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1.
J Agric Food Chem ; 71(46): 17752-17762, 2023 Nov 22.
Artículo en Inglés | MEDLINE | ID: mdl-37943715

RESUMEN

Natural products are a crucial source in the development of new eco-friendly antiviral agents to control plant viral diseases. In our previous studies, some ferulic acid derivatives with good antiviral activity were obtained as an immune activator. To continue the discovery of eco-friendly antiviral agents, different monosaccharides were introduced into cinnamic acid skeletons by an activity-based strategy to obtain a series of cinnamic acid derivatives containing glycoside scaffolds, and their antiviral activities against tobacco mosaic virus (TMV) and tomato spotted wilt virus (TSWV) were evaluated. Among them, compound 8d showed the greatest protective activities against TMV and TSWV, with the EC50 values of 128.5 and 236.8 µg mL-1, respectively, which were superior to those of ningnanmycin (238.5 and 315.7 µg mL-1, respectively). Moreover, compound 8d could significantly improve the defense enzyme activities of peroxidase, chitinase, and ß-1,3-glucanase. Proteomic and transcriptome analyses indicated that compound 8d regulated gene transcription and protein expression levels involved in the defense response to resist virus infection. The present study revealed that compound 8d is a potential lead candidate for the development of novel, eco-friendly, and natural-product-based antiviral agents.


Asunto(s)
Glicósidos , Virus del Mosaico del Tabaco , Relación Estructura-Actividad , Glicósidos/farmacología , Proteómica , Antivirales/farmacología , Diseño de Fármacos
2.
PeerJ ; 11: e16013, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37908414

RESUMEN

Bovine diarrhea is a multi-factorial disease and remains one of the biggest health problems in animal husbandry. The endemic trends of the main pathogens responsible for bovine diarrhea in Inner Mongolia have not been analyzed systematically before. Therefore, the purpose of this study was to estimate the prevalence of bovine diarrhea pathogens found in the scattered households of Inner Mongolia in China. Additionally, we assessed for differences in the prevalence of infection based on age and region, as well as determined local prevalence rates and the rates of mixed infections. Using a two-stage random sampling strategy, 3,050 serum samples were collected from 72 bovine herds in 11 leagues and cities in Inner Mongolia, and the positive rates of BVDV, BRV, BCoV, K99, and Mycobacterium paratuberculosis (M. paratuberculosis) antibodies in the samples were detected by ELISA to determine the epidemic trends and epidemic differences of the five pathogens in Inner Mongolia. The positive rates of antibodies based on serum samples were: BVDV, 18.79% (95% CI [17.44-20.22]); BRV, 12.39% (95% CI [11.27-13.61]); BCoV, 12.82% (95% CI [11.68-14.05]); K99, 13.80% (95% CI [12.62-15.07]); and M. paratuberculosis, 10.79% (95% CI [9.74-11.94]). The prevalence rates of BRV, BCoV and K99 at 0-2 months were significantly different from that at 2-6 months, 6-18 months and adult cattle (P < 0.05). The prevalence of BVDV and M. paratuberculosis was the highest in adult cattle, which was significantly different from that in other age groups (P < 0.05). Furthermore, obvious regional epidemiological differences among the five diseases were observed. There was a mixed infection of BRV+BCoV in each age stage, the highest mixed infection being BVDV+BRV+K99 at 0-2 months of age. Our results showed that the cattle of scattered households in the Inner Mongolia of China were endemicly infected with several important cattle pathogens. Most of the pathogens studied occurred between 0-2 months of age and were mixed infections, which greatly influences the health of the cattle and leads to economic loss. These findings are of practical significance for the future prevention and control of bovine diarrhea in the Inner Mongolia or other regions of China.


Asunto(s)
Diarrea Mucosa Bovina Viral , Coinfección , Virus de la Diarrea Viral Bovina , Paratuberculosis , Bovinos , Animales , Diarrea Mucosa Bovina Viral/epidemiología , Estudios Seroepidemiológicos , Anticuerpos Antivirales , China/epidemiología , Diarrea/epidemiología
3.
Neural Netw ; 164: 707-718, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37267848

RESUMEN

Directed graph is able to model asymmetric relationships between nodes and research on directed graph embedding is of great significance in downstream graph analysis and inference. Learning source and target embeddings of nodes separately to preserve edge asymmetry has become the dominant approach, but also poses challenge for learning representations of low or even zero in/out degree nodes that are ubiquitous in sparse graphs. In this paper, a collaborative bi-directional aggregation method (COBA) for directed graph embedding is proposed. Firstly, the source and target embeddings of the central node are learned by aggregating from the counterparts of the source and target neighbors, respectively; Secondly, the source/target embeddings of the zero in/out degree central nodes are enhanced by aggregating the counterparts of opposite-directional neighbors (i.e. target/source neighbors); Finally, source and target embeddings of the same node are correlated to achieve collaborative aggregation. Both the feasibility and rationality of the model are theoretically analyzed. Extensive experiments on real-world datasets demonstrate that COBA comprehensively outperforms state-of-the-art methods on multiple tasks and meanwhile validates the effectiveness of proposed aggregation strategies.


Asunto(s)
Aprendizaje
4.
Med Sci Monit ; 28: e935807, 2022 May 17.
Artículo en Inglés | MEDLINE | ID: mdl-35578564

RESUMEN

BACKGROUND The aim of this study was to explore the relationship between C-reactive protein (CRP) and respiratory diseases in patients with diabetic retinopathy. MATERIAL AND METHODS We identified 855 patients with diabetic retinopathy who met the inclusion criteria from the "Diabetes Complications Data Set" in the National Population Health Data Center. We divided patients into 3 groups according to CRP tertiles: Q1 (<0.3 mg/dL), Q2 (0.3-0.35 mg/dL), and Q3 (>0.35 mg/dL). A multivariate logistic regression model was used to evaluate the relationship between CRP and respiratory diseases. The area under the receiver operating characteristic (ROC) curve was used to investigate the independent predictive effect of CRP on respiratory diseases. RESULTS Of the 855 patients with diabetic retinopathy, 137 (16%) had respiratory diseases. Prevalence of respiratory diseases gradually increased with an increase in CRP level (P for trend=0.001). With CRP as a continuous variable in the logistic regression model adjusted for confounding factors (model 3), the odds ratio (OR) per 1 standard deviation increment of CRP was 1.25 (95% CI 1.07-1.45, P=0.004). When the lowest CRP tertile group was used as the reference group, the OR of the highest CRP tertile group was 1.99 (95% CI 1.22-1.3.26, P=0.006). Adding CRP to the risk factor model increased the area under the ROC curve (0.68 vs 0.65, P=0.017). Subgroup analysis showed that the relationship between CRP and respiratory diseases had no potential heterogeneity among subgroups. CONCLUSIONS CRP can be used as an effective biomarker in predicting risk of respiratory diseases in patients with diabetic retinopathy.


Asunto(s)
Proteína C-Reactiva , Diabetes Mellitus Tipo 2 , Retinopatía Diabética , Enfermedades Respiratorias , Biomarcadores , Proteína C-Reactiva/metabolismo , Diabetes Mellitus Tipo 2/complicaciones , Retinopatía Diabética/epidemiología , Humanos , Curva ROC , Enfermedades Respiratorias/complicaciones
6.
J Am Chem Soc ; 141(40): 16079-16084, 2019 Oct 09.
Artículo en Inglés | MEDLINE | ID: mdl-31514499

RESUMEN

Charge transport in single molecule junctions critically depends on the chemical identity of anchor groups used to connect molecular wires to electrodes. In this work, we report the charge transport properties of conjugated oligomers with oxazole anchors, focusing on the role of the heteroatom substitution position in terminal oxazole groups. Our results show that oxazole serves as an efficient anchor group to form stable gold-molecule-gold junctions. We further observe quantum interference (QI) effects in oxazole-terminated phenylene molecular junctions, including destructive QI in meta-substituted phenyl rings and constructive QI in para-substituted phenyl rings containing terminal oxazole groups with the same chemical constitution on both termini (i.e., O5O5 (5-oxazolyl) or O4O4 (4-oxazolyl) linkages on both termini). Surprisingly, meta-substituted phenyl rings with nonequivalent constitutions (i.e., O4O5 oxazole terminal linkages) show unexpectedly higher conductance as compared to para-substituted analogues. These results suggest that charge transport in oxazole-terminated molecules is determined by the heteroatom substitution position of the oxazole anchor in addition to the aryl substitution pattern of the π-conjugated core. Our results further show that conjugated molecules with homogeneous oxazole linkages obey a quantum circuit rule such that GO4-p-O4/GO4-m-O4 = GO5-p-O5/GO5-m-O5, where G is molecular conductance. Overall, our work provides key insight into the development of new chemistries for molecular circuitry in the rapidly advancing field of single molecule electronics.

7.
J Chem Phys ; 149(16): 163331, 2018 Oct 28.
Artículo en Inglés | MEDLINE | ID: mdl-30384691

RESUMEN

Dynamic fluorescence-based single-molecule imaging of λ-DNA molecules driven through agarose hydrogels by DC electric fields reveals that passage through the hydrogel (98.5% water content) induces mobility orthogonal to the external field. Tortuous paths followed by the DNA molecules, which are heavily entangled in the hydrogel mesh as their contour length is nearly 100 times the hydrogel mesh size of 200 nm, cause them to appear to diffuse orthogonal to the driving force. The higher the driving field, from 2 to 16 V/cm, the higher the off-axis dispersion is, over the same time interval. We measure the off-axis displacement distribution over 3 orders of magnitude of probability density and find a master curve after normalizing for time (t) elapsed, but the power of time for normalizing increases with the external field, from t0.25 to t0.6 with increasing field. Comparing trajectories over the same distance traveled in the electric field direction, we observe whereas for the highest field strengths DNA molecules come closest to taking the shortest trajectory between two points in space, deviations from the shortest trajectory grow larger and larger (up to 40% larger) as one approaches the case of small yet finite external field strength.


Asunto(s)
ADN/química , Hidrogeles/química , Microscopía Fluorescente
8.
Surg Radiol Anat ; 40(6): 609-614, 2018 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-29079941

RESUMEN

PURPOSE: The positional relationship between the mandibular canal and corresponding third molars is a key anatomic factor of inferior alveolar nerve (IAN) injury. The aim of the present study is to classify the anatomic three-dimensional relationship between the mandibular third molar and the mandibular canal on cone-beam computed tomography (CBCT) images. METHODS: This study used CBCT images to classify the positional relationship between the mandibular canal and corresponding third molars. CBCT images of 749 patients (1296 mandibular third molars) were analyzed to draw up a classification. RESULTS: On a total of 1296 third molars, the mandibular canal relative to the roots of the mandibular third molar was on the apical side (88.1%), followed by the buccal side (7.9%), the lingual side (3.5%), and then between the roots (0.5%). Ninety-five (7.1%) third molars had a close relation with the mandibular canal, while 1201 (92.7%) third molars had no direct contact. The percentage of the mandibular canal contacts with the mandibular third molar was higher when the mandibular canal was lingually positioned. CONCLUSIONS: The anatomic structures of the mandibular third molar and the mandibular canal may be helpful to make adequate surgical planning to avoid or reduce nerve involvement.


Asunto(s)
Tomografía Computarizada de Haz Cónico , Mandíbula/anatomía & histología , Tercer Molar/anatomía & histología , Adulto , Anciano , Humanos , Imagenología Tridimensional , Mandíbula/diagnóstico por imagen , Nervio Mandibular/anatomía & histología , Nervio Mandibular/diagnóstico por imagen , Persona de Mediana Edad , Tercer Molar/diagnóstico por imagen , Adulto Joven
9.
Front Neurosci ; 12: 1050, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30760972

RESUMEN

Muscle synergy reflects inherent coordination patterns of muscle groups as the human body finishes required movements. It may be still unknown whether the original muscle synergy of subjects may alter or not when exoskeletons are put on during their normal walking activities. This paper reports experimental results and presents analysis on muscle synergy from 17 able-bodied subjects with and without lower-limb exoskeletons when they performed normal walking tasks. The electromyography (EMG) signals of the tibialis anterior (TA), soleus (SOL), lateral gastrocnemius (GAS), vastus medialis oblique (VMO), vastus lateralis oblique (VLO), biceps femoris (BICE), semitendinosus (SEMI), and rectus femoris (RECT) muscles were extracted to obtain the muscle synergy. The quantitative results show that, when the subjects wore exoskeletons to walk normally, their mean muscle synergy changed from when they walked without exoskeletons. When the subjects walked with and without exoskeletons, statistically significant differences on sub-patterns of the muscles' synergies between the corresponding two groups could be found.

10.
Head Face Med ; 13(1): 2, 2017 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-28228135

RESUMEN

BACKGROUND: Cone beam computerized tomography (CBCT) has been widely used in dental implanting. However, the local hospitals usually don't have access to CBCT due to the cost and medical investment, especially in West of China. The doctors in local hospitals have to make reasonable dental planting using orthopantomography (OPG) to reduce risks. Therefore, it is clinically meaningful to determine the magnification rate of OPG to obtain correct diagnosis. This study investigated the magnification rate of OPG in measuring different maxillofacial loci compared with CBCT. METHODS: Eighty-six patients demanding dental implanting were scanned by CBCT and OPG. The vertical distance between the alveolar ridge crest of the maxillary first molar and the sinus bottom of the upper jaw, the distance between the alveolar ridge crest of the mandibular first molars and the top of nerviduct in the mandibular alveolar, and the distance between the alveolar ridge crest of the maxillary central incisors and the bottoms of the nasal cavities were measured. The horizontal distance in those loci were also measured. The distances derived from CBCT were used as reference. The distances between the two methods were compared using paired t-test. The magnification rates at these positions were calculated. The relationship between the data acquired from the two methods was analyzed Pearson correlation. RESULTS: The correlation coefficients (R) between the paired samples obtained from OPG and CBCT were highly related (P < 0.05) with R values varying from 0.840 and 0.959 in vertical distances and R values varying from 0.703 and 0.904 in horizontal distances. Compared with data obtained from CBCT, the mean vertical magnification rates were 11.38% and 12.95% vertically and 8.55% and 9.43% horizontally for the first molars in the right and left maxilla respectively; 7.26% and 6.35% vertically and 5.33% and 4.96% horizontally for the first molars in the right and left mandible respectively; and 5.55% and 4.84% vertically and 6.53% and 7.47% horizontally for the central incisors in the upper right and left jaws respectively. CONCLUSION: The magnification rates of OPG at these teeth are different. The distances measured by OPG were highly correlated with that measured by CBCT.


Asunto(s)
Proceso Alveolar/diagnóstico por imagen , Tomografía Computarizada de Haz Cónico/métodos , Implantes Dentales , Radiografía Panorámica/métodos , Adolescente , Adulto , Anciano , China , Estudios de Cohortes , Implantación Dental/efectos adversos , Implantación Dental/métodos , Femenino , Humanos , Masculino , Mandíbula/diagnóstico por imagen , Mandíbula/cirugía , Maxilar/diagnóstico por imagen , Maxilar/cirugía , Persona de Mediana Edad , Análisis de Regresión , Estudios Retrospectivos , Sensibilidad y Especificidad , Adulto Joven
11.
Nat Mater ; 14(6): 589-93, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25822692

RESUMEN

In contrast to Brownian transport, the active motility of microbes, cells, animals and even humans often follows another random process known as truncated Lévy walk. These stochastic motions are characterized by clustered small steps and intermittent longer jumps that often extend towards the size of the entire system. As there are repeated suggestions, although disagreement, that Lévy walks have functional advantages over Brownian motion in random searching and transport kinetics, their intentional engineering into active materials could be useful. Here, we show experimentally in the classic active matter system of intracellular trafficking that Brownian-like steps self-organize into truncated Lévy walks through an apparent time-independent positive feedback such that directional persistence increases with the distance travelled persistently. A molecular model that allows the maximum output of the active propelling forces to fluctuate slowly fits the experiments quantitatively. Our findings offer design principles for programming efficient transport in active materials.


Asunto(s)
Células , Endosomas/metabolismo , Animales , Transporte Biológico Activo
12.
Langmuir ; 30(16): 4760-6, 2014 Apr 29.
Artículo en Inglés | MEDLINE | ID: mdl-24734998

RESUMEN

Particle tracking, the analysis of individual moving elements in time series of microscopic images, enables burgeoning new applications, but there is need to better resolve conformation and dynamics. Here we describe the advantages of Delaunay triangulation to extend the capabilities of particle tracking in three areas: (1) discriminating irregularly shaped objects, which allows one to track items other than point features; (2) combining time and space to better connect missing frames in trajectories; and (3) identifying shape backbone. To demonstrate the method, specific examples are given, involving analyzing the time-dependent molecular conformations of actin filaments and λ-DNA. The main limitation of this method, shared by all other clustering techniques, is the difficulty to separate objects when they are very close. This can be mitigated by inspecting locally to remove edges that are longer than their neighbors and also edges that link two objects, using methods described here, so that the combination of Delaunay triangulation with edge removal can be robustly applied to processing large data sets. As common software packages, both commercial and open source, can construct Delaunay triangulation on command, the methods described in this paper are both computationally efficient and easy to implement.

13.
ACS Nano ; 7(11): 9735-42, 2013 Nov 26.
Artículo en Inglés | MEDLINE | ID: mdl-24168181

RESUMEN

Single-molecule fluorescence imaging of adsorption onto initially bare surfaces shows that polymer chains need not localize immediately after arrival. In a system optimized to present limited adsorption sites (quartz surface to which polyethylene glycol (PEG) chains adsorb from aqueous solution at pH 8.2), we find that some chains diffuse back into bulk solution and readsorb at some distance away, sometimes multiple times before they either localize at a stable position or diffuse away into bulk solution. This mechanism of surface diffusion is considerably more rapid than the classical model in which adsorbed polymers crawl on surfaces while the entire molecule remains adsorbed, suggesting the conceptual generality of a recent report ( Phys. Rev. Lett. 2013 , 110 , 256101 ) but in a new experimental system and with comparison of different chain lengths. We find the trajectories with jumps to follow a truncated Lévy distribution of step size with limiting slope -2.5, consistent with a well-defined, rapid surface diffusion coefficient over the times we observe. The broad waiting time distribution appears to reflect that polymer chains possess a broad distribution of bound fraction: the smaller the bound fraction of a given chain, the shorter the surface residence time before executing the next surface jump.

14.
ACS Nano ; 7(10): 8634-44, 2013 Oct 22.
Artículo en Inglés | MEDLINE | ID: mdl-23971739

RESUMEN

We describe a simple automated method to extract and quantify transient heterogeneous dynamical changes from large data sets generated in single-molecule/particle tracking experiments. Based on wavelet transform, the method transforms raw data to locally match dynamics of interest. This is accomplished using statistically adaptive universal thresholding, whose advantage is to avoid a single arbitrary threshold that might conceal individual variability across populations. How to implement this multiscale method is described, focusing on local confined diffusion separated by transient transport periods or hopping events, with three specific examples: in cell biology, biotechnology, and glassy colloid dynamics. The discussion is generalized within the framework of continuous time random walk. This computationally efficient method can run routinely on hundreds of millions of data points analyzed within an hour on a desktop personal computer.

15.
Cryst Growth Des ; 10(6): 2515-2521, 2010 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-20953348

RESUMEN

The measured induction times in droplet-based microfluidic systems are stochastic and are not described by the deterministic population balances or moment equations commonly used to model the crystallization of amino acids, proteins, and active pharmaceutical ingredients. A stochastic model in the form of a Master equation is formulated for crystal nucleation in droplet-based microfluidic systems for any form of nucleation rate expression under conditions of time-varying supersaturation. An analytical solution is provided to describe the (1) time evolution of the probability of crystal nucleation, (2) the average number of crystals that will form at time t for a large number of droplets, (3) the induction time distribution, and (4) the mean, most likely, and median induction times. These expressions are used to develop methods for determining the nucleation kinetics. Nucleation kinetics are determined from induction times measured for paracetamol and lysozyme at high supersaturation in an evaporation-based high-throughput crystallization platform, which give low prediction errors when the nucleation kinetics were used to predict induction times for other experimental conditions. The proposed stochastic model is relevant to homogeneous and heterogeneous crystal nucleation in a wide range of droplet-based and microfluidic crystallization platforms.

16.
Nan Fang Yi Ke Da Xue Xue Bao ; 29(3): 497-9, 2009 Mar.
Artículo en Chino | MEDLINE | ID: mdl-19304535

RESUMEN

OBJECTIVE: To investigate the relation between CD4(+) and CD8(+) T lymphocyte infiltration and apoptosis of the neurons in the local traumatic brain tissue after brain trauma in rats. METHODS: In rat models of brain trauma, the changes in the number of CD4(+) and CD8(+) T lymphocytes and the apoptosis of neurons in the local traumatic brain tissue were observed by immunohistochemistry at different time points after brain trauma. RESULTS: Twenty-four hours after brain trauma, a significant increase in the number of CD4(+) and CD8(+) T lymphocytes occurred in the injured brain tissue, both reaching the highest levels on day 10, at the point of which the number of CD4(+) cells increased by about 15 folds and that of CD8(+) cells by about 20 folds compared with the control groups. The CD4(+) and CD8(+) T lymphocytes both began to decrease 30 days after the injury. A similar pattern of alterations was found in the apoptosis of neurons in the local brain tissue. Correlation analysis demonstrated a close positive correlation between the changes in CD4(+) and CD8(+) lymphocyte numbers and the number apoptotic neurons in the injured brain tissue. CONCLUSIONS: Brain trauma induces obvious increases in CD4(+) and CD8(+) T lymphocytes and enhanced cellular immune response in the injured brain tissue to mediate neuronal apoptosis and further exacerbate the brain tissue injuries.


Asunto(s)
Apoptosis/inmunología , Lesiones Encefálicas/inmunología , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/inmunología , Neuronas/patología , Animales , Lesiones Encefálicas/patología , Linfocitos T CD4-Positivos/citología , Linfocitos T CD8-positivos/citología , Femenino , Inmunidad Celular , Masculino , Neuronas/inmunología , Distribución Aleatoria , Ratas , Ratas Sprague-Dawley
17.
Anal Biochem ; 387(1): 42-53, 2009 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-19166806

RESUMEN

A soft-modeling multivariate numerical approach that combines self-modeling curve resolution (SMCR) and mixed Lorentzian-Gaussian curve fitting was successfully implemented for the first time to elucidate spatially and spectroscopically resolved spectral information from infrared imaging data of oral mucosa cells. A novel variant form of the robust band-target entropy minimization (BTEM) SMCR technique, coined as hierarchical BTEM (hBTEM), was introduced to first cluster similar cellular infrared spectra using the unsupervised hierarchical leader-follower cluster analysis (LFCA) and subsequently apply BTEM to clustered subsets of data to reconstruct three protein secondary structure (PSS) pure component spectra-alpha-helix, beta-sheet, and ambiguous structures-that associate with spatially differentiated regions of the cell infrared image. The Pearson VII curve-fitting procedure, which approximates a mixed Lorentzian-Gaussian model for spectral band shape, was used to optimally curve fit the resolved amide I and II bands of various hBTEM reconstructed PSS pure component spectra. The optimized Pearson VII band-shape parameters and peak center positions serve as means to characterize amide bands of PSS spectra found in various cell locations and for approximating their actual amide I/II intensity ratios. The new hBTEM methodology can also be potentially applied to vibrational spectroscopic datasets with dynamic or spatial variations arising from chemical reactions, physical perturbations, pathological states, and the like.


Asunto(s)
Mucosa Bucal/citología , Estructura Secundaria de Proteína , Espectrofotometría Infrarroja/métodos , Amidas/química , Análisis por Conglomerados , Entropía , Humanos , Mucosa Bucal/química , Proteínas/química , Espectroscopía Infrarroja por Transformada de Fourier
18.
Analyst ; 133(10): 1395-408, 2008 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-18810288

RESUMEN

A suite of numerical techniques was utilized in a concerted fashion for the efficacious multivariate chemometrics analysis of hyperspectral infrared imaging data of exfoliated oral mucosa cells. Based on the vector representation of infrared spectrum a1xnu), spectral vector properties (SVP) are demonstrated to possess underpinning spectral information that was exploited in crucial chemometrics analyses; which include outlier spectra identification, selection for a subset of imaged mid-infrared spectra that contain good oral mucosa cell signals, and, for the first time, obtain major biochemical constituent spectra via the band-target entropy minimization (BTEM) curve resolution algorithm. The relative concentration spatial distribution of the major biochemical constituents observed, namely membrane lipids and various cellular protein structures (alpha-helix, beta-sheet, turns and bends), were subsequently acquired through multi-linear regression and were displayed as chemical contour maps. Amongst the set of numerical algorithms employed, two novel unsupervised clustering algorithms were developed and tested. One is useful for outlier spectra detection, and the other aids the selection of pertinent spatially distributed spectra that possess oral mucosa cell mid-infrared spectra with good signal-to-noise ratio. It is anticipated that this developed numerical suite will serve as an effective multivariate chemometrics protocol for cellular studies and biomedical diagnostics via infrared imaging.


Asunto(s)
Algoritmos , Lípidos/análisis , Mucosa Bucal/química , Proteínas/análisis , Humanos , Mucosa Bucal/citología , Análisis Multivariante , Espectrofotometría Infrarroja/métodos
19.
Nano Lett ; 7(9): 2693-700, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17676921

RESUMEN

Droplets of liquid drying on a surface with pinned contact area develop an internal hydrodynamic flow that carries entrained particles to the air-liquid-substrate interface. We use this phenomenon in cylindrical, micrometer-sized droplets of large aspect ratio (more than 1000:1) to align, position, and place individual anisotropic nanostructures such as single-walled carbon nanotubes (SWNT). More than 84% of SWNT are aligned in parallel within +/-5 degrees relative to the target axis of alignment. A potential flow model accurately describes and quantifies the statistical variation in the positioning of the nanostructures. We demonstrate for the first time the top-down parallel alignment and placement of individual (unbundled) nanotubes from solution electrically contacted across gold electrodes.


Asunto(s)
Cristalización/métodos , Microfluídica/métodos , Micromanipulación/métodos , Modelos Teóricos , Nanotecnología/métodos , Nanotubos de Carbono/química , Nanotubos de Carbono/ultraestructura , Anisotropía , Simulación por Computador , Tamaño de la Partícula , Estrés Mecánico
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