nonstationary methods have been employed for the muscle fatigue analysis. However, cyclostationary based approach is not well established for the assessment of muscle fatigue. In this work, cyclostationarity associated with the biceps brachii muscle fatigue progression is analyzed using sEMG signals and Spectral Correlation Density (SCD) functions. Signals are recorded from fifty healthy adult volunteers during dynamic contractions under a prescribed protocol. These signals are preprocessed and are divided into three segments, namely, non-fatigue, first muscle discomfort and fatigue zones. Then SCD is estimated using fast Fourier transform accumulation method. Further, Cyclic Frequency Spectral Density (CFSD) is calculated from the SCD spectrum. Two features, namely, cyclic frequency spectral area (CFSA) and cyclic frequency spectral entropy (CFSE) are proposed to study the progression of muscle fatigue. Additionally, degree of cyclostationarity (DCS) is computed to quantify the amount of cyclostationarity present in the signals. Results show that there is a progressive increase in cyclostationary during the progression of muscle fatigue. CFSA shows an increasing trend in muscle fatiguing contraction. However, CFSE shows a decreasing trend. It is observed that when the muscle progresses from non-fatigue to fatigue condition, the mean DCS of fifty subjects increases from 0.016 to 0.99. All the extracted features found to be distinct and statistically significant in the three zones of muscle contraction (p < 0.05). It appears that these SCD features could be useful in the automated analysis of sEMG signals for different neuromuscular conditions.


Asunto(s)
Electromiografía/métodos , Análisis de Fourier , Fatiga Muscular/fisiología , Músculo Esquelético/fisiología , Adulto , Humanos
14.
J Food Sci Technol ; 53(6): 2851-62, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-27478242

RESUMEN

Among several traditional foods of India, idli is one of the most popular and commonly consumed steamed products. A new method of adding Murraya koenigii (curry leaves) to idli batter as a vehicle for fortification and extension of shelf-life has been developed. Dried curry leaves powder was incorporated with other ingredients like rice and dehusked black gram in different proportions to optimize the most palatable formulation. Rate of fermentation and microbial changes in the batter; nutritional qualities, texture and sensory properties of the prepared product were assessed. Incorporation of curry leaves powder (5 %) in idli batter increased the shelf-life and also increased the flavour, texture and appearance of the idli. The calcium content of the prepared idli was 10 times more than that of the control idli, while dietary fiber content increased by 18.6 %. Anti-microbial activity of the curry leaves in idli batter extended the shelf-life from 2 to 5 days when stored at 30 °C.

15.
Langmuir ; 31(22): 6035-44, 2015 Jun 09.
Artículo en Inglés | MEDLINE | ID: mdl-25984651

RESUMEN

Two series of periodically clickable polyesters were prepared; one of them carries alkylene segments along its backbone, whereas the other carries poly(ethylene glycol) (PEG) segments. These polyesters were clicked with either MPEG-350 azide or docosyl (C22) azide to yield periodically grafted amphiphilic copolymers (PGACs) carrying either flexible hydrophilic or crystallizable hydrophobic backbone segments. The immiscibility between hydrocarbon and PEG segments causes both of these systems to fold in either a zigzag or hairpin-like conformation; the hairpin-like conformation appears to be preferred when flexible PEG segments are present in the backbone. The folded chains further reorganize in the solid state to develop a lamellar morphology that permits the collocation of the PEG and hydrocarbon (HC) segments within alternate domains; evidence for the self-segregation was gained from DSC, SAXS, and AFM studies. SAXS studies revealed the formation of an extended lamellar structure, whereas AFM images showed uniform layered morphology with layer heights that matched reasonably well with the interlamellar spacing obtained from the SAXS study. Labeling one representative PGAC, carrying crystallizable long alkylene segments in the backbone and pendant PEG-350 side chains, with a small mole fraction of pyrene fluorophore permitted the examination of the conformational transition that occurs upon going from a good to a poor solvent; this single-chain folded conformation, we postulate, is the intermediate that organizes into the lamellar morphology.

16.
J Nanosci Nanotechnol ; 15(7): 5042-7, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-26373074

RESUMEN

This work reports a graphene-based nonenzymatic electrochemical sensing platform for the detection of dopamine (DA), uric acid (UA), and ascorbic acid (AA). Graphene oxide, synthesized by modified Hummers method, was thermally reduced in an induction furnace at 200 °C in an Ar-H2 atmosphere to obtain thermally reduced graphene oxide (tRGO). Nanocomposites of tRGO-TiO2 were obtained by a hydrothermal method, and were characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD). FTIR spectra showed Ti-O-C peaks, indicating covalent linkage between the TiO2 nanoparticles and the reduced graphene oxide sheets. Glassy carbon electrode (GCE) was modified with the nanocomposite (tRGO-TiO2-GCE), and the modified electrode could detect dopamine (DA: 1 to 1000 µM), uric acid (UA: 1 to 900 µM), and ascorbic acid (AA: 10 to 1000 µM) in each other's presence over wide ranges, with adequate separation in peak potentials. Differential pulse voltammetry experiments yielded linear responses with sensitivities of 133.18, 33.96, and 155.59 µA mM(-1) cm(-2) for DA, UA, and AA, respectively.


Asunto(s)
Ácido Ascórbico/análisis , Dopamina/análisis , Técnicas Electroquímicas , Grafito/química , Nanocompuestos/química , Titanio/química , Ácido Úrico/análisis
17.
J Am Chem Soc ; 136(6): 2538-45, 2014 Feb 12.
Artículo en Inglés | MEDLINE | ID: mdl-24432739

RESUMEN

A series of polyesters based on 2-propargyl-1,3-propanediol or 2,2-dipropargyl-1,3-propanediol or 2-allyl-2-propargyl-1,3-propanediol and 1,20-eicosanedioic acid were prepared by solution polycondensation using the corresponding diacid chloride; these polyesters were quantitatively "clicked" with a fluoroalkyl azide, namely CF3(CF2)7CH2CH2N3, to yield polyesters carrying long-chain alkylene segments in the backbone and either one or two perfluoroalkyl segments located at periodic intervals along the polymer chain. The immiscibility of the alkylene and fluoroalkyl segments causes the polymer chains to fold in a zigzag fashion to facilitate the segregation of these segments; the folded chains further organize in the solid state to form a lamellar structure with alternating domains of alkyl (HC) and fluoroalkyl (FC) segments. Evidence for the self-segregation is provided by DSC, SAXS, WAXS, and TEM studies; in two of the samples, the DSC thermograms showed two distinct endotherms associated with the melting of the individual domains, while the WAXS patterns confirm the existence of two separate peaks corresponding to the interchain distances within the crystalline lattices of the HC and FC domains. SAXS data, on the other hand, reveal the formation of an extended lamellar morphology with an interlamellar spacing that matches reasonably well with those estimated from TEM studies. Interestingly, a smectic-type liquid crystalline phase is observed at temperatures between the two melting transitions. These systems present a unique opportunity to develop interesting nanostructured polymeric materials with precise control over both the domain size and morphology; importantly, the domain sizes are far smaller than those typically observed in traditional block copolymers.

18.
J Nanosci Nanotechnol ; 14(7): 5011-8, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24757974

RESUMEN

Nanofiber composites (Polyimide/f-SWCNT) of Pyromellitic dianhydride, 4,4'-Oxydianiline, and 4,4'-(4,4'-isopropylidene diphenyl-1,1'-diyl dioxy) dianiline (PMDA-ODA/IDDA) and surface-functionalized single walled carbon nanotubes (f-SWCNT) were made by electrospinning a solution of poly(amic acid) (PAA) containing 0-2 wt% f-SWCNT followed by thermal imidization. X-ray photoelectron spectroscopy spectra verified the oxidation of SWCNT surface after acid treatment, and indicated possible hydrogen bonding interactions between the f-SWCNTs and polyamic acid. High-resolution scanning electron microscopy images showed the average diameter of nanofibers to be below 150 nm, and transmission electron microscopy images showed that SWCNTs were aligned inside the polymer nanofiber. In thermogravimetric analysis, all composites showed increased thermal stability with increasing f-SWCNT content compared to neat PI. Storage modulus also increased from 124 MPa to 229 MPa from neat PI to 2% f-SWCNT composite.

19.
J Med Syst ; 38(9): 101, 2014 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-25064085

RESUMEN

In this study, an attempt is made to distinguish the normal and abnormal tissues in breast thermal images using Gabor wavelet transform. Thermograms having normal, benign and malignant tissues are considered in this study and are obtained from public online database. Segmentation of breast tissues is performed by multiplying raw image and ground truth mask. Left and right breast regions are separated after removing the non-breast regions from the segmented image. Based on the pathological conditions, the separated breast regions are grouped as normal and abnormal tissues. Gabor features such as energy and amplitude in different scales and orientations are extracted. Anisotropy and orientation measures are calculated from the extracted features and analyzed. A distinctive variation is observed among different orientations of the extracted features. It is found that the anisotropy measure is capable of differentiating the structural changes due to varied metabolic conditions. Further, the Gabor features also showed relative variations among different pathological conditions. It appears that these features can be used efficiently to identify normal and abnormal tissues and hence, improve the relevance of breast thermography in early detection of breast cancer and content based image retrieval.


Asunto(s)
Neoplasias de la Mama/diagnóstico , Interpretación de Imagen Asistida por Computador/métodos , Termografía/métodos , Análisis de Ondículas , Algoritmos , Anisotropía , Mama/patología , Femenino , Humanos
20.
J Med Syst ; 38(10): 132, 2014 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-25187409

RESUMEN

ECG Steganography provides secured transmission of secret information such as patient personal information through ECG signals. This paper proposes an approach that uses discrete wavelet transform to decompose signals and singular value decomposition (SVD) to embed the secret information into the decomposed ECG signal. The novelty of the proposed method is to embed the watermark using SVD into the two dimensional (2D) ECG image. The embedding of secret information in a selected sub band of the decomposed ECG is achieved by replacing the singular values of the decomposed cover image by the singular values of the secret data. The performance assessment of the proposed approach allows understanding the suitable sub-band to hide secret data and the signal degradation that will affect diagnosability. Performance is measured using metrics like Kullback-Leibler divergence (KL), percentage residual difference (PRD), peak signal to noise ratio (PSNR) and bit error rate (BER). A dynamic location selection approach for embedding the singular values is also discussed. The proposed approach is demonstrated on a MIT-BIH database and the observations validate that HH is the ideal sub-band to hide data. It is also observed that the signal degradation (less than 0.6%) is very less in the proposed approach even with the secret data being as large as the sub band size. So, it does not affect the diagnosability and is reliable to transmit patient information.


Asunto(s)
Seguridad Computacional , Electrocardiografía/métodos , Difusión de la Información , Análisis de Ondículas , Algoritmos , Confidencialidad , Humanos , Procesamiento de Señales Asistido por Computador , Relación Señal-Ruido
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