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1.
Nat Plants ; 6(4): 404-415, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32296141

RESUMO

Decoding wound signalling in plants is critical for understanding various aspects of plant sciences, from pest resistance to secondary metabolite and phytohormone biosynthesis. The plant defence responses are known to primarily involve NADPH-oxidase-mediated H2O2 and Ca2+ signalling pathways, which propagate across long distances through the plant vasculature and tissues. Using non-destructive optical nanosensors, we find that the H2O2 concentration profile post-wounding follows a logistic waveform for six plant species: lettuce (Lactuca sativa), arugula (Eruca sativa), spinach (Spinacia oleracea), strawberry blite (Blitum capitatum), sorrel (Rumex acetosa) and Arabidopsis thaliana, ranked in order of wave speed from 0.44 to 3.10 cm min-1. The H2O2 wave tracks the concomitant surface potential wave measured electrochemically. We show that the plant RbohD glutamate-receptor-like channels (GLR3.3 and GLR3.6) are all critical to the propagation of the wound-induced H2O2 wave. Our findings highlight the utility of a new type of nanosensor probe that is species-independent and capable of real-time, spatial and temporal biochemical measurements in plants.

2.
Diabetes ; 2020 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-32152206

RESUMO

Despite considerable progress, development of glucose-responsive insulins (GRI) still largely depends on empirical knowledge and tedious experimentation - especially on rodents. To assist the rational design and clinical translation of the therapeutic, we present a Pharmacokinetic Algorithm Mapping GRI Efficacies in Rodents and Humans (PAMERAH), built upon our previous human model. PAMERAH constitutes a framework for predicting the therapeutic efficacy of a GRI candidate from its user-specified mechanism of action, kinetics, and dosage, which we show is accurate when checked against data from experiments and literature. Results from simulated glucose clamps also agree quantitatively with recent GRI publications. We demonstrate that the model can be used to explore the vast number of permutations constituting the GRI parameter space, and thereby identify the optimal design ranges that yield desired performance. A design guide aside, PAMERAH more importantly can facilitate GRI's clinical translation by connecting each candidate's efficacies in rats, mice, and humans. The resultant mapping helps find GRIs which appear promising in rodents but underperform in humans (i.e. false-positives). Conversely, it also allows for the discovery of optimal human GRI dynamics not captured by experiments on a rodent population (false-negatives). We condense such information onto a translatability grid as a straightforward, visual guide for GRI development.

4.
Small ; 16(21): e1907640, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32196921

RESUMO

In the last decade, along with the increasing use of graphene oxide (GO) in various applications, there is also considerable interest in understanding its effects on human health. Only a few experimental approaches can simulate common routes of exposure, such as ingestion, due to the inherent complexity of the digestive tract. This study presents the synthesis of size-sorted GO of sub-micrometer- or micrometer-sized lateral dimensions, its physicochemical transformations across mouth, gastric, and small intestinal simulated digestions, and its toxicological assessment against a physiologically relevant, in vitro cellular model of the human intestinal epithelium. Results from real-time characterization of the simulated digestas of the gastrointestinal tract using multi-angle laser diffraction and field-emission scanning electron microscopy show that GO agglomerates in the gastric and small intestinal phase. Extensive morphological changes, such as folding, are also observed on GO following simulated digestion. Furthermore, X-ray photoelectron spectroscopy reveals that GO presents covalently bound N-containing groups on its surface. It is shown that the GO employed in this study undergoes reduction. Toxicological assessment of the GO small intestinal digesta over 24 h does not point to acute cytotoxicity, and examination of the intestinal epithelium under electron microscopy does not reveal histological alterations. Both sub-micrometer- and micrometer-sized GO variants elicit a 20% statistically significant increase in reactive oxygen species generation compared to the untreated control after a 6 h exposure.

5.
Nano Lett ; 2020 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-32058726

RESUMO

Nanostructured fibers provide a basis for a unique class of multifunctional textiles, composites, and membrane applications, including those capable of chromatic modulating because of their high aspect ratio, surface area, and processing capability. Here in, we utilize two-dimensional (2D) materials including molybdenum disulfide (MoS2) and hexagonal boron nitride (hBN) to generate single layer Archimedean scroll fibers, possessing cross sections formed from a single 2D molecular layer. Chemical vapor deposited (CVD) monolayer MoS2 (0.29-0.33% in volume) and 226-259 nm-thick poly(methyl methacrylate) (PMMA) were used to create Bragg reflector fibers, exploiting the anisotropic function, exhibiting reflection at 630-709 nm, and verifying the highly ordered nanoinclusions. The Bragg reflectors show a memory response to heating and cooling, which switches the reflection wavelength from 629 to 698 nm. We simulate the reflection and transmission spectra of MoS2/PMMA and MoS2/polydimethylsiloxane layered composites to provide the design of scroll fiber composites using the transfer matrix methods. Moreover, we demonstrate the incorporation of a few-layer CVD hBN into the scroll fiber composite that emits photons at 576 nm. The highly oriented layered structures extend the capability of the fiber nanocomposites to take advantage of anisotropic optical, electrical, and thermal properties unique to 2D materials.

6.
ACS Sens ; 5(2): 327-337, 2020 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-31989811

RESUMO

The monitoring of biopharmaceutical critical quality attributes in-process, at both the process development and manufacturing stages, is necessary for the implementation of process analytical technology and quality-by-design principles. Among these attributes, it is important to monitor and control protein aggregation during the manufacturing of biological therapeutics to prevent adverse immunogenic responses and minimize negative impacts on drug deliverability. In this work, we explore hydrogel-encapsulated, label-free fluorescent nanosensors for the characterization of protein aggregation. A mathematical model is used to describe the diffusion and binding of a series of stressed pharmaceutical samples to such sensors, describing their dynamic response. We use mathematical modeling to map the influence of hydrogel properties on the separation performance, given the composition of UV-stressed IgG1 samples. Using this modified model, the compositions of light-stressed IgG1 samples were fit to experimental data and correlated with size-exclusion chromatography data. The results demonstrate the ability to detect the presence of high-molecular-weight protein species at a concentration as low as 1%. This work represents a significant step toward the development and deployment of rapid process analytical technologies for biopharmaceutical characterization.

7.
Nano Lett ; 20(2): 812-819, 2020 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-31670525

RESUMO

Nanolenses of alkali metal halides can be a unique optical element due to their hygroscopicity, optical transparency, and high mobility of constituent ions. It has been challenging, however, to form and place such lenses in a controlled manner. Here, we report micro/nanolenses of various alkali metal halides arranged as a one-dimensional (1D) array, using the exterior of single-walled carbon nanotubes (SWNTs) as a template for forming the lenses. Applying an electrical bias to an aqueous solution of alkali metal halides placed at the end of an SWNT array causes ionic transport along the exterior of SWNTs and the subsequent formation of salt micro/nanocrystals. The crystals serve as micro/nanolenses that optically visualize individual SWNTs and amplify their Raman scattering by orders of magnitude. Molecules dissolved in the ionic solution can be electrokinetically transported along the nanotubes, captured within the lenses, and analyzed by Raman spectroscopy, which we demonstrate by detecting ∼12 attomoles of glucose and 2 femtomoles of urea. The hygroscopic salt nanolenses are robust under various ambient conditions indefinitely, by transitioning to liquid droplets above their deliquescence relative humidity, yet can be removed nondestructively by water. Our approach could have broad implications in the optical visualization of 1D nanostructures, molecular transport or chemical reactions in 1D space, and molecular spectroscopy in salty environments.

8.
Anal Chem ; 92(1): 916-923, 2020 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-31829619

RESUMO

Nanoparticle-based optical sensors are capable of highly sensitive and selective chemical interactions and can form the basis of molecular recognition for various classes of analytes. However, their incorporation into standardized in vitro assays has been limited by their incompatibility with packaging or form factors necessary for specific applications. Here, we have developed a technique for immobilizing nIR-fluorescent single-walled carbon nanotube (SWCNT) sensors on seven different types of paper substrates including nitrocellulose, nylon, poly(vinylidene fluoride), and cellulose. Sensors remain functional upon immobilization and exhibit nIR fluorescence in nonaqueous solvent systems. We then extend this system to the Corona Phase Molecular Recognition (CoPhMoRe) approach of synthetic molecular recognition by screening ssDNA-wrapped SWCNTs with different sequences against a panel of fat-soluble vitamins in canola oil, identifying a sensor which responds to ß-carotene with a dissociation constant of 2.2 µM. Moreover, we pattern hydrophobic regions onto nitrocellulose using the wax printing method and form one-dimensional sensor barcodes for rapid multiplexing. Using a sensor array of select ssDNA wrappings, we are able to distinguish between Cu(II), Cd(II), Hg(II), and Pb(II) at a concentration of 100 µM. Finally, we demonstrate that immobilized sensors remain fluorescent and responsive for nearly 60 days when stability is addressed. This work represents a significant step toward the deployment of fluorescent nanoparticle sensors for point-of-use applications.

9.
J Anim Ecol ; 89(1): 161-172, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31173339

RESUMO

It is fundamentally important for many animal ecologists to quantify the costs of animal activities, although it is not straightforward to do so. The recording of triaxial acceleration by animal-attached devices has been proposed as a way forward for this, with the specific suggestion that dynamic body acceleration (DBA) be used as a proxy for movement-based power. Dynamic body acceleration has now been validated frequently, both in the laboratory and in the field, although the literature still shows that some aspects of DBA theory and practice are misunderstood. Here, we examine the theory behind DBA and employ modelling approaches to assess factors that affect the link between DBA and energy expenditure, from the deployment of the tag, through to the calibration of DBA with energy use in laboratory and field settings. Using data from a range of species and movement modes, we illustrate that vectorial and additive DBA metrics are proportional to each other. Either can be used as a proxy for energy and summed to estimate total energy expended over a given period, or divided by time to give a proxy for movement-related metabolic power. Nonetheless, we highlight how the ability of DBA to predict metabolic rate declines as the contribution of non-movement-related factors, such as heat production, increases. Overall, DBA seems to be a substantive proxy for movement-based power but consideration of other movement-related metrics, such as the static body acceleration and the rate of change of body pitch and roll, may enable researchers to refine movement-based metabolic costs, particularly in animals where movement is not characterized by marked changes in body acceleration.

10.
Small ; 16(3): e1905985, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31854047

RESUMO

2D semiconducting transition metal dichalcogenides (TMDs) are endowed with fascinating optical properties especially in their monolayer limit. Insulating hBN films possessing customizable thickness can act as a separation barrier to dictate the interactions between TMDs. In this work, vertical layered heterostructures (VLHs) of WS2 :hBN:WS2 are fabricated utilizing chemical vapor deposition (CVD)-grown materials, and the optical performance is evaluated through photoluminescence (PL) spectroscopy. Apart from the prohibited indirect optical transition due to the insertion of hBN spacers, the variation in the doping level of WS2 drives energy transfer to arise from the layer with lower quantum efficiency to the other layer with higher quantum efficiency, whereby the total PL yield of the heterosystem is increased and the stack exhibits a higher PL intensity compared to the sum of those in the two WS2 constituents. Such doping effects originate from the interfaces that WS2 monolayers reside on and interact with. The electron density in the WS2 is also controlled and subsequent modulation of PL in the heterostructure is demonstrated by applying back-gated voltages. Other influential factors include the strain in WS2 and temperature. Being able to tune the energy transfer in the VLHs may expand the development of photonic applications in 2D systems.

11.
Nano Lett ; 19(11): 7712-7724, 2019 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-31565943

RESUMO

The corona phase-the adsorbed layer of polymer, surfactant, or stabilizer molecules around a nanoparticle-is typically utilized to disperse nanoparticles into a solution or solid phase. However, this phase also controls molecular access to the nanoparticle surface, a property important for catalytic activity and sensor applications. Unfortunately, few methods can directly probe the structure of this corona phase, which is subcategorized as either a hard, immobile corona or a soft, transient corona in exchange with components in the bulk solution. In this work, we introduce a molecular probe adsorption (MPA) method for measuring the accessible nanoparticle surface area using a titration of a quenchable fluorescent molecule. For example, riboflavin is utilized to measure the surface area of gold nanoparticle standards, as well as corona phases on dispersed single-walled carbon nanotubes and graphene sheets. A material balance on the titration yields certain surface coverage parameters, including the ratio of the surface area to dissociation constant of the fluorophore, q/KD, as well as KD itself. Uncertainty, precision, and the correlation of these parameters across different experimental systems, preparations, and modalities are all discussed. Using MPA across a series of corona phases, we find that the Gibbs free energy of probe binding scales inversely with the cube root of surface area, q. In this way, MPA is the only technique to date capable of discerning critical structure-property relationships for such nanoparticle surface phases. Hence, MPA is a rapid quantitative technique that should prove useful for elucidating corona structure for nanoparticles across different systems.

12.
ACS Sens ; 4(10): 2566-2570, 2019 10 25.
Artigo em Inglês | MEDLINE | ID: mdl-31576740

RESUMO

Biologging is a scientific endeavor that studies the environment and animals within it by outfitting the latter with sensors of their dynamics as they roam freely in their natural habitats. As wearable technologies advance for the monitoring of human health, it may be instructive to reflect on the successes and failures of biologging in field biology over the past few decades. Several lessons may be of value. Physiological sensors can "encode" for a wider number of states than the one explicitly targeted, although the limits of this are debatable. The combination of orthogonal sensors turns out to be critical to delivering a high value data set. Sensor fusion and engineering for longevity are also important for success. This Perspective highlights successful strategies for biologging that hold promise for human health monitoring.

13.
ACS Nano ; 13(10): 11809-11824, 2019 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-31532624

RESUMO

Nanoporous graphene is a promising candidate material for gas separation membranes, due to its atomic thickness and low cross-membrane transport resistance. The mechanisms of gas permeation through graphene nanopores, in both the large and small pore size limits, have been reported in the literature. However, mechanistic insights into the crossover from the small pore size limit to the large pore size limit are still lacking. In this study, we develop a comprehensive theoretical framework to predict gas permeance through graphene nanopores having a wide range of diameters using analytical equations. We formulate the transport kinetics associated with the direct impingement from the bulk and with the surface diffusion from the adsorption layer on graphene and then combine them to predict the overall gas permeation rate using a reaction network model. We also utilize molecular dynamics simulations to validate and calibrate our theoretical model. We show that the rates of both the direct impingement and the surface diffusion pathways need to be corrected using different multiplicative factors, which are functions of temperature, gas kinetic diameter, and pore diameter. Further, we find a minor spillover pathway that originates from the surface adsorption layer, but is not included in our theoretical model. Finally, we utilize the corrected model to predict the permeances of CO2, CH4, and Ar through graphene nanopores. We show that as the pore diameter increases, gas transport through graphene nanopores can transition from being translocation dominated (pore diameter < 0.7 nm), to surface pathway dominated (pore diameter 1-2 nm), and finally to direct pathway dominated (pore diameter > 4 nm). The various gas permeation mechanisms outlined in this study will be particularly useful for the rational design of membranes made out of two-dimensional materials such as graphene for gas separation applications.

14.
Cancer Res ; 79(17): 4515-4523, 2019 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-31292162

RESUMO

Pancreatic ductal adenocarcinoma (PDAC) is a highly desmoplastic cancer with limited treatment options. There is an urgent need for tools that monitor therapeutic responses in real time. Drugs such as gemcitabine and irinotecan elicit their therapeutic effect in cancer cells by producing hydrogen peroxide (H2O2). In this study, specific DNA-wrapped single-walled carbon nanotubes (SWCNT), which precisely monitor H2O2, were used to determine the therapeutic response of PDAC cells in vitro and tumors in vivo. Drug therapeutic efficacy was evaluated in vitro by monitoring H2O2 differences in situ using reversible alteration of Raman G-bands from the nanotubes. Implantation of the DNA-SWCNT probe inside the PDAC tumor resulted in approximately 50% reduction of Raman G-band intensity when treated with gemcitabine versus the pretreated tumor; the Raman G-band intensity reversed to its pretreatment level upon treatment withdrawal. In summary, using highly specific and sensitive DNA-SWCNT nanosensors, which can determine dynamic alteration of hydrogen peroxide in tumor, can evaluate the effectiveness of chemotherapeutics. SIGNIFICANCE: A novel biosensor is used to detect intratumoral hydrogen peroxide, allowing real-time monitoring of responses to chemotherapeutic drugs.

15.
Small ; 15(37): e1901468, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31338962

RESUMO

Colloidal dispersions of nanomaterials are often polydisperse in size, significantly complicating their characterization. This is particularly true for materials early in their historical development due to synthetic control, dispersion efficiency, and instability during storage. Because a wide range of system properties and technological applications depend on particle dimensions, it remains an important problem in nanotechnology to identify a method for the routine characterization of polydispersity in nanoparticle samples, especially changes over time. Commonly employed methods such as dynamic light scattering or analytical ultracentrifugation (AUC) accurately estimate only the first moment of the distribution or are not routine. In this work, the use of single-particle tracking (SPT) to probe size distributions of common nanoparticle dispersions, including polystyrene nanoparticles, single-walled carbon nanotubes, graphene oxide, chitosan-tripolyphosphate, acrylate, hexagonal boron nitride, and poly(lactic-co-glycolic acid), is proposed and explored. The analysis of particle tracks is conducted using a newly developed Bayesian algorithm that is called Maximum A posteriori Nanoparticle Tracking Analysis. By combining SPT and AUC techniques, it is shown that it is possible to independently estimate the mean aspect ratio of anisotropic particles, an important characterization property. It is concluded that SPT provides a facile, rapid analytical method for routine nanomaterials characterization.

16.
Angew Chem Int Ed Engl ; 58(27): 9204-9209, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31132208

RESUMO

Synthesis of low-dimensional carbon nanomaterials such as carbon nanotubes (CNTs) is a key driver for achieving advances in energy storage, computing, and multifunctional composites, among other applications. Here, we report high-yield thermal chemical vapor deposition (CVD) synthesis of CNTs catalyzed by reagent-grade common sodium-containing compounds, including NaCl, NaHCO3 , Na2 CO3 , and NaOH, found in table salt, baking soda, and detergents, respectively. Coupled with an oxidative dehydrogenation reaction to crack acetylene at reduced temperatures, Na-based nanoparticles have been observed to catalyze CNT growth at temperatures below 400 °C. Ex situ and in situ transmission electron microscopy (TEM) reveal unique CNT morphologies and growth characteristics, including a vaporizing Na catalyst phenomenon that we leverage to create CNTs without residual catalyst particles for applications that require metal-free CNTs. Na is shown to synthesize CNTs on numerous substrates, and as the first alkali group metal catalyst demonstrated for CNT growth, holds great promise for expanding the understanding of nanocarbon synthesis.

17.
ACS Nano ; 13(4): 3940-3952, 2019 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-30856320

RESUMO

The rapid and efficient characterization of polydisperse nanoparticle dispersions remains a challenge within nanotechnology and biopharmaceuticals. Current methods for particle sizing, such as dynamic light scattering, analytical ultracentrifugation, and field-flow fractionation, can suffer from a combination of statistical biases, difficult sample preparation, insufficient sampling, and ill-posed data analysis. As an alternative, we introduce a Bayesian method that we call maximum a posteriori nanoparticle tracking analysis (MApNTA) for estimating the size distributions of nanoparticle samples from high-throughput single-particle tracking experiments. We derive unbiased statistical models for two observable quantities in a typical nanoparticle trajectory-the mean square displacement and the trajectory length-as a function of the particle size and calculate size distributions using maximum a posteriori (MAP) estimation with cross validation to mildly regularize solutions. We show that this approach infers nanoparticle size distributions with high resolution by performing extensive Brownian dynamics simulations and experiments with mono- and polydisperse solutions of gold nanoparticles as well as single-walled carbon nanotubes. We further demonstrate particular utility for characterizing minority components and impurity populations and highlight this ability with the identification of an impurity in a commercially produced gold nanoparticle sample. Modern algorithms such as MApNTA should find widespread use in the routine characterization of complex nanoparticle dispersions, allowing for significant advances in nanoparticle synthesis, separation, and functionalization.

18.
Nat Nanotechnol ; 14(5): 447-455, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30804482

RESUMO

Plant genetic engineering is an important tool used in current efforts in crop improvement, pharmaceutical product biosynthesis and sustainable agriculture. However, conventional genetic engineering techniques target the nuclear genome, prompting concerns about the proliferation of foreign genes to weedy relatives. Chloroplast transformation does not have this limitation, since the plastid genome is maternally inherited in most plants, motivating the need for organelle-specific and selective nanocarriers. Here, we rationally designed chitosan-complexed single-walled carbon nanotubes, utilizing the lipid exchange envelope penetration mechanism. The single-walled carbon nanotubes selectively deliver plasmid DNA to chloroplasts of different plant species without external biolistic or chemical aid. We demonstrate chloroplast-targeted transgene delivery and transient expression in mature Eruca sativa, Nasturtium officinale, Nicotiana tabacum and Spinacia oleracea plants and in isolated Arabidopsis thaliana mesophyll protoplasts. This nanoparticle-mediated chloroplast transgene delivery tool provides practical advantages over current delivery techniques as a potential transformation method for mature plants to benefit plant bioengineering and biological studies.


Assuntos
Arabidopsis/genética , Quitosana/química , Cloroplastos/genética , Técnicas de Transferência de Genes , Nanotubos de Carbono/química , Nasturtium/genética , Plantas Geneticamente Modificadas/genética , Spinacia oleracea/genética , Tabaco/genética , Arabidopsis/metabolismo , Cloroplastos/metabolismo , Expressão Gênica , Nasturtium/metabolismo , Plantas Geneticamente Modificadas/metabolismo , Spinacia oleracea/metabolismo , Tabaco/metabolismo
19.
Nat Mater ; 18(2): 129-135, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30643239

RESUMO

The presence of extended defects or nanopores in two-dimensional (2D) materials can change the electronic, magnetic and barrier membrane properties of the materials. However, the large number of possible lattice isomers of nanopores makes their quantitative study a seemingly intractable problem, confounding the interpretation of experimental and simulated data. Here we formulate a solution to this isomer cataloguing problem (ICP), combining electronic-structure calculations, kinetic Monte Carlo simulations, and chemical graph theory, to generate a catalogue of unique, most-probable isomers of 2D lattice nanopores. The results demonstrate remarkable agreement with precise nanopore shapes observed experimentally in graphene and show that the thermodynamic stability of a nanopore is distinct from its kinetic stability. Triangular nanopores prevalent in hexagonal boron nitride are also predicted, extending this approach to other 2D lattices. The proposed method should accelerate the application of nanoporous 2D materials by establishing specific links between experiment and theory/simulations, and by providing a much-needed connection between molecular design and fabrication.

20.
Nanoscale ; 11(6): 2925-2937, 2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30688946

RESUMO

The nanometer placement of nanomaterials, such as nanoribbons and nanotubes, at a specific pitch and orientation on a surface, remains an unsolved fundamental problem in nanotechnology. In this work, we introduce and analyze the concept of a direct-write chemical vapor deposition (CVD) system that enables the in-place synthesis of such structures with control over orientation and characteristic features. A nanometer scale pore or conduit, called the nanonozzle, delivers precursor gases for CVD locally on a substrate, with spatial translation of either the nozzle or the substrate to enable a novel direct write (DW) tool. We analyze the nozzle under conditions where it delivers reactants to a substrate while translating at a constant velocity over the surface at a fixed reaction temperature. We formulate and solve a multi-phase three-dimensional reaction and diffusion model of the direct-write operation, and evaluate specific analytically-solvable limits to determine the allowable operating conditions, including pore dimensions, reactant flow rates, and nozzle translation speed. A Buckingham Π analysis identifies six dimensionless quantities crucial for the design and operation of the direct-write synthesis process. Importantly, we derive and validate what we call the ribbon extension inequality that brackets the allowable nozzle velocity relative to the CVD growth rate - a key constraint to enabling direct-write operation. Lastly, we include a practical analysis using attainable values towards the experimental design of such a system, building the nozzle around a commercially available near-field scanning optical microscopy (NSOM) tip as a feasible example.

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